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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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Device Characteristics of Bandgap Tailored 10.04% Efficient CZTSSe Solar Cells Sprayed from Water Based Solution
摘要： Diverse S/(S+Se) ratio of Cu2ZnSn(Sx,Se1–x)4 (CZTSSe) thin film solar cells fabricated by water based spray pyrolysis approach. By fine tuning the S/(S+Se) ratio, base CZTSSe device efficiency has significantly improved from 7.02% to 10.04% by minimizing the Voc deficit up to 616 mV and increasing FF from 56.42% to 62.38%. As S/(S+Se) ratio was increased from 0 to 0.4, surface compactness was observed to be improved with slightly decreased grain size, which increased shunt resistance and resultantly increased fill factor. However, S-alloying more than S/(S+Se)=0.4, grain size was too much decreased and had detrimental effect on device performance. To deeply understand the role effect of S/(S+Se) ratio, detailed spectroscopic analysis performed with admittance spectroscopy (AS), temperature dependent current-voltage characteristic (J-V-T), time-resolved photoluminescence (TRPL) and Raman depth profiling. Experimental results revealed that the different power conversion efficiency (PCE) limiting factors were developed with various S/(S+Se) ratio. High density of deep defect states generated with S/(S+Se) ≥ 40% content and larger conduction band offset observed with red kink were formed in the Se/(S+Se) ≥ 80% content. Hence, in order to get high efficient CZTSSe solar cell, fine tuning of S/(S+Se) ratio is necessary.
关键词： Aqueous solution,Defect characterization,Spray deposition,Chalcogen ratio,Photovoltaic properties,CZTSSe thin films
更新于2025-09-12 10:27:22
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Solution-processed method for high-performance Cu2ZnSn(S,Se)4 thin film solar cells and its characteristics
摘要： Kesterite Cu2ZnSn(S,Se)4 (CZTSSe) has attracted much attention as an ideal absorber material for thin film solar cells. Solution deposition methods provide a crucial approach for lowering the fabricating price of CZTSSe based photovoltaic devices. Here, a low-cost and robust ethanol/thioglycolic acid/1-butylamine ternary solutions method was developed to fabricate the CZTSSe solar cells. Characterization was performed using XRD, Raman, and C–V, which showed that the material fabricated by this method expressed high-phase purity, suitable carrier concentration, and large depletion width, and those features are vital to high efficiency photovoltaic devices. Hence, based on this high quality CZTSSe absorbed layer, photovoltaic device with a power conversion efficiency (PCE) as high as 9.71% was achieved. The PCE can be further enhanced through passivating with alkali metal and optimizing the device fabrication conditions, making this method much promising for lowering the manufacturing cost of kesterite solar cells. Additionally, this approach is full of application prospect for other burgeoning photovoltaic absorber materials which could dramatically reduce the cost of solar electricity.
关键词： Thin film,CZTSSe,Kesterite,Solution process,Solar cells
更新于2025-09-11 14:15:04
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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