Fullerene-based nano-structured materials and solar cells

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The aim of this research is (1)development of structure control technique of C_<60>/a-C superlattice structures, (2)characterization of optical and electrical properties of the superlattice structures for solar cell applications, (3) basic investigation of organic solar cells using C_<60>-based nano-structures.1.a-C layer was formed by the irradiation of nitrogen radicals from rf plasma source onto C_<60> layer. We found that the character of the resulted a-C films depended on the flux of nitrogen ions.2.We observed the blue shift of light absorption edge in C_<60>/a-C superlattice structures with the thinner a-C well thickness, and suggested that the effective band gap energy could be controlled by the superlattice structure.3.The solar cells with _C_<60>/a-C superlattice structure as i-layer sandwiched between p-a-SiC and n-a-Si were fabricated. The cell showed low efficiency of 10^<-6>-10^<-5>%. To increase the cell efficiency, the conductivity control by impurity doping and the reduction of defect density in a-C layer are necessary.4.Mg-doping in C_<60> films was investigated to control the conductivity. The resistivity of Mg-doped C_<60> films deposited by the co-evaporation method reduced in 6 orders of magnitude.5.The hydrogen treatment of a-C films was investigated to reduce defect density. ESR spin defect density much depended on the hydrogen treatment time, which was necessary to optimize.6.The C_<60>/organic molecules hetero interface was investigated for organic solar cells using C_<60>-based nano-structures. It was confirmed that Copper-Phthalocyanine was deposited with standing molecular plane onto the C_<60>(111) surface.