Numerical Simulation and Performance Enhancement of CZTS Thin Film Solar Cells

The development of thin-film solar cells allows researchers to evaluate different materials in order to improve the efficiency of cell conversion. This is particularly relevant for the third generation of solar photovoltaic cells, which incorporate layer materials at the nano- and micrometre-scale, avoiding non-toxic and earth-abundant materials with reduced manufacturing costs. In recent years, scientists have focused their studies on the lowest-cost and most stable materials, such as kesterite, based on the following elements: copper, zinc, tin, and sulfur (CZTS). It's one of the most efficient absorbing material layers in thin-film solar cells, with a direct bandgap (1.38-2.0 eV) and a high absorption coefficient (∼ 104 cm – 1). CZTS has tremendous potential due to its earth abundance, non-toxicity, and low production costs compared to other thin film materials. However, several challenges still exist regarding the control of secondary phases, compositional homogeneity, electronic defects, and instability issues during fabrication that limit the efficiency of CZTS-based solar cells and have yet to be overcome. In this paper, we implement a mathematical model of a heterojunction CdS-CZTS thin film solar cell. Hence, the output performance of solar cells can be evaluated by varying the material, parameters, dimensional ratios, and other variables in the cells; essentially,the conversion efficiency is given at a value of η = 12.79 % results of simulations using Matlab Simulink software. The improved conversion efficiency obtained through our simulation study falls within the range of experimental values achieved for this type of thin film solar cell design, as demonstrated by the laboratory's record measured efficiency of around 12.6 % for a similar heterojunction cell based on CZTS reported by Wei Wang et al., while the theoretical maximum conversion efficiency for an ideal CZTS-based solar cell is estimated at 32.4 % according to the Shockley Queisser limit. As our simulated efficiency value is close to measured experimental values while still significantly below the theoretical limit, this suggests that further efficiency improvements may still be achievable through material property and cell design optimizations.