Side-group chemical gating via reversible optical and electric control in a single molecule transistor

Linan Meng,Cheng Shen,Jinying Wang,Hong Guo,Bo Gui,Junjie Shi,Cheng Wang,Chen Hu,Xuefeng Guo,Sheng Meng,Na Xin,Guangyu Zhang

doi:10.1038/s41467-019-09120-1

Abstract

By taking advantage of large changes in geometric and electronic structure during the reversible trans–cis isomerisation, azobenzene derivatives have been widely studied for potential applications in information processing and digital storage devices. Here we report an unusual discovery of unambiguous conductance switching upon light and electric field-induced isomerisation of azobenzene in a robust single-molecule electronic device for the first time. Both experimental and theoretical data consistently demonstrate that the azobenzene sidegroup serves as a viable chemical gate controlled by electric field, which efficiently modulates the energy difference of trans and cis forms as well as the energy barrier of isomerisation. In conjunction with photoinduced switching at low biases, these results afford a chemically-gateable, fully-reversible, two-mode, single-molecule transistor, offering a fresh perspective for creating future multifunctional single-molecule optoelectronic devices in a practical way.

Highlights

By taking advantage of large changes in geometric and electronic structure during the reversible trans–cis isomerisation, azobenzene derivatives have been widely studied for potential applications in information processing and digital storage devices
We demonstrate a chemically-gated, fullyreversible, two-mode, single-molecule transistor based on a robust graphene-molecule-graphene single-molecule junction (GMG-SMJ) formed by covalently sandwiching an azobenzene unit, which is immobilised at the side position of a terphenyl aromatic chain, between graphene point contacts (Fig. 1a)
By using nanogapped graphene point contacts fabricated through a dashline lithographic (DLL) method described elsewhere[41], we covalently incorporated individual TTDA molecules into graphene electrodes that have been prefunctionalised by p-phenylenediamine through amide bonds to form single-molecule junctions (Fig. 1, Supplementary Figures 1–3)

Summary

Introduction

By taking advantage of large changes in geometric and electronic structure during the reversible trans–cis isomerisation, azobenzene derivatives have been widely studied for potential applications in information processing and digital storage devices. We report an unusual discovery of unambiguous conductance switching upon light and electric fieldinduced isomerisation of azobenzene in a robust single-molecule electronic device for the first time Both experimental and theoretical data consistently demonstrate that the azobenzene sidegroup serves as a viable chemical gate controlled by electric field, which efficiently modulates the energy difference of trans and cis forms as well as the energy barrier of isomerisation. The two isomers differentiate in the end-to-end distance30—the distance between the two carbon atoms in position 4 of the phenyl rings is ~9.0 and ~5.5 Å in trans form and cis form, respectively These properties make azobenzene units popular in many systems, such as polymers[31], liquid crystals[32], and nanoparticles[33], which have produced various novel applications including digital storage[34] and on-command drug delivery[35]. A crucial discovery is that both quantum mechanical calculations and experimental data reveal a Optical/electrical stimuli

Methods

Results

Conclusion