Nearfield trapping increases lifetime of single-molecule junction by one order of magnitude

Albert C Aragonès,Katrin F Domke

doi:10.1016/j.xcrp.2021.100389

Albert C Aragonès, Katrin F Domke

Open Access

https://doi.org/10.1016/j.xcrp.2021.100389

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Abstract

Progress in molecular electronics (ME) is largely based on improved understanding of the properties of single molecules (SMs) trapped for seconds or longer to enable their detailed characterization. We present a plasmon-supported break-junction (PBJ) platform to significantly increase the lifetime of SM junctions of 1,4-benzenedithiol (BDT) without the need for chemical modification of molecule or electrode. Moderate far-field power densities of ca. 11 mW/μm2 lead to a >10-fold increase in minimum lifetime compared with laser-OFF conditions. The nearfield trapping efficiency is twice as large for bridge-site contact compared with hollow-site geometry, which can be attributed to the difference in polarizability. Current measurements and tip-enhanced Raman spectra confirm that native structure and contact geometry of BDT are preserved during the PBJ experiment. By providing a non-invasive pathway to increase short lifetimes of SM junctions, PBJ is a valuable approach for ME, paving the way for improved SM sensing and recognition platforms.

Highlights

The field of molecular electronics (ME) aims at miniaturising electronic devices and surpassing the space limitation of conventional silicon circuit integration.[1]
We present a plasmonsupported break-junction (PBJ) platform to significantly increase the lifetime of single molecules (SM) junctions of 1,4-benzendithiol (BDT) without the need for chemical modification of molecule or electrode
We demonstrate that nearfield trapping provides an straightforward way to increase molecular junction robustness without the need for chemical modification of target molecule and/or electrode and in this way opens up new possibilities for single-molecule characterization during prolonged time scales of >1 s without compromising the chemical integrity of the junction

Summary

Introduction

The field of molecular electronics (ME) aims at miniaturising electronic devices and surpassing the space limitation of conventional silicon circuit integration.[1]. From the PBJ results in correlation with solid/liquid TER spectra, we find that the presence of a nearfield gradient in the order of 6.3 x 107 V/m leads to a significant increase of τ of the single-molecule junction by up to one order of magnitude.

Results

Conclusion