An unnatural hygroscopic property of nonhygroscopic nicotinic acid (NA) is demonstrated by tuning the intermolecular distance. After addition of NA into methylammonium lead iodide, (MAPbI₃) NA molecules are preferentially aligned on the interface of the three-dimensional (3D) MAPbI₃ crystal structure by a hydrogen bond. This unique behavior allows NA to be used as a versatile additive to improve the water durability of MAPbI₃. After exposure under a high humidity atmosphere (RH 100%, 35 °C), MAPbI₃ films with NA exhibited self-healing phenomena against moisture while bare MAPbI₃ rapidly lost its own intrinsic property. Density functional theory (DFT) calculations were conducted to reveal how H₂O molecules can effectively be absorbed by NA according to its planar molecular density. Also, further optimization of photovoltaic device performances was carried out by investigating the relationship between NA concentration and additive alignment.

中文翻译：

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通过重构分子密度实现烟酸的非自然吸湿性：自修复卤化物钙钛矿

通过调节分子间距离证明了非吸湿性烟酸 (NA) 的非自然吸湿性。在将 NA 添加到甲基碘化铅中后，(MAPbI ₃ ) NA 分子通过氢键优先排列在三维 (3D) MAPbI ₃晶体结构的界面上。这种独特的行为使 NA 可用作通用添加剂，以提高 MAPbI ₃的耐水性。在高湿度环境（RH 100%，35°C）下暴露后，具有 NA 的MAPbI ₃薄膜表现出对水分的自修复现象，而裸露的 MAPbI ₃迅速失去其固有特性。进行密度泛函理论 (DFT) 计算以揭示 H ₂O分子可以根据其平面分子密度被NA有效吸收。此外，通过研究 NA 浓度与添加剂排列之间的关系，进一步优化了光伏器件的性能。