1. Optoelectronics Convergence Research Center Department of Materials Science and Engineering Chonnam National University 300, Yongbong-Dong, Buk-Gu Gwangju 61186 Republic of Korea
2. Solar Energy R&D Department Green Energy Institute Mokpo 58656 Republic of Korea
3. National Physical Laboratory Council of Scientific and Industrial Research (CSIR) Dr. K.S. Krishnan Road New Delhi 110012 India