1. Shenzhen Key Laboratory of Flexible Memory Materials and Devices
2. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province
3. College of Physics and Optoelectronic Engineering, Shenzhen University
4. Shenzhen 518060
5. P. R. China
6. Department of Physics
7. South China University of Technology
8. Guangzhou 510640
9. Southern University of Science and Technology
10. Shenzhen 518055