study of synthesis dependent physicochemical and optoelectronic properties of nanocrystalline lead sulfide (pbs) thin films deposited using chemical bath deposition method

The present paper deals with the synthesis of pbs thin films using cost cost-effective chemical route over the glass substrates at room temperature for studying the effect of deposition time on physicochemical and optoelectronic properties with the intension to test the application as an ammonia gas sensor. these 10, 20, 30, 40, and 50 min deposited thin films have been characterized for their structural properties using x-ray diffraction patterns (xrd), which revealed stoichiometric pbs thin films having a polycrystalline cubic structure with orientation along the (111) and (002) planes, with crystallite sizes varying from 18 to 22 nm. the raman spectrum shows peaks at 92 and 143 cm-1, representing the transverse and longitudinal oscillations for chemical ionic bonds, respectively. the elemental analysis confirmed from the energy dispersive x-ray analysis spectrum infers expected and observed chemical compositions in pbs thin films. the surface topography and morphology have shown the floral distribution of grains over the substrate surface. this exhibited the effect of deposition time in the form of flower growth. pbs synthesized for 40 min represents a completely grown flower, while dipping time less than 40 min shows a slightly varying nature of the flower. such topography could be useful for surface-related applications. the optical absorbance spectra represented the higher absorbance coefficient and energy band gap calculated to be 1.48 ev, which inferes the polaron-induced charge transfer. the ammonia gas sensitivity calculated as a function of optical absorbance in air and under gas impurging has shown at most 80% sensitivity for the thin film grown by dipping 40min in the precursor solutions.