1. School of Electronic and Computer Engineering, Peking University, Shenzhen, Guangdong, China
2. TCL China Star Optoelectronics Technology Co., Ltd, Shenzhen, Guangdong, China
3. School of Advanced Materials, Peking University, Shenzhen, Guangdong, China
4. Department of Applied Physics, Heibei University of Technology, Tianjin, China