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Published on: August 2, 2019
Gated off-site radical injection: Bidirectional conductance modulation in single-molecule junctions
Hanjun Zhang1, Lichuan Chen2,3, Xiaodong Liu1
1School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 611731, P. R. China.
Abstract:
Uncovering the effects of radical injection into responsive organic molecules is a long-sought goal, and the single-molecule junctions provide a unique way to investigate molecular conductance evolution during the radical injection. We can modulate the main channel conductance by using electronic injection from off-site neutral radicals acting as gating terminals. Two families of cyclopentadienone derivatives were synthesized, featuring the inter-pyridyl main conductance channel and the inter-radical paths that are linear (FCF) or cross conjugated (PCP). Using a scanning tunneling microscope break junction technique, we find that the injection of mono- and diradicals in the PCP system unexpectedly decreases the conductance regarding the closed-shell analog, while that of FCF systems increases. Through-bond and through-space conductance mechanisms are found in the FCF and PCP series, respectively, and jointly modulate the overall charge transmission. This off-site injection concept offers a promising approach for developing molecular devices by manipulating electrical conductance in single-molecule junctions.
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