Contactless Spin Switch Sensing by Chemo‐Electric Gating of Graphene. Issue 10 (3rd February 2020)

• Record Type: Journal Article
• Authors: van Geest, Erik P.; Shakouri, Khosrow; Fu, Wangyang; Robert, Vincent; Tudor, Viorica; Bonnet, Sylvestre; Schneider, Grégory F.
• Is Part Of: Advanced materials. Volume 32:Issue 10(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-03
• Subjects: chemo‐electric gating -- contactless sensing -- graphene -- molecular materials -- spin crossover; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201903575
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Direct electrical probing of molecular materials is often impaired by their insulating nature. Here, graphene is interfaced with single crystals of a molecular spin crossover complex, [Fe(bapbpy)(NCS)2 ], to electrically detect phase transitions in the molecular crystal through the variation of graphene resistance. Contactless sensing is achieved by separating the crystal from graphene with an insulating polymer spacer. Next to mechanical effects, which influence the conductivity of the graphene sheet but can be minimized by using a thicker spacer, a Dirac point shift in graphene is observed experimentally upon spin crossover. As confirmed by computational modeling, this Dirac point shift is due to the phase‐dependent electrostatic potential generated by the crystal inside the graphene sheet. This effect, named as chemo‐electric gating, suggests that molecular materials may serve as substrates for designing graphene‐based electronic devices. Chemo‐electric gating, thus, opens up new possibilities to electrically probe chemical and physical processes in molecular materials in a contactless fashion, from a large distance, which can enhance their use in technological applications, for example, as sensors. Abstract : With graphene field‐effect transistors, phase transitions in spin‐crossover crystals can be electrically sensed in a contactless fashion by a new sensing mechanism, called chemo‐electric gating: graphene responds to the changing electrostatic potential of the crystal as the molecules switch their spin state. This study showcases how insulating molecular materials, using chemo‐electric gating, can be integrated in electronic devices.