AC impedance and cyclic voltammetry studies on PbS semiconducting film prepared by electrodeposition

Semiconducting lead sulfide film was deposited on Stainless Steel (SS) electrode by cyclic voltammetry (CV) at room temperature. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the electrochemical properties of PbS film in Na2SO4 solution. The voltammetric results showed that oxidative dissolution of PbS film occurred at about 0.21 V vs. Ag/AgCl and total film detachment from the surface occurs with increasing potential. It is concluded that the electrode surface was not passivated by sulfur produced from oxidative dissolution of PbS film. Also, cathodic reduction of the film continued to beyond the hydrogen evolution at −1.35 V vs. Ag/AgCl. Capacitive parts of impedance spectra showed frequency dispersion and constant phase element (CPE) was used instead of capacitor to simulate the interfacial capacitance in the corresponding equivalent circuit. The flat band potential and carrier concentration were determined from Mott–Schottky plot and are estimated to be −0.32 V and 1.6 × 1023 m−3 respectively. The film was p-type semiconductor.