The degradation of perovskite solar cells in the presence of trace water and oxygen poses a challenge for their commercial impact given the appreciable permeability of cost-effective encapsulants. Point defects were recently shown to be a major source of decomposition due to their high affinity for water and oxygen molecules. Here, we report that, in single-cation/halide perovskites, local lattice strain facilitates the formation of vacancies and that cation/halide mixing suppresses their formation via strain relaxation. We then show that judiciously selected dopants can maximize the formation energy of defects responsible for degradation. Cd-containing cells show an order of magnitude enhanced unencapsulated stability compared to state-of-art mixed perovskite solar cells, for both shelf storage and maximum power point operation in ambient air at a relative humidity of 50%. We conclude by testing the generalizability of the defect engineering concept, demonstrating both vacancy-formation suppressors (such as Zn) and promoters (such as Hg).

鉴于具有成本效益的密封剂具有明显的渗透性，在痕量水和氧气的存在下钙钛矿太阳能电池的降解对其商业影响提出了挑战。由于其对水和氧分子的高亲和力，最近发现点缺陷是分解的主要来源。在这里，我们报道，在单阳离子/卤化物钙钛矿中，局部晶格应变促进空位的形成，而阳离子/卤化物混合则通过应变松弛抑制了它们的形成。然后我们表明，明智地选择掺杂剂可以使负责降解的缺陷的形成能最大化。与现有技术的混合钙钛矿太阳能电池相比，含Cd电池的未封装稳定性提高了一个数量级，可在相对湿度为50％的环境空气中同时进行搁板存储和最大功率点操作。我们通过测试缺陷工程概念的普遍性来得出结论，展示了空位形成抑制剂（如Zn）和促进剂（如Hg）。