1. Key Laboratory of Luminescence and Optical Information Beijing Jiaotong University Ministry of Education Beijing 100044 P. R. China
2. Department of Chemical and Biomolecular Engineering Tandon School of Engineering New York University New York NY 11201 USA
3. Institute of Optoelectronic Technology Beijing Jiaotong University Beijing 100044 P. R. China
4. Research Institute for Green Energy Convergence Technology Gyeongsang National University Jinju South Gyeongsang Province 52828 Republic of Korea
5. Research Institute for Solar and Sustainable Energies Gwangju Institute of Science and Technology Gwangju 61005 Republic of Korea