Influence of Annealing on Solution-Processed Indium Oxide Thin-Film Transistors Under Ambient Air and Wet Conditions

The effect of annealing on solution-processed indium oxide (In₂O₃) films was investigated under ambient air and wet conditions at 250 °C, 300 °C, and 350 °C, respectively. The air-annealed films exhibited excellent thin-film transistor characteristics including field-effect mobility of 0.11-3.53 cm²/Vs and subthreshold slope of 0.28-0.36 V/dec. Whereas the wet-annealed films showed a conductor-like behavior due to >100 times higher carrier concentration than the air-annealed films. The results of X-ray photoelectron spectroscopy supported the decrease of hydroxyl groups in the In₂O₃ films by wet-annealing, reducing their electron trap states and leading to more charge carriers.