1. Center for Advanced Research of Energy Conversion Materials, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628, Japan, ITEC Co., Ltd., Kannanbechou 4 132, Sakai 590-0984, Japan, and Waseda University, Wasedatsurumaki-cho 513, Shinjuku-ku, Tokyo 162-0041, Japan