Optoelectrical impact of alternative window layer composition in CdTe thin film solar cells performance

This study investigates the integrability of different alternatives of cadmium sulfide (CdS), namely, oxygenated cadmium sulfide (CdS:O) and cadmium zinc sulfide (CdZnS) as the potential window layers in CdTe thin film solar cells using SCAPS-1D and experimental fabrication. The performance parameters such as open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), conversion efficiency (eta), and quantum efficiency (QE) have been examined for cells with different carrier concentration and series resistance (Rs) of window layer materials. Calculation results shows that the incorporation of oxygen (CdS:O) with series resistance (Rs <= 1E-1 Omega.cm(2)) and minimum carrier concentration of 10(16) cm(-3) contributes in optimum band alignment that enhances photo-current collection from both short and long wavelength regions compared to baseline CdS/ CdTe solar cell. Moreover, the performance of the proposed cells has been improved in terms of QE, Jsc, Voc, and FF upon insertion of novel CdZnS layer. However, carrier recombination increases the saturation current density for CdZnS resulting in unstable performance. Consequently, upon insertion of CdS:O window layer, conversion efficiency enhancement is observed with Jsc (29.10 mA.cm(-2)), Voc (0.889 V) and FF (70.39%). The proposed window materials are deposited using RF-sputtering method and the experimental results are incorporated in simulation to validate the findings.

Automated summary

This study investigates the integrability of different alternatives of CdS as the potential window layers in CdTe thin film solar cells. The results show that the incorporation of oxygen and CdZnS enhances the photo-current collection and improves the performance of the cells. However, carrier recombination affects the stability of the CdZnS layer. The proposed CdS:O window layer improves the conversion efficiency, Jsc, Voc, and FF. The experimental results validate the findings of the simulation.