Conjugated polymers and their use in optoelectronic devices

An optoelectronic device comprising an anode, a cathode optionally one or more anode interlayers, optionally one or more cathode interlayers, and in between the anode and the cathode a photoactive component, the photoactive component comprising a fullerene compound and a random copolymer, wherein the random copolymer is represented by formula (IVa) or (VIIIa):

• wherein:
• Ra and Rb are C6-40 alkyl groups;
• Rc and Rd are C6-40 alkyl groups identical to or different from Ra and Rb;
• R5a is a C6-40 alkyl group;
• R5b is H or a C6-40 alkyl group;
• R6a and R6b are identical or different and independently are selected from —R5, —OR5, —SR5 and —Y—R5, wherein Y is a divalent C6-14 aryl group or a divalent 5-14 membered heteroaryl group;
• and R5, at each occurrence, independently is a C6-40 alkyl group optionally substituted with 1-5 substituents independently selected from a halogen, —CN, —NH2, —NH(C1-20 alkyl), —N(C1-20 alkyl)2, —SiH3, —SiH(C1-20 alkyl)2, —SiH2(C1-20 alkyl), —Si(C1-20 alkyl)3, an —O—C1-20 alkyl group, and an —S—C1-20 alkyl group;
• and
• p, q, s and t are real numbers representing mole fractions, wherein 0.025≦p≦0.975, 0.025≦q≦0.975, 0.025≦s≦0.975, 0.025≦t≦0.975, and the sum of p, q, s, and t is about 1;
• provided that at least one of the following is true:
• (a) Rc and Rd are C6-40 alkyl groups different from Ra and Rb, (b) R5a is a C6-40 alkyl group and R5b is H;
• and (c) R6a and R6b are different;
• and
• wherein the random copolymer has a molecular weight in the range of about 1,000 to about 500,000.