Block copolymer and polymer light-emitting device

A block copolymer characterized by comprising:

• a block (A) comprising two or more different types of repeating units represented by the following formula (I), and a repeating unit represented by the following formula (II);
• and
• a block (B) comprising a repeating unit represented by the following formula (II), and a repeating unit represented by the following formula (III),
• wherein R1 and R6 independently represent a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an arylalkyl group, an arylalkoxy group, an arylalkylthio group, an arylalkenyl group, an arylalkynyl group, a monovalent heterocyclic group, a heterocyclic thio group, an amino group, a silyl group, an acyl group, an acyloxy group, an imine residue, an amide group, an acid imide group, a carboxyl group, a cyano group, or a nitro group,
• wherein R2, R3, R4, and R5 independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an arylalkyl group, an arylalkoxy group, an arylalkylthio group, an arylalkenyl group, an arylalkynyl group, a monovalent heterocyclic group, a heterocyclic thio group, an amino group, a silyl group, an acyl group, an acyloxy group, an imine residue, an amide group, an acid imide group, a carboxyl group, a cyano group, or a nitro group,
• m and n represent 1, and
• X1, and X3 represent a sulfur atom,
• X2 represents an oxygen atom, a sulfur atom, or —C(R7)═C(R8)— wherein R7 and R8 independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, an arylalkyl group, an arylalkoxy group, an arylalkylthio group, an arylalkenyl group, an arylalkynyl group, a monovalent heterocyclic group, a heterocyclic thio group, an amino group, a silyl group, an acyl group, an acyloxy group, an imine residue, an amide group, an acid imide group, a carboxyl group, a cyano group, or a nitro group,
• —Ar1— (II)
• wherein Ar1 represents an arylene group, and
• —Ar2— (III)
• wherein Ar2 represents a divalent aromatic amine residue.