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.