Manipulating Ion Migration and Interfacial Carrier Dynamics via Amino Acid Treatment in Planar Perovskite Solar Cells

Instability caused by the migrating ions is one of the major obstacles toward the large-scale application of metal halide perovskite optoelectronics. Inactivating mobile ions/defects via chemical passivation, e.g., amino acid treatment, is a widely accepted approach to solve that problem. To investigate the detailed interplay, L-phenylalanine (PAA), a typical amino acid, is used to modify the SnO2/MAPbI(3) interface. The champion device with PAA treatment maintains 80% of its initial power conversion efficiency (PCE) when stored after 528 h in an ambient condition with the relative humidity exceeding 70%. By employing a wide-field photoluminescence imaging microscope to visualize the ion movement and calculate ionic mobility quantitatively, we propose a model for enhanced stability in perspective of suppressed ion migration. Besides, we reveal that the PAA dipole layer facilitates charge transfer at the interface, enhancing the PCE of devices. Our work may provide an in-depth understanding toward high-efficiency and stable perovskite optoelectronic devices.

迁移离子导致的不稳定性是金属卤化物钙钛矿光电器件大规模应用的主要障碍之一。通过化学钝化（例如氨基酸处理）使可移动离子/缺陷失活是解决该问题的一种广泛接受的方法。为了研究详细的相互作用，一种典型的氨基酸L - 苯丙氨酸（PAA）被用于修饰SnO₂/MAPbI₃界面。经过PAA处理的最优器件在相对湿度超过70%的环境条件下储存528小时后，仍能保持其初始功率转换效率（PCE）的80%。通过使用宽场光致发光成像显微镜来观察离子运动并定量计算离子迁移率，我们从抑制离子迁移的角度提出了一种提高稳定性的模型。此外，我们揭示了PAA偶极层促进了界面处的电荷转移，提高了器件的PCE。我们的工作可能为高效且稳定的钙钛矿光电器件提供深入的理解。