Influence of Deposition Conditions on Properties of All Sputtered CdS/CdTe Thin-Film Solar Cells

Abstract

The effects of deposition conditions, such as substrate temperature and CdCl2 post treatments, on the structural and optical properties of CdTe films were investigated. In addition, CdS/CdTe thin-film solar cells were fabricated by an all-sputtering process, and their photovoltaic characteristics were studied. The CdTe films had a polycrystalline, cubic structure with a preferred orientation of the [1 1 1] direction parallel to the substrate surface, regardless of the substrate temperature. As the substrate temperature increased, the crystallinity of CdTe films improved. The grain size of the CdTe films increased after CdCl2 post treatment. In addition, the optical band gap increased with the substrate temperature. The conversion efficiency of the CdS/CdTe solar cell improved at higher substrate temperatures. The maximum efficiency, 9.23%, was obtained at a substrate temperature of 400 degrees C, with an open-circuit voltage (V(oc)) of 0.78 V, a short-circuit current density (J(sc)) of 20.4 mA/cm2, and a fill factor of 0.58.