Impact of Ion Migration on the Time-Transient Performance of Perovskite LEDs
Paria Forozi-Sowmeeh a, Mohamad Zohor-Fazeli a, Elnaz Yazdani a
a Department of Physics, Faculty of Basic Sciences, Tarbiat Modares University, Tehran, Iran
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
, Paria Forozi-Sowmeeh, presentation 286
Publication date: 20th April 2022

In the last few years, external quantum efficiencies of over 20% have been reported for Perovskite LEDs. However, due to the ionic nature of the Perovskite materials, the characterization of the Perovskite LEDs is often sensitive to the measurement procedures [1]. The J-V hysteresis in Perovskite solar cells has been extensively investigated and attributed to ion migration. Herein, to realize the hysteric behavior of PeLEDs, time transient responses of the cations and anions under applied bias using the Drift-Diffusion Model (DDM) have been studied. Due to the fast dynamics of the Perovskite LEDs operation, the main simulation results have been conducted for physics occurring on time scales of a microsecond to seconds. The results show that anions and cations migrate in different time scales (microseconds to a few seconds) because of their mobility difference, and accumulate at perovskite interfaces with HTL and ETL, which bring about time-transient electric field redistribution and dynamic charge injection [2, 3] hence, slow response of current. The simulation results demonstrate a transient current response at short times and reaching the steady-state current after a few seconds[4]. To differentiate the impact of different mobile spices on electron and hole injection, we have divided the transient current response of PeLED into different phases: the initial RC response and inrush current of PeLED, current drop simultaneous to anions migration, and current rise to steady-state value after cations migration. The cation migration time scale controls the PeLED's turn-on time. Our results reveal a comprehensive understanding of the ion migration-related transient phenomena, which is the first step to achieving hysteresis-free, efficient, and more stable PeLEDs.

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