a
Department of Chemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
E-mail: lichengs@kth.se
b
Department of Microelectronics and Applied Physics, School of Information and Communication Technology, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
c
State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), 116024 Dalian, China