Abstract: This invention relates to an organic semiconductor device comprising a substrate bearing an organic layer sandwiched between electrode structures wherein the organic layer comprises a polymer of general Formula (I): wherein X is selected from H, CN, F, Cl, Br, COOCH3. Y is given by the following general Formula (II): wherein A is a phenyl group which may be further substituted in 1 or 2 or 3 positions with groups independently selected from C1-8 alkyl, CN, F, Cl; B and C are both phenyl groups which may be further substituted, independently of each other, in 1 or 2 or 3 or 4 or 5 positions with groups independently selected from C1-8 alkyl, CN, F, Cl; A, B and C may also be, independently of each other, selected from pyrimidine, pyridazine and pyridine; m=5-20,000.