Hybrid solar cells based on dye-sensitized nanoporous TiO2 electrodes and conjugated polymers as hole transport materials

Abstract Solid state dye-sensitized photovoltaic solar cells were fabricated using a three-layer concept. The hybrid devices consist of a transparent inorganic nanocrystalline titanium dioxide (nc-TiO 2 ) layer with a thickness of 2 μm as electron acceptor and for electron transport. A surface-adsorbed RuL2(NCS)2:2 TBA dye complex (where L=2,2′-bipyridyl-4,4′-dicarboxylic acid; TBA=tetrabutylammonium) is utilized for light absorption and electron injection to the conduction band of TiO 2 . For the transport of holes to the back contact electrode conjugated polymers are used, either a poly(3-octylthiophene) (P3OT), or a low band-gap thiophene–isothianaphthene-based copolymer (PDTI). These devices exhibit an overall energy conversion efficiency of approximately 0.16% under simulated solar irradiation (80 mW/cm 2 ). Furthermore, we have investigated the surface network morphology of these film layers by atomic microscope (AFM) exploring strategies to improve the efficiency.