Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
J Am Chem Soc. 2023 Mar 15;145(10):5872-5879. doi: 10.1021/jacs.2c13307. Epub 2023 Mar 5.
Passivating defects using organic halide salts, especially chlorides, is an effective method to improve power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) arising from the stronger Pb-Cl bonding than Pb-I and Pb-Br bonding. However, Cl anions with a small radius are prone to incorporation into the perovskite lattice that distorts the lead halide octahedron, degrading the photovoltaic performance. Here, we substitute atomic-Cl-containing organic molecules for widely used ionic-Cl salts, which not only retain the efficient passivation by Cl but also prevent the incorporation of Cl into the bulk lattice, benefiting from the strong covalent bonding between Cl atoms and organic frameworks. We find that only when the distance of Cl atoms in single molecules matches well with the distance of halide ions in perovskites can such a configuration maximize the defect passivation. We thereby optimize the molecular configuration to enable multiple Cl atoms in an optimal spatial position to maximize their binding with surface defects. The resulting PSCs achieve a certified PCE of 25.02%, among the highest PCEs for PSCs, and retain 90% of their initial PCE after 500 h of continuous operation.
使用有机卤化物盐（尤其是氯化物）钝化缺陷是提高钙钛矿太阳能电池（PSC）功率转换效率（PCE）的有效方法，因为 Pb-Cl 键比 Pb-I 和 Pb-Br 键更强。然而，半径较小的 Cl 阴离子容易掺入钙钛矿晶格中，从而扭曲卤化铅八面体，降低光伏性能。在这里，我们用含原子-Cl 的有机分子取代了广泛使用的离子-Cl 盐，这不仅保留了 Cl 的高效钝化作用，而且防止 Cl 掺入到体晶格中，这得益于 Cl 原子和有机框架之间的强共价键。我们发现，只有当单个分子中的 Cl 原子的距离与钙钛矿中的卤化物离子的距离很好地匹配时，这种构型才能最大限度地钝化缺陷。因此，我们优化了分子构型，使多个 Cl 原子处于最佳空间位置，从而最大限度地与表面缺陷结合。所得 PSC 的认证 PCE 达到 25.02%，是 PSC 中最高的 PCE 之一，并且在连续运行 500 小时后仍保留其初始 PCE 的 90%。
