in Chemical Formula 1,

Q₁ and Q₂ are each independently a C_6-30 aromatic ring,

n is an integer of 1 to 3,

a and b are each independently an integer of 0 to 3,

X is a single bond; CR₃R₄; SiR₅R₆; NR₇; O; S; SO₂; or a substituent represented by Chemical Formula 2,

R₁ to R₇ are each independently hydrogen; deuterium; a substituted or unsubstituted C_1-60 alkyl; a substituted or unsubstituted C_1-60 alkoxy; a substituted or unsubstituted C_6-60 aryl; or a substituted or unsubstituted C_5-60 heteroaryl containing at least one heteroatom selected from the group consisting of N, O and S, or adjacent groups of R₁ to R₇ are bonded to each other to form a ring,

L is a single bond; a substituted or unsubstituted C_6-60 arylene; or a substituted or unsubstituted C_2-60 heteroarylene containing at least one heteroatom selected from the group consisting of N, O and S, and

Ar is an unsubstituted C_6-60 aryl; a C_6-60 aryl substituted with one or more substituents selected from the group consisting of deuterium, a cyano group, a nitro group, a carbonyl group, an ester group, an imide group, an amino group, a phosphine oxide group, an alkoxy group, an aryloxy group, an alkylthioxy group, an arylthioxy group, an alkylsulfoxy group, an arylsulfoxy group, a silyl group, a boron group, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, an aralkenyl group, an alkylaryl group, an alkylamine group, an aralkylamine group, a heteroarylamine group, an arylamine group, an arylphosphine group, and a heterocyclic group containing at least one of N, O and S atoms, or with a substituent in which two or more substituents of the above group of substituents of the C_6-60 aryl are connected to each other; a substituted or unsubstituted C_2-60 heteroaryl containing at least one heteroatom selected from the group consisting of N, O and S; or a di(C_6-60 aryl)phosphine oxide group.