Fabrication and Characterization of Nanocrystalline Lead Sulfide Thin Film for Visible Light Photodetector

This study focuses on the preparation of a high-performance visible light photodetector using nanocrystalline lead sulphide (PbS) thin films. The thin films were deposited onto glass substrates via the chemical bath deposition technique, utilizing an aqueous solution of lead acetate and thiourea. The structural study carried out on the deposited films by X-ray diffraction exhibited a cubic crystal structure with a PbS phase. The optical characteristics of PbS thin films were investigated employing UV-Vis absorption spectroscopy. The absorption spectroscopy was carried out in the wavelength range of 400–1000 nm. The absorbance spectra were utilized to calculate the spectral dependence of several optical parameters: band gap, refractive index, extinction coefficient, dielectric constant, and optical and electrical conductivity. The photocurrent was measured in nanocrystalline PbS thin films under the illumination of specific LED wavelength sources. The quality of the PbS thin film as a photodetector was investigated by determining the rise time, decay time, photosensitivity, specific detectivity, and external quantum efficiency.