1. State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, Guangdong 510275, People's Republic of China
2. School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, Guangdong 510275, People's Republic of China
3. School of Physics, Sun Yat-sen University, Guangzhou, Guangdong 510275, People's Republic of China