Multilayer Molecular Moiré Superlattices of para Phenylene Diamine Exhibit Angle-dependent and pH Controlled High Interfacial Electrical Conductivity Through Tunneling

Here we report the formation of multilayered molecular moiré superlattices of para phenylene diamine that showed a ten-fold increase in the interfacial conductivity as compared to its mono-lattice counterpart. The increase in the interfacial current for moiré superlattices was due to the decrease in tunneling barrier and length at the interface of superlattice owing to the absence of intervening water molecules the presence of which increased the barrier in the 2D lattice. Fast Fourier transform was used to decipher the interfacial current from the conductive atomic force microscopy measurements on the multilayered superlattices. A monotonous decrease in the interfacial current was observed as the twist angles increased for the same superlattice. The twist angle was strongly correlated with the number of hydrogen bonds at the interface and thus a twist dependent variation in interfacial current was observed. Furthermore, a significant increase in the interfacial current upon protonation or deprotonation of the moiré superlattices was observed due to the increase in number of hydrogen bonds at the multi-lattice interfaces.