Design of Stepped Heterostructure Indium-Based Oxygen Sulfide Assisted for High-Performance Photoelectrochemical Photodetectors

Self-powered photodetectors for optical communication fields will play a key role in the future. To achieve high-performance underwater self-powered photoelectrochemical (PEC) photodetectors, herein, we construct a stepped and self-powered indium-based oxygen sulfide (In₂O₃-In₂S₃) heterostructure photodetection device through the energy band design. The obvious energy level difference of conduction band in type II In₂O₃-In₂S₃ heterostructure device with stepped energy band structure achieves efficient separation and rapid transport of photogenerated carriers, significantly extending the carrier lifetime and greatly delivering rapid response speed with short raise/decay times of 3.96/4.02 ms, high responsivity of 41.3 mA W^-1, and ultrahigh detectivity of 0.89 × 10¹³ Jones. Additionally, the introduction of In₂O₃ in heterostructure separates the photogenerated holes from In₂S₃, avoiding the photocorrosion behavior of In₂S₃ and prolonging the long-term stability to 3000 s. Importantly, the heterostructure engineering expands the detection range (for 635 and 850 nm lasers) of the In₂O₃-In₂S₃ photodetection device under weak-light scenes with respect to In₂S₃. Based on above results, this research provides new insight for the design and preparation of high-performance self-powered PEC detectors for wide-spectrum and highly stable photoelectric communication fields underwater scenes.