1. Key Lab of Photovoltaic and Energy Conservation Materials, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, PR China
2. University of Science and Technology of China, Hefei 230026, PR China
3. Anhui University, Hefei 230601, PR China
4. New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8577, Japan
5. Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu India
6. School of Physics, Suranaree University of Technology, 111 University Avenue Muang, Nakhon Ratchasima 30000, Thailand