1. National Center for International Research on Photoelectric and Energy Materials, Yunnan Key Laboratory for Micro/Nano Materials and Technology, School of Materials and Energy, Yunnan University 1 , Kunming 650091, People’s Republic of China
2. Kunming Institute of Physics 2 , Kunming 650223, People’s Republic of China
3. Faculty of Materials Science and Engineering, Kunming University of Science and Technology 3 , Kunming 650093, People’s Republic of China