STUDY OF ELECTRODEPOSITION OF COPPER-INDIUM MATERIAL FOR FABRICATION OF CIS THIN-FILM SOLAR CELLS

Abstract Copper-Indium material for the fabrication of CIS/CIGS thin-film solar cells and for applications as an alloy is one of the most auspicious materials currently being studied and has attracted significant interest in solar energy and other industries. In the past, there have been several methods used for the fabrication of chalcopyrite thin-film solar cells. However, one of the best methods in the industry is electrodeposition, which employs the principles of electrochemistry to deposit materials on a working electrode. The cyclic voltammetry and constant potential deposition studies have been conducted for the electrodeposited copper indium material. In order to better understand the electrochemistry behind the deposition of copper and indium, a systematic cyclic voltammeteric study was undertaken on a carbon electrode. In this thesis, several aspects of copper indium deposition have been studied which can be used as an elementary study to optimize parameters to get the final composition which will give maximum conversion efficiency. This study would also be an elementary study for further researches which would increase the efficiency of the CIS thin-film solar cells. The characterization was done by SEM, EDS, and XRD studies. Moreover, the effect of the addition of two different complexing agents, namely EDTA and trisodium citrate was studied. Complexing agents assist in the co-deposition process. Thus, in this research, samples with and without the usage of complexing agents were studied. Cyclic voltammograms produced reduction peaks around -0.2 V and -1 V versus SSC respectively for copper and indium using both trisodium citrate and EDTA complexing agents. The position of the peaks is similar using both the complexing agents proving the efficacy of EDTA as a suitable complexing agent. EDS studies provided compositional analysis for the films deposited by the constant deposition method. pH studies indicate no prominent peaks at more acidic pH. This could be attributed to the poor stability of the electrolyte solution at higher pH. Thus, it could be concluded that additional compounds need to be added to increase the stability of the solution if the pH has to be increased. The reason to perform SEM, EDS, and XRD characterization was to help identify the reaction mechanism, structure, and morphology of the films deposited under different conditions. Results of SEM studies showed that the grain size was small (2-20 μm) and there were cracks on the surface which could be avoided by changing the parameters. XRD analysis shows the presence of the CuIn layer and that (200) is the preferential plane to the growth of the CuIn films