Rational Design of Reversible Molecular Photoswitches Based on Diarylethene Molecules

Reversible conductance photoswitching behaviors of single diarylethene molecule have garnered increasing interest in recent studies. It was revealed that the molecule–electrode coupling strength plays a critical role in the realization of bidirectional conductance switching. Here, we report first-principles calculations of molecular devices based on photoswitching diarylethene molecules of two stable isomers, i.e., the ring-open form and the ring-closed form. A method of nonequilibrium Green’s function combined with density functional theory is used to calculate the electronic transport properties and the switching mechanism of the devices. The results point to a large diversity in the electrical conductivity, and the switching behavior depends essentially on the electronic structure of the molecule itself, regardless of the electrodes used in the devices, which is consistent with previous studies. Importantly, the on–off current ratio of the devices is predicted to be as large as 103 and negative differential resistance effect is observed in devices with graphene electrodes. These findings are helpful for the rational design of molecular photoswitches based on diarylethene and similar organic molecules.