Shallow defects are mostly benign in covalent semiconductors, such as silicon, given that they do not constitute non-radiative recombination sites. In contrast, the existence of shallow defects in ionic perovskite crystals might have significant repercussions on the long-term stability of perovskite solar cells (PSCs) because of the metastability of the ubiquitous formamidinium lead triiodide (FAPbI₃) perovskite and the migration of charged point defects. Here, we show that shallow iodine interstitial defects ($I_i$) can be generated unintentionally during commonly used post-fabrication treatments, which can lower the cubic-to-hexagonal transformation barrier of FAPbI₃-based perovskites to accelerate its phase degradation. We demonstrate that concurrently avoiding the generation of $I_i$ and the more effective passivation of iodine vacancies ($V_I$) can improve the thermodynamic stability of the films and operational stability of the PSCs. Our most stable PSC retained 92.1 % of its initial performance after nearly 1,000 h of continuous illumination operational stability testing.

浅缺陷在诸如硅之类的共价半导体中主要是良性的，因为它们不构成非辐射复合位点。相比之下，离子钙钛矿晶体中浅缺陷的存在可能对钙钛矿太阳能电池（PSC）的长期稳定性产生重大影响，这是因为普遍存在的甲碘化三碘化铅（FAPbI ₃）钙钛矿的亚稳定性和带电点的迁移缺陷。在这里，我们显示出浅碘间隙缺陷（${\mathrm{一世}}_{\mathrm{一世}}$）可以在常用的后加工处理过程中无意中生成，这可以降低基于FAPbI ₃的钙钛矿的立方到六方转变势垒，从而加速其相降解。我们证明了同时避免产生${\mathrm{一世}}_{\mathrm{一世}}$ 以及更有效地钝化碘空位（$V_{\mathrm{一世}}$）可以改善薄膜的热力学稳定性和PSC的操作稳定性。经过近1,000小时的连续照明操作稳定性测试，我们最稳定的PSC保留了其最初性能的92.1％。