On-Chip Full-UV-Band Photodetectors Enabled by Hot Hole Extraction

Achieving on-chip, full-UV-band photodetection across UV–A (315–400 nm), UV–B (280–315 nm), and UV–C (100–280 nm) bands remains challenging due to the limitations in traditional materials, which often have narrow detection ranges and require high operating voltages. In this study, we introduce a self-driven, on-chip photodetector based on a heterostructure of hybrid gold nanoislands (Au NIs) embedded in H-glass and cesium bismuth iodide (Cs₃Bi₂I₉). The Au NIs act as catalytic nucleation sites, enhancing crystallinity and facilitating the vertical alignment of the interconnected Cs₃Bi₂I₉ petal-like thin film. A built-in electric field developed at the heterojunction efficiently separates hot holes generated in the Au NIs under UV illumination, transferring them to the valence band of Cs₃Bi₂I₉ and minimizing recombination losses. The device demonstrates an ultrahigh open-circuit voltage of 0.6 V, exceptional responsivity of 0.88 A/W, and a detection threshold of 90 nW/cm², outperforming the existing thin film-based UV photodetectors under self-driven mode. Long-term stability tests confirmed robust operational reliability under ambient conditions for up to eight months. This architecture, driven by efficient hot hole dynamics, represents a significant advancement for full-UV-band optoelectronics with promising applications in environmental monitoring, flame detection, biomedical diagnostics, and secure communication systems.