1. MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering; Department of Chemistry; Tsinghua University; Beijing 100084 P. R. China
2. Key Laboratory of Organic Solids; Beijing National Laboratory for Molecular Science (BNLMS); Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
3. Collaborative Innovation Center of Chemistry for Energy Materials; Xiamen University; Xiamen 351005 P. R. China