Owing to the combined features of sub-1.4 eV bandgap and all-inorganic composition, cesium tin–lead (Sn-Pb) triiodide perovskite is promising for approaching the Shockley-Queisser limit of solar cells while avoiding the use of volatile organic cations. But the low Sn(II) stability in this perovskite remains a hurdle for delivering its theoretically attainable device performance. Herein we present a synthesis method of this perovskite based on an acetylhydrazine-incorporated antioxidative solution system. Mechanistic investigation shows that acetylhydrazine effectively reduces the oxidation of solution-phase Sn(II) and meanwhile creates an electron-rich, protective nano-environment for solid-state Sn(II) ions. These lead to high oxidation resistance of the final film as well as effective defect inhibition. The resultant solar cells demonstrate power conversion efficiencies up to 15.04%, the highest reported so far for inorganic perovskite devices with sub-1.4 eV bandgaps. Furthermore, the T₉₀ lifetime of these devices can exceed 1000 hours upon light soaking in a nitrogen atmosphere, demonstrating the potential advantage when lower-bandgap perovskite solar cells go all-inorganic.

由于低于 1.4 eV 的带隙和全无机成分的组合特征，铯锡铅 (Sn-Pb) 三碘化钙钛矿有望在避免使用挥发性有机阳离子的同时接近太阳能电池的 Shockley-Queisser 极限。但这种钙钛矿的低 Sn(II) 稳定性仍然是实现其理论上可达到的器件性能的障碍。在此，我们提出了一种基于掺入乙酰肼的抗氧化溶液体系的这种钙钛矿的合成方法。机理研究表明，乙酰肼有效地减少了溶液相 Sn(II) 的氧化，同时为固态 Sn(II) 离子创造了一个富电子的保护性纳米环境。这些导致最终薄膜的高抗氧化性以及有效的缺陷抑制。由此产生的太阳能电池显示出高达 15.04% 的功率转换效率，这是迄今为止报告的具有低于 1.4 eV 带隙的无机钙钛矿器件的最高效率。此外，该这些器件的T ₉₀寿命在氮气氛中浸泡时可超过 1000 小时，这表明低带隙钙钛矿太阳能电池全无机化时的潜在优势。