Facile and low cost chemosynthesis of nanostructured PbS with tunable optical properties

The present work reports on the chemosynthesis of nanocrystalline lead sulphide (PbS) thin films by a facile and cost-effective chemical bath deposition (CBD) method onto soda-lime glass substrates. The Xray diffraction (XRD) pattern shows the formation phase pure PbS with cubic crystal structure. Electronic structures and chemical states of PbS film have been performed by X-ray photoelectron spectroscopy (XPS). Field emission-scanning electron microscopy (FESEM) images show the transition from granular-to-cubic-to-cubo-octahedra like surface morphology with the increase in the deposition time from 20 to 90 min. The UV-vis-NIR absorption spectra of PbS thin films are measured, and a classical Tauc approach was employed to estimate their band gap energies. The increase in band gap energy from 0.99 to 2.06 eV with the reduction in crystallite size evinces quantum size effect. This work demonstrates a simple and effective solution approach to deposit PbS nanostructured thin films having predominant quantum confinement. This approach would be helpful in nano-PbS sensitized oxide based solar cells, which are recently under intensive investigations