1. Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Analytical and Testing Center, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China
2. School of Materials Science and Engineering, Engineering Research Center of Electronic Information Materials and Devices, Ministry of Education, Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, 1st Jinji Road, Guilin, 541004, China