Remote-Controllable Interfacial Electron Tunneling at Heterogeneous Molecular Junctions via Tip-Induced Optoelectrical Engineering.

Molecular electronics enables functional electronic behavior via single molecules or molecular self-assembled monolayers, providing versatile opportunities for hybrid molecular-scale electronic devices. Although various molecular junction structures are constructed to investigate charge transfer dynamics, significant challenges remain in terms of interfacial charging effects and far-field background signals, which dominantly block the optoelectrical observation of interfacial charge transfer dynamics. Here, tip-induced optoelectrical engineering is presented that synergistically correlates photo-induced force microscopy and Kelvin probe force microscopy to remotely control and probe the interfacial charge transfer dynamics with sub-10 nm spatial resolution. Based on this approach, the optoelectrical origin of metal-molecule interfaces is clearly revealed by the nanoscale heterogeneity of the tip-sample interaction and optoelectrical reactivity, which theoretically aligned with density functional theory calculations. For a practical device-scale demonstration of tip-induced optoelectrical engineering, interfacial tunneling is remotely controlled at a 4-inch wafer-scale metal-insulator-metal capacitor, facilitating a 5.211-fold current amplification with the tip-induced electrical field. In conclusion, tip-induced optoelectrical engineering provides a novel strategy to comprehensively understand interfacial charge transfer dynamics and a non-destructive tunneling control platform that enables real-time and real-space investigation of ultrathin hybrid molecular systems.