Temperature-dependent ion migration and mobile-ion-induced degradation of perovskite solar cells under illumination

Effects of temperature-dependent ion migration on power reduction of perovskite solar cells (PSCs) under illumination were investigated at temperatures between 15 degrees C and 45 degrees C. Mobile-ion concentrations increased with temperature and the power reduction under illumination became faster at high temperatures due to an increase in the number of slow mobile ions and a decrease in the number of fast mobile ions, which was confirmed through ion migration currents. This indicates formation of deep-level defects with low mobility from the fast mobile ions (halide vacancies). Moreover, the transient power responses during maximum-power-point tracking (MPPT) became slower at high temperatures upon illumination, reflecting an increase in the number of slow mobile ions. Furthermore, the light-dark cycling test clarified that the energy yield during 8 h of illumination was reduced by similar to 10 rel% per light-dark cycle at 45 degrees C, which was accompanied by an increase in the concentration of, particularly slow, mobile ions. These results indicate that transient ion-migration analysis for evaluating the concentration of mobile ions (mobile defects) can be effective in understanding the mobile-ioninduced degradation of PSCs.

Automated summary

This study investigated the effects of temperature-dependent ion migration on the power reduction of perovskite solar cells (PSCs) under illumination. It was found that the power reduction became faster at higher temperatures due to an increase in slow mobile ions and a decrease in fast mobile ions. The concentration of mobile ions increased with temperature, resulting in the formation of deep-level defects with low mobility. Furthermore, the transient power responses during maximum-power-point tracking (MPPT) became slower at high temperatures, indicating an increase in the number of slow mobile ions.