Sulfur atoms can be easily photooxidized in ambient conditions, and this can make it difficult to achieve stable and robust photoswitching of molecules in thiol-based self-assembled monolayers. This presentation describes fabrication of N-heterocyclic carbene (NHC) based self-assembled monolayers (SAMs) and the light-dependence of tunneling current density in their junctions. Diarylethene-NHC molecules are chemisorbed on template-stripped gold substrates, and the resulting monolayers are used to form large-area junctions with a soft top-electrode comprising eutectic gallium-indium alloy (EGaIn) covered with a conductive native Ga2O3 layer. By irradiating ultraviolet and visible lights onto the SAM-bound gold electrode, the closed and open ring isomers of diarylethene are reversibly obtained. Such a reversible and in situ photoswitching in the solid-state junction is straightforwardly translated into about one order of magnitude difference in tunneling current density between the two isomers. Interestingly, this bistable feature was maintained after SAMs were exposed to harsh conditions such as acidic/basic solutions, heating at 100 oC, and long-term aging in air. Our study demonstrates that the use of NHC carbene as an anchoring group can lead to robust and reproducible bistable SAMs for photoswitch application.

Photoswitching tunnel junctions formed with N-Heterocyclic carbene (NHC)-based self-assembled monolayer

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.