Kazuya Fujimoto

Fabrication and Characterization of ZnO/Cu2O Solar Cells Prepared by Electrodeposition

Cuprous oxide (Cu2O)-based solar cells containing zinc oxide (ZnO) were fabricated on F-doped tin oxide (FTO) by electrodeposition. Cu2O layers were deposited from a pH-adjusted electrolyte consisting of LiOH, NaOH or KOH. A photovoltaic device based on a FTO/ZnO/Cu2O/Au heterojunction structure was prepared using LiOH, and it gave a power conversion efficiency of 1.43% under air mass 1.5 illumination.

Microstructures and photovoltaic properties of C60 based solar cells with copper oxides, CuInS2, phthalocyanines, porphyrin, PVK, nanodiamond, germanium and exciton diffusion blocking layers

Abstract Organic solar cells have a potential for use in lightweight, flexible, inexpensive and large scale solar cells. However, significant improvements of photovoltaic efficiencies are mandatory for use in future solar power plants. One of the improvements is donor–acceptor proximity in the devices, which are called bulk heterojunction solar cells. Bulk heterojunction is an efficient method to generate free charge carriers, and the charge transfer is possible at the semiconductor interface. The purpose of the present work is to fabricate and characterise C60 based solar cells with copper oxides, CuInS2, phthalocyanines, porphyrin, poly-vinylcarbazole, nanodiamond, germanium and exciton diffusion blocking layers. In the present work, C60 and fullerenol [C60(OH)10–12] were used for n-type semiconductors, and metal copper oxides, metal phthalocyanine derivative, porphyrin and poly-vinylcarbazole were used for p-type semiconductors. In addition, nanodiamond and germanium based molecules were added into the active layers of the solar cells. The novel aspect of the research is to investigate the relation between properties and microstructures of the solar cells using transmission electron microscopy, X-ray diffraction and electronic structure calculation. The impact of the research concerns the study of organic solar cells by means of microstructural analysis, property measurements and theoretical calculations.

Fabrication and characterization of copper oxide-zinc oxide solar cells prepared by electrodeposition

Copper oxide-based heterojunction solar cells were fabricated by electrodeposition, and the electronic and optical properties were investigated. ZnO was used as an n-type semiconductor, and copper oxides were used as p-type semiconductors. A photovoltaic device based on an FTO/ZnO/Cu2O heterojunction structure provided short-circuit current density of 2.7 mAcm−2 and open circuit voltage of 0.28 V under an air mass 1.5 illumination. Microstructures of the solar cells were investigated by scanning electron microscope and X-ray diffraction, which indicated formation of copper oxides and ZnO. Energy levels of the solar cells were discussed.

Microstructures and photovoltaic properties of fullerene- based organic-inorganic hybrid solar cells

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, CuInS2 and diamond were used as p-type semiconductors. 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.

Fabrication and photovoltaic properties of ZnO nanorods/perovskite solar cells

ZnO nanorods/perovskite solar cells with different lengths of ZnO nanorods were fabricated. The ZnO nanorods were prepared by chemical bath deposition and directly confirmed to be hexagon-shaped nanorods. The lengths of the ZnO nanorads were controlled by deposition condition of ZnO seed layer. Photovoltaic properties of the ZnO nanorods/CH3NH3PbI3 solar cells were investigated by measuring current density-voltage characteristics and incident photon to current conversion efficiency. The highest conversion efficiency was obtained in ZnO nanorods/CH3NH3PbI3 with the longest ZnO nanorods.