¹Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.

²Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA.

³Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300350, P. R. China.

⁴Environment Research Institute, Shandong University, Qingdao, P. R. China.

⁵Institute of Chemistry, Henan Academy of Sciences, Zhengzhou 450046, P. R. China.

⁶Center for Molecular Systems and Organic Devices, Key Laboratory for Organic Electronics & Information Displays and Institute of Advanced Materials, Nanjing University of Posts & Telecommunications, Nanjing 210023, P. R. China.