NOVELTY - Composition comprises a polythiophene polymer having thienyl repeating units, where at least some of the thienyl repeating units not disposed at a polymer chain terminus are covalently or ionically bonded via respective linkers to respective fullerene groups.    USE - The composition is useful: for photovoltaic electrical generation; in a film; and in a photovoltaic device (all claimed), where the film is useful for assembly into arrays of photovoltaic generation cells or units for manufacturing solar panel.    ADVANTAGE - The composition: exhibits controllable degree of contact between the photo-excited electron-generating polythiophene and the electron-accepting fullerene, thus enhances photoefficiency of photovoltaic device; and provides flexible and inexpensive photovoltaic device.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a film comprising the composition;    (2) preparing the composition, comprising either contacting a polythiophene polymer bearing a linker precursor group and a fullerene suitable to react with the linker precursor group to form a polythiophene-linker-fullerene material, or polymerizing, in the presence of a metallic catalyst, a halothiophene organometallic reagent, where the reagent being prepared by contacting a dihalothiophene bearing a fullerene group and metal or metal derivative;    (3) preparing the film, comprising applying the composition to a surface;    (4) a photovoltaic device comprising the composition; and    (5) a photovoltaic device (100) comprising a first electrode (110) and a second electrode (112) separated by a polymer (120), where the polymer includes a polythiophene polymer having thienyl repeating units and a number of fullerene groups in contact with the polythiophene polymer, where at least some of the thienyl repeating units not disposed at a polymer chain terminus are covalently or ionically bonded via respective linkers to respective fullerene groups.    DESCRIPTION OF DRAWING(S) - The figure shows photovoltaic device.    Photovoltaic device (100)    First electrode (110)    Second electrode (112)    Polymer (120)    Electronic device (130)