Experimental investigation of the effect of indium content on the CuIn5S8 electrodes using electrochemical impedance spectroscopy

This paper reports on the use of electrochemical impedance spectroscopy to investigate the electrochemical behavior of spinel CuIn5S8/electrolyte interface. The CuIn5S8 spinel films have been potentiostatically deposited onto indium tin oxide (ITO)-coated glass substrate. CuCl2 and InCl3 mixed solutions with different [Cu]/[In] ratios were used as cation precursor and Na2S2O3 as the anion precursor in acidic solution and at room temperature. The effect of the [Cu]/[In] ratio in the precursor solution on the structural, chemical stoichiometry, and morphological properties of prepared samples, as well as the electrochemical behavior of the CuIn5S8/electrolyte interface was investigated. The electrochemical impedance spectroscopy data have been modeled using an equivalent circuit approach. Several parameters such as, flat-band potential and free carrier concentration were determined by the change in the Mott–Schottky plots.