Zinc-induced changes on structural pathways, optical parameters, optical constants extracted by Kramers-Kronig Formulas, Photoluminescence Spectra and photovoltaic characteristics of n-Cd50-xZnxS50/i-AgSe/p-Si solar cells

In highlighted our study's scenarios, the importance of using a buffer layer of AgSe between an absorbent silicon substrate and a Cd50-xZnxS50 window layer with different Zn content with (x = 0, 10, 20, 30, 40, and 50 wt%) was discussed. The significant influence of the window layer on the properties of fabricated designs: (front electrode) Nickel (Ni)/n-Cd50-xZnxS50/i-AgSe/p-Si/(pt), platinum (back electrode) was also studied. This work devoted a large portion of its parts to investigate the structural, optical, photoluminesce, and thermopower properties of the CdZnS window layer to highlight the rationale for its application in the solar cells fabricated in this study. Pure phases of CdS and ZnS were confirmed through XRD and SEM analysis for the CdZnS window layers. Based on Tauc and Urbach's relationships, the optical parameters (bandgap energy Eg, tail energy Ee) were extracted. The optical constants (refractive index n, absorption index k) were calculated via the Kramers-Kronig formulas. In the visible region at 300-800 nm, the CdZnS thin layers showed a sharp peak in photoluminescence PL study results. The current density-voltage (J-V) characteristics in dark and illumination conditions were discussed. The highest power conversion efficiency (PCE) was for the last window layer. Thus, this layer was appropriate for the fabricated solar cells to obtain good photovoltaic properties.