1. CAS Key Laboratory of Renewable Energy, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
2. School of Physical and Electronic Sciences, Chuxiong Normal University, Chuxiong 675099, P. R. China
3. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
4. Energy Research Institute, Academy of Macroeconomics, National Development and Reform Commission, Beijing 100038, P. R. China