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Towards highly efficient thin-film solar cells with a graded-bandgap CZTSSe layer
摘要： A coupled optoelectronic model was implemented along with the differential evolution algorithm to assess the efficacy of grading the bandgap of the Cu2ZnSn(SξSe1?ξ)4 (CZTSSe) layer for enhancing the power conversion efficiency of thin-film CZTSSe solar cells. Both linearly and sinusoidally graded bandgaps were examined, with the molybdenum backreflector in the solar cell being either planar or periodically corrugated. Whereas an optimally graded bandgap can dramatically enhance the efficiency, the effect of periodically corrugating the backreflector is modest at best. An efficiency of 21.74% is predicted with sinusoidal grading of a 870-nm-thick CZTSSe layer, in comparison to 12.6% efficiency achieved experimentally with a 2200-nm-thick homogeneous CZTSSe layer. High electron-hole-pair generation rates in the narrow-bandgap regions and a high open-circuit voltage due to a wider bandgap close to the front and rear faces of the CZTSSe layer are responsible for the high enhancement of efficiency.
关键词： optoelectronic optimization,Bandgap grading,thin-film solar cell,earth-abundant materials,CZTSSe solar cell
更新于2025-09-16 10:30:52
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CuZnSn(SxSe1-x)4 Solar Cell Prepared by the Sol-Gel Method Following a Modified Three-Step Selenization Process
摘要： In current work, Cu2ZnSn(S,Se)4 thin films have been prepared by the sol-gel method based on dimethyl sulfoxide solution followed by a modified three-step selenization process. The key process of this method is to divide the Se evaporation and annealing into two different stages: employ a thermal cracking Se source in the Se evaporation stage and an above-atmospheric pressure in the annealing process. The morphological, structural, elemental distributional, and photovoltaic properties of Cu2ZnSn(S,Se)4 thin films prepared with the three-step selenization process were systematically investigated. It was found that through this modified selenization process, the formations of secondary phases (ZnSe, CuSnSe3) and a fine-grain bottom layer, which usually exists in the traditional one-step selenization process, were effectively suppressed. These improvements could further reduce the carrier recombination and improve the solar cell performance. The best solar cell is obtained with a short-circuit current density of 28.16 mA/cm2, open-circuit voltage of 404.91 mV, fill factor of 62.91%, and a power conversion efficiency of 7.17% under air mass 1.5 (100 mW/cm2) illumination.
关键词： selenization,thermal cracking Se,CZTSSe solar cell,secondary phases,sol-gel method,above-atmospheric pressure
更新于2025-09-11 14:15:04