Effect of CdS Layer Thickness on Thermally Evaporated-CdS/CdTe Solar Cell Efficiency

CdS thin films were deposited with different thicknesses on Fluorine-doped Tin Oxide glass substrates by vacuum thermal evaporation technique. Vacuum annealed CdS thin films were characterized for structural, optical, topological, and electrical properties. The optical bandgap of CdS varied between 2.39 and 2.43 eV with increasing thickness. Profile fit, Pawley Refinement technique, and Rietveld Refinement technique were used to determine structural properties and phase distribution. The influence of thickness on the photoelectrochemical (PEC) cells was discussed with current-voltage and Mott-Schottky analysis. The thermal evaporation technique was used to deposit the CdTe layer on top of the CdS layer to fabricate CdS/CdTe solar cells. The highest efficiency (4.43%) and external quantum efficiency (71%) were observed for the cells fabricated with CdS film thickness of 210 nm. SCAPS-1D simulation was used to confirm the variation further.