Patent Publication Number: US-2022235081-A1

Title: Organometallic compound, organic light-emitting device including the same, and electronic apparatus including the organic light-emitting device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Korean Patent Application No. 10-2021-0003569, filed on Jan. 11, 2021, in the Korean Intellectual Property Office, and all benefits accruing therefrom under 35 U.S.C. § 119, the content of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     One or more embodiments relate to an organometallic compound, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device. 
     2. Description of the Related Art 
     Organic light-emitting devices (OLEDs) are self-emissive devices and have improved characteristics in terms of viewing angles, response time, luminance, driving voltage, and response speed. OLEDs often can achieve these features and produce full-color images. 
     In an example, an organic light-emitting device includes an anode, a cathode, and an organic layer located between the anode and the cathode, wherein the organic layer includes an emission layer. A hole transport region may be located between the anode and the emission layer, and an electron transport region may be located between the emission layer and the cathode. Holes provided from the anode may move toward the emission layer through the hole transport region, and electrons provided from the cathode may move toward the emission layer through the electron transport region. The holes and the electrons may recombine in the emission layer to produce excitons. These excitons transition from an excited state to a ground state to thereby generate light, for example visible light. 
     SUMMARY 
     One or more embodiments provide an organometallic compound, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device. 
     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 of the disclosure. 
     According to an aspect, provided is an organometallic compound represented by Formula 1. 
       M 1 (L 1 ) n1 (L 2 ) n2   Formula 1
 
     In Formula 1, 
     M 1  is a transition metal, 
     L 1  is a ligand represented by Formula 1-1, 
     L 2  is a ligand represented by Formula 1-2, 
     n1 and n2 are each 1 or 2, 
     
       
         
         
             
             
         
       
     
     wherein, in Formulae 1-1 and 1-2, 
     X 11  is N or C(R 12 ), X 12  is N or C(R 13 ), X 13  is N or C(R 14 ), X 14  is N or C(R 15 ), provided that at least one of X 11  to X 14  is N, 
     L 11  is a single bond, a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , 
     a11 is an integer from 1 to 3, 
     Y 1 , Y 2 , and Y 11  are each independently C or N, 
     T 1  is a single bond, a double bond, O, S, C(R 3 )(R 4 ), Si(R 3 )(R 4 ), * 1 ═C(R 3 )—* 2 , or * 1 —C(R 3 )═* 2 , * 1  and * 2  each indicate a binding site to ring CY 1  and ring CY 2  in Formula 1, 
     ring CY 1 , ring CY 2 , and ring CY 11  are each independently a C 5 -C 30  carbocyclic group or a C 1 -C 30  heterocyclic group, 
     R 1  to R 4  and R 11  to R 16  are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF 5 , 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 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 1 -C 60  alkylthio 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 7 -C 60  alkyl aryl group, a substituted or unsubstituted C 7 -C 60  aryl alkyl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted C 2 -C 60  alkyl heteroaryl group, a substituted or unsubstituted C 2 -C 60  heteroaryl alkyl group, a substituted or unsubstituted C 1 -C 60  heteroaryloxy group, a substituted or unsubstituted C 1 -C 60  heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q 1 )(Q 2 ), —Si(Q 3 )(Q 4 )(Q 5 ), —Ge(Q 3 )(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), —P(═O)(Q 8 )(Q 9 ), or —P(Q 8 )(Q 9 ), 
     b1, b2, and b11 are each independently an integer from 0 to 20, 
     two or more of a plurality of R 1 (s) are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , 
     two or more of a plurality of R 2 (s) are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , 
     two or more of a plurality of R 11 (s) are optionally be linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , and 
     two or more of R 12  to R 15  are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , 
     R 10a  is as defined in connection with R 1  to R 4  and R 11  to R 16 , 
     * and *′ each indicate a binding site to M 1  in Formula 1, and 
     a substituent of the substituted C 1 -C 60  alkyl group, the substituted C 2 -C 60  alkenyl group, the substituted C 2 -C 60  alkynyl group, the substituted C 1 -C 60  alkoxy group, the substituted C 3 -C 10  cycloalkyl group, the substituted C 1 -C 10  heterocycloalkyl group, the substituted C 3 -C 10  cycloalkenyl group, the substituted C 1 -C 10  heterocycloalkenyl group, the substituted C 6 -C 60  aryl group, the substituted C 6 -C 60  aryloxy group, the substituted C 6 -C 60  arylthio group, the substituted C 1 -C 60  heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is: 
     deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro 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, or a C 1 -C 60  alkylthio group, 
     a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, or a C 1 -C 60  alkylthio group, each substituted with deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro 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 C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 11 )(Q 12 ), —Si(Q 13 )(Q 14 )(Q 15 ), —Ge(Q 13 )(Q 14 )(Q 15 ), —B(Q 16 )(Q 17 ), —P(═O)(Q 18 )(Q 19 ), —P(Q 18 )(Q 19 ), or a combination 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, or 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, or a monovalent non-aromatic condensed heteropolycyclic group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro 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 1 -C 60  alkylthio 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 7 -C 60  alky aryl group, a C 7 -C 60  aryl alkyl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  alkyl heteroaryl group, a C 2 -C 60  heteroaryl alkyl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 21 )(Q 22 ), —Si(Q 23 )(Q 24 )(Q 25 ), —Ge(Q 23 )(Q 24 )(Q 25 ), —B(Q 26 )(Q 27 ), —P(═O)(Q 28 )(Q 29 ), —P(Q 28 )(Q 29 ), or a combination thereof, 
     —N(Q 31 )(Q 32 ), —Si(Q 33 )(Q 34 )(Q 35 ), —Ge(Q 33 )(Q 34 )(Q 35 ), —B(Q 36 )(Q 37 ), —P(═O)(Q 38 )(Q 39 ), or —P(Q 38 )(Q 39 ), or 
     a combination thereof, 
     wherein Q 1  to Q 9 , Q 11  to Q 19 , Q 21  to Q 29 , and Q 31  to Q 39  are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro 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 that is unsubstituted or substituted with deuterium, a C 1 -C 30  alkyl group, a C 6 -C 60  aryl group, or a combination thereof, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 1 -C 60  alkylthio 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 that is unsubstituted or substituted with deuterium, a C 1 -C 60  alkyl group, a C 6 -C 60  aryl group, or a combination thereof, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group. 
     According to another aspect, provided is an organic light-emitting device including a first electrode, a second electrode, and an organic layer including an emission layer between the first electrode and the second electrode, wherein the organic layer includes at least one of the organometallic compounds. 
     The organometallic compound is included in the emission layer of the organic layer, and the organometallic compound included in the emission layer may act as a dopant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawing, in which 
       The FIGURE is a schematic cross-sectional view of an organic light-emitting device according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout the specification. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the FIGURE, to explain aspects. 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. 
     The terminology used herein is for the purpose of describing one or more exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “or” means “and/or.” It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. 
     It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the present embodiments. 
     Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims. 
     It will be understood that when an element is referred to as being “on” another element, it can be directly in contact with the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this general inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value. 
     An organometallic compound according to aspects of one or more embodiments is represented by Formula 1: 
       M 1 (L 1 ) n1 (L 2 ) n2   Formula 1
 
     M 1  in Formula 1 is a transition metal. 
     For example, M 1  may be a Period 1 transition metal, a Period 2 transition metal, or a Period 3 transition metal. 
     In one or more embodiments, M 1  may be iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), thulium (Tm), or rhodium (Rh). 
     In one or more embodiments, M 1  may be Ir, Pt, Os, or Rh. 
     For example, M 1  may be Ir. 
     In Formula 1, L 1  is a ligand represented by Formula 1-1, and L 2  is a ligand represented by Formula 1-2: 
     
       
         
         
             
             
         
       
     
     Formulae 1-1 and 1-2 are as defined in the present specification. 
     n1 in Formula 1 indicates the number of L 1 (s), and is 1 or 2. When n1 is 2 or more, two or more of L 1 (s) are identical to or different from each other. 
     n2 in Formula 1 indicates the number of L 2 (s), and is 1 or 2. When n2 is 2 or more, two or more of L 2 (s) are identical to or different from each other. 
     In Formula 1, the sum of n1 and n2 may be 3. 
     For example, n1 may be 1, and n2 may be 2. 
     L 1  and L 2  in Formula 1 may be different from each other. 
     In one or more embodiments, in Formula 1, M 1  may be Ir or Os, and the sum of n1 and n2 may be 3 or 4; or M 1  may be Pt, and the sum of n1 and n2 may be 2. 
     In one or more embodiments, in Formula 1, M 1  may be Ir, n1 and n2 may each independently be 1 or 2, and the sum of n1 and n2 may be 3. 
     In Formula 1-2, X 11  may be N or C(R 12 ), X 12  may be N or C(R 13 ), X 13  may be N or C(R 14 ), X 14  may be N or C(R 15 ), provided that at least one of X 11  to X 14  may be N. 
     In one or more embodiments, 
     a) X 11  may be N, X 12  may be C(R 13 ), X 13  may be C(R 14 ), and X 14  may be C(R 15 ); 
     b) X 11  may be C(R 12 ), X 12  may be N, X 13  may be C(R 14 ), and X 14  may be C(R 15 ); 
     c) X 11  may be C(R 12 ), X 12  may be C(R 13 ), X 13  may be N, and X 14  may be C(R 15 ); 
     d) X 11  may be C(R 12 ), X 12  may be C(R 13 ), X 13  may be C(R 14 ), and X 14  may be N; 
     e) X 11  may be N, X 12  may be C(R 13 ), X 13  may be N, and X 14  may be C(R 15 ); 
     f) X 11  may be N, X 12  may be N, X 13  may be C(R 14 ), and X 14  may be C(R 15 ); 
     g) X 11  may be N, X 12  may be C(R 13 ), X 13  may be C(R 14 ), and X 14  may be N; 
     h) X 11  may be N, X 12  may be N, X 13  may be N, and X 14  may be C(R 15 ); 
     i) X 11  may be N, X 12  may be N, X 13  may be C(R 14 ), and X 14  may be N; 
     j) X 11  may be N, X 12  may be C(R 13 ), X 13  may be N, and X 14  may be N; 
     k) X 11  may be C(R 12 ), X 12  may be N, X 13  may be N, and X 14  may be N; or 
     l) X 11  may be N, X 12  may be N, X 13  may be N, and X 14  may be N. 
     In Formula 1-2, L 11  is a single bond, a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a . 
     In one or more embodiments, L 11  may be: 
     a single bond; or 
     a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a furan group, a thiophene group, a silole group, an indene group, a fluorene group, an indole group, a carbazole group, a benzofuran group, a dibenzofuran group, a benzothiophene group, a dibenzothiophene group, a benzosilole group, a dibenzosilole group, an azafluorene group, an azacarbazole group, an azadibenzofuran group, an azadibenzothiophene group, an azadibenzosilole group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, or a benzothiadiazole group, each unsubstituted or substituted with at least one R 10a . 
     For example, L 11  may be: 
     a single bond; or 
     a benzene group, a naphthalene group, a pyridine group, a dibenzofuran group, a dibenzothiophene group, or a carbazole group, each unsubstituted or substituted with at least one R 10a . 
     a11 in Formula 1-2 indicates the number of L 11 (s), and is an integer from 1 to 3. When a11 is 2 or more, two or more of L 11 (s) are identical to or different from each other. 
     In one or more embodiments, a11 may be 1. 
     Y 1 , Y 2 , and Y 11  in Formula 1-2 are each independently C or N. 
     In one or more embodiments, Y 1  may be N, and Y 2  and Y 11  may each be C. 
     T 1  in Formula 1-1 is a single bond, a double bond, O, S, C(R 3 )(R 4 ), Si(R 3 )(R 4 ), * 1 ═C(R 3 )—* 2 , or * 1 —C(R 3 )═* 2 , wherein * 1  and * 2  each indicate a binding site to ring CY 1  and ring CY 2  in Formula 1. For example, T 1  may be a single bond. 
     ring CY 1 , ring CY 2 , and ring CY 11  in Formulae 1-1 and 1-2 are each independently a C 5 -C 30  carbocyclic group or a C 1 -C 30  heterocyclic group. 
     For example, ring CY 1 , ring CY 2 , and ring CY 11  may each independently be i) a first ring, ii) a second ring, iii) a condensed ring wherein two or more first rings are condensed with each other, iv) a condensed ring wherein two or more second rings are condensed with each other, or v) a condensed ring wherein one or more first rings and one or more second rings are condensed with each other, 
     the first ring may be a cyclopentane group, a cyclopentadiene group, a furan group, a thiophene group, a pyrrole group, a silole group, an indene group, a benzofuran group, a benzothiophene group, an indole group, a benzosilole group, an oxazole group, an isoxazole group, an oxadiazole group, an isoxadiazole group, an oxatriazole group, an isoxatriazole group, a thiazole group, an isothiazole group, a thiadiazole group, an isothiadiazole group, a thiatriazole group, an isothiatriazole group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an azasilole group, a diazasilole group, or a triazasilole group, and 
     the second ring may be an adamantane group, a norbornane group, a norbornene group, a bicyclo[1.1.1]pentane group, a bicyclo[2.1.1]hexane group, a bicyclo[2.2.1]heptane group, a bicyclo[2.2.2]octane group, a cyclohexane group, a cyclohexene group, a benzene group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, or a triazine group. 
     In one or more embodiments, ring CY 1 , ring CY 2 , and ring CY 11  may each independently be i) a first ring or ii) a second ring. 
     In one or more embodiments, ring CY 1 , ring CY 2 , and ring CY 11  may each independently be a condensed ring wherein two or more rings are condensed with each other. 
     In one or more embodiments, ring CY 1 , ring CY 2 , and ring CY 11  may each independently be iii) a condensed ring wherein two or more first rings are condensed with each other, iv) a condensed ring wherein two or more second rings are condensed with each other, or v) a condensed ring wherein one or more first rings and one or more second rings are condensed with each other. 
     In one or more embodiments, ring CY 1 , ring CY 2 , and ring CY 11  may each independently be a cyclopentane group, a cyclohexane group, a cycloheptane group, a cyclopentene group, a cyclohexene group, a cycloheptene group, an adamantane group, a norbornane group, a norbornene group, a bicyclo[1.1.1]pentane group, a bicyclo[2.1.1]hexane group, a bicyclo[2.2.1]heptane group, a bicyclo[2.2.2]octane group, a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a 1,2,3,4-tetrahydronaphthalene group, a pyrrole group, a borole group, a phosphole group, a cyclopentadiene group, a silole group, a germole group, a thiophene group, a selenophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a benzoisoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrazole group, an imidazole group, a triazole group, an azaborole group, an azaphosphole group, an azacyclopentadiene group, an azasilole group, an azagermole group, an azaselenophene group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group. 
     In one or more embodiments, ring CY 1  and ring CY 2  in Formula 1-1 may each independently be a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a benzoisoquinoline group, a quinoxaline group, a quinazoline group, or a phenanthroline group. 
     In one or more embodiments, ring CY 11  in Formula 1-2 may be a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a fluorene group, a dibenzoborole group, a dibenzophosphole group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a benzoisoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrazole group, an imidazole group, a triazole group, an azaborole group, an azaphosphole group, an azacyclopentadiene group, an azasilole group, an azagermole group, an azaselenophene group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group. 
     For example, ring CY 11  in Formula 1-2 may be a benzene group, a dibenzofuran group, an azadibenzofuran group, or a benzothiazole group. 
     R 1  to R 4  and R 11  to R 16  in Formulae 1-1 and 1-2 are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF 5 , 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 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 1 -C 60  alkylthio 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 7 -C 60  alkyl aryl group, a substituted or unsubstituted C 7 -C 60  aryl alkyl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted C 2 -C 60  alkyl heteroaryl group, a substituted or unsubstituted C 2 -C 60  heteroaryl alkyl group, a substituted or unsubstituted C 1 -C 60  heteroaryloxy group, a substituted or unsubstituted C 1 -C 60  heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q 1 )(Q 2 ), —Si(Q 3 )(Q 4 )(Q 5 ), —Ge(Q 3 )(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), —P(═O)(Q 8 )(Q 9 ), or —P(Q 8 )(Q 9 ). Q 1  to Q 9  are as defined in the present specification. 
     In one or more embodiments, R 1  to R 4  and R 11  to R 16  may each independently be: 
     hydrogen, 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, —SF 5 , a C 1 -C 20  alkyl group, or a C 1 -C 20  alkoxy group; 
     a C 1 -C 20  alkyl group or a C 1 -C 20  alkoxy group, each substituted with deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , 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 10  alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a (C 1 -C 20  alkyl)cyclopentyl group, a (C 1 -C 20  alkyl)cyclohexyl group, a (C 1 -C 20  alkyl)cycloheptyl group, a (C 1 -C 20  alkyl)cyclooctyl group, a (C 1 -C 20  alkyl)adamantanyl group, a (C 1 -C 20  alkyl)norbornanyl group, a (C 1 -C 20  alkyl)norbornenyl group, a (C 1 -C 20  alkyl)cyclopentenyl group, a (C 1 -C 20  alkyl)cyclohexenyl group, a (C 1 -C 20  alkyl)cycloheptenyl group, a (C 1 -C 20  alkyl)bicyclo[1.1.1]pentyl group, a (C 1 -C 20  alkyl)bicyclo[2.1.1]hexyl group, a (C 1 -C 20  alkyl)bicyclo[2.2.1]heptyl group, a (C 1 -C 20  alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or a combination thereof; 
     a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl 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 quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzoisothiazolyl 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, an imidazopyridinyl group, an imidazopyrimidinyl group, an azacarbazolyl group, an azadibenzofuranyl group, or an azadibenzothiophenyl group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , 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 20  alkyl group, a deuterium-containing C 2 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a (C 1 -C 20  alkyl)cyclopentyl group, a (C 1 -C 20  alkyl)cyclohexyl group, a (C 1 -C 20  alkyl)cycloheptyl group, a (C 1 -C 20  alkyl)cyclooctyl group, a (C 1 -C 20  alkyl)adamantanyl group, a (C 1 -C 20  alkyl)norbornanyl group, a (C 1 -C 20  alkyl)norbornenyl group, a (C 1 -C 20  alkyl)cyclopentenyl group, a (C 1 -C 20  alkyl)cyclohexenyl group, a (C 1 -C 20  alkyl)cycloheptenyl group, a (C 1 -C 20  alkyl)bicyclo[1.1.1]pentyl group, a (C 1 -C 20  alkyl)bicyclo[2.1.1]hexyl group, a (C 1 -C 20  alkyl)bicyclo[2.2.1]heptyl group, a (C 1 -C 20  alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C 1 -C 20  alkyl)phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl 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 quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzoisothiazolyl 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, an imidazopyridinyl group, an imidazopyrimidinyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, or a combination thereof; or 
     —N(Q 1 )(Q 2 ), —Si(Q 3 )(Q 4 )(Q 5 ), —Ge(Q 3 )(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), —P(═O)(Q 8 )(Q 9 ), or —P(Q 8 )(Q 9 ), 
     wherein Q 1  to Q 5  may each independently be: 
     —CH 3 , —CD 3 , —CD 2 H, —CDH 2 , —CH 2 CH 3 , —CH 2 CD 3 , —CH 2 CD 2 H, —CH 2 CDH 2 , —CHDCH 3 , —CHDCD 2 H, —CHDCDH 2 , —CHDCD 3 , —CD 2 CD 3 , —CD 2 CD 2 H, or —CD 2 CDH 2 ; or 
     an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, a neopentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a sec-isopentyl group, a phenyl group, a biphenyl group, or a naphthyl group, each unsubstituted or substituted with deuterium, a C 1 -C 10  alkyl group, a phenyl group, or a combination thereof. 
     In one or more embodiments, R 1  to R 4  and R 11  to R 16  may each independently be hydrogen, deuterium, —F, a cyano group, a nitro group, —SF 5 , —CH 3 , —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a group represented by one of Formulae 9-1 to 9-66, a group represented by one of Formulae 9-1 to 9-66 wherein at least one hydrogen is substituted with deuterium, a group represented by one of Formulae 10-1 to 10-118, a group represented by one of Formulae 10-1 to 10-118 wherein at least one hydrogen is substituted with deuterium, a group represented by one of Formulae 10-201 to 10-342, or a group represented by one of Formulae 10-201 to 10-342 wherein at least one hydrogen is substituted with deuterium: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     wherein, in Formulae 9-1 to 9-66, 10-1 to 10-118, and 10-201 to 10-342, * indicates a binding site to a neighboring atom, Ph is a phenyl group, and TMS is a trimethylsilyl group. 
     The “group represented by one of Formulae 9-1 to 9-66 wherein at least one hydrogen is substituted with deuterium” may be a group represented by one of Formulae 9-501 to 9-514 and 9-601 to 9-638: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     The “group represented by one of Formulae 10-1 to 10-118 wherein at least one hydrogen is substituted with deuterium” may be a group represented by one of Formulae 10-501 to 10-546: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In one or more embodiments, R 11  to R 15  in Formula 1-2 may each independently be hydrogen, deuterium, —F, a cyano group, a substituted or unsubstituted C 1 -C 60  alkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkyl group, —Si(Q 3 )(Q 4 )(Q 5 ), or —Ge(Q 3 )(Q 4 )(Q 5 ), and 
     R 16  may be 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  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted C 1 -C 60  heteroaryloxy group, a substituted or unsubstituted C 1 -C 60  heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. 
     b1, b2, and b11 in Formulae 1-1 and 1-2 indicate the numbers of R 1 , R 2 , and R 11 , respectively, are each independently an integer from 0 to 20. When b1 is 2 or more, two or more of R 1 (s) are identical to or different from each other, and when b2 is 2 or more, two or more of R 2 (s) are identical to or different from each other, and when b11 is 2 or more, two or more of R 11 (s) are identical to or different from each other. For example, b1, b2, and b11 may each independently be an integer from 0 to 10. 
     In Formulae 1-1 and 1-2, 
     two or more of a plurality of R 1 (s) are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , 
     two or more of a plurality of R 2 (s) are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , 
     two or more of a plurality of R 11 (s) are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a , and 
     two or more of R 12  to R 15  are optionally linked to each other to form a C 5 -C 30  carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30  heterocyclic group unsubstituted or substituted with at least one R 10a . 
     In one or more embodiments, R 11  and R 16  may not be linked to each other. 
     In one or more embodiments, a group represented by 
     
       
         
         
             
             
         
       
     
     in Formula 1-1 may be a group represented by one of Formulae CY1-1 to CY1-35, 
     and/or 
     a group represented by 
     
       
         
         
             
             
         
       
     
     in Formula 1-1 may be a group represented by one of Formulae CY2-1 to CY2-35: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In Formulae CY1-1 to CY1-35 and CY2-1 to CY2-35, 
     X 41  may be O, S, N(Z 11 ), C(Z 11 )(Z 12 ), or Si(Z 11 )(Z 12 ), 
     X 42  may be O, S, N(Z 21 ), C(Z 21 )(Z 22 ), or Si(Z 21 )(Z 22 ), 
     Y 1  and Y 2  are as defined in the present specification, 
     Z 1 , Z 2 , Z 11  to Z 18 , and Z 21  to Z 28  are as defined in connection with R 1  to R 4  and R 11  to R 16  in the present specification, 
     d2 may each independently be an integer from 0 to 2, 
     d3 may each independently be an integer from 0 to 3, 
     d4 may each independently be an integer from 0 to 4, 
     d5 may each independently be an integer from 0 to 5, 
     d6 may each independently be an integer from 0 to 6, and 
     in Formulae CY1-1 to CY1-35 and CY2-1 to CY2-35, * and *′ each indicate a binding site to M 1  in Formula 1, and *″ indicates a binding site to a neighboring atom in Formula 1-1 or T 1  in Formula 1-1. 
     In one or more embodiments, L 1  in Formula 1 may be a ligand represented by Formula 1-1(1): 
     
       
         
         
             
             
         
       
     
     In Formula 1-1(1), 
     Y 1 , Y 2 , ring CY 2 , R 2 , and b2 are as defined in the present specification, 
     R 21  to R 24  are as defined in connection with R 1  to R 4  and R 11  to R 16  in the present specification, and 
     * and *′ each indicate a binding site to M 1  in Formula 1. 
     For example, R 21  to R 24  in Formula 1-1(1) may each independently be: hydrogen; F; —Si(Q 3 )(Q 4 )(Q 5 ); —Ge(Q 3 )(Q 4 )(Q 5 ); or a C 1 -C 60  alkyl group substituted with at least one deuterium. 
     For example, R 22  and R 23  in Formula 1-1(1) may each be: hydrogen; —Si(Q 3 )(Q 4 )(Q 5 ); —Ge(Q 3 )(Q 4 )(Q 5 ); a C 1 -C 60  alkyl group; a C 6 -C 60  aryl group; or a C 1 -C 60  alkyl group substituted with at least one deuterium, a C 1 -C 60  alkyl group, or a C 6 -C 60  aryl group, and R 21  and R 24  may each be hydrogen. 
     In one or more embodiments, L 1  in Formula 1 may be a ligand represented by Formula 1-1(2): 
     
       
         
         
             
             
         
       
     
     In Formula 1-1(2), 
     Y 1 , ring CY 1 , R 1 , and b1 are as defined in the specification, 
     R 25  to R 26  are as defined in connection with R 1  to R 4  and R 11  to R 16  in the present specification, and 
     * and *′ each indicate a binding site to M 1  in Formula 1. 
     For example, R 25  to R 26  in Formula 1-1(2) may each independently be: hydrogen; —F; —Si(Q 3 )(Q 4 )(Q 5 ); —Ge(Q 3 )(Q 4 )(Q 5 ); a C 1 -C 60  alkyl group; a C 6 -C 60  aryl group; or a C 1 -C 60  alkyl group substituted with at least one deuterium. 
     For example, R 26  in Formula 1-1(2) may be hydrogen or a C 1 -C 60  alkyl group substituted with at least one deuterium, a C 1 -C 60  alkyl group, or a C 6 -C 60  aryl group, and R 25 , R 27 , and R 26  may each be hydrogen. 
     In one or more embodiments, L 2  in Formula 1 may be a ligand represented by one of Formulae 1-2(1) to 1-2(4): 
     
       
         
         
             
             
         
       
     
     In Formulae 1-2(1) to 1-2(4), 
     X 11  to X 14 , L 11 , a11, and R 16  are as defined in the present specification, 
     X 21  may be N or C(R 35 ), X 22  may be N or C(R 36 ), X 23  may be N or C(R 37 ), and X 24  may be N or C(R 38 ), 
     X 31  may be O, S, N(R 39 ), or C(R 39 )(R 40 ), 
     R 31  to R 40  are as defined in connection with R 1  to R 4  and R 11  to R 16  in the present specification, and 
     * and *′ each indicate a binding site to M 1  in Formula 1. 
     For example, X 31  in Formulae 1-2(2) and 1-2(4) may be O or S. 
     For example, in Formula 1-2(4), 
     X 21  may be N, X 22  may be C(R 36 ), X 23  may be C(R 37 ), and X 24  may be C(R 38 ), or 
     X 21  may be C(R 35 ), X 22  may be C(R 36 ), X 23  may be C(R 37 ), and X 24  may be C(R 38 ). 
     R 10a  is as defined in connection with R 1  in the present specification. 
     * and *′ in Formulae 1-1 and 1-2 each indicate a binding site to M in Formula 1. 
     The terms “an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluoren-9-one group, and an azadibenzothiophene 5,5-dioxide group” respectively refer to heterocyclic groups having the same backbones as “an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluoren-9-one group, and a dibenzothiophene 5,5-dioxide group,” wherein, in each group, at least one carbon selected from ring-forming carbons is substituted with nitrogen. 
     In one or more embodiments, the organometallic compound represented by Formula 1 may be one of Compounds 1 to 2024: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     In the organometallic compound represented by Formula 1, L 1  is a ligand represented by Formula 1-1, and n1 indicates the number of L 1 (s) and is 1 or 2. That is, the organometallic compound is a ligand linked to metal M 1 , and necessarily includes at least one ligand represented by Formula 1-1. 
     The ligand represented by Formula 1-1 may have a bidentate ligand structure wherein two cyclic groups are linked to each other, and thus, due to the organometallic complex stabilization effect of the bidentate cyclic groups, a long lifespan and improved full width at half maximum (FWHM) in an organic light-emitting device may be achieved. 
     In the organometallic compound represented by Formula 1, L 2  is a ligand represented by Formula 1-2, and n2 indicates the number of L 2 (s) and is 1 or 2. That is, the organometallic compound is a ligand linked to metal M 1 , and necessarily includes at least one ligand represented by Formula 1-2. 
     The ligand represented by Formula 1-2 may have a structure wherein a 6-membered ring including at least one N is condensed to an imidazole ring, and thus, due to the highest occupied molecular orbital (HOMO) energy level stabilization effect of the nitrogen atoms, a relatively low driving voltage may be obtained. 
     Furthermore, the ligand represented by Formula 1-2 may optionally have a structure wherein an imidazole condensed cyclic ligand and ring CY 11  are not linked to each other, and thus, the physical separation of a HOMO energy level and a lowest unoccupied molecular orbital (LUMO) energy level may be clarified, thereby obtaining a high photoluminescence quantum yield (PLQY) and efficiency. 
     Synthesis methods of the organometallic compound represented by Formula 1 may be recognizable by one of ordinary skill in the art by referring to Synthesis Examples provided herein. 
     Accordingly, the organometallic compound represented by Formula 1 is suitable for use as a material for an organic layer of an organic light-emitting device, for example, as a dopant in an emission layer of the organic layer. Thus, one or more embodiments of another aspect provide an organic light-emitting device including: a first electrode; a second electrode; and an organic layer located between the first electrode and the second electrode, wherein the organic layer includes an emission layer, and wherein the organic layer includes at least one organometallic compound represented by Formula 1. 
     The organic light-emitting device may have, due to the inclusion of an organic layer including at least one of the organometallic compounds represented by Formula 1, a low driving voltage, high efficiency, high power, high quantum efficiency, a long lifespan, an improved degree of horizontal orientation, and excellent color purity. 
     The organometallic compound of Formula 1 may be located between a pair of electrodes of an organic light-emitting device. For example, the organometallic compound represented by Formula 1 may be included in the emission layer. In this regard, the organometallic compound may act as a dopant, and the emission layer may further include a host (that is, an amount of the organometallic compound represented by Formula 1 is less than an amount of the host). The emission layer may emit red light or green light. 
     The expression “(an organic layer) includes at least one of the organometallic compounds” as used herein may include a case wherein “(an organic layer) includes one organometallic compound represented by Formula 1” and a case wherein “(an organic layer) includes two or more different organometallic compounds represented by Formula 1”. 
     For example, the organic layer may include, as the organometallic compound, only Compound 1. In this embodiment, Compound 1 may be included in the emission layer of the organic light-emitting device. In one or more embodiments, the organic layer may include, as the organometallic compound, Compound 1 and Compound 2. In this regard, Compound 1 and Compound 2 may be in an identical layer (for example, Compound 1 and Compound 2 may both be in an emission layer). 
     The first electrode may be an anode, which is a hole injection electrode, and the second electrode may be a cathode, which is an electron injection electrode; or the first electrode may be a cathode, which is an electron injection electrode, and the second electrode may be an anode, which is a hole injection electrode. 
     In one or more embodiments, in the organic light-emitting device, the first electrode is an anode, and the second electrode is a cathode, and the organic layer may further include a hole transport region located between the first electrode and the emission layer, and an electron transport region located between the emission layer and the second electrode, wherein the hole transport region may include a hole injection layer, a hole transport layer, an electron blocking layer, a buffer layer, or a combination thereof, and the electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof. 
     The term “organic layer” as used herein may refer to either a single layer or a plurality of layers between the first electrode and the second electrode of the organic light-emitting device. The “organic layer” may include, in addition to an organic compound, an organometallic complex including a metal. 
     The FIGURE is a schematic cross-sectional view of an organic light-emitting device  10  according to one or more embodiments of the present disclosure. Hereinafter, the structure of an organic light-emitting device according to one or more embodiments of the present disclosure and a method of manufacturing an organic light-emitting device according to one or more embodiments of the present disclosure will be described in connection with the FIGURE. The organic light-emitting device  10  includes a first electrode  11 , an organic layer  15 , and a second electrode  19 , which are sequentially stacked. 
     A substrate may be additionally located under the first electrode  11  or above the second electrode  19 . For use as the substrate, any substrate that is used in organic light-emitting devices available in the art may be used, and the substrate may be a glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance. 
     In one or more embodiments, the first electrode  11  may be formed by depositing or sputtering a material for forming the first electrode  11  on the substrate. The first electrode  11  may be an anode. The material for forming the first electrode  11  may include materials with a high work function to facilitate hole injection. The first electrode  11  may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for forming the first electrode  11  may be indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO 2 ), or zinc oxide (ZnO). In one or more embodiments, the material for forming the first electrode  11  may be metal, such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag). 
     The first electrode  11  may have a single-layered structure or a multi-layered structure including two or more layers. For example, the first electrode  11  may have a three-layered structure of ITO/Ag/ITO, but the structure of the first electrode  11  is not limited thereto. 
     The organic layer  15  may be located on the first electrode  11 . 
     The organic layer  15  may include a hole transport region, an emission layer, and an electron transport region. 
     The hole transport region may be located between the first electrode  11  and the emission layer. 
     The hole transport region may include a hole injection layer, a hole transport layer, an electron blocking layer, a buffer layer, or a combination thereof. 
     The hole transport region may include only either a hole injection layer or a hole transport layer. In one or more embodiments, the hole transport region may have a hole injection layer/hole transport layer structure or a hole injection layer/hole transport layer/electron blocking layer structure, wherein, for each structure, each layer is sequentially stacked in this stated order in a direction extending from the first electrode  11  towards the second electrode  19 . 
     When the hole transport region includes a hole injection layer, the hole injection layer may be formed on the first electrode  11  by using one or more suitable methods, for example, vacuum deposition, spin coating, casting, and/or Langmuir-Blodgett (LB) deposition. 
     When a hole injection layer is formed by vacuum deposition, the deposition conditions may vary according to a material that is used to form the hole injection layer, and the structure and thermal characteristics of the hole injection layer. For example, the deposition conditions may include a deposition temperature of about 100° C. to about 500° C., a vacuum pressure of about 10 −8  torr to about 10 −3  torr, and a deposition rate of about 0.01 angstrom per second (Å/sec) to about 100 Å/sec. However, the deposition conditions are not limited thereto. 
     When the hole injection layer is formed using spin coating, coating conditions may vary according to the material used to form the hole injection layer, and the structure and thermal properties of the hole injection layer. For example, a coating speed may be from about 2,000 revolutions per minute (rpm) to about 5,000 rpm, and a temperature at which a heat treatment is performed to remove a solvent after coating may be from about 80° C. to about 200° C. However, the coating conditions are not limited thereto. 
     The conditions for forming the hole transport layer and the electron blocking layer may be similar to the conditions described herein for forming the hole injection layer. 
     The hole transport region may include 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDATA), 4,4′,4″-tris{N-(2-naphthyl)-N-phenylamino}-triphenylamine (2-TNATA), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), β-NPB, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine (TPD), spiro-TPD, spiro-NPB, methylated NPB, 4,4′-cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), 4,4′-bis[N,N′-(3-tolyl)amino]-3,3′-dimethylbiphenyl (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 sulfonic acid (PANI/CSA), polyaniline/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201 below, a compound represented by Formula 202 below, or a combination thereof: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Ar 101  and Ar 102  in Formula 201 may each independently be a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an acenaphthylene group, a fluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, or a pentacenylene group, each unsubstituted or substituted with 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 1 -C 60  alkylthio group, a C 3 -C 10  cycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 7 -C 60  alky aryl group, a C 7 -C 60  aryl alkyl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  alkyl heteroaryl group, a C 2 -C 60  heteroaryl alkyl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, or a combination thereof. 
     xa and xb in Formula 201 may each independently be an integer from 0 to 5, or 0, 1, or 2. For example, xa may be 1, and xb may be 0. 
     R 101  to R 108 , R 111  to R 119 , and R 121  to R 124  in Formulae 201 and 202 may each independently be: 
     hydrogen, 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 10  alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or the like) or a C 1 -C 10  alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, or the like); 
     a C 1 -C 10  alkyl group or a C 1 -C 10  alkoxy group, each substituted with 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, or a combination thereof; or 
     a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group or a pyrenyl group, each unsubstituted or substituted with 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 10  alkyl group, a C 1 -C 10  alkoxy group, or a combination thereof. 
     R 109  in Formula 201 may be a phenyl group, a naphthyl group, an anthracenyl group, or a pyridinyl group, each unsubstituted or substituted with 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 20 alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, a pyridinyl group, or a combination thereof. 
     According to one or more embodiments, the compound represented by Formula 201 may be represented by Formula 201A, but embodiments of the present disclosure are not limited thereto: 
     
       
         
         
             
             
         
       
     
     R 101 , R 111 , R 112 , and R 109  in Formula 201A may be understood by referring to the description provided herein. 
     For example, the compound represented by Formula 201, and the compound represented by Formula 202 may include compounds HT1 to HT20, but are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     A thickness of the hole transport region may be in a range of about 100 Å to about 10,000 Å, for example, about 100 Å to about 1,000 Å. When the hole transport region includes a hole injection layer, a hole transport layer, or a combination thereof, a thickness of the hole injection layer may be in a range of about 100 Å to about 10,000 Å, for example, about 100 Å to about 1,000 Å, and a thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, for example, about 100 Å to about 1,500 Å. When the thicknesses of the hole transport region, the hole injection layer and the hole transport layer are within 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, for example, a p-dopant. The p-dopant may be one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound, but embodiments of the present disclosure are not limited thereto. Examples of the p-dopant are: a quinone derivative, such as tetracyanoquinodimethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinodimethane (F4-TCNQ); a metal oxide, such as a tungsten oxide or a molybdenum oxide; a cyano group-containing compound, such as Compound HT-D1, or a combination thereof, but are not limited thereto. 
     
       
         
         
             
             
         
       
     
     The hole transport region may include a buffer layer. 
     Without wishing to be bound to theory, the buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, and thus, the efficiency of a formed organic light-emitting device may be improved. 
     Meanwhile, when the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be selected from materials for the hole transport region as defined herein, materials for a host as defined herein, or a combination thereof. However, the material for the electron blocking layer is not limited thereto. For example, when the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be mCP, as described herein. 
     An emission layer may be formed on the hole transport region, for example, by vacuum deposition, spin coating, casting, LB deposition, or the like. When the emission layer is formed by vacuum deposition or spin coating, the deposition or coating conditions may be similar to those applied in forming the hole injection layer although the deposition or coating conditions may vary according to a material that is used to form the hole transport layer. 
     The emission layer may include a host and a dopant, and the dopant may include the organometallic compound represented by Formula 1. 
     The host may include 1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi), 3-tert-butyl-9,10-di(naphth-2-yl)anthracene (TBADN), 9,10-di(naphthalene-2-yl)anthracene (ADN, also referred to as “DNA”), 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), 4,4′-bis(9-carbazolyl)-2,2′-dimethyl-biphenyl (CDBP), TCP, mCP, Compound H50, Compound H51, or a combination thereof: 
     
       
         
         
             
             
         
       
     
     When the organic light-emitting device is a full-color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and/or a blue emission layer. In one or more embodiments, due to a stacked structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit white light. 
     When the emission layer includes a host and a dopant, an amount of the dopant may be in a range of about 0.01 parts by weight to about 15 parts by weight based on 100 parts by weight of the host, but embodiments of the present disclosure are not limited thereto. 
     The dopant may include an organometallic compound represented by Formula 1. For example, the dopant may be a green phosphorescent dopant. 
     A thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å, for example, about 200 Å to about 600 Å. When the thickness of the emission layer is within these ranges, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage. 
     Then, an electron transport region may be located on the emission layer. 
     The electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof. 
     For example, the electron transport region may have a hole blocking layer/electron transport layer/electron injection layer structure or an electron transport layer/electron injection layer structure, and the structure of the electron transport region is not limited thereto. The electron transport layer may have a single-layered structure or a multi-layered structure including two or more different materials. 
     Conditions for forming the hole blocking layer, the electron transport layer, and the electron injection layer, which constitute the electron transport region, may be understood by referring to the conditions for forming the hole injection layer. 
     When the electron transport region includes a hole blocking layer, the hole blocking layer may include, for example, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), bis(2-methyl-8-quinolinolato-N1,08)-(1,1′-biphenyl-4-olato)aluminum (BPhen), bis(2-methyl-8-quinolinolato-N1,08)-(1,1′-biphenyl-4-olato)aluminum (Balq), or a combination thereof, but embodiments of the present disclosure are not limited thereto. 
     
       
         
         
             
             
         
       
     
     A thickness of the hole blocking layer may be in a range of about 20 Å to about 1,000 Å, for example, about 30 Å to about 300 Å. When the thickness of the hole blocking layer is within these ranges, excellent hole blocking characteristics may be obtained without a substantial increase in driving voltage. 
     The electron transport layer may include BCP, BPhen, tris(8-hydroxyquinolinato)aluminum (Alq 3 ), Balq, 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), or a combination thereof. 
     
       
         
         
             
             
         
       
     
     In one or more embodiments, the electron transport layer may include at least one of Compounds ET1 to ET25 and a combination thereof, but are not limited thereto: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     A thickness of the electron transport layer may be in the range of about 100 Å to about 1,000 Å, for example, 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 transporting characteristics without a substantial increase in driving voltage. 
     The electron transport layer may include a metal-containing material in addition to the material as described above. 
     The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (LiQ) or ET-D2: 
     
       
         
         
             
             
         
       
     
     The electron transport region may include an electron injection layer that promotes the flow of electrons from the second electrode  19  thereinto. 
     The electron injection layer may include LiF, NaCl, CsF, Li 2 O, BaO, or a combination thereof. 
     A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, for example, 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  19  may be located on the organic layer  15 . The second electrode  19  may be a cathode. A material for forming the second electrode  19  may be metal, an alloy, an electrically conductive compound, or a combination thereof, which have a relatively low work function. For example, lithium (Li), magnesium (Mg), aluminum (AI), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag) may be used as the material for forming the second electrode  19 . In one or more embodiments, to manufacture a top-emission type light-emitting device, a transmissive electrode formed using ITO or IZO may be used as the second electrode  19 . 
     Hereinbefore, the organic light-emitting device has been described with reference to the FIGURE, but embodiments of the present disclosure are not limited thereto. 
     According to one or more embodiments of another aspect, the organic light-emitting device may be included in an electronic apparatus. Thus, an electronic apparatus including the organic light-emitting device is provided. The electronic apparatus may include, for example, a display, lighting, a sensor, and the like. 
     Another aspect provides a diagnostic composition including at least one organometallic compound represented by Formula 1. 
     The organometallic compound represented by Formula 1 provides high luminescent efficiency. Accordingly, a diagnostic composition including the organometallic compound may have high diagnostic efficiency. 
     The diagnostic composition may be used in various applications including a diagnosis kit, a diagnosis reagent, a biosensor, and a biomarker. 
     The term “C 1 -C 60  alkyl group” as used herein refers to a linear or branched saturated aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms. The term “C 1 -C 60  alkylene group” as used herein refers to a divalent group having the same structure as the C 1 -C 60  alkyl group. 
     Examples of the C 1 -C 60  alkyl group, the C 1 -C 20  alkyl group, and/or the C 1 -C 10  alkyl group as used herein may include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, a neopentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a sec-isopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group, an isodecyl group, a sec-decyl group, or a tert-decyl group, each unsubstituted or substituted with a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, a neopentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a sec-isopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, or a combination thereof. 
     The term “C 1 -C 60  alkoxy group” as used herein refers to a monovalent group represented by —OA 101  (wherein A 101  is the C 1 -C 60  alkyl group), and examples thereof include a methoxy group, an ethoxy group, and an isopropyloxy group. Other examples of the C 1 -C 60  alkoxy group, the C 1 -C 20  alkoxy group, or the C 1 -C 10  alkoxy group as used herein may include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a pentoxy group. 
     The term “C 1 -C 60  alkylthio group” as used herein is represented by —SA 104  (wherein A 104  is the C 1 -C 60  alkyl group). 
     The term “C 2 -C 60  alkenyl group” as used herein refers to a hydrocarbon group formed by substituting at least one carbon-carbon double bond in the middle or at the terminus of the C 2 -C 60  alkyl group, and examples thereof include an ethenyl group, a propenyl group, and a butenyl group. The term “C 2 -C 60  alkenylene group” as used herein refers to a divalent group having the same structure as the C 2 -C 60  alkenyl group. 
     The term “C 2 -C 60  alkynyl group” as used herein refers to a hydrocarbon group formed by substituting at least one carbon-carbon triple bond in the middle or at the terminus of the C 2 -C 60  alkyl group, and examples thereof include an ethynyl group and a propynyl group. The term “C 2 -C 60  alkynylene group” as used herein refers to a divalent group having the same structure as the C 2 -C 60  alkynyl group. 
     The term “C 3 -C 10  cycloalkyl group” as used herein refers to a monovalent saturated hydrocarbon monocyclic group having 3 to 10 carbon atoms. The term “C 3 -C 10  cycloalkylene group” as used herein refers to a divalent group having the same structure as the C 3 -C 10  cycloalkyl group. Examples of the C 3 -C 10  cycloalkyl group as used herein may include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, and a bicyclo[2.2.2]octyl group. 
     The term “C 1 -C 10  heterocycloalkyl group” as used herein refers to a monovalent saturated monocyclic group having at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom and 1 to 10 carbon atoms, and non-limiting examples thereof include a tetrahydrofuranyl group and a tetrahydrothiophenyl group. The term “C 1 -C 10  heterocycloalkylene group” as used herein refers to a divalent group having the same structure as the C 1 -C 10  heterocycloalkyl group. 
     The term “C 3 -C 10  cycloalkenyl group” as used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one carbon-carbon double bond in the ring thereof and no aromaticity, and non-limiting examples thereof include a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The term “C 3 -C 10  cycloalkenylene group” as used herein refers to a divalent group having the same structure as the C 3 -C 10  cycloalkenyl group. 
     The term “C 1 -C 10  heterocycloalkenyl group” as used herein refers to a monovalent monocyclic group that has at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom, 1 to 10 carbon atoms, and at least one double bond in its ring. Examples of the C 1 -C 10  heterocycloalkenyl group are a 2,3-dihydrofuranyl group and a 2,3-dihydrothiophenyl group. The term “C 1 -C 10  heterocycloalkenylene group” as used herein refers to a divalent group having the same structure as the C 1 -C 10  heterocycloalkenyl group. 
     The term “C 6 -C 60  aryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms, and the term “C 6 -C 60  arylene group” as used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Examples of the C 6 -C 60  aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C 6 -C 60  aryl group and the C 6 -C 60  arylene group each include two or more rings, the rings may be fused to each other. 
     The term “C 7 -C 60  alkyl aryl group” used herein refers to a C 6 -C 60  aryl group substituted with at least one C 1 -C 60  alkyl group. The term “C 7 -C 60  aryl alkyl group” as used herein refers to a C 1 -C 60  alkyl group substituted with at least one C 6 -C 60  aryl group. 
     The term “C 1 -C 60  heteroaryl group” as used herein refers to a monovalent group having at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom and a cyclic aromatic system having 1 to 60 carbon atoms, and the term “C 1 -C 60  heteroarylene group” as used herein refers to a divalent group having at least one heteroatom from N, O, P, Si, and S as a ring-forming atom and a carbocyclic aromatic system having 1 to 60 carbon atoms. Examples of the C 1 -C 60  heteroaryl group include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group. When the C 6 -C 60  heteroaryl group and the C 6 -C 60  heteroarylene group each include two or more rings, the rings may be fused to each other. 
     The term “C 2 -C 60  alkyl heteroaryl group” as used herein refers to a C 1 -C 60  heteroaryl group substituted with at least one C 1 -C 60  alkyl group. The term “C 7 -C 60  heteroaryl alkyl group” as used herein refers to a C 1 -C 60  alkyl group substituted with at least one C 1 -C 60  heteroaryl group. 
     The term “C 6 -C 60  aryloxy group” as used herein indicates —OA 102 (wherein A 102  is the C 6 -C 60  aryl group), and the term “C 6 -C 60  arylthio group” as used herein indicates —SA 103  (wherein A 103  is the C 6 -C 60  aryl group). 
     The term “C 1 -C 60  heteroaryloxy group” as used herein indicates —OA 112  (wherein A 112  is the C 1 -C 60  heteroaryl group), and the term “C 1 -C 60  heteroarylthio group” as used herein indicates —SA 113  (wherein A 113  is the C 1 -C 60  heteroaryl group). 
     The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) having two or more rings condensed to each other, only carbon atoms as ring-forming atoms, and no aromaticity in its entire molecular structure. Examples of the monovalent non-aromatic condensed polycyclic group include a fluorenyl group. The term “divalent non-aromatic condensed polycyclic group” as used herein refers to a divalent group having the same structure as a monovalent non-aromatic condensed polycyclic group. 
     The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group (for example, having 2 to 60 carbon atoms) having two or more rings condensed to each other, a heteroatom selected from N, O, P, Si, and S, other than carbon atoms, as a ring-forming atom, and no aromaticity in its entire molecular structure. Examples of the monovalent non-aromatic condensed heteropolycyclic group include a carbazolyl group. The term “divalent non-aromatic heterocondensed polycyclic group” as used herein refers to a divalent group having the same structure as a monovalent non-aromatic heterocondensed polycyclic group. 
     The term “C 5 -C 30  carbocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, 5 to 30 carbon atoms only. The C 5 -C 30  carbocyclic group may be a monocyclic group or a polycyclic group. 
     The term “C 1 -C 30  heterocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, at least one heteroatom selected from N, O, Si, P, and S other than 1 to 30 carbon atoms. The C 1 -C 30  heterocyclic group may be a monocyclic group or a polycyclic group. 
     A substituent of the substituted C 5 -C 30  carbocyclic group, the substituted C 2 -C 30  heterocyclic group, the substituted C 1 -C 60  alkyl group, the substituted C 2 -C 60  alkenyl group, the substituted C 2 -C 60  alkynyl group, the substituted C 1 -C 60  alkoxy group, the substituted C 1 -C 60  alkylthio group, the substituted C 3 -C 10  cycloalkyl group, the substituted C 1 -C 10  heterocycloalkyl group, the substituted C 3 -C 10  cycloalkenyl group, the substituted C 1 -C 10  heterocycloalkenyl group, the substituted C 6 -C 60  aryl group, the substituted C 7 -C 60  alkyl aryl group, the substituted C 7 -C 60  aryl alkyl group, the substituted C 6 -C 60  aryloxy group, the substituted C 6 -C 60  arylthio group, the substituted C 1 -C 60  heteroaryl group, the substituted C 2 -C 60  alkyl heteroaryl group, the substituted C 2 -C 60  heteroaryl alkyl group, the substituted C 1 -C 60  heteroaryloxy group, the substituted C 1 -C 60  heteroarylthio group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be: 
     deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro 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, or a C 1 -C 60  alkylthio group; 
     a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, or a C 1 -C 60  alkylthio group, each substituted with deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro 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 7 -C 60  alkyl aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a C 2 -C 60  alkyl heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 11 )(Q 12 ), —Si(Q 13 )(Q 14 )(Q 15 ), —B(Q 16 )(Q 17 ), —P(═O)(Q 18 )(Q 19 ), —P(Q 18 )(Q 19 ), or a combination 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 7 -C 60  alkyl aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  alkyl heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or 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 7 -C 60  alkyl aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a C 2 -C 60  alkyl heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group, each substituted with deuterium, —F, —Cl, —Br, —I, —CD 3 , —CD 2 H, —CDH 2 , —CF 3 , —CF 2 H, —CFH 2 , a hydroxyl group, a cyano group, a nitro 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 1 -C 60  alkylthio 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 7 -C 60  alkyl aryl group, a C 7 -C 60  aryl alkyl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 2 -C 60  alkyl heteroaryl group, a C 2 -C 60  heteroaryl alkyl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —N(Q 21 )(Q 22 ), —Si(Q 23 )(Q 24 )(Q 25 ), —B(Q 26 )(Q 27 ), —P(═O)(Q 28 )(Q 29 ), —P(Q 28 )(Q 29 ), or a combination thereof; 
     —N(Q 31 )(Q 32 ), —Si(Q 33 )(Q 34 )(Q 35 ), —B(Q 36 )(Q 37 ), —P(═O)(Q 38 )(Q 39 ), or —P(Q 38 )(Q 39 ); or 
     a combination thereof. 
     Q 1  to Q 9 , Q 11  to Q 19 , Q 21  to Q 29 , and Q 31  to Q 39  as used herein may each independently be: hydrogen; deuterium; —F; —Cl; —Br; —I; a hydroxyl group; a cyano group; a nitro 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 that is unsubstituted or substituted with deuterium, a C 1 -C 60  alkyl group, a C 6 -C 60  aryl group, or a combination thereof; a C 2 -C 60  alkenyl group; a C 2 -C 60  alkynyl group; a C 1 -C 60  alkoxy group; a C 1 -C 30  alkylthio 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 that is unsubstituted or substituted with deuterium, a C 1 -C 60  alkyl group, a C 6 -C 60  aryl group, or a combination thereof; 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 C 1 -C 60  heteroaryloxy group; a C 1 -C 60  heteroarylthio group; or a monovalent non-aromatic condensed heteropolycyclic group. 
     The “C 5 -C 30  carbocyclic group (unsubstituted or substituted with at least one R 10a )” and the “C 1 -C 30  heterocyclic group (unsubstituted or substituted with at least one R 10a )” as used herein may be, for example, a cyclopentane group, a cyclohexane group, a cycloheptane group, a cyclopentene group, a cyclohexene group, a cycloheptene group, an adamantane group, a norbornane group, a norbornene group, a bicyclo[1.1.1]pentane group, a bicyclo[2.1.1]hexane group, a bicyclo[2.2.1]heptane group, a bicyclo[2.2.2]octane group, a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a 1,2,3,4-tetrahydronaphthalene group, a pyrrole group, a borole group, a phosphole group, a cyclopentadiene group, a silole group, a germole group, a thiophene group, a selenophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a benzoquinoline group, a benzoisoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrazole group, an imidazole group, a triazole group, an azaborole group, an azaphosphole group, an azacyclopentadiene group, an azasilole group, an azagermole group, an azaselenophene group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group, each (unsubstituted or substituted with at least one R 10a ). 
     Hereinafter, a compound and an organic light-emitting device according to one or more exemplary embodiments are described in further detail with reference to Synthesis Examples and Examples. However, the present disclosure is not limited thereto. The wording “B was used instead of A” used in describing Synthesis Examples means that an amount of A used was identical to an amount of B used, in terms of a molar equivalent. 
     EXAMPLES 
     Synthesis Example 1: Synthesis of Compound 2023 
     Synthesis of Compound C4 
     
       
         
         
             
             
         
       
     
     2-bromo-5-(trimethylsilyl)pyridine (10 grams (g), 43.44 millimoles (mmol)), phenylboronic acid (5.83 g, 47.79 mmol), tetrakis(triphenylphosphine)Pd(0) (Pd(PPh 3 ) 4 ) (2.51 g, 2.17 mmol), and K 2 CO 3  (18.01 g, 130.33 mmol) were mixed with 90 mL of tetrahydrofuran (THF) and 30 mL of deionized (DI) water, and then, the mixture was stirred for 18 hour while heating at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was purified by performing column chromatography using ethyl acetate (EA) and hexanes in a volume ratio of 1:4 to obtain 7.23 g (73%) of Compound C4. 
     Synthesis of Compound B4 
     
       
         
         
             
             
         
       
     
     C4 (5.0 g, 22.04 mmol) and iridium chloride (3.70 g, 10.49 mmol) were mixed with 90 mL of 2-ethoxyethanol and 30 mL of DI water, the mixture was stirred for 24 hours while heating at reflux, and then, the temperature was lowered to room temperature. The resulting solid was separated by filtration, washed sufficiently with DI water, methanol, and hexane, in this stated order, and then dried in a vacuum oven to obtain 6.53 g (46%) of Compound B4. 
     Synthesis of Compound A4 
     
       
         
         
             
             
         
       
     
     Compound B4 (5.00 g, 3.67 mmol) was mixed with 90 mL of methylene chloride (MC), and then, silver triflate (AgOTf) (2.03 g, 7.90 mmol) dissolved in 30 mL of methanol was added thereto. Thereafter, the mixture was stirred for 18 hours at room temperature while light was blocked with aluminum foil to process the reaction, and then filtered through Celite to remove the resulting solid. The filtrate was subjected to reduced pressure to obtain a solid (Compound A4), which was used in the next reaction without an additional purification process. 
     Synthesis of Compound L4 
     
       
         
         
             
             
         
       
     
     2-bromo-3-(3,5-diisopropyl-[1,1′-biphenyl]-4-yl)-4-methyl-3H-imidazo[4,5-c]pyridine (10 g, 22.30 mmol), dibenzo[b,d]furan-4-ylboronic acid (5.20 g, 24.53 mmol), Pd(PPh 3 ) 4 (1.29 g, 1.12 mmol), and K 2 CO 3  (9.25 g, 66.90 mmol) were mixed with 90 mL of THE and 30 mL of DI water, and then, the mixture was stirred for 18 hours while heating at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was purified by performing column chromatography using a mixture of ethyl acetate and hexanes in a 1:2 ratio by volume to obtain 8.29 g (69%) of Compound L4. 
     Synthesis of Compound 2023 
     
       
         
         
             
             
         
       
     
     Compound A4 (5.00 g, 5.83 mmol) and Compound L4 (3.43 g, 6.41 mmol) were mixed with 50 mL of 2-ethoxyethanol and 50 mL of N,N-dimethylformamide, the mixture was stirred at a temperature of 120° C. for 48 hours while heating at reflux, and then the temperature was lowered. After a solvent was completely removed under a condition of reduced pressure, column chromatography was performed using ethyl acetate and hexanes in a ratio of 1:5 by volume to obtain 1.84 g (27%) of Compound 2023. The obtained compound was identified by Mass and HPLC analysis. 
     High resolution mass spectrometry (HRMS) using matrix assisted laser desorption ionization (MALDI): calcd for C 65 H 64 IrN 5 OSi 2 : m/z: 1179.4279. Found: 1179.4253. 
     Synthesis Example 2: Synthesis of Compound 843 
     Synthesis of Compound C5 
     
       
         
         
             
             
         
       
     
     2-bromo-4-isobutyl-5-(trimethylsilyl)pyridine (10 g, 34.93 mmol), phenylboronic acid (4.69 g, 38.42 mmol), Pd(PPh 3 ) 4  (2.02 g, 1.75 mmol), and K 2 CO 3  (14.48 g, 104.79 mmol) were mixed with 90 mL of THF and 30 mL of DI water, and then, the mixture was stirred for 18 hours at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was purified by performing column chromatography using ethyl acetate and hexanes in a ratio of 1:4 by volume to obtain 6.62 g (83%) of Compound C5. 
     Synthesis of Compound B5 
     
       
         
         
             
             
         
       
     
     C5 (4.98 g, 17.57 mmol) and iridium chloride (2.95 g, 8.37 mmol) were mixed with 90 mL of 2-ethoxyethanol and 30 mL of DI water, the mixture was stirred for 24 hours while heating at reflux, and then the temperature was lowered to room temperature. The resulting solid was separated by filtration, washed sufficiently with DI water, methanol, and hexane, in this stated order, and then dried in a vacuum oven to obtain 6.12 g (46%) of Compound B5. 
     Synthesis of Compound A5 
     
       
         
         
             
             
         
       
     
     Compound B5 (5.00 g, 3.15 mmol) was mixed with 90 mL of MC, and then, AgOTf (1.74 g, 6.78 mmol) dissolved in 30 mL of methanol was added thereto. Thereafter, the mixture was stirred for 18 hours at room temperature while light was blocked with aluminum foil to process the reaction, and then filtered through Celite to remove the resulting solid. The filtrate was subjected to reduced pressure to obtain a solid (Compound A5), which was used in the next reaction without an additional purification process. 
     Synthesis of Compound L5 
     
       
         
         
             
             
         
       
     
     2-bromo-1-(3,5-diisopropyl-[1,1′-biphenyl]-4-yl)-1H-imidazo[4,5-c]pyridine (5 g, 11.51 mmol), dibenzo[b,d]furan-4-ylboronic acid (2.68 g, 12.66 mmol), Pd(PPh 3 ) 4  (0.67 g, 1.58 mmol), and K2C03 (4.77 g, 34.53 mmol) were mixed with 90 mL of THF and 30 mL of DI water, and then the mixture was stirred for 18 hours while heating at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was subject to column chromatography three times using ethyl acetate and hexanes in a ratio of 1:2 by volume to obtain 2.75 g (46%) of Compound L5. 
     Synthesis of Compound 843 
     
       
         
         
             
             
         
       
     
     Compound A5 (5.00 g, 5.15 mmol) and Compound L5 (2.96 g, 5.67 mmol) were mixed with 50 mL of 2-ethoxyethanol and 50 mL of N,N-dimethylformamide, the mixture was stirred at a temperature of 120° C. for 48 hours while refluxing to process the reaction, and then, the temperature was lowered. After a solvent completely removed under a condition of reduced pressure, column chromatography was performed using ethyl acetate and hexanes in a ratio of 1:5 by volume to obtain 0.31 g (5%) of Compound 843. The obtained compound was identified by HRMS and HPLC analysis. The obtained compound may be quickly decomposed in a solution. 
     HRMS (MALDI) calcd for C 72 H78IrN 5 OSi 2 : m/z: 1277.8370. Found: 1277.8355. 
     Synthesis Example 3: Synthesis of Compound 2024 
     Synthesis of Compound C6 
     
       
         
         
             
             
         
       
     
     2-bromo-5-(trimethylsilyl)pyridine (10 g, 43.44 mmol), phenylboronic acid (5.83 g, 47.79 mmol), Pd(PPh 3 ) 4 (2.51 g, 2.17 mmol), and K 2 CO 3  (18.01 g, 130.33 mmol) were mixed with 90 mL of THE and 30 mL of DI water, and then, the mixture was stirred for 18 hour while heating at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was purified by performing column chromatography using ethyl acetate and hexanes in a ratio of 1:4 by volume to obtain 7.23 g (73%) of Compound C6. 
     Synthesis of Compound B6 
     
       
         
         
             
             
         
       
     
     C6 (5.0 g, 22.04 mmol) and iridium chloride (3.70 g, 10.49 mmol) were mixed with 90 mL of 2-ethoxyethanol and 30 mL of DI water, the mixture was stirred for 24 hours while heating at reflux, and then the temperature was lowered to room temperature. The resulting solid was separated by filtration, washed sufficiently with DI water, methanol, and hexane, in this stated order, and then dried in a vacuum oven to obtain 6.53 g (46%) of Compound B6. 
     Synthesis of Compound A6 
     
       
         
         
             
             
         
       
     
     Compound B6 (5.00 g, 3.67 mmol) was mixed with 90 mL of MC, and then AgOTf (2.03 g, 7.90 mmol) dissolved in 30 mL of methanol was added thereto. Thereafter, the mixture was stirred for 18 hours at room temperature while light was blocked with aluminum foil to process the reaction, and then filtered through Celite to remove the resulting solid. The filtrate was subjected to reduced pressure to obtain a solid (Compound A6), which was used in the next reaction without an additional purification process. 
     Synthesis of Compound L6 
     
       
         
         
             
             
         
       
     
     2-bromo-3-(3,5-diisopropyl-[1,1′-biphenyl]-4-yl)-4,6-dimethyl-3H-imidazo[4,5-c]pyridine (10 g, 22.30 mmol), dibenzo[b,d]furan-4-ylboronic acid (5.20 g, 24.53 mmol), Pd(PPh 3 ) 4  (1.29 g, 1.12 mmol), and K 2 CO 3  (9.25 g, 66.90 mmol) were mixed with 90 mL of THE and 30 mL of DI water, and then, the mixture was stirred for 18 hours while refluxing. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was purified by performing column chromatography using ethyl acetate and hexanes in a ratio of 1:2 by volume to obtain 8.29 g (69%) of Compound L6. 
     Synthesis of Compound 2024 
     
       
         
         
             
             
         
       
     
     Compound A6 (4.00 g, 4.66 mmol) and Compound L6 (2.82 g, 5.13 mmol) were mixed with 30 mL of 2-ethoxyethanol and 30 mL of N,N-dimethylformamide, the mixture was stirred at a temperature of 120° C. for 48 hours while refluxing to process the reaction, and then, the temperature was lowered. After a solvent completely removed under a condition of reduced pressure, column chromatography was performed using ethyl acetate and hexanes in a ratio of 1:5 by volume to obtain 1.99 g (36%) of Compound 2024. The obtained compound was identified by HRMS and HPLC analysis. 
     HRMS (MALDI) calcd for C 66 H 66 IrN 5 OSi 2 : m/z: 1193.4435. Found: 1193.4474. 
     Synthesis Example 4: Synthesis of Compound 891 
     Synthesis of Compound C7 
     
       
         
         
             
             
         
       
     
     2-bromo-4-isobutyl-5-(trimethylsilyl)pyridine (10 g, 34.93 mmol), phenylboronic acid (4.69 g, 38.42 mmol), Pd(PPh 3 ) 4 (2.02 g, 1.75 mmol), and K 2 CO 3  (14.48 g, 104.79 mmol) were mixed with 90 mL of THE and 30 mL of DI water, and then, the mixture was stirred for 18 hours while heating at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was purified by performing column chromatography using ethyl acetate and hexanes in a ratio of 1:4 by volume to obtain 6.62 g (83%) of Compound C7. 
     Synthesis of Compound B7 
     
       
         
         
             
             
         
       
     
     C7 (4.98 g, 17.57 mmol) and iridium chloride hydrate (2.95 g, 8.37 mmol) were mixed with 90 mL of 2-ethoxyethanol and 30 mL of DI water, the mixture was stirred for 24 hours while heating at reflux, and then the temperature was lowered to room temperature. The resulting solid was separated by filtration, washed sufficiently with DI water, methanol, and hexane, in this stated order, and then dried in a vacuum oven to obtain 6.12 g (46%) of Compound B7. 
     Synthesis of Compound A7 
     
       
         
         
             
             
         
       
     
     Compound B7 (5.00 g, 3.15 mmol) was mixed with 90 mL of MC, and then AgOTf (1.74 g, 6.78 mmol) dissolved in 30 mL of methanol was added thereto. Thereafter, the mixture was stirred for 18 hours at room temperature while light was blocked with aluminum foil to process the reaction, and then filtered through Celite to remove the resulting solid. The filtrate was subjected to reduced pressure to obtain a solid (Compound A7), which was used in the next reaction without an additional purification process. 
     Synthesis of Compound L7 
     
       
         
         
             
             
         
       
     
     2-bromo-1-(3,5-diisopropyl-[1,1′-biphenyl]-4-yl)-5-methyl-1H-imidazo[4,5-b]pyridine (5 g, 11.51 mmol), dibenzo[b,d]furan-4-ylboronic acid (2.68 g, 12.66 mmol), Pd(PPh 3 ) 4  (0.67 g, 1.58 mmol), and K 2 CO 3  (4.77 g, 34.53 mmol) were mixed with 90 mL of THF and 30 mL of DI water, and then, the mixture was stirred for 18 hours while heating at reflux. After the temperature was lowered to room temperature, an organic layer was extracted by using methylene chloride, and anhydrous magnesium sulfate (MgSO 4 ) was added thereto to remove water. Then, the residue obtained by depressurizing the filtrate obtained by filtration was subject to column chromatography three times using ethyl acetate and hexanes in a ratio of 1:2 by volume to obtain 1.50 g (25%) of Compound L7. 
     Synthesis of Compound 891 
     
       
         
         
             
             
         
       
     
     Compound A7 (3.00 g, 3.09 mmol) and Compound L7 (1.82 g, 3.40 mmol) were mixed with 20 mL of 2-ethoxyethanol and 20 mL of N,N-dimethylformamide, the mixture was stirred at a temperature of 120° C. for 48 hours while heating at reflux, and then the temperature was lowered. After a solvent was completely removed under a condition of reduced pressure, column chromatography was performed using ethyl acetate and hexanes in a ratio of 1:5 by volume to obtain 0.41 g (10%) of Compound 891. The obtained compound was identified by HRMS and HPLC analysis. The obtained compound may be quickly decomposed in a solution. 
     HRMS(MALDI) calcd for C 73 H 80 IrN 5 OSi 2 : m/z: 1291.8640. Found: 1291.8624. 
     Evaluation Example 1: Evaluation of Properties of Organometallic Compound 
     The highest occupied molecular orbital (HOMO) energy level, lowest unoccupied molecular orbital (LUMO) energy level, lowest excited singlet (S 1 ) energy level, and lowest excited triplet (T 1 ) energy level of selected organometallic compounds represented by Formula 1 were evaluated by density functional theory (DFT) using the Gaussian 09 program with the molecular structure optimization obtained by B3LYP-based, and results thereof are shown in Table 1. From Table 1, it was confirmed that the organometallic compound represented by Formula 1 has such electric characteristics that are suitable for use as a dopant in an emission of an electric device, for example, an organic light-emitting device. The energy levels are reported in electron volts (eV). 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Compound No. 
                 HOMO (eV) 
                 LUMO (eV) 
                 S 1  (eV) 
                 T 1  (eV) 
               
               
                   
               
             
            
               
                   1 
                 −4.829 
                 −1.289 
                 2.856 
                 2.575 
               
               
                  843 
                 −4.797 
                 −1.266 
                 2.822 
                 2.482 
               
               
                  891 
                 −4.677 
                 −1.310 
                 2.685 
                 2.407 
               
               
                 2021 
                 −4.833 
                 −1.583 
                 2.563 
                 2.369 
               
               
                 2022 
                 −4.651 
                 −1.427 
                 2.557 
                 2.305 
               
               
                 2023 
                 −4. 518 
                 −1.313 
                 2.840 
                 2.539 
               
               
                 2024 
                 −4.829 
                 −1.294 
                 2.836 
                 2.544 
               
               
                 A 
                 −4.610 
                 −0.988 
                 2.922 
                 2.620 
               
               
                 B 
                 −5.390 
                 −1.480 
                 3.145 
                 2.814 
               
               
                 C 
                 −4.759 
                 −2.079 
                 2.162 
                 1.225 
               
               
                 D 
                 −4.787 
                 −1.201 
                 2.869 
                 2.544 
               
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
            
           
         
       
     
     Example 1 
     As an anode, an ITO-patterned glass substrate was cut to a size of 50 millimeter (mm)×50 mm×0.5 mm, sonicated with isopropyl alcohol and deionize (DI) water, each for 5 minutes, and then cleaned by exposure to ultraviolet rays and ozone for 30 minutes. The resultant glass substrate was loaded onto a vacuum deposition apparatus. 
     Compounds HT3 and F6-TCNNQ were co-deposited by vacuum on the anode at the weight ratio of 98:2 to form a hole injection layer having a thickness of 100 Å, and Compound HT3 was then deposited by vacuum on the hole injection layer to form a hole transport layer having a thickness of 1,650 Å. 
     Subsequently, CBP (host) and Compound 2023 (dopant) were co-deposited at a weight ratio of 95:5 on the hole transport layer to form an emission layer having a thickness of 400 Å. 
     Then, Compounds ET3 and ET-D1 were co-deposited at a volume ratio of 50:50 on the emission layer to form an electron transport layer having a thickness of 350 Å, ET-D1 was deposited by vacuum on the electron transport layer to form an electron injection layer having a thickness of 10 Å, and then Al was deposited by vacuum on the electron injection layer to form a cathode having a thickness of 1,000 Å, thereby completing the manufacture of an organic light-emitting device. 
     
       
         
         
             
             
         
       
     
     Examples 2 and 3 and Comparative Examples 1 to 4 
     Organic light-emitting devices were manufactured in a similar manner as in Example 1, except that in forming an emission layer, for use as a dopant, corresponding compounds shown in Table 2 were used instead of Compound 2023. 
     Evaluation Example 2: Evaluation of Properties of Organic Light-Emitting Devices 
     The driving voltage (volts, V), maximum value of external quantum efficiency (Max EQE, %), maximum current efficiency (Max Cd.A, %), degree of horizontal orientation (%), maximum emission wavelength (nm), FWHM (nm), and lifespan (%) of each of the organic light-emitting devices manufactured according to Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated, and results thereof are shown in Table 2. As evaluation apparatuses, a current-voltage meter (Keithley 2400) and a luminance meter (Minolta Cs-1000A) were used. The driving voltage, maximum value of external quantum efficiency, and maximum current efficiency in Table 2 are each expressed as a relative value (%) compared to Example 1 (i.e., with Example 1 being 100%). 
     In calculating the degree of horizontal orientation, mCP and organometallic compounds were co-deposited at a weight ratio of 96:4 on a quartz substrate at a vacuum degree of 10 −7  torr to form a film having a thickness of 40 nm, and then a sealing glass substrate was attached onto the film to seal the film. 
     Photoluminescent (PL) emission intensity per degree with respect to the film was measured from −150° to +150° by using a Luxol-OLED/analyzer ( LOA -100 by CoCoLink Inc.), and then a degree of horizontal orientation with respect to Compound Pt-1 was calculated by using the fitting program of the analyzer. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                 Max 
                 Max 
                   
                   
                   
                   
               
               
                   
                   
                 Driving  
                 EQE 
                 Cd.A 
                 Degree of  
                 Maximum 
                   
                   
               
               
                   
                 Dopant in 
                 Voltage 
                 relative 
                 relative 
                 horizontal 
                 emission  
                   
                 Lifespan 
               
               
                   
                 emission 
                 (V) 
                 ratio 
                 ratio 
                 orientation 
                 wavelength 
                 FWHM 
                 (T 97 ) 
               
               
                   
                 layer 
                 (%) 
                 (%) 
                 (%) 
                 (%) 
                 (nm) 
                 (nm) 
                 (%) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 2023 
                 100% 
                 100%  
                 100%  
                 88% 
                 531 
                 62.5 
                 100%  
               
               
                 Example 2 
                 2024 
                 100% 
                 101%  
                 101%  
                 86% 
                 529 
                 61.5 
                 110%  
               
               
                 Example 3 
                 891 
                 104% 
                 95% 
                 95% 
                 86% 
                 535 
                 68.5 
                 75% 
               
               
                 Comparative 
                 A 
                 108% 
                 90% 
                 90% 
                 — 
                 509 
                 74.6 
                 60% 
               
               
                 Example 1 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Comparative 
                 B 
                 125% 
                 78% 
                 78% 
                 — 
                 490 
                 88.6 
                 80% 
               
               
                 Example 2 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Comparative 
                 C 
                 126% 
                 80% 
                 80% 
                 — 
                 590 
                 84.3 
                 75% 
               
               
                 Example 3 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Comparative 
                 D 
                 115% 
                 88% 
                 88% 
                 78% 
                 527 
                 76.3 
                 90% 
               
               
                 Example 4 
               
               
                   
               
            
           
         
       
     
     From Table 2, it is confirmed that the organic light-emitting devices of Examples 1 to 3 have improved characteristics in terms of driving voltage, external quantum efficiency, current efficiency, lifespan, and degree of horizontal orientation, compared to the organic light-emitting devices of Comparative Examples 1 to 4. 
     Because the organometallic compound has excellent electrical characteristics, an electronic device using the organometallic compound, for example, an organic light-emitting device using the organometallic compound, may have improved characteristics in terms of driving voltage, current density, efficiency, power, color purity, and/or lifespan. Accordingly, a high-quality organic light-emitting device and electronic apparatus including the same may be implemented by using the organometallic compound. 
     It should be understood that exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each exemplary embodiment should typically be considered as available for other similar features or aspects in other exemplary embodiments. While one or more exemplary embodiments have been described with reference to the FIGURE, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.