Understanding the Effect of Lead Iodide Excess on the Performance of Methylammonium Lead Iodide Perovskite Solar Cells,ACS Energy Letters

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Understanding the Effect of Lead Iodide Excess on the Performance of Methylammonium Lead Iodide Perovskite Solar Cells
ACS Energy Letters ( IF 19.3 ) Pub Date : 2022-05-10 , DOI: 10.1021/acsenergylett.2c00850
Zeeshan Ahmad ₁ , Rebecca A. Scheidt ₂ , Matthew P. Hautzinger ₂ , Kai Zhu ₂ , Matthew C. Beard ₂ , Giulia Galli _{1,

3,

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Affiliation

The presence of unreacted lead iodide in organic–inorganic lead halide perovskite solar cells is widely correlated with an increase in power conversion efficiency. We investigate the mechanism for this increase by identifying the role of surfaces and interfaces present between methylammonium lead iodide perovskite films and excess lead iodide. We show how type I and II band alignments arising under different conditions result in either passivation of surface defects or hole injection. Through first-principles simulations of solid–solid interfaces, we find that lead iodide captures holes from methylammonium lead iodide and modulates the formation of defects in the perovskite, affecting recombination. Using surface-sensitive optical spectroscopy techniques, such as transient reflectance and time-resolved photoluminescence, we show how excess lead iodide affects the diffusion and surface recombination velocity of charge carriers in methylammonium lead iodide films. Our coupled experimental and theoretical results elucidate the role of excess lead iodide in perovskite solar cells.

中文翻译：

了解碘化铅过量对甲基铵碘化铅钙钛矿太阳能电池性能的影响

有机-无机卤化铅钙钛矿太阳能电池中未反应的碘化铅的存在与功率转换效率的提高广泛相关。我们通过确定甲基铵碘化铅钙钛矿薄膜和过量碘化铅之间存在的表面和界面的作用来研究这种增加的机制。我们展示了在不同条件下产生的 I 型和 II 型能带排列如何导致表面缺陷的钝化或空穴注入。通过固-固界面的第一性原理模拟，我们发现碘化铅从甲基铵碘化铅中捕获空穴并调节钙钛矿中缺陷的形成，从而影响复合。使用表面敏感的光谱技术，例如瞬态反射和时间分辨光致发光，我们展示了过量的碘化铅如何影响甲基铵碘化铅薄膜中电荷载流子的扩散和表面复合速度。我们的耦合实验和理论结果阐明了过量碘化铅在钙钛矿太阳能电池中的作用。

更新日期：2022-05-10

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