Carrier-selective contact is a fundamental issue for solar cells. For silicon heterojunction (SHJ) solar cells, it is important to improve hole transport because of the low doping efficiency of boron in amorphous silicon and the barrier stemming from valence band offset. Here, we develop a carbon dioxide (CO₂) plasma treatment (PT) process to form dipoles and defect states. We find a dipole moment caused by longitudinal distribution of H and O atoms. It improves hole transport and blocks electron transport and thus suppresses carrier recombination. In the meantime, the CO₂ PT process also results in defect states, which reduce passivation performance but improve hole hopping in the intrinsic amorphous layer. As a balance, an appropriate CO₂ PT process at the i/p interface increases fill factor and power conversion efficiency of SHJ solar cells. We emphasize, based on sufficient evidences, this work finds a distinct role of the CO₂ plasma in SHJ solar cells opposed to reported mechanisms.

中文翻译：

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CO2 等离子体引起的偶极子和缺陷改善了硅太阳能电池的载流子传输

载流子选择性接触是太阳能电池的一个基本问题。对于硅异质结（SHJ）太阳能电池，由于非晶硅中硼的掺杂效率低以及价带偏移引起的势垒，改善空穴传输非常重要。在这里，我们开发了一种二氧化碳（CO ₂）等离子体处理（PT）工艺来形成偶极子和缺陷态。我们发现了由 H 和 O 原子的纵向分布引起的偶极矩。它改善空穴传输并阻止电子传输，从而抑制载流子复合。同时，CO ₂ PT工艺也会产生缺陷态，这会降低钝化性能，但会改善本征非晶层中的空穴跳跃。作为平衡，i/p 界面处适当的 CO ₂ PT 工艺可提高 SHJ 太阳能电池的填充因子和功率转换效率。我们强调，基于足够的证据，这项工作发现了CO ₂等离子体在SHJ太阳能电池中的独特作用，与报道的机制相反。