The presence of mobile ions in metal halide perovskites has been shown to adversely affect the intrinsic stability of perovskite solar cells (PSCs). However, the actual contribution of mobile ions to the total degradation loss compared with other factors such as trap-assisted recombination remains poorly understood. Here we reveal that mobile ion-induced internal field screening is the dominant factor in the degradation of PSCs under operational conditions. The increased field screening leads to a decrease in the steady-state efficiency, often owing to a large reduction in the current density. Instead, the efficiency at high scan speeds (>1,000 V s⁻¹), where the ions are immobilized, is much less affected. We also show that the bulk and interface quality do not degrade upon ageing, yet the open-circuit voltage decreases owing to an increase in the mobile ion density. This work reveals the importance of ionic losses for intrinsic PSC degradation before chemical or extrinsic mechanical effects manifest.

金属卤化物钙钛矿中存在的移动离子已被证明会对钙钛矿太阳能电池（PSC）的固有稳定性产生不利影响。然而，与陷阱辅助重组等其他因素相比，移动离子对总降解损失的实际贡献仍然知之甚少。在这里，我们揭示了移动离子引起的内场屏蔽是操作条件下 PSC 降解的主导因素。场屏蔽的增加会导致稳态效率降低，这通常是由于电流密度的大幅降低所致。相反，离子被固定的高扫描速度（>1,000 V s ^-1 ）下的效率受到的影响要小得多。我们还表明，体积和界面质量不会因老化而降低，但由于移动离子密度的增加，开路电压会降低。这项工作揭示了在化学或外在机械效应显现之前离子损失对于内在 PSC 降解的重要性。