Determining the majority charge carrier, optical and structural properties of electrochemically deposited lead tin sulfide (PbSnS) thin films

Single phase lead tin sulfide (PbSnS) thin films have been successfully deposited on ITO-coated 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(NO3)(2), SnCl2.2H(2)O and Na2S2O3. This was followed by annealing in air at 250 degrees 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