1. Center for Photovoltaics Solar Cell, Shenzhen Institutes of Advance Integration Technology, Chinese Academy of Sciences, Shenzhen, 518055, People’s Republic of China, Department of Physics, Xuzhou Normal University, Xuzhou, 221116, People’s Republic of China, Department of Physics, Binzhou Medical University, Yantai, 264003, People’s Republic of China, and Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, People’s Republic of China