Connectivity-Dependent Attenuation Factor in Nanographene-Based Molecular Wires

Abstract

Designing molecular nanowires with high electrical conductance that facilitate efficient charge transport over long distances is highly desirable for future molecular-scale circuitry. However, most molecular wires act as tunnel barriers, and their electrical conductance decays exponentially with increasing length. Only recently have a few studies shown increasing conductance with length. In this study, we identify a new class of molecular wires that exhibit both an increase and a decrease in room-temperature conductance with length (a dual attenuation factor), depending on their connection points to the electrodes. We show that this dual attenuation factor is an inherent property of these graphene-like nanowires, and its demonstration depends on the constructive quantum interference pattern for different connectivities to the electrodes. This is significant because a given nanographene molecular wire can show both negative and positive attenuation factors. This enables the systematic design of connectivity-dependent high/low-conductance molecular wires for future molecular-scale circuitry.