Aging-dependent trap deactivation behavior in MAPbI3 films under varied photon energy illumination

Abstract

Organometal halide perovskites (OHPs) exhibit remarkable optoelectronic properties, such as wide visible absorption, high photoluminescence quantum yield, excellent solar-light-harvesting capabilities, and a low lasing threshold. Despite these advances, the best performance in perovskite typically occurs several hours to days post-fabrication, likely due to defect dynamics. The study of defect dynamics, particularly trap deactivation, is crucial for understanding and improving the stability and efficiency of OHPs. Furthermore, the effect of photon energy on these dynamics has not been fully explored. This study examined how aging impacts trap deactivation in MAPbI₃ films under different photon energies using photoluminescence (PL). We found that aging significantly enhanced the deactivation of two types of traps, namely T_L and T_H, especially within the first 10 days. T_L and T_H ware traps in MAPbI₃ that can be deactivated by low and high photon energy thresholds, respectively. PL enhanced more than doubled during this period, attributed to a small amount of oxygen penetration in vacuum conditions aiding trap deactivation. PL increased linearly with increasing aging, and trap deactivation time increased exponentially with age for both T_L and T_H deactivation. After 27 days, blue photon illumination resulted in reversible degradation and reactivation of the previously deactivated T_L and T_H traps. However, red photon illumination remained capable of deactivating the T_L traps. This research highlights the interplay between light-induced trap dynamics and aging, which is crucial for optimizing MAPbI₃ perovskite durability and performance in optoelectronic applications.