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

Abstract

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 (≈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 ≈100% yield in 5 min.

High-Sensitivity Microthermometry Method Based on Vacuum-Deposited Thin Films Exhibiting Gradual Spin Crossover above Room Temperature

“…This work extends the limited portfolio of SCO compounds for demanding microthermometry applications and highlights once again the technological interest of this family of stimuli-responsive molecular materials. Yet, it remains crucial to develop further high-quality thin films and other micro–nano objects of SCO materials displaying robust, near-room-temperature SCO combined with the desired (optical, electrical, and mechanical) functionalities. − …”

An iron(II) complex shows bistable spin-state switching characteristic with T1/2 centred at room temperature

“…Finally, the grand old phenomenon of SCO continues to evolve keeping abreast with the contemporary developments in molecular magnetism and related topics. 5,[28][29][30][31][32][33][34][35][36][37][38][39] We are happy that the topic has chosen us to express interesting facets, as discussed in this script.…”

Optimized Local Synthetic Conditions Induce Size Reduction and Phase Purification in {[Fe(Htrz)2(trz)](BF4)}n Spin Crossover Particles

“…At the molecular level, one molecule can be in either one of the two states, but in the solid state, cooperative interactions may drive the occurrence of hysteretic properties resulting in a memory effect of interest for many applications . The evolution of this memory effect upon reduction of the material dimensions down to nanoparticles or thin films has been the subject of many studies in the last 20 years to evaluate the possibilities of integrating such systems into operating electronic devices. , As a general observation, the memory effect can be maintained, even if reduced in operating range, even in particles as small as a few tens of nanometers. − …”