Memristive Switches in Rigid Conjugated Single-Molecule Junctions

Abstract

Voltage-driven memristive switching has been reported in molecular junctions, yet its microscopic origin often remains elusive. Here, we study three rigid OPE-like derivatives that lack an obvious internal switching pathway. Using mechanically controlled break junctions (MCBJs), we observe nonvolatile, bistable, hysteretic I–V characteristics at cryogenic temperatures. We introduce a quantitative analysis workflow that classifies memristive I–Vs, clusters the two conductance states, and extracts switching features and stability metrics from repeated measurements at fixed displacement. While all molecules exhibit memristive behavior, stability and hysteresis reproducibility depend strongly on anchoring and connectivity: the linear biphenyl backbone with thiolate (SAc) anchoring shows the most reproducible, predominantly field-driven hysteresis, whereas the meta-phenyl variant with thioether (SMe) anchoring is dominated by stochastic, current-driven events. The resulting conductance statistics point to an extrinsic, mechanically mediated origin involving contact rearrangements, multimolecule transport, blinking (open–closed) contacts, injection-point shifts, and π–π-stacking dimerization.