Superconcentrated aqueous electrolyte and UV curable polymer composite as gate dielectric for high-performance oxide semiconductor thin-film transistors

Due to the increasing miniaturization, lightweight, wearable, and portable electronic devices, there is an increasing need to reduce power consumption through the lower operating voltages of thin-film transistors (TFTs). In this study, we proposed a “water-in-bisalt” (WiBS) and an ultraviolet (UV)-curable polymer composite material, which is an aqueous electrolyte with a high capacitance, and realized a dielectric material for low power consumption and a stable voltage range of TFTs that can be handled in the ambient condition. We fabricated a free-standing WiBS/polymer dielectric film with a high capacitance value of 6.72 uF/cm² at 0.5 Hz and high electrochemical stability by embedding a WiBS electrolyte into the UV crosslinked polymer network by photocuring. The devices of InO_x TFTs using WiBS/polymer dielectric films show excellent electrical characteristics: an on/off current ratio of over 10³, a subthreshold swing of 110 mV/dec at a drain voltage of 0.1 V, and a linear field-effect mobility of 30.7 cm²/Vs at a drain voltage of 0.1 V and a gate voltage of 1 V.