Development of CdTe thin film solar cells for military applications

This experiment reports the study on CdS/CdTe thin film solar cells for military application. In this work, CdS/CdTe thin film solar cell has been heat-treated with various device structures and chemical treatments in order to activate the properties of CdTe for optimum solar cell device performance. These treatments are such as CdCl2 treatment, CdCl2+CdF2 treatment and CdCl2+CdF2+GaCl2 treatment. These samples were then characterised using XRD, UV-Vis spectroscopy and DC measurements for their structural, optical and electrical properties. XRD characterisations show the presence of fluoride in ppm in the treatment demonstrated a rearrangement in the orientation of the crystallite and increased the (220) and (311) peaks to form a polycrystalline structure. PEC measurements demonstrated that all of CdTe films become p-type after being treated with CdCl2 and CdCl2+CdF2. Contrary, CdTe treated with CdCl2+CdF2+GaCl3 changes the p-CdTe at Vg≥706 mV into n-type due to the effect of Ga which dissolved the Te precipitations to the surface.The optimum condition was obtained when the samples annealed at 450°C in the presence of CdCl2+CdF2. Further study demonstrates that the best solar cell efficiency is obtained when using CdTe thin films treated with CdCl2+CdF2.