1. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Key Laboratory for the Green Preparation and Application of Functional Materials, Ministry of Education, Hubei Key Laboratory of Polymer Materials, School of Materials Science and Engineering, Hubei University, Wuhan 430062, P. R. China
2. Hubei Key Laboratory of Ferro & Piezoelectric Materials and Devices, School of Microelectronics, Hubei University, Wuhan 430062, P. R. China
3. Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China