Structural and electronic switching of a single crystal 2D metal-organic framework prepared by chemical vapor deposition.

Claire, F James; Solomos, Marina A; Kim, Jungkil; Wang, Gaoqiang; Siegler, Maxime A; Crommie, Michael F; Kempa, Thomas J · Nat Commun · 2020

basic_science · Level V

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Abstract

The incorporation of metal-organic frameworks into advanced devices remains a desirable goal, but progress is hindered by difficulties in preparing large crystalline metal-organic framework films with suitable electronic performance. We demonstrate the direct growth of large-area, high quality, and phase pure single metal-organic framework crystals through chemical vapor deposition of a dimolybdenum paddlewheel precursor, Mo<sub>2</sub>(INA)<sub>4</sub>. These exceptionally uniform, high quality crystals cover areas up to 8600 µm<sup>2</sup> and can be grown down to thicknesses of 30 nm. Moreover, scanning tunneling microscopy indicates that the Mo<sub>2</sub>(INA)<sub>4</sub> clusters assemble into a two-dimensional, single-layer framework. Devices are readily fabricated from single vapor-phase grown crystals and exhibit reversible 8-fold changes in conductivity upon illumination at modest powers. Moreover, we identify vapor-induced single crystal transitions that are reversible and responsible for 30-fold changes in conductivity of the metal-organic framework as monitored by in situ device measurements. Gas-phase methods, including chemical vapor deposition, show broader promise for the preparation of high-quality molecular frameworks, and may enable their integration into devices, including detectors and actuators.