[Abstract]

The development of transparent and high-performance p-type semiconductors as a counterpart of n-type metal oxide semiconductors has attracted significant interest for the integration of complementary circuits and p–n junction devices. This study investigates the effect of trace O₂ for high-performance and solution-processed inorganic p-channel Zn-doped copper iodide (CuI) thin-film transistors (TFTs) via a combined computation–experiment approach. The absorbed O₂ molecules in the CuI film can occupy iodine vacancies, acting as trap passivator. Meanwhile, the strong electronegativity of O₂ enables electron capture from the CuI matrix, leading to p-doping. Trace O₂-treated Zn-doped CuI TFTs exhibit significantly improved electrical performance compared to untreated devices. Optimized TFTs exhibit a high field-effect hole mobility of 4.4 cm² V⁻¹ s⁻¹, high on/off current ratio of ≈10⁷, and small hysteresis. These findings provide a clear basis for realizing reproducible and high-performance metal-halide (e.g., CuI and perovskite) optoelectronic devices using low-cost solution process.