1. Zhejiang Engineering Research Center for Fabrication and Application of Advanced Photovoltaic Materials, School of Materials Science and Engineering, NingboTech University, Ningbo, 315100, China
2. School of New Energy Science and Engineering, Xinyu University, Xinyu, 338004, China
3. National Photovoltaic Engineering Research Center, LDK Solar Co., Ltd., Xinyu 338032, China