Organic ammonium salts are extensively utilized for passivating surface defects in perovskite films to mitigate trap-assisted nonradiative recombination. However, the influence of alkyl chain length on the molecular orientation and spatial steric hindrance of ammonium salt remains underexplored, hindering advancements in more effective passivators. Here, a series of organic ammonium salts is reported with varying alkyl chain lengths to passivate surface defects and optimize band alignment. It is revealed that long alkyl chains promote parallel molecular orientation on the perovskite surface, thereby reinforcing interaction with surface defects, whereas excessive chain length introduces steric hindrance, weakening anion-perovskite interactions. Nonylammonium acetate (NAAc) with optimal chain length achieves the ideal balance between chemical interactions, resulting in superior passivation. Through NAAc passivation, high-performance inverted perovskite solar cells (PSCs) and modules are achieved, with power conversion efficiencies (PCE) of 25.79% (certified 25.12%) and 19.62%, respectively. This marks a record PCE for inverted PSCs utilizing vacuum flash technology in ambient conditions. Additionally, the NAAc-passivated devices retain 91% of their initial PCE after 1200 h of continuous maximum power point operation. This work offers new insights into the interplay between molecular orientation and steric hindrance, advancing the design of high-performance PSCs.

中文翻译：

---

铵盐钝化剂中烷基链长度诱导的取向和空间位阻的协同调制对高性能倒置钙钛矿太阳能电池和组件


有机铵盐广泛用于钝化钙钛矿薄膜中的表面缺陷，以减轻陷阱辅助的非辐射复合。然而，烷基链长度对铵盐分子取向和空间空间位阻的影响仍未得到充分探索，阻碍了更有效钝化剂的进步。在这里，报道了一系列具有不同烷基链长度的有机铵盐，以钝化表面缺陷并优化条带对齐。结果表明，长烷基链促进钙钛矿表面的平行分子取向，从而加强与表面缺陷的相互作用，而过长的链会引入空间位阻，削弱阴离子-钙钛矿相互作用。具有最佳链长的壬基乙酸铵 （NAAc） 实现了化学相互作用之间的理想平衡，从而实现了卓越的钝化效果。通过 NAAc 钝化，实现了高性能的倒置钙钛矿太阳能电池 （PSC） 和组件，功率转换效率 （PCE） 分别为 25.79%（认证为 25.12%）和 19.62%。这标志着在环境条件下利用真空闪蒸技术的倒置 PSC 创下了创纪录的 PCE。此外，NAAc 钝化器件在连续最大功率点运行 1200 小时后仍保留其 91% 的初始 PCE。这项工作为分子取向和空间位阻之间的相互作用提供了新的见解，推进了高性能 PSC 的设计。