This article investigates the impact of the back-surface-field (BSF) thickness variation within a local aluminum contact on the performance of passivated emitter and rear contact solar cells. A significant difference of BSF thickness between contact endings and the center of dash-shaped contacts is verified experimentally by a comprehensive statistical analysis using scanning electron microscopy. The impact of local BSF thickness differences on the cell performance is studied with 3-D technology computer-aided design (TCAD) device simulations. Several device parameters such as BSF thicknesses, the doping concentration in the BSF profile at rear contacts, or the metallized area fraction at the cell rear side are varied. Our simulation study shows that the open-circuit voltage is mainly affected by locally reduced BSF thicknesses, resulting in an efficiency loss up to 0.14% _abs or 0.84% _abs , respectively, if an area fraction of 1% or 20% within a local contact has reduced BSF thicknesses. This effect can be minimized either by reducing the metallized area fraction at the cell rear side or by increasing the doping concentration in the BSF profile at aluminum rear contacts. In addition, we demonstrate that the 3-D simulations can be approximated with 2-D simulations by applying a single doping profile with an average BSF thickness, calculated with the harmonic mean.

中文翻译：

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局部背表面场厚度变化对 PERC 太阳能电池性能的影响


本文研究了局部铝触点内的背表面场 (BSF) 厚度变化对钝化发射极和后接触太阳能电池性能的影响。通过使用扫描电子显微镜进行综合统计分析，实验验证了接触端部和虚线形接触中心之间 BSF 厚度的显着差异。通过 3D 技术计算机辅助设计 (TCAD) 设备模拟研究了局部 BSF 厚度差异对电池性能的影响。多个器件参数（例如 BSF 厚度、背面接触处 BSF 分布的掺杂浓度或电池背面的金属化面积分数）是不同的。我们的模拟研究表明，开路电压主要受到局部减小的 BSF 厚度的影响，如果局部接触内的面积分数为 1% 或 20%，则效率损失分别高达 0.14% _abs或 0.84% _abs减少了 BSF 的厚度。通过减少电池背面的金属化面积分数或增加铝后触点处 BSF 分布的掺杂浓度，可以最大限度地减少这种影响。此外，我们还证明，通过应用具有平均 BSF 厚度（用调和平均值计算）的单一掺杂分布，可以用 2-D 模拟来近似 3-D 模拟。