1. Department of Electronic Engineering, Dong-A University, Busan 604-714, Korea
2. Center
for Advanced Solar Photophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
3. Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791, Korea
4. Department of Chemistry, Seoul National University, Seoul 151-747, Korea