1. Guangxi Key Laboratory of Information Material, Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, P. R. China
2. School of Physics and Electronic & Electrical Engineering, and Jiangsu Key Laboratory of Modern Measurement Technology and Intelligent Systems, Huaiyin Normal University, Huai’an 223300, P. R. China
3. School of Chemistry and Chemical Engineering & School of Physical Science and Technology, Guangxi University, Nanning 530004, P. R. China
4. Department of Materials Science and Engineering, SIT Research Laboratories, Innovative Global Program, Faculty of Engineering, Shibaura Institute of Technology, Tokyo 135-8548, Japan