pH Controlled Twist-Angle Dependent Interfacial Quantum Tunneling in Multilayer Molecular Moiré Superlattices of p-Phenylenediamine

Abstract

Molecule-based electronic circuits and device components may bring novel aspects in their functioning based on quantum phenomena that may not be attainable using conventional architecture. In order to implement such concepts development of well-defined assemblies that enable energy transfer, mass, and charge transports across several length scales is necessary. Herein it is reported that multilayer molecular moiré superlattices may provide an initial direction for attaining the abovementioned objectives. For example, multilayered 2D moiré superlattices of p-phenylenediamine showed easily identifiable twist angle-dependent electrical conductivity at each interface, as measured for the nanosheet using conductive atomic force microscopy. The absence of water molecules at the interfaces, as compared to the layered water molecules in the lattices, lowered the electron tunneling barrier and thus, increased the conductivity. Importantly, protonation and deprotonation of the superlattices in the dispersion resulted in high interfacial currents with about three orders of magnitude increase for the former. These results are further explained by density of states calculations along with carrier density and simulated scanning tunneling microscopy (STM) plots.