Impact of Mobile Ions and Performance in Perovskite Solar Cells: A Driftfusion Simulation Study

Mobile ions is important for the performance of perovskite solar cells (PSCs). To investigate the impact of mobile ions within PSCs, this study employed the Driftfusion model to explore the mobile ions behavior, specifically iodine vacancies inherent to perovskite structures. Our findings indicated that a decrease in vacancy densities correspond to a decrease in open circuit voltage (Voc) and an increase in short-circuit currents (Jsc) and efficiency. Under open-circuit condition, an ionic field is established within the device, modulating electron and hole distributions, thereby influencing band alignment and quasi-Fermi levels, which results in decreased Voc. Under short-circuit condition, the ionic field generated by mobile ions significantly impacted carrier recombination dynamics, leading to diminished Shockley-Read-Hall (SRH) recombination, thus elucidating the observed rise in Jsc. Considering the reported relationship between light soaking effect and the mobile ion density, our result unveil a potential path to quantitatively analyzing the light soaking effect of PSCs.