NOVELTY - A polymer compound (I), is new.    USE - For manufacturing photovoltaic conversion devices, preferably solar cells, solar batteries, solar modules or optical sensors (claimed).    ADVANTAGE - The polymer compound (I) provides improved photoelectric conversion efficiency of i.e. greater than or equal to 1.5%; exhibits properties such as optimized optical absorption, good charge transport characteristics and chemical stability in ambient conditions, low-temperature processability, large solubility in common solvents, and processing versatility (e.g. via various solution processes); exhibits semiconductor behavior such as optimized light absorption/charge separation in a photovoltaic device, charge transport/recombination/light emission in a light-emitting device, and/or high carrier mobility and/or good current modulation characteristics in a field-effect device; and possesses certain processing advantages such as solution-processability and/or good stability (e.g. air stability) in ambient conditions.    DETAILED DESCRIPTION - A polymer compound of formula (I), is new.    R1 and R2=H, halo, alkyl, alkoxy, alkylthio group, cyano or nitro;    R3=carboxyl (optionally substituted), halo, alkyl, alkoxy, alkylthio group, acyl, acyloxy, carboxyl, cyano or nitro;    R4-R6=H, alkyl, alkoxy or alkylthio;    X'=group of formula (i);    Y'=CR7R8 or N-R9;    k=number of linearly linked thiophene units integrated in the repeating unit, preferably 0-2;    n=number of repeating units, preferably 2-2000;    R7-R9=alkyl, aryl, arylalkyl, arylalkenyl, arylalkynyl, heterocyclic group (preferably a mono-valent heterocyclic group) or heterocyclic group with at least one S;    EG1 and EG2=end groups of the polymer compound and H, halo, trialkylstannyl (-Sn(Alkyl)3), boronic acid (-B(OH)2), boronic ester (-B(OAlkyl)2), an aryl or heteroaryl unit.    INDEPENDENT CLAIMS are included for the following:    (1) preparing the polymer (I); and    (2) a photovoltaic device, preferably a photoelectric conversion device, having an anode, a cathode, and an organic layer containing at least one of the polymer compound (I) disposed between the anode and the cathode.