Diarylethenes are photosensitive φ-conjugated molecules, being of great promise in potential applications to various molecular devices. Although the switching properties of diarylethenes have been widely investigated experimentally and theoretically, little is known about their rectifying diode-like behavior. In this study, electron-transport properties of asymmetric diarylethenes incorporating two different heterocyclic five-membered rings with opposite electronic demands are investigated with the nonequilibrium Green function combined with density functional theory. The aim of this study is to derive the effect of the heteroatomic defects on not only switching but also rectifying characteristics of the asymmetric diarylethenes. Obtained results show that a silicon atom involved in the diarylethenes plays an important role in the current rectifying as well as switching performance. It is found that maximum rectification ratios of the asymmetric diarylethenes increase linearly with an increase in electronegativity difference between the asymmetrically arranged heteroatoms. The silicon- and oxygen-containing asymmetric diarylethene is suggested to be a good potential candidate for a novel molecular electronic device combining a switch and a diode.
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