1. State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
2. School of Physics and Electronics, Qiannan Normal University for Nationalities, Duyun 558000, China
3. School of Physics, Sun Yat-sen University, Guangzhou 510275, China
4. School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China