Modeling of photoconverter parameters based on CdS/porous-CdTe/CdTe heterostructure

This article presents a comprehensive study of the fabrication and modeling of a CdS/porous-CdTe/CdTe heterostructure aimed at improving solar cell efficiency. The research focuses on two critical processes: the electrochemical etching for producing porous-CdTe substrates and the chemical surface deposition method for applying CdS films. The structural and optical characteristics of the fabricated heterostructure were analyzed using SEM and EDAX methods, confirming the formation of a continuous CdS layer over a porous-CdTe layer. The thickness of the porous-CdTe and CdS layers was 1.0 and 2.0 μm, respectively. The obtained thick values of the manufactured structure were used to model the CdS/porous-CdTe/CdTe heterostructure in the PC1D-program in order to find the optimal solar cell parameters. The photoconverter current-voltage curve was obtained from the PC1D-program. The theoretically calculated efficiency was 21.6%. The study further explored the impact of varying the thickness of the CdS window layer and the porous-CdTe buffer layer on photoconverter performance. The efficiency of the CdS/porous-CdTe/CdTe photoconverter reaches maximum values at a thickness of 2.3-2.4 μm and 1.9 μm for CdS and porous-CdTe layers, respectively. Additionally, the buffer layer's porosity enhanced light absorption, contributing to higher carrier generation rates. In order to increase the CdS/porous-CdTe/CdTe photoconverter efficiency, the single-layer and double-layer antireflective coatings used, which are most often in the CdS/CdTe solar cells production, was investigated. To further optimize the photoconverter, anti-reflective coatings were investigated using the matrix method. The results showed that the best reflectance is observed for the ITO/ZnO double anti-reflective coating. The solar cell efficiency with this coating was 22.8% at 50/30 nm thicknesses. Additional research in the modifying the porosity of the substrates and its effect on the photoconverter characteristics may lead to the discovery of new opportunities increasing their efficiency and stability. The findings underscore the potential of CdS/porous-CdTe/CdTe heterostructures as efficient photovoltaic devices.