Cadmium selenide (CdSe) thin films were grown on borosilicate glass substrates using the RF magnetron sputtering method. In this study, CdSe thin film was deposited at a deposition temperature in the range of 25 °C to 400 °C. The influence of deposition or growth temperature on the structural, morphological, and opto-electrical properties of CdSe films was investigated elaborately to achieve a good-quality window layer for solar-cell applications. The crystal structure, surface morphology, and opto-electrical characteristics of sputtered CdSe films were determined using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–Vis spectrophotometry, and Hall effect measurement, respectively. The XRD results revealed the polycrystalline nature of CdSe, with a hexagonal structure having a strong preferential orientation toward the (002) plane. As evident from the FESEM images, the average grain size and surface morphology of the films were dependent on deposition temperatures. The carrier concentration was obtained as 10¹⁴ cm⁻³. The band gap in the range of 1.65–1.79 eV was found. The explored results suggested that sputtered CdSe thin film deposited at 300 °C has the potential to be used as a window layer in solar cells.

Even though substantial advances made in the device configuration of the frontal layers of the superstrate cadmium telluride (CdTe) solar cell device have contributed to conversion efficiency, unresolved challenges remain in regard to controlling the self-compensation and minority carrier recombination at the back contact that limits the efficiency. In this study, a SCAPS-1D simulator was used to analyze the loss mechanism and performance limitations due to the band-bending effect upon copper chloride treatment and subsequent Cu₂Te layer formation as the back contact buffer layer. The optimal energy bandgap range for the proposed back surface layer of Cu₂Te is derived to be in the range of 1.1 eV to 1.3 eV for the maximum conversion efficiency, i.e., around 21.3%. Moreover, the impacts of absorber layer’s carrier concentration with respect to CdTe film thickness, bandgap, and operational temperature are analyzed. The optimized design reveals that the acceptor concentration contributes significantly to the performance of the CdTe devices, including spectral response. Consequently, the optimized thickness of the CdTe absorber layer with a Cu-based back contact is found to be 2.5 µm. Moreover, the effect of temperature ranging from 30 °C to 100 °C as the operating condition of the CdTe thin-film solar cells is addressed, which demonstrates an increasing recombination tread once the device temperature exceeds 60 °C, thus affecting the stability of the solar cells.

The effect of a nontoxic chloride treatment on the crystallinity and optoelectrical characteristics of a CdSe thin film was studied. A detailed comparative analysis was conducted utilizing four molarities (0.01 M, 0.10 M, 0.15 M, and 0.20 M) of indium (III) chloride (InCl₃), where the results showed a notable improvement in CdSe properties. The crystallite size of treated CdSe samples increased from 31.845 nm to 38.819 nm, and the strain in treated films dropped from 4.9 × 10⁻³ to 4.0 × 10⁻³, according to XRD measurements. The highest crystallinity resulted from the 0.10 M InCl₃-treated CdSe films. The In contents in the prepared samples were verified by compositional analysis, and FESEM images from treated CdSe thin films demonstrated compact and optimal grain arrangements with passivated grain boundaries, which are required for the development of a robust operational solar cell. The UV-Vis plot, similarly, showed that the samples were darkened after treatment and the band gap of 1.7 eV for the as-grown samples fell to roughly 1.5 eV. Furthermore, the Hall effect results suggested that the carrier concentration increased by one order of magnitude for samples treated with 0.10 M of InCl₃, but the resistivity remained in the order of 10³ ohm/cm², suggesting that the indium treatment had no considerable effect on resistivity. Hence, despite the deficit in the optical results, samples treated at 0.10 M InCl₃ showed promising characteristics as well as the viability of treatment with 0.10 M InCl₃ as an alternative to standard CdCl₂ treatment.