Ultraviolet–Visible Photodetector Driven by Local Electrostatic Field from Chargeable Electret

Abstract Metal oxide semiconductors have been developed for ultraviolet–visible photodetectors, but improving sensitivity has remained a challenge due to poor mobility and carrier losses. In this study, a high‐performance photodetector is achieved by implementing a chargeable electret to regulate carrier transmission properties in the CuBi 2 O 4 (CBO) conductive channel. As expected, the positively charged device shows improved performance, with a broadband detection range covering 250–600 nm, maximum responsivity and detectivity of around 10.65 A W −1 and 8.56 × 10 12 Jones, and a fast rise and decay time of 50 and 300 µs, respectively. Mechanism analyses suggest two roles of the electret layer: 1) positive charges in the electret layer attract electrons and leave a pure hole conductive channel with less carrier recombination and trapping; 2) holes in the conductive channel move in one direction with less carrier collision and scattering. This work has demonstrated an effective strategy for providing a durable and stable ultra‐high electrostatic field to improve the sensitivity of photodetectors.