Self-powered photoresponse and electrolyte-driven performance optimization in MoS 2 -Se nanocomposite PEC photodetector

Abstract Photoelectrochemical (PEC) photodetectors have emerged as promising candidates for next-generation optoelectronic devices owing to their ability to operate in a self-powered mode while ensuring efficient light-to-electricity conversion. In this work, MoS 2 -Se nanocomposites with varying selenium concentrations, previously optimized in our earlier study, were systematically investigated through comprehensive electrolyte engineering and operational parameter tuning to enhance PEC performance. The influence of electrolyte type, electrolyte concentration, applied bias voltage, and illumination intensity on device characteristics was examined in detail. The optimized MoS 2 -Se nanocomposite exhibited significantly enhanced responsivity of 42.14 μA W −1 and a rapid response time of 0.09 s under optimized conditions, attributed to improved charge separation and efficient interfacial charge transfer. Notably, the device exhibited clear self-powered photodetection at 0 V bias with a fast rise–decay response of 0.7 s, confirming the presence of an effective built-in electric field. This systematic study highlights the critical role of electrolyte optimization and interfacial dynamics in maximizing PEC performance, establishing MoS 2 –Se nanocomposites as efficient and tunable materials for sustainable, bias-free photodetector applications.