1. Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
2. New and Renewable Energy Research Center, Ewha Womans University, Seoul 03760, Republic of Korea
3. Photovoltaic Laboratory, Korea Institute of Energy Research (KIER), Daejeon 34129, Republic of Korea
4. Department of Energy Engineering, Korea Institute of Energy Technology, Naju 58330, Republic of Korea