High-Conductance Conformers in Histograms of Single-Molecule Current–Voltage Characteristics

Abstract

Understanding charge transport across single molecular junctions is essential for the rational design and optimization of molecular device components. However, the correlation between calculated and experimental transport properties of single molecules probed by current–voltage (I–V) characteristics is often uncertain. Part of the challenge is that molecular conductance is sensitive to several factors that are difficult to control, including molecular orientation, conformation, aggregation, and chemical stability. Other challenges include the limitations of computational methodologies. Here, we implement the Σ-Extended Huckel (EH) nonequilibrium Green’s function (NEGF) method to analyze the histogram of I–V curves of 4,4′-diaminostilbene probed by break-junction experiments. We elucidate the nature of the molecular conformations with a widespread distribution of I–V curves, typically probed under experimental conditions. We find maximum conductance for molecules that are not at the minimum energy configur...