1. School of Applied Physics and Materials, Wuyi University, Jiangmen 529020, Guangdong Province, P. R. China
2. Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
3. Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China