Molecular modelling and simulation for the design of molecular diodes using density functional theory

Three molecular species were modelled using TCNQ molecule as the electron acceptor and DBTTF, Tetracene and ADT molecules as the electron donor. These donor and acceptor moieties were separated by an insulating σ bridge to design suitable molecular diodes. All the molecular geometries were optimised by using the density functional theory based methods. To investigate the performance of these molecular species for the design of molecular diodes, ranging electric field was applied in two directions that are from donor to acceptor moieties and from acceptor to donor moieties. The effect of the electric field in both directions was thoroughly observed on the HOMO energy, LUMO energy, HOMO–LUMO energy gap, the spatial distribution of both frontier molecular orbitals and on the induced electric dipole moment. The outcome of the present investigation strongly suggests that charge transport is highly probable in one direction only, which means that these molecular species may be the excellent contenders for the design of molecular diodes.