High-efficiency nitrene-based crosslinking agent for robust dielectric layers and high-performance solution-processed organic field-effect transistors

High-performance organic field-effect transistors (OFETs) need not only high-mobility organic semiconductors, but also suitable organic dielectric layers. OFETs with the polystyrene (PS) dielectric layer have shown superior electrical characteristics and operational stability levels due to the hydrophobicity of PS. However, PS is usually compatible with vacuum-evaporated semiconductors because the solution process dissolves the bottom PS layer, making it difficult to obtain a high-quality semiconducting film. In this study, we develop the chemically robust dielectric film 'FPS', made up of 5 wt% ethylene glycol bis(4-azido-2,3,5,6-tetrafluoro-benzoate) (sFPA) in a PS film. Addition of UV-responsive sFPA causes the film to become crosslinked after UV irradiation while maintaining its surface properties compared to the PS film. Crosslinking with a very small amount of sFPA is possible due to high crosslinking efficiency of sFPA, not requiring two specific functional groups. In addition, an as-cast FPS film is readily photo-patterned by UV irradiation with a shadow mask. The solution-processed TES-ADT semiconductor film shows a highly crystalline morphology on the FPS layer, and its OFETs show much higher field-effect mobility levels than those with the plain PS layer. These results are attributed to the chemical robustness of the FPS layer, and its favorable environment for growth of TES-ADT crystals. Therefore, we expect the FPS layer to be used as a versatile dielectric layer with various solution-processed semiconductors.