Abstract

C₆₀-based bulk heterojunction solar cells were fabricated, and the electronic and optical properties were investigated. C₆₀ were used as n-type semiconductors, and copper oxides, porphyrin, phthalocyanines, CuInS₂ and nano-diamond were used as p-type semiconductors. An effect of exciton-diffusion blocking layer of perylene derivative on the solar cells between active layer and metal layer was also investigated. Optimized structures with the exciton-diffusion blocking layer improved conversion efficiencies. Electronic structures of the molecules were investigated by molecular orbital calculation, and energy levels of the solar cells were discussed. Nanostructures of the solar cells were investigated by transmission electron microscopy, electron diffraction and X-ray diffraction, which indicated formation of mixed nanocrystals.