* Corresponding authors

^a Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
E-mail: zhongyuwu@iccas.ac.cn
Fax: +86-10-62559373
Tel: +86-10-62652950

^b Key Laboratory for Renewable Energy (CAS), Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condense Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
E-mail: qbmeng@iphy.ac.cn
Fax: +86-10-82649242
Tel: +86-10-82649242

^c School of Physical Sciences, College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China