The instability issue of Pb-free Sn-based perovskite is one of the biggest challenges for its application in optoelectronic devices. Herein, a structural regulation strategy is demonstrated to regulate the geometric symmetry of formamidiniumtin iodide (FASnI₃) perovskite. Experimental and theoretical works show that the introduction of cesium cation (Cs⁺) could improve the geometric symmetry, suppress the oxidation of Sn²⁺, and enhance the thermodynamical structural stability of FASnI₃. As a result, the inverted planar Cs-doped FASnI₃-based perovskite solar cell (PSC) is shown to maintain 90% of its initial power-conversion efficiency (PCE) after 2000 h stored in N₂, which is the best durability to date for 3D Sn-based PSCs. Most importantly, the air, thermal, and illumination stabilities of the PSCs are all improved after Cs doping. The PCE of the Cs-doped PSC shows a 63% increase compared to that of the control device (from 3.74% to 6.08%) due to the improved quality of the Cs-doped FASnI₃ film.

中文翻译：

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通过结构调节实现高效无铅甲Form碘化钛钙钛矿型太阳能电池的鲁棒稳定性

无铅锡基钙钛矿的不稳定性问题是其在光电器件中应用的最大挑战之一。在本文中，证明了一种结构调节策略来调节碘化甲酰胺锡（FASnI ₃）钙钛矿的几何对称性。实验和理论工作表明，引入铯阳离子（Cs ⁺）可以改善几何对称性，抑制Sn ²⁺的氧化，并增强FASnI ₃的热力学结构稳定性。结果表明，在N _2中储存2000 h后，倒置的平面Cs掺杂的基于FASnI ₃的钙钛矿型太阳能电池（PSC）保持其初始功率转换效率（PCE）的90％。，这是迄今为止基于3D Sn的PSC的最佳耐用性。最重要的是，掺杂Cs后，PSC的空气，热和光照稳定性都得到了改善。由于掺Cs的FASnI ₃薄膜的质量提高，掺Cs的PSC的PCE较控制装置的PCE增长了63％（从3.74％增至6.08％）。