Integration of the evaporable spin-crossover complex [Fe(HB(1,2,4-triazol-1-yl)₃)₂] into organic field-effect transistors: towards multifunctional OFET devices

Integrating stimuli-responsive molecular switches into organic electronic devices opens interesting perspectives to achieve unprecedented functionalities. However, significant challenges arise in maintaining device functionalities and ensuring synergy with the molecular properties. Here, we described three different ways of incorporating thin films of the molecular spin crossover (SCO) complex [Fe(HB(1,2,4-triazol-1-yl)₃)₂] into an organic field-effect transistor (OFET) device. The fabrication of high-quality films was enabled by the use of vacuum thermal evaporation, which permitted the deposition of the SCO compound either on the surface of the organic semiconductor or at the semiconductor/dielectric interface. In device configurations where the SCO layer was not in contact with the conduction channel, changes in the drain-source current were observed near the spin crossover temperature, suggesting a potential synergistic effect. These results provide valuable guidance for the design and integration of bistable-material-based functional devices.