Coupling Plasmonics and Charge Transfer Dynamics for Developing High-Performance Ag–SnO ₂ -Based UV–Visible Photodetectors

Rapid progress in optoelectronic technologies demands highly sensitive, broadband, and low-cost photodetectors (PDs) for next-generation optical sensing and imaging. In this study, high-performance silver (Ag)–tin oxide (SnO 2 ) nanocomposite (NC)-based PDs were successfully fabricated using a scalable and cost-effective dip coating technique. The surface modification of SnO 2 with Ag nanoparticles (NPs) noticeably enhanced the photoresponse of Ag–SnO 2 PDs. We observed nearly 22-fold increase in responsivity ( R λ ) (∼1.67 A/W) and external quantum efficiency (EQE) (∼750%), along with an order-of-magnitude enhancement in detectivity ( D *) (∼2.7 × 10 12 Jones) in the optimized Ag–SnO 2 PD under deep ultraviolet (UV) illumination. Moreover, the Ag–SnO 2 PDs not only demonstrate a higher R λ in the UV region but also have a noticeable R λ in the visible region (∼400−500 nm) in comparison to the bare SnO 2 PD, confirming its UV–visible applicability. The coupling of Ag with SnO 2 significantly accelerates the response of the PDs, leading to an approximately threefold reduction in response time compared to bare SnO 2 -based PD. The observed superior performance in Ag–SnO 2 PDs is explained by theoretical and experimental plasmon-mediated modification of charge carrier dynamics and Schottky barrier at the Ag–SnO 2 interface. The simplicity and scalability of the solution-based fabrication approach further underscore the potential of Ag–SnO 2 NCs for low-cost, large-scale integration in next-generation UV–Visible PD applications.