Electron transport in fullerene-terminated tetracene molecular junction: a DFT study

Abstract

By applying non-equilibrium green’s function (NEGF) formalism combined with density functional theory (DFT), this study aims to investigate and compare the electron transport properties of tetracene molecules anchored with C₂₀, C₂₄ and C₂₈ fullerene molecules. The results indicate that tetracene molecule exhibits metallic behaviour with C₂₀ anchors, whereas C₂₄ and C₂₈ fullerenes, respectively, show semi-metallic and non-metallic nature. Various attributes such as transmission spectrum, density of states (DOS), molecular projected self-consistent Hamiltonian (MPSH) eigen states, conductance and current characteristics conclude that shifting of the molecular orbitals with variations in the bias voltage determines the current spectrum. The nonlinearity in the I–V curve and troughs in the G–V curve are attributed to the transitions seen in the active molecular orbitals, resulting in a variation in the HOMO–LUMO gap. Further, a multifunctional behaviour showing a clear negative differential resistance region with peak-to-valley current ratio of 1.70 and rectifying performance with a rectification ratio of 1.45 in the case of C₂₀–tetracene–C₂₀ molecular junction is observed. These results will pave a new road map for developing versatile molecular devices with targeted properties.