Molecular rectifier based on π-π Stacked charge transfer complex

Electron transport through π-π stacked materials has been studied theoretically and experimentally so far with versatile applications in mind. In this paper a novel π-π stacked molecular rectifier is proposed. Electron transport properties through cyclophane-type quinhydrone are investigated by using nonequilibrium Green's function method combined with density functional theory. The investigated molecule has a quinhydrone structure comprised of π-π stacked donor (hydroquinone) and acceptor (benzoquinone) pair due to the in-phase orbital interaction between the HOMO of hydroquinone and the LUMO of benzoquinone. A computed current-voltage curve shows rectifying behavior in the direction perpendicular to the ring plane. The maximum value of rectification ratio of 2.37 is obtained at 0.8 V. In this system the LUMO level plays a key role, and asymmetrical evolution of the LUMO level for positive and negative biases leads to the rectifying behavior. The present study is a basic step for further functionalization of a molecular rectifier based on transannular electron transport. The understanding of insight into the electron transport through a π-π stacked system will provide motivation for design of future molecular devices.