Light-Trapping ITO Patterning Enables High-Detectivity Sb2S3 Thin Film Photodetectors for Imaging Applications

Antimony sulfide (Sb 2 S 3 ) photodetectors (PDs) show great prospects in applications of optical communication and imaging. The detector performance is significantly influenced by reflection losses at the incident surface, particularly under weak-light conditions. Herein, we propose self-powered Sb 2 S 3 thin film PDs (glass/ITO/patterned ITO/TiO 2 /Sb 2 S 3 /Au) with light-trapped ITO patterns to enhance absorbance and performance. Periodic cuboid-patterned ITO patterns with the sizes of 50 × 50 µm 2 and depth of 250 nm are fabricated using photolithography and magnetron sputtering, which achieves about a 21% absorbance enhancement of visible light and 16% photocurrent increase of Sb 2 S 3 PDs. Meanwhile, the patterned ITO slightly expands the heterojunction contact area, which enhances the built-in electric field and the carrier extraction efficiency. Under the 530-nm light illumination of 5 µW/cm 2 , the device achieves a responsivity of 4.5 A/W and a specific detectivity of 1.4 × 10 13 Jones, demonstrating its weak-light detection ability. The Sb 2 S 3 PDs array, featuring fast response and a wide 3 dB bandwidth, has demonstrated image sensing capabilities by clearly resolving variations in bright and dark fields, showcasing application potentials.