Nearfield Trapping Increases Lifetime of Single-Molecule Junction by One Order of Magnitude

Abstract

Progress in molecular electronics (ME) is largely based on improved understanding of the properties of single molecules (SM) 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-benzendithiol (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 to laser-OFF conditions. The nearfield trapping efficiency is twice as large for bridge-site contact compared to 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.