In this research, the electronic transport of Salicylidene Ethylamine (SEA) with and without substituents by nonequilibrium green’s function (NEGF) joined with density functional theory (DFT) were studied. UV light can convert these molecular optical switches from enol-imine tautomer to keto-amine tautomer. For this purpose, intramolecular hydrogen bonding (IHB) of SEA and its halogen derivatives (–Cl and –Br) have been studied at the DFT-B3LYP/6-311++G** theoretical level. IHB of target molecules is the most straight resonance-assisted hydrogen bond system in symmetric O–H⋯N and O⋯H–N classes. We obtained some items, including different in structural bond lengths and bond angles, H-bond energies, the effect of electrode surface (Pt, Au, and Ag) and adsorption attachment sites (bridge, hollow, and top), I–V physical appearance, on/off ratios, HOMO– LUMO gaps, and transmittance spectra. The results presented that as the molecular optical switches converted from enol-imine form to keto-amine form (enol-imine → keto-amine), conductivity changes from off mode (high resistance) to on mode (low resistance). The best switching performance obtained in the silver surface at the hollow site. The on/off ratios clarified that the SEA molecular optical switch is suitable at high voltages. The NEGF joined with DFT calculations showed that substituents –Br and –Cl at X position decreased the switching efficiency.

Keywords