Self-Powered Sb₂S₃ Thin-Film Photodetectors with High Detectivity for Weak Light Signal Detection

Photodetectors (PDs) for weak light signal detection have wide applications for optical communication and imaging. Antimony sulfide (Sb₂S₃) as a nontoxic and stable light-sensitive material becomes a promising candidate for weak light PDs, which are developing in the direction of high response, high speed, and low cost. Herein, a self-powered Sb₂S₃ PD with the structure of FTO/TiO₂/Sb₂S₃/Au is developed to achieve weak light detection for 300-750 nm visible light. We control the Sb₂S₃ thickness with about 460 nm to match depletion region width (438 nm) and obtain an excellent photoresponsivity and 3 dB bandwidth. Furtherly, we prepare pyramid structure polydimethylsiloxane (PDMS) on the illuminating surface to enhance the performance of weak light detection by light-trapping effects. The photocurrent of Sb₂S₃ PD with 20 μm-sized PDMS texture achieves 13.6% improvement compared with the control one. Under weak 530 nm light illumination of 1 μW cm^-2, the self-powered Sb₂S₃ PD with PDMS achieves high responsivity (3.41 A W^-1), large detectivity (2.84 × 10¹³ Jones), and ultrafast speed (15 μs). The present Sb₂S₃ PD and light-trapping strategy are expected to provide an alternative to future commercial weak light detection applications.