Studying the Role of Ion Migration on Perovskite Light-Emitting Diodes by Steady-State approach

Despite the rapid development of perovskite-based light-emitting diodes (PeLEDs) within the last decade, the role of ion migration on the devices' operation has not been completely understood. It is considered the most complicated and mysterious process, affecting PeLED's operation. On one hand, it is widely accepted that the ion migration, as an intrinsic phenomenon, is one of the main origins for PeLEDs' low stability and on the other hand, the defect passivation caused by mobile ions gives rise to enhanced charge injection from the electron and hole transporting layers, leading to the more efficient light-emitting diodes. Therefore, it is critical to have a comprehensive insight into the underlying principles of ion migration and its contributing factors. In this paper, the ion migration phenomenon and its influence on the operation of a PeLED are surveyed using the Finite Element Method (FEM) simulation. The accumulation of anions and cations at the hole and electron transporting layer's interfaces with the perovskite facilitates hole and electron injection, respectively, which results in more carrier density favoring the radiative recombination. Thereupon, ion migration is a phenomenon that is closely related to the device's operation and stability, by controlling which a more stable PeLED is attainable. Our results provide a better understanding of the physics behind the ion migration which is the first step for designing more efficient devices.