NOVELTY - A polymer comprising at least one optionally substituted annulated thienyl-vinylene-thienyl unit (I) or (II) and pi -conjugated unit as repeating units, is new. The pi -conjugated unit is a conjugated linear linker comprising one or more unsaturated bonds, or a conjugated cyclic linker comprising one or more carbocyclic and/or heterocyclic rings. The annulated thienyl-vinylene-thienyl unit is covalently linked to the pi -conjugated unit by thiophene rings or specific groups.    USE - New polymer is used for organic thin-film transistor and organic photovoltaic device (all claimed) e.g. bulk heterojunction (BHJ) solar cell. Uses include but are not limited to organic light-emitting transistor, organic LED, printable circuit, electrochemical capacitor and sensor.    ADVANTAGE - The polymer has stable optical absorption, excellent charge transport characteristics, chemical stability, low-temperature processability, solubility in common solvent, and processing versatility. The organic photovoltaic device obtained using the polymer has excellent power conversion efficiency.    DETAILED DESCRIPTION - A polymer comprising at least one optionally substituted annulated thienyl-vinylene-thienyl unit of formula (I) or (II) and pi -conjugated unit as repeating units, is new. The pi -conjugated unit is a conjugated linear linker comprising one or more unsaturated bonds, or a conjugated cyclic linker comprising one or more carbocyclic and/or heterocyclic rings. The annulated thienyl-vinylene-thienyl unit is covalently linked to the pi -conjugated unit by thiophene rings or groups (Cy1 and Cy2).    Cy1,CY2= 5- or 6-membered saturated carbocyclyl.    INDEPENDENT CLAIMS are included for the following:    (1) organic thin-film transistor, which comprises polymeric semiconductor component and polymeric semiconductor component comprising the polymer; and    (2) organic photovoltaic device, which comprises anode, cathode, optionally one or more anode interlayers, optionally one or more cathode interlayers, and polymeric semiconductor component comprising blend material comprising electron-acceptor compound and electron-donor compound between the anode and the cathode. The electron-donor compound is polymer.