Light‐Trapping ITO Patterning Enables High‐Detectivity Sb 2 S 3 Thin Film Photodetectors for Imaging Applications

ABSTRACT 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.