1. School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, China
2. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
3. School of Physics and Electronics, Hunan University, Changsha 410082, China