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.

Automated summary

Inactivating mobile ions/defects through chemical passivation is an effective approach to solve the instability issue in metal halide perovskite optoelectronics. This study shows that modifying the SnO2/MAPbI(3) interface with L-phenylalanine (PAA) can maintain high efficiency in high humidity conditions, and proposes a model for enhanced stability through suppressed ion migration. Additionally, the PAA dipole layer facilitates charge transfer at the interface, leading to improved power conversion efficiency in the devices.