1. State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 P. R. China
2. Institute of Solid State Physics Hefei Institutes of Physical Science Chinese Academy of Sciences Hefei 230031 P. R. China
3. Key Laboratory of Optoelectronic Chemical Materials and Devices (Ministry of Education) Flexible Display Materials and Technology Co‐Innovation Centre of Hubei Province School of Optoelectronic Materials & Technology Jianghan University Wuhan 430056 R. R. China
4. Department of Applied Physics The Hong Kong Polytechnic University Kowloon Hong Kong 999077 P. R. China
5. Optics Valley Laboratory Hubei 430074 P. R. China
6. Research Institute of Huazhong University of Science and Technology in Shenzhen Shenzhen 518057 P. R. China