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

Antimony sulfide (Sb₂S₃) 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 Sb₂S₃ thin film PDs (glass/ITO/patterned ITO/TiO₂/Sb₂S₃/Au) with light-trapped ITO patterns to enhance absorbance and performance. Periodic cuboid-patterned ITO patterns with the sizes of 50 × 50 µm² 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 Sb₂S₃ 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/cm², the device achieves a responsivity of 4.5 A/W and a specific detectivity of 1.4 × 10¹³ Jones, demonstrating its weak-light detection ability. The Sb₂S₃ 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.