LIGHT-EMITTING DEVICE AND ELECTRONIC APPARATUS INCLUDING THE SAME

1 . A light-emitting device comprising:

an anode;

a cathode facing the anode;

a first emission layer arranged on the anode and comprising a first phosphorescent emitter; and

a second emission layer arranged on the first emission layer and comprising a first fluorescent emitter and a second phosphorescent emitter,

wherein a decay time T decay (1) of the first emission layer is shorter than a decay time T decay (2) of the second emission layer.

2 . The light-emitting device of claim 1 , wherein the first emission layer and the second emission layer each independently comprise at least one of a first host or a second host.

3 . The light-emitting device of claim 2 , wherein the first host is a hole-transporting host, and the second host is an electron-transporting host.

4 . The light-emitting device of claim 2 , wherein the first host comprises at least one carbazole moiety, and the second host comprises at least one azine moiety.

5 . The light-emitting device of claim 2 , wherein the first host comprises a compound represented by Formula 1:

wherein, in Formulae 1 and 1A,

CY 11 to CY 14 are each independently an unsubstituted or substituted C 5 -C 30 carbocyclic group or an unsubstituted or substituted C 1 -C 30 heterocyclic group,

E 1 is a group represented by Formula 1A,

k 1 is an integer from 0 to 5,

n11 is an integer from 0 to 3,

n12 is an integer from 0 to 3,

R 11 to R 17 are each independently 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 2 -C 10 heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 6 -C 60 aryloxy group, a substituted or unsubstituted C 6 -C 60 arylthio group, a substituted or unsubstituted C 1 -C 60 heteroaryl group, a substituted or unsubstituted C 1 -C 60 heteroaryloxy group, a substituted or unsubstituted C 1 -C 60 heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), —Ge(Q 1 )(Q 2 )(Q 3 ), —N(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), or —P(═O)(Q 8 )(Q 9 ),

b15 and b16 are each independently an integer from 0 to 4,

b17 is an integer from 0 to 5,

b11 to b14 are each independently an integer from 0 to 10,

* indicates a binding site to a neighboring atom,

wherein Q 1 to Q 9 , are each independently 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 30 alkyl group, a substituted or unsubstituted C 2 -C 30 alkenyl group, a substituted or unsubstituted C 2 -C 30 alkynyl group, a substituted or unsubstituted C 1 -C 30 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 30 aryl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 6 -C 30 arylthio group, a substituted or unsubstituted C 1 -C 30 heteroaryl group, a substituted or unsubstituted C 1 -C 30 heteroaryloxy group, a substituted or unsubstituted C 1 -C 30 heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.

6 . The light-emitting device of claim 2 , wherein the second host comprises a compound represented by Formula 2:

wherein, in Formula 2,

CY 23 and CY 24 are each independently a C 5 -C 30 carbocyclic group or a C 1 -C 30 heterocyclic group,

X 21 is N or C(R 21a ), X 22 is N or C(R 22a ), X 23 is N or C(R 23a ), and at least one of X 21 to X 23 is N,

L 21 and L 22 are each independently a single bond, a substituted or unsubstituted C 3 -C 60 carbocyclic group, or a substituted or unsubstituted C 1 -C 60 heterocyclic group,

n21 and n22 are each independently an integer from 1 to 5,

R 21 to R 24 , R 21a , R 22a , and R 23a are each independently 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 2 -C 10 heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 6 -C 60 aryloxy group, a substituted or unsubstituted C 6 -C 60 arylthio group, a substituted or unsubstituted C 1 -C 60 heteroaryl group, a substituted or unsubstituted C 1 -C 60 heteroaryloxy group, a substituted or unsubstituted C 1 -C 60 heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q 1 )(Q 2 )(Q 3 ), —Ge(Q 1 )(Q 2 )(Q 3 ), —N(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), or —P(═O)(Q 8 )(Q 9 ),

b21 to b24 are each independently an integer from 1 to 10,

wherein Q 1 to Q 9 , are each independently 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 30 alkyl group, a substituted or unsubstituted C 2 -C 30 alkenyl group, a substituted or unsubstituted C 2 -C 30 alkynyl group, a substituted or unsubstituted C 1 -C 30 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 30 aryl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 6 -C 30 arylthio group, a substituted or unsubstituted C 1 -C 30 heteroaryl group, a substituted or unsubstituted C 1 -C 30 heteroaryloxy group, a substituted or unsubstituted C 1 -C 30 heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.

7 . The light-emitting device of claim 1 , wherein the first phosphorescent emitter and the second phosphorescent emitter each independently comprise a compound represented by Formula 3 or Formula 5:

wherein, in Formula 3,

M 31 is a transition metal,

X 31 to X 34 are each independently C or N,

two bonds of a bond between X 31 and M 31 , a bond between X 32 and M 31 , a bond between X 33 and M 31 , and a bond between X 34 and M 31 are each a coordinate bond, and the other two bonds are each a covalent bond,

CY 31 to CY 34 are each independently a C 5 -C 30 carbocyclic group or a C 1 -C 30 heterocyclic group,

L 31 is a single bond, a double bond, *—N(R 35a )—*′, *—B(R 35a )—*′, *—P(R 35a )—*′, *—C(R 35a )(R 35b )—*′, *—Si(R 35a )(R 35b )—*′, *—Ge(R 35a )(R 35b )—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O) 2 —*′, *—C(R 35a )═*′, *═C(R 35a )—*′, *—C(R 35a )═C(R 35b )—*′, *—C(═S)—*′, *—C═C—*′, a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

L 32 is a single bond, a double bond, *—N(R 36a )—*′, *—B(R 36a )—*′, *—P(R 36a )—*′, *—C(R 36a )(R 36b )—*′, *—Si(R 36a )(R 36b )—*′, *—Ge(R 36a )(R 36b )—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O) 2 —*′, *—C(R 36a )═*′, *═C(R 36a )—*′, *—C(R 36a )═C(R 36b )—*′, *—C(═S)—*′, *—C═C—*′, a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

L 33 is a single bond, a double bond, *—N(R 37a )—*′, *—B(R 37a )—*′, *—P(R 37a )—*′, *—C(R 37a )(R 37b )—*′, *—Si(R 37a )(R 37b )—*′, *—Ge(R 37a )(R 37b )—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O) 2 —*′, *—C(R 37a )═*′, *═C(R 37a )—*′, *—C(R 37a )═C(R 37b )—*′, *—C(═S)—*′, *—C═C—*′, a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

L 34 is a single bond, a double bond, *—N(R 38a )—*′, *—B(R 38a )—*′, *—P(R 38a )—*′, *—C(R 38a )(R 38b )—*′, *—Si(R 38a )(R 38b )—*′, *—Ge(R 38a )(R 38b )—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O) 2 —*′, *—C(R 38a )═*′, *═C(R 38a )—*′, *—C(R 38a )═C(R 38b )—*′, *—C(═S)—*′, *—C═C—*′, a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a , or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

n31 to n34 are each independently an integer from 0 to 5, and three or more of n31 to n34 are each independently an integer from 1 to 5,

when n31 is 0, L 31 is not present, when n32 is 0, L 32 is not present, when n33 is 0, L 33 is not present, and when n34 is 0, L 34 is not present,

when n31 is 2 or greater, at least two L 31 (s) are identical to or different from each other, when n32 is 2 or greater, at least two L 32 (s) are identical to or different from each other, when n33 is 2 or greater, at least two L 33 (s) are identical to or different from each other, and when n34 is 2 or greater, at least two L 34 (s) are identical to or different from each other,

R 31 to R 34 , R 35a , R 35b , R 36a , R 36b , R 37a , R 37b , R 38a , and R 38b are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF 5 , a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a 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 7 -C 60 arylalkyl group, a substituted or unsubstituted C 6 -C 60 aryloxy group, a substituted or unsubstituted C 6 -C 60 arylthio group, a substituted or unsubstituted C 1 -C 60 heteroaryl group, a substituted or unsubstituted C 2 -C 60 heteroarylalkyl 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 ), —Ge(Q 1 )(Q 2 )(Q 3 ), —N(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), —P(═O)(Q:)(Q 9 ), or —P(Q 8 )(Q 9 ),

b31 to b34 are each independently an integer from 0 to 20,

at least two of R 31 (s) in the number of b31 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

at least two of R 32 (s) in the number of b32 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

at least two of R 33 (s) in the number of b33 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

at least two of R 34 (s) in the number of b34 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

at least two of R 31 to R 34 , R 35a , R 35b , R 36a , R 36b , R 37a , R 37b , R 38a , and R 38b are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10a ,

R 10a is the same as described in connection with R 31 ,

M 51 (L 51 ) n51 (L 52 ) n52   Formula 5

wherein, in Formula 5,

M 51 is a transition metal,

L 51 is a ligand represented by Formula 5A,

L 52 is a ligand represented by Formula 5B,

n51 is 1, 2, or 3, and n52 is 0, 1, or 2,

Y 51 to Y 54 are each independently C or N,

CY 51 to CY 54 are each independently a C 5 -C 30 carbocyclic group or a C 1 -C 30 heterocyclic group,

R 51 to R 54 are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF 5 , a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C 1 -C 60 alkyl group, a substituted or unsubstituted C 2 -C 60 alkenyl group, a substituted or unsubstituted C 2 -C 60 alkynyl group, a substituted or unsubstituted C 1 -C 60 alkoxy group, a substituted or unsubstituted C 1 -C 60 alkylthio group, a substituted or unsubstituted C 3 -C 10 cycloalkyl group, a substituted or unsubstituted C 1 -C 10 heterocycloalkyl group, a substituted or unsubstituted C 3 -C 10 cycloalkenyl group, a substituted or unsubstituted C 1 -C 10 heterocycloalkenyl group, a substituted or unsubstituted C 6 -C 60 aryl group, a substituted or unsubstituted C 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 ), —Ge(Q 1 )(Q 2 )(Q 3 ), —N(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), —P(═O)(Q 8 )(Q 9 ), or —P(Q 8 )(Q 9 ),

b51 to b54 are each independently an integer from 1 to 20,

* and *′ each indicate a binding site to a neighboring atom,

wherein Q 1 to Q 9 , are each independently 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 30 alkyl group, a substituted or unsubstituted C 2 -C 30 alkenyl group, a substituted or unsubstituted C 2 -C 30 alkynyl group, a substituted or unsubstituted C 1 -C 30 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 30 aryl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 6 -C 30 arylthio group, a substituted or unsubstituted C 1 -C 30 heteroaryl group, a substituted or unsubstituted C 1 -C 30 heteroaryloxy group, a substituted or unsubstituted C 1 -C 30 heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.

8 . The light-emitting device of claim 7 , wherein M 31 and M 51 are each independently palladium (Pd), platinum (Pt), or gold (Au).

9 . The light-emitting device of claim 7 , wherein n34 is 0,

X 31 is C, and

a bond between X 31 and M 31 is a coordinate bond.

10 . The light-emitting device of claim 7 , wherein, in Formula 3, CY 32 to CY 34 each independently comprise a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a furan group, a thiophene group, a silole group, an indene group, a fluorene group, an indole group, a carbazole group, a benzofuran group, a dibenzofuran group, a benzothiophene group, a dibenzothiophene group, a benzosilole group, a dibenzosilole group, an azafluorene group, an azacarbazole group, an azadibenzofuran group, an azadibenzothiophene group, an azadibenzosilole group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, an indazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a benzotriazole group, a diazaindene group, a triazaindene group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group.

11 . The light-emitting device of claim 7 , wherein the first phosphorescent emitter and the second phosphorescent emitter each independently comprise an organometallic compound represented by Formula 3-1 or Formula 3-2:

wherein, in Formulae 3-1 and 3-2,

b31 to b34 are each independently an integer from 0 to 20,

M 31 , CY 32 , CY 33 , CY 34 , X 32 , X 33 , X 34 , L 31 , L 32 , L 33 , n31, n32, n33, R 32 , R 33 , R 34 , a32, a33, and a34 are each as described in Formula 3, and

R 311 to R 317 are each independently as described in connection with R 31 .

12 . The light-emitting device of claim 11 , wherein, in Formulae 3-1 and 3-2, at least one of R 311 to R 317 comprises a C 1 -C 20 alkyl group, a C 6 -C 60 aryl group, or a C 7 -C 60 arylakyl group, each unsubstituted or substituted with at least one of a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a phenyl group, a cumyl group, or a combination thereof.

13 . The light-emitting device of claim 1 , wherein the first fluorescent emitter is represented by Formula 4:

wherein, in Formula 4,

Z is B or N,

CY 41 to CY 43 are each independently a C 5 -C 30 carbocyclic group or a C 1 -C 30 heterocyclic group,

L 41 is a single bond, *—N(R 44 )—*′, *—B(R 44 )—*′, *—P(R 44 )—*′, *—C(R 44 )(R 45 )—*′, *—Si(R 44 )(R 45 )—*′, *—Ge(R 44 )(R 45 )—*′, *—O—*′, *—S—*′, *—Se—*′, *—C(═O)—*′, or *—S(═O) 2 —*′,

L 42 is a single bond, *—N(R 46 )—*′, *—B(R 46 )—*′, *—P(R 46 )—*′, *—C(R 46 )(R 47 )—*′, *—Si(R 46 )(R 47 )—*′, *—Ge(R 46 )(R 47 )—*′, *—O—*′, *—S—*′, *—Se—*′, *—C(═O)—*′, or *—S(═O) 2 —*′,

L 43 is a single bond, *—N(R 48 )—*′, *—B(R 48 )—*′, *—P(R 48 )—*′, *—C(R 48 )(R 49 )—*′, *—Si(R 48 )(R 49 )—*′, *—Ge(R 48 )(R 49 )—*′, *—O—*′, *—S—*′, *—Se—*′, *—C(═O)—*′, or *—S(═O) 2 —*′,

n41 to n43 are each independently 0 or 1,

when n41 is 0, L 41 is not present, when n42 is 0, L 42 is not present, and when n43 is 0, L 43 is not present,

R 41 to R 49 are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF 5 , a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a 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 7 -C 60 arylalkyl group, a substituted or unsubstituted C 6 -C 60 aryloxy group, a substituted or unsubstituted C 6 -C 60 arylthio group, a substituted or unsubstituted C 1 -C 60 heteroaryl group, a substituted or unsubstituted C 2 -C 60 heteroarylalkyl 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 ), —Ge(Q 1 )(Q 2 )(Q 3 ), —N(Q 4 )(Q 5 ), —B(Q 6 )(Q 7 ), —P(═O)(Q 8 )(Q 9 ), or —P(Q 8 )(Q 9 ),

b41 to b43 are each independently an integer from 1 to 20,

at least two of R 41 (s) in the number of b41 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10b ,

at least two of R 42 (s) in the number of b42 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10b ,

at least two of R 43 (s) in the number of b43 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10b ,

at least two of R 41 to R 49 are optionally bonded to each other to form a C 5 -C 30 carbocyclic group unsubstituted or substituted with at least one R 10a or a C 1 -C 30 heterocyclic group unsubstituted or substituted with at least one R 10b ,

R 10b is the same as described in connection with R 41 ,

* and *′ each indicate a binding site to a neighboring atom,

wherein Q 1 to Q 9 , are each independently 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 30 alkyl group, a substituted or unsubstituted C 2 -C 30 alkenyl group, a substituted or unsubstituted C 2 -C 30 alkynyl group, a substituted or unsubstituted C 1 -C 30 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 30 aryl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 6 -C 30 arylthio group, a substituted or unsubstituted C 1 -C 30 heteroaryl group, a substituted or unsubstituted C 1 -C 30 heteroaryloxy group, a substituted or unsubstituted C 1 -C 30 heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.

14 . The light-emitting device of claim 13 , wherein, in Formula 4, Z is B.

15 . The light-emitting device of claim 13 , wherein the first fluorescent emitter is represented by any one of Formulae 4-1 to 4-8:

wherein, in Formulae 4-1 to 4-8,

Z 1 and Z 2 are each independently as described in connection with Z,

Y 41 and Y 42 are each independently as described in connection with L 41 and L 42 , respectively,

Y 44 and Y 45 are each independently as described in connection with Y 41 and Y 42 , respectively,

R 411 is as described in connection with R 41 , R 421 is as described in connection with R 42 , R 431 and R 432 are each independently as described in connection with R 43 , R 441 is as described in connection with R 41 , R 451 is as described in connection with R 42 , and R 461 is as described in connection with R 43 ,

a411 is an integer from 0 to 4,

a421 is an integer from 0 to 3,

a431 is an integer from 0 to 4,

a441 is an integer from 0 to 4,

a451 is an integer from 0 to 3, and

a461 is an integer from 0 to 4.

16 . The light-emitting device of claim 1 , wherein a thickness of the second emission layer is greater than a thickness of the first emission layer.

17 . The light-emitting device of claim 1 , wherein a thickness of the first emission layer is less than or equal to half of a total thickness of the first emission layer and the second emission layer.

18 . The light-emitting device of claim 1 , wherein a thickness of the first emission layer is greater than or equal to one-tenth a total thickness of the first emission layer and the second emission layer.

19 . The light-emitting device of claim 1 , wherein T decay (1) is about 0.5 microseconds to about 5 microseconds.

20 . The light-emitting device of claim 1 , wherein T decay (2) is about 1 microseconds to about 20 microseconds.