Dithienobenzo-thieno[3,2-B]thiophene-copolymer and its use as high performance solution processable semiconducting polymer

Dithienobenzo-thieno[3,2-b]thiophene-copolymers of the formula (I) wherein: pi is a monocyclic or polycyclic moiety optionally substituted with 1-4 Ra groups, wherein Ra, at each occurrence, is independently hydrogen or a) a halogen, b) -(CN, c) -NO2, d) oxo, e) -OH, f) C(Rb)2; g) a C1-20 alkyl group, h) a C2-20 alkenyl group, i) a C2-20 alkynyl group, j) a C1-20 alkoxy group, k) a C1-20 alkylthio group, l) a C1-20 haloalkyl group, m) a -Y-C3-10 cycloalkyl group, n) a -Y-C6-14 aryl group, o) a -Y-3-12 membered cycloheteroalkyl group, or p) a -Y-5-14 membered heteroaryl group, wherein each of the C1-20 alkyl group, the C2-20 alkenyl group, the C2-20 alkynyl group, the C3-10 cycloalkyl group, the C6-14 aryl or haloaryl group, the 3-12 membered cycloheteroalkyl group, and the 5-14 membered heteroaryl group is optionally substituted with 1-4 Rb groups; Y, at each occurrence, is independently a divalent C1-6 alkyl group, a divalent C1-6 haloalkyl group, or a covalent bond; and R1, R2, R3, at each occurrence, are independently H, a halogen, CN, a C1-30 alkyl group, a C2-30 alkenyl group, a C1-30 haloalkyl group, a C2-30 alkynyl group, a C1-30 alkoxy group, a C(O)-C1-20 alkyl group, a C(O)-OC1-20 alkyl group, a Y-C3-10 cycloalkyl group, a -Y-3-12 membered cycloheteroalkyl group, each optionally substituted with 1-5 substituents selected from a halogen, -CN, a C1-6 alkyl group, a C1-6 alkoxy group, and a C1-6 haloalkyl group, -L-Ar1, -L-Ar1-Ar1, -L-Ar1-R4, or -L-Ar1-Ar1-R4 and Y, at each occurrence, is independently a divalent C1-6 alkyl group, a divalent C1-6 haloalkyl group, or a covalent bond; n=0, 1, 2; and o=1-1000.