Patent ID: 7608680

Claim:
A triarylamine polymer represented by formula (1): wherein Ar 1 and Ar 2 , are different from each other and are, independent of each other, any one of the following formulas (4) to (8): wherein R 2 and R 3 are, independent of each other, a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkenyl group, an aryl group, an arylamino group or a heteroaryl group, R 2 may, together with one or more substituents, form a condensed ring, A is S, O, SO 2 , CO, CH 2 or(CH 3 ) 2 , b is an integer of from 0 to 4, c is an integer of from 2 to 4, and d is an integer of from 1 to 4, Ar 3 , Ar 4 , Ar 5 , Ar 6 and Ar 7 are, independent of one another, an unsubstituted or substituted C 6-60 aromatic group, and Ar 3 and Ar 4 are the same, and m is an integer of at least 1, wherein the triarylamine polymer has a weight average molecular weight of from 16000 to 100,000 as calculated as polystyrene.