Stability of PEA ₂ PbBr ₄ Thin‐Film Photodetectors under Thermal and Moisture Stress

ABSTRACT Low‐dimensional perovskite photodetectors attract significant attention due to their tunable optoelectronic properties, quantum confinement effects and solution processability. Among them, phenethylammonium lead bromide (PEA 2 PbBr 4 ) is more stable than its 3D counterparts. However, degradation under environmental stress remains an obstacle to practical applications, particularly with prolonged exposure to temperature and humidity. This study systematically evaluates the impact of these stressors on the morphology, crystallinity, and optoelectronic performance of PEA 2 PbBr 4 photodetectors. The impact of the halogen‐bonding additive 1,4‐TFIB (1,4‐diiodotetrafluorobenzene) on the stability of the devices is also considered. Here, the devices were subjected to an increase in temperature (20°C–120°C) and humidity (40%RH–98%RH) in five steps, with each condition maintained for two days. Morphological and structural analyses are performed, as well as optoelectronic analyses under UV light and X‐ray irradiation. The results show that, while pristine films undergo significant physical degradation and material loss at elevated temperature and humidity, the incorporation of 1,4‐TFIB significantly enhances material endurance. Although the additive reduces the photocurrent signal of the device under UV and X‐ray irradiation, it mitigates physical loss of the material and maintains structural integrity in harsh conditions, thereby enhancing device longevity in optoelectronic sensing applications.