First principle investigations on transport properties in porphyrin, hexaphyrin, and hexathia[26π]annulene molecular junction devices

Abstract

The quantum charge transport calculations at metal–molecule–metal junctions lead to various electronic properties suitable in the field of miniaturization. Finite bias-dependent conductivity is calculated through porphyrin, hexaphyrin, and hexathia[26π]annulene molecular junction devices connected to the metallic or semiconducting electrode using non-equilibrium Green's function technique based on the density functional theory method. The (I−V) characteristic curves calculated for various donor–insulator–acceptor (D–σ–A) devices show a Ohmic, diode, or rectifier-like nature depending on the donor acceptor substitution effect in the above molecules connected to the electrode. The rectification ratio R (I+/I− or I−/I+) calculated for such devices varies from 2 to 70, and maximum R is calculated for the D–A-substituted porphyrin molecular junction. The I−V characteristics, rectification, and negative differential resistance effect found in such devices are well analyzed by projected density of states and molecular-projected self-consistent Hamiltonian eigenstate, local density of state calculations. Molecular conductivity calculations in D–σ–A devices using porphyrin, hexaphyrin, and hexathia[26π]annulene show promise in the field of molecular electronics and memory storage devices.