The physical properties and photoresponse of AgIn5S8 polycrystalline film electrodes fabricated by chemical bath deposition

The AgIn5S8 polycrystalline films were grown on indium–tin-oxide-coated glass substrates by using chemical bath deposition. New procedures for the growth of AgIn5S8 films are presented. The solutions containing silver nitrate, indium nitrate, triethanolamine, ammonium nitrate and thioacetamide in acidic solution were used for the growth of AgIn5S8 film electrodes. The influences of various deposition parameters on structural, optical, and electrical performances of films have been investigated. The X-ray diffraction patterns of the samples demonstrate the presence of polycrystalline structures of AgIn5S8 phase in these films and show AgIn5S8 phase is the major crystal structure. With different substrates, the different crystal structures were obtained. The thickness, band gaps and carrier densities of these samples determined from transmittance spectra and electrochemical analysis are in the range of 647–1123 nm, 1.70–1.73 eV and 4.02 × l014–6.36 × l014 cm−3, respectively. The flat band potentials of these samples are located between −0.293 and −0.403 V versus normal hydrogen electrode with the Mott-Schottky measurements. The conduction bands and valance bands of films determined from flat band potentials are in the range of −0.517 to −0.618 V, and +1.213 to +1.082 V versus normal hydrogen electrode. The maximum photocurrent density of samples prepared in this study with external potential kept at 3.5 V was found to be 6.0 mA/cm2 under the illumination with white light intensity kept at 100 mW/cm2.