Aqueous Solution-Processable, Flexible Thin-Film Transistors Based on Crosslinked Chitosan Dielectric Thin Films

The hydrophilic character of chitosan (CS) limits its use as a gate dielectric material in thin-film transistors (TFTs) based on aqueous solution-processable semiconductor materials. In this study, this drawback is overcome through controlled crosslinking of CS and report, for the first time, its application to aqueous solution-processable TFTs. In comparison to natural CS thin films, crosslinked chitosan (Cr-CS) thin films are hydrophobic. The dielectric properties of Cr-CS thin films are explored through fabrication of metal–insulator–metal devices on a flexible substrate. Compared to natural CS, the Cr-CS dielectric thin films show enhanced environmental and water stabilities, with a high breakdown voltage (10 V) and low leakage current (0.02 nA). The compatibility of Cr-CS dielectric thin films with aqueous solution-processable semiconductors is demonstrated by growing ZnO nanorods via a hydrothermal method to fabricate flexible TFT devices. The ZnO nanorod-based TFTs show a high field-effect mobility (linear regime) of 10.48 cm² V⁻¹ s⁻¹. Low temperature processing conditions (below 100 °C) and water as the solvent are utilized to ensure the process is environmental friendly to address the e-waste problem.