As perovskite solar cells have yielded impressive efficiency at a low cost, the focus has shifted to increase their service life as they are plagued by rapid degradation. Refreshingly, CsPbBr₃ solar cells built on a conductive ZnO nanowire electron transport layer with a graphite counter electrode not only avoided degradation but also showed some of the reverse trends under specific conditions, showing significant maturation over time. In this work, this phenomenon is first confirmed to be reproducible from a large sample size with on average a 40 ± 10% increase in efficiency after 2 weeks of storage. To explore the mechanisms of this positive maturing effect, samples were stored under different controlled conditions and tested regularly by using scanning electron microscopy, powder X-ray diffraction, current–voltage (IV) curves, and impedance spectroscopy. The samples stored in a methanol atmosphere presented a dramatic positive effect, giving a 4-fold increase in efficiency after 2 days of storage. However, in the saturated H₂O environment, the device performance rapidly degraded. By observing the solar cell performance affected by various storage conditions, including various solvent vapors, light illumination, and an inert gas (N₂), we suggest three possible complementary factors. First, solvents shifted the equilibrium of crystal phase ratio of CsPbBr₃ to CsPb₂Br₅. Second, the CsPbBr₃ grain size was reduced with improved electrical contact with the conductive ZnO nanowires. Finally, ion migration and accumulation lead to the formation of local p–n junctions at crystal grain boundaries with improved charge separation. This was evidenced by the increased kinetic relaxation times on ionic time scales. Rather than degrading, under appropriate conditions, these cells were able to increase in value/efficiency over storage time. By elucidating the underlying mechanisms for the CsPbBr₃ solar cell stability, the work offers guidelines for improving perovskite solar cell long-term efficiency.

中文翻译：

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在不同储存条件下对所有无机 CsPbBr3 钙钛矿太阳能电池的显着成熟效应

由于钙钛矿太阳能电池以低成本获得了令人印象深刻的效率，但由于受到快速降解的困扰，重点已转移到延长其使用寿命上。令人耳目一新的是，CsPbBr ₃建立在具有石墨对电极的导电 ZnO 纳米线电子传输层上的太阳能电池不仅避免了退化，而且在特定条件下也表现出一些相反的趋势，随着时间的推移表现出显着的成熟。在这项工作中，这种现象首先被证实可以从大样本量中重现，储存 2 周后效率平均提高 40 ± 10%。为了探索这种正成熟效应的机制，将样品储存在不同的受控条件下，并通过使用扫描电子显微镜、粉末 X 射线衍射、电流 - 电压（IV) 曲线和阻抗谱。储存在甲醇气氛中的样品表现出显着的积极效果，储存 2 天后效率提高了 4 倍。然而，在饱和的 H ₂ O 环境中，器件性能迅速下降。通过观察受各种储存条件影响的太阳能电池性能，包括各种溶剂蒸气、光照和惰性气体 (N ₂ )，我们提出了三个可能的补充因素。首先，溶剂使CsPbBr ₃与CsPb ₂ Br ₅的晶相比的平衡移动。二、CsPbBr ₃随着与导电 ZnO 纳米线的电接触的改善，晶粒尺寸减小。最后，离子迁移和积累导致在晶界处形成局部 p-n 结，并改善电荷分离。离子时间尺度上增加的动力学弛豫时间证明了这一点。在适当的条件下，这些电池不会降解，而是能够随着存储时间的推移而增加价值/效率。通过阐明 CsPbBr ₃太阳能电池稳定性的潜在机制，该工作为提高钙钛矿太阳能电池的长期效率提供了指导。