Patent Publication Number: US-9899611-B2

Title: Condensed cyclic compound and organic light-emitting device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2014-0119380, filed on Sep. 5, 2014, in the Korean Intellectual Property Office, and entitled: “Condensed Cyclic Compound and Organic Light-Emitting Device Including the Same,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a condensed cyclic compound and an organic light-emitting device including the same. 
     2. Description of the Related Art 
     Organic light emitting devices are self-emission devices that may have wide viewing angles, high contrast ratios, short response times, and excellent brightness, driving voltage, and response speed characteristics, and produce full-color images. 
     The organic light-emitting device may include a first electrode disposed on a substrate, and a hole transport region, an emission layer, an electron transport region, and a second electrode, which are sequentially disposed on the first electrode. Holes provided from the first electrode may move toward the emission layer through the hole transport region, and electrons provided from the second electrode may move toward the emission layer through the electron transport region. Carriers, such as holes and electrons, may be recombined in the emission layer to produce excitons. These excitons may change from an excited state to a ground state, thereby generating light. 
     SUMMARY 
     The embodiments may provide a condensed cyclic 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. 
     An aspect of embodiments provides a condensed cyclic compound represented by Formula 1 below: 
     
       
         
         
             
             
         
       
     
     wherein in the Formula 1 above, 
     L 1  is 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; 
     a1 is selected from 0, 1, 2, and 3, and when a1 is two or more, a plurality of L 1  are identical or different; 
     A 1  is selected from a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), —S(═O) 2 (R 27 ), 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  arylthiogroup, 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 1 )(Q 2 )(Q 3 ), —B(Q 4 )(Q 5 ), and —N(Q 6 )(Q 7 ); 
     b1 is an integer selected from 1, 2, 3, and 4, and when b1 is 2 or more, a plurality of A 1  are identical or different. 
     R 1  to R 11  are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 31 )(R 32 ), —P(═S)(R 33 )(R 34 ), —S(═O)(R 35 )(R 36 ), —S(═O) 2 (R 37 ), 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  arylthiogroup, 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 11 )(Q 12 )(Q 13 ), —B(Q 14 )(Q 15 ), and —N(Q 16 )(Q 17 ); 
     R 21  to R 27  and R 31  to R 37  are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone 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 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; 
     at least one substituent of the substituted C 3 -C 10  cycloalkylene group, substituted C 1 -C 10  heterocycloalkylene group, substituted C 3 -C 10  cycloalkenylene group, substituted C 1 -C 10  heterocycloalkenylene group, substituted C 6 -C 60  arylene group, substituted C 1 -C 60  heteroarylene group, substituted divalent non-aromatic condensed polycyclic group, substituted divalent non-aromatic condensed heteropolycyclic group, substituted C 1 -C 60  alkyl group, substituted C 2 -C 60  alkenyl group, substituted C 2 -C 60  alkynyl group, substituted C 1 -C 60  alkoxy group, substituted C 3 -C 10  cycloalkyl group, substituted C 1 -C 10  heterocycloalkyl group, substituted C 3 -C 10  cycloalkenyl group, substituted C 1 -C 10  heterocycloalkenyl group, substituted C 6 -C 60  aryl group, substituted C 6 -C 60  aryloxy group, substituted C 6 -C 60  arylthio group, substituted C 1 -C 60  heteroaryl group, substituted monovalent non-aromatic condensed polycyclic group, and substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from 
     a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, 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; 
     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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, 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 ), —B(Q 24 )(Q 25 ), and —N(Q 26 )(Q 27 ); and 
     —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 34 )(Q 35 ), and —N(Q 36 )(Q 37 ); 
     wherein Q 1  to Q 7 , Q 11  to Q 17 , Q 21  to Q 27 , and Q 31  to Q 37  may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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, and a monovalent non-aromatic condensed heteropolycyclic group. 
     Another aspect of embodiments provides an organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer that is disposed between the first electrode and the second electrode and includes an emission layer, wherein the organic layer includes at least one of the condensed cyclic compound described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Features will be apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawing in which: 
         FIG. 1  illustrates a schematic view of an organic light-emitting device according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawing; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art. 
     In the drawing FIGURE, the dimensions of layers and regions may be exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout. 
     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. 
     A condensed cyclic compound according to an embodiment may be represented by Formula 1 below. 
     
       
         
         
             
             
         
       
     
     L 1  in Formula 1 may be selected from or include, e.g., 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/or a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group. 
     In an implementation, L 1  in Formula 1 may 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-fluorenylene 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 pyrrolylene group, a thiophenylene group, a furanylene group, an imidazolylene group, a pyrazolylene group, a thiazolylene group, an isothiazolylene group, an oxazolylene group, a isoxazolylene group, a pyridinylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, an isoindolylene group, an indolylene group, an indazolylene group, a purinylene 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 carbazolylene group, a phenanthridinylene group, an acridinylene group, a phenanthrolinylene group, a phenazinylene group, a benzoimidazolylene group, a benzofuranylene group, a benzothiophenylene group, an isobenzothiazolylene group, a benzoxazolylene group, an isobenzoxazolylene group, a triazolylene group, a tetrazolylene group, an oxadiazolylene group, a triazinylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a thiadiazolylene group, an imidazopyridinylene group, and an imidazopyrimidinylene 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-fluorenylene 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 pyrrolylene group, a thiophenylene group, a furanylene group, an imidazolylene group, a pyrazolylene group, a thiazolylene group, an isothiazolylene group, an oxazolylene group, a isoxazolylene group, a pyridinylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, an isoindolylene group, an indolylene group, an indazolylene group, a purinylene 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 carbazolylene group, a phenanthridinylene group, an acridinylene group, a phenanthrolinylene group, a phenazinylene group, a benzoimidazolylene group, a benzofuranylene group, a benzothiophenylene group, an isobenzothiazolylene group, a benzoxazolylene group, an isobenzoxazolylene group, a triazolylene group, a tetrazolylene group, an oxadiazolylene group, a triazinylene group, a dibenzofuranylene group, a dibenzothiophenylene group, a benzocarbazolylene group, a dibenzocarbazolylene group, a thiadiazolylene group, an imidazopyridinylene group, and an imidazopyrimidinylene group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group. 
     In an implementation, L 1  in Formula 1 may be a group represented by one of Formulae 3-1 to 3-32 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In Formulae 3-1 to 3-32, 
     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 or include a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and/or a triazinyl group; 
     d1 may be an integer selected from 1, 2, 3, and 4, d2 may be an integer selected from 1, 2, and 3, d3 may be an integer selected from 1, 2, 3, 4, 5, and 6, d4 may be an integer selected from 1, 2, 3, 4, 5, 6, 7, and 8, d5 may be 1 or 2, and d6 may be an integer selected from 1, 2, 3, 4, and 5, and * and *′ indicate or represent binding sites to a neighboring atom. 
     In an implementation, L 1  in Formula 1 may be a group represented by one of Formulae 4-1 to 4-32 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     * and *′ in Formulae 4-1 to 4-32 indicate or represent a binding site to a neighboring atom, and CN is a cyano group. 
     a1 in Formula 1 indicates the number of L 1  and may be an integer selected from 0, 1, 2 and 3. In an implementation, a1 may be, e.g., 0 or 1. When a1 is 0, *-(L 1 ) a1 -*′ may be a single bond. When a1 is 2 or more, a plurality of L 1  may be identical or different. 
     In an implementation, a1 in Formula 1 may be 0, 1, or 2. 
     A 1  in Formula 1 may be selected from or include, e.g., a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), —S(═O) 2 (R 27 ), 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-C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C-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  arylthiogroup, a substituted or unsubstituted C-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 1 )(Q 2 )(Q 3 ), —B(Q 4 )(Q 5 ), and/or —N(Q 6 )(Q 7 ). 
     In an implementation, A 1  in Formula 1 may be selected from: 
     a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), and —S(═O) 2 (R 27 ); 
     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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and a benzophenanthridinyl group; 
     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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and a benzophenanthridinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and —Si(Q 31 )(Q 32 )(Q 33 ); and 
     —Si(Q 1 )(Q 2 )(Q 3 ), 
     Q 1  to Q 3  and Q 31  to Q 33  may each independently be selected from or include, e.g., a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and/or a triazinyl group. 
     In an implementation, A 1  in Formula 1 may be selected from: 
     a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), and —S(═O) 2 (R 27 ); 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, and a benzophenanthridinyl group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, and a benzophenanthridinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group and —Si(Q 31 )(Q 32 )(Q 33 ); and 
     —Si(Q 1 )(Q 2 )(Q 3 ), 
     Q 1  to Q 3  and Q 31  to Q 33  may each independently be selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group. 
     In an implementation, A 1  in Formula 1 may be selected from: 
     a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), and —S(═O) 2 (R 27 ); and 
     a group represented by one of Formulae 5-1 to 5-16 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In Formulae 5-1 to 5-16, 
     Y 31  may be O, S, C(Z 34 )(Z 35 ) or N(Z 36 ); 
     Z 31  to Z 36  may each independently be selected from or include: 
     a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), —S(═O) 2 (R 27 ), a C 1 -C 20  alkyl group, and a C 1 -C 20  alkoxy group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group and a naphthyl group; and/or 
     —Si(Q 31 )(Q 32 )(Q 33 ). 
     Q 31  to Q 33  may each independently be selected from or include a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and/or a triazinyl group. 
     e1 may be an integer selected from 1, 2, 3, 4, and 5; e2 may be an integer selected from 1, 2, 3, 4, 5, 6, and 7; e3 may be an integer selected from 1, 2, and 3; e4 may be an integer selected from 1, 2, 3, and 4; e5 may be an integer selected from 1 and 2; and * indicates a binding site to a neighboring atom. 
     In an implementation, A 1  in Formula 1 may be selected from, e.g., a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), and —S(═O) 2 (R 27 ); and 
     a group represented by one of Formulae 6-1 to 6-65 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     * in Formulae 6-1 to 6-65 indicates a binding site to a neighboring atom, CN is a cyano group, and Ph is a phenyl group. 
     b1 in Formula 1 indicates the number of A 1  and may be an integer selected from 1, 2, 3, and 4. When b1 is 2 or more, a plurality of A 1  may be identical or different. 
     R 1  to R 11  in Formula 1 may each independently be selected from or include, e.g., a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 31 )(R 32 ), —P(═S)(R 33 )(R 34 ), —S(═O)(R 35 )(R 36 ), —S(═O) 2 (R 37 ), 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  arylthiogroup, 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 11 )(Q 12 )(Q 13 ), —B(Q 14 )(Q 15 ), and/or —N(Q 16 )(Q 17 ). 
     In an implementation, R 1  to R 11  in Formula 1 may each independently be selected from or include a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 31 )(R 32 ), —P(═S)(R 33 )(R 34 ), —S(═O)(R 35 )(R 36 ), —S(═O) 2 (R 37 ), 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 6 -C 20  aryl group, a substituted or unsubstituted C 1 -C 20  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and/or —Si(Q 11 )(Q 12 )(Q 13 ). 
     In an implementation, R 1  to R 11  in Formula 1 may each independently be selected from or include, e.g., a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 31 )(R 32 ), —P(═S)(R 33 )(R 34 ), —S(═O)(R 35 )(R 36 ), —S(═O) 2 (R 37 ), a substituted or unsubstituted C 1 -C 20  alkyl group, and/or a substituted or unsubstituted C 1 -C 20  alkoxy group. 
     R 21  to R 27  and R 31  to R 37  in Formula 1 may each independently be selected from or include, e.g., a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone 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 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and/or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. 
     In an implementation, R 21  to R 27 , and R 31  to R 37  in Formula 1 may each independently be selected from or include, e.g., a substituted or unsubstituted C 6 -C 20  aryl group, a substituted or unsubstituted C 1 -C 20  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and/or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. 
     In an implementation, R 21  to R 27  and R 31  to R 37  in Formula 1 may each independently be selected from or include: 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and/or a dibenzocarbazolyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, and —Si(Q 31 )(Q 32 )(Q 33 ). 
     In an implementation, R 21  to R 27  and R 31  to R 37  in Formula 1 may each independently be selected from or include a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group and a naphthyl group. 
     In an implementation, R 21  to R 27  may each independently be selected from or include a phenyl group, a naphthyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, and a naphthyl group. 
     In an implementation, the compound represented by Formula 1 may be, e.g., represented by Formula 1A below. 
     
       
         
         
             
             
         
       
     
     L 1 , a1, A 1 , and b 1  in Formula 1A may be the same as described above with respect to Formula 1. 
     For example, in Formula 1A, L 1  may be selected from a group represented by one of Formulae 4-1 to 4-32, and a1 may be selected from 0, 1, and 2. 
     In an implementation, A 1  in Formula 1 may be selected from or include, e.g., a deuterium, —F, —Cl, —Br, —I, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, —P(═O)(R 21 )(R 22 ), —P(═S)(R 23 )(R 24 ), —S(═O)(R 25 )(R 26 ), and —S(═O) 2 (R 27 ); and 
     a group represented by one of Formulae 6-1 to 6-65 as described above. 
     R 21  to R 27  may each independently be selected from or include a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, and a naphthyl group. 
     In an implementation, the condensed cyclic compound represented by Formula 1 may be one of Compounds 1 to 100 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The condensed cyclic compound represented by Formula 1 may have a core moiety represented by Formula 1′ below. For example, the condensed cyclic compound may have electrochemical stability, and accordingly, an organic light-emitting device using the condensed cyclic compound represented by Formula 1 may have high efficiency. 
     
       
         
         
             
             
         
       
     
     In the condensed cyclic compound represented by Formula 1, b1 may be an integer selected from 1, 2, 3, and 4, and A 1  may not be a hydrogen. For example the core moiety represented by Formula 1′ may necessarily be substituted with -[(L 1 ) a1 -(A 1 ) b1 ], and not a hydrogen, the condensed cyclic compound may have an energy level that is appropriate for use as a material for an organic light-emitting device, e.g., an electron transport material. Accordingly, an organic light-emitting device using the condensed cyclic compound represented by Formula 1 may have high efficiency. 
     The condensed cyclic compound represented by Formula 1 may be synthesized by using a suitable organic synthetic method. A synthesis method of the condensed cyclic compound may be understood in view of the following embodiments. 
     The condensed cyclic compound of Formula 1 may be used or included between a pair of electrodes of an organic light-emitting device. In an implementation, the condensed cyclic compound may be included an electron transport region, e.g., an electron transport layer. For example, an organic light-emitting device according to an embodiment may include: a first electrode; a second electrode facing the first electrode; and an organic layer that is disposed between the first electrode and the second electrode and includes an emission layer, wherein the organic layer includes at least one of the condensed cyclic compounds described above. 
     The expression that “(an organic layer) includes at least one condensed cyclic compound” used herein may include a case in which “(an organic layer) includes identical compounds represented by Formula 1 and a case in which (an organic layer) includes two or more different condensed cyclic compounds represented by Formula 1. 
     For example, the organic layer may include, as the condensed cyclic compound, only Compound 1. In this regard, Compound 1 may exist in an electron transport layer of the organic light-emitting device. In another embodiment, the organic layer may include, as the condensed cyclic compound, Compound 1 and Compound 2. In this regard, Compound 1 and Compound 2 may exist in an identical layer (for example, Compound 1 and Compound 2 may all exist in an electron transport layer), or different layers (for example, Compound 1 may exist in an emission layer and Compound 2 may exist in an electron transport layer). 
     The organic layer may include, e.g., i) a hole transport region that is between the first electrode (anode) and the emission layer and that includes at least one of a hole injection layer, a hole transport layer, a buffer layer, and an electron blocking layer, and ii) an electron transport region that is between the emission layer and the second electrode (cathode) and that includes at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer. The electron transport region may include at least one condensed cyclic compound represented by Formula 1. For example, the electron transport region may include the electron transport layer, and the electron transport layer may include at least one condensed cyclic compound represented by Formula 1. 
     The term “organic layer” used herein refers to a single layer and/or a plurality of layers disposed between the first electrode and the second electrode of an organic light-emitting device. A material included in the “organic layer” is not limited to an organic material. 
       FIG. 1  illustrates a schematic 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 an organic light-emitting device according to an embodiment and a method of manufacturing an organic light-emitting device according to an embodiment will be described in connection with  FIG. 1 . 
     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 transparent plastic substrate, each with excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water repellency. 
     The first electrode  110  may be formed by depositing or sputtering a material for forming the first electrode on the substrate. When the first electrode  110  is an anode, the material for the first electrode may be selected from materials with a high work function to facilitate hole injection. The first electrode  110  may be a reflective electrode or a transmissive electrode. The material for the first electrode may be a transparent and highly conductive material, and examples of such a material are indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO 2 ), and zinc oxide (ZnO). When the first electrode  110  is a semi-transmissive electrode or a reflective electrode, as a material for forming the first electrode, at least one of magnesium (Mg), aluminum(Al), aluminum-lithium(Al—Li), calcium (Ca), magnesium-indium(Mg—In), magnesium-silver (Mg—Ag) may be used. 
     The first electrode  110  may have a single-layer structure, or a multi-layer structure including two or more layers. For example, the first electrode  110  may have a three-layered structure of ITO/Ag/ITO, but the structure of the first electrode  110  is not limited thereto. 
     The organic layer  150  may be disposed 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 and the emission layer, and an electron transport region between the emission layer and the second electrode. 
     The hole transport region may include at least one selected from a hole injection layer (HIL), a hole transport layer (HTL), a buffer layer, and an electron blocking layer (EBL), and the electron transport region may include at least one selected from a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL), but they are not limited thereto. 
     The hole transport region may have a single-layered structure formed of a single material, a single-layered structure formed of a plurality of different materials, or a multi-layered structure having a plurality of layers formed of a plurality of different materials. 
     For example, the hole transport region may have a single-layered structure formed of a plurality of different materials, or a structure of hole injection layer/hole transport layer, a structure of hole injection layer/hole transport layer/buffer layer, a structure of hole injection layer/buffer layer, a structure of hole transport layer/buffer layer, or a structure of hole injection layer/hole transport layer/electron blocking layer, wherein layers of each structure are sequentially stacked from the first electrode  110  in this stated order. 
     When the hole transport region includes a hole injection layer, the hole injection layer may be formed on the first electrode  110  by using various methods, e.g., vacuum deposition, spin coating casting, a Langmuir-Blodgett (LB) method, ink-jet printing, laser-printing, or laser-induced thermal imaging. 
     When a hole injection layer is formed by vacuum deposition, e.g., the vacuum deposition may be performed at a temperature of a deposition temperature of about 100 to about 500° C., at a vacuum degree of about 10 −8  to about 10 −3  torr, and/or at a deposition rate of about 0.01 to about 100 Å/sec, in consideration of a compound for a hole injection layer to be deposited, and the structure of a hole injection layer to be formed. 
     When a hole injection layer is formed by spin coating, the spin coating may be performed at a coating rate of about 2,000 rpm to about 5,000 rpm, and at a temperature of about 80° C. to 200° C., in consideration of a compound for a hole injection layer to be deposited, and the structure of a hole injection layer to be formed. 
     When the hole transport region includes a hole transport layer, the hole transport layer may be formed on the first electrode  110  or the hole injection layer by using various methods, e.g., vacuum deposition, spin coating, casting, a LB method, ink-jet printing, laser-printing, or laser-induced thermal imaging. When the hole transport layer is formed by vacuum deposition or spin coating, deposition and coating conditions for the hole transport layer may be determined by referring to the deposition and coating conditions for the hole injection layer. 
     The hole transport region may include at least one selected from m-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, Spiro-TPD, Spiro-NPB, α-NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/camphor sulfonicacid (PANI/CSA), (polyaniline)/poly(4-styrenesulfonate) (Pani/PSS), a compound represented by Formula 201 below, and a compound represented by Formula 202 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In Formulae 201 and 202, 
     L 201  to L 205  may be the same as explained in connection with L 1 ; 
     xa1 to xa4 may be each independently selected from 0, 1, 2, and 3; 
     xa5 may be selected from 1, 2, 3, 4, and 5; and 
     R 201  to R 204  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, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. 
     In an implementation, in Formulae 201 and 202, 
     L 201  to L 205  may be each independently selected from: 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorene group, a dibenzofluorene group, a phenanthrenylene group, an anthracenylene group, a pyrenylene group, a chrysenylene group, a pyridinylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a quinolinylene group, an isoquinolinylene group, a quinoxalinylene group, a quinazolinylene group, a carbazolylene group, and a triazinylene group; and 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorene group, a dibenzofluorene group, a phenanthrenylene group, an anthracenylene group, a pyrenylene group, a chrysenylene group, a pyridinylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a quinolinylene group, an isoquinolinylene group, a quinoxalinylene group, a quinazolinylene group, a carbazolylene group, and a triazinylene group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     xa1 to xa4 may be each independently 0, 1, or 2; 
     xa5 may be 1, 2, or 3; 
     R 201  to R 204  may be each independently selected from: 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, an azulenyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group. 
     The compound represented by Formula 201 may be represented by Formula 201A: 
     
       
         
         
             
             
         
       
     
     In an implementation, the compound represented by Formula 201 may be represented by Formula 201A-1 below. 
     
       
         
         
             
             
         
       
     
     In an implementation, the compound represented by Formula 202 may be represented by Formula 202A below. 
     
       
         
         
             
             
         
       
     
     L 201  to L 203 , xa1 to xa3, xa5, and R 202  to R 204  in Formulae 201A, 201A-1, and 202A are already described above, R 211  may be the same as defined in connection with R 203 , and R 213  to R 216  may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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, and a monovalent non-aromatic condensed heteropolycyclic group. 
     For example, in Formulae 201A, 201A-1, and 202A, 
     L 201  to L 203  may each independently be selected from: 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a pyrenylene group, a chrysenylene group, a pyridinylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a quinolinylene group, an isoquinolinylene group, a quinoxalinylene group, a quinazolinylene group, a carbazolylene group, and a triazinylene group; and 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a pyrenylene group, a chrysenylene group, a pyridinylene group, a pyrazinylene group, a pyrimidinylene group, a pyridazinylene group, a quinolinylene group, an isoquinolinylene group, a quinoxalinylene group, a quinazolinylene group, a carbazolylene group, and a triazinylene group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     xa1 to xa3 may be each independently 0 or 1; 
     R 203 , R 211 , and R 212  may each independently be selected from: 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     R 213  and R 214  may each independently be selected from: 
     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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     R 215  and R 216  may each independently be selected from: 
     a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     xa5 may be 1 or 2. 
     In an implementation, R 213  and R 214  in Formulae 201A, and 201A-1 may bind to each other to form a saturated or unsaturated ring. 
     In an implementation, the compound represented by Formula 201, and the compound represented by Formula 202 may each include compounds HT1 to HT20 illustrated below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     A thickness of the hole transport region may be in a range of about 100 Å to about 10,000 Å, e.g., about 100 Å to about 1,000 Å. When the hole transport region includes a hole injection layer and a hole transport layer, the thickness of the hole injection layer may be in a range of about 100 Å to about 10,000 Å, e.g., about 100 Å to about 1,000 Å, and the thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, e.g., 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 these ranges, satisfactory hole transporting characteristics may be obtained without a substantial increase in driving voltage. 
     The hole transport region may further include, in addition to these materials, a charge-generation material for the improvement of conductive properties. The charge-generation material may be homogeneously or non-homogeneously dispersed in the hole transport region. 
     The charge-generation material may be, e.g., a p-dopant. The p-dopant may include one of a quinone derivative, a metal oxide, and a cyano group-containing compound, but is not limited thereto. Examples of the p-dopant may include a quinone derivative, such as tetracyanoquinonedimethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ); a metal oxide, such as a tungsten oxide or a molybdenum oxide, and Compound HT-D1 illustrated below. 
     
       
         
         
             
             
         
       
     
     The hole transport region may further include, in addition to the hole injection layer and the hole transport layer, at least one of a buffer layer and an electron blocking layer. Since the buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, light-emission efficiency of a formed organic light-emitting device may be improved. For use as a material included in the buffer layer, materials that are included in the hole transport region may be used. The electron blocking layer prevents injection of electrons from the electron transport region. 
     An emission layer may be formed on the first electrode  110  or the hole transport region by using various methods, e.g., vacuum deposition, spin coating, casting, a LB method, ink jet printing, laser-printing, or laser-induced thermal imaging. When the emission layer is formed by vacuum deposition or spin coating, deposition and coating conditions for the emission layer may be determined by referring to the deposition and coating conditions for the hole injection layer. 
     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 an implementation, the emission layer may have a stacked structure of a red emission layer, a green emission layer, and a blue emission layer, or may include a red-light emission material, a green-light emission material, and a blue-light emission material, which are mixed with each other in a single layer, to emit white light. 
     The emission layer may include a host and a dopant. 
     The host may include at least one selected from TPBi, TBADN, ADN (also referred to as “DNA”), CBP, CDBP, and TCP: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In an implementation, the host may include a compound represented by Formula 301 below.
 
Ar 301 -[(L 301 ) xe1 -E 301 ] xe2   &lt;Formula 301&gt;
 
     In Formula 301, 
     Ar 301  may be selected from: 
     a naphthalene group, a heptalene group, a fluorenene group, a spiro-fluorenene group, a benzofluorenene group, a dibenzofluorenene 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, and an indenoanthracene group; 
     a naphthalene group, a heptalene group, a fluorenene group, a spiro-fluorenene group, a benzofluorenene group, a dibenzofluorenene group, a phenalene group, a phenanthrene group, a 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, and an indenoanthracene group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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, 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, 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, and —Si(Q 301 )(Q 302 )(Q 303 ) (wherein Q 301  to Q 303  are each independently selected from a hydrogen, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  aryl group, and a C 1 -C 60  heteroaryl group); 
     L 301  may be the same as explained in connection with L 201 ; 
     R 301  may be selected from: 
     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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group; 
     xb1 may be selected from 0, 1, 2, and 3; 
     xb2 may be selected from 1, 2, 3, and 4. 
     wherein in Formula 301, 
     L 301  may be selected from: 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a pyrenylene group, and a chrysenylene group; and 
     a phenylene group, a naphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenanthrenylene group, an anthracenylene group, a pyrenylene group, and a chrysenylene group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, and a chrysenyl group; 
     R 301  may be selected from: 
     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 of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, and a chrysenyl group; 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, and a chrysenyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, and a chrysenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, and a chrysenyl group, but is not limited thereto. 
     In an implementation, the host may include a compound represented by Formula 301A below. 
     
       
         
         
             
             
         
       
     
     Substituents of Formula 301A may be understood by corresponding descriptions provided herein. 
     The compound represented by Formula 301 may include at least one of Compounds H1 to H42. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In an implementation, the host may include at least one of Compounds H43 to H49 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The dopant may be at least one selected from a fluorescent dopant and a phosphorescent dopant. 
     In an implementation, the phosphorescent dopant may include an organometallic complex represented by Formula 401 below. 
     
       
         
         
             
             
         
       
     
     In Formula 401, 
     M may be selected from iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), and thulium (Tm); 
     X 401  to X 404  may each independently be nitrogen or carbon; 
     rings A 401  and A 402  may each independently be selected from a substituted or unsubstituted benzene, a substituted or unsubstituted naphthalene, a substituted or unsubstituted fluorenene, a substituted or unsubstituted spiro-fluorenene, a substituted or unsubstituted indene, a substituted or unsubstituted pyrrol, a substituted or unsubstituted thiophene, a substituted or unsubstituted furan, a substituted or unsubstituted imidazole, a substituted or unsubstituted pyrazole, a substituted or unsubstituted thiazole, a substituted or unsubstituted isothiazole, a substituted or unsubstituted oxazole, a substituted or unsubstituted isoxazole, a substituted or unsubstituted pyridine, a substituted or unsubstituted pyrazine, a substituted or unsubstituted pyrimidine, a substituted or unsubstituted pyridazine, a substituted or unsubstituted quinoline, a substituted or unsubstituted isoquinoline, a substituted or unsubstituted benzoquinoline, a substituted or unsubstituted quinoxaline, a substituted or unsubstituted quinazoline, a substituted or unsubstituted carbazol, a substituted or unsubstituted benzoimidazole, a substituted or unsubstituted benzofuran, a substituted or unsubstituted benzothiophene, a substituted or unsubstituted isobenzothiophene, a substituted or unsubstituted benzooxazole, a substituted or unsubstituted isobenzooxazole, a substituted or unsubstituted triazole, a substituted or unsubstituted oxadiazole, a substituted or unsubstituted triazine, a substituted or unsubstituted dibenzofuran, and a substituted or unsubstituted dibenzothiophene; and 
     at least one substituent of the substituted benzene, substituted naphthalene, substituted fluorenene, substituted spiro-fluorenene, substituted indene, substituted pyrrol, substituted thiophene, substituted furan, substituted imidazole, substituted pyrazole, substituted thiazole, substituted isothiazole, substituted oxazole, substituted isoxazole, substituted pyridine, substituted pyrazine, substituted pyrimidine, substituted pyridazine, substituted quinoline, substituted isoquinoline, substituted benzoquinoline, substituted quinoxaline, substituted quinazoline, substituted carbazol, substituted benzoimidazole, substituted benzofuran, substituted benzothiophene, substituted isobenzothiophene, substituted benzooxazole, substituted isobenzooxazole, substituted triazole, substituted oxadiazole, substituted triazine, substituted dibenzofuran, and substituted dibenzothiophene may be selected from 
     a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, 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, —N(Q 401 )(Q 402 ), —Si(Q 403 )(Q 404 )(Q 405 ), and —B(Q 406 )(Q 407 ); 
     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 heterocondensed polycyclic group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, 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 heterocondensed polycyclic group, —N(Q 411 )(Q 412 ), —Si(Q 413 )(Q 414 )(Q 415 ), and —B(Q 416 )(Q 417 ); and 
     —N(Q 421 )(Q 422 ), —Si(Q 423 )(Q 424 )(Q 425 ), or —B(Q 426 )(Q 427 ); 
     L 401  may be an organic ligand; 
     xc1 may be 1, 2, or 3; and 
     xc2 may be 0, 1, 2, or 3. 
     L 401  may be a monovalent, divalent, or trivalent organic ligand. For example, L 401  may be selected from a halogen ligand (for example, Cl or F), a diketone ligand (for example, acetylacetonate, 1,3-diphenyl-1,3-propandionate, 2,2,6,6-tetramethyl-3,5-heptandionate, or hexafluoroacetonate), a carboxylic acid ligand (for example, picolinate, dimethyl-3-pyrazolecarboxylate, or benzoate), a carbon monooxide ligand, an isonitrile ligand, a cyano ligand, and a phosphorous ligand (for example, phosphine, and phosphaite), but is not limited thereto. 
     When A 401  in Formula 401 has two or more substituents, the substituents of A 402  may bind to each other to form a saturated or unsaturated ring. 
     When A 402  in Formula 402 has two or more substituents, the substituents of A 402  may bind to each other to form a saturated or unsaturated ring. 
     When xc1 in Formula 401 is two or more, a plurality of ligands 
                         
in Formula 401 may be identical or different. When xc1 in Formula 401 is two or more, A 401  and A 402  may be respectively directly connected to A 401  and A 402  of other neighboring ligands with or without a linker (for example, a C 1 -C 5  alkylene, or —N(R′)— (wherein R′ may be a C 1 -C 10  alkyl group or a C 6 -C 20  aryl group) or —C(═O)—) therebetween.
 
     In an implementation, the phosphorescent dopant may include at least one of Compounds PD1 to PD74 below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In an implementation, the phosphorescent dopant may include PtOEP. 
     
       
         
         
             
             
         
       
     
     In an implementation, the fluorescent dopant may include at least one selected from DPAVBi, BDAVBi, TBPe, DCM, DCJTB, Coumarin 6, and C545T. 
     
       
         
         
             
             
         
       
     
     In an implementation, the fluorescent dopant may include a compound represented by Formula 501 below. 
     
       
         
         
             
             
         
       
     
     In Formula 501, 
     Ar 501  may be selected from: 
     a naphthalene group, a heptalene group, a fluorenene group, a spiro-fluorenene group, a benzofluorenene group, a dibenzofluorenene 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, and an indenoanthracene group; 
     a naphthalene group, a heptalene group, a fluorenene group, a spiro-fluorenene group, a benzofluorenene group, a dibenzofluorenene group, a phenalene group, a phenanthrene group, a 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, and an indenoanthracene group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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, 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, 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, and —Si(Q 501 )(Q 502 )(Q 503 ) (wherein Q 501  to Q 503  are each independently selected from a hydrogen, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  aryl group, and a C 1 -C 60  heteroaryl group); 
     L 501  to L 503  may be the same as defined in connection with L 201 ; 
     R 501  and R 502  may each independently be selected from: 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and 
     a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; 
     xd1 to xd3 may each independently be selected from 0, 1, 2, and 3; and 
     xb4 may be selected from 1, 2, 3, and 4. 
     The fluorescent host may include at least one of Compounds FD1 to FD9 illustrated below. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     An amount of the dopant in the emission layer may be, e.g., in a range of about 0.01 to about 15 parts by weight, based on 100 parts by weight of the host, but is not limited thereto. 
     A thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å, e.g., about 200 Å to about 600 Å. When the thickness of the emission layer is within this range, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage. 
     Then, an electron transport region may be disposed on the emission layer. 
     The electron transport region may include at least one selected from a hole blocking layer, an electron transport layer (ETL), and an electron injection layer. 
     For example, the electron transport region may have a structure of electron transport layer/electron injection layer or a structure of hole blocking layer/electron transport layer/electron injection layer, wherein layers of each structure may be sequentially stacked from the emission layer in the stated order. 
     According to an embodiment, the organic layer  150  of the organic light-emitting device may include an electron transport region disposed between the emission layer and the second electrode  190 , and the electron transport region may include at least one condensed cyclic compound represented by Formula 1. 
     The electron transport region may include a hole blocking layer. The hole blocking layer may be formed, when the emission layer includes a phosphorescent dopant, to help prevent diffusion of excitons or holes into an electron transport layer. 
     When the electron transport region includes a hole blocking layer, the hole blocking layer may be formed on the emission layer by using various methods, e.g., vacuum deposition, spin coating casting, a LB method, ink-jet printing, laser-printing, or laser-induced thermal imaging. When the hole blocking layer is formed by vacuum deposition or spin coating, deposition and coating conditions for the hole blocking layer may be determined by referring to the deposition and coating conditions for the hole injection layer. 
     The hole blocking layer may include, e.g., BCP or Bphen. 
     
       
         
         
             
             
         
       
     
     A thickness of the hole blocking layer may be in a range of about 20 Å to about 1,000 Å, e.g., about 30 Å to about 300 Å. When the thickness of the hole blocking layer is within these ranges, the hole blocking layer may have improved hole blocking ability without a substantial increase in driving voltage. 
     The electron transport region may include an electron transport layer. The electron transport layer may be formed on the emission layer or the hole blocking layer by using various methods, e.g., vacuum deposition, spin coating casting, a LB method, ink-jet printing, laser-printing, or laser-induced thermal imaging. When an electron transport layer is formed by vacuum deposition or spin coating, deposition and coating conditions for the electron transport layer may be determined by referring to the deposition and coating conditions for the hole injection layer. 
     According to an embodiment, the organic layer  150  of the organic light-emitting device may include the electron transport region disposed between the emission layer and the second electrode  190 , and the electron transport region may include the electron transport layer. The electron transport layer may include at least one compound represented by Formula 1. 
     The electron transport layer may further include, in addition to the condensed cyclic compound represented by Formula 1, at least one selected from BCP, Bphen, and Alg 3 , BAlq, and NTAZ, which are illustrated below. 
     
       
         
         
             
             
         
       
     
     A thickness of the electron transport layer may be in a range of about 100 Å to about 1,000 Å, e.g., about 150 Å to about 500 Å. When the thickness of the electron transport layer is within the range described above, the electron transport layer may have satisfactory electron transport characteristics without a substantial increase in driving voltage. 
     In an implementation, the electron transport layer may further include, in addition to the materials described above, a metal-containing material. 
     The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium quinolate, LiQ) or ET-D2. 
     
       
         
         
             
             
         
       
     
     The electron transport region may include an electron injection layer that allows electrons to be easily provided from the second electrode  190 . 
     The electron injection layer may be formed on the electron transport layer by using various methods, e.g., vacuum deposition, spin coating casting, a LB method, ink-jet printing, laser-printing, or laser-induced thermal imaging. When an electron injection layer is formed by vacuum deposition or spin coating, deposition and coating conditions for the electron injection layer may be determined by referring to the deposition and coating conditions for the hole injection layer. 
     The electron injection layer may include at least one selected from, LiF, NaCl, CsF, Li 2 O, BaO, and LiQ. 
     A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, e.g., about 3 Å to about 90 Å. When the thickness of the electron injection layer is within the range described above, the electron injection layer may have satisfactory electron injection characteristics without a substantial increase in driving voltage. 
     The second electrode  190  may be disposed on the organic layer  150  having such a structure. The second electrode  190  may be a cathode, e.g., an electron injection electrode, and in this regard, a material for forming the second electrode  190  may be a material having a low work function, and such a material may be metal, alloy, an electrically conductive compound, or a mixture thereof. Detailed examples of the second electrode  190  may include lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag). In an implementation, the material for forming the second electrode  190  may be ITO or IZO. The second electrode  190  may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. 
     Hereinbefore, the organic light-emitting device has been described with reference to  FIG. 1 , but is not limited thereto. 
     A C 1 -C 60  alkyl group used herein refers to a linear or branched aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms, and detailed examples thereof are a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a ter-butyl group, a pentyl group, an iso-amyl group, and a hexyl group. A C 1 -C 60  alkylene group used herein refers to a divalent group having the same structure as the C 1 -C 60  alkyl group. 
     A C 1 -C 60  alkoxy group used herein refers to a monovalent group represented by —OA 101  (wherein A 101  is the C 1 -C 60  alkyl group), and detailed examples thereof are a methoxy group, an ethoxy group, and an isopropyloxy group. 
     A C 2 -C 60  alkenyl group used herein refers to a hydrocarbon group formed by substituting at least one carbon double bond in the middle or terminal of the C 2 -C 60  alkyl group, and detailed examples thereof are an ethenyl group, a prophenyl group, and a butenyl group. A C 2 -C 60  alkylene group used herein refers to a divalent group having the same structure as the C 2 -C 60  alkyl group. 
     A C 2 -C 60  alkynyl group used herein refers to a hydrocarbon group formed by substituting at least one carbon trip bond in the middle or terminal of the C 2 -C 60  alkyl group, and detailed examples thereof are an ethynyl group, and a propynyl group. A C 2 -C 60  alkylene group used herein refers to a divalent group having the same structure as the C 2 -C 60  alkyl group. 
     A C 3 -C 10  cycloalkyl group used herein refers to a monovalent hydrocarbon monocyclic group having 3 to 10 carbon atoms, and detailed examples thereof are a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. A C 3 -C 10  cycloalkylene group used herein refers to a divalent group having the same structure as the C 3 -C 10  cycloalkyl group. 
     A C 1 -C 10  heterocycloalkyl group used herein refers to a monovalent monocyclic group having at least one hetero atom selected from N, O, P, and S as a ring-forming atom and 1 to 10 carbon atoms, and detailed examples thereof are a tetrahydrofuranyl group, and a tetrahydrothiophenyl group. A C 1 -C 10  heterocycloalkylene group used herein refers to a divalent group having the same structure as the C 1 -C 10  heterocycloalkyl group. 
     A C 3 -C 10  cycloalkenyl group used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one double bond in the ring thereof and does not have aromacity, and detailed examples thereof are a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. A C 3 -C 10  cycloalkenylene group used herein refers to a divalent group having the same structure as the C 3 -C 10  cycloalkenyl group. 
     A C 1 -C 10  heterocycloalkenyl group used herein refers to a monovalent monocyclic group that has at least one hetero atom selected from N, O, P, and S as a ring-forming atom, 1 to 10 carbon atoms, and at least one double bond in its ring. Detailed examples of the C 1 -C 10  heterocycloalkenyl group are a 2,3-hydrofuranyl group and a 2,3-hydrothiophenyl group. A C 1 -C 10  heterocycloalkenylene group used herein refers to a divalent group having the same structure as the C 1 -C 10  heterocycloalkenyl group. 
     A C 6 -C 60  aryl group used herein refers to a monovalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms, and a C 6 -C 60  arylene group used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Detailed examples of the C 6 -C 60  aryl group are 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 include two or more rings, the rings may be fused to each other. 
     A C 1 -C 60  heteroaryl group used herein refers to a monovalent group having a carboncyclic aromatic system that has at least one hetero atom selected from N, O, P, and S as a ring-forming atom, and 1 to 60 carbon atoms. A C 1 -C 60  heteroarylene group used herein refers to a divalent group having a carbocyclic aromatic system that has at least one hetero atom selected from N, O, P, and S as a ring-forming atom, and 1 to 60 carbon atoms. Examples of the C 1 -C 60  heteroaryl group are 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 include two or more rings, the rings may be fused to each other. 
     A C 6 -C 60  aryloxy group used herein indicates -QA 102  (wherein A 102  is the C 6 -C 60  aryl group), and a C 6 -C 60  arylthio group used herein indicates —SA 103  (wherein A 103  is the C 6 -C 60  aryl group). 
     A monovalent non-aromatic condensed polycyclic group used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) that has two or more rings condensed to each other, only carbon atoms as a ring forming atom, and non-aromacity in the entire molecular structure. A detailed example of the monovalent non-aromatic condensed polycyclic group is a fluorenyl group. A divalent non-aromatic condensed polycyclic group used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed polycyclic group. 
     A monovalent non-aromatic condensed heteropolycyclic group used herein refers to a momovalent group (for example, having 1 to 60 carbon atoms) that has two or more rings condensed to each other, has a heteroatom selected from N, O P, and S, other than carbon atoms, as a ring forming atom, and has non-aromacity in the entire molecular structure. An example of the monovalent non-aromatic condensed heteropolycyclic group is a carbazolyl group. A divalent non-aromatic condensed heteropolycyclic group used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycyclic group. 
     at least one substituent selected from substituents of the substituted C 3 -C 10  cycloalkylene group, substituted C 1 -C 10  heterocycloalkylene group, substituted C 3 -C 10  cycloalkenylene group, substituted C 1 -C 10  heterocycloalkenylene group, substituted C 6 -C 60  arylene group, substituted C 1 -C 60  heteroarylene group, substituted divalent non-aromatic condensed polycyclic group, substituted divalent non-aromatic condensed heteropolycyclic group, substituted C 1 -C 60  alkyl group, substituted C 2 -C 60  alkenyl group, substituted C 2 -C 60  alkynyl group, substituted C 1 -C 60  alkoxy group, substituted C 3 -C 10  cycloalkyl group, substituted C 1 -C 10  heterocycloalkyl group, substituted C 3 -C 10  cycloalkenyl group, substituted C 1 -C 10  heterocycloalkenyl group, substituted C 6 -C 60  aryl group, substituted C 6 -C 60  aryloxy group, substituted C 6 -C 60  arylthio group, substituted C 1 -C 60  heteroaryl group, substituted monovalent non-aromatic condensed polycyclic group, and substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from 
     a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, 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 heterocondensed polycyclic 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 heterocondensed polycyclic group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, 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 heterocondensed polycyclic group, —S(Q 21 )(Q 22 )(Q 23 ), —B(Q 24 )(Q 25 ), and —N(Q 26 )(Q 27 ); and 
     —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 34 )(Q 35 ), and —N(Q 36 )(Q 37 ); 
     wherein Q 21  to Q 27 , and Q 31  to Q 37  may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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, and a monovalent non-aromatic condensed heteropolycyclic group. 
     For example, at least one substituent of the substituted C 3 -C 10  cycloalkylene group, substituted C 1 -C 10  heterocycloalkylene group, substituted C 3 -C 10  cycloalkenylene group, substituted C 1 -C 10  heterocycloalkenylene group, substituted C 6 -C 60  arylene group, substituted C 1 -C 60  heteroarylene group, substituted divalent non-aromatic condensed polycyclic group, substituted divalent non-aromatic condensed heteropolycyclic group, substituted C 1 -C 60  alkyl group, substituted C 2 -C 60  alkenyl group, substituted C 2 -C 60  alkynyl group, substituted C 1 -C 60  alkoxy group, substituted C 3 -C 10  cycloalkyl group, substituted C 1 -C 10  heterocycloalkyl group, substituted C 3 -C 10  cycloalkenyl group, substituted C 1 -C 10  heterocycloalkenyl group, substituted C 6 -C 60  aryl group, substituted C 6 -C 60  aryloxy group, substituted C 6 -C 60  arylthio group, substituted C 1 -C 60  heteroaryl group, substituted monovalent non-aromatic condensed polycyclic group, and substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from 
     a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isooxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzooxazolyl group, an isobenzooxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; 
     a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzooxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; 
     a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isooxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzooxazolyl group, an isobenzooxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isooxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzooxazolyl group, an isobenzooxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, —Si(Q 21 )(Q 22 )(Q 23 ), —B(Q 24 )(Q 25 ), and —N(Q 26 )(Q 27 ); and 
     —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 34 )(Q 35 ), and —N(Q 36 )(Q 37 ); 
     Q 21  to Q 27 , Q 31  to Q 37 , and Q 31  to Q 37  may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, 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 cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, 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 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 pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl 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 benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group. 
     The term “CN” used herein refers to a cyano group, the term “Ph” used herein refers to a phenyl group, “Me” used herein refers to a methyl group, the term “Et” used herein refers to an ethyl group, and the term “ter-Bu” or “Bu t ” used herein refers to a tert-butyl group. 
     Hereinafter, an organic light-emitting device according to an embodiment will be described in detail with reference to Synthesis Examples and Examples. The wording “B was used instead of A” used in describing Synthesis Examples means that a molar equivalent of A was identical to a molar equivalent of B. 
     The following Examples and Comparative Examples are provided in order to highlight characteristics of one or more embodiments, but it will be understood that the Examples and Comparative Examples are not to be construed as limiting the scope of the embodiments, nor are the Comparative Examples to be construed as being outside the scope of the embodiments. Further, it will be understood that the embodiments are not limited to the particular details described in the Examples and Comparative Examples. 
     EXAMPLE 
     Synthesis Example 1: Synthesis of Compound 1 
     
       
         
         
             
             
         
       
     
     Synthesis of Intermediate I-1 
     2,3-dihydroxynaphthalene (8.0 g, 50 mmol) and a methansulfonic acid (16.2 mL, 250 mmol) were dissolved in o-xylene (200 mL), and then the result was stirred at a temperature of 130° C. for 24 hours. The reaction solution was cooled to ambient temperature, and then, a sodium bicarbonate aqueous solution was added thereto. An extraction process was performed thereon three times with 60 mL of chloroform. An obtained organic layer was dried using magnesium sulfate, and a solvent was removed therefrom by evaporation. The residual was separation-purified by silica gel column chromatography to obtain 2.35 g (yield of 33%) of Intermediate I-1. The obtained compound was confirmed by LC-MS. C 20 H 12 O 2 : M+1 285.1 
     Synthesis of Intermediate I-2 
     2.35 g (8.3 mmol) of Intermediate I-1 was dissolved in 20 mL of toluene and 20 mL of 30% potassium phosphate, and then, at a temperature of 0° C., 2.82 g (10.0 mmol) of trifluoromethansulfonic acid anhydride was slowly added dropwise thereto. The reaction solution was heated to ambient temperature, and then stirred for 3 hours. Then, 30 mL of water was added thereto, and an extraction process was performed thereon three times by using 30 mL of ethyl ether. An obtained organic layer was dried using magnesium sulfate, and a solvent was removed therefrom by evaporation. The residual was separation-purified by silica gel column chromatography to obtain 2.80 g (yield of 81%) of Intermediate I-2. The obtained compound was confirmed by LC-MS. C 21 H 11 F 3 O 4 S: M+1 417.0 
     Synthesis of Intermediate I-3 
     2.80 g (6.72 mmol) of Intermediate I-2, 1.71 g (6.72 mmol) of bis(pinacolato)diborane, 0.24 g (0.34 mmol) of [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium (II) (hereinafter referred to as PdCl 2 (dppf) 2 ), and 1.98 g (20.2 mmol) of KOAc were dissolved in 40 ml of DMSO. Then, the result was stirred at a temperature of 80° C. for 6 hours. When the reaction solution was cooled to ambient temperature, the reaction solution was extracted three times with 40 ml of water and 40 ml of diethyl ether. An obtained organic layer was dried by using magnesium sulfate, and then a solvent was removed therefrom by evaporation. The residual was separation-purified by silica gel column chromatography to obtain 1.99 g (yield of 75%) of Intermediate I-3. The obtained compound was confirmed by LC-MS. C 26 H 23 BO 3 : M+1 395.2 
     Synthesis of Compound 1 
     1.99 g (5.05 mmol) of Intermediate I-3, 1.57 g (5.05 mmol) of 2-bromo-4,6-diphenyl pyrimidine, 0.29 g (0.25 mmol) of Pd(PPh 3 ) 4 , and 2.10 g (15.2 mmol) of K 2 CO 3  were dissolved 60 mL of in a THF/H 2 O (a volumetric ratio of 2/1) mixed solution. Then, at a temperature of 80° C., the resultant solution was stirred for 12 hours. The reaction solution was cooled to ambient temperature, and then, extracted three times by using 30 mL of water and 30 mL of ethyl acetate. An obtained organic layer was dried by using magnesium sulfate, and then a solvent was removed therefrom by evaporation. The residual was separation-purified by silica gel column chromatography to obtain 1.91 g (yield of 76%) of Compound 1. The obtained compound was identified by MS/FAB and  1 H NMR. C 36 H 22 N 2 O cal. 498.17. found 498.18. 
     Synthesis Example 2: Synthesis of Compound 2 
     
       
         
         
             
             
         
       
     
     1.84 g (yield of 73%) of Compound 2 was obtained in the same manner as in Synthesis Example 1, except that in synthesizing Compound 1, chloro-1,3,5-triazine was used instead of 2-bromo-4,6-diphenyl pyrimidine. The obtained compound was identified by MS/FAB and  1 H NMR. C 35 H 21 N 3 O cal. 499.17. found 499.19. 
     Synthesis Example 3: Synthesis of Compound 9 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Synthesis of Intermediate I-4 
     5.02 g (30 mmol) of 9H-carbazole, 4.71 g (30 mmol) of bromobenzene, 1.14 g (18 mmol) of copper powder, and 6.22 g (45 mmol) of K 2 CO 3  were dissolved in 80 mL of o-dichlorobenzene. Then, the result was stirred at a temperature of 180° C. for 24 hours. The reaction solution was cooled to ambient temperature, 60 mL of water was added thereto, and then an extraction process was performed thereon three times by using 50 mL of ethyl acetate. An obtained organic layer was dried by using magnesium sulfate, and the residual obtained by evaporating a solvent therefrom was separation-purified by silica gel column chromatography to obtain 5.47 g (yield of 75%) of Intermediate I-4. The obtained compound was confirmed by LC-MS. C 18 H 13 N: M+1 244.1 
     Synthesis of Intermediate I-5 
     5.47 g (22.5 mmol) of Intermediate I-4 was completely dissolved in 80 mL of CH 2 Cl 2 , and then, 4.00 g (22.5 mmol) of N-bromosuccinimide was added thereto, and the resultant solution was stirred at ambient temperature for 12 hours. 60 mL of water was added to the reaction solution and then an extraction was performed thereon three times by using 50 mL of CH 2 Cl 2 . An obtained organic layer was dried by using magnesium sulfate, and then, a solvent was evaporated therefrom. Then, recrystallization of the resultant solution was performed by using methanol to obtain 6.16 g (yield of 85%) of Intermediate I-5. The obtained compound was confirmed by LC-MS. C 18 H 12 BrN: M+1 322.0 
     Synthesis of Intermediate I-6 
     6.16 g (19.1 mmol) of Intermediate I-5 and 2.57 g (28.7 mmol) of CuCN were dissolved in 70 mL of DMF, and then, the result was stirred at a temperature of 150° C. for 24 hours. The reaction solution was cooled to ambient temperature, and then, 60 mL of ammonia water and 60 mL of water were added thereto. An extraction process was performed thereon three times by using 50 mL of CH 2 Cl 2 . An obtained organic layer was dried by using magnesium sulfate, and the residual obtained by evaporating a solvent therefrom was separation-purified by silica gel column chromatography to obtain 4.71 g (yield of 92%) of Intermediate I-6. The obtained compound was confirmed by LC-MS. C 19 H 12 N 2 : M+1 269.1 
     Synthesis of Intermediate I-7 
     4.71 g (17.6 mmol) of Intermediate I-6 was completely dissolved in 80 mL of CH 2 Cl 2 , and then, 3.13 g (17.6 mmol) of N-bromosuccinimide was added thereto, and the resultant solution was stirred at room temperature for 8 hours. 60 mL of water was added to the reaction solution and then an extraction was performed thereon three times by using 50 mL of CH 2 Cl 2 . An organic layer was dried by using magnesium sulfate, and then, a solvent was evaporated therefrom, and then, recrystallization of the resultant solution was performed by using methanol to obtain 5.81 g (yield 95%) of Intermediate I-7. The obtained compound was confirmed by LC-MS. C 19 H 11 BrN 2 : M+1 347.0 
     Synthesis of Intermediate I-8 
     5.81 g (16.7 mmol) of Intermediate I-7, 0.68 g (0.84 mmol) of Pd(dppf) 2 Cl 2 , and 4.92 g (50.1 mmol) of KOAc were dissolved in 80 mL of DMSO, and then the resultant solution was stirred at a temperature of 150° C. for 24 hours. The reaction solution was cooled to ambient temperature, and 100 mL of water was added thereto. Then, the resultant reaction solution was extracted three times by using 50 mL of CH 2 Cl 2 . An obtained organic layer was dried by using magnesium sulfate, and the residue obtained by evaporating a solvent therefrom was separation-purified by silica gel column chromatography to obtain 4.61 g (yield of 70%) of Intermediate I-8. The obtained compound was confirmed by LC-MS. C 25 H 23 BN 2 O 2 : M+1 395.2 
     Synthesis of Compound 9 
     1.84 g (yield of 73%) of Compound 9 was obtained in the same manner as in Synthesis Example 1, except that in synthesizing Compound 1, Intermediate I-2 was used instead of Intermediate I-3, and Intermediate I-8 was used instead of 2-bromo-4,6-diphenyl Pyrimidine. The obtained compound was identified by MS/FAB and  1 H NMR. C 39 H 22 N 2 O cal. 534.17. found 534.16. 
     Synthesis Example 4: Synthesis of Compound 25 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Synthesis of Intermediate I-9 
     2.07 g (10 mmol) of 1-bromonaphthalene was dissolved in 30 mL of THF. Then, at a temperature of −78° C., 4 mL (2.5M in hexane) of n-butyllithium was added thereto. 1 hour after the addition, at the same temperature, 2.0 mL (10 mmol) of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was added thereto. The result was stirred at ambient temperature for 5 hours, water was added thereto, and washed three times with diethyl ether (30 mL). The washed diethyl ether layer was dried by using MgSO 4  and then evaporated under reduced pressure to obtain a product, which was then separation-purified by silica gel column chromatography to obtain 1.96 g (yield of 77%) of Intermediate I-9. The obtained compound was confirmed by LC-MS. C 16 H 19 BO 2 : M+1 255.2 
     Synthesis of Intermediate I-10 
     2.54 g (10.0 mmol) of Intermediate I-9, 2.02 g (10.0 mmol) of 1-bromo-2-nitrobenzene, 0.58 g (0.50 mmol) of Pd(PPh 3 ) 4 , 0.16 g (0.5 mmol) of tetrabutylammonium bromide (TBAB), and 3.18 g (30.0 mmol) of Na 2 CO 3  were dissolved in 60 mL of a toluene/ethanol/H 2 O (3/3/1) mixed solution, and then, the mixture was stirred at a temperature of 80° C. for 16 hours. The reaction solution was cooled to ambient temperature, and then, an extraction process was performed thereon three times by using 60 mL of water and 60 mL of diethyl ether. An organic layer obtained therefrom was dried by using magnesium sulfate and the residual obtained by evaporating a solvent therefrom was separation-purified by silica gel column chromatography to obtain 2.04 g (yield: 82%) of Intermediate I-10. The obtained compound was confirmed by LC-MS. C 16 H 11 NO 2 : M+1 250.1 
     Synthesis of Intermediate I-11 
     2.49 g (10.0 mmol) of Intermediate I-10, 3.56 g (30 mmol) of tin, and 5 mL (50 mmol, conc. 36.5%) of a hydrochloric acid were dissolved in 60 mL of ethanol, and then the result was stirred at a temperature of 100° C. for 8 hours. The reaction solution was cooled to ambient temperature, and 3 g of sodium hydroxide dissolved in 10 mL of water was added to a filtrate obtained by performing filtration under reduced pressure, and an extraction process was performed thereon three times by using 60 mL of water and 60 mL of dichloromethane. An organic layer obtained therefrom was dried by using magnesium sulfate and the residue obtained by evaporating a solvent therefrom was separation-purified by silica gel column chromatography to obtain 1.97 g (yield: 90%) of Intermediate I-11. The obtained compound was confirmed by LC-MS. C 16 H 13 N: M+1 220.1 
     Synthesis of Intermediate I-12 
     2.19 g (10 mmol) of Intermediate I-11 and 3.66 g (20 mmol) of 3-bromobenzaldehyde were dissolved in 10 mL of a trifluoroacetic acid, and then the result was stirred in a seal tube at a temperature of 130° C. for 3 days. The reaction solution was cooled to ambient temperature, and then subjected to quenching using NaHCO 3 , and then an extraction process was performed thereon three times by using 60 mL of water and 60 mL of dichloromethane. An organic layer obtained therefrom was dried by using magnesium sulfate and the residue obtained by evaporating a solvent therefrom was separation-purified by silica gel column chromatography to obtain 1.92 g (yield: 50%) of Intermediate I-12. The obtained compound was confirmed by LC-MS. C 23 H 14 BrN: M+1 384.0 
     Synthesis of Intermediate I-13 
     3.15 g (yield of 73%) of Intermediate I-13 was obtained in the same manner as used to synthesize Intermediate I-9, except that in synthesizing Intermediate I-9, Intermediate I-12 was used instead of 1-bromonaphthalene. The obtained compound was confirmed by LC-MS. C 29 H 26 BNO 2 : M+1 432.2 
     Synthesis of Compound 25 
     2.25 g (yield of 78%) of Compound 25 was obtained in the same manner as used to synthesize Compound 9, except that Intermediate I-13 was used instead of Intermediate I-8. The obtained compound was identified by MS/FAB and  1 H NMR. C 43 H 25 NO cal. 571.19. found 571.20. 
     Synthesis Example 5: Synthesis of Compound 60 
     
       
         
         
             
             
         
       
     
     Synthesis of Intermediate I-14 
     2.36 g (10 mmol) of 1,3-dibromobenzene was dissolved in 30 mL of THF, and then, at a temperature of −78° C., 4 mL (2.5M in hexane) of n-butyllithium was added thereto. 1 hour after the addition, 2.20 g (10 mmol) of chlorodiphenylphosphine was slowly added dropwise thereto. Then, the result was stirred for 3 hours, the temperature was raised to ambient temperature, and water was added thereto. The result solution was washed three times with ethyl acetate (30 mL). The obtained ethyl acetate layer was dried by using MgSO 4 , and then separation-purified by silica gel column chromatography to obtain 2.73 g (yield of 80%) of Intermediate I-14. The obtained compound was confirmed by LC-MS. C 18 H 14 BrP: M+1 341.0 
     Synthesis of Intermediate I-15 
     2.06 g (yield of 53%) of Intermediate I-15 was obtained in the same manner as used to synthesize Intermediate I-9, except that in synthesizing Intermediate I-9, Intermediate I-14 was used instead of 1-bromonaphthalene. The obtained compound was confirmed by LC-MS. C 24 H 26 BO 2 P: M+1 389.2 
     Synthesis of Intermediate I-16 
     2.47 g (yield of 53%) of Intermediate I-16 was obtained in the same manner as used to synthesize Compound 1, except that in synthesizing Compound 1, Intermediate I-15 was used instead of Intermediate I-3 and 1,4-dibromonaphthalene was used instead of 2-bromo-4,6-diphenyl pyrimidine. The obtained compound was confirmed by LC-MS. C 28 H 20 BrP: M+1 467.1 
     Synthesis of Intermediate I-17 
     2.65 g (yield of 80%) of Intermediate I-17 was obtained in the same manner as used to synthesize Compound 1, except that in synthesizing Compound 1, Intermediate I-16 was used instead of 2-bromo-4,6-diphenyl pyrimidine. The obtained compound was confirmed by LC-MS. C 48 H 31 OP: M+1 655.2 
     Synthesis of Compound 60 
     2.65 g (4.05 mmol) of Intermediate I-17 was dissolved in 25 mL of dichloromethane, and then, 2 mL of hydrogen peroxide was added thereto, and the result was stirred at ambient temperature for 20 hours. 20 mL of water was added thereto, and an extraction process was performed thereon three times by using 20 mL of dichloromethane. An obtained organic layer was dried using magnesium sulfate and a solvent was removed therefrom by evaporation. The residue was separation-purified by silica gel column chromatography to obtain 2.04 g (yield of 75%) of Intermediate I-60. The obtained compound was identified by MS/FAB and  1 H NMR. C 48 H 31 O 2 P cal. 670.21. found 670.20. 
     Synthesis Example 6: Synthesis of Compound 72 
     
       
         
         
             
             
         
       
     
     2.36 g (yield of 82%) of Compound 72 was obtained in the same manner as used to synthesize Compound 1, except that in synthesizing Compound 1, Intermediate I-18 was used instead of 2-bromo-4,6-diphenyl pyrimidine. The obtained compound was identified by MS/FAB and  1 H NMR. C 44 H 26 O cal. 570.20. found 570.19. 
     Additional compounds were synthesized by appropriate intermediate materials by using the same synthesis method as described above, and  1 H NMR and MS/FAB results of the synthetic compounds are shown in Table 1 below. 
     Methods of synthesizing compounds other than the compound shown in Table 1 may be understood by referring to the synthesis path and source materials described above. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 MS/FAB 
               
            
           
           
               
               
               
               
            
               
                 Compound 
                   1 H NMR (CDC1 3 , 400 MHz) 
                 found 
                 calc. 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 1 
                 □□□δ = 9.03-9.02 (m, 1H), 8.88-8.86 (dd, 1H), 8.40 (s, 1H), 8.32- 
                 498.18 
                 498.17 
               
               
                   
                 8.30 (m, 4H), 8.19-8.17 (m, 1H), 8.10-8.06 (m, 2H), 7.98 (s, 1H), 
               
               
                   
                 7.97-7.95 (m, 1H), 7.84-7.80 (m, 1H), 7.62-7.49 (m, 6H), 7.43-7.39 
               
               
                   
                 (m, 1H), 7.31-7.26 (m, 2H) 
               
               
                 2 
                 □□□δ = 9.11-9.10 (m, 1H), 8.89-8.86 (m, 1H), 8.73-8.71 (m, 4H), 
                 499.19 
                 499.17 
               
               
                   
                 8.49 (s, 1H), 8.20-8.18 (m, 1H), 8.10-8.07 (m, 2H), 7.97-7.95 (m, 
               
               
                   
                 1H), 7.84-7.80 (m, 1H), 7.62-7.51 (m, 6H), 7.44-7.40 (m, 3H) 
               
               
                 6 
                 □□□δ = 8.80-8.78 (m, 1H), 8.76-8.74 (m, 1H), 8.48-8.55 (m, 1H), 
                 421.16 
                 421.15 
               
               
                   
                 8.53-8.52 (m, 1H), 8.21-8.20 (m, 2H), 8.08-8.06 (m, 2H), 8.02-7.95 
               
               
                   
                 (m, 3H), 7.84-7.77 (m, 2H), 7.71-7.68 (m, 1H), 7.62-7.58 (m, 2H), 
               
               
                   
                 7.46-7.39 (m, 3H) 
               
               
                 9 
                 □□□δ = 8.76-8.74 (m, 1H), 8.67-8.66 (m, 1H), 8.52-8.51 (m, 1H), 
                 534.16 
                 534.17 
               
               
                   
                 8.46-8.45 (m, 1H), 8.31-8.30 (m, 1H), 8.08-8.05 (m, 2H), 7.99-7.94 
               
               
                   
                 (m, 2H), 7.85-7.78 (m, 3H), 7.71-7.69 (dd, 1H), 7.62-7.58 (m, 1H), 
               
               
                   
                 7.53-7.41 (m, 6H), 7.32-7.26 (m, 2H) 
               
               
                 11 
                 □□□δ = 8.76-8.73 (m, 1H), 8.58-8.57 (m, 1H), 8.51-8.50 (m, 1H), 
                 649.18 
                 649.17 
               
               
                   
                 8.31-8.28 (m, 2H), 8.08-8.05 (m, 2H), 8.01-7.93 (m, 6H), 7.89-7.80 
               
               
                   
                 (m, 1H), 7.85-7.80 (m, 2H), 7.62-7.57 (m, 2H), 7.54-7.40 (m, 8H), 
               
               
                   
                 7.34-7.27 (m, 1H) 
               
               
                 17 
                 □□□δ = 8.78-8.76 (m, 1H), 8.60-8.59 (m, 1H), 8.54-8.53 (m, 1H), 
                 485.20 
                 485.18 
               
               
                   
                 8.26-8.18 (m, 2H), 8.08-8.06 (m, 2H), 7.98-7.96 (m, 2H), 7.86-7.84 
               
               
                   
                 (m, 1H), 7.72-7.61 (m, 3H), 7.47-7.40 (m, 2H), 7.16-7.13 (m, 2H), 
               
               
                   
                 1.32 (s, 6H) 
               
               
                 22 
                 □□□δ = 8.86-8.85 (m, 1H), 8.80-8.78 (m, 1H), 8.68-8.66 (m, 1H), 
                 571.18 
                 571.19 
               
               
                   
                 8.52-8.49 (m, 2H), 8.45-8.44 (m, 1H), 8.27-8.26 (m, 1H), 8.11-8.06 
               
               
                   
                 (m, 2H), 8.01-7.92 (m, 5H), 7.85-7.80 (m, 2H), 7.74-7.70 (m, 2H), 
               
               
                   
                 7.67-7.58 (m, 4H), 7.47-7.39 (m, 3H) 
               
               
                 25 
                 □□□δ = 8.78-8.72 (m, 2H), 8.63-8.61 (m, 1H), 8.55-8.51 (m, 2H), 
                 571.20 
                 571.19 
               
               
                   
                 8.47-8.44 (m, 1H), 8.32-8.31 (m, 1H), 8.28-8.26 (m, 1H), 8.08-8.05 
               
               
                   
                 (m, 2H), 7.99-7.91 (m, 3H), 7.87-7.79 (m, 4H), 7.72-7.65 (m, 2H), 
               
               
                   
                 7.62-7.58 (m, 1H), 7.49-7.39 (m, 5H) 
               
               
                 30 
                 □□□δ = 8.76-8.74 (m, 1H), 8.50-8.49 (m, 1H), 8.24-8.21 (m, 5H), 
                 573.20 
                 573.21 
               
               
                   
                 8.15 (s, 2H), 8.08-8.05 (m, 2H), 8.01-7.95 (m, 4H), 7.88-7.80 (m, 
               
               
                   
                 3H), 7.62-7.58 (m, 1H), 7.47-7.39 (m, 6H), 7.33-7.31 (m, 2H) 
               
               
                 38 
                 □□□δ = 8.77-8.75 (m, 1H), 8.49-8.48 (m, 1H), 8.24-8.20 (m, 2H), 
                 785.26 
                 785.25 
               
               
                   
                 8.09-8.04 (m, 4H), 8.02-8.00 (m, 1H), 7.97-7.94 (m, 2H), 7.84-7.78 
               
               
                   
                 (m, 3H), 7.70-7.58 (m, 7H), 7.52-7.39 (m, 14H), 7.34-7.27 (m, 1H) 
               
               
                 47 
                 □□□δ = 8.84-8.82 (m, 1H), 8.79 (d, 1H), 8.70-8.69 (m, 1H), 8.51- 
                 527.12 
                 527.13 
               
               
                   
                 8.50 (m, 1H), 8.39-8.38 (m, 1H), 8.14-8.04 (m, 5H), 7.97-7.90 (m, 
               
               
                   
                 3H), 7.84-7.75 (m, 3H), 7.62-7.40 (m, 5H) 
               
               
                 51 
                 □□□δ = 8.84-8.82 (m, 2H), 8.76-8.74 (m, 1H), 8.67-8.65 (dd, 2H), 
                 675.24 
                 675.23 
               
               
                   
                 8.54-8.53 (m, 1H), 8.51-8.48 (m, 2H), 8.26-8.12 (m, 7H), 8.08-8.05 
               
               
                   
                 (m, 2H), 8.01-7.95 (m, 4H), 7.84-7.80 (m, 1H), 7.69-7.64 (m, 2H), 
               
               
                   
                 7.62-7.58 (m, 3H), 7.47-7.39 (m, 2H) 
               
               
                 54 
                 □□□δ = 8.83-8.81 (m, 1H), 8.58 (d, 1H), 8.51-8.50 (m, 1H), 8.48- 
                 598.19 
                 598.20 
               
               
                   
                 8.47 (dd, 1H), 8.39-8.36 (m, 1H), 8.32 (s, 1H), 8.29-8.27 (m, 1H), 
               
               
                   
                 8.11-8.06 (m, 2H), 8.02-7.95 (m, 3H), 7.90-7.86 (m, 1H), 7.84-7.77 
               
               
                   
                 (m, 4H), 7.70-7.66 (m, 2H), 7.63-7.39 (m, 6H), 7.30-7.25 (m, 1H) 
               
               
                 60 
                 □□□δ = 8.83-8.81 (dd, 1H), 8.51-8.50 (m, 1H), 8.32-8.31 (m, 1H), 
                 670.22 
                 670.21 
               
               
                   
                 8.11-8.01 (m, 3H), 7.97-7.95 (m, 2H), 7.84-7.80 (m, 1H), 7.68-7.40 
               
               
                   
                 (m, 20H), 7.09-7.05 (m, 2H) 
               
               
                 64 
                 □□□δ = 8.78-8.76 (m, 1H), 8.54-8.53 (m, 1H), 8.47-8.46 (m, 1H), 
                 660.21 
                 660.22 
               
               
                   
                 8.36-8.35 (m, 1H), 8.32-8.31 (m, 1H), 8.21-8.19 (m, 2H), 8.08-8.06 
               
               
                   
                 (m, 3H), 8.01-7.91 (m, 5H), 7.84-7.80 (m, 2H), 7.71-7.69 (dd, 1H), 
               
               
                   
                 7.63-7.58 (m, 2H), 7.53-7.40 (m, 6H), 7.34-7.24 (m, 2H) 
               
               
                 66 
                 □□□δ = 8.82-8.80 (m, 1H), 8.52-8.51 (m, 1H), 8.43-8.42 (m, 1H), 
                 674.25 
                 674.24 
               
               
                   
                 8.35-8.32 (m, 4H), 8.28-8.26 (dd, 2H), 8.14-8.13 (m, 1H), 8.08-8.05 
               
               
                   
                 (m, 1H), 8.00-7.94 (m, 5H), 7.85-7.80 (m, 1H), 7.66-7.40 (m, 11H), 
               
               
                   
                 7.31-7.26 (m, 2H) 
               
               
                 72 
                 □□□δ = 8.81-8.79 (m, 1H), 8.50-8.49 (m, 1H), 8.42-8.41 (m, 1H), 
                 570.19 
                 570.20 
               
               
                   
                 8.14(s, 1H), 8.08-8.06 (m, 1H), 8.00-7.95 (m, 2H), 7.91-7.80 (m, 
               
               
                   
                 6H), 7.74-7.40 (m, 2H), 7.66-7.58 (m, 2H), 7.54-7.49 (m, 2H), 7.47- 
               
               
                   
                 7.30 (m, 6H), 7.05-7.00 (m, 1H) 
               
               
                 84 
                 □□□δ = 8.82-8.80 (m, 1H), 8.51-8.50 (m, 1H), 8.47-8.46 (m, 1H), 
                 710.25 
                 710.24 
               
               
                   
                 8.43-8.42 (m, 1H), 8.41-8.40 (m, 1H), 8.14 (s, 1H), 8.08-8.06 (m, 
               
               
                   
                 1H), 8.00-7.96 (m, 4H), 7.92-7.81 (m, 4H), 7.71-7.69 (dd, 1H), 7.62- 
               
               
                   
                 7.58 (m, 2H), 7.52-7.35 (m, 8H), 7.34-7.26 (m, 4H) 
               
               
                 89 
                 □□□δ = 8.81-8.79 (m, 1H), 8.51-8.50 (m, 1H), 8.43-8.42 (m, 1H), 
                 720.22 
                 720.22 
               
               
                   
                 8.15-8.14 (m, 1H), 8.09-8.06 (m, 1H), 8.01-7.89 (m, 8H), 7.84-7.80 
               
               
                   
                 (m, 1H), 7.70-7.58 (m, 7H), 7.53-7.39 (m, 8H), 7.37-7.29 (m, 4H) 
               
               
                 96 
                 □□□δ = 8.81-8.79 (m, 1H), 8.52-8.51 (m, 1H), 8.43-8.42 (m, 1H), 
                 660.17 
                 660.18 
               
               
                   
                 8.36-8.35 (m, 1H), 8.15-8.14 (m, 1H), 8.08-8.02 (m, 3H), 8.00-7.81 
               
               
                   
                 (m, 8H), 7.68-7.65 (m, 1H), 7.63-7.56 (m, 3H), 7.54-7.50 (m, 2H), 
               
               
                   
                 7.47-7.35(m, 4H), 7.33-7.29 (m, 2H) 
               
               
                   
               
            
           
         
       
     
     Example 1 
     An ITO glass substrate (a product of Corning Co., Ltd) with an ITO layer having a resistance and thickness of 15 Ω/cm 2 /1,200 Å thereon was cut to a size of 50 mm×50 mm×0.7 mm, and then, sonicated by using isopropyl alcohol and pure water each for 5 minutes, and cleaned by the exposure to ultraviolet rays for 30 minutes, and then ozone, and the ITO glass substrate was mounted on a vacuum deposition apparatus. 
     2-TNATA was deposited on the ITO glass substrate to form a hole injection layer having a thickness of 600 Å, NPB was deposited on the hole injection layer to form a hole transport layer having a thickness of 300 Å, and then ADN (host) and DPAVBi (dopant) were co-deposited at a weight ratio of 98:2 on the hole transport layer to form an emission layer having a thickness of 300 Å. 
     Thereafter, Compound 1 was deposited on the emission layer to form an electron transport layer having a thickness of 300 Å, LiF was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å, and Al was deposited on the electron injection layer to form a cathode having a thickness of 3,000 Å, thereby completing the manufacture of an organic light-emitting device. 
     
       
         
         
             
             
         
       
     
     Example 2 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound 2 was used instead of Compound 1. 
     Example 3 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming the electron transport layer, Compound 9 was used instead of Compound 1. 
     Example 4 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming the electron transport layer, Compound 25 was used instead of Compound 1. 
     Example 5 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming the electron transport layer, Compound 38 was used instead of Compound 1. 
     Example 6 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound 60 was used instead of Compound 1. 
     Example 7 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound 72 was used instead of Compound 1. 
     Example 8 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound 84 was used instead of Compound 1. 
     Example 9 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound 96 was used instead of Compound 1. 
     Comparative Example 1 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound 200 was used instead of Compound 1. 
     
       
         
         
             
             
         
       
     
     Comparative Example 2 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound A was used instead of Compound 1. 
     
       
         
         
             
             
         
       
     
     Comparative Example 3 
     An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an electron transport layer, Compound B was used instead of Compound 1. 
     
       
         
         
             
             
         
       
     
     Evaluation Example 1 
     The driving voltage, current density, brightness, efficiency, and half-lifespan of the organic light-emitting devices manufactured according to Examples 1 to 9 and Comparative Examples 1 to 3 were measured by using Kethley SMU 236 and a brightness photometer PR650, and results thereof are shown in Table 2. The half-lifespan is a period of time that is taken until the brightness of the organic light-emitting device was 50% of initial brightness. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Driving 
                 Current 
                   
                   
                   
                 Half lifespan 
               
               
                   
                 Electron 
                 voltage 
                 Density 
                 Brightness 
                 Efficiency 
                 Emission 
                 (hr 
               
               
                   
                 transport layer 
                 (V) 
                 (mA/cm 2 ) 
                 (cd/m 2 ) 
                 (cd/A) 
                 color 
                 @100 mA/cm 2 ) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 Compound 1 
                 4.37 
                 50 
                 4,175 
                 8.35 
                 Blue 
                 602 
               
               
                 Example 2 
                 Compound 2 
                 4.56 
                 50 
                 3,875 
                 7.75 
                 Blue 
                 583 
               
               
                 Example 3 
                 Compound 9 
                 4.46 
                 50 
                 4,005 
                 8.01 
                 Blue 
                 576 
               
               
                 Example 4 
                 Compound 25 
                 4.11 
                 50 
                 4,290 
                 8.58 
                 Blue 
                 552 
               
               
                 Example 5 
                 Compound 38 
                 4.05 
                 50 
                 4,130 
                 8.26 
                 Blue 
                 635 
               
               
                 Example 6 
                 Compound 60 
                 4.61 
                 50 
                 3,815 
                 7.63 
                 Blue 
                 625 
               
               
                 Example 7 
                 Compound 72 
                 4.00 
                 50 
                 4,000 
                 8.00 
                 Blue 
                 617 
               
               
                 Example 8 
                 Compound 84 
                 4.28 
                 50 
                 3,980 
                 7.96 
                 Blue 
                 605 
               
               
                 Example 9 
                 Compound 96 
                 4.15 
                 50 
                 4,080 
                 8.16 
                 Blue 
                 592 
               
               
                 Comparative 
                 Compound 
                 5.12 
                 50 
                 3,290 
                 6.58 
                 Blue 
                 317 
               
               
                 Example 1 
                 200 
               
               
                 Comparative 
                 Compound A 
                 5.34 
                 50 
                 3,170 
                 6.34 
                 Blue 
                 298 
               
               
                 Example 2 
               
               
                 Comparative 
                 Compound B 
                 5.54 
                 50 
                 3,380 
                 6.76 
                 Blue 
                 323 
               
               
                 Example 3 
               
               
                   
               
            
           
         
       
     
     From Table 2, it may be seen that the organic light-emitting devices manufactured according to Examples 1 to 9 exhibited improved driving voltage, brightness, efficiency, and half-lifespan, compared with the organic light-emitting devices manufactured according to Comparative Examples 1 to 3. 
     An organic light-emitting device including the compound according to an embodiment may have a low driving voltage, high efficiency, high brightness, and long lifespan. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.