1. College of Electronic Science and Technology; Shenzhen University; Shenzhen 518060 P. R. China
2. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province; College of Optoelectronic Engineering; Shenzhen University; Shenzhen 518060 P. R. China
3. Shenzhen Key Laboratory of Laser Engineering; College of Optoelectronic Engineering; Shenzhen University; Shenzhen 518060 P. R. China
4. Department of Chemistry; South University of Science and Technology of China; No 1088, Xueyuan Road, Xili, Nanshan District Shenzhen Guangdong 518055 P. R. China
5. Institute for Advanced Study; Shenzhen University; Shenzhen 518060 P. R. China
6. Department of Materials Science and Engineering; City University of Hong Kong; Hong Kong SAR 999077 P. R. China