Tin (Sn) perovskites as photovoltaic materials show great promise due to their suitable bandgaps and lower toxicity. However, various defects in Sn perovskites induce significant losses in devices. In this work, we report a strategy of dual-site passivation of Sn-related defects in lead-free Sn perovskite solar cells. We adopt ethylenediammonium halide salts (i.e., EDAI₂ and EDABr₂) as additives in Sn perovskite and find that both EDAI₂ and EDABr₂ can suppress Sn oxidation and passivate trap states, however, EDABr₂ works better than EDAI₂ in terms of passivating undesired grain boundaries and surface Sn vacancies, and reducing background hole density, due to the synergistic roles of EDA²⁺ cation and Br^- anion. Moreover, EDABr₂ exhibits more consummate passivation effect on Sn_I antisite defects as deep-level traps due to its larger electrostatic potential and shorter bonding length between -Br and -Sn. These enable great suppression of non-radiative recombination and enhancement of charge carrier transport. As a result, the best-performing EDABr₂-modified device achieves a power conversion efficiency of 14.23% with long-term durability of keeping ∼93% of its initial efficiency after storing for ∼4000 h and improved operational stability. Our work provides a promising approach to choose satisfactory passivators and fabricate efficient Sn perovskite solar cells.

锡（Sn）钙钛矿作为光伏材料由于其合适的带隙和较低的毒性而显示出巨大的前景。然而，Sn 钙钛矿中的各种缺陷会导致器件出现重大损失。在这项工作中，我们报告了无铅 Sn 钙钛矿太阳能电池中 Sn 相关缺陷的双位钝化策略。我们采用乙二铵卤化物盐（即EDAI ₂和EDABr ₂）作为Sn钙钛矿的添加剂，发现EDAI ₂和EDABr ₂都可以抑制Sn氧化和钝化陷阱态，但是EDABr ₂比EDAI _{2效果更好}由于EDA ²⁺阳离子和Br ^-阴离子的协同作用，在钝化不希望的晶界和表面Sn空位以及降低背景空穴密度方面。此外，EDABr ₂对作为深能级陷阱的Sn _I反位缺陷表现出更完美的钝化作用，因为它具有更大的静电势和更短的 -Br 和 -Sn 之间的键合长度。这些能够极大地抑制非辐射复合并增强电荷载流子传输。因此，性能最好的 EDABr ₂-改进后的装置实现了 14.23% 的功率转换效率，在存储 ∼4000 小时后长期保持其初始效率的 ∼93% 并提高了运行稳定性。我们的工作为选择令人满意的钝化剂和制造高效的 Sn 钙钛矿太阳能电池提供了一种有前景的方法。