Patent ID: 8889265

Claim:
A copolymer consisting of two or more repeating units selected from the group consisting of arylene groups, divalent heterocyclic groups and divalent aromatic amine groups, with the proviso that at least one of the repeating units is a divalent aromatic amine group represented by formula (7): wherein Ar 9 , Ar 10 , and Ar 11 each independently represent a phenylene group, naphthalenediyl group, anthracenediyl group, phenanthrenediyl group, pentalenediyl group, indenediyl group, heptalenediyl group, indacenediyl group, stilbenediyl group or 3,3′-alkoxystilbenediyl group, and Ar 12 and Ar 13 each independently represent an aryl group; q represents an integer of 1 to 3, wherein the copolymer has, on at least one of molecular chain ends, an aromatic end group selected from a monovalent heterocyclic group and aryl groups having a formula weight of 90 or more, the aromatic end group having a substituent selected from the group consisting of alkyl groups, and the copolymer shows fluorescence in the solid state and has a polystyrene-reduced weight-average molecular weight of 10 3 to 10 8 .