A world record conversion efficiency of 26.81% has been achieved recently by LONGi team on a solar cell with industry-grade silicon wafer (274 cm², M6 size). An unparalleled high fill factor (FF) of up to 86.59% has also been certified in a separated device. The theoretical FF limit has been predicted to be 89.26%, while the practical FF is far below this limit for a prolonged interval due to the constraints of recombination (i.e., SRH recombination) and series resistance. The ideality factor (m) in the equivalent circuit of silicon solar cells is consistently ranging from 1 to 2 and rarely falls below 1, resulting in a relatively lower FF than 85%. Here, this work complements a systematic simulation study to demonstrate how to approach the FF limit in design of silicon solar cells. Firstly, a diode component with an ideality factor equal to 2/3 corresponding to Auger recombination is incorporated in the equivalent circuit for LONGi ultra-high FF solar cell; Secondly, an advanced equivalent circuit is put forward for comprehensive analysis of bulk recombination and surface recombination on the performance, in which specific ideality factors are directly correlated with various recombination mechanisms exhibiting explicit reverse saturation current density (J₀). Finally, we evaluate precisely the route for approaching theoretical FF in practical solar cell fabrication based on electrical design parameters using the developed model.

中文翻译：

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揭示硅太阳能电池获得高填充因子的机制

^{近日，隆基团队在工业级硅片（274 cm 2}，M6尺寸）太阳能电池上取得了26.81%的转换效率世界纪录。高达 86.59% 的无与伦比的高填充因子 ( FF ) 也已在单独的设备中得到认证。理论FF极限被预测为89.26%，而由于复合（即SRH复合）和串联电阻的限制，实际FF在较长时间内远远低于该极限。硅太阳能电池等效电路中的理想因子（m）始终在1到2之间，很少低于1，导致FF相对低于85%。在这里，这项工作补充了系统模拟研究，以演示如何接近硅太阳能电池设计中的FF极限。首先，在隆基超高FF太阳能电池的等效电路中加入了与俄歇复合相对应的理想因子等于2/3的二极管组件；其次，提出了一种先进的等效电路来综合分析体复合和表面复合对性能的影响，其中特定的理想因子与表现出显式反向饱和电流密度（J ₀）的各种复合机制直接相关。最后，我们使用开发的模型根据电气设计参数精确评估在实际太阳能电池制造中接近理论FF的路线。