UV Photodetectors Based on Magnetic‐Field‐Assisted PLAL‐Synthesized Ag–Ag ₂ O Nanoparticles on Methylene‐Blue‐Sensitized Silicon

This article reports UV photodetectors fabricated using silver nanoparticles synthesized by magnetic‐field‐assisted pulsed laser ablation in liquid. Applying a 250 mT magnetic field confines the laser‐induced plasma, increases nucleation density, and yields uniformly sized, ligand‐free Ag–Ag 2 O nanoparticles with improved crystallinity and higher concentration. These nanoparticles are integrated into planar and porous n‐type silicon to form metal–semiconductor Schottky junctions. Devices are prepared with and without a 50 nm methylene blue (Mb) dye layer, which enhances UV–visible absorption and facilitates interfacial charge transfer, leading to improved carrier separation and transport. The combined plasmonic and dye‐sensitization effects significantly enhance photocurrent. In planar Si devices, the photocurrent increases from 34.3 to 2314 µA at 5 V, while porous Si devices show an increase from 166.6 to 2120 µA under the same illumination. The planar Mb:Ag‐NPs device achieves a responsivity of 77.20 mA W −1 and an external quantum efficiency (EQE) of 26.24%, whereas the porous counterpart reaches 69.20 mA W −1 and 23.52%. Time‐resolved measurements reveal faster rise and decay times in Mb‐sensitized devices, indicating reduced recombination. This article demonstrates a simple, surfactant‐free route for integrating magnetically engineered nanoparticles and dye‐sensitized interfaces to enhance responsivity, detectivity, and temporal behavior in silicon‐based UV photodetectors.