In situ monitoring of electrophoretic deposition of Cu2ZnSnS4 nanocrystals

Abstract

Cu₂ZnSnS₄ (CZTS) nanocrystal (NC) layers were deposited successfully by electrophoretic deposition (EPD) on molybdenum and fluorine doped tin oxide coated glass substrates. This approach combines a non-vacuum coating technique known for its industrial eligibility to a solar absorber material consisting solely of non-toxic and earth abundant elements. CZTS NC layers with thicknesses between 200 nm and 1.5 μm were formed in 0.5 to 1 min while the NC dispersion, consisting of organic solvents, depleted entirely. Therefore the layer thickness can be controlled by varying the concentration of NCs in dispersion. Scanning electron microscopy micrographs show compact and homogeneous films. The layers were analyzed by grazing incidence X-ray diffraction, Raman analysis. Optical properties were probed by UV-vis spectroscopy. The dependence of dispersion composition and applied voltage on deposition dynamics and duration was analyzed by the use of an optical monitoring setup. The results open up a route of low cost CZTS thin film fabrication with reduced chemical contamination, fast layer deposition and high raw material use.