Electrodeposition of CuInSe2 on TiO2 coated TCO electrodes

M. H. VALDÉS; A. GOOSSENS; M. VAZQUEZ

Niza, Francia

Congreso; 61st Meeting of the International Society of Electrochemistry.; 2010

International Society of Electrochemistry

CuInSe2 (CISe) thin films were electrodeposited on TiO2 thin films previously deposited on TCO/glass substrates by chemical spray pyrolysis. CISe was electrdeposited from a single aqueous solution containing Cu+2, In+3 and HSeO3- ions at a molar ratio of 1:4:2, KCl as supporting electrolyte and diluted HCl to adjust the pH between 2-2.5. Different CISe films were obtained at fixed potentials between -0.7 and -1 V vs. SCE and deposition times between 5 and 60 minutes. The film growth has been studied by cyclic voltammograms and characterized by Raman spectroscopy, XRD and absorption spectroscopy. The cyclic voltammograms indicate that the film formation starts with the deposition of CuSe compounds and then In is successively incorporated leading to CISe formation. Besides, the as-deposited material presents secondary phases that can be attributed to CuxSe compounds and vacancy ordered compounds like CuIn3S5 and CuIn5S8. Raman and XRD measurements show that CISe is the main component of the film, presenting the main A1 vibrational mode and the (112) diffraction peak, respectively. However, the presence of undesirable secondary phases is also evident. Furthermore the crystallinity of as-deposited films is very low, so that a thermal treatment is necessary to enhance and to promote CISe formation while reducing the presence of secondary phases in the material. To avoid oxidation, the annealing step has been performed in argon atmosphere, at temperatures between 300 – 400 ºC during 30 minutes. After the thermal treatment, the crystallinity of CISe and the overall chemical composition improves. Nevertheless, CuxSe compounds remain in the material and need to be further removed by chemical etching in KCN solution.