Patent ID: 7807993

Claim:
A compound of formula 8 wherein R 15 , R 16 , and R 17 each independently are the same or different and each independently represents an optionally substituted C 1 -C 40 carbyl or hydrocarbyl group; an optionally substituted C 1 -C 40 alkoxy group; an optionally substituted C 6 -C 40 aryloxy group; an optionally substituted C 7 -C 40 alkylaryloxy group; an optionally substituted C 2 -C 40 alkoxycarbonyl group; or an optionally substituted C 7 -C 40 aryloxycarbonyl group; A represents silicon or germanium; one or more of the carbon atoms of the polyacene skeleton is or are optionally replaced by a heteroatom selected from N, P, As, O, S, Se and Te; one or more of R 1 , R 2 , R 3 , R 4 , R 8 , R 9 , R 10 and R 11 is or are F and the ones of R 1 , R 2 , R 3 , R 4 , R 8 , R 9 , R 10 and R 11 which are not F, are H; or R 2 and R 3 and R 9 and R 10 together with the carbon atoms to which they are attached form an optionally substituted C 4 -C 10 saturated or unsaturated ring intervened by one or more oxygen or sulphur atoms or a group represented by formula —N(R a ), wherein R a is a hydrogen atom or a hydrocarbon group; and the ring positions of the polyacene skeleton other than the 1, 2, 3, 4, 6, 8, 9, 10, 11 and 13 positions are unsubstituted.