Toward Next‐Generation High‐Speed Communication and Imaging: Solution‐Processed Sb ₂ (S,Se) ₃ /CdS Heterojunction for Ultrafast Self‐Powered Photodetector

The pursuit of multifunctional photodetectors (PDs) that combine broadband responsivity, high specific detectivity under low-light conditions, and robust operation across extreme temperatures is a cornerstone for advancing next-generation optical communication and imaging systems. Herein, we report a self-powered PD FTO/CdS/Sb₂(S,Se)₃/Au via a low-cost solution-processed method. At zero bias, the Sb₂(S,Se)₃-based PD exhibits a responsivity of 0.6 A/W, a specific detectivity of 7.68 × 10¹² Jones, ultrafast response/recovery times of 1.13/1.90 µs, and a 3 dB bandwidth of 175 kHz under 785 nm illumination (4.09 µW/cm²). Most strikingly, the unencapsulated device exhibits excellent stability from 10 to 575 K, which is rarely reported for Sb₂(S,Se)₃-based PDs. The practical multifunctional applicability of this single PD is further validated by its successful integration as a high-speed receiver in a visible light communication system and a sensing pixel for high-resolution imaging. Compared with the reference Sb₂(S,Se)₃ sample, the performance enhancement of the Sb₂(S,Se)₃/CdS heterojunction PD arises from the built-in electric field (E_bi) that enables the effective carrier separation/extraction, and the heterojunction structure that reduces the interface/bulk trap densities of the Sb₂(S,Se)₃ film. This work opens a promising avenue in near-infrared imaging, light communication and extreme-environment sensing.