Electrodeposition of CIGS nanostructure photovoltaic absorber layers: effect of deposition time

Abstract

Electrodeposited CIGS absorber layers are fabricated by a three-stage electrodeposition process in which: (a) CIGS is electrodeposited in the first stage, (b) Cu is electrodeposited in the second stage, and (c) an In layer is deposited in the final third stage. All films are electrodeposited from an aqueous solution containing CuSO₄, InCl₃, SeCl₄ and GaCl₃ (pH around 1.5 adjusted with H₂SO₄) at room temperature in a three-electrode cell configuration. The electrodeposited films are selenized at high temperature under argon atmosphere. The effects of deposition parameters such as: the deposition time and potential; and type of substrate were investigated. It was found that morphology and particle size of the products could be greatly affected by these parameters. As a result, under the same condition, the particles size of CIGS films electrodeposited on the FTO glass as substrate are smaller than the particles size of CIGS electrodeposited on the Mo-coated glass. The In, Ga and Cu–In–Ga–Se electrodeposition systems were investigated by cyclic voltammetry. CIGS nanostructures were characterized by X-ray powder diffraction, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy, atomic force microscopy, cross-section SEM, and UV–Vis diffuse reflectance spectroscopy.