1. Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
2. Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
3. Center of Super-Diamond and Advanced Film (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, China