Although much progress is made toward enhancing the efficiency of perovskite solar cells (PSCs), their operational reliability, particularly their mechanical stability, which is a crucial factor for flexible PSCs (f-PCSs), has not attracted sufficient attention. The defects in the perovskite layer, especially on the top and the buried surface of the perovskite layer, can induce perovskite fracture, highly limiting the performance of f-PSCs. Herein, a novel multifunctional organic salt, metformin hydrochloride, which can passivate cationic and anionic defects, is incorporated on both the top and buried surfaces of perovskite layer to suppress defects. As a result, a power conversion efficiency (PCE) of 24.40% for rigid PSCs and a PCE of 22.04% for f-PSCs are achieved. Simultaneously, the device can retain 90% and 80% of the initial efficiency after 1000 h of light illumination and 10 000 bending cycles, respectively, showing excellent operational stability. This study may provide a global way to design a passivation strategy and fabricate flexible perovskite solar cells with high efficiency and stability.

中文翻译：

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高效率和稳定性的柔性钙钛矿太阳能电池的顶面和埋面同时优化

尽管在提高钙钛矿太阳能电池 (PSC) 的效率方面取得了很大进展，但它们的操作可靠性，特别是机械稳定性，是柔性 PSC (f-PCS) 的关键因素，尚未引起足够的重视。钙钛矿层中的缺陷，尤其是钙钛矿层的顶部和埋藏表面，会导致钙钛矿断裂，从而极大地限制了 f-PSC 的性能。在此，一种新型的多功能有机盐，盐酸二甲双胍，可以钝化阳离子和阴离子缺陷，并结合在钙钛矿层的顶面和掩埋表面以抑制缺陷。因此，刚性 PSC 的功率转换效率 (PCE) 为 24.40%，f-PSC 的 PCE 为 22.04%。同时地，该器件在光照1000小时和弯曲10000次后分别能保持90%和80%的初始效率，表现出优异的运行稳定性。这项研究可能为设计钝化策略和制造高效稳定的柔性钙钛矿太阳能电池提供一种全球性的方法。