Abstract

We suggest a combination of morphological control and the introduction of an additive as a strategy to completely convert thermally grown a PbI₂ layer into the perovskite structure for inverted organic–inorganic hybrid perovskite solar cells (PSCs). For 2-step PSCs based on thermal evaporation, the complete conversion of PbI₂ into the perovskite structure is a key parameter for device performance. To achieve complete conversion, we regulated the morphology of the PbI₂ layer by controlling the growth rate. Compared to rapidly grown PbI₂ layers, a PbI₂ layer grown at a slow rate contained pinholes that enhanced the diffusion of methyl ammonium iodide (MAI) from the PbI₂ surface. Despite the assistance of the pinholes, the conversion of the PbI₂ was incomplete due to the limited interaction between the MAI and PbI₂. Complete conversion of the pinhole-rich PbI₂ occurred by introducing an additive into the MAI solution. The conversion of PbI₂ was measured by grazing-incidence wide-angle X-ray scattering using synchrotron X-rays. By controlling the incidence angle of the X-rays, we quantitatively compared the amount of PbI₂ as a function of the X-ray penetration depth. Using a completely converted 50 nm-thick PbI₂ layer, we obtained a power conversion efficiency of 9.44%.

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中文翻译：

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倒钙钛矿太阳能电池中热生长的PbI 2层完全转换的策略

摘要

我们建议结合形态控制和添加剂的引入，以将热生长的PbI ₂层完全转化为钙钛矿结构，以用于有机-无机杂化钙钛矿太阳能电池（PSC）。对于基于热蒸发的两步PSC，PbI ₂完全转化为钙钛矿结构是器件性能的关键参数。为了实现完全转化，我们通过控制生长速率来调节PbI ₂层的形态。与快速生长的PbI ₂层相比，以慢速生长的PbI ₂层包含针孔，可增强甲基碘化铵（MAI）从PbI ₂的扩散表面。尽管有针孔的帮助，但由于MAI和PbI ₂之间的相互作用有限，PbI ₂的转化仍不完全。通过将添加剂引入MAI溶液中，可以完全转化出富含针孔的PbI ₂。通过使用同步加速器X射线的掠入射广角X射线散射测量PbI ₂的转化率。通过控制X射线的入射角，我们定量比较了PbI ₂的量与X射线穿透深度的关系。使用完全转换的50 nm厚的PbI ₂层，我们获得了9.44％的功率转换效率。

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