Variations in photovoltaic parameters of CdTe/CdS thin film solar cells by changing the substrate for the deposition of CdS window layer

Herein, we report on the variation in photovoltaic (PV) parameters of CdTe/CdS thin-film solar cells fabricated by depositing Cadmium sulfide (CdS) window layers on soda lime, indium doped tin oxide (ITO), fluorine-doped tin oxide (FTO) coated glass substrates by chemical bath deposition (CBD) technique. X-ray diffraction (XRD) patterns confirmed the cubic crystalline structure of the deposited CdS films and the highest diffraction intensity is observed in the film deposited on the FTO substrate. The scanning electron microscopy (SEM) images confirmed the homogenous, crack-free, and smooth nature of the films. The surface roughness values of the CdS films deposited on soda-lime, ITO, and FTO substrates were found to be 35.87, 27.49, and 14.32 nm, respectively. The band-gap values of the CdS films estimated from Tauc's plots are found to be in the range of 2.27–2.33 eV. The strong blue and green bands in PL spectra are found to peak at 560 nm. The peaks observed in the Fourier transform infrared (FT-IR) spectra are corresponding to C-S, Cd-S, and S-C-N vibrations. To fabricate a CdTe/CdS cell, the CdTe layer is deposited on the ITO-CdS and FTO-CdS layers separately. A back contact of silver is pasted on the top layer to complete the solar cell structure and the variations in photovoltaic (PV) parameters were recorded and analyzed. The efficiencies of CdTe/CdS cells fabricated with ITO-CdS and FTO-CdS window layers were found as 8.47% and 9.65%, respectively.