1. Thin Film Materials Laboratory, Advanced Materials Division, Korea Research Institute of Chemical Technology, Yuseong, P.O. Box 107, Daejeon 305-600, Korea, Department of Materials Science and Engineering, Hongik University, 72-1 Sangsu-dong, Mapo-gu, Seoul 121-791, Korea, and Department of Chemistry, Chungbuk National University, San 48, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Korea