Organic light-emitting device

Abstract

An organic light-emitting device including a first electrode, a second electrode facing the first electrode, and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer comprises an emission layer and satisfies Equations 1 and 2, E T1(HOST) −E T1(AD) >0.05 eV  Equation 1 E S1(FD) −E S1(AD) <0 eV,  Equation 2 wherein in Equation 1, E T1(HOST) is a triplet energy (eV) of the host, and E T1(AD) is a triplet energy (eV) of the auxiliary dopant, and wherein in Equation 2, E S1(FD) is a singlet energy (eV) of the fluorescent dopant, and E S1(AD) is a singlet energy (eV) of the auxiliary dopant, wherein the emission layer comprises a host, an auxiliary dopant, and a fluorescent dopant, and wherein the auxiliary dopant is selected from compounds represented by Formula 1: wherein in Formula 1, Ar 1 and R 11 to R 16 are the same as described in the specification.

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 disposed between the first electrode and the second electrode,   wherein the organic layer comprises an emission layer and satisfies Equations 1 and 2,   wherein the emission layer comprises a host, an auxiliary dopant, and a fluorescent dopant, and   wherein the auxiliary dopant is selected from compounds represented by Formula 1:
     E   T1(HOST)   −E   T1(AD) >0.05 electron Volts  Equation 1
 
     E   S1(FD)   −E   S1(AD) <0 electron Volts,  Equation 2
 
   wherein in Equation 1,   E T1(HOST)  is a triplet energy (electron Volts) of the host, and   E T1(AD)  is a triplet energy (electron Volts) of the auxiliary dopant, and   wherein in Equation 2,   E S1(FD)  is a singlet energy (electron Volts) of the fluorescent dopant, and   E S1(AD)  is a singlet energy (electron Volts) of the auxiliary dopant,   
       
         
           
           
               
               
           
         
         wherein 
         Ar 1  in Formula 1 is a group represented by Formula 2, 
         ring A 1  in Formula 2 is a group represented by Formula 2A, 
         ring A 2  in Formula 2 is a group represented by Formula 2B, 
         X 1  in Formula 2B is N(R 17 ), O, or S, 
         R 1  to R 17  in Formulae 1, 2, 2A, and 2B are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, —Si(Q 1 )(Q 2 )(Q 3 ), —N(Q 4 )(Q 5 ), and —B(Q 6 )(Q 7 ), 
         * in Formula 2 indicates a binding site to a neighboring atom, 
         at least one of substituents of the substituted C 1 -C 60  alkyl group, substituted C 2 -C 60  alkenyl group, substituted C 2 -C 60  alkynyl group, substituted C 1 -C 60  alkoxy group, substituted C 3 -C 10  cycloalkyl group, substituted C 1 -C 10  heterocycloalkyl group, substituted C 3 -C 10  cycloalkenyl group, substituted C 1 -C 10  heterocycloalkenyl group, substituted C 6 -C 60  aryl group, substituted C 6 -C 60  aryloxy group, substituted C 6 -C 60  arylthio group, substituted C 1 -C 60  heteroaryl group, substituted monovalent non-aromatic condensed polycyclic group, and substituted monovalent non-aromatic condensed heteropolycyclic group is selected from: 
         a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group; 
         a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, and a C 1 -C 60  alkoxy group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 11 )(Q 12 )(Q 13 ), —N(Q 14 )(Q 15 ), and —B(Q 16 )(Q 17 ); 
         a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group; 
         a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 21 )(Q 22 )(Q 23 ), —N(Q 24 )(Q 25 ), and —B(Q 26 )(Q 27 ); and 
         —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 34 )(Q 35 ), and —B(Q 36 )(Q 37 ), and 
         Q 1  to Q 7 , Q 11  to Q 17 , Q 21  to Q 27 , and Q 31  to Q 37  are each independently selected from a hydrogen, 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, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. 
       
     
     
         2 . The organic light-emitting device of  claim 1 , wherein Ar 1  in Formula 1 is selected from groups represented by Formulae 2-1 to 2-6: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         R 1  to R 10  and X 1  in Formulae 2-1 to 2-6 are the same as in  claim 1 , and 
         * indicates a binding site to a neighboring atom. 
       
     
     
         3 . The organic light-emitting device of  claim 1 , wherein X 1  in Formula 2B is N(R 17 ). 
     
     
         4 . The organic light-emitting device of  claim 1 , wherein X 1  in Formula 2B is N(R 17 ), and R 17  is selected from
 a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group; and   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, and —Si(Q 31 )(Q 32 )(Q 33 ), and   Q 31  to Q 33  are each independently selected from a hydrogen, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group.   
     
     
         5 . The organic light-emitting device of  claim 1 , wherein R 1  to R 14  are each independently selected from
 a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, and a C 1 -C 20  alkoxy group;   a C 1 -C 20  alkyl group and a C 1 -C 20  alkoxy group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof;   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group;   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a thiophenyl group, a furanyl group, a carbazolyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, and a dibenzocarbazolyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, and —Si(Q 31 )(Q 32 )(Q 33 ); and   —Si(Q 1 )(Q 2 )(Q 3 ), and   Q 1  to Q 3  and Q 31  to Q 33  are each independently selected from a hydrogen, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group.   
     
     
         6 . The organic light-emitting device of  claim 1 , wherein R 15  and R 16  are each independently selected from
 a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; and   a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzosilolyl group, a thiadiazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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 cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and —Si(Q 31 )(Q 32 )(Q 33 ), and   Q 31  to Q 33  are each independently selected from a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group.   
     
     
         7 . The organic light-emitting device of  claim 1 , wherein the auxiliary dopant is selected from Compounds 1 to 39: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         8 . The organic light-emitting device of  claim 1 , wherein the host has a triplet energy level of 2.9 electron Volts or greater. 
     
     
         9 . The organic light-emitting device of  claim 1 , wherein the host comprises a fluorene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, an indenocarbazole ring, an indolocarbazole ring, a benzofurocarbazole ring, a benzothienocarbazole ring, an acridine ring, a dihydroacridine ring, a triindolobenzene ring, or any combination thereof, or
 the host is a silicon compound or a phosphine oxide compound.   
     
     
         10 . The organic light-emitting device of  claim 1 , wherein the host is selected from compounds represented by Formulae 11-1 to 11-3: 
       
         
           
           
               
               
           
         
         wherein, in Formulae 11-1 to 11-3, 13, and 14, 
         Ar 11  and Ar 12  are each independently selected from groups represented by Formulae 13 and 14, 
         X 15  is N(R 22 ), O, or S, 
         X 1  is N or C(T 14 ), X 2  is N or C(T 15 ), X 3  is N or C(T 16 ), and at least one of X 1  to X 3  is N, 
         T 21  and T 22  are each independently selected from *-(L 21 ) a21 -Si(Q 41 )(Q 42 )(Q 43 ) and *-(L 21 ) a21 -P(═O)(Q 51 )(Q 52 ), 
         L 11  to L 13  and L 21  are each independently selected from 
         a single bond, O, S, Si(Q 61 )(Q 62 ), a phenylene group, a pyridinylene group, a pyrimidinylene group, a pyrazinylene group, a pyridazinylene group, a triazinylene group, a naphthylene group, a fluorenylene group, a carbazolylene group, a dibenzofuranylene group, and a dibenzothiophenylene group; and 
         a phenylene group, a pyridinylene group, a pyrimidinylene group, a pyrazinylene group, a pyridazinylene group, a triazinylene group, a naphthylene group, a fluorenylene group, a carbazolylene group, a dibenzofuranylene group, and a dibenzothiophenylene group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, —CF 3 , —CF 2 H, —CFH 2 , a phenyl group, a phenyl group substituted with a cyano group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 71 )(Q 72 )(Q 73 ), 
         a11 to a13 and a21 are each independently an integer selected from 0 to 5, two or more groups L 11  are identical to or different from each other when a11 is 2 or more, two or more groups L 12  are identical to or different from each other when a12 is 2 or more, two or more groups L 13  are identical to or different from each other when a13 is 2 or more, and two or more groups L 21  are identical to or different from each other when a21 is 2 or more, 
         CY 3  and CY 4  are each independently selected from a benzene, a naphthalene, a fluorene, a carbazole, a benzocarbazole, an indolocarbazole, a dibenzofuran, and a dibenzothiophene, 
         A 2  is selected from 
         a single bond, a C 1 -C 4  alkylene group, and a C 2 -C 4  alkenylene group; and 
         a C 1 -C 4  alkylene group and a C 2 -C 4  alkenylene group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 81 )(Q 82 )(Q 83 ), 
         T 11  to T 16 , R 22 , R 30 , and R 40  are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group (CN), 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, and —Si(Q 91 )(Q 92 )(Q 93 ), 
         b3 and b4 are each independently an integer selected from 0 to 10, 
         c1 is 0, 1, 2, or 3, 
         * indicates a binding site to a neighboring atom, 
         at least one of substituents of the substituted C 1 -C 60  alkyl group, substituted C 2 -C 60  alkenyl group, substituted C 2 -C 60  alkynyl group, substituted C 3 -C 10  cycloalkyl group, substituted C 1 -C 10  heterocycloalkyl group, substituted C 3 -C 10  cycloalkenyl group, substituted C 1 -C 10  heterocycloalkenyl group, substituted C 6 -C 60  aryl group, substituted C 6 -C 60  aryloxy group, substituted C 6 -C 60  arylthio group, substituted C 1 -C 60  heteroaryl group, substituted monovalent non-aromatic condensed polycyclic group, and substituted monovalent non-aromatic condensed heteropolycyclic group is selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q 101 )(Q 102 )(Q 103 ), and 
         Q 41  to Q 43 , Q 51 , Q 52 , Q 61 , Q 62 , Q 71  to Q 73 , Q 81  to Q 83 , Q 91  to Q 93 , and Q 101  to Q 103  are each independently selected from a hydrogen, a deuterium, a C 1 -C 60  alkyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group. 
       
     
     
         11 . The organic light-emitting device of  claim 10 , wherein Ar 11  and Ar 12  are each independently selected from groups represented by Formulae 13-1 to 13-8 and 14-1 to 14-8: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 13-1 to 13-8 and 14-1 to 14-8, 
         X 12  and X 14  are each independently C(R 37 )(R 38 ), N(R 39 ), O, or S, 
         X 15  and A 2  are the same as in  claim 10 , 
         R 31  to R 39  are each independently the same as R 30  in  claim 10 , 
         R 41  to R 44  are each independently the same as R 40  in  claim 10 , and 
         * indicates a binding site to a neighboring atom. 
       
     
     
         12 . The organic light-emitting device of  claim 10 , wherein Ar 11  and Ar 12  are each independently selected from groups represented by Formulae 17-1 to 17-19 and 18-1 to 18-8: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 17-1 to 17-19 and 18-1 to 18-8, 
         X 12  and X 14  are each independently C(R 37 )(R 38 ), N(R 39 ), O, or S, 
         X 15  is N(R 17 ), O, or S, 
         R′ and R″ are each independently selected from a hydrogen, a deuterium, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, 
         R 22 , R 30 , R 30a  to R 30c , and R 40  are each independently selected from 
         a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, —CF 3 , —CF 2 H, and —CFH 2 ; 
         a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; 
         a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, —CF 3 , —CF 2 H, —CFH 2 , a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and 
         —Si(Q 91 )(Q 92 )(Q 93 ), 
         Q 91  to Q 93  are each independently selected from a hydrogen, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group, and 
         * indicates a binding site to a neighboring atom. 
       
     
     
         13 . The organic light-emitting device of  claim 11 , wherein L 11  to L 13  and L 21  are each independently selected from a single bond, O, S, Si(Q 61 )(Q 62 ), and a group represented by one of Formulae 3-1 to 3-56: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 3-1 to 3-56, 
         Y 1  is selected from O, S, C(Z 3 )(Z 4 ), and N(Z 5 ), 
         Z 1  to Z 5  are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, —CF 3 , —CF 2 H, —CFH 2 , a phenyl group, a phenyl group substituted with a cyano group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 71 )(Q 72 )(Q 73 ), 
         Q 71  to Q 73  are each independently selected from a hydrogen, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, 
         d4 is an integer selected from 0 to 4, 
         d3 is an integer selected 0 to 3, 
         d2 is an integer selected 0 to 2, and 
         * and *′ each indicate a binding site to a neighboring atom. 
       
     
     
         14 . The organic light-emitting device of  claim 10 , wherein a group represented by *-(L 11 ) a11 -*′, *-(L 12 ) a12 -*′, *-(L 13 ) a13 -*′, and *-(L 21 ) a21 -*′ is selected from a single bond and groups represented by Formulae 4-1 to 4-42: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formulae 4-1 to 4-42, 
         X 21  is N or C(Z 21 ), X 22  is N or C(Z 22 ), X 23  is N or C(Z 23 ), X 24  is N or C(Z 24 ), X 31  is N or C(Z 31 ), X 32  is N or C(Z 32 ), X 33  is N or C(Z 33 ), X 34  is N or C(Z 34 ), X 41  is N or C(Z 41 ), X 42  is N or C(Z 42 ), X 43  is N or C(Z 43 ), and X 44  is N or C(Z 44 ), wherein each of X 21  to X 24  is not simultaneously N, wherein each of X 31  to X 34  is not simultaneously N, and wherein X 41  to X 44  is not simultaneously N, 
         Z 21  to Z 24 , Z 31  to Z 34  and Z 41  to Z 44  are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid 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, —CF 3 , —CF 2 H, —CFH 2 , a phenyl group, a phenyl group substituted with a cyano group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and —Si(Q 71 )(Q 72 )(Q 73 ), 
         Q 71  to Q 73  are each independently selected from a hydrogen, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, and 
         * and *′ each indicate a binding site to a neighboring atom. 
       
     
     
         15 . The organic light-emitting device of  claim 10 , wherein
 T 11  to T 16  are each independently selected from   a hydrogen, a deuterium, —F, a cyano group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, —CF 3 , —CF 2 H, and —CFH 2 ;   a C 1 -C 10  alkyl group and a C 1 -C 10  alkoxy group, each substituted with at least one selected from a deuterium, —F, a cyano group, —CF 3 , —CF 2 H, and —CFH 2 ;   a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group;   a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from a deuterium, —F, a cyano group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, —CF 3 , —CF 2 H, —CFH 2 , a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and   —Si(Q 91 )(Q 92 )(Q 93 ), and   Q 91  to Q 93  are each independently selected from a hydrogen, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group.   
     
     
         16 . The organic light-emitting device of  claim 10 , wherein
 Q 41  to Q 43 , Q 51 , and Q 52  are each independently selected from   a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and   a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from a deuterium, —F, a cyano group, a C 1 -C 10  alkyl group, a C 1 -C 10  alkoxy group, —CF 3 , —CF 2 H, —CFH 2 , a phenyl group, a biphenyl group, a terphenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group.   
     
     
         17 . The organic light-emitting device of  claim 1 , wherein the host is selected from Compounds H1 to H24: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         18 . The organic light-emitting device of  claim 1 , wherein the fluorescent dopant comprises a naphthalene core, a fluorene core, a spiro-bifluorene core, a benzofluorene core, a dibenzofluorene core, a phenanthrene core, an anthracene core, a fluoranthene core, a triphenylene core, a pyrene core, a chrysene core, a naphthacene core, a picene core, a perylene core, a pentaphene core, an indenoanthracene core, a tetracene core, a bisanthracene core, a core represented by one of Formulae 501-1 to 501-18, or any combination thereof: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         19 . The organic light-emitting device of  claim 1 , wherein the fluorescent dopant is selected from compounds represented by Formula 501: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein, in Formula 501, 
         Ar 501  is selected from 
         a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, a tetracene group, a bisanthracene group, and a group represented by one of Formulae 501-1 to 501-18; and 
         a naphthalene group, a fluorene group, a spiro-bifluorene group, a benzofluorene group, a dibenzofluorene group, a phenanthrene group, an anthracene group, a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pentaphene group, an indenoanthracene group, a tetracene group, a bisanthracene group, and a group represented by one of Formulae 501-1 to 501-18, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 60  alkyl group, a C 2 -C 60  alkenyl group, a C 2 -C 60  alkynyl group, a C 1 -C 60  alkoxy group, a C 3 -C 10  cycloalkyl group, a C 1 -C 10  heterocycloalkyl group, a C 3 -C 10  cycloalkenyl group, a C 1 -C 10  heterocycloalkenyl group, a C 6 -C 60  aryl group, a C 6 -C 60  aryloxy group, a C 6 -C 60  arylthio group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q 501 )(Q 502 )(Q 503 ) (wherein Q 501  to Q 503  are each independently selected from a hydrogen, a C 1 -C 60  alkyl group, a C 1 -C 60  alkoxy group, a C 6 -C 60  aryl group, a C 1 -C 60  heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group), 
         L 501  to L 503  are each independently selected from a substituted or unsubstituted C 3 -C 10  cycloalkylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkylene group, a substituted or unsubstituted C 3 -C 10  cycloalkenylene group, a substituted or unsubstituted C 1 -C 10  heterocycloalkenylene group, a substituted or unsubstituted C 6 -C 60  arylene group, a substituted or unsubstituted C 1 -C 60  heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group, 
         R 501  and R 502  are each independently selected from 
         a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazole group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and 
         a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C 1 -C 20  alkyl group, a C 1 -C 20  alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, 
         xd1 to xd3 are each independently selected from 0, 1, 2, and 3, and 
         xd4 is selected from 0, 1, 2, 3, 4, 5, and 6. 
       
     
     
         20 . The organic light-emitting device of  claim 1 , wherein the fluorescent dopant comprises any one of Compounds FD(1) to FD(14), any one of Compounds FD1 to FD13, or any combination thereof: