Investigation of growth parameters of CuInTe2 thin films by electrodeposition technique

Abstract

Copper indium di-telluride (CuInTe2) is a promising semiconductor material for photovoltaic applications because of its suitable optoelectronic properties. Among the various deposition techniques available for the preparation of CuInTe2 thin films, method of electrodeposition is an attractive technique because of its simplicity, low cost and possibility of making large area thin films. In this investigation, potentiostatic electrodeposition of CuInTe2 thin films on fluorine doped tin oxide (FTO) was studied using a three electrode electrochemical cell containing an aqueous solution of CuCl, InCl2 and TeO2. pH of the solutions was adjusted by adding ultra pure HCl. The counter electrode was a graphite rod and reference electrode was Ag/AgCl. Electrolytic solutions were prepared with deionised water and 99.995 % pure chemicals. Prior to the film deposition FTO substrates were degreased in acetone and rinsed with deionised water followed by 2 min ultra-sonication. Cyclic voltammograms were used to investigate the growth parameters; deposition potential, concentration, proportion of CuCl, InCl2 and TeO2, pH, temperature and stirring speed of the bath. In order to grow the photoactive CuInTe2 thin films, set of samples were prepared by slightly changing the deposition potential using the growth parameters obtained from cyclic voltammetric curves. Photoactive performance (Voc and Isc) of the films were characterized using I-V measurements in PEC containing aqueous solution of Na2S2O3. Highest photoactivity is given when the film deposited at -600 mV Vs Ag/AgCl for 20 min in the electrolyte containing aqueous solution of 1 mM CuCl, 20 mM InCl2 and 2 mM TeO2. Deposition temperature, pH and stirring speed of the bath were room temperature, 1.5 and 125 rpm respectively. Annealing temperature and time were 4000C and 20 minutes respectively. The preliminary results of this study suggest the possibility of growing photoactive p-CuInTe2 thin films by single step electrodepostion technique.