One of the main causes of low performance of Cu2ZnSnS4 (CZTS) based thin film solar cells is its high recombination current. In this paper, the effects of the carrier concentration and recombination current in the CZTS thin film solar cells have been carefully scrutinized. In continue, for comparison and validation, two simulated structures based on the CZTS absorber layer have been reproduced and the influence of the absorber layer defects and carrier concentration has been analyzed. In this work, two different structures using p+-CZTS intermediate layer (between the CZTS absorber layer and Mo back-contact) and dual CZTS layer have been proposed and optimized to decrease recombination and extract the desired photovoltaic parameters. By using and optimizing these structures as p+pn junction, 15.62% and 19.08% efficiencies have been achieved in p+-CZTS intermediate layer and p+pn CZTS dual layer structures, respectively. The highest efficiency of dual absorber based solar cell is achieved when the carrier concentration of the p+-CZTS and p-CZTS absorber layers is 1 × 1018 cm−3 and 5 × 1015 cm−3, respectively. Moreover, the optimum thickness of the p+-CZTS and p-CZTS absorber layers in p+pn CZTS dual layer structure is 1 and 1.5 µm, respectively. Finally, the total recombination current density is reduced to 2.05 mA/cm2.

中文翻译：

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载流子浓度和复合电流对p+pn CZTS薄膜太阳能电池的影响

Cu2ZnSnS4（CZTS）基薄膜太阳能电池性能低下的主要原因之一是其高复合电流。在本文中，CZTS 薄膜太阳能电池中载流子浓度和复合电流的影响已被仔细审查。接下来，为了进行比较和验证，再现了两种基于 CZTS 吸收层的模拟结构，并分析了吸收层缺陷和载流子浓度的影响。在这项工作中，已经提出并优化了使用 p+-CZTS 中间层（在 CZTS 吸收层和 Mo 背接触之间）和双 CZTS 层的两种不同结构，以减少复合并提取所需的光伏参数。通过使用和优化这些结构作为 p+pn 结，15.62% 和 19。在 p+-CZTS 中间层和 p+pn CZTS 双层结构中分别实现了 08% 的效率。当 p+-CZTS 和 p-CZTS 吸收层的载流子浓度分别为 1 × 1018 cm-3 和 5 × 1015 cm-3 时，双吸收体太阳能电池的效率最高。此外，p+pn CZTS双层结构中p+-CZTS和p-CZTS吸收层的最佳厚度分别为1和1.5μm。最后，总复合电流密度降低到 2.05 mA/cm2。p+pn CZTS双层结构中p+-CZTS和p-CZTS吸收层的最佳厚度分别为1和1.5 µm。最后，总复合电流密度降低到 2.05 mA/cm2。p+pn CZTS双层结构中p+-CZTS和p-CZTS吸收层的最佳厚度分别为1和1.5 µm。最后，总复合电流密度降低到 2.05 mA/cm2。