Recently, mixed cation-halide perovskites have become particularly interesting for high-performance perovskite solar cells (PSCs) owing to their near-ideal bandgap. Nevertheless, mixed cation-halide perovskites prepared via the existing methods often subject high defect density and poor stability, especially the sequential-deposition methods in view of the difficulty of incorporating cesium cations (stabilizer). Herein, a simple and effective approach of δ-CsPbI₂Br seeds assisting sequential-deposition is developed. It is revealed that introducing δ-CsPbI₂Br seeds into PbI₂ film could not only effectively incorporate Cs⁺ into the mixed cation-halide perovskite film, but also afford δ phase crystal lattices to promote the growth of α phase perovskites during annealing. Such process can prepare high-quality perovskite film with larger grain size, lower defect density and longer photoluminescence carrier lifetime (1658 ns). In addition, the thermal and humidity stability of the perovskite film are significantly boosted. Consequently, the optimized device delivers a champion efficiency of 21.62%, with an average efficiency 1.5% higher than that of the control device. Also, the unencapsulated device exhibits remarkably operational stability, retaining ∼92% of the initial efficiency after aging for 1000 h in ambient air. This work provides insight for further preparing the high-quality perovskite film and improving the performance of PSCs.

最近，由于其接近理想的带隙，混合阳离子卤化物钙钛矿在高性能钙钛矿太阳能电池 (PSC) 中变得特别有趣。然而，通过现有方法制备的混合阳离子卤化物钙钛矿往往存在高缺陷密度和较差的稳定性，特别是顺序沉积方法，因为难以掺入铯阳离子（稳定剂）。在此，开发了一种简单有效的 δ-CsPbI ₂ Br 种子辅助顺序沉积方法。结果表明，将δ-CsPbI ₂ Br 种子引入 PbI ₂薄膜不仅可以有效地结合 Cs ⁺进入混合阳离子 - 卤化物钙钛矿薄膜，但也提供 δ 相晶格以促进 α 相钙钛矿在退火过程中的生长。该工艺可以制备具有更大晶粒尺寸、更低缺陷密度和更长光致发光载流子寿命（1658 ns）的高质量钙钛矿薄膜。此外，钙钛矿薄膜的热稳定性和湿度稳定性显着提高。因此，优化后的装置提供了21.62%的冠军效率，平均效率比控制装置高1.5%。此外，未封装的器件表现出显着的运行稳定性，在环境空气中老化 1000 小时后仍保持约 92% 的初始效率。这项工作为进一步制备高质量钙钛矿薄膜和提高 PSC 的性能提供了见解。