Copolymer, electroluminescence device material including copolymer, and electroluminescence device

A copolymer having a structural unit represented by Chemical Formula 1:

• wherein, in Chemical Formula 1,
• Ar1 and Ar2 are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 ring-member atoms,
• L1 is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 30 carbon atoms,
• each R1 is independently a hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 ring-member atoms, wherein two R1's are optionally linked to provide a ring structure,
• a is an integer of 0, 1, 2, or 3, and
• Y is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms or a substituted or unsubstituted aromatic heterocyclic group having 3 to 60 ring-member atoms.