Influence of precursor molar concentration on the structural, morphological, optical and electrical properties of PbS thin films deposited by spray pyrolysis technique using perfume atomizer

PbS thin films were deposited onto glass substrates at 400 °C using lead nitrate and thiourea as sources of Pb and S respectively. The molar concentration of precursor salts (both cationic and anionic) was varied as 0.025, 0.05, 0.075 and 0.1 keeping S/Pb ratio equal to 1. The structural studies reveal that the S:Pb concentration has a strong influence on the microstructural characteristics of the sprayed PbS films. The films were adherent to the substrate and well crystallized according to orthorhombic structure with the preferential orientation making a transition from (0 0 4) plane to (4 1 3) plane when S:Pb molar concentration increases. All the films have high optical transmittance > 70%. The optical band gap values are found to be in the range of 2.44 – 2.55 eV. The refractive index dispersion of the films obeys the single oscillator model. Electrical resistivity of all the films was found to be in the order of 102 Ωcm. PbS films fabricated by this simplified technique are found to be good in structural, optical and electrical properties which are desirable for window layers in solar cell applications.