Tailoring Electrical Stability of Indium Oxide Thin-Film Transistors via Solution Aging-Induced Defect Modulation

The stability and performance of solution-processed indium oxide (InO) thin-film transistors (TFTs) are critically influenced by defect formation at the interface between the channel and the gate dielectric. This study comprehensively investigated the impact of solution aging time (0 min to 3 h) on the electrical and optoelectronic characteristics of InO TFTs, with an emphasis on defect-state modulation and charge-transport mechanisms. Changes in key TFT parameters, including the threshold voltage, subthreshold swing, and field-effect mobility, were analyzed as a function of solution aging duration. Bias-stress measurements confirm that positive bias stress-induced electron trapping and negative bias stress-driven oxygen vacancy ionization significantly affect device stability. The photoresponse of the InO films exhibits a nonmonotonic trend; the persistent photoconductivity increases for short aging times and diminishes on aging beyond 1 h, underscoring the dynamic evolution of defect states. X-ray photoelectron spectroscopy indicates that prolonged aging promotes the formation of stable In–O bonds while reducing the density of oxygen vacancies and hydroxyl-related defects, thereby improving electrical stability. These findings confirm a direct correlation between solution aging time and device reliability, offering valuable insights into optimizing the processing conditions of InO films for next-generation oxide-semiconductor electronics and optoelectronic applications.