Single phase lead tin sulfide (PbSnS) thin films have been successfully deposited on ITOcoated glass substrates using a 3-electrode electrochemical cell having graphite as the counter electrode and Ag/AgCl as the reference electrode. In this single-step electrodeposition, the PbSnS precursor thin film was directly electrodeposited on the conductive substrate from the electrolytic bath solution which contained Pb(NO 3 ) 2 , SnCl 2 .2H 2 O and Na 2 S 2 O 3 . This was followed by annealing in air at 250 °C for an hour to improve the crystallinity. The annealed films were characterized by a variety of techniques. Powder X-ray diffraction revealed peaks which were indexed to the orthorhombic phase of PbSnS with preferred orientation along the (112) plane. Seebeck coefficient studies confirmed the type of charge carrier of the film. SEM micrographs showed a compact morphology composed of spherically shaped well defined grains covering the entire substrate. EDAX analysis of the film was consistent with the formation of PbSnS. Optical absorption measurements revealed the existence of a direct transition with an estimated band gap of 1.68 eV

A study has been carried out to investigate the effect of the concentration of Sn in the metallic precursor on the structure, morphology, optical and electrical properties of PbSnS thin films. The films were directly electrodeposited on ITO-coated glass substrates using a 3-electrode electrochemical cell having graphite as the counter electrode and Ag/AgCl as the reference electrode. Several depositions were carried out, with each deposited film having a different concentration of Sn in the metallic precursor whilst all other parameters were kept constant for all the films. Post deposition annealing was carried out in air at 250 o C for an hour. A variety of techniques were used to characterize the films. Results showed that the increase in Sn concentration did not modify the structure and preferred orientation of the films. However, it caused a slight increase in the average grain size of the films and electrical conductivity. All the films showed direct transition with the optical band gap reducing with increasing Sn concentration. The refractive index of the films showed anomalous dispersion behaviour within the UV region, and normal dispersion in the visible and infrared regions, whilst following an increasing trend with the grain size. SEM image showed spherically shaped grains of different sizes distributed randomly with good coverage across the entire area of the substrate. The EDAX spectrum was consistent with formation of the ternary PbSnS compound on ITO-coated glass substrate. Overall results indicate that, the optical and electrical properties of the electrochemically deposited PbSnS thin films can be tuned to make them suitable for specific applications by varying the concentration of Sn in the metallic precursor.