1. Hunan Provincial Key laboratory of Thin Film Materials and Devices School of Material Sciences and Engineering Xiangtan University Xiangtan 411105 China
2. Hunan Key Laboratory for Micro-Nano Energy Materials and Devices School of Physics and Optoelectronics Xiangtan University Hunan 411105 China
3. School of Material Sciences and Engineering Xiangtan University Xiangtan 411105 China