Photovoltaic devices based on nanocrystalline TiO/sub 2/ and a fluorene-thiophene copolymer

We report studies of charge recombination and photovoltaic device performance in structures consisting of a fluorene-bithiophene co-polymer and nanocrystalline TiO/sub 2/. Efficient photoinduced charge transfer is observed using a TiO/sub 2/ film of high interfacial area while charge recombination is remarkably slow (/spl sim/ms). The influences of thickness, surface morphology, top contact material, light intensity and ionization potential of the polymer are studied. Quantum efficiencies of over 11% and monochromatic power conversion efficiencies of around 1% are achieved.