1. Guangxi Key Laboratory of Information Materials & Guangxi Collaborative Innovation Center for Structure and Properties for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, P. R. China
2. School of Electronic Engineering and Automation, Guilin University of Electronic Technology, Guilin 541004, P. R. China
3. Guilin Electrical Equipment Scientific Research Institute Co. Ltd, Guilin 541004, P. R. China
4. School of Chemical Engineering, Changsha University of Science and Technology, Changsha 410076, P. R. China
5. Institute of Science and Technology for New Energy, Xi'an Technological University, Xi'an 710021, P. R. China
6. Guangxi Institute of Botany, Chinese Academy of Sciences, Guilin 541004, P. R. China