ABSTRACT: Kesterite Cu2CoSnS4 thin film solar cells were synthesized and deposited on glass substrates at a bath temperature of 343K for 5 hours. The structural and optical properties of the films were studied using X-ray diffraction analysis and spectrophotometer measurements in the wavelength range from 400 – 1000nm i.e. within the ultraviolet, visible and NIR regions of electromagnetic spectrum. Our interests in this paper are on the effects of the concentrations of the precursor on the extinction coefficients and refractive indices of the thin films. The concentrations of cobalt (Co) had no defined relationships with the refractive indices of the film samples. Nevertheless, since the refractive indices of the film samples with cobalt concentrations of 0.2 – 0.4M are 0.541, 0.40 and 0.60 (which are below unity) respectively, these samples are good candidates for solar cells, as they are very good absorbing materials. The extinction coefficients are very low within the UV, visible and NIR regions of electromagnetic spectrum.
Keywords: Kesterite, concentration, extinction coefficients and refractive indices
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