Patent Publication Number: US-2019185460-A1

Title: Amine-based compound and organic light-emitting device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0176483, filed on Dec. 20, 2017, in the Korean Intellectual Property Office, and Korean Patent Application No. 10-2018-0137609, filed on Nov. 9, 2018, in the Korean Intellectual Property Office, the disclosure of each of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field 
     One or more embodiments relate to an amine-based compound and an organic light-emitting device including the same. 
     2. Description of the Related Art 
     Organic light-emitting devices (OLEDs) are self-emission devices that, as compared with related art devices, have wide viewing angles, high contrast ratios, short response times, and excellent brightness, driving voltage, and response speed characteristics, and produce full-color images. 
     OLEDs may include a first electrode disposed on a substrate, and may include a hole transport region, an emission layer, an electron transport region, and a second electrode sequentially disposed on the first electrode. Holes provided from the first electrode may move toward the emission layer through the hole transport region. Electrons provided from the second electrode may move toward the emission layer through the electron transport region. Carriers, such as holes and electrons, may recombine in the emission layer to produce excitons. These excitons transit from an excited state to a ground state to thereby generate light. 
     SUMMARY 
     An aspect according to one or more embodiments is directed toward an amine-based compound and an organic light-emitting device including the same. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     According to one or more embodiments, an amine-based compound is represented by one of Formulae 1A and 1B: 
     
       
         
         
             
             
         
       
     
     In Formulae 1A and 1B, 
     A 1  to A 5  may each independently be selected from a C 5 -C 30  carbocyclic group and a C 1 -C 30  heterocyclic group, 
     X 1  may be O, S, N-(L 1 ) a1 -(R 1 ) b1 , or C(R 9 )(R 10 ), 
     X 2  may be O, S, or C(R 11 )(R 12 ), 
     L 1  to L 3  may each independently be selected from a single bond, a substituted or unsubstituted C 5 -C 60  carbocyclic group, and a substituted or unsubstituted C 1 -C 60  heterocyclic group, 
     a1 to a3 may each independently be an integer from 1 to 5, 
     R 1  to R 12  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a substituted or unsubstituted C 1 -C 60  alkyl group, a substituted or unsubstituted C 2 -C 60  alkenyl group, a substituted or unsubstituted C 2 -C 60  alkynyl group, a substituted or unsubstituted C 1 -C 60  alkoxy group, a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted C 1 -C 60  heteroaryloxy group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), and —C(═O)(Q 1 ), 
     R 9  and R 10  and/or R 11  and R 12  may optionally be bound to each other to form a substituted or unsubstituted C 5 -C 30  carbocyclic group or a substituted or unsubstituted C 1 -C 30  heterocyclic group, 
     b1 to b3 and b5 to b8 may each independently be an integer from 1 to 10, 
     b4 may be an integer from 1 to 3, and 
     at least one substituent of the substituted C 5 -C 60  carbocyclic group, the substituted C 1 -C 60  heterocyclic group, the substituted C 1 -C 60  alkyl group, the substituted C 2 -C 60  alkenyl group, the substituted C 2 -C 60  alkynyl group, the substituted C 1 -C 60  alkoxy group, the substituted C 3 -C 10  cycloalkyl group, the substituted C 1 -C 10  heterocycloalkyl group, the substituted C 3 -C 10  cycloalkenyl group, the substituted C 1 -C 10  heterocycloalkenyl group, the substituted C 6 -C 60  aryl group, the substituted C 6 -C 60  aryloxy group, the substituted C 6 -C 60  arylthio group, the substituted C 1 -C 60  heteroaryl group, the substituted C 1 -C 60  heteroaryloxy group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from: 
     deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
     a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 11 )(Q 12 )(Q 13 ), —N(Q 11 )(Q 12 ), —B(Q 11 )(Q 12 ), —C(═O)(Q 11 ), —S(═O) 2 (Q 11 ), and —P(═O)(Q 11 )(Q 12 ); 
     a C 3 -C 00  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group; 
     a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, a terphenyl group, —Si(Q 21 )(Q 22 )(Q 23 ), —N(Q 21 )(Q 22 ), —B(Q 21 )(Q 22 ), —C(═O)(Q 21 ), —S(═O) 2 (Q 21 ), and —P(═O)(Q 21 )(Q 22 ); and 
     —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     wherein Q 1  to Q 3 , Q 11  to Q 13 , Q 21  to Q 23 , and Q 31  to Q 33  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryl group substituted with a C 1 -C 60  alkyl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group. 
     According to one or more embodiments, an organic light-emitting device may include: a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode, wherein the organic layer may include an emission layer and at least one amine-based compound described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic cross-sectional view of an embodiment of an organic light-emitting device; 
         FIG. 2  is a schematic cross-sectional view of an embodiment of an organic light-emitting device; 
         FIG. 3  is a schematic cross-sectional view of an embodiment of an organic light-emitting device; and 
         FIG. 4  is a schematic cross-sectional view of an embodiment of an organic light-emitting device. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in more detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of”, when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Further, the use of “may” when describing embodiments of the present invention refers to “one or more embodiments of the present invention.” 
     As used herein, the terms “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. Also, any numerical range recited herein is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of “1.0 to 10.0” is intended to include all subranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein. 
     As the inventive concept allows various modifications and include various embodiments, example embodiments will be illustrated in the drawings and described in more detail in the written description. Effects, features, and a method of achieving the inventive concept will become apparent by reference to the example embodiments of the inventive concept, together with the accompanying drawings. The inventive concept may, however, be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. 
     Hereinafter, the inventive concept will be described in more detail by explaining example embodiments of the inventive concept with reference to the attached drawings. Like reference numerals in the drawings denote like elements, and thus their description will not be repeated. 
     In the embodiments described in the present specification, an expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. 
     In the present specification, it is to be understood that the terms such as “including,” “having,” and “comprising” are intended to indicate the existence of the features or components disclosed in the specification, and are not intended to preclude the possibility that one or more other features or components may exist or may be added. 
     It will be understood that when a layer, region, or component is referred to as being “on” or “onto” another layer, region, or component, it may be directly or indirectly formed over the other layer, region, or component. That is, for example, intervening layers, regions, or components may be present. 
     Sizes of components in the drawings may be exaggerated for convenience of explanation. In other words, because sizes and thicknesses of components in the drawings are arbitrarily illustrated for convenience of explanation, the following embodiments are not limited thereto. 
     The amine-based compound may be represented by one of Formulae 1A and 1B: 
     
       
         
         
             
             
         
       
     
     wherein, in Formulae 1A and 1B, A 1  to A 5  may each independently be selected from a C 5 -C 30  carbocyclic group and a C 1 -C 30  heterocyclic group. 
     In some embodiments, in Formulae 1A and 1B, A 1  to A 5  may each independently be selected from a benzene group, an indene group, a naphthalene group, an anthracene group, a fluorene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a pyrrole group, an imidazole group, a pyrazole group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, an indole group, an isoindole group, an indazole group, a quinoline group, an isoquinoline group, a benzoquinoline group, a naphthyridine group, a quinoxaline group, a quinazoline group, a cinnoline group, a carbazole group, a phenanthridine group, an acridine group, a phenanthroline group, a phenazine group, a benzimidazole group, a furan group, a benzofuran group, a thiophene group, a benzothiophene group, a thiazole group, an isothiazole group, a benzothiazole group, an isoxazole group, an oxazole group, a triazole group, an oxadiazole group, a triazine group, a benzoxazole group, a dibenzofuran group, a dibenzothiophene group, a benzocarbazole group, and a dibenzocarbazole group. 
     In some embodiments, in Formulae 1A and 1B, A 1  to A 5  may each independently be selected from a benzene group, an indene group, a naphthalene group, an anthracene group, a fluorene group, a phenanthrene group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, and a carbazole group, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, A 1  to A 5  may each independently be selected from a benzene group and a naphthalene group, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, A 1  to A 5  may each independently be a benzene group, but embodiments are not limited thereto. 
     In Formulae 1A and 1B, X 1  may be O, S, N-(L 1 ) a1 -(R 1 ) b1 , or C(R 9 )(R 10 ), and X 2  may be O, S, or C(R 11 )(R 12 ). 
     In some embodiments, in Formulae 1A and 1B, X 1  may be N-(L 1 ) a1 -(R 1 ) b1 , and X 2  may be O, S, or C(R 11 )(R 12 ); or X 1  may be O, and X 2  may be C(R 11 )(R 12 ), but embodiments are not limited thereto. 
     In Formulae 1A and 1B, L 1  to L 3  may each independently be selected from a single bond, a substituted or unsubstituted C 5 -C 60  carbocyclic group, and a substituted or unsubstituted C 1 -C 60  heterocyclic group. 
     In some embodiments, in Formulae 1A and 1B, L 1  to L 3  may each independently be selected from a single bond, a benzene group, a pentalene group, an indene group, a naphthalene group, an azulene group, a heptalene group, an indacene group, an acenaphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphenylene group, a hexacene group, a pyrrole group, an imidazole group, a pyrazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, an isoindole group, an indole group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a phthalazine group, a naphthyridine group, a quinoxaline group, a quinazoline group, a cinnoline group, a carbazole group, a phenanthridine group, an acridine group, a phenanthroline group, a phenazine group, a benzimidazole group, a furan group, a benzofuran group, a thiophene group, a benzothiophene group, a thiazole group, an isothiazole group, a benzothiazole group, an iso-oxazole group, an oxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a benzoxazole group, a dibenzofuran group, a dibenzothiophene group, a benzocarbazole group, and a dibenzocarbazole group; and 
     a benzene group, a pentalene group, an indene group, a naphthalene group, an azulene group, a heptalene group, an indacene group, an acenaphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphenylene group, a hexacene group, a pyrrole group, an imidazole group, a pyrazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, an isoindole group, an indole group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a phthalazine group, a naphthyridine group, a quinoxaline group, a quinazoline group, a cinnoline group, a carbazole group, a phenanthridine group, an acridine group, a phenanthroline group, a phenazine group, a benzimidazole group, a furan group, a benzofuran group, a thiophene group, a benzothiophene group, a thiazole group, an isothiazole group, a benzothiazole group, an iso-oxazole group, an oxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a benzoxazole group, a dibenzofuran group, a dibenzothiophene group, a benzocarbazole group, and a dibenzocarbazole group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a C 6 -C 20  aryl group, a C 1 -C 20  heteroaryl group, and —Si(Q 31 )(Q 32 )(Q 33 ), 
     wherein, Q 31  to Q 33  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryl group substituted with a C 1 -C 60  alkyl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group. 
     In some embodiments, in Formulae 1A and 1B, L 1  to L 3  may each independently be selected from a single bond and groups represented by Formulae 3-1 to 3-46: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     wherein, in Formulae 3-1 to 3-46, 
     Y 1  may be O, S, C(Z 3 )(Z 4 ), N(Z 5 ), or Si(Z 6 )(Z 7 ), 
     Z 1  to Z 7  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 31 )(Q 32 )(Q 33 ), 
     d2 may be an integer from 0 to 2; when d2 is 2, at least two Z 1  groups may be identical to or different from each other, 
     d3 may be an integer from 0 to 3; when d3 is 2 or greater, at least two Z 1  groups (in (Z 1 ) d3 ) may be identical to or different from each other, and at least two Z 2  groups (in (Z 2 ) d3 ) may be identical to or different from each other, 
     d4 may be an integer from 0 to 4; when d4 is 2 or greater, at least two Z 1  groups (in (Z 1 ) d4 ) may be identical to or different from each other, and at least two Z 2  groups (in (Z 2 ) d4 ) may be identical to or different from each other, 
     d5 may be an integer from 0 to 5; when d5 is 2 or greater, at least two Z 1  groups (in (Z 1 ) d5 ) may be identical to or different from each other, and at least two Z 2  groups (in (Z 2 ) d5 ) may be identical to or different from each other, 
     d6 may be an integer from 0 to 6; when d6 is 2 or greater, at least two Z 1  groups (in (Z 1 ) d6 ) may be identical to or different from each other, and at least two Z 2  groups (in (Z 2 ) d6 ) may be identical to or different from each other, 
     d8 may be an integer from 0 to 8; when d8 is 2 or greater, at least two Z 1  groups may be identical to or different from each other, and 
     * and *′ each indicate a binding site to an adjacent atom. 
     In some embodiments, L 1  to L 3  may each independently be selected from a single bond and groups represented by Formulae 3-1 to 3-7, 3-31 to 3-34, 3-42, and 3-43. 
     In some embodiments, L 1  to L 3  may each independently be selected from a single bond and groups represented by Formulae 3-1, 3-2, and 3-34. 
     In some embodiments, in Formulae 3-1 to 3-46, Z 1  to Z 7  may each independently be selected from hydrogen, deuterium, —F, a cyano group, a methyl group, an ethyl group, an n-propyl group, a tert-butyl group, a phenyl group, and a naphthyl group, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, L 1  to L 3  may each independently be selected from a single bond and a benzene group; and 
     a benzene group substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a C 6 -C 20  aryl group, a C 1 -C 20  heteroaryl group, and —Si(Q 31 )(Q 32 )(Q 33 ), but embodiments are not limited thereto. 
     In Formulae 1A and 1B, a1 to a3 may each independently be an integer from 1 to 5. a1 indicates the number of L 1  groups; when a1 is 2 or greater, at least two L 1  groups may be identical to or different from each other. Descriptions for a2 and a3 may be understood by referring to (may be the same as) the descriptions for a1 provided herein. 
     In some embodiments, in Formulae 1A and 1B, a1 to a3 may each independently be an integer from 1 to 3. 
     For example, a1 to a3 may each be 1, but embodiments are not limited thereto. 
     In Formulae 1A and 1B, R 1  to R 12  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a substituted or unsubstituted C 1 -C 60  alkyl group, a substituted or unsubstituted C 2 -C 60  alkenyl group, a substituted or unsubstituted C 2 -C 60  alkynyl group, a substituted or unsubstituted C 1 -C 60  alkoxy group, a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted C 1 -C 60  heteroaryloxy group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), and —C(═O)(Q 1 ), 
     R 9  and R 10  and/or R 11  and R 12  may optionally be bound to each other to form a substituted or unsubstituted C 5 -C 30  carbocyclic group or a substituted or unsubstituted C 1 -C 30  heterocyclic group, 
     wherein, Q 1  to Q 3  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryl group substituted with a C 1 -C 60  alkyl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group. 
     In some embodiments, in Formulae 1A and 1B, R 1  and R 2  may each independently be selected from a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; and 
     a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a C 1 -C 60  alkyl group, a C 1 -C 60  alkoxy group, a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 31 )(Q 32 ), and —Si(Q 31 )(Q 32 )(Q 33 ). 
     In some embodiments, in Formulae 1A and 1B, R 1  and R 2  may each independently be selected from a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoxazolyl group, a benzimidazolyl group, a furanyl group, a benzofuranyl group, a thiophenyl group, a benzothiophenyl group, a thiazolyl group, an isothiazolyl group, a benzothiazolyl group, an isoxazolyl group, an oxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a benzoxazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group; and 
     a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoxazolyl group, a benzimidazolyl group, a furanyl group, a benzofuranyl group, a thiophenyl group, a benzothiophenyl group, a thiazolyl group, an isothiazolyl group, a benzothiazolyl group, an isoxazolyl group, an oxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a benzoxazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a C 6 -C 20  aryl group, a C 1 -C 20  heteroaryl group, and —Si(Q 31 )(Q 32 )(Q 33 ), but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, R 1  and R 2  may each independently be selected from groups represented by Formulae 5-1 to 5-79, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
     
     wherein, in Formulae 5-1 to 5-79, 
     Y 31  may be O, S, C(Z 33 )(Z 34 ), N(Z 35 ), or Si(Z 36 )(Z 37 ), 
     Z 31  to Z 37  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 31 )(Q 32 )(Q 33 ), 
     Z 33  and Z 34  may optionally be bound to form a substituted or unsubstituted C 5 -C 30  carbocyclic group or a substituted or unsubstituted C 1 -C 30  heterocyclic group, 
     e2 may be an integer from 0 to 2; when e2 is 2, at least two Z 31  groups may be identical to or different from each other, and at least two Z 32  groups may be identical to or different from each other, 
     e3 may be an integer from 0 to 3; when e3 is 2 or greater, at least two Z 31  groups (in (Z 31 ) e3 ) may be identical to or different from each other, and at least two Z 32  groups (in (Z 32 ) e3 ) may be identical to or different from each other, 
     e4 may be an integer from 0 to 4; when e4 is 2 or greater, at least two Z 31  groups (in (Z 31 ) e4 ) may be identical to or different from each other, and at least two Z 32  groups (in (Z 32 ) e4 ) may be identical to or different from each other, 
     e5 may be an integer from 0 to 5; when e5 is 2 or greater, at least two Z 31  groups (in (Z 31 ) e5 ) may be identical to or different from each other, and at least two Z 32  groups (in (Z 32 ) e5 ) may be identical to or different from each other, 
     e6 may be an integer from 0 to 6; when e6 is 2 or greater, at least two Z 31  groups (in (Z 31 ) e6 ) may be identical to or different from each other, and at least two Z 32  groups (in (Z 32 ) e6 ) may be identical to or different from each other, 
     e7 may be an integer from 0 to 7; when e7 is 2 or greater, at least two Z 31  groups may be identical to or different from each other, 
     e9 may be an integer from 0 to 9; when e9 is 2 or greater, at least two Z 31  groups may be identical to or different from each other, and 
     * indicates a binding site to an adjacent atom. 
     In some embodiments, in Formulae 1A and 1B, R 1  and R 2  may each independently be selected from groups represented by Formulae 5-1 to 5-20, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, R 1  and R 2  may each independently be selected from groups represented by Formulae 5-1 to 5-3, 5-13 to 5-16, and 5-20, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 5-1 to 5-79, Z 31  to Z 37  may each independently be selected from hydrogen, deuterium, —F, a cyano group, a methyl group, an ethyl group, an n-propyl group, a tert-butyl group, a phenyl group, and a naphthyl group, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, R 1  and R 2  may each independently be selected from groups represented by Formulae 6-1 to 6-42, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     wherein, in Formulae 6-1 to 6-42, 
     “Ph” represents a phenyl group, and 
     * indicates a binding site to an adjacent atom. 
     In Formulae 1A and 1B, R 3  to R 12  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a C 1 -C 60  alkyl group, a C 1 -C 60  alkoxy group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), and —N(Q 1 )(Q 2 ); 
     a C 1 -C 60  alkyl group and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a cyano group, and a nitro group; and 
     a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, a methyl group, a methoxy group, a phenyl group, a naphthyl group, and a biphenyl group, but embodiments are not limited thereto. 
     In some embodiments, R 3  to R 12  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a methyl group, an ethyl group, a propyl group, an iso-propyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a ter-butyl group, a pentyl group, an iso-amyl group, a hexyl group, a phenyl group, and a biphenyl group, but embodiments are not limited thereto. 
     In Formulae 1A and 1B, b1 to b3 and b5 to b8 may each independently be an integer from 1 to 10, and b4 may be an integer from 1 to 3. 
     b1 indicates the number of R 1  groups; when b1 is 2 or greater, at least two R 1  groups may be identical to or different from each other. Descriptions for b2 to b8 may each be understood by referring to (may be the same as) the descriptions for b1 provided herein. 
     At least one substituent of the substituted C 5 -C 60  carbocyclic group, the substituted C 1 -C 60  heterocyclic group, the substituted C 1 -C 60  alkyl group, the substituted C 2 -C 60  alkenyl group, the substituted C 2 -C 60  alkynyl group, the substituted C 1 -C 60  alkoxy group, the substituted C 3 -C 10  cycloalkyl group, the substituted C 1 -C 10  heterocycloalkyl group, the substituted C 3 -C 10  cycloalkenyl group, the substituted C 1 -C 10  heterocycloalkenyl group, the substituted C 6 -C 60  aryl group, the substituted C 6 -C 60  aryloxy group, the substituted C 6 -C 60  arylthio group, the substituted C 1 -C 60  heteroaryl group, the substituted C 1 -C 60  heteroaryloxy group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from: 
     deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
     a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 11 )(Q 12 )(Q 13 ), —N(Q 11 )(Q 12 ), —B(Q 11 )(Q 12 ), —C(═O)(Q 11 ), —S(═O) 2 (Q 11 ), and —P(═O)(Q 11 )(Q 12 ); 
     a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group; 
     a C 3 -C 10  cycloalkyl group, a C 1 -C 60  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 60  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, a terphenyl group, —Si(Q 21 )(Q 22 )(Q 23 ), —N(Q 21 )(Q 22 ), —B(Q 21 )(Q 22 ), —C(═O)(Q 21 ), —S(═O) 2 (Q 21 ), and —P(═O)(Q 21 )(Q 22 ); and 
     —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     wherein Q 1  to Q 3 , Q 11  to Q 13 , Q 21  to Q 23 , and Q 31  to Q 33  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryl group substituted with a C 1 -C 60  alkyl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group. 
     In some embodiments, the amine-based compound represented by one of Formulae 1A and 1B may be represented by Formula 1C or 1D, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
     
     wherein, in Formulae 1C and 1D, 
     descriptions for X 1 , X 2 , L 1  to L 3 , a1 to a3, R 1  to R 12 , and b1 and b2 may be understood by referring to (may be the same as) the descriptions for those of Formulae 1A and 1B, 
     b4, b6, and b8 may each independently be an integer from 1 to 3, and 
     b3, b5, and b7 may each independently be an integer from 1 to 4. 
     In some embodiments, the compound represented by one of Formulae 1A and 1B may be represented by one of Formulae 1A-1 to 1A-4 and 1B-1 to 1B-16, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
     
     wherein, in Formulae 1A-1 to 1A-4 and 1B-1 to 1B-16, 
     descriptions for X 1 , X 2 , L 1  to L 3 , a1 to a3, R 1  to R 12 , and b1 and b2 may be understood by referring to (may be the same as) the descriptions for those of Formulae 1A and 1B, 
     b4, b6, and b8 may each independently be an integer from to 3, and 
     b3, b5, and b7 may each independently be an integer from 1 to 4. 
     In some embodiments, in Formulae 1A-1 to 1A-4 and 1B-1 to 1B-16, X 1  may be N-(L 1 ) a1 -(R 1 ) b1 , and X 2  may be O, S, or C(R 11 )(R 12 ), 
     X 1  may be O, and X 2  may be C(R 11 )(R 12 ), or 
     X 1  may be C(R 9 )(R 10 ), and X 2  may be C(R 11 )(R 12 ), but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A-1 to 1A-4 and 1B-1 to 1B-16, L 1  to L 3  may each independently be selected from a single bond and a benzene group; and 
     a benzene group substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a C 6 -C 20  aryl group, a C 1 -C 20  heteroaryl group, and —Si(Q 31 )(Q 32 )(Q 33 ), but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A-1 to 1A-4 and 1B-1 to 1B-16, R 1  and R 2  may each independently be selected from Formulae 6-1 to 6-42, but embodiments are not limited thereto. 
     In some embodiments, in Formulae 1A and 1B, R 9  and R 10  and/or R 11  and R 12  may be bound to each other to form a group represented by one of Formulae 7-1 to 7-3: 
     
       
         
         
             
             
         
       
     
     In Formulae 7-1 to 7-3, 
     Z 51  and Z 52  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a spiro-fluorene-benzofluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 31 )(Q 32 )(Q 33 ), 
     n1 may be an integer from 1 to 8, 
     n2 may be an integer from 1 to 10, 
     n3 and n4 may each independently be an integer from 1 to 4, and 
     * indicates a carbon atom bound to R 9  and R 10  or bound to R 11  and R 12 . 
     In some embodiments, the compound represented by one of Formulae 1A and 1B may be selected from Compounds 1 to 265, 267 to 284, 207A, 208A and 226A, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The amine-based compound represented by one of Formulae 1A and 1B has a structure in which nitrogen (N) is bound to a substituent represented by Formula 1A′, and thus the compound may have a molecular structure having a large steric hindrance. Accordingly, the amine-based compound may maintain optimum intermolecular density. Further, the amine-based compound may have excellent hole transportability due to the increased interaction of an unshared electron pair of oxygen (O), which is relatively sterically exposed: 
     
       
         
         
             
             
         
       
     
     Furthermore, the amine-based compound includes an amine group in a molecule. Thus, the amine-based compound may have a suitable energy level, as compared with a compound including at least two amine groups. Accordingly, the amine-based compound may have improved hole mobility due to reduced hole transport barrier and hole injection barrier. 
     Therefore, an electronic device, e.g., an organic light-emitting device, employing the amine-based compound may have a low driving voltage, high efficiency, and long lifespan. 
     Methods of synthesizing the amine-based compound represented by one of Formulae 1A and 1B should be readily apparent to those of ordinary skill in the art by referring to Examples described herein. 
     At least one of the amine-based compounds represented by one of Formulae 1A and 1B may be included between a pair of electrodes in an organic light-emitting device. In some embodiments, the amine-based compound may be included in at least one selected from a hole transport region, an electron transport region, and an emission layer. In some embodiments, the amine-based compound represented by one of Formulae 1A and 1B may be utilized as a material for forming a capping layer, which is on outer sides of a pair of electrodes in an organic light-emitting device. 
     Accordingly, there is provided an organic light-emitting device including a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode, wherein the organic layer includes an emission layer and at least one amine-based compound represented by one of Formulae 1A and 1B. 
     As used herein, the expression “(for example, the organic layer) including at least one amine-based compound” refers to that “(the organic layer) including an amine-based compound represented by one of Formulae 1A and 1B, or at least two different amine-based compounds represented by one of Formulae 1A and 1B”. 
     For example, the organic layer may include only Compound 1 as the amine-based compound. In this embodiment, Compound 1 may be included in the emission layer of the organic light-emitting device. In some embodiments, the organic layer may include Compounds 1 and 2 as the amine-based compounds. In this embodiment, Compounds 1 and 2 may be present in the same layer (for example, Compounds 1 and 2 may be both present in an emission layer), or in different layers (for example, Compound 1 may be present in an emission layer, and Compound 2 may be present in an electron transport layer). 
     In some embodiments, the first electrode may be an anode, the second electrode may be a cathode, and the organic layer may further include a hole transport region between the first electrode and the emission layer and an electron transport region between the emission layer and the second electrode, wherein the hole transport region may include a hole injection layer, a hole transport layer, an emission auxiliary layer, an electron blocking layer, or a combination thereof, and the electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof. 
     In some embodiments, the hole transport region may include the amine-based compound. 
     In some embodiments, the hole transport region may include a hole injection layer and a hole transport layer, wherein at least one of the hole injection layer and the hole transport layer may include the amine-based compound. 
     In some embodiments, the hole transport region may include a hole transport layer, wherein the hole transport layer may include the amine-based compound. 
     In some embodiments, the hole transport region may include a p-dopant, wherein the p-dopant may have the lowest unoccupied molecular orbital (LUMO) energy level of −3.5 electron Volts (eV) or less. 
     In some embodiments, the p-dopant may include at least one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound. 
     In some embodiments, the hole transport region may include a hole injection layer including the p-dopant. 
     In some embodiments, the emission layer may include at least one selected from a styryl-based compound, an anthracene-based compound, a pyrene-based compound, and a spiro-bifluorene-based compound. 
     The term “organic layer” as used herein refers to a single and/or a plurality of layers between the first electrode and the second electrode in an organic light-emitting device. A material included in the “organic layer” is not limited to an organic material. 
     Description of  FIG. 1   
       FIG. 1  illustrates a schematic cross-sectional view of an organic light-emitting device  10  according to an embodiment. The organic light-emitting device  10  may include a first electrode  110 , an organic layer  150 , and a second electrode  190 . 
     Hereinafter, the structure of the organic light-emitting device  10  according to an embodiment and a method of manufacturing an organic light-emitting device  10  according to an embodiment will be described in connection with  FIG. 1 . 
     First Electrode  110   
     In  FIG. 1 , a substrate may be additionally disposed under the first electrode  110  or above the second electrode  190 . The substrate may be a glass substrate or a plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance. 
     The first electrode  110  may be formed by vacuum-depositing or sputtering, onto the substrate, a material for forming the first electrode  110 . When the first electrode  110  is an anode, the material for the first electrode  110  may be selected from materials with a high work function to facilitate hole injection. 
     The first electrode  110  may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. When the first electrode  110  is a transmissive electrode, as a material for forming the first electrode  110 , indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO 2 ), zinc oxide (ZnO), and any combination thereof may be utilized, but embodiments are not limited thereto. When the first electrode  110  is a semi-transmissive electrode or a reflective electrode, as a material for forming the first electrode  110 , magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), and any combination thereof may be utilized, but embodiments are not limited thereto. 
     The first electrode  110  may have a single-layered structure, or a multi-layered structure including two or more layers. In some embodiments, the first electrode  110  may have a triple-layered structure of ITO/Ag/ITO, but embodiments are not limited thereto. 
     Organic Layer  150   
     The organic layer  150  may be on the first electrode  110 . The organic layer  150  may include an emission layer. 
     The organic layer  150  may further include a hole transport region between the first electrode  110  and the emission layer and an electron transport region between the emission layer and the second electrode  190 . 
     Hole Transport Region in Organic Layer  150   
     The hole transport region may have i) a single-layered structure including a single layer including a single material, ii) a single-layered structure including a single layer including a plurality of different materials, or iii) a multi-layered structure having a plurality of layers, each including a single or a plurality of different materials. 
     The hole transport region may include at least one selected from a hole injection layer, a hole transport layer, an emission auxiliary layer, and an electron blocking layer. 
     For example, the hole transport region may have a single-layered structure including a single layer including a plurality of different materials or a multi-layered structure, e.g., a structure of hole injection layer/hole transport layer, a structure of hole injection layer/hole transport layer/emission auxiliary layer, a structure of hole injection layer/emission auxiliary layer, a structure of hole transport layer/emission auxiliary layer, or a structure of hole injection layer/hole transport layer/electron blocking layer, wherein layers of each structure are sequentially stacked on the first electrode  110  in each stated order, but embodiments are not limited thereto. 
     The hole transport region may include the amine-based compound represented by one of Formulae 1A and 1B. 
     The hole transport region may include, in addition to the amine-based compound represented by one of Formulae 1A and 1B, at least one selected from m-MTDATA, TDATA, 2-TNATA, NPB (NPD), β-NPB, TPD, spiro-TPD, spiro-NPB, methylated-NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), poly(3,4-ethylened ioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (PANI/CSA), (polyaniline)/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201, and a compound represented by Formula 202: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In Formulae 201 and 202, 
     L 201  to L 204  may each independently be selected from a substituted or unsubstituted C 3 -C 10  cycloalkylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkylene group, a substituted or unsubstituted C 3 -C 10  cycloalkenylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenylene group, a substituted or unsubstituted C 6 -C 60  arylene group, a substituted or unsubstituted C 1 -C 60  heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, 
     L 205  may be selected from *—O—*′, *—S—*′, *—N(Q 201 )-*′, a substituted or unsubstituted C 1 -C 20  alkylene group, a substituted or unsubstituted C 2 -C 20  alkenylene group, a substituted or unsubstituted C 3 -C 10  cycloalkylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkylene group, a substituted or unsubstituted C 3 -C 10  cycloalkenylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenylene group, a substituted or unsubstituted C 6 -C 60  arylene group, a substituted or unsubstituted C 1 -C 60  heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, 
     xa1 to xa4 may each independently be an integer from 0 to 3, 
     xa5 may be an integer from 1 to 10, and 
     R 201  to R 204  and Q 201  may each independently be selected from a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. 
     In some embodiments, in Formula 202, R 201  and R 202  may optionally be linked to each other via a single bond, a dimethyl-methylene group, or a diphenyl-methylene group, and R 203  and R 204  may optionally be linked to each other via a single bond, a dimethyl-methylene group, or a diphenyl-methylene group. 
     In one embodiment, in Formulae 201 and 202, L 201  to L 205  may each independently be selected from 
     a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an indacenylene group, an acenaphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a rubicenylene group, a coronenylene group, an ovalenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, and a pyridinylene group; and 
     a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an indacenylene group, an acenaphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a rubicenylene group, a coronenylene group, an ovalenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, and a pyridinylene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a phenyl group substituted with a C 1 -C 10  alkyl group, a phenyl group substituted with —F, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, —Si(Q 31 )(Q 32 )(Q 33 ), and —N(Q 31 )(Q 32 ), 
     wherein Q 31  to Q 33  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group. 
     In one or more embodiments, xa1 to xa4 may each independently be 0, 1, or 2. 
     In one or more embodiments, xa5 may be 1, 2, 3, or 4. 
     In one or more embodiments, R 201  to R 204  and Q 201  may each independently be selected from a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl group; and 
     a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a phenyl group substituted with a C 1 -C 10  alkyl group, a phenyl group substituted with —F, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, —Si(Q 31 )(Q 32 )(Q 33 ), and —N(Q 31 )(Q 32 ), 
     wherein descriptions for Q 31  to Q 33  may be understood by referring to (may be the same as) the descriptions for those provided herein. 
     In one or more embodiments, in Formula 201, at least one of R 201  to R 203  may each independently be selected from 
     a fluorenyl group, a spiro-bifluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and 
     a fluorenyl group, a spiro-bifluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a phenyl group substituted with a C 1 -C 10  alkyl group, a phenyl group substituted with —F, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, but embodiments are not limited thereto. 
     In one or more embodiments, in Formula 202, i) R 201  may be linked to R 202  via a single bond, and/or ii) R 203  may be linked to R 204  via a single bond. 
     In one or more embodiments, in Formula 202, at least one of R 201  to R 204  may be selected from 
     a carbazolyl group; and 
     a carbazolyl group substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a phenyl group substituted with a C 1 -C 10  alkyl group, a phenyl group substituted with —F, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, but embodiments are not limited thereto. 
     The compound represented by Formula 201 may be represented by Formula 201A: 
     
       
         
         
             
             
         
       
     
     In some embodiments, the compound represented by Formula 201 may be represented by Formula 201A(1), but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
     
     In some embodiments, the compound represented by Formula 201 may be represented by Formula 201A-1, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
     
     The compound represented by Formula 202 may be represented by Formula 202A: 
     
       
         
         
             
             
         
       
     
     In some embodiments, the compound represented by Formula 202 may be represented by Formula 202A-1: 
     
       
         
         
             
             
         
       
     
     In Formulae 201A, 201A(1), 201A-1, 202A, and 202A-1, 
     descriptions for L 201  to L 203 , xa1 to xa3, xa5, and R 202  to R 204  may each be understood by referring to (may be the same as) the descriptions for those provided herein, 
     descriptions for R 211  and R 212  may each be understood by referring to (may be the same as) the descriptions for those for R 203  provided herein, and 
     R 213  to R 217  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a phenyl group substituted with a C 1 -C 10  alkyl group, a phenyl group substituted with —F, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl group. 
     The hole transport region may include at least one compound selected from Compounds HT1 to HT39, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The thickness of the hole transport region may be in a range of about 100 (Angstroms) Å to about 10,000 Å, and in some embodiments, about 100 Å to about 1,000 Å. When the hole transport region includes at least one of a hole injection layer and a hole transport layer, a thickness of the hole injection layer may be in a range of about 100 Å to about 9,000 Å, for example, about 100 Å to about 1,000 Å, and a thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, for example, about 100 Å to about 1,500 Å. When the thicknesses of the hole transport region, the hole injection layer, and the hole transport layer are within the above-described ranges, excellent hole transport characteristics may be obtained without a substantial increase in driving voltage. 
     The emission auxiliary layer may increase light emission efficiency by compensating for an optical resonance distance according to the wavelength of light emitted by an emission layer. The electron blocking layer may reduce or eliminate the flow of electrons from an electron transport region. The emission auxiliary layer and the electron blocking layer may include the aforementioned materials. 
     p-Dopant 
     The hole transport region may include a charge generating material as well as the aforementioned materials, to improve conductive properties of the hole transport region. The charge generating material may be substantially homogeneously or non-homogeneously dispersed in the hole transport region. 
     The charge generating material may include, for example, a p-dopant. 
     In some embodiments, the LUMO energy level of the p-dopant may be about −3.5 eV or less. 
     The p-dopant may include at least one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound, but embodiments are not limited thereto. 
     In some embodiments, the p-dopant may include: 
     a quinone derivative, such as tetracyanoquinodimethane (TCNQ) or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ); 
     a metal oxide, such as tungsten oxide or molybdenum oxide; 
     1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (HAT-CN); and 
     a compound represented by Formula 221, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
     
     In Formula 221, 
     R 221  to R 223  may each independently be selected from a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, provided that at least one of R 221  to R 223  may include at least one substituent selected from a cyano group, —F, —Cl, —Br, —I, a C 1 -C 20  alkyl group substituted with —F, a C 1 -C 20  alkyl group substituted with —Cl, a C 1 -C 20  alkyl group substituted with —Br, and a C 1 -C 20  alkyl group substituted with —I. 
     Emission Layer in Organic Layer  150   
     When the organic light-emitting device  10  is a full color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, or a blue emission layer, according to a sub-pixel. In some embodiments, the emission layer may have a stacked structure. The stacked structure may include two or more layers selected from a red emission layer, a green emission layer, and a blue emission layer. The two or more layers may be in direct contact with each other. Alternatively, the two or more layers may be separated from each other. In one or more embodiments, the emission layer may include two or more materials. The two or more materials may include a red light-emitting material, a green light-emitting material, or a blue light-emitting material. The two or more materials may be mixed with each other in a single layer. The two or more materials mixed with each other in the single layer may emit white light. 
     The emission layer may include a host and a dopant. The dopant may include at least one of a fluorescent dopant and a phosphorescent dopant. 
     The amount of the dopant in the emission layer may be, in general, in a range of about 0.01 parts to about 15 parts by weight based on 100 parts by weight of the host, but embodiments are not limited thereto. 
     The thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å, and in some embodiments, about 200 Å to about 600 Å. When the thickness of the emission layer is within the above-described ranges, improved luminescence characteristics may be obtained without a substantial increase in driving voltage. 
     Host in Emission Layer 
     The host may include a compound represented by Formula 301: 
       [Ar 301 ] xb11 -[(L 301 ) xb1 -R 301 ] xb21   Formula 301
 
     wherein, in Formula 301, 
     Ar 301  may be a substituted or unsubstituted C 5 -C 60  carbocyclic group or a substituted or unsubstituted C 1 -C 60  heterocyclic group, 
     xb11 may be 1, 2, or 3, 
     L 301  may be selected from a substituted or unsubstituted C 3 -C 10  cycloalkylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkylene group, a substituted or unsubstituted C 3 -C 10  cycloalkenylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenylene group, a substituted or unsubstituted C 6 -C 60  arylene group, a substituted or unsubstituted C 1 -C 60  heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, 
     xb1 may be an integer from 0 to 5, 
     R 301  may be selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a substituted or unsubstituted C 1 -C 60  alkyl group, a substituted or unsubstituted C 2 -C 60  alkenyl group, a substituted or unsubstituted C 2 -C 60  alkynyl group, a substituted or unsubstituted C 1 -C 60  alkoxy group, a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 301 )(Q 302 )(Q 303 ), —N(Q 301 )(Q 302 ), —B(Q 301 )(Q 302 ), —C(═O)(Q 301 ), —S(═O) 2 (Q 301 ), and —P(═O)(Q 301 )(Q 302 ), 
     xb21 may be an integer from 1 to 5, 
     wherein Q 301  to Q 303  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group, but embodiments are not limited thereto. 
     In some embodiments, Ar 301  in Formula 301 may be selected from 
     a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, a dibenzofuran group, and a dibenzothiophene group; and 
     a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, a dibenzofuran group, and a dibenzothiophene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     wherein Q 31  to Q 33  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group, but embodiments are not limited thereto. 
     When xb11 in Formula 301 is 2 or greater, at least two Ar 301  groups may be linked via a single bond. 
     In one or more embodiments, the compound represented by Formula 301 may be represented by Formula 301-1 or 301-2: 
     
       
         
         
             
             
         
       
     
     In Formulae 301-1 to 301-2, 
     A 301  to A 304  may each independently be selected from a benzene group, a naphthalene group, a phenanthrene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a pyridine group, a pyrimidine group, an indene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, an indole group, a carbazole group, a benzocarbazole group, a dibenzocarbazole group, a furan group, a benzofuran group, a dibenzofuran group, a naphthofuran group, a benzonaphthofuran group, a dinaphthofuran group, a thiophene group, a benzothiophene group, a dibenzothiophene group, a naphthothiophene group, a benzonapthothiophene group, and a dinaphthothiophene group, 
     X 301  may be O, S, or N—[(L 304 ) xb4 -R 304 ], 
     R 311  to R 314  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     xb22 and xb23 may each independently be 0, 1, or 2, 
     descriptions for L 301 , xb1, R 301 , and Q 31  to Q 33  may each independently be understood by referring to (may be the same as) the descriptions for those provided herein, 
     descriptions for L 302  to L 304  may be understood by referring to (may be the same as) those for L 301  provided herein, 
     descriptions for xb2 to xb4 may each independently be understood by referring to (may be the same as) those for xb1 provided herein, and 
     descriptions for R 302  to R 304  may each independently be understood by referring to (may be the same as) those for R 301  provided herein. 
     In some embodiments, in Formulae 301, 301-1, and 301-2, L 301  to L 304  may each independently be selected from 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, a pyridinylene group, an imidazolylene group, a pyrazolylene group, a thiazolylene group, an isothiazolylene group, an oxazolylene group, an isoxazolylene group, a thiadiazolylene group, an oxadiazolylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a triazinylene group, a quinolinylene group, an isoquinolinylene group, a benzoquinolinylene group, a phthalazinylene group, a naphthyridinylene group, a quinoxalinylene group, a quinazolinylene group, a cinnolinylene group, a phenanthridinylene group, an acridinylene group, a phenanthrolinylene group, a phenazinylene group, a benzimidazolylene group, an isobenzothiazolylene group, a benzoxazolylene group, an isobenzoxazolylene group, a triazolylene group, a tetrazolylene group, an imidazopyridinylene group, an imidazopyrimidinylene group, and an azacarbazolylene group; and 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, a pyridinylene group, an imidazolylene group, a pyrazolylene group, a thiazolylene group, an isothiazolylene group, an oxazolylene group, an isoxazolylene group, a thiadiazolylene group, an oxadiazolylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a triazinylene group, a quinolinylene group, an isoquinolinylene group, a benzoquinolinylene group, a phthalazinylene group, a naphthyridinylene group, a quinoxalinylene group, a quinazolinylene group, a cinnolinylene group, a phenanthridinylene group, an acridinylene group, a phenanthrolinylene group, a phenazinylene group, a benzimidazolylene group, an isobenzothiazolylene group, a benzoxazolylene group, an isobenzoxazolylene group, a triazolylene group, a tetrazolylene group, an imidazopyridinylene group, an imidazopyrimidinylene group, and an azacarbazolylene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an azacarbazolyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     wherein descriptions for Q 31  to Q 33  may each independently be understood by referring to (may be the same as) the descriptions for those provided herein. 
     In some embodiments, in Formulae 301, 301-1, and 301-2, R 301  to R 304  may each independently be selected from 
     a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and an azacarbazolyl group; and 
     a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and an azacarbazolyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an azacarbazolyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     wherein descriptions for Q 31  to Q 33  may each independently be understood by referring to (may be the same as) the descriptions for those provided herein. 
     In some embodiments, the host may include an alkaline earth metal complex. For example, the host may include a beryllium (Be) complex, e.g., Compound H55, a magnesium (Mg) complex, or a zinc (Zn) complex. 
     The host may include at least one selected from 9,10-di(2-naphthyl)anthracene (ADN), 2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN), 9,10-di-(2-naphthyl)-2-t-butyl-anthracene (TBADN), 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), 1,3-di-9-carbazolylbenzene (mCP), 1,3,5-tri(carbazol-9-yl)benzene (TCP), and Compounds H1 to H55, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Phosphorescent Dopant Included in Emission Layer of Organic Layer  150   
     The phosphorescent dopant may include an organic metal complex represented by Formula 401: 
     
       
         
         
             
             
         
       
     
     In Formulae 401 and 402, 
     M may be selected from iridium (Ir), platinum (Pt), palladium (Pd), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), rhodium (Rh), and thulium (Tm), 
     L 401  may be selected from ligands represented by Formula 402, xc1 may be an integer selected from 1, 2, and 3; when xc1 is two or greater, at least two L 401  groups may be identical to or different from each other, 
     L 402  may be an organic ligand, xc2 may be an integer from 0 to 4; when xc2 is 2 or greater, at least two L 402  groups may be identical to or different from each other, 
     X 401  to X 404  may each independently be nitrogen or carbon, 
     X 401  and X 403  may be linked via a single bond or a double bond, X 402  and X 404  may be linked via a single bond or a double bond, 
     A 401  and A 402  may each independently be a C 5 -C 60  carbocyclic group or a C 1 -C 60  heterocyclic group, 
     X 405  may be a single bond, *—O—*′, *—S—*′, *—C(═O)—*′, *—N(Q 411 )-*′, * —C(Q 411 )(Q 412 )-*′, *—C(Q 411 )=C(Q 412 )-*′, *—C(Q 411 )=*′, or *═C═*′, wherein Q 411  and Q 412  may each independently be hydrogen, deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, 
     X 406  may be a single bond, O, or S, 
     R 401  and R 402  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a substituted or unsubstituted C 1 -C 20  alkyl group, a substituted or unsubstituted C 1 -C 20  alkoxy group, a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 401 )(Q 402 )(Q 403 ), —N(Q 401 )(Q 402 ), —B(Q 401 )(Q 402 ), —C(═O)(Q 401 ), —S(═O) 2 (Q 401 ), and —P(═O)(Q 401 )(Q 402 ), wherein Q 401  to Q 403  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a C 6 -C 20  aryl group, and a C 1 -C 20  heteroaryl group, 
     xc11 and xc12 may each independently be an integer from 0 to 10, and 
     * and *′ in Formula 402 each indicate a binding site to M in Formula 401. 
     In one embodiment, A 401  and A 402  in Formula 402 may each independently be selected from a benzene group, a naphthalene group, a fluorene group, a spiro-bifluorene group, an indene group, a pyrrole group, a thiophene group, a furan group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a quinoxaline group, a quinazoline group, a carbazole group, a benzimidazole group, a benzofuran group, a benzothiophene group, an isobenzothiophene group, a benzoxazole group, an isobenzoxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a dibenzofuran group, and a dibenzothiophene group. 
     In one or more embodiments, in Formula 402, i) X 401  may be nitrogen, and X 402  may be carbon, or ii) X 401  and X 402  may each be nitrogen. 
     In one or more embodiments, in Formula 402, R 401  and R 402  may each independently be selected from 
     hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, and a C 1 -C 20  alkoxy group; 
     a C 1 -C 20  alkyl group and a C 1 -C 20  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a phenyl group, a naphthyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornanyl group, and a norbornenyl group; 
     a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornanyl group, a norbornenyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; 
     a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornanyl group, a norbornenyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and 
     —Si(Q 401 )(Q 402 )(Q 403 ), —N(Q 401 )(Q 402 ), —B(Q 401 )(Q 402 ), —C(═O)(Q 401 ), —S(═O) 2 (Q 401 ) and —P(═O)(Q 401 )(Q 402 ), 
     wherein Q 401  to Q 403  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, and a naphthyl group, but embodiments are not limited thereto. 
     In one or more embodiments, when xc1 in Formula 401 is 2 or greater, two A 401 (s) in at least two L 401 (s) may optionally be linked to each other via X 407 , which is a linking group; or two A 402 (S) in at least two L 401 (s) may optionally be linked to each other via X 408 , which is a linking group (see Compounds PD1 to PD4 and PD7). X 407  and X 408  may each independently be selected from a single bond, *—O—*′, *—S—*′, *—C(═O)—*′, *—N(Q 413 )-*′, *—C(Q 413 )(Q 414 )-*′, and *—C(Q 413 )=C(Q 414 )-*′, wherein Q 413  and Q 414  may each independently be hydrogen, deuterium, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, but embodiments are not limited thereto. 
     L 402  in Formula 401 may be any suitable monovalent, divalent, or trivalent organic ligand. In some embodiments, L 402  may be selected from halogen, diketone (e.g., acetylacetonate), a carboxylic acid (e.g., picolinate), —C(═O), isonitrile, —CN, and phosphorus (e.g., phosphine or phosphite), but embodiments are not limited thereto. 
     In some embodiments, the phosphorescent dopant may include, for example, at least one selected from Compounds PD1 to PD25, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Fluorescent Dopant in Emission Layer 
     The fluorescent dopant may include an arylamine compound or a styrylamine compound. 
     The host may include a compound represented by Formula 501: 
     
       
         
         
             
             
         
       
     
     In Formula 501, 
     Ar 501  may be a substituted or unsubstituted C 5 -C 60  carbocyclic group or a substituted or unsubstituted C 1 -C 60  heterocyclic group, 
     L 501  to L 503  may be each independently selected from a substituted or unsubstituted C 3 -C 10  cycloalkylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkylene group, a substituted or unsubstituted C 3 -C 10  cycloalkenylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenylene group, a substituted or unsubstituted C 6 -C 60  arylene group, a substituted or unsubstituted C 1 -C 60  heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, 
     xd1 to xd3 may each independently be an integer from 0 to 3, 
     R 501  and R 502  may each independently be selected from a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and 
     xd4 may be an integer from 1 to 6. 
     In some embodiments, Ar 501  in Formula 501 may be selected from 
     a naphthalene group, a heptalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, and an indenophenanthrene group; and 
     a naphthalene group, a heptalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, and an indenophenanthrene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group. 
     In one or more embodiments, in Formula 501, L 501  to L 503  may each independently be selected from 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, and a pyridinylene group; and 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, and a pyridinylene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl group. 
     In one or more embodiments, in Formula 501, R 501  and R 502  may each independently be selected from 
     a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl group; and 
     a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, and a pyridinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, and —Si(Q 31 )(Q 32 )(Q 33 ), 
     wherein Q 31  to Q 33  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group. 
     In one or more embodiments, xd4 in Formula 501 may be 2, but embodiments are not limited thereto. 
     In some embodiments, the fluorescent dopant may be selected from Compounds FD1 to FD22: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In some embodiments, the fluorescent dopant may be selected from the following compounds, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
     
     Electron Transport Region in Organic Layer  150   
     The electron transport region may have i) a single-layered structure including a single layer including a single material, ii) a single-layered structure including a single layer including a plurality of different materials, or iii) a multi-layered structure having a plurality of layers including a plurality of different materials. 
     The electron transport region may include at least one selected from a buffer layer, a hole blocking layer, an electron control layer, an electron transport layer, and an electron injection layer, but embodiments are not limited thereto. 
     In some embodiments, the electron transport region may have a structure of an electron transport layer/electron injection layer, a structure of a hole blocking layer/electron transport layer/electron injection layer, a structure of an electron control layer/electron transport layer/electron injection layer, or a structure of a buffer layer/electron transport layer/electron injection layer, wherein layers of each structure are sequentially stacked on the emission layer in each stated order, but embodiments are not limited thereto. 
     The electron transport region, e.g., a buffer layer, a hole blocking layer, an electron control layer, or an electron transport layer in the electron transport region, may include a metal-free compound. The metal-free compound may include at least one π electron-depleted nitrogen-containing ring. 
     The term “π electron-depleted nitrogen-containing ring” as used herein refers to a C 1 -C 60  heterocyclic group having at least one *—N═*′ moiety as a ring-forming moiety. 
     For example, the “π electron-depleted nitrogen-containing ring” may be i) a 5-membered to 7-membered heteromonocyclic group having at least one *—N═*′ moiety, ii) a heteropolycyclic group in which two or more 5-membered to 7-membered heteromonocyclic groups, each having at least one *—N═*′ moiety, are condensed, or iii) a heteropolycyclic group in which at least one 5-membered to 7-membered heteromonocyclic group, having at least one *—N═*′ moiety, is condensed with at least one C 5 -C 60  carbocyclic group. 
     Examples of the π electron-depleted nitrogen-containing ring may include an imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isoxazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, an indazole, a purine, a quinoline, an isoquinoline, a benzoquinoline, a phthalazine, a naphthyridine, a quinoxaline, a quinazoline, a cinnoline, a phenanthridine, an acridine, a phenanthroline, a phenazine, a benzimidazole, an iso-benzothiazole, a benzoxazole, an isobenzoxazole, a triazole, a tetrazole, an oxadiazole, a triazine, a thiadiazole, an imidazopyridine, an imidazopyrimidine, and an azacarbazole, but embodiments are not limited thereto. 
     In some embodiments, the electron transport region may include a compound represented by Formula 601: 
       [Ar 601 ] xe11 -[(L 601 ) xe1 -R 601 ] xe21   Formula 601
 
     wherein, in Formula 601, 
     Ar 601  may be a substituted or unsubstituted C 5 -C 60  carbocyclic group or a substituted or unsubstituted C 1 -C 60  heterocyclic group, 
     xe11 may be 1, 2, or 3, 
     L 601  may be selected from a substituted or unsubstituted C 3 -C 10  cycloalkylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkylene group, a substituted or unsubstituted C 3 -C 10  cycloalkenylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenylene group, a substituted or unsubstituted C 6 -C 60  arylene group, a substituted or unsubstituted C 1 -C 60  heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, 
     xe1 may be an integer from 0 to 5, 
     R 601  may be selected from a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 601 )(Q 602 )(Q 603 ), —C(═O)(Q 601 ), —S(═O) 2 (Q 601 ), and —P(═O)(Q 601 )(Q 602 ), 
     wherein Q 601  to Q 603  may each independently be a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, and 
     xe21 may be an integer from 1 to 5. 
     In one embodiment, at least one of Ar 601  groups in the number of xe11 and R 601  groups in the number of xe21 may include the π electron-depleted nitrogen-containing ring. 
     In some embodiments, Ar 60 1 in Formula 601 may be selected from 
     a benzene group, a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, a dibenzofuran group, a dibenzothiophene group, a carbazole group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a phthalazine group, a naphthyridine group, a quinoxaline group, a quinazoline group, a cinnoline group, a phenanthridine group, an acridine group, a phenanthroline group, a phenazine group, a benzimidazole group, an iso-benzothiazole group, a benzoxazole group, an isobenzoxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a thiadiazole group, an imidazopyridine group, an imidazopyrimidine group, and an azacarbazole group; and 
     a benzene group, a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, a dibenzofuran group, a dibenzothiophene group, a carbazole group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, an indazole group, a purine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a phthalazine group, a naphthyridine group, a quinoxaline group, a quinazoline group, a cinnoline group, a phenanthridine group, an acridine group, a phenanthroline group, a phenazine group, a benzimidazole group, an iso-benzothiazole group, a benzoxazole group, an isobenzoxazole group, a triazole group, a tetrazole group, an oxadiazole group, a triazine group, a thiadiazole group, an imidazopyridine group, an imidazopyrimidine group, and an azacarbazole group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), 
     wherein Q 31  to Q 33  may each independently be selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group. 
     When xe11 in Formula 601 is 2 or greater, at least two Ar 601  groups may be linked via a single bond. 
     In one or more embodiments, Ar 601  in Formula 601 may be an anthracene group. 
     In some embodiments, the compound represented by Formula 601 may be represented by Formula 601-1: 
     
       
         
         
             
             
         
       
     
     In Formula 601-1, 
     X 614  may be N or C(R 614 ), X 615  may be N or C(R 615 ), X 616  may be N or C(R 616 ), and at least one selected from X 614  to X 616  may be N, 
     descriptions for L 611  to L 613  may each independently be understood by referring to (may be the same as) the descriptions for those for L 601  provided herein, 
     descriptions for xe611 to xe613 may each independently be understood by referring to (may be the same as) the descriptions for those for xe1 provided herein, 
     descriptions for R 611  to R 613  may each independently be understood by referring to (may be the same as) the descriptions for those for R 601  provided herein, and 
     R 614  to R 616  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group. 
     In one embodiment, in Formulae 601 and 601-1, L 601  and L 611  to L 613  may each independently be selected from 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, a pyridinylene group, an imidazolylene group, a pyrazolylene group, a thiazolylene group, an isothiazolylene group, an oxazolylene group, an isoxazolylene group, a thiadiazolylene group, an oxadiazolylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a triazinylene group, a quinolinylene group, an isoquinolinylene group, a benzoquinolinylene group, a phthalazinylene group, a naphthyridinylene group, a quinoxalinylene group, a quinazolinylene group, a cinnolinylene group, a phenanthridinylene group, an acridinylene group, a phenanthrolinylene group, a phenazinylene group, a benzimidazolylene group, an isobenzothiazolylene group, a benzoxazolylene group, an isobenzoxazolylene group, a triazolylene group, a tetrazolylene group, an imidazopyridinylene group, an imidazopyrimidinylene group, and an azacarbazolylene group; and 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-bifluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a thiophenylene group, a furanylene group, a carbazolylene group, an indolylene group, an isoindolylene group, a benzofuranylene group, a benzothiophenylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a dibenzosilolylene group, a pyridinylene group, an imidazolylene group, a pyrazolylene group, a thiazolylene group, an isothiazolylene group, an oxazolylene group, an isoxazolylene group, a thiadiazolylene group, an oxadiazolylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a triazinylene group, a quinolinylene group, an isoquinolinylene group, a benzoquinolinylene group, a phthalazinylene group, a naphthyridinylene group, a quinoxalinylene group, a quinazolinylene group, a cinnolinylene group, a phenanthridinylene group, an acridinylene group, a phenanthrolinylene group, a phenazinylene group, a benzimidazolylene group, an isobenzothiazolylene group, a benzoxazolylene group, an isobenzoxazolylene group, a triazolylene group, a tetrazolylene group, an imidazopyridinylene group, an imidazopyrimidinylene group, and an azacarbazolylene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and an azacarbazolyl group, but embodiments are not limited thereto. 
     In one or more embodiments, in Formulae 601 and 601-1, xe1 and xe611 to xe613, may each independently be 0, 1, or 2. 
     In one or more embodiments, in Formulae 601 and 601-1, R 601  and R 611  to R 613  may each independently be selected from 
     a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and an azacarbazolyl group; 
     a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and an azacarbazolyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, an indolyl group, an isoindolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a pyridinyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a thiadiazolyl group, an oxadiazolyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzimidazolyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and an azacarbazolyl group; and 
     —S(═O) 2 (Q 601 ) and —P(═O)(Q 601 )(Q 602 ), 
     wherein descriptions for Q 601  and Q 602  may each independently be understood by referring to (may be the same as) the descriptions for those provided herein. 
     The electron transport region may include at least one compound selected from Compounds ET1 to ET36, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In some embodiments, the electron transport region may include at least one compound selected from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), Alq 3 , BAlq, 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ), and NTAZ: 
     
       
         
         
             
             
         
       
     
     The thicknesses of the buffer layer, the hole blocking layer, or the electron control layer may each independently be in a range of about 20 Å to about 1,000 Å, and in some embodiments, about 30 Å to about 300 Å. When the thicknesses of the buffer layer, the hole blocking layer or the electron control layer are within the above-described ranges, excellent hole blocking characteristics or excellent electron controlling characteristics may be obtained without a substantial increase in driving voltage. 
     The thickness of the electron transport layer may be in a range of about 100 Å to about 1,000 Å, and in some embodiments, about 150 Å to about 500 Å. When the thickness of the electron transport layer is within the above-described ranges, excellent electron transport characteristics may be obtained without a substantial increase in driving voltage. 
     The electron transport region (e.g., the electron transport layer in the electron transport region) may further include, in addition to the materials described above, a material including metal (e.g., a metal ion). 
     The material including metal may include at least one selected from an alkali metal complex and an alkaline earth metal complex. The alkali metal complex may include a metal ion selected from a lithium (Li) ion, a sodium (Na) ion, a potassium (K) ion, a rubidium (Rb) ion, and a cesium (Cs) ion. The alkaline earth metal complex may include a metal ion selected from a beryllium (Be) ion, a magnesium (Mg) ion, a calcium (Ca) ion, an strontium (Sr) ion, and a barium (Ba) ion. Each ligand coordinated with the metal ion of the alkali metal complex and the alkaline earth metal complex may independently be selected from a hydroxyquinoline, a hydroxyisoquinoline, a hydroxybenzoquinoline, a hydroxyacridine, a hydroxyphenanthridine, a hydroxyphenyloxazole, a hydroxyphenylthiazole, a hydroxyphenyl oxadiazole, a hydroxyphenyl thiadiazole, a hydroxyphenyl pyridine, a hydroxyphenyl benzimidazole, a hydroxyphenyl benzothiazole, a bipyridine, a phenanthroline, and a cyclopentadiene, but embodiments are not limited thereto. 
     For example, the material including metal may include a Li complex. The Li complex may include, e.g., Compound ET-D1 (lithium quinolate, LiQ) or Compound ET-D2: 
     
       
         
         
             
             
         
       
     
     The electron transport region may include an electron injection layer that facilitates injection of electrons from the second electrode  190 . The electron injection layer may be in direct contact with the second electrode  190 . 
     The electron injection layer may have i) a single-layered structure including a single layer including a single material, ii) a single-layered structure including a single layer including a plurality of different materials, or iii) a multi-layered structure having a plurality of layers, each including a plurality of different materials. 
     The electron injection layer may include an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, a rare earth metal compound, an alkali metal complex, an alkaline earth metal complex, a rare earth metal complex, or a combination thereof. 
     The alkali metal may be selected from Li, Na, K, Rb, and Cs. In one embodiment, the alkali metal may be Li, Na, or Cs. In one or more embodiments, the alkali metal may be Li or Cs, but embodiments are not limited thereto. 
     The alkaline earth metal may be selected from Mg, Ca, Sr, and Ba. 
     The rare earth metal may be selected from Sc, Y, Ce, Tb, Yb, and Gd. 
     The alkali metal compound, the alkaline earth metal compound, and the rare earth metal compound may each independently be selected from oxides and halides (e.g., fluorides, chlorides, bromides, or iodines) of the alkali metal, the alkaline earth metal, and the rare earth metal, respectively. 
     The alkali metal compound may be selected from alkali metal oxides (such as Li 2 O, Cs 2 O, or K 2 O), and alkali metal halides (such as LiF, NaF, CsF, KF, LiI, NaI, CsI, Kl, or RbI). In one embodiment, the alkali metal compound may be selected from LiF, Li 2 O, NaF, LiI, NaI, CsI, and Kl, but embodiments are not limited thereto. 
     The alkaline earth metal compound may be selected from alkaline earth metal compounds such as BaO, SrO, CaO, Ba x Sr 1-x O (where 0&lt;x&lt;1), and Ba x Ca 1-x O (where 0&lt;x&lt;1). In one embodiment, the alkaline earth metal compound may be selected from BaO, SrO, and CaO, but embodiments are not limited thereto. 
     The rare earth metal compound may be selected from YbF 3 , ScF 3 , ScO 3 , Y 2 O 3 , Ce 2 O 3 , GdF 3 , and TbF 3 . In one embodiment, the rare earth metal compound may be selected from YbF 3 , ScF 3 , TbF 3 , YbI 3 , ScI 3 , and TbI 3 , but embodiments are not limited thereto. 
     The alkali metal complex, the alkaline earth metal complex, and the rare earth metal complex may each include ions of the above-described alkali metal, alkaline earth metal, and rare earth metal. Each ligand coordinated with the metal ion of the alkali metal complex, the alkaline earth metal complex, and the rare earth metal complex may independently be selected from a hydroxyquinoline, a hydroxyisoquinoline, a hydroxybenzoquinoline, a hydroxyacridine, a hydroxyphenanthridine, a hydroxyphenyl oxazole, a hydroxyphenyl thiazole, a hydroxyphenyl oxadiazole, a hydroxyphenyl thiadiazole, a hydroxyphenyl pyridine, a hydroxyphenyl benzimidazole, a hydroxyphenyl benzothiazole, a bipyridine, a phenanthroline, and a cyclopentadiene, but embodiments are not limited thereto. 
     The electron injection layer may include (e.g., consist of) an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, a rare earth metal compound, an alkali metal complex, an alkaline earth metal complex, a rare earth metal complex, or a combination thereof, as described above. In some embodiments, the electron injection layer may further include an organic material. When the electron injection layer further includes an organic material, the alkali metal, the alkaline earth metal, the rare earth metal, the alkali metal compound, the alkaline earth metal compound, the rare earth metal compound, the alkali metal complex, the alkaline earth metal complex, the rare earth metal complex, or a combination thereof may be homogeneously or non-homogeneously dispersed in a matrix including the organic material. 
     The thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, and in some embodiments, about 3 Å to about 90 Å. When the thickness of the electron injection layer is within the above-described ranges, excellent electron injection characteristics may be obtained without a substantial increase in driving voltage. 
     Second Electrode  190   
     The second electrode  190  may be on the organic layer  150 . In an embodiment, the second electrode  190  may be a cathode that is an electron injection electrode. In this embodiment, a material for forming the second electrode  190  may be a material having a low work function, for example, a metal, an alloy, an electrically conductive compound, or a combination thereof. 
     The second electrode  190  may include at least one selected from lithium (Li), silver (Ag), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), ITO, and IZO, but embodiments are not limited thereto. The second electrode  190  may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. 
     The second electrode  190  may have a single-layered structure, or a multi-layered structure including two or more layers. 
     Description of FIGS.  2  to  4   
     Referring to  FIG. 2 , an organic light-emitting device  20  has the structure of a first capping layer  210 , the first electrode  110 , the organic layer  150 , and the second electrode  190 , wherein the layers are sequentially stacked in this stated order. Referring to  FIG. 3 , an organic light-emitting device  30  has the structure of the first electrode  110 , the organic layer  150 , the second electrode  190 , and a second capping layer  220 , wherein the layers are sequentially stacked in this stated order. Referring to  FIG. 4 , an organic light-emitting device  40  has the structure of the first capping layer  210 , the first electrode  110 , the organic layer  150 , the second electrode  190 , and the second capping layer  220 , wherein the layers are stacked in this stated order. 
     The first electrode  110 , the organic layer  150 , and the second electrode  190  illustrated in  FIGS. 2 to 4  may be substantially the same as those illustrated in  FIG. 1 . 
     In the organic light-emitting devices  20  and  40 , light emitted from the emission layer in the organic layer  150  may pass through the first electrode  110  (which may be a semi-transmissive electrode or a transmissive electrode) and through the first capping layer  210  to the outside. In the organic light-emitting devices  30  and  40 , light emitted from the emission layer in the organic layer  150  may pass through the second electrode  190  (which may be a semi-transmissive electrode or a transmissive electrode) and through the second capping layer  220  to the outside. 
     The first capping layer  210  and the second capping layer  220  may improve the external luminescence efficiency based on the principle of constructive interference. 
     The first capping layer  210  and the second capping layer  220  may each independently be an organic capping layer including an organic material, an inorganic capping layer including an inorganic material, or a composite capping layer including an organic material and an inorganic material. 
     At least one of the first capping layer  210  and the second capping layer  220  may each independently include at least one material selected from carbocyclic compounds, heterocyclic compounds, amine-based compounds, porphine derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, alkali metal complexes, and alkaline earth metal complexes. The carbocyclic compound, the heterocyclic compound, and the amine-based compound may optionally be substituted with a substituent containing at least one element selected from O, N, S, Se, Si, F, Cl, Br, and I. In one embodiment, at least one of the first capping layer  210  and the second capping layer  220  may each independently include an amine-based compound. 
     In one or more embodiments, at least one of the first capping layer  210  and the second capping layer  220  may each independently include a compound represented by Formula 201 or a compound represented by Formula 202. 
     In one or more embodiments, at least one of the first capping layer  210  and the second capping layer  220  may each independently include a compound selected from Compounds HT28 to HT33 and Compound CP1 to CP5, but embodiments are not limited thereto: 
     
       
         
         
             
             
         
       
     
     Hereinbefore, the organic light-emitting device has been described with reference to  FIGS. 1 to 4 , but embodiments are not limited thereto. 
     The layers constituting the hole transport region, the emission layer, and the layers constituting the electron transport region may be formed in a specific region (e.g., in a respective region) utilizing one or more suitable methods, such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) deposition, ink-jet printing, laser printing, and/or laser-induced thermal imaging. 
     When the layers constituting the hole transport region, the emission layer, and/or the layers constituting the electron transport region are each formed by vacuum deposition, the vacuum deposition may be performed at a deposition temperature in a range of about 100° C. to about 500° C. at a vacuum degree in a range of about 10 −8  torr to about 10 −3  torr, and at a deposition rate in a range of about 0.01 Angstroms per second (Å/sec) to about 100 Å/sec, depending on the material to be included in each layer and the structure of each layer to be formed. 
     When the layers constituting the hole transport region, the emission layer, and/or the layers constituting the electron transport region are each formed by spin coating, the spin coating may be performed at a coating rate of about 2,000 revolutions per minute (rpm) to about 5,000 rpm and at a heat treatment temperature of about 80° C. to about 200° C., depending on the material to be included in each layer and the structure of each layer to be formed. 
     General Definitions of Substituents 
     The term “C 1 -C 60  alkyl group” as used herein refers to a linear or branched aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms. Examples thereof may include a methyl group, an ethyl group, a propyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an iso-amyl group, and a hexyl group. The term “C 1 -C 60  alkylene group” as used herein refers to a divalent group having substantially the same structure as the C 1 -C 60  alkyl group. 
     The term “C 2 -C 60  alkenyl group” as used herein refers to a hydrocarbon group having at least one carbon-carbon double bond in the middle or at the terminus of the C 2 -C 60  alkyl group. Examples thereof may include an ethenyl group, a propenyl group, and a butenyl group. The term “C 2 -C 60  alkenylene group” as used herein refers to a divalent group having substantially the same structure as the C 2 -C 60  alkenyl group. 
     The term “C 2 -C 60  alkynyl group” as used herein refers to a hydrocarbon group having at least one carbon-carbon triple bond in the middle or at the terminus of the C 2 -C 60  alkyl group. Examples thereof may include an ethynyl group and a propynyl group. The term “C 2-60  alkynylene group” as used herein refers to a divalent group having substantially the same structure as the C 2 -C 60  alkynyl group. 
     The term “C 1 -C 60  alkoxy group” as used herein refers to a monovalent group represented by —OA 101  (wherein A 101  is a C 1 -C 60  alkyl group). Examples thereof may include a methoxy group, an ethoxy group, and an isopropyloxy group. 
     The term “C 3 -C 10  cycloalkyl group” as used herein refers to a monovalent monocyclic saturated hydrocarbon group including 3 to 10 carbon atoms. Examples thereof may include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The term “C 3 -C 10  cycloalkylene group” as used herein refers to a divalent group having substantially the same structure as the C 3 -C 10  cycloalkyl group. 
     The term “C 1 -C 10  heterocycloalkyl group” as used herein refers to a monovalent monocyclic group including at least one heteroatom selected from N, O, Si, P, and S as a ring-forming atom and 1 to 10 carbon atoms. Examples thereof may include a 1,2,3,4-oxatriazolidinyl group, a tetrahydrofuranyl group, and a tetrahydrothiophenyl group. The term “C 1 -C 10  heterocycloalkylene group” as used herein refers to a divalent group having substantially the same structure as the C 1 -C 10  heterocycloalkyl group. 
     The term “C 3 -C 10  cycloalkenyl group” as used herein refers to a monovalent monocyclic group including 3 to 10 carbon atoms and at least one carbon-carbon double bond in its ring, wherein the molecular structure as a whole is non-aromatic. Examples thereof may include a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The term “C 3 -C 10  cycloalkenylene group” as used herein refers to a divalent group having substantially the same structure as the C 3 -C 10  cycloalkenyl group. 
     The term “C 1 -C 10  heterocycloalkenyl group” as used herein refers to a monovalent monocyclic group including at least one heteroatom selected from N, O, Si, P, and S as a ring-forming atom, 1 to 10 carbon atoms, and at least one double bond in its ring. Examples of the C 1 -C 10  heterocycloalkenyl group may include a 4,5-dihydro-1,2,3,4-oxatriazolyl group, a 2,3-dihydrofuranyl group, and a 2,3-dihydrothiophenyl group. The term “C 1 -C 10  heterocycloalkenylene group” as used herein refers to a divalent group having substantially the same structure as the C 1 -C 10  heterocycloalkenyl group. 
     The term “C 6 -C 60  aryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. The term “C 6 -C 60  arylene group” as used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Examples of the C 6 -C 60  aryl group may include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C 6 -C 60  aryl group and the C 6 -C 60  arylene group each independently include two or more rings, the respective rings may be fused. 
     The term “C 1 -C 60  heteroaryl group” as used herein refers to a monovalent group having a heterocyclic aromatic system having at least one heteroatom selected from N, O, Si, P, and S as a ring-forming atom and 1 to 60 carbon atoms. The term “C 1 -C 60  heteroarylene group” as used herein refers to a divalent group having a heterocyclic aromatic system having at least one heteroatom selected from N, O, Si, P, and S as a ring-forming atom and 1 to 60 carbon atoms. Examples of the C 1 -C 60  heteroaryl group may include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group. When the C 1 -C 60  heteroaryl group and the C 1 -C 60  heteroarylene group each independently include two or more rings, the respective rings may be fused. 
     The term “C 6 -C 60  aryloxy group” as used herein refers to a group represented by —OA 102  (where A 102  is a C 6 -C 60  aryl group). The term “C 6 -C 60  arylthio group” as used herein refers to a group represented by —SA 103  (where A 103  is a C 6 -C 60  aryl group). 
     The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group that has two or more rings condensed and only carbon atoms as ring forming atoms (e.g., 8 to 60 carbon atoms), wherein the entire molecular structure is non-aromatic. An example of the monovalent non-aromatic condensed polycyclic group may be a fluorenyl group. The term “divalent non-aromatic condensed polycyclic group” as used herein refers to a divalent group having substantially the same structure as the monovalent non-aromatic condensed polycyclic group. 
     The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group that has two or more condensed rings and at least one heteroatom selected from N, O, Si, P, and S, in addition to carbon atoms (e.g., 1 to 60 carbon atoms), as a ring-forming atom, wherein the entire molecular structure is non-aromatic. An example of the monovalent non-aromatic condensed heteropolycyclic group is a carbazolyl group. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein refers to a divalent group having substantially the same structure as the monovalent non-aromatic condensed heteropolycyclic group. 
     The term “C 5 -C 60  carbocyclic group” as used herein refers to a monocyclic group or a polycyclic group that includes 5 to 60 carbon atoms, in which the ring-forming atoms are only carbon atoms. The C 5 -C 60  carbocyclic group may be an aromatic carbocyclic group or a non-aromatic carbocyclic group. The term “C 5 -C 60  carbocyclic group” as used herein refers to a ring (e.g., a benzene group), a monovalent group (e.g., a phenyl group), or a divalent group (e.g., a phenylene group). In one or more embodiments, depending on the number of substituents connected to the C 5 -C 60  carbocyclic group, the C 5 -C 60  carbocyclic group may be a trivalent group or a quadrivalent group. 
     The term “C 1 -C 60  heterocyclic group” as used herein refers to a group having substantially the same structure as the C 5 -C 60  carbocyclic group, except that at least one heteroatom selected from N, O, Si, P, and S is used as a ring-forming atom, in addition to carbon atoms (e.g., 1 to 60 carbon atoms). 
     In the present specification, at least one substituent of the substituted C 5 -C 60  carbocyclic group, the substituted C 1 -C 60  heterocyclic group, the substituted C 3 -C 10  cycloalkylene group, the substituted C 1 -C 10  heterocycloalkylene group, the substituted C 3 -C 10  cycloalkenylene group, the substituted C 1 -C 10  heterocycloalkenylene group, the substituted C 6 -C 60  arylene group, the substituted C 1 -C 60  heteroarylene group, the substituted divalent non-aromatic condensed polycyclic group, the substituted divalent non-aromatic condensed heteropolycyclic group, the substituted C 1 -C 60  alkyl group, the substituted C 2 -C 60  alkenyl group, the substituted C 2 -C 60  alkynyl group, the substituted C 1 -C 60  alkoxy group, the substituted C 3 -C 10  cycloalkyl group, the substituted C 1 -C 10  heterocycloalkyl group, the substituted C 3 -C 10  cycloalkenyl group, the substituted C 1 -C 10  heterocycloalkenyl group, the substituted C 6 -C 60  aryl group, the substituted C 6 -C 60  aryloxy group, the substituted C 6 -C 60  arylthio group, the substituted C 1 -C 60  heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from: 
     deuterium (-D), —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
     a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 11 )(Q 12 )(Q 13 ), —N(Q 11 )(Q 12 ), —B(Q 11 )(Q 12 ), —C(═O)(Q 11 ), —S(═O) 2 (Q 11 ), and —P(═O)(Q 11 )(Q 12 ); 
     a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; 
     a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 21 )(Q 22 )(Q 23 ), —N(Q 21 )(Q 22 ), —B(Q 21 )(Q 22 ), —C(═O)(Q 21 ), —S(═O) 2 (Q 21 ), and —P(═O)(Q 21 )(Q 22 ); and 
     —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ) and —P(═O)(Q 31 )(Q 32 ), 
     wherein Q 11  to Q 13 , Q 21  to Q 23 , and Q 31  to Q 33  may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group. 
     The term “Ph” as used herein represents a phenyl group. The term “Me” as used herein represents a methyl group. The term “Et” as used herein represents an ethyl group. The term “ter-Bu” or “But” as used herein represents a tert-butyl group. The term “OMe” as used herein represents a methoxy group. 
     The term “biphenyl group” as used herein refers to a phenyl group substituted with a phenyl group. The “biphenyl group” belongs to “a substituted phenyl group” having a “C 6 -C 60  aryl group” as a substituent. 
     The term “terphenyl group” as used herein refers to a phenyl group substituted with a biphenyl group. The “terphenyl group” belongs to “a substituted phenyl group” having a “C 6 -C 60  aryl group substituted with a C 6 -C 60  aryl group” as a substituent. 
     The symbols * and *′ as used herein, unless defined otherwise, each indicate a binding site to an adjacent atom in the corresponding formula. 
     Hereinafter, compounds and an organic light-emitting device according to one or more embodiments will be described in more detail with reference to Synthesis Examples and Examples. The wording “B was utilized instead of A” used in describing Synthesis Examples means that an amount of B utilized was identical to an amount of A utilized in terms of molar equivalents. 
     Synthesis Examples 
     Synthesis Example 1: Synthesis of Compound 1 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 1-1 
     5 grams (g) of 1-bromodibenzo[b,d]furan (Intermediate (a)), 6.4 g of 9,9-dimethyl-9H-fluoren-2-amine (Intermediate (b)), 6.4 g of potassium tert-butoxide (K t OBu), 0.3 g of P(tBu) 3 , and 0.4 g of Pd 2  (dba) 3  were diluted in toluene, followed by stirring at a temperature of 100° C. under reflux. After a 20-hour lapse, the temperature was lowered to room temperature. Subsequently, the reaction was terminated utilizing water. An organic layer was extracted therefrom three times utilizing ethyl acetate. Then, the organic layer was dried utilizing anhydrous magnesium sulfate, followed by filtration under reduced pressure. The obtained residue was separated and purified through column chromatography to thereby obtain 6.5 g of Intermediate 1-1 (yield: 86%). The compound thus obtained was identified by liquid chromatography-mass spectrometry (LC-MS). C27H21NO: calc&#39;d: M+375.16 foun&#39;d: 375.26 
     (2) Synthesis of Compound 1 
     Compound 1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.8 g of Intermediate 1-1 was utilized instead of Intermediate (b), and 3.7 g of 3-iodo-9-phenyl-9H-carbazole (Intermediate (c)) was utilized instead of 1-bromodibenzo[b,d]furan (Intermediate (a)). 
     C45H32N2O: calc&#39;d: M+616.25 foun&#39;d: 616.35 
     Synthesis Example 2: Synthesis of Compound 2 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 2-1 
     8.2 g of Intermediate 2-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 8 g of Intermediate (d) was utilized instead of Intermediate (b) (yield: 82%). C 37 H25NO: calc&#39;d: M+ 499.19 foun&#39;d: 499.29 
     (2) Synthesis of Compound 2 
     Compound 2 was obtained in substantially the same manner as in Synthesis of Compound 1, except that 5 g of Intermediate 2-1 was utilized instead of Intermediate 1-1. C55H36N2O: calc&#39;d: M+ 740.28 foun&#39;d: 740.38 
     Synthesis Example 3: Synthesis of Compound 3 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 3-1 
     5.2 g of Intermediate 3-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 8 g of Intermediate (e) was utilized instead of Intermediate (b) (yield: 52%). C37H25NO: calc&#39;d: M+497.18 foun&#39;d: 497.28 
     (2) Synthesis of Compound 3 
     7.4 g of Compound 3 was obtained in substantially the same manner as in Synthesis of Compound 1, except that 5 g of Intermediate 3-1 was utilized instead of Intermediate 1-1 (yield: 75%). C55H36N2O: calc&#39;d: M+740.28 foun&#39;d: 740.38 
     Synthesis Example 4: Synthesis of Compound 4 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 4-1 
     5.1 g of Intermediate 4-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 4.9 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a), and 7.1 g of spiro[cyclopentane-1,9′-fluoren]-2′-amine was utilized instead of Intermediate (b) (yield: 64%). 
     C29H23NO: calc&#39;d: M+401.18 foun&#39;d: 401.20 
     (2) Synthesis of Compound 4 
     4.6 g of Compound 4 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 4 g of Intermediate 4-1 was utilized instead of Intermediate (b), and 3.7 g of 3-iodo-9-phenyl-9H-carbazole was utilized instead of 5 g of Intermediate (a) (yield: 72%). 
     C47H34N2O: calc&#39;d: M+647.27 foun&#39;d: 647.28 
       1 H NMR (500 MHz, CDCl 3 ) δ=8.22 (m, 1H), 7.79 (dd, 2H), 7.72 (dd, 1H), 7.67 (d, 1H), 7.54-7.14 (m, 17H), 6.95 (d, 1H), 6.90 (dd, 1H), 6.66 (dd, 1H), 6.54 (dd, 1H), 2.19-2.08 (m, 2H), 1.95-1.72 (m, 6H) 
     Synthesis Example 5: Synthesis of Compound 5 
     
       
         
         
             
             
         
       
     
     4.7 g of Compound 5 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.8 g of Intermediate 1-1 was utilized instead of Intermediate (b), and 3.4 g of 3-bromo-9-(4-fluorophenyl)-9H-carbazole was utilized instead of Intermediate (a) (yield: 75%). C45H31FN2O: calc&#39;d: M+634.24 foun&#39;d: 634.34 
     Synthesis Example 6: Synthesis of Compound 6 
     
       
         
         
             
             
         
       
     
     5.2 g of Compound 6 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 5 g of Intermediate 2-1 was utilized instead of Intermediate (b), and 3.4 g of 3-bromo-9-(4-fluorophenyl)-9H-carbazole was utilized instead of Intermediate (a) (yield: 68%). C55H35FN2O: calc&#39;d: M+758.27 foun&#39;d: 758.37 
     Synthesis Example 7: Synthesis of Compound 8 
     
       
         
         
             
             
         
       
     
     5 g of Compound 8 was obtained in substantially the same manner as in Synthesis of Compound 4, except that 4 g of Intermediate 4-1 and 3.9 g of 9-(4-fluorophenyl)-3-iodo-9H-carbazole were utilized (yield: 76%). 
     C47H33FN2O: calc&#39;d: M+660.26 foun&#39;d: 660.27 
       1 H NMR (500 MHz, CDCl 3 ) δ=8.22 (m, 1H), 7.79 (dd, 2H), 7.72 (dd, 1H), 7.67 (d, 1H), 7.48-7.23 (m, 13H), 7.18-7.14 (m, 1H), 7.09-7.04 (m, 2H), 6.95 (d, 1H), 6.90 (dd, 1H), 6.66 (dd, 1H), 6.54 (dd, 1H), 2.19-2.08 (m, 2H), 1.95-1.72 (m, 6H) 
     Synthesis Example 8: Synthesis of Compound 16 
     
       
         
         
             
             
         
       
     
     4.7 g of Compound 16 was obtained in substantially the same manner as in Synthesis of Compound 4, except that 4 g of Intermediate 4-1 and 4 g of 9-([1,1′-biphenyl]-4-yl)-3-bromo-9H-carbazole were utilized (yield: 66%). 
     C53H38N2O: calc&#39;d: M+718.30 foun&#39;d: 718.33 
       1 H NMR (500 MHz, CDCl 3 ) δ=8.22 (m, 1H), 7.79 (dd, 2H), 7.72 (dd, 1H), 7.67 (d, 1H), 7.63-7.59 (m, 2H), 7.57-7.23 (m, 18H), 7.18 (dt, 1H), 6.95 (d, 1H), 6.90 (dd, 1H), 6.66 (dd, 1H), 6.59 (dd, 1H), 2.19-2.08 (m, 2H), 1.95-1.72 (m, 6H) 
     Synthesis Example 9: Synthesis of Compound 21 
     
       
         
         
             
             
         
       
     
     4.3 g of Compound 21 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.8 g of Intermediate 1-1 was utilized instead of Intermediate (b), and 2.5 g of 2-bromodibenzo[b,d]furan was utilized instead of Intermediate (a) (yield: 80%). C45H31FN2O: calc&#39;d: M+541.20 foun&#39;d: 541.30 
     Synthesis Example 10: Synthesis of Compound 37 
     
       
         
         
             
             
         
       
     
     3.8 g of Compound 37 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.6 g of Intermediate 37-1 was utilized instead of Intermediate (b), and 3.7 g of Intermediate (c) was utilized instead of Intermediate (a) (yield: 76%). 
     C36H24N2O M+ calc&#39;d: 500.19 foun&#39;d: 500.29 
     Synthesis Example 11: Synthesis of Compound 93 
     
       
         
         
             
             
         
       
     
     5.1 g of Compound 93 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.8 g of Intermediate 1-1 was utilized instead of Intermediate (b), and 4 g of Intermediate 93-1 was utilized instead of Intermediate (a) (yield: 74%). 
     C51H36N2O M+ calc&#39;d: 692.28 foun&#39;d: 692.38 
     Synthesis Example 12: Synthesis of Compound 94 
     
       
         
         
             
             
         
       
     
     6.3 g of Compound 94 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 5 g of Intermediate 2-1 was utilized instead of Intermediate (b), and 4 g of Intermediate 93-1 was utilized instead of Intermediate (a) (yield: 77%). 
     C61H40N2O M+ calc&#39;d: 816.31 foun&#39;d: 816.41 
     Synthesis Example 13: Synthesis of Compound 95 
     
       
         
         
             
             
         
       
     
     6.1 g of Compound 95 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 5 g of Intermediate 3-1 was utilized instead of Intermediate (b), and 4 g of Intermediate 93-1 was utilized instead of Intermediate (a) (yield: 75%). 
     C61H38N2O M+ calc&#39;d: 814.30 foun&#39;d: 814.40 
     Synthesis Example 14: Synthesis of Compound 101 
     
       
         
         
             
             
         
       
     
     7.1 g of Compound 101 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.8 g of Intermediate 1-1 was utilized instead of Intermediate (b), and 4.2 g of Intermediate 101-1 was utilized instead of Intermediate (a) (yield: 75%). 
     C51H35FN2O M+ calc&#39;d: 710.27 foun&#39;d: 710.37 
     Synthesis Example 15: Synthesis of Compound 187 
     
       
         
         
             
             
         
       
     
     3.1 g of Compound 187 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.5 g of Intermediate 2-1 was utilized instead of Intermediate (b), and 4.2 g of Intermediate 101-1 was utilized instead of Intermediate Intermediate (a) (yield: 77%). 
     C62H39NO: calc&#39;d: M+813.30 foun&#39;d: 813.34 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.92-7.84 (m, 4H), 7.79 (m, 1H), 7.72 (dd, 1H), 7.61 (d, 1H), 7.58 (d, 1H), 7.48-7.41 (m, 5H), 7.36-7.28 (m, 3H), 7.21-7.06 (m, 14H), 6.92 (dd, 1H), 6.81-6.72 (m, 5H), 6.66 (dd, 1H), 6.57 (d, 1H), 6.43 (d, 1H) 
     Synthesis Example 16: Synthesis of Compound 188 
     
       
         
         
             
             
         
       
     
     3.3 g of Compound 188 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.5 g of Intermediate 3-1 was utilized instead of Intermediate (b), and 2 g of 2-bromo-9,9′-spirobi[fluorene] was utilized instead of Intermediate (a) (yield: 81%). 
     C62H37NO: calc&#39;d: M+811.29 foun&#39;d: 811.31 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.92 (dd, 4H), 7.89 (dd, 2H), 7.79 (td, 1H), 7.72 (dd, 1H), 7.61 (d, 2H), 7.48-7.41 (m, 7H), 7.36-7.26 (m, 3H), 7.21-7.15 (m, 6H), 6.92 (dd, 2H), 6.77-6.73 (m, 6H), 6.68 (dd, 1H), 6.43 (d, 2H) 
     Synthesis Example 17: Synthesis of Compound 204 
     
       
         
         
             
             
         
       
     
     3.8 g of Compound 204 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 5 g of Intermediate 2-1 was utilized instead of Intermediate (b), and 2.3 g of 2-bromo-1,1′-biphenyl was utilized instead of Intermediate (a) (yield: 58%). 
     C49H33NO: M+ calc&#39;d: 651.26 foun&#39;d: 651.36 
     Synthesis Example 18: Synthesis of Compound 210 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 210-1 
     3 g of Intermediate 210-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.5 g of [1,1′-biphenyl]-2-amine was utilized instead of Intermediate (b), and 2.5 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a) (yield: 91%). 
     C24H17NO: calc&#39;d: M+335.13 foun&#39;d: 335.14 
     (2) Synthesis of Compound 210 
     5.1 g of Compound 210 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3 g of Intermediate 210-1 was utilized instead of Intermediate (b), and 3.7 g of 2-bromo-9,9′-spirobi[fluorene] was utilized instead of Intermediate (a) (yield: 86%). 
     C49H31NO: calc&#39;d: M+649.24 foun&#39;d: 649.25 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.92 (dd, 2H), 7.89 (dd, 1H), 7.80 (d, 1H), 7.72 (d, 1H), 7.59-7.51 (m, 5H), 7.49-7.41 (m, 5H), 7.32-7.27 (m, 3H), 7.21-7.14 (m, 5H), 7.01 (t, 1H), 6.77-6.73 (m, 4H), 6.66 (dd, 1H), 6.61 (dd, 1H), 5.47 (d, 1H) 
     Synthesis Example 19: Synthesis of Compound 213 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 213-2 
     4.7 g of 2,7-dibromo-9,9′-spirobi[fluorene] and 3.4 g of phenyl boronic acid were diluted with 60 mL of tetrahydrofuran and 20 mL of water. 4.1 g of K 2 CO 3  and 580 mg of Pd(PPh 3 ) 4  were added dropwise thereto, followed by stirring at a temperature of 65° C. under reflux. Once the reaction was complete, the temperature was lowered to room temperature, and filtration was performed three times utilizing ethyl acetate under reduced pressure. Then, the residue obtained by distillation under reduced pressure was separated and purified through column chromatography to obtain 4.4 g of Intermediate 213-2 (yield: 93%). 
     C31H19Br: calc&#39;d: M+470.07 foun&#39;d: 470.08 
     (2) Synthesis of Intermediate 213-1 
     3 g of Intermediate 213-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.5 g of [1,1′-biphenyl]-4-amine was utilized instead of Intermediate (b), and 2.5 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a) (yield: 91%). 
     C24H17NO: calc&#39;d: M+335.13 foun&#39;d: 335.14 
     (3) Synthesis of Compound 213 
     5.1 g of Compound 213 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 4.4 g of Intermediate 213-2 was utilized instead of Intermediate (a), and 3 g of Intermediate 213-1 was utilized instead of Intermediate (b) (yield: 79%). 
     C55H35NO: calc&#39;d: M+725.27 foun&#39;d: 725.30 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.93 (dd, 2H), 7.79-7.78 (m, 2H), 7.72-7.59 (m, 6H), 7.54-7.28 (m, 15H), 7.20 (t, 2H), 6.89 (m, 2H), 6.75 (dd, 2H), 6.68 (dd, 1H), 6.56-6.54 (m, 2H), 5.68 (d, 1H) 
     Synthesis Example 20: Synthesis of Compound 219 
     
       
         
         
             
             
         
       
     
     3.1 g of Compound 219 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.4 g of Intermediate 213-2 was utilized instead of Intermediate (a), and 1.9 g of Intermediate 1-1 was utilized instead of Intermediate (b) (yield: 81%). 
     C58H39NO: calc&#39;d: M+765.30 foun&#39;d: 765.34 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.93 (dd, 2H), 7.79-7.67 (m, 6H), 7.62 (d, 1H), 7.53-7.28 (m, 11H), 7.18 (dt, 2H), 7.11 (dd, 2H), 6.89-6.82 (m, 3H), 6.75 (dd, 2H), 6.68 (dd, 1H), 6.50 (d, 1H). 6.10 (d, 1H), 1.61 (s, 6H) 
     Synthesis Example 21: Synthesis of Compound 240 
     
       
         
         
             
             
         
       
     
     2.5 g of Compound 240 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2 g of 6-bromo-2,9-diphenyl-9H-carbazole was utilized instead of Intermediate (a), and 1.7 g of Intermediate 213-1 was utilized instead of Intermediate (b) (yield: 78%). 
     C48H32N2O: calc&#39;d: M+625.25 foun&#39;d: 625.29 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.86 (dd, 1H), 7.79-7.76 (m, 2H), 7.73-7.70 (m, 3H), 7.65-7.61 (m, 2H), 7.55-7.28 (m, 18H), 7.24-7.21 (m, 2H), 6.70-6.65 (m, 3H), 6.59 (dd, 1H) 
     Synthesis Example 22: Synthesis of Compound 251 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 251-1 
     3.1 g of Intermediate 251-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.1 g of 9,9-dimethyl-9H-fluoren-1-amine was utilized instead of Intermediate (b), and 2.5 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a) (yield: 83%). 
     C27H21NO: calc&#39;d: M+375.16 foun&#39;d: 375.19 
     (2) Synthesis of Compound 251 
     4 g of Compound 251 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.1 g of Intermediate 251-1 was utilized instead of Intermediate (b), and 3.1 g of 3-iodo-9-phenyl-9H-carbazole was utilized instead of Intermediate (a) (yield: 78%). 
     C45H32N2O: calc&#39;d: M+616.25 foun&#39;d: 616.29 
       1 H NMR (500 MHz, CDCl 3 ) δ=8.22 (d, 1H), 7.82 (d, 1H), 7.77 (td, 1H), 7.70 (dd, 1H), 7.54-7.44 (m, 7H), 7.39-7.22 (m, 10H), 7.11 (dd, 1H), 6.96 (dd, 1H), 6.57-6.47 (m, 3H), 1.68 (s, 6H) 
     Synthesis Example 23: Synthesis of Compound 253 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 253-1 
     3.5 g of Intermediate 253-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.1 g of 9,9-dimethyl-9H-fluoren-4-amine was utilized instead of Intermediate (b), and 2.5 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a) (yield: 92%). 
     C27H21NO: calc&#39;d: M+375.16 foun&#39;d: 375.19 
     (2) Synthesis of Compound 253 
     4.6 g of Compound 253 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.5 g of Intermediate 253-1 was utilized instead of Intermediate (b), and 3.6 g of 3-iodo-9-phenyl-9H-carbazole was utilized instead of Intermediate (a) (yield: 81%). 
     C45H32N 2 O: calc&#39;d: M+616.25 foun&#39;d: 616.29 
       1 H NMR (500 MHz, CDCl 3 ) δ=8.22 (d, 1H), 7.82 (d, 1H), 7.72 (d, 1H), 7.63 (dd, 1H), 7.51-7.21 (m, 16H), 7.14-7.07 (m, 2H), 6.86 (dd, 1H), 6.61-6.59 (m, 1H), 6.53 (dd, 1H), 6.24 (td, 1H), 1.61 (s, 6H) 
     Synthesis Example 24: Synthesis of Compound 256 
     
       
         
         
             
             
         
       
     
     5.0 g of Compound 256 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.5 g of Intermediate 253-1 was utilized instead of Intermediate (b), and 3.2 g of 3-bromo-9-(4-fluorophenyl)-9H-carbazole was utilized instead of Intermediate (a) (yield: 84%). 
     C45H31FN2O: calc&#39;d: M+634.24 foun&#39;d: 634.25 
       1 H NMR (500 MHz, CDCl 3 ) δ=8.23 (d, 1H), 7.82 (d, 1H), 7.72 (td, 1H), 7.62 (dd, 1H), 7.58-7.35 (m, 3H), 7.34-7.21 (m, 10H), 7.14-7.03 (m, 4H), 6.86 (dd, 1H), 6.61 (m, 1H), 6.53 (dd, 1H), 6.24 (dd, 1H, 1.61 (s, 6H) 
     Synthesis Example 25: Synthesis of Compound 268 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 268-1 
     3.2 g of Intermediate 268-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 2.1 g of 9,9-dimethyl-9H-fluoren-2-amine was utilized instead of Intermediate (b), and 2.5 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a) (yield: 85%). 
     C27H21NO: calc&#39;d: M+375.16 foun&#39;d: 375.18 
     (2) Synthesis of Compound 268 
     5.7 g of Compound 268 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.2 g of Intermediate 268-1 was utilized instead of Intermediate (b), and 4.0 g of Intermediate 213-2 was utilized instead of Intermediate (a) (yield: 88%). 
     C58H39NO: calc&#39;d: M+765.30 foun&#39;d: 765.32 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.93 (dd, 2H), 7.79-7.66 (m, 6H). 7.62 (d, 1H), 7.53-7.29 (m, 11H), 7.20 (dt, 2H), 7.11-7.04 (m, 4H), 6.89 (d, 1H), 6.87 (t, 1H), 6.75 (t, 1H), 6.74 (d, 1H), 6.66 (dd, 1H), 6.42 (dd, 1H), 5.68 (d, 1H), 1.52 (s, 6H) 
     Synthesis Example 26: Synthesis of Compound 269 
     
       
         
         
             
             
         
       
     
     4.8 g of Compound 269 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.2 g of Intermediate 253-1 was utilized instead of Intermediate (b), and 4.0 g of Intermediate 213-2 was utilized instead of Intermediate (a) (yield: 74%). 
     C58H39NO: calc&#39;d: M+765.30 foun&#39;d: 765.32 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.93 (d, 2H), 7.82 (d, 1H), 7.80 (d, 1H), 7.72-7.58 (m, 5H), 7.53-7.36 (m, 7H), 7.33-7.05 (m, 9H), 6.87-6.84 (m, 2H), 6.79 (dd, 1H), 6.75 (dd, 2H), 6.61 (m, 1H), 6.23 (d, 1H), 5.49 (d, 1H), 1.61 (s, 6H) 
     Synthesis Example 27: Synthesis of Compound 278 
     
       
         
         
             
             
         
       
     
     4.3 g of Compound 278 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.2 g of Intermediate 253-1 was utilized instead of Intermediate (b), and 3.8 g of 2-bromo-9,9′-spirobi[fluorene] was utilized instead of Intermediate (a) (yield: 86%). 
     C52H35NO: calc&#39;d: M+689.27 foun&#39;d: 689.28 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.92 (d, 2H), 7.89 (d, 1H), 7.82 (d, 1H), 7.72 (d, 1H), 7.62 (dd, 1H), 7.59 (d, 1H), 7.48-7.41 (m, 4H), 7.32-7.06 (m, 10H), 6.87 (d, 1H), 6.81 (dd, 1H), 6.77-6.73 (m, 3H), 6.61 (m, 1H), 6.23 (d, 1H), 5.72 (dd, 1H), 1.61 (s, 6H) 
     Synthesis Example 28: Synthesis of Compound 281 
     
       
         
         
             
             
         
       
     
     (1) Synthesis of Intermediate 281-1 
     3.8 g of Intermediate 281-1 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.3 g of 9,9-diphenyl-9H-fluoren-4-amine was utilized instead of Intermediate (b), and 2.5 g of 1-bromodibenzo[b,d]furan was utilized instead of 5 g of Intermediate (a) (yield: 77%). 
     C37H25NO: calc&#39;d: M+499.19 foun&#39;d: 499.23 
     (2) Synthesis of Compound 281 
     4.9 g of Compound 281 was obtained in substantially the same manner as in Synthesis of Intermediate 1-1, except that 3.8 g of Intermediate 281-1 was utilized instead of Intermediate (b), and 3.2 g of 2-bromo-9,9′-spirobi[fluorene] was utilized instead of Intermediate (a) (yield: 79%). 
     C62H39NO: calc&#39;d: M+813.30 foun&#39;d: 813.33 
       1 H NMR (500 MHz, CDCl 3 ) δ=7.92 (d, 2H), 7.89 (d, 1H), 7.82 (d, 1H), 7.72 (d, 1H), 7.59 (dd, 2H), 7.49-7.40 (m, 4H), 7.33-7.26 (m, 4H), 7.21-7.05 (m, 14H), 6.81-6.71 (m, 6H), 6.62 (m, 1H), 6.56 (dd, 1H), 5.72 (d, 1H), 5.68 (t, 1H) 
     Compounds synthesized in Synthesis Examples 1 to 28 were identified by  1 H nuclear magnetic resonance (NMR). The results thereof are shown in Tables 1 and 2. Methods of synthesizing compounds other than compounds shown in Tables 1 and 2 may be easily understood to those skilled in the art by referring to the synthesis pathways and raw materials described above. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Compound 
                 1H NMR (400 Mhz) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1 
                 8.25(d, 1H), 7.85(d, 2H), 7.80-7.75(m, 2H), 
               
               
                   
                 7.73-7.70(m, 1H), 7.56(d, 1H), 7.53-7.21(m, 14H), 
               
               
                   
                 7.15-7.09(m, 2H), 7.00(dd, 3H), 6.85(dd, 1H), 
               
               
                   
                 6.65(dd, 1H), 6.55(dd, 1H), 1.61(s, 6H) 
               
               
                 2 
                 8.22-8.20(m, 1H), 7.86(td, 1H), 7.79-7.77(m, 1H), 
               
               
                   
                 7.72(m, 1H), 7.58(d, 1H), 7.51-7.23(m, 15H), 
               
               
                   
                 7.21-7.05(m, 11H), 6.81(td, 1H), 6.73(dd, 1H), 
               
               
                   
                 6.65(dd, 1H), 6.53-6.48(m, 2H) 
               
               
                 3 
                 8.22-8.20(m, 1H), 7.90(dd, 2H), 7.87(dd, 1H), 
               
               
                   
                 7.79(m, 1H), 7.72(m, 1H), 7.61(d, 1H), 
               
               
                   
                 7.54-7.12(m, 20H), 6.92(dd, 1H), 
               
               
                   
                 6.77-6.73(m, 3H), 6.66(dd, 1H), 6.51(dd, 1H), 
               
               
                   
                 5.97(q, 1H) 
               
               
                 5 
                 8.22-8.20(m, 1H), 7.85(m, 1H), 7.79-7.76(m, 2H), 
               
               
                   
                 7.71(m, 1H), 7.57(m, 1H), 7.46(dd, 1H), 
               
               
                   
                 7.40-7.21(m, 10H), 7.14-7.03(m, 4H), 7.01(dd, 1H), 
               
               
                   
                 6.85(dd, 1H), 6.66(dd, 1H), 6.54(dd, 1H), 
               
               
                   
                 1.61(s, 6H) 
               
               
                 6 
                 8.22-8.20(m, 1H), 7.86(td, 1H), 7.79-7.77(m, 1H), 
               
               
                   
                 7.72-7.70(m, 1H), 7.58(d, 1H). 7.48-7.23(m, 12H), 
               
               
                   
                 7.20-7.03(m, 13H), 6.81(dd, 1H), 6.73(dd, 1H), 
               
               
                   
                 6.66(dd, 1H), 6.53(q, 1H), 6.51(dd, 1H) 
               
               
                 21 
                 7.84-7.82(m, 1H), 7.79-7.75(m, 2H), 7.73-7.70(m, 2H), 
               
               
                   
                 7.68-7.65(m, 1H), 7.57-7.40(m, 5H), 7.34-7.25(m, 4H), 
               
               
                   
                 7.14-7.09(m, 2H), 7.03(dd, 1H), 6.85(m, 1H), 
               
               
                   
                 6.66(dd, 1H), 6.54(dd, 1H), 1.61(s, 6H) 
               
               
                 37 
                 8.22-8.20(m, 1H), 7.79(m, 1H), 7.72(m, 1H), 
               
               
                   
                 7.54-7.21(m, 14H), 7.08-7.02(m, 2H), 6.67-6.53(m, 3H), 
               
               
                   
                 6.34-6.31(m, 2H) 
               
               
                 93 
                 8.24-8.22(m, 1H), 8.15(m, 1H), 7.79-7.70(m, 4H), 
               
               
                   
                 7.67(d, 1H), 7.58-7.42(m, 8H), 7.39-7.25(m, 7H), 
               
               
                   
                 7.21-7.19(m, 1H), 7.14-7.09(m, 2H), 6.84(dd, 1H), 
               
               
                   
                 6.68(dd, 1H), 6.63-6.59(m, 2H), 6.49(m, 1H), 
               
               
                   
                 1.61(s, 6H) 
               
               
                 94 
                 8.24-8.22(m, 1H), 8.15(m, 1H), 7.86(td, 1H), 
               
               
                   
                 7.79-7.70(m, 3H), 7.67(d, 1H), 7.60-7.53(m, 3H), 
               
               
                   
                 7.50-7.25(m, 12H), 7.21-7.03(m, 12H), 6.81(td, 1H), 
               
               
                   
                 6.75(dd, 1H), 6.68(dd, 1H), 6.63-6.57(m, 3H), 
               
               
                   
                 6.44(d, 1H) 
               
               
                 95 
                 8.24-8.22(m, 1H), 8.15(m, 1H), 8.02-7.87(m, 3H), 
               
               
                   
                 7.79-7.70(m, 3H), 7.67(d, 1H), 7.60-7.53(m, 3H), 
               
               
                   
                 7.50-7.25(m, 14H), 7.23-7.15(m, 4H), 6.92(dd, 1H), 
               
               
                   
                 6.77-6.71(m, 3H), 6.68(dd, 1H), 6.63-6.57(m, 3H), 
               
               
                   
                 5.95(d, 1H) 
               
               
                 101 
                 8.24-8.22(m, 1H), 8.15(m, 1H), 7.79-7.70(m, 4H), 
               
               
                   
                 7.67(d, 1H), 7.58-7.52(m, 3H), 7.48-7.44(m, 1H), 
               
               
                   
                 7.39-7.25(m, 8H), 7.21-7.19(m, 1H), 
               
               
                   
                 7.14-7.03(m, 4H), 6.84(dd, 1H), 6.68(dd, 1H), 
               
               
                   
                 6.63-6.59(m, 2H), 6.49(m, 1H), 1.61(s, 6H) 
               
               
                 204 
                 7.92-7.87(m, 3H), 7.79(m, 1H), 7.72(m, 1H), 
               
               
                   
                 7.63-7.58(m, 3H), 7.52-7.24(m, 12H), 7.21-7.15(m, 3H), 
               
               
                   
                 6.92(dd, 1H), 6.77-6.71(m, 3H), 6.68-6.66(dd, 1H), 
               
               
                   
                 6.58-6.54(m, 2H), 5.95(dd, 1H) 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Compound 
                 1H NMR (500 Mhz) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 4 
                 8.22(m, 1H), 7.79(dd, 2H), 7.72(dd, 1H), 7.67(d, 1H), 
               
               
                   
                 7.54-7.14(m, 17H), 6.95(d, 1H), 6.90(dd, 1H), 
               
               
                   
                 6.66(dd, 1H),. 6.54(dd, 1H), 2.19-2.08(m, 2H), 
               
               
                   
                 1.95-1.72(m, 6H) 
               
               
                 8 
                 8.22(m, 1H), 7.79(dd, 2H), 7.72(dd, 1H), 7.67(d, 1H), 
               
               
                   
                 7.48-7.23(m, 13H), 7.18-7.14(m, 1H), 7.09-7.04(m, 2H), 
               
               
                   
                 6.95(d, 1H), 6.90(dd, 1H), 6.66(dd, 1H),. 6.54(dd, 1H), 
               
               
                   
                 2.19-2.08(m, 2H), 1.95-1.72(m, 6H) 
               
               
                 16 
                 8.22(m, 1H), 7.79(dd, 2H), 7.72(dd, 1H), 7.67(d, 1H), 
               
               
                   
                 7.63-7.59(m, 2H), 7.57-7.23(m, 18H), 7.18(dt, 1H), 
               
               
                   
                 6.95(d, 1H), 6.90(dd, 1H), 6.66(dd, 1H), 6.59(dd, 1H), 
               
               
                   
                 2.19-2.08(m, 2H), 1.95-1.72(m, 6H) 
               
               
                 187 
                 7.92-7.84(m, 4H), 7.79(m, 1H), 7.72(dd, 1H), 7.61(d, 1H), 
               
               
                   
                 7.58(d, 1H), 7.48-7.41(m, 5H), 7.36-7.28(m, 3H), 
               
               
                   
                 7.21-7.06(m, 14H), 6.92(dd, 1H), 6.81-6.72(m, 5H), 
               
               
                   
                 6.66(dd, 1H), 6.57(d, 1H), 6.43(d, 1H) 
               
               
                 188 
                 7.92(dd, 4H), 7.89(dd, 2H), 7.79(td, 1H), 7.72(dd, 1H), 
               
               
                   
                 7.61(d, 2H), 7.48-7.41(m, 7H), 7.36-7.26(m, 3H), 
               
               
                   
                 7.21-7.15(m, 6H), 6.92(dd, 2H), 6.77-6.73(m, 6H), 
               
               
                   
                 6.68(dd, 1H), 6.43(d, 2H) 
               
               
                 210 
                 7.92(dd, 2H), 7.89(dd, 1H), 7.80(d, 1H), 7.72(d, 1H), 
               
               
                   
                 7.59-7.51(m, 5H), 7.49-7.41(m, 5H), 7.32-7.27(m, 3H), 
               
               
                   
                 7.21-7.14(m, 5H), 7.01(t, 1H), 6.77-6.73(m, 4H), 
               
               
                   
                 6.66(dd, 1H), 6.61(dd, 1H), 5.47(d, 1H) 
               
               
                 213 
                 7.93(dd, 2H), 7.79-7.78(m, 2H), 7.72-7.59(m, 6H), 
               
               
                   
                 7.54-7.28(m, 15H), 7.20(t, 2H), 6.89(m, 2H), 
               
               
                   
                 6.75(dd, 2H), 6.68(dd, 1H), 6.56-6.54(m, 2H), 
               
               
                   
                 5.68(d, 1H) 
               
               
                 219 
                 7.93(dd, 2H), 7.79-7.67(m, 6H), 7.62(d, 1H), 
               
               
                   
                 7.53-7.28(m, 11H), 7.18(dt, 2H), 7.11(dd, 2H), 
               
               
                   
                 6.89-6.82(m, 3H), 6.75(dd, 2H), 6.68(dd, 1H), 
               
               
                   
                 6.50(d, 1H). 6.10(d, 1H), 1.61(s, 6H) 
               
               
                 240 
                 7.86(dd, 1H), 7.79-7.76(m, 2H), 7.73-7.70(m, 3H), 
               
               
                   
                 7.65-7.61(m, 2H), 7.55-7.28(m, 18H), 7.24-7.21(m, 2H), 
               
               
                   
                 6.70-6.65(m, 3H), 6.59(dd, 1H) 
               
               
                 251 
                 8.22(d, 1H), 7.82(d, 1 H), 7.77(td, 1H), 7.70(dd, 1H), 
               
               
                   
                 7.54-7.44(m, 7H), 7.39-7.22(m, 10H), 7.11(dd, 1H), 
               
               
                   
                 6.96(dd, 1H), 6.57-6.47(m, 3H), 1.68(s, 6H) 
               
               
                 253 
                 8.22(d, 1H), 7.82(d, 1 H), 7.72(d, 1H), 7.63(dd, 1 H), 
               
               
                   
                 7.51-7.21(m, 16H), 7.14-7.07(m, 2H), 6.86(dd, 1H), 
               
               
                   
                 6.61-6.59(m, 1H), 6.53(dd, 1H), 6.24(td, 1H), 1.61(s, 6H) 
               
               
                 256 
                 8.23(d, 1H), 7.82(d, 1H), 7.72(td, 1 H), 7.62(dd, 1H), 
               
               
                   
                 7.58-7.35(m, 3H), 7.34-7.21(m, 10H), 7.14-7.03(m, 4H), 
               
               
                   
                 6.86(dd, 1H), 6.61(m, 1H), 6.53(dd, 1 H), 6.24(dd, 1H, 
               
               
                   
                 1.61(s, 6H) 
               
               
                 268 
                 7.93(dd, 2H), 7.79-7.66(m, 6H). 7.62(d, 1H), 
               
               
                   
                 7.53-7.29(m, 11H), 7.20(dt, 2 H), 7.11-7.04(m, 4H), 
               
               
                   
                 6.89(d, 1 H), 6.87(t, 1H), 6.75(t, 1H), 
               
               
                   
                 6.74(d, 1H), 6.66(dd, 1H), 6.42(dd, 1 H), 5.68(d, 1 H), 
               
               
                   
                 1.52(s, 6H) 
               
               
                 269 
                 7.93(d, 2H), 7.82(d, 1H), 7.80(d, 1H), 7.72-7.58(m, 5H), 
               
               
                   
                 7.53-7.36(m, 7H), 7.33-7.05(m, 9H), 6.87-6.84(m, 2H), 
               
               
                   
                 6.79(dd, 1 H), 6.75(dd, 2 H), 6.61(m, 1H), 6.23(d, 1H), 
               
               
                   
                 5.49(d, 1H), 1.61(s, 6H) 
               
               
                 278 
                 7.92(d, 2H), 7.89(d, 1H), 7.82(d, 1 H), 7.72(d, 1H), 
               
               
                   
                 7.62(dd, 1H), 7.59(d, 1 H), 7.48-7.41(m, 4H), 
               
               
                   
                 7.32-7.06(m, 10H), 6.87(d, 1H), 6.81(dd, 1 H), 
               
               
                   
                 6.77-6.73(m, 3H), 6.61(m, 1 H), 6.23(d, 1H), 
               
               
                   
                 5.72(dd, 1H), 1.61(s, 6H) 
               
               
                 281 
                 7.92(d, 2H), 7.89(d, 1 H), 7.82(d, 1 H), 7.72(d, 1 H), 
               
               
                   
                 7.59(dd, 2H), 7.49-7.40(m, 4H), 7.33-7.26(m, 4H), 
               
               
                   
                 7.21-7.05(m, 14H), 6.81-6.71(m, 6H), 6.62(m, 1H), 
               
               
                   
                 6.56(dd, 1H), 5.72(d, 1H), 5.68(t, 1H) 
               
               
                   
               
            
           
         
       
     
     EXAMPLES 
     Comparative Example 1 
     A Corning 15 Ohms per square centimeter (0/cm 2 ) (1,200 Å) ITO glass substrate was cut to a size of 50 millimeters (mm)×50 mm×0.7 mm, sonicated in isopropyl alcohol and pure water for 5 minutes in each solvent, and cleaned by exposure to ultraviolet rays and ozone for 30 minutes to utilize the glass substrate as an anode. Then, the glass substrate was mounted to a vacuum-deposition apparatus. 
     2-TNATA was vacuum-deposited on the glass substrate to form a hole injection layer having a thickness of 600 Å. Thereafter, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (hereinafter referred to as “NPB”), which is a hole transport material, as a hole transporting compound was vacuum-deposited on the hole injection layer to form a hole transport layer having a thickness of 300 Å. 
     9,10-di(naphthalen-2-yl)anthracene (hereinafter referred to as “DNA”), which is a known blue fluorescent host, and 4,4′-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl (hereinafter referred to as “DPAVBi”), which is a known blue fluorescent dopant, were co-deposited on the hole transport layer in a weight ratio of about 98:2 to form an emission layer having a thickness of 300 Å. 
     
       
         
         
             
             
         
       
     
     Subsequently, Alq 3  was deposited on the emission layer to form an electron transport layer having a thickness of 300 Å. Subsequently, LiF, which is halogenated alkali metal, was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å. Finally, Al was vacuum-deposited on the electron injection layer to form a cathode having a thickness of 3,000 Å to form a LiF/Al electrode, thereby completing the manufacture of an organic light-emitting device. 
     Example 1 to 28 
     An organic light-emitting device was manufactured substantially in the same manner as in Comparative Example 1, except that Compounds shown in Table 3 were utilized instead of NPB in the formation of a hole transport layer. 
     Comparative Example 2 
     An organic light-emitting device was manufactured substantially in the same manner as in Comparative Example 1, except that Compound A was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 3 
     An organic light-emitting device was manufactured substantially in the same manner as in Comparative Example 1, except that Compound B was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 4 
     An organic light-emitting device was manufactured substantially in the same manner as in Comparative Example 1, except that Compound C was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 5 
     An organic light-emitting device was manufactured in substantially the same manner as in Comparative Example 1, except that Compound D was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 6 
     An organic light-emitting device was manufactured in substantially the same manner as in Comparative Example 1, except that Compound E was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 7 
     An organic light-emitting device was manufactured in substantially the same manner as in Comparative Example 1, except that Compound F was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 8 
     An organic light-emitting device was manufactured in substantially the same manner as in Comparative Example 1, except that Compound G was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     Comparative Example 9 
     An organic light-emitting device was manufactured in substantially the same manner as in Comparative Example 1, except that Compound H was utilized instead of NPB in the formation of a hole transport layer. 
     
       
         
         
             
             
         
       
     
     The performances (driving voltage, luminance, efficiency, and color-coordinate) of the organic light-emitting devices manufactured in Examples 1 to 28 and Comparative Examples 1 to 9 while driving at a current density of 50 mA/cm 2  were evaluated. The half lifespan was also measured at a current density of 100 mA/cm 2 , which indicates time (hour) for the luminance of each organic light-emitting device to decline to 50% of its initial luminance. The evaluation results are shown in Table 3. 
     The luminance was measured utilizing a luminance meter PR650 powered by a current voltmeter (Keithley SMU 236). 
     The efficiency was measured utilizing a luminance meter PR650 powered by a current voltmeter (Keithley SMU 236). 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                 Driving 
                 Current 
                   
                   
                   
                   
               
               
                   
                 Hole transport 
                 voltage 
                 density 
                 Luminance 
                 Efficiency 
                 Emission 
                 Half lifespan 
               
               
                   
                 material 
                 (V) 
                 (mA/cm 2 ) 
                 (cd/m 2 ) 
                 (cd/A) 
                 color 
                 (hr @ 100 mA/cm 2 ) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 Compound 1 
                 4.32 
                 50 
                 3670 
                 7.34 
                 Blue 
                 362 
               
               
                 Example 2 
                 Compound 2 
                 4.21 
                 50 
                 3715 
                 7.43 
                 Blue 
                 353 
               
               
                 Example 3 
                 Compound 3 
                 4.22 
                 50 
                 3665 
                 7.33 
                 Blue 
                 372 
               
               
                 Example 4 
                 Compound 4 
                 4.85 
                 50 
                 3876 
                 7.75 
                 Blue 
                 374 
               
               
                 Example 5 
                 Compound 5 
                 4.26 
                 50 
                 3730 
                 7.46 
                 Blue 
                 374 
               
               
                 Example 6 
                 Compound 6 
                 4.26 
                 50 
                 3730 
                 7.46 
                 Blue 
                 374 
               
               
                 Example 7 
                 Compound 8 
                 4.67 
                 50 
                 3985 
                 7.97 
                 Blue 
                 356 
               
               
                 Example 8 
                 Compound 16 
                 4.72 
                 50 
                 3451 
                 6.90 
                 Blue 
                 382 
               
               
                 Example 9 
                 Compound 21 
                 4.25 
                 50 
                 3630 
                 7.26 
                 Blue 
                 384 
               
               
                 Example 10 
                 Compound 37 
                 4.41 
                 50 
                 3725 
                 7.45 
                 Blue 
                 343 
               
               
                 Example 11 
                 Compound 93 
                 4.26 
                 50 
                 3630 
                 7.26 
                 Blue 
                 366 
               
               
                 Example 12 
                 Compound 94 
                 4.32 
                 50 
                 3670 
                 7.34 
                 Blue 
                 378 
               
               
                 Example 13 
                 Compound 95 
                 4.45 
                 50 
                 3440 
                 6.88 
                 Blue 
                 325 
               
               
                 Example 14 
                 Compound 101 
                 4.60 
                 50 
                 3490 
                 6.98 
                 Blue 
                 330 
               
               
                 Example 15 
                 Compound 187 
                 4.55 
                 50 
                 3655 
                 7.31 
                 Blue 
                 375 
               
               
                 Example 16 
                 Compound 188 
                 4.69 
                 50 
                 3492 
                 6.98 
                 Blue 
                 356 
               
               
                 Example 17 
                 Compound 204 
                 4.82 
                 50 
                 3540 
                 7.08 
                 Blue 
                 381 
               
               
                 Example 18 
                 Compound 210 
                 4.96 
                 50 
                 3987 
                 7.97 
                 Blue 
                 351 
               
               
                 Example 19 
                 Compound 213 
                 4.74 
                 50 
                 3859 
                 7.72 
                 Blue 
                 348 
               
               
                 Example 20 
                 Compound 219 
                 4.73 
                 50 
                 3565 
                 7.13 
                 Blue 
                 316 
               
               
                 Example 21 
                 Compound 240 
                 4.89 
                 50 
                 3529 
                 7.06 
                 Blue 
                 355 
               
               
                 Example 22 
                 Compound 251 
                 4.82 
                 50 
                 3983 
                 7.97 
                 Blue 
                 327 
               
               
                 Example 23 
                 Compound 253 
                 4.76 
                 50 
                 3852 
                 7.70 
                 Blue 
                 331 
               
               
                 Example 24 
                 Compound 256 
                 4.96 
                 50 
                 3874 
                 7.75 
                 Blue 
                 326 
               
               
                 Example 25 
                 Compound 268 
                 4.81 
                 50 
                 3721 
                 7.44 
                 Blue 
                 312 
               
               
                 Example 26 
                 Compound 269 
                 4.53 
                 50 
                 3652 
                 7.30 
                 Blue 
                 332 
               
               
                 Example 27 
                 Compound 278 
                 4.56 
                 50 
                 3552 
                 7.10 
                 Blue 
                 351 
               
               
                 Example 28 
                 Compound 281 
                 4.66 
                 50 
                 3512 
                 7.02 
                 Blue 
                 366 
               
               
                 Comparative 
                 NPB 
                 7.01 
                 50 
                 2645 
                 5.29 
                 Blue 
                 258 
               
               
                 Example 1 
               
               
                 Comparative 
                 Compound A 
                 6.50 
                 50 
                 2805 
                 5.61 
                 Blue 
                 220 
               
               
                 Example 2 
               
               
                 Comparative 
                 Compound B 
                 5.81 
                 50 
                 3105 
                 6.21 
                 Blue 
                 180 
               
               
                 Example 3 
               
               
                 Comparative 
                 Compound C 
                 6.02 
                 50 
                 3205 
                 6.41 
                 Blue 
                 210 
               
               
                 Example 4 
               
               
                 Comparative 
                 Compound D 
                 8.21 
                 50 
                 1851 
                 3.70 
                 Blue 
                 127 
               
               
                 Example 5 
               
               
                 Comparative 
                 Compound E 
                 6.01 
                 50 
                 2353 
                 5.98 
                 Blue 
                 231 
               
               
                 Example 6 
               
               
                 Comparative 
                 Compound F 
                 7.32 
                 50 
                 2553 
                 5.90 
                 Blue 
                 221 
               
               
                 Example 7 
               
               
                 Comparative 
                 Compound G 
                 5.88 
                 50 
                 2678 
                 5.34 
                 Blue 
                 231 
               
               
                 Example 8 
               
               
                 Comparative 
                 Compound H 
                 5.68 
                 50 
                 2635 
                 5.27 
                 Blue 
                 235 
               
               
                 Example 9 
               
               
                   
               
            
           
         
       
     
     As apparent from Table 3, when the compound according to one or more embodiments is utilized as a hole transport material in organic light-emitting devices, the organic light-emitting devices of the Examples including the compound according to one or more embodiments were found to have improved driving voltage, excellent I-V-L characteristics with improved efficiency, and particularly, significant improvement of lifespan due to its lifespan improving effects, as compared with the organic light-emitting device of the Comparative Example 1 including NPB. In addition, even in comparison with Comparative Examples 2 to 9, in which Compounds A, B, C, D, E, F, G, and H were respectively utilized, the organic light-emitting device of the Examples were found to have improved driving voltage, improved luminance, improved luminescence efficiency, and improved half lifespan. 
     As apparent from the foregoing description, an organic light-emitting device including the amine-based compound may have a low driving voltage, high efficiency, long lifespan, and high maximum quantum efficiency. 
     It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. 
     While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims, and equivalents thereof.