Influence of the physical properties on the antibacterial and photocatalytic behavior of Ag-doped indium sulfide film deposited by spray pyrolysis

Abstract

Spray pyrolysis was used to deposit indium sulfide (In₂S₃) films, with or without silver doping. The films are polycrystalline, and the inclusion of Ag in the In₂S₃ structure leads to the formation of a solid solution, with the crystallite size of the order of tens of nanometers. In₂S₃ films exhibit a semiconductive behavior, and the incorporation of Ag leads to an increase of the charge carrier concentration, enhancing the electrical conductivity of the films. The small polaron hopping mechanism, deduced by the fittings according to the double Jonscher variation, explains the evolution of the direct current (dc) conductivity at high temperature of the Ag-doped indium sulfide. From impedance spectroscopy, it was found that the doped film presents dielectric relaxation, and Nyquist diagrams indicate the importance of the grain and the grain boundaries’ contributions to the transport phenomena. The physical characteristics of the films have an influence on the photocatalytic performance, achieving photodegradation efficiency above 80% (85.5% in the case of Ag doping), and on the antibacterial activity. The obtained results indicate that indium sulfide films are good candidates for environmental and biological applications, confirming a multifunctional nature.