The majority of high-efficiency Sn–Pb perovskite solar cells (PSCs) have used methylammonium (MA) cation and PEDOT:PSS hole transport layer (HTL) which limits the device performance, especially in terms of stability. In this work, we propose a highly efficient and remarkably stable MA-free Sn–Pb PSC based on an inorganic HTL (NiO_x), utilizing GeO_x passivation derived from GeI₂ additive. Using depth profiling analysis, we demonstrate for the first time that GeI₂ additive–GeO_x has a very detrimental effect on the PEDOT:PSS/Sn–Pb perovskite system, while it is efficacious on the NiO_x/Sn–Pb perovskite system. The GeI₂ additive–GeO_x passivation effectively mitigates defect states and non-radiative recombination in the MA-free Sn–Pb perovskite by inhibiting Ni³⁺ formation and efficiently suppressing Sn²⁺ oxidation in the NiO_x/Sn–Pb perovskite system. Additionally, the GeO_x on the NiO_x surface exhibits excellent band alignment, resulting in outstanding charge extraction. Consequently, our MA-free Sn–Pb PSC shows an unprecedented efficiency of 23.34% (certified 22.9%) which is the highest among MA-free Sn–Pb PSCs employing an inorganic HTL instead of PEDOT:PSS, and exhibits exceptional long-term stability, maintaining over 95% of the initial power conversion efficiency for 4320 hours with encapsulation (88% without encapsulation). Our findings suggest promising prospects for efficient and stable MA-free Sn–Pb photovoltaic devices, potentially replacing PEDOT:PSS.

中文翻译：

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前所未有的无机 HTL 基无 MA 锡铅钙钛矿光伏电池，效率超过 23%


大多数高效锡铅钙钛矿太阳能电池（PSC）都使用甲基铵（MA）阳离子和PEDOT:PSS空穴传输层（HTL），这限制了器件性能，特别是在稳定性方面。在这项工作中，我们提出了一种基于无机 HTL (NiO _x ) 的高效且非常稳定的无 MA Sn-Pb PSC，利用源自 GeI ₂添加剂的 GeO _x钝化。通过深度分析，我们首次证明GeI ₂添加剂–GeO _x对PEDOT:PSS/Sn–Pb钙钛矿体系具有非常不利的影响，而它对NiO _x /Sn–Pb钙钛矿体系有效。 GeI ₂添加剂-GeO _x钝化通过抑制 NiO _x /Sn-Pb 钙钛矿体系中 Ni ^{3+ 的}形成并有效抑制 Sn ²⁺氧化，有效减轻无 MA Sn-Pb 钙钛矿中的缺陷态和非辐射复合。此外，NiO _x表面上的GeO _x表现出出色的能带排列，从而实现出色的电荷提取。因此，我们的不含 MA 的 Sn-Pb PSC 显示出前所未有的 23.34% 效率（经过认证 22.9%），这是采用无机 HTL 代替 PEDOT:PSS 的无 MA Sn-Pb PSC 中最高的，并且表现出卓越的长期稳定性，在封装的情况下可在 4320 小时内保持超过 95% 的初始功率转换效率（88 % 无封装）。我们的研究结果表明高效、稳定的无 MA Sn-Pb 光伏器件前景广阔，有可能取代 PEDOT:PSS。