Ion migration and subsequent accumulation at interfaces, driven by the built-in potential (V_bi), are intrinsic properties of halide perovskite solar cells (PVSCs), which mostly decrease the device performance. To address this issue, we constructed favorable ion accumulation in perovskite solar cells via illumination to improve the performance of the quasi-2D PVSCs. This design dramatically improves the photo-carrier collection and enables significant device performance improvement from 14.6% to 19.05%, one of the best results for quasi-2D PVSCs. We argue that the light-triggered favorable ion accumulation originates from (1) the photo-induced quasi-Fermi level splitting that compensates the V_bi, so as to avoid the ion accumulation that decreases V_bi, and (2) the light-intensity-distribution-induced uneven ion potential further drives the segregation of mobile ions towards favorable ion accumulation, decreasing any I⁻ gradient between the anode and cathode. Our work provides insight into the fundamental understanding of ion accumulation in perovskite-based optoelectronic devices and paves the way to more stable, high-performance PVSCs.

中文翻译：

---

高性能准二维钙钛矿太阳能电池的光诱导有益离子积累

由内建电位 ( V _bi )驱动的离子迁移和随后在界面处的积累是卤化物钙钛矿太阳能电池 (PVSC) 的固有特性，这主要会降低器件性能。为了解决这个问题，我们通过光照在钙钛矿太阳能电池中构建了有利的离子积累，以提高准二维 PVSC 的性能。这种设计极大地改善了光载流子的收集，并使器件性能从 14.6% 显着提高到 19.05%，这是准 2D PVSC 的最佳结果之一。我们认为光触发的有利离子积累源于 (1) 补偿V _{bi的光诱导准费米能级分裂}，以避免降低V _bi的离子积累，以及 (2) 光强分布引起的不均匀离子电位进一步推动移动离子向有利的离子积累方向分离，从而降低阳极和阴极之间的任何 I ^-梯度. 我们的工作提供了对钙钛矿基光电器件中离子积累的基本理解的深入了解，并为更稳定、高性能的 PVSC 铺平了道路。