Electrical Sensing of the Thermal and Light-Induced Spin Transition in Robust Contactless Spin-Crossover/Graphene Hybrid Devices

Hybrid devices based on spin-crossover (SCO)/2D heterostructures grant a highly sensitive platform to detect the spin transition in the molecular SCO component and tune the properties of the 2D material. However, the fragility of the SCO materials upon thermal treatment, light irradiation, or contact with surfaces and the methodologies used for their processing have limited their applicability. Here, an easily processable and robust SCO/2D hybrid device with outstanding performance based on the sublimable SCO [Fe(Pyrz)(2)] molecule deposited over chemical vapor deposition (CVD) graphene is reported, which is fully compatible with electronics industry protocols. Thus, a novel methodology based on growing an elusive polymorph of [Fe(Pyrz)(2)] (tetragonal phase) over graphene is developed that allows a fast and effective light-induced spin transition in the devices (approximate to 50% yield in 5 min) to be detected electrically. Such performance can be enhanced even more when a flexible polymeric layer of poly(methyl methacrylate) is inserted in between the two active components in a contactless configuration, reaching a approximate to 100% yield in 5 min.

Automated summary

Hybrid devices based on spin-crossover/2D heterostructures provide a sensitive platform to detect spin transitions and tune the properties of 2D materials. However, the fragility of spin-crossover materials and the limitations of processing methods have restricted their applicability. This study presents an easily processable and robust hybrid device, where sublimable spin-crossover [Fe(Pyrz)(2)] molecules are deposited on chemical vapor deposition graphene. By growing an elusive polymorph of [Fe(Pyrz)(2)] on graphene, a fast and effective light-induced spin transition in the devices can be electrically detected.