Kesterite solar cells show great potential for sustainable photovoltaic technology, attributed to their excellent semiconductor properties and earth abundant composition. However, undesirable band bending at the grain boundaries (GBs) in Cu2ZnSn(S,Se)4 (CZTSSe) films induces serious carrier recombination because of inhomogeneous distribution of S and Se in the grain interiors (GIs) and at GBs, which results in large open-circuit voltage deficit and overall poor performance of CZTSSe solar cells. Here, a robust hydrothermal sulfurization design has successfully inverted the band bending at the GBs, with advanced cathodoluminescence measurement confirming the transition of carrier collection pathways from the GBs to the GIs, thereby achieving efficient carrier collection within the GIs. Simultaneously, this design has effectively passivated the non-radiative recombination in the GIs, smoothing the way for carrier collection. Ultimately, a 13.7 % efficiency CZTSSe solar cell with 44 % improvement is realized by this process. This study discloses that reversing the band bending at GBs is practical to tailor the carrier collection, and thus pave the pathway for high-efficient photoelectronic devices.

中文翻译：

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晶界处的反向带弯曲可实现高效 Cu2ZnSn（S，Se）4 太阳能电池


Kesterite 太阳能电池显示出可持续光伏技术的巨大潜力，这归功于其出色的半导体特性和丰富的地球成分。然而，由于 S 和 Se 在晶粒内部 （GIs） 和 GB s中的分布不均匀，Cu2ZnSn（S，Se）4 （CZTSSe） 薄膜中晶界 （GB） 处不需要的带弯曲会诱导严重的载流子复合，从而导致较大的开路电压损耗和 CZTSSe 太阳能电池的整体性能不佳。在这里，一种稳健的水热硫化设计成功地反转了 GB 处的谱带弯曲，先进的阴极发光测量证实了载流子收集途径从 GB 到 GI 的转变，从而在 GI 内实现高效的载流子收集。同时，这种设计有效地钝化了 GIs 中的非辐射复合，为载流子收集铺平了道路。最终，通过此过程实现了效率为 13.7% 的 CZTSSe 太阳能电池，性能提高了 44%。本研究揭示了反转 GB 处的带弯曲对于定制载流子集合是可行的，从而为高效光电器件铺平了道路。