A random copolymer comprising the monomer units A, B and C. In this random copolymer A comprises B comprises and C comprises an aryl group. Additionally, R1 R2, R3 and R4 are side chains independently selected from the group consisting of: H, Cl, F, CN, alkyl, alkoxy, alkylthio, ester, ketone and aryl groups. X1 and X2 are independently selected from the group consisting of: H, Cl, F, CN, alkyl, alkoxy, ester, ketone, amide and aryl groups.