Enhanced Illumination Stability of Solution-Processed Oxide Thin Film Transistor by Anion and Cation Co-Doping InSnO-Based Channel

Solution-processed oxide thin film transistor (TFT) has gained significant attention due to the potential for cost-effective fabrication, yet they generally suffer from compromised device performance, particularly concerning illumination stability. To address this challenge, we proposed an anion and cation co-doping strategy through the fabrication of top-gate Tungsten-Fluorine co-doping Indium-Tin-Oxide (WITOF) TFT. The optimized WITOF TFT achieves remarkable electrical properties, a high mobility of 6.94 cm2V<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{-{1}}$ </tex-math></inline-formula>s<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{-{1}}$ </tex-math></inline-formula>, Ion/Ioff exceeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{6}}$ </tex-math></inline-formula>, near-zero threshold voltage of 0.04 V, and superior negative bias illumination stress stability with minimal threshold voltage shift of −0.102 V. The enhanced performance mainly originates from two synergistic mechanisms, the formation of robust W-O chemical bonds, and effective passivation of oxygen vacancies by low-energy F- ion substitution. The anion and cation co-doping strategy significantly suppresses trap state formation in the ITO semiconductor layer, leading to optimized charge transport characteristics through improved carrier mobility and reduced charge scattering. These findings not only establish WITOF as a promising channel material for high-performance oxide TFTs, but also provide a generalizable framework for advancing solution-processed semiconductor technologies through targeted ionic engineering.