High-performance CuI-based ultraviolet phototransistors

Transparent copper iodide (CuI) holds significant promise as an emerging semiconductor for high-performance ultraviolet (UV) photodetectors, owing to its high mobility and suitable band gap, which enables efficient UV absorption while suppressing visible light. However, its intrinsic high hole concentration results in extremely high dark current, leading to low signal-to-noise ratio and detectivity. To address this issue, we deposited a Zn-doped CuI channel and fabricated phototransistors using a low-cost solution process at low temperatures. By modulating the hole concentration and involving gate bias modulation, we achieved superior figures of merit for 365 nm UV detection. These include a high responsivity of 1.9 × 10 3 A/W, a detectivity of up to 2.8 × 10 14 Jones, and an impressive external quantum efficiency of 6.4 × 10 5 %. To the best of our knowledge, these values represent the highest performance among all reported CuI-based photodetectors. Our results demonstrate the significant potential of CuI phototransistors for future large-area, low-cost ultraviolet detection systems.