Spectrally Selective Hole Extraction Structure Enables a Self-Powered Perovskite Solar-Blind Photodetector with Record Responsivity and Detectivity

Photodiode-type solar-blind photodetectors (SBPDs) with the self-powered feature hold great promise for applications in unattended secure communication, flame detection, and missile warning. However, the responsivity of SBPDs is usually limited due to the severe solar-blind (SB) light extinction in substrates and charge transport layers. Herein, a spectrally selective hole extraction structure (SHE) is proposed for high-efficiency perovskite SBPDs. The SHE consisting of a tandem Fabry–Perot cavity and energy-level-matched hole transport layer endows the device with narrowband absorption in the SB region and optimized charge extraction capability from the CsPbI₂Br perovskite. The optimized SHE exhibits a peak transmittance of 27% at 255 nm and a half maximum at full width of 28 nm. Under SB light illumination, the champion device achieves a responsivity of 56.20 mA W⁻¹ and a detectivity (D^*) of 2.86 × 10¹³ Jones, which are the record values among the reported results. The approach demonstrated here paves the way for the optical and electrical design of perovskite photodetectors with spectrally selective detection.