Passivating contacts created via a thin interfacial oxide and a highly doped polysilicon layer, e.g., the TOPCon technology, are on the verge of being implemented in solar cell mass production. Investment decisions rely on R&D to identify the most promising implementation option, meaning a trustworthy roadmap based on predicted performance gains. This article shows how to thoroughly quantify the performance potential via numerical simulation, focusing on an evolutionary upgrade of a busbarless p-type bifacial passivated emitter rear cell (PERC) technology. We specifically highlight the need to consider not only the electrical gains of passivating contacts, but also the associated optical losses due to parasitic absorption in the polysilicon layers for front and rear illumination. The influence of free-carrier absorption in polysilicon on the solar cell optics is characterized on experimental test structures in order to verify our optical simulation model. Introducing TOPCon fully at the rear and also locally aligned to the front fingers can boost the PERC efficiency by approximately 1%abs. The final device is strongly limited by losses in the p-type c-Si bulk and phosphorus-doped front emitter. Consequently, the presented evolutionary TOPCon upgrades may well be of increased relevance for future improved p-PERC cells, as an alternative to the current focus on n-type TOPCon cells with boron emitter.

中文翻译：

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TOPCon PERC 太阳能电池进化升级的效率路线图：寄生吸收的影响

通过薄的界面氧化物和高度掺杂的多晶硅层创建的钝化触点，例如 TOPCon 技术，即将在太阳能电池大规模生产中实施。投资决策依赖于研发来确定最有希望的实施选项，这意味着基于预测的性能收益的值得信赖的路线图。本文展示了如何通过数值模拟彻底量化性能潜力，重点介绍无母线 p 型双面钝化发射极后电池 (PERC) 技术的进化升级。我们特别强调不仅需要考虑钝化触点的电增益，还需要考虑由于多晶硅层中的寄生吸收导致的相关光学损失，用于前照和后照。多晶硅中自由载流子吸收对太阳能电池光学的影响在实验测试结构上进行了表征，以验证我们的光学模拟模型。在后部完全引入 TOPCon 并与前指局部对齐可以将 PERC 效率提高大约 1% abs。最终器件受到 p 型 c-Si 块体和掺磷前发射极损耗的强烈限制。因此，所提出的进化 TOPCon 升级很可能与未来改进的 p-PERC 电池更相关，作为当前关注具有硼发射体的 n 型 TOPCon 电池的替代方案。在后部完全引入 TOPCon 并与前指局部对齐可以将 PERC 效率提高大约 1% abs。最终器件受到 p 型 c-Si 块体和掺磷前发射极损耗的强烈限制。因此，所提出的进化 TOPCon 升级很可能与未来改进的 p-PERC 电池更相关，作为当前关注具有硼发射体的 n 型 TOPCon 电池的替代方案。在后部完全引入 TOPCon 并与前指局部对齐可以将 PERC 效率提高大约 1% abs。最终器件受到 p 型 c-Si 块体和磷掺杂前发射极损耗的强烈限制。因此，所提出的进化 TOPCon 升级很可能与未来改进的 p-PERC 电池更相关，作为当前关注具有硼发射体的 n 型 TOPCon 电池的替代方案。