Cyclic voltammetric and characterization studies of electrodeposited copper-indium for thin-film solar cell application

Copper-indium layers were grown on a carbon substrate by a one-step electrodeposition technique. Four deposition electrolytes were prepared: Two unitary electrolytes comprising of 300 mM copper (II) chloride and 700 mM trisodium citrate and 300 mM indium (III) chloride and 700 mM trisodium citrate; two binary electrolytes comprising of 300 mM copper (II) chloride, 300 mM indium (III) chloride and 700 mM trisodium citrate for deposition at potentials of -0.6 V and -0.9 V, respectively. The pH of the solution was left unaltered at 4.8. X-ray diffraction studies showed the produced copper indium layers had an amorphous structure. From the scanning electron microscopy studies, it was found that copper indium layers indicated a small grain size and grain shape was irregular. The structure was not compact. Energy dispersive spectroscopy showed presence of low percentages of copper and indium in all four samples and stoichiometric molar ratios of Cu:In of 1:1 can be achieved using deposition potentials between -0.6 to -0.9 V. SEM, EDS and XRD characterization helps in the identification of the reaction mechanism, the structure and morphology of the films deposited under different conditions. These characterization studies will assist in enhancing the efficiency of the thin-films deposited for maximum conversion of sunlight to electricity using this sustainable method. In this present study, an attempt has been made to obtain near stoichiometric films for higher efficiencies.