1. School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, People’s Republic of China
2. Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan 411105, People’s Republic of China
3. College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, People’s Republic of China