All‐perovskite tandem solar cells (TSCs) are gaining increasing attention due to their potential to surpass the efficiency limit of single‐junction solar cells. However, as the bottom low‐bandgap subcells, tin‐lead (Sn‐Pb) perovskites suffer from severe nonradiative recombination at the interfaces due to their susceptibility to oxidation and poor crystalline morphology. Here a surface modifier 4‐(trifluoromethyl)benzhydrazide (TFH) is reported to construct a reductive chemical environment on the surface of perovskite films and protect them from water and oxygen erosion. TFH anchors onto the Sn‐Pb perovskites in a preferred vertical orientation through dual‐site binding, forming interface dipoles that facilitate charge extraction. The reductive hydrazine groups of TFH can effectively inhibit the oxidation of Sn2+ and I−, thereby reducing the defect density and energy disorder of Sn─Pb perovskites. Consequently, the TFH‐treated devices achieved a champion PCE of 22.88%, maintaining over 93% of the initial efficiency after continuous one‐sun illumination for 500 h. Combined with a 1.79 eV wide‐bandgap subcell, it has demonstrated a PCE of 28.17% in all‐perovskite TSCs.

中文翻译：

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双位点锚定可实现高效的全钙钛矿叠层太阳能电池的垂直分子取向


全钙钛矿叠层太阳能电池 （TSC） 因其有可能超越单结太阳能电池的效率极限而受到越来越多的关注。然而，作为底部的低带隙子电池，锡铅 （Sn-Pb） 钙钛矿由于易氧化和晶体形态差，在界面处遭受严重的非辐射复合。据报道，表面改性剂 4-（三氟甲基）苯肼 （TFH） 可在钙钛矿薄膜表面构建还原性化学环境并保护它们免受水和氧的侵蚀。TFH 通过双位点结合以优选的垂直方向锚定到 Sn-Pb 钙钛矿上，形成促进电荷提取的界面偶极子。TFH 的还原肼基团可以有效抑制 Sn2+ 和 I− 的氧化，从而降低 Sn─Pb 钙钛矿的缺陷密度和能量无序。因此，TFH 处理的器件实现了 22.88% 的冠军 PCE，在连续单太阳照射 500 小时后保持了超过 93% 的初始效率。结合 1.79 eV 宽带隙子电池，它在全钙钛矿 TSC 中的 PCE 为 28.17%。