Enhanced UV-C Detection Performance of Perovskite Photodetectors via Controlled Surface Patterning

Ultraviolet (UV)-C photodetectors based on perovskite semiconductors are attractive because of their solution processability and excellent optoelectronic properties, but UV-induced degradation limits conventional UV-based processing. Here, controlled ultraviolet light exposure is repurposed as a surface-engineering and patterning strategy. Shadow-mask-assisted irradiation selectively thinned the perovskite surface, while X-ray diffraction and UV-vis spectroscopy indicated that the main crystalline perovskite phase and overall optical absorption characteristics remained largely unchanged. Patterning conditions were systematically varied using patterning times of 3-10 min and circular pattern diameters of 0.3-1.0 mm. The optimized condition of a 7 min patterning time and a 0.5 mm pattern diameter reduced the dark current and enhanced the photocurrent, resulting in improved responsivity, external quantum efficiency, and specific detectivity. Cross-sectional microscopy and profilometry confirmed controllable surface thinning without macroscopic delamination, while XRD indicated preservation of the detectable crystalline perovskite phase under the investigated conditions. The observed performance enhancement is discussed in terms of possible changes in near-surface electrical losses and optical/carrier-transport pathways associated with controlled surface thinning. These results demonstrate that controlled ultraviolet light irradiation can function as a surface-modification strategy for improving perovskite UV photodetectors while maintaining the principal crystallographic and optical characteristics under the investigated conditions.