NOVELTY - Polymeric semiconductor comprises: polythiophene derived from benzodithiophene monomer units (I), with a number average molecular weight of 1000-400000 Daltons; and at least one group exhibiting a bivalent linkage, comprising an aromatic or heteroaromatic electron acceptor compound and/or an aromatic or heteroaromatic compound.    USE - The polymeric semiconductor is useful in electronic devices, preferably thin film transistors or photovoltaic devices (all claimed), preferably polymer solar cells. The thin film transistor is useful in active matrix liquid crystal displays, organic light-emitting diodes, e-papers, radio-frequency identification tags and photovoltaics.    ADVANTAGE - The polymeric semiconductor exhibits: low bandgap and broad light absorption range and thus increases the efficiency of the electronic devices; low weight; and improved flexibility.    DETAILED DESCRIPTION - Polymeric semiconductor comprises: polythiophene derived from benzodithiophene monomer units of formula (I), with a number average molecular weight of 1000-400000 Daltons; and at least one group exhibiting a bivalent linkage, comprising an aromatic or heteroaromatic electron acceptor compound and/or an aromatic or heteroaromatic compound.R1, R2 = H, hydrocarbon group and/or hetero atom.    An INDEPENDENT CLAIM is also included for preparing the polymeric semiconductor comprising the polythiophene, comprising reacting benzoquinone-dithiophene with a reagent of formula (M-R11) to form an intermediate compound, reducing the obtained intermediate compound to form 4,8-disubstituted benzodithiophene (I), substituting the second and sixth positions of the benzodithiophene with at least one boron reagent or at least one halogen atom, copolymerizing at least one group exhibiting a bivalent linkage, at the second and sixth positions of the benzodithiophene to obtain a repeating unit, and copolymerizing the repeating unit to obtain the polymeric semiconductor.    M = MgX1 or Li;    X1 = halo; and    R11 = hydrocarbon group.    DESCRIPTION OF DRAWING(S) - The drawings 1 and 2 show schematic a representation of the thin film transistor configurations comprising the polymeric semiconductor.    Semiconductor layer (12)    dielectric gate layer (14)    Substrate (16)    Gate electrode (18)    Source electrode (20)