Coevaporation, an up-scalable deposition technique that allows for conformal coverage of textured industrial silicon bottom cells, is particularly suited for application in perovskite-silicon tandem solar cells (PSTs). However, research on coevaporated perovskites with an appropriate band gap for PSTs remains limited, with lower efficiency and reproducibility than solution-processed films. Here, we present a simple approach using a thin layer of a precursor material, namely, PbI₂, PbCl₂, CsI, or CsCl, as a seed layer on the hole-transporting layer/perovskite interface. We find CsCl to be the optimal seed layer for our system. Perovskite single junction cells prepared with CsCl seed layer exhibit 19.6% power conversion efficiency with a band gap of 1.69 eV and improved long-term stability. We attribute the observed enhancements to the more precise and consistent incorporation of the organic precursor into the perovskite lattice during the film growth. This work demonstrates that engineering the substrate surface is crucial for achieving well-controlled growth of efficient and stable coevaporated wide-band gap perovskite solar cells.

中文翻译：

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用于宽带隙共蒸发钙钛矿太阳能电池的种子层：CsCl 调节带隙并减少工艺可变性


共蒸发是一种可向上扩展的沉积技术，允许对纹理工业硅底电池进行保形覆盖，特别适用于钙钛矿-硅串联太阳能电池 （PST） 中的应用。然而，对具有适当带隙的 PST 的共蒸发钙钛矿的研究仍然有限，其效率和重现性低于溶液处理的薄膜。在这里，我们提出了一种简单的方法，使用一层薄薄的前驱体材料，即 PbI₂、PbCl₂、CsI 或 CsCl，作为空穴传输层/钙钛矿界面上的种子层。我们发现 CsCl 是我们系统的最佳种子层。用 CsCl 种子层制备的钙钛矿单结电池具有 19.6% 的功率转换效率，带隙为 1.69 eV，并提高了长期稳定性。我们将观察到的增强归因于在薄膜生长过程中有机前驱体更精确、更一致地掺入钙钛矿晶格中。这项工作表明，设计衬底表面对于实现高效稳定的共蒸发宽带隙钙钛矿太阳能电池的良好受控生长至关重要。