Enhanced photodetection properties of PbS thin films prepared via nebulizer spray pyrolysis (NSP) technique: Effect of coating temperature

The present study examines the effect of substrate temperature on the photodetection capabilities of lead sulfide (PbS) thin films prepared on glass substrates using a cost-effective nebulizer spray pyrolysis (NSP) technique. The substrate temperature varied from 175 °C to 300 °C, with a 25 °C increment for each film. The X-ray diffraction analysis confirmed the formation of a face - centered cubic structure. In addition, the PbS crystallinity was enhanced by raising the substrate temperature, the largest crystallite size (77 nm) was observed at 275 °C deposited film. The development of nanograins and the change in grain size due to the substrate temperature were confirmed by the obtained FESEM images. EDX spectra demonstrated the presence of Pb and S elements in the film deposited at 275 °C. The optical direct bandgap decreased from 1.92 eV to 1.70 eV with increasing substrate temperatures from 175 °C to 275 °C, but significantly increased to 1.75 eV at 300 °C. All the prepared PbS thin films demonstratde an excellent photodetection capabilities. However, the PbS film coated at 275 °C exhibited high Responsivity (7.04 × 10⁻² A/W), Detectivity (2.99 × 10⁹ Jones), and External quantum efficiency (16.4 %) in comparison to the other deposited thin films.