Electronic Switching in Self-Assembled Monolayers of Ladder-Type Molecules

The development of large-area two-dimensional (2D) molecular devices has garnered significant attention due to their potential applications in next-generation electronics. Ladder-type molecules, with their shape-persistent π-conjugated backbones and unique electronic properties, have emerged as promising candidates for controlling the conductance and electronic switching behavior in these devices. In this work, we characterize the electronic properties of ladder-type molecules in large-area self-assembled monolayers in 2D molecular devices. A soft-contact liquid metal electrode (eutectic gallium indium, EGaIn) is used to determine the current-voltage response of self-assembled monolayers of ladder-type molecules driven up to an applied bias of 2.5 V. Our results show a robust switching behavior in monolayer current in forward and backward voltage scans, which is hypothesized to arise due to redox events induced at high bias. These results extend beyond our prior work in studying nanogap-independent conductance behavior in redox active molecules using the scanning tunneling microscope break junction (STM-BJ) technique. Overall, this work paves the way for the rational design of 2D molecular systems using ladder-type molecules, offering new opportunities for the development of advanced electronic devices with improved functionality and miniaturization.