1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China
2. State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China
3. Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
4. International Research Centre for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China
5. Micro-Optoelectronic Systems Laboratories, Xi’an Technological University, Xi’an 710032, Shaanxi, China
6. Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, P. R. China