Effect of cadmium chloride treatment on CdS buffer layer and its impact on growth of CdTe layer: An experimental and numerical studies

This paper focuses on the study of the structural, morphological, electrical and optical properties of the pristine and CdCl2 treated CdS buffer layer as well as of the CdTe thin films deposited on the pristine and CdCl2 treated CdS buffer layers. CdS buffer layers have been grown by Chemical bath deposition technique and CdTe absorber layers have been deposited by thermal evaporation method. These thin films have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Hall Effect measurements and UV–Vis spectroscopy. XRD analysis demonstrated that there is an increase in the intensities of peaks as well as crystallite size of the CdCl2 treated CdS buffer layer as well as of the CdTe thin films deposited on them. SEM analysis illustrated there is improvement in grain size and compactness of CdCl2 treated CdS buffer layer as well as that of the CdTe thin films deposited on them than that of the pristine samples. From the optical and electrical properties analysis it is observed that there is enhancement in absorbance and decrement in bandgaps with increased values of carrier concentration, mobility, and conductivity of the CdCl2 treated CdS buffer layer and the CdTe thin films deposited on the CdCl2 treated CdS buffer layer respectively. Finally, glass/FTO/CdS/CdTe and glass/FTO/CdS/CdCl2/CdTe solar cells were numerically simulated by SCAPS using the experimental data obtained in the present study to extract J-V curve and the influence of temperature and defect density on the J-V characteristics were also studied. The extracted parameters are Voc = 1.00V, Jsc = 30.41 m A/cm2, F·F. = 85.31% and ƞ = 25.94% of the glass/FTO/CdS/CdCl2/CdTe solar cell. Hence these solar cells can be fabricated experimentally as their suitability has been proved through numerically simulated results.