Organic light-emitting device and apparatus including the same

Abstract

An organic light-emitting device and an apparatus including the same are disclosed. The organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode. The organic layer includes an emission layer, the emission layer includes a first compound, a second compound, a third compound, and a fourth compound, the first compound is represented by Formula 1, the second compound is represented by Formula 2, the third compound is represented by Formula 3, the fourth compound is represented by any one of Formulae 4-1 to 4-3, each as respectively described in the detailed description.

What is claimed is: 
     
         1 . An organic light-emitting device comprising:
 a first electrode;   a second electrode facing the first electrode; and   an organic layer between the first electrode and the second electrode,   wherein the organic layer comprises an emission layer,   the emission layer comprises a first compound, a second compound, a third compound, and a fourth compound,   the first compound comprises a first carbazole group and a second carbazole group linked to the first carbazole group;   the second compound comprises a triazine group;   the third compound comprises a metal complex containing platinum (Pt) or iridium (Ir);   the fourth compound is represented by any one of Formulae 4-1 to 4-3; and   the first compound, the second compound, the third compound, and the fourth compound are different from each other:
   (D 41 ) n41 -(L 41 ) a41 -(A 41 ) m41    <Formula 4-1>
 
   (D 41 ) n41 -(L 41 ) a41 -(A 41 ) m41 -(L 42 ) a42 -(D 42 ) n42    <Formula 4-2>
 
   (A 41 ) m41 -(L 41 ) a41 -(D 41 ) n41 -(L 42 ) a42 -(A 42 ) m42    <Formula 4-3>
 
   wherein in Formulae 4-1 to 4-3,   A 41  and A 42  are each independently selected from:
 a π electron-depleted nitrogen-free cyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 21 )(Q 2 ), and —N(Q 1 )(Q 2 ); 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ); and 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one π electron-depleted nitrogen-free cyclic group that is substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 21 )(Q 22 )(Q 23 ), —Si(Q 21 )(Q 22 )(Q 23 ), —B(Q 21 )(Q 22 ), and —N(Q 21 )(Q 22 ), 
   m41 and m42 are each independently selected from 1, 2, and 3,   D 41  and D 42  are each independently selected from:
 —F, a cyano group, a π electron-depleted nitrogen-containing cyclic group, a C(═O)-containing group, a P(═O)-containing group, and a P(═S)-containing group; 
 a π electron-depleted nitrogen-containing cyclic group, a C(═O)-containing group, a P(═O)-containing group, and a P(═S)-containing group, each substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group, and a π electron-depleted nitrogen-free cyclic group; 
 a π electron-depleted nitrogen-containing cyclic group, a C(═O)-containing group, a P(═O)-containing group, and a P(═S)-containing group, each substituted with at least one selected from a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group and a π electron-depleted nitrogen-free cyclic group that are each independently substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group, and a π electron-depleted nitrogen-free cyclic group; 
 a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group, each substituted with at least one selected from —F, a cyano group, and a π electron-depleted nitrogen-containing cyclic group; 
 a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group, each substituted with at least one π electron-depleted nitrogen-containing cyclic group that is substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group, and a π electron-depleted nitrogen-free cyclic group; and 
 a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group, each substituted with at least one selected from a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group that are each independently substituted with at least one selected from —F, a cyano group, and a π electron-depleted nitrogen-containing cyclic group, 
   n41 and n42 are each independently selected from 1, 2, and 3,   L 41  and L 42  are each independently selected from:
 a π electron-depleted nitrogen-free cyclic group, —C(Q 1 )(Q 2 )-, —Si(Q 21 )(Q 2 )-, —B(Q 1 )-, and —N(Q 1 )-; and 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ), and 
   a41 and a42 are each independently selected from 0, 1, 2, and 3, and   wherein Q 1  to Q 3 , Q 21  to Q 23  and Q 31  to Q 33  are each independently selected from 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 C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a 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, a biphenyl group, and a terphenyl group.   
     
     
         2 . The organic light-emitting device of  claim 1 , wherein the first carbazole group is linked to a nitrogen atom (N) of the second carbazole group. 
     
     
         3 . The organic light-emitting device of  claim 1 , wherein the first carbazole group and the second carbazole group are directly linked. 
     
     
         4 . The organic light-emitting device of  claim 1 , wherein the first compound further comprises a dibenzothiophene group, a dibenzofuran group, a benzene group or a third carbazole group, linked to a nitrogen atom (N) of the first carbazole group. 
     
     
         5 . The organic light-emitting device of  claim 1 , wherein the first compound further comprises a first linking group, and
 the second carbazole group is linked to the first carbazole group through the first linking group.   
     
     
         6 . The organic light-emitting device of  claim 5 , wherein the first linking group comprises at least one benzene group. 
     
     
         7 . The organic light-emitting device of  claim 1 , wherein emission wavelength of the organic light-emitting device is about 450 nm to about 490 nm. 
     
     
         8 . The organic light-emitting device of  claim 1 , wherein the first compound is represented by one of Formulae 1-1 to 1-5: 
       
         
           
           
               
               
           
         
         wherein, in Formulae 1-1 to 1-5, 
         A 11  is the second carbazole group represented by Formula 8-1, 
       
       
         
           
           
               
               
           
         
         R11 to R19 are each independently selected from:
 hydrogen, deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), and —N(Q 1 )(Q 2 ); 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ); and 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one π electron-depleted nitrogen-free cyclic group that is substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 21 )(Q 22 )(Q 23 ), —Si(Q 21 )(Q 22 )(Q 23 ), —B(Q 21 )(Q 22 ), and —N(Q 21 )(Q 22 ), 
 
         L 11  is selected from:
 a π electron-depleted nitrogen-free cyclic group, —C(Q 1 )(Q 2 )-, —Si(Q 1 )(Q 2 )-, —B(Q 1 )-, and —N(Q 1 )-; and 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ), 
 
         a11 is selected from 1, 2, and 3, 
         Q 1  to Q 3 , Q 21  to Q 23  and Q 31  to Q 33  are each the same as respectively defined in connection with Formulae 4-1 to 4-3, and 
         wherein, in Formula 8-1, 
         R 81  to R 88  are each independently selected from hydrogen, deuterium, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and 
         * indicates a binding site to a neighboring atom. 
       
     
     
         9 . The organic light-emitting device of  claim 1 , wherein the second compound further comprises substitution group linked to at least one carbon atom (C) of the triazine group, and
 the substitution group is selected from:   a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group;   a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, a diazadibenzothiophenyl group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), —N(Q 31 )(Q 32 ), —P(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O)(Q 31 ), —S(═O) 2 (Q 31 ), —P(═O)(Q 31 )(Q 32 ), and —P(═S)(Q 31 )(Q 32 ); and   —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —-S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), and   wherein Q 1  to Q 3  and Q 31  to Q 33  are each independently selected from a phenyl group, a biphenyl group, a naphthyl group, a phenalenyl group, an anthracenyl group, a phenanthrenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a benzoquinoxalinyl group, a benzoquinazolinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group.   
     
     
         10 . The organic light-emitting device of  claim 9 , wherein the second compound further comprises a second linking group,
 the substitution group is linked to the triazine group through the second linking group. and   the second linking group is selected from a benzene group, a naphthalene group, a phenalene group, an anthracene group, a fluoranthene group, a triphenylene group, a phenanthrene group, a pyrene group, a chrysene group, a perylene 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 phthalazine group, a naphthyridine group, a quinoxaline group, a benzoquinoxaline group, a quinazoline group, a benzoquinazoline group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group; and   a fluoranthene group, a triphenylene group, a phenanthrene group, a pyrene group, a chrysene group, a perylene 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 phthalazine group, a naphthyridine group, a quinoxaline group, a benzoquinoxaline group, a quinazoline group, a benzoquinazoline group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group, each substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, an indeno fluorenyl group, an indolofluorenyl group, a benzofurofluorenyl group, a benzothienofluorenyl group, an indenocarbazolyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, an indenodibenzofuranyl group, an indolodibenzofuranyl group, a benzofurodibenzofuranyl group, a benzothienodibenzofuranyl group, an indenodibenzothiophenyl group, an indolodibenzothiophenyl group, a benzofurodibenzothiophenyl group, a benzothienodibenzothiophenyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a benzoisoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, an azafluorenyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, a diazafluorenyl group, a diazacarbazolyl group, a diazadibenzofuranyl group, and a diazadibenzothiophenyl group.   
     
     
         11 . The organic light-emitting device of  claim 1 , wherein the second compound is represented by Formula 2: 
       
         
           
           
               
               
           
         
         wherein in Formula 2, 
         L 21  to L 23  are each independently selected from a substituted or unsubstituted C 5 -C 30  carbocyclic group and a substituted or unsubstituted C 1 -C 30  heterocyclic group, 
         a21 to a23 are each independently selected from 0, 1, and 2, and 
         R 21  to R 23  are each independently selected from a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), 
         at least one substituent of 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, the substituted monovalent non-aromatic condensed heteropolycyclic group, the substituted C 5 -C 60  carbocyclic group, and the substituted C 1 -C 60  heterocyclic group is selected from:
 deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
 a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone 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 6 o 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, —Si(Q 11 )(Q 12 )(Q 13 ), —N(Q 11 )(Q 12 ), —B(Q 11 )(Q 12 ), —C(═O)(Q 11 ), —S(═O) 2 (Q 11 ), and —P(═O)(Q 11 )(Q 12 ); 
 a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; 
 a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a 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, —Si(Q 21 )(Q 22 )(Q 23 ), —N(Q 21 )(Q 22 ), —B(Q 21 )(Q 22 ), —C(═O)(Q 21 ), —S(═O) 2 (Q 21 ), and —P(═O)(Q 21 )(Q 22 ); and 
 —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), and 
 
         wherein Q 1  to Q 3 , Q 21  to Q 23  and Q 31  to Q 33  are each the same as respectively defined Formulae 4-1 to 4-3, and 
         Q 11  to Q 13  are each the same as Q 1  to Q 3 . 
       
     
     
         12 . The organic light-emitting device of  claim 1 , wherein the third compound comprises ligand group linked to the platinum (Pt) or iridium (Ir),
 the ligand group is selected from a bidentate ligand, tridentate ligand and tetradentate ligand, and   the ligand group comprises carbene moiety.   
     
     
         13 . The organic light-emitting device of  claim 1 , wherein the third compound is represented by Formula 3: 
       
         
           
           
               
               
           
         
         wherein in Formula 3, 
         M 31  is platinum (Pt) or iridium (Ir), 
         L 31  is a ligand represented by one of Formulae 3A to 3D, 
         L 32  is selected from a monodentate ligand, a bidentate ligand, and a tridentate ligand, 
         n31 is 1 or 2, and 
         n32 is selected from 0, 1, 2, 3, and 4, 
         wherein in Formulae 3A to 3D, 
         A 31  to A 34  are each independently selected from a C 5 -C 30  carbocyclic group and a C 1 -C 30  heterocyclic group, 
         T31 to T34 are each independently selected from a single bond, a double bond, *—O—*′, *—S—*′, *—C(═O)—*′, *—S(═O)—*′, *—C(R 35 )(R 36 )—*′, *—C(R 35 )═C(R 36 )—*′, *—C(R 35 )═*′, *—Si(R 35 )(R 36 )—*′, *—B(R 35 )—*′, *—N(R 35 )—*′, and *—P(R 35 )—*′, 
         k31 to k34 are each independently selected from 1, 2, and 3, 
         Y 31  to Y 34  are each independently selected from a single bond, *—O—*′, *—S—*′, *—C(R 37 )(R 38 )—*′, *—Si(R 37 )(R 38 )—*′, *—B(R 37 )—*′, *—N(R 37 )—*′, and *—P(R 37 )—*′, 
         * 1 , * 2 , * 3 , and * 4  each indicate a binding site to M 31 , 
         R 31  to R 38  are each independently selected from 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 substituted or unsubstituted C 1 -C 60  alkyl group, a substituted or unsubstituted C 2 -C 60  alkenyl group, a substituted or unsubstituted C 2 -C 60  alkynyl group, a substituted or unsubstituted C 1 -C 60  alkoxy group, a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), -C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), wherein R 31  to R 38  are optionally linked to each other to form a substituted or unsubstituted C 5 -C 60  carbocyclic group or a substituted or unsubstituted C 1 -C 60  heterocyclic group, 
         b31 to b34 are each independently an integer from 0 to 10, and 
         Q 1  to Q 3  are each the same as respectively defined in connection with Formulae 4-1 to 4-3. 
       
     
     
         14 . The organic light-emitting device of  claim 1 , wherein A 41  and A 42  are each independently selected from a group represented by Formula 12, —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), and —N(Q 1 )(Q 2 ): 
       
         
           
           
               
               
           
         
         wherein, in Formula 12, 
         X 121  is selected from O, S, N(R 123 ), and C(R 123 )(R 124 ), 
         X 122  is selected from a single bond, O, S, N(R 125 ), and C(R 125 )(R 126 ), 
         A 121  and A 122  are each independently selected from a benzene group, a naphthalene group, a phenalene group, an anthracene group, a fluoranthene group, a triphenylene group, a phenanthrene group, a pyrene group, a chrysene group, a perylene group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group, 
         R 121  to R 126  are each independently selected from:
 a binding site, hydrogen, deuterium, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ), and 
 a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, and a dinaphthothiophenyl group, each substituted with at least one selected from deuterium, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, —Si(Q 21 )(Q 22 )(Q 23 ), —B(Q 21 )(Q 22 ), and —N(Q 21 )(Q 22 ), wherein R 123  and R 124  are optionally linked to each other to form a π electron-depleted nitrogen-free cyclic group, R 125  and R 126  are optionally linked to each other to form a π electron-depleted nitrogen-free cyclic group, and at least one selected from R 121  to R 126  is the binding site, and 
 
         b121 and b122 are each independently selected from 1, 2, 3, 4, 5, and 6. 
       
     
     
         15 . The organic light-emitting device of  claim 1 , wherein D 41  and D 42  are each independently selected from:
 —F, a cyano group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, an oxadiazole group, an isoxadiazole group, a thiazole group, an isothiazole group, a thiadiazole group, an isothiadiazole group, a pyridine group, a pyrazine group, a pyridazine group, a pyrimidine group, a triazine group, a quinoline group, an isoquinoline group, a naphthyridine group, a quinoxaline group, a quinazoline group, and a group represented by one of Formulae 13-1 to 13-3;   a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, an oxadiazole group, an isoxadiazole group, a thiazole group, an isothiazole group, a thiadiazole group, an isothiadiazole group, a pyridine group, a pyrazine group, a pyridazine group, a pyrimidine group, a triazine group, a quinoline group, an isoquinoline group, a naphthyridine group, a quinoxaline group, and a quinazoline group, each substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group;   a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, an oxadiazole group, an isoxadiazole group, a thiazole group, an isothiazole group, a thiadiazole group, an isothiadiazole group, a pyridine group, a pyrazine group, a pyridazine group, a pyrimidine group, a triazine group, a quinoline group, an isoquinoline group, a naphthyridine group, a quinoxaline group, and a quinazoline group, each substituted with at least one selected from a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group that are each independently substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group;   a C 1 -C 20  alkyl group, a benzene group, biphenyl group, terphenyl group, a naphthalene group, a phenanthrene group, a triphenylene group, a chrysene group, a fluoranthene group, a fluorene group, a carbazole group, a dibenzofuran group, a dibenzothiophene group, a benzofluorene group, a benzocarbazole group, a benzonaphthofuran group, a benzonaphthothiophene group, a dibenzofluorene group, a dibenzocarbazole group, a dinaphthofuran group, and a dinaphthothiophene group, each substituted with at least one selected from —F, a cyano group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group;   a C 1 -C 20  alkyl group, a benzene group, biphenyl group, terphenyl group, a naphthalene group, a phenanthrene group, a triphenylene group, a chrysene group, a fluoranthene group, a fluorene group, a carbazole group, a dibenzofuran group, a dibenzothiophene group, a benzofluorene group, a benzocarbazole group, a benzonaphthofuran group, a benzonaphthothiophene group, a dibenzofluorene group, a dibenzocarbazole group, a dinaphthofuran group, and a dinaphthothiophene group, each substituted with at least one selected from a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group that are each independently substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group; and   a C 1 -C 20  alkyl group, a benzene group, biphenyl group, terphenyl group, a naphthalene group, a phenanthrene group, a triphenylene group, a chrysene group, a fluoranthene group, a fluorene group, a carbazole group, a dibenzofuran group, a dibenzothiophene group, a benzofluorene group, a benzocarbazole group, a benzonaphthofuran group, a benzonaphthothiophene group, a dibenzofluorene group, a dibenzocarbazole group, a dinaphthofuran group, and a dinaphthothiophene group, each substituted with at least one selected from a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, and a dinaphthothiophenyl group that are each independently substituted with at least one selected from —F, a cyano group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group:   
       
         
           
           
               
               
           
         
       
       and
 wherein, in Formulae 13-1 to 13-3, 
 X 131  is selected from C(═O), S(═O), S(═O) 2 , P(═O)(R 134 ), and P(═S)(R 134 ), 
 X 132  is selected from O, S, C(═O), S(═O), S(═O) 2 , P(═O)(R 135 ), and P(═S)(R 135 ), 
 k132 is 0 or 1, wherein, when k132 is 0, —(X 132 ) k132 — is a direct link, 
 Y 131  is selected from O and S, 
 A 131  and A 132  are each independently selected from a benzene group, a naphthalene group, a phenalene group, an anthracene group, a fluoranthene group, a triphenylene group, a phenanthrene group, a pyrene group, a chrysene group, a perylene group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group, 
 R 131  to R 135  are each independently selected from:
 a binding site, hydrogen, deuterium, —F, a cyano group, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group; and 
 a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group, each substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, an isoxazolyl group, an oxadiazolyl group, an isoxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, an isothiadiazolyl group, a pyridinyl group, a pyrazinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a naphthyridinyl group, a quinoxalinyl group, and a quinazolinyl group, wherein at least one selected from R 131  to R 135  is the binding site, and 
 
 b131 and b132 are each independently selected from 1, 2, 3, 4, 5, and 6. 
 
     
     
         16 . The organic light-emitting device of  claim 1 , wherein L 41  and L 42  are each independently selected from:
 a benzene group, a naphthalene group, a phenalene group, an anthracene group, a fluoranthene group, a triphenylene group, a phenanthrene group, a pyrene group, a chrysene group, a perylene group, a fluorene group, a carbazole group, a dibenzofuran group, a dibenzothiophene group, —C(Q 1 )(Q 2 )- and —Si(Q 1 )(Q 2 )-; and   a benzene group, a naphthalene group, a phenalene group, an anthracene group, a fluoranthene group, a triphenylene group, a phenanthrene group, a pyrene group, a chrysene group, a perylene group, a fluorene group, a carbazole group, a dibenzofuran group, and a dibenzothiophene group, each substituted with at least one selected from deuterium, a C 1 -C 20  alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylenyl group, a chrysenyl group, a fluoranthenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzofluorenyl group, a benzocarbazolyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, a dibenzofluorenyl group, a dibenzocarbazolyl group, a dinaphthofuranyl group, a dinaphthothiophenyl group, —C(Q 31 )(Q 32 )(Q 33 ), and —Si(Q 31 )(Q 32 )(Q 33 ).   
     
     
         17 . The organic light-emitting device of  claim 1 , wherein:
 the first electrode is an anode,   the second electrode is a cathode,   the organic layer further comprises a hole transport region between the first electrode and the emission layer and/or an electron transport region between the emission layer and the second electrode,   the hole transport region comprises a hole injection layer, a hole transport layer, an emission auxiliary layer, and/or an electron blocking layer, and   the electron transport region comprises a hole blocking layer, an electron transport layer, and/or an electron injection layer.   
     
     
         18 . An apparatus comprising:
 a thin-film transistor comprising a source electrode, a drain electrode,   an activation layer, and a sealing part; and   the organic light-emitting device of  claim 1 ,   wherein the first electrode of the organic light-emitting device is electrically connected to the source electrode or the drain electrode of the thin-film transistor.   
     
     
         19 . The apparatus of  claim 18 , wherein the apparatus is at least one selected from a biometric authentication apparatus, personal computers, mobile phones, digital cameras, electronic organizers, electronic dictionaries, electronic game machines, medical instruments, electronic thermometers, sphygmomanometers, blood glucose meters, pulse measurement devices, pulse wave measurement devices, electrocardiogram displays, ultrasonic diagnostic devices, endoscope displays, fish finders, measuring instruments, vehicle meters, aircraft meters, vessel meters, and projectors. 
     
     
         20 . An organic light-emitting device comprising:
 a first electrode;   a second electrode facing the first electrode; and   an organic layer between the first electrode and the second electrode,   wherein the organic layer comprises an emission layer and a hole blocking layer disposed on the emission layer,   the emission layer comprises a first compound, a second compound, a third compound, and a fourth compound,   the hole blocking layer comprises a hole blocking material represented by Formula 2,   the first compound comprises a first carbazole group and a second carbazole group linked to the first carbazole group;   the second compound comprises a triazine group;   the third compound comprises a metal complex containing platinum (Pt) or iridium (Ir);   the fourth compound is represented by any one of Formulae 4-1 to 4-3; and   the first compound, the second compound, the third compound, and the fourth compound are different from each other,   the first compound, the hole blocking material, the third compound, and the fourth compound are different from each other,   the second compound and the hole blocking material are the same as or different from each other:   
       
         
           
           
               
               
           
         
         wherein in Formula 2, 
         L 21  to L 23  are each independently selected from a substituted or unsubstituted C 5 -C 30  carbocyclic group and a substituted or unsubstituted C 1 -C 30  heterocyclic group, 
         a21 to a23 are each independently selected from 0, 1, and 2, and 
         R 21  to R 23  are each independently selected from a substituted or unsubstituted C 3 -C 10  cycloalkyl group, a substituted or unsubstituted C 1 -C 10  heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10  cycloalkenyl group, a substituted or unsubstituted heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60  aryl group, a substituted or unsubstituted C 6 -C 60  aryloxy group, a substituted or unsubstituted C 6 -C 60  arylthio group, a substituted or unsubstituted C 1 -C 60  heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —C(Q 1 )(Q 2 )(Q 3 ), —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), —N(Q 1 )(Q 2 ), —P(Q 1 )(Q 2 ), —C(═O)(Q 1 ), —S(═O)(Q 1 ), —S(═O) 2 (Q 1 ), —P(═O)(Q 1 )(Q 2 ), and —P(═S)(Q 1 )(Q 2 ), 
         wherein in Formulae 4-1 to 4-3, 
         A 41  and A 42  are each independently selected from:
 a π electron-depleted nitrogen-free cyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), —B(Q 1 )(Q 2 ), and —N(Q 1 )(Q 2 ); 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ); and 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one π electron-depleted nitrogen-free cyclic group that is substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-free cyclic group, —C(Q 21 )(Q 22 )(Q 23 ), —Si(Q 21 )(Q 22 )(Q 23 ), —B(Q 21 )(Q 22 ), and —N(Q 21 )(Q 22 ), 
 
         m41 and m42 are each independently selected from 1, 2, and 3, 
         D 41  and D 42  are each independently selected from:
 —F, a cyano group, a π electron-depleted nitrogen-containing cyclic group, a C(═O)-containing group, a P(═O)-containing group, and a P(═S)-containing group; 
 a π electron-depleted nitrogen-containing cyclic group, a C(═O)-containing group, a P(═O)-containing group, and a P(═S)-containing group, each substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group, and a π electron-depleted nitrogen-free cyclic group; 
 a π electron-depleted nitrogen-containing cyclic group, a C(═O)-containing group, a P(═O)-containing group, and a P(═S)-containing group, each substituted with at least one selected from a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group and a π electron-depleted nitrogen-free cyclic group that are each independently substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group, and a π electron-depleted nitrogen-free cyclic group; 
 a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group, each substituted with at least one selected from —F, a cyano group, and a π electron-depleted nitrogen-containing cyclic group; 
 a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group, each substituted with at least one π electron-depleted nitrogen-containing cyclic group that is substituted with at least one selected from deuterium, —F, a cyano group, a C 1 -C 60  alkyl group, a π electron-depleted nitrogen-containing cyclic group, and a π electron-depleted nitrogen-free cyclic group; and 
 a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group, each substituted with at least one selected from a C 1 -C 60  alkyl group and a π electron-depleted nitrogen-free cyclic group that are each independently substituted with at least one selected from —F, a cyano group, and a π electron-depleted nitrogen-containing cyclic group, 
 
         n41 and n42 are each independently selected from 1, 2, and 3, 
         L 41  and L 42  are each independently selected from:
 a π electron-depleted nitrogen-free cyclic group, —C(Q 1 )(Q 2 )-, —Si(Q 1 )(Q 2 )-, —B(Q 1 )-, and —N(Q 1 )-; and 
 a π electron-depleted nitrogen-free cyclic group substituted with at least one selected from deuterium, a C 1 -C 60  alkyl group, air electron-depleted nitrogen-free cyclic group, —C(Q 31 )(Q 32 )(Q 33 ), —Si(Q 31 )(Q 32 )(Q 33 ), —B(Q 31 )(Q 32 ), and —N(Q 31 )(Q 32 ), and 
 
         a41 and a42 are each independently selected from 0, 1, 2, and 3, 
         wherein in Formulae 2 and 4-1 to 4-3, 
         at least one substituent of 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, the substituted monovalent non-aromatic condensed heteropolycyclic group, the substituted C 5 -C 60  carbocyclic group, and the substituted C 1 -C 60  heterocyclic group is selected from:
 deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
 a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone 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 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, —Si(Q 11 )(Q 12 )(Q 13 ), —N(Q 11 )(Q 12 ), —B(Q 11 )(Q 12 ), —C(═O)(Q 11 ), —S(═O) 2 (Q 11 ), and —P(═O)(Q 11 )(Q 12 ); 
 a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; 
 a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a C 1 -C 60  heteroaryloxy group, a C 1 -C 60  heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a 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, —Si(Q 21 )(Q 22 )(Q 23 ), —N(Q 21 )(Q 22 ), —B(Q 21 )(Q 22 ), —C(═O)(Q 21 ), —S(═O) 2 (Q 21 ), and —P(═O)(Q 21 )(Q 22 ), and 
 
         —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), —B(Q 31 )(Q 32 ), —C(═O)(Q 31 ), —S(═O) 2 (Q 31 ), and —P(═O)(Q 31 )(Q 32 ), and 
         wherein Q 1  to Q 3 , Q 11  to Q 13 , Q 21  to Q 23  and Q 31  to Q 33  are each independently selected from 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 C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a 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, a biphenyl group, and a terphenyl group.