Heterocyclic compound and organic light-emitting device including the same
A heterocyclic compound is represented by Formula 1. An 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 and including an emission layer, wherein the organic light-emitting device includes at least one of the heterocyclic compound.
1. An organic light-emitting device comprising:
a first electrode;
a second electrode facing the first electrode;
an organic layer between the first electrode and the second electrode and comprising an emission layer; and
at least one heterocyclic compound represented by Formula 1:
wherein, in Formulae 1 and 2-1 to 2-7,
X 1 to X 3 are each independently N or C(R 15 ), wherein at least one selected from X 1 to X 3 is N,
L 1 to L 3 are each independently a substituted or unsubstituted C 3 -C 60 carbocyclic group or a substituted or unsubstituted C 1 -C 60 heterocyclic group,
a1 to a3 are each independently an integer from 0 to 3,
Ar 1 to Ar 3 are each independently a group represented by one selected from Formulae 2-1 to 2-7,
Y 1 is O or S,
R 1 to R 3 and R 6 to R 16 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 2 -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 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 ),
R 4 and R 5 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 2 -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, an unsubstituted C 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 ),
b3 is an integer from 0 to 3, b4 is an integer from 0 to 4, and b5 is an integer from 0 to 5,
in the groups included in the heterocyclic compound represented by Formula 1, at least one selected from the substituents R 1 to R 11 of Formulae 2-1 to 2-6 is —Si(Q 1 )(Q 2 )(Q 3 ),
when Ar 1 is a group represented by Formula 2-7, a1 is 0, when Ar 2 is a group represented by Formula 2-7, a2 is 0, and when Ar 3 is a group represented by Formula 2-7, a3 is 0,
when Ar 1 is Formula 2-3 and L 1 is a benzene group, Ar 2 is Formula 2-3 and L 2 is a benzene group, or Ar 3 is Formula 2-3 and L 3 is a benzene group at least one selected from R 4 and R 5 selected from 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 2 -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, an unsubstituted C 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 );
when Ar 1 is a group represented by Formula 2-3, at least one of R 4 and R 5 in Formula 2-3 is —Si(Q 1 )(Q 2 )(Q 3 ) and Ar 2 and Ar 3 are each a group represented by Formula 2-1, at least one of Ar 2 and Ar 3 is that in Formula 1, b5 is an integer selected from 1 to 5, and R 1 is selected from 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 2 -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 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 );
when Ar 2 is a group represented by Formula 2-3, at least one of R 4 and R 5 in Formula 2-3 is —Si(Q 1 )(Q 2 )(Q 3 ) and Ar 1 and Ar 3 are each a group represented by Formula 2-1, at least one of Ar 2 and Ar 3 is that in Formula 1, b5 is an integer selected from 1 to 5, and R 1 is selected from 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 2 -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 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 );
when Ar 3 is a group represented by Formula 2-3, at least one of R 4 and R 5 in Formula 2-3 is —Si(Q 1 )(Q 2 )(Q 3 ) and Ar 1 and Ar 2 are each a group represented by Formula 2-1, at least one of Ar 1 and Ar 2 is that in Formula 1, b5 is an integer selected from 1 to 5, and R 1 is selected from 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 2 -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 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 );
when Ar 1 is a group represented by Formula 2-7, Ar 2 and Ar 3 are not a group represented by Formula 2-1 and L 2 and L 3 are not a benzene group, when Ar 2 is a group represented by Formula 2-7, Ar 1 and Ar 3 are not a group represented by Formula 2-1 and L 1 and L 3 are not a benzene group, and when Ar 3 is a group represented by Formula 2-7, Ar 1 and Ar 2 are not a group represented by Formula 2-1 and L 1 and L 2 are not a benzene group, and
a case in which each of Ar 1 to Ar 3 is a group represented by Formula 2-1 is excluded,
at least one substituent of the substituted C 3 -C 60 carbocyclic group, the substituted C 1 -C 60 heterocyclic group, the substituted C 1 -C 60 alkyl group, the substituted C 2 -C 60 alkenyl group, the substituted C 2 -C 60 alkynyl group, the substituted C 1 -C 60 alkoxy group, the substituted C 3 -C 10 cycloalkyl group, the substituted C 2 -C 10 heterocycloalkyl group, the substituted C 3 -C 10 cycloalkenyl group, the substituted C 2 -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 2 -C 60 heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is selected from:
deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono 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 hydrazino group, a hydrazono 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 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 monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl 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, a biphenyl group, and a terphenyl 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 hydrazino group, a hydrazono 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 monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, a terphenyl 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 ),
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 hydrazino group, a hydrazono 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 aryl group substituted with a C 1 -C 60 alkyl group, a C 1 -C 60 heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group; and
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 aryl group substituted with a C 1 -C 60 alkyl group, a C 1 -C 60 heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl 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 hydrazino group, a hydrazono group, a C 1 -C 60 alkyl group, and —Si(R a )(R b )(R c ),
R a to R c 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 2 -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 2 -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,
* indicates a binding site to a neighboring atom, and
the heterocyclic compound represented by Formula 1 does not include Compound 1:
2. The organic light-emitting device of claim 1 , wherein:
the first electrode is an anode,
the second electrode is a cathode,
the organic layer comprises at least one of the heterocyclic compound,
the organic layer further comprises a hole transport region between the first electrode and the emission layer and an electron transport region between the emission layer and the second electrode,
the hole transport region comprises a hole injection layer, a hole transport layer, an emission auxiliary layer, an electron blocking layer, or any combination thereof, and
the electron transport region comprises a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.
3. The organic light-emitting device of claim 1 , wherein:
the emission layer comprises a dopant and a host, and
the host comprises at least one of the heterocyclic compound.
4. The organic light-emitting device of claim 3 , wherein:
the dopant is a phosphorescent dopant.
5. The organic light-emitting device of claim 3 , wherein:
the dopant comprises an organometallic complex represented by Formula 401:
wherein, in Formulae 401 and 402,
M is selected from iridium (Ir), platinum (Pt), palladium (Pd), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), rhodium (Rh), and thulium (Tm),
L 401 is selected from ligands represented by Formula 402, and xc1 is 1, 2, or 3, wherein, when xc1 is two or more, two or more L 401 (s) are identical to or different from each other,
L 402 is an organic ligand, and xc2 is an integer from 0 to 4, wherein, when xc2 is two or more, two or more L 402 (s) are identical to or different from each other,
X 401 to X 404 are each independently nitrogen or carbon,
X 401 and X 403 are linked via a single bond or a double bond, and X 402 and X 404 are linked via a single bond or a double bond,
A 401 and A 402 are each independently a C 5 -C 60 carbocyclic group or a C 1 -C 60 heterocyclic group,
X 405 is a single bond, *—O—*′, *—S—*′, *—C(═O)—*′, *—N(Q 411 )-*′, *—C(Q 411 )(Q 412 )-*′, *—C(Q 411 )=C(Q 412 )-*′, *—C(Q 411 )=*′, or (Q 411 ) *═C═*′, wherein Q 411 and Q 412 are each independently hydrogen, deuterium, a C 1 -C 20 alkyl group, a C 1 -C 20 alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group,
X 406 is a single bond, O, or S,
R 401 and R 402 are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, a substituted or unsubstituted C 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 401 )(Q 402 )(Q 403 ), —N(Q 401 )(Q 402 ), —B(Q 401 )(Q 402 ), —C(═O)(Q 401 ), —S(═O) 2 (Q 401 ), and —P(═O)(Q 401 )(Q 402 ), wherein Q 401 to Q 403 are each independently selected from a C 1 -C 10 alkyl group, a C 1 -C 10 alkoxy group, a C 6 -C 20 aryl group, and a C 1 -C 20 heteroaryl group,
xc11 and xc12 are each independently an integer from 0 to 10, and
* and *′ in Formula 402 each indicate a binding site to M in Formula 401.
6. The organic light-emitting device of claim 2 , wherein:
the hole transport region further comprises a p-dopant having a lowest unoccupied molecular orbital (LUMO) energy level of about −3.5 eV or less.
7. The organic light-emitting device of claim 2 , wherein:
the electron transport region comprises an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, a rare earth metal compound, an alkali metal complex, an alkaline earth metal complex, a rare earth metal complex, or any combination thereof.
8. The organic light-emitting device of claim 1 , wherein:
the emission layer comprises a first emission layer configured to emit a first color light,
the organic light-emitting device further comprises, between the first electrode and the second electrode, i) at least one second emission layer configured to emit a second color light or ii) the at least one second emission layer configured to emit the second color light and at least one third emission layer configured to emit a third color light,
a maximum emission wavelength of the first color light, a maximum emission wavelength of the second color light, and a maximum emission wavelength of the third color light are identical to or different from each other, and
the first color light and the second color light are emitted in a form of mixed light, or the first color light, the second color light, and the third color light are emitted in a form of mixed light.
9. A heterocyclic compound represented by Formula 1:
wherein, in Formulae 1 and 2-1 to 2-7,
X 1 to X 3 are each independently N or C(R 15 ), wherein at least one selected from X 1 to X 3 is N,
L 1 to L 3 are each independently a substituted or unsubstituted C 3 -C 60 carbocyclic group or a substituted or unsubstituted C 1 -C 60 heterocyclic group,
a1 to a3 are each independently an integer from 0 to 3,
Ar 1 to Ar 3 are each independently a group represented by one selected from Formulae 2-1 to 2-7,
Y 1 is O or S,
R 1 to R 3 and R 6 to R 16 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 2 -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 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 ),
R 4 and R 5 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 2 -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, an unsubstituted C 2 -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 1 )(Q 2 ), —B(Q 1 )(Q 2 ), —S(═O) 2 (Q 1 ), and —P(═O)(Q 1 )(Q 2 ),
b3 is an integer from 0 to 3, b4 is an integer from 0 to 4, and b5 is an integer from 0 to 5,
in the groups included in the heterocyclic compound represented by Formula 1, at least one selected from the substituents R 1 to R 11 of Formulae 2-1 to 2-6 is —Si(Q 1 )(Q 2 )(Q 3 ),
when Ar 1 is a group represented by Formula 2-7, a1 is 0, when Ar 2 is a group represented by Formula 2-7, a2 is 0, and when Ar 3 is a group represented by Formula 2-7, a3 is 0,
when Ar 1 is Formula 2-3 and L 1 is a benzene group, Ar 2 is Formula 2-3 and L 2 is a benzene group, or Ar 3 is Formula 2-3 and L 3 is a benzene group at least one selected from R 4 and R 5 is not hydrogen;
when Ar 1 is a group represented by Formula 2-3, at least one of R 4 and R 5 in Formula 2-3 is —Si(Q 1 )(Q 2 )(Q 3 ) and Ar 2 and Ar 3 are each a group represented by Formula 2-1, at least one of Ar 2 and Ar 3 is that in Formula 1, R 1 is not hydrogen and b5 is an integer selected from 1 to 5;
when Ar 2 is a group represented by Formula 2-3, at least one of R 4 and R 5 in Formula 2-3 is —Si(Q 1 )(Q 2 )(Q 3 ) and Ar 1 and Ar 3 are each a group represented by Formula 2-1, at least one of Ar 2 and Ar 3 is that in Formula 1, R 1 is not hydrogen and b5 is an integer selected from 1 to 5;
when Ar 3 is a group represented by Formula 2-3, at least one of R 4 and R 5 in Formula 2-3 is —Si(Q 1 )(Q 2 )(Q 3 ) and Ar 1 and Ar 2 are each a group represented by Formula 2-1, at least one of Ar 1 and Ar 2 is that in Formula 1, R 1 is not hydrogen and b5 is an integer selected from 1 to 5;
when Ar 1 is a group represented by Formula 2-7, Ar 2 and Ar 3 are not a group represented by Formula 2-1 and L 2 and L 3 are not a benzene group, when Ar 2 is a group represented by Formula 2-7, Ar 1 and Ar 3 are not a group represented by Formula 2-1 and L 1 and L 3 are not a benzene group, and when Ar 3 is a group represented by Formula 2-7, Ar 1 and Ar 2 are not a group represented by Formula 2-1 and L 1 and L 2 are not a benzene group, and
a case in which each of Ar 1 to Ar 3 is a group represented by Formula 2-1 is excluded,
at least one substituent of the substituted C 3 -C 60 carbocyclic group, the substituted C 1 -C 60 heterocyclic group, the substituted C 1 -C 60 alkyl group, the substituted C 2 -C 60 alkenyl group, the substituted C 2 -C 60 alkynyl group, the substituted C 1 -C 60 alkoxy group, the substituted C 3 -C 10 cycloalkyl group, the substituted C 2 -C 10 heterocycloalkyl group, the substituted C 3 -C 10 cycloalkenyl group, the substituted C 2 -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 2 -C 60 heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is selected from:
deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono 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 hydrazino group, a hydrazono 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 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 monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl 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, a biphenyl group, and a terphenyl 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 hydrazino group, a hydrazono 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 monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, a terphenyl 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 ),
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 hydrazino group, a hydrazono 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 aryl group substituted with a C 1 -C 60 alkyl group, a C 1 -C 60 heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group; and
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 aryl group substituted with a C 1 -C 60 alkyl group, a C 1 -C 60 heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl 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 hydrazino group, a hydrazono group, a C 1 -C 60 alkyl group, and —Si(R a )(R b )(R c ),
R a to R c 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 2 -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 2 -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,
* indicates a binding site to a neighboring atom, and
the heterocyclic compound represented by Formula 1 does not include Compound 1:
10. The heterocyclic compound of claim 9 , wherein:
L 1 to L 3 are each independently selected from:
a benzene group, a pentalene group, an indene group, a naphthalene group, an azulene group, a heptalene group, an indacene group, an acenaphthalene group, a fluorene group, a spiro-bifluorene group, a spiro-benzofluorene-fluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pyrrole group, a thiophene group, a furan group, a silole group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a triazine group, a benzofuran group, a benzothiophene group, a benzosilole group, a dibenzosilole group, a quinoline group, an isoquinoline group, a benzimidazole group, an imidazopyridine group, and an imidazopyrimidine group;
a benzene group, a pentalene group, an indene group, a naphthalene group, an azulene group, a heptalene group, an indacene group, an acenaphthalene group, a fluorene group, a spiro-bifluorene group, a spiro-benzofluorene-fluorene group, a benzofluorene group, a dibenzofluorene group, a phenalene group, a phenanthrene group, an anthracene group, a fluoranthene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a pyrrole group, a thiophene group, a furan group, a silole group, an imidazole group, a pyrazole group, a thiazole group, an isothiazole group, an oxazole group, an isoxazole group, a pyridine group, a pyrazine group, a pyrimidine group, a pyridazine group, a triazine group, a benzofuran group, a benzothiophene group, a benzosilole group, a dibenzosilole group, a quinoline group, an isoquinoline group, a benzimidazole group, an imidazopyridine group, and an imidazopyrimidine group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, 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 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, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzofuranyl group, a benzothiophenyl group, —Si(Q 31 )(Q 32 )(Q 33 ), —N(Q 31 )(Q 32 ), and —B(Q 31 )(Q 32 ), and
Q 31 to Q 33 are each independently selected from 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, and a pyridinyl group.
11. The heterocyclic compound of claim 9 , wherein:
L 1 to L 3 are each independently selected from groups represented by Formulae 3-1 to 3-27:
wherein, in Formulae 3-1 to 3-27,
Y 11 is selected from C(Z 3 )(Z 4 ), N(Z 5 ), Si(Z 6 )(Z 7 ), O, and S,
Z 1 to Z 7 are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, 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 naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, a silolyl 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, a benzofuranyl group, a benzothiophenyl group, a benzosilolyl group, a dibenzosilolyl group, and —Si(Q 31 )(Q 32 )(Q 33 ),
Q 31 to Q 33 are each independently selected from 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, and a pyridinyl group,
d2 is an integer from 0 to 2,
d3 is an integer from 0 to 3,
d4 is an integer from 0 to 4,
d6 is an integer from 0 to 6,
d8 is an integer from 0 to 8, and
* and *′ each indicate a binding site to a neighboring atom.
12. The heterocyclic compound of claim 9 , wherein:
at least one selected from Ar 1 to Ar 3 is a group that is different from the others thereof.
13. The heterocyclic compound of claim 9 , wherein:
at least one selected from Ar 1 to Ar 3 is a group represented by one selected from Formulae 2-2 to 2-4.
14. The heterocyclic compound of claim 9 , wherein:
i) Ar 1 and Ar 2 are each a group represented by Formula 2-1, and Ar 3 is a group represented by Formula 2-2;
ii) Ar 1 and Ar 2 are each a group represented by Formula 2-1, and Ar 3 is a group represented by Formula 2-3;
iii) Ar 1 and Ar 2 are each a group represented by Formula 2-1, and Ar 3 is a group represented by Formula 2-4;
iv) Ar 1 is a group represented by Formula 2-1, and Ar 2 and Ar 3 are each a group represented by Formula 2-3;
v) Ar 1 is a group represented by Formula 2-1, and Ar 2 and Ar 3 are each a group represented by Formula 2-4;
vi) Ar 1 and Ar 2 are each a group represented by Formula 2-3, and Ar 3 is a group represented by Formula 2-6;
vii) Ar 1 is a group represented by Formula 2-1, Ar 2 is a group represented by Formula 2-2, and Ar 3 is a group represented by Formula 2-3; or
viii) Ar 1 is a group represented by Formula 2-1, Ar 2 is a group represented by Formula 2-3, and Ar 3 is a group represented by Formula 2-6.
15. The heterocyclic compound of claim 9 , wherein:
i) when Ar 1 is a group represented by Formula 2-1, at least one selected from R 1 (s) in the number of b5 is —Si(Q 1 )(Q 2 )(Q 3 ), and
ii) when Ar 1 and Ar 2 are each a group represented by Formula 2-3 and Ar 3 is a group represented by Formula 2-6, at least one selected from R 10 (s) in the number of b4 and R 11 (s) in the number of b3 is —Si(Q 1 )(Q 2 )(Q 3 ).
16. The heterocyclic compound of claim 9 , wherein:
Ar 1 to Ar 3 are each independently a group represented by one selected from Formulae 2-1(1) to 2-1(3), 2-2(1) and 2-2(2), 2-3(1) and 2-3(2), 2-4(1) and 2-4(2), and 2-6(1) to 2-6(4):
wherein, in Formulae 2-1(1) to 2-1(3), 2-2(1) and 2-2(2), 2-3(1) and 2-3(2), 2-4(1) and 2-4(2), and 2-6(1) to 2-6(4),
Z 11 to Z 15 are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, 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 naphthyl group, a fluorenyl group, a spiro-bifluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, a silolyl 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, a benzofuranyl group, a benzothiophenyl group, a benzosilolyl group, a dibenzosilolyl group, and —Si(Q 31 )(Q 32 )(Q 33 ),
Q 31 to Q 33 are each independently selected from 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, and a pyridinyl group,
e3 is an integer from 0 to 3,
e4 is an integer from 0 to 4,
e5 is an integer from 0 to 5,
Ph indicates a phenyl group, and
* indicates a binding site to a neighboring atom.
17. The heterocyclic compound of claim 16 , wherein:
at least one selected from Ar 1 to Ar 3 is a group represented by one selected from Formulae 2-1(2), 2-1(3), 2-2(2), 2-3(2), 2-6(3), and 2-6(4).
18. The heterocyclic compound of claim 9 , wherein:
Ar 1 to Ar 3 are each independently a group represented by one selected from Formulae 4-1 to 4-21:
wherein, in Formulae 4-1 to 4-21,
Ph indicates a phenyl group, and t-Bu indicates a tert-butyl group, and
* indicates a binding site to a neighboring atom.
19. The heterocyclic compound of claim 9 , wherein:
i) X 1 to X 3 are each N;
ii) X 1 and X 2 are each N, and X 3 is C(R 15 );
iii) X 1 and X 3 are each N, and X 2 is C(R 15 );
iv) X 2 and X 3 are each N, and X 1 is C(R 15 );
v) X 1 is N, and X 2 and X 3 are each C(R 15 );
vi) X 2 is N, and X 1 and X 3 are each C(R 15 ); or
vii) X 3 is N, and X 1 and X 2 are each C(R 15 ),
and R 15 is hydrogen.
20. The heterocyclic compound of claim 9 , wherein:
the heterocyclic compound is selected from Compounds 2 to 9 and 11 to 59: