Biogenic synthesis of PbS nanoparticles by Micrococcus luteus and their application in high-performance photodetectors

This study reports the successful extracellular biosynthesis of lead sulfide (PbS) nanoparticles using non-motile, Gram-variable Micrococcus luteus bacteria. Optimization studies revealed optimal growth conditions for bacterial biomass and PbS production at room temperature, pH 7, and 96 h of incubation. The influence of precursor concentration on the growth and properties of PbS nanostructures was investigated. Characterization techniques, including X-ray diffraction, scanning electron microscopy, and FTIR spectroscopy, confirmed the formation of spherical, pure-phase PbS nanoparticles with sizes ranging from 150 to 250 nm. UV-visible absorption spectroscopy demonstrated strong absorption in the near-infrared region, indicative of the bandgap of PbS. Furthermore, an increase in precursor concentration resulted in a blue shift of the band gap. Utilizing these biogenic PbS nanoparticles, a high-performance photodetector device was fabricated with the architecture FTO/TiO₂/PbS/PANI/NiS/V₂O₅/Pt. The device exhibited excellent stability and repeatability in ON-OFF switching cycles, with a high detectivity of 30.9 × 10⁷ Jones and fast response times of 0.94 s (rise time) and 0.478 s (decay time). These findings demonstrate the potential of biogenic PbS nanoparticles for developing high-performance optoelectronic devices.