Unveiling the complex interplay between CdTe film thickness and CdCl2 treatment of CdTe films for Solar Cell device

Abstract

The present work provides an in-depth analysis into the intricate interplay between the film thickness and CdCl₂ treatment on the Cadmium Telluride (CdTe) films. This investigation utilized strategically designed set of samples that vary from each other in terms of film thickness and CdCl₂ treatment. The four sets of samples having device structures: i) glass/FTO/CdS/CdTe, ii) glass/FTO/CdS/CdTe/CdCl₂, iii) glass/FTO/CdS/CdTe/CdCl₂/CdTe, and iv) glass/FTO/CdS/CdTe/CdCl₂/CdTe/CdCl₂ are fabricated. Initially, the CdTe films are analyzed by X-ray diffraction (XRD), Scanning electron microscope (SEM), Atomic force microscopy (AFM), Hall Effect measurements, and UV–Vis spectroscopy. XRD analysis revealed that CdTe films exhibited polycrystalline structure with a cubic phase displaying prominent (111) peak of orientation. However, peak intensities of samples varied with respect to film thickness and CdCl₂ treatment in the CdTe films. Similarly, from the SEM and AFM results of CdTe films, it was noticed that the surface morphology and roughness differed with respect to film thickness and CdCl₂ treatment. The electrical and optical characterizations illustrated that carrier concentration as well as conductivity and bandgap of samples varied with respect to film thickness and CdCl₂ treatment of CdTe thin films. The glass/FTO/CdS/CdTe/CdCl₂/CdTe configuration showed impressive structural, morphological, topological, and electrical results as compared to other configurations and a device of nearly 8% efficiency was obtained. J–V curves of this all the configurations have been studied in detail. Therefore, these results indicate that film thickness and CdCl₂ treatment play a vital function in improving potential of CdTe solar cells.