An opto-electrically decoupled phototransistor for solar-blind ultraviolet detection

Solar-blind ultraviolet (UV) photodetectors have been primarily developed using ultrawide-bandgap (UWBG) semiconductors, where the wide bandgap enables low dark current and intrinsic solar-blind selectivity. However, the same wide-bandgap nature limits carrier modulation, particularly doping control and junction engineering, imposing fundamental challenges for high-sensitivity detection and scalable integration. Here, we demonstrate an opto-electrically decoupled solar-blind UV phototransistor by integrating a perovskite p–n photovoltage generator with a carbon nanotube (CNT) field-effect transistor. This architecture separates photon conversion from carrier transport, where the perovskite heterojunction generates a photovoltage that electrostatically modulates the CNT channel without interfacial carrier transfer. Under 265 nm illumination, the device achieves a responsivity of 2908 A W−1, a specific detectivity of 1.6 × 1013 Jones, and rise/decay times of 5.6/15.5 ms. The low-temperature fabrication process is compatible with silicon back-end-of-line integration, providing a route toward highly integrated solar-blind UV sensing with front-end bandpass filtering, beyond conventional UWBG semiconductor systems.