Advancing inverted (p–i–n) perovskite solar cells (PSCs) is key to further enhance the power conversion efficiency (PCE) and stability of flexible and perovskite-based tandem photovoltaics. Yet, the presence of defects at grain boundaries and in particular interfacial recombination at the perovskite/electron transporting layer interface induce severe non-radiative recombination losses, limiting the open-circuit voltage (V_OC) and fill factor (FF) of PSCs in this architecture. In this work, we introduce a dual passivation strategy using the long chain alkylammonium salt phenethylammonium chloride (PEACl) both as an additive and for surface treatment to simultaneously passivate the grain boundaries and the perovskite/C₆₀ interface. Using [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) as a hole transporting layer and a methylammonium (MA)-free Cs_0.18FA_0.82PbI₃ perovskite absorber with a bandgap of ∼1.57 eV, prolonged charge carrier lifetime and an on average 63 meV enhanced internal quasi-Fermi level splitting are achieved upon dual passivation compared to reference p–i–n PSCs. Thereby, we achieve one of the highest PCEs for p–i–n PSCs of 22.7% (stabilized at 22.3%) by advancing simultaneously the V_OC and FF up to 1.162 V and 83.2%, respectively. Using a variety of experimental techniques, we attribute the positive effects to the formation of a heterogeneous 2D Ruddlesden–Popper (PEA)₂(Cs_1−xFA_x)_n−1Pb_n(I_1−yCl_y)_3n+1 phase at the grain boundaries and surface of the perovskite films. At the same time, the activation energy for ion migration is significantly increased, resulting in enhanced stability of the PSCs under light, humidity, and thermal stress. The presented dual passivation strategy highlights the importance of defect management both in the grain boundaries and the surface of the perovskite absorber layer using a proper passivation material to achieve both highly efficient and stable inverted p–i–n PSCs.

中文翻译：

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一石两鸟：双晶界和界面钝化使效率> 22％的倒置无甲基铵钙钛矿太阳能电池

推进倒置（p-i-n）钙钛矿太阳能电池（PSC）是进一步提高柔性和基于钙钛矿的串联光伏的功率转换效率（PCE）和稳定性的关键。然而，晶界处缺陷的存在，特别是钙钛矿/电子传输层界面处的界面复合会导致严重的非辐射复合损失，从而限制了PSC的开路电压 ( V _OC ) 和填充因子 (FF)建筑学。在这项工作中，我们引入了一种双重钝化策略，使用长链烷基铵盐苯乙基氯化铵 (PEACl) 作为添加剂和表面处理，同时钝化晶界和钙钛矿/C ₆₀界面。使用 [2-(9 H-咔唑-9-基）乙基]膦酸（2PACz）作为空穴传输层和不含甲基铵（MA）的Cs _0.18 FA _0.82 PbI ₃钙钛矿吸收剂，带隙为~1.57 eV，延长了电荷载流子寿命和与参考 p-i-n PSC 相比，双钝化实现了平均 63 meV 增强的内部准费米能级分裂。由此，我们获得最高的PCE中的一个用于P-I-N通过同时推进的22.7％（22.3％稳定的）的PSC V _OC和FF分别高达1.162 V和83.2％。使用各种实验技术，我们将积极影响归因于异质 2D Ruddlesden-Popper (PEA) ₂ (Cs _{1− x} FA) 的形成_x ) _{n -1} Pb _n (I _{1− y} Cl _y ) _{3 n +1}相在钙钛矿薄膜的晶界和表面。同时，离子迁移的活化能显着增加，从而增强了 PSC 在光、湿度和热应力下的稳定性。所提出的双钝化策略强调了使用适当的钝化材料在晶界和钙钛矿吸收层表面进行缺陷管理的重要性，以实现高效和稳定的倒置 p-i-n PSC。