Stable molecular switches

Many single-molecule current switches have been reported, but most show poor stability because of weak contacts to metal electrodes. Jia et al. covalently bonded a diarylethene molecule to graphene electrodes and achieved stable photoswitching at room temperature (see the Perspective by Frisbie). The incorporation of short bridging alkyl chains between the molecule and graphene decoupled their pielectron systems and allowed fast conversion of the open and closed ring states.

Abstract

Through molecular engineering, single diarylethenes were covalently sandwiched between graphene electrodes to form stable molecular conduction junctions. Our experimental and theoretical studies of these junctions consistently show and interpret reversible conductance photoswitching at room temperature and stochastic switching between different conductive states at low temperature at a single-molecule level. We demonstrate a fully reversible, two-mode, single-molecule electrical switch with unprecedented levels of accuracy (on/off ratio of ~100), stability (over a year), and reproducibility (46 devices with more than 100 cycles for photoswitching and ~105 to 106 cycles for stochastic switching).