Investigating the encapsulation of lead bromide perovskite with poly(3-bromothiophene) for improved aqua stability and enhanced fluorescence memory.

Formamidinium lead bromide (FAPbBr) perovskites are promising candidates for optoelectronic applications owing to their exceptional semiconducting and photoluminescent properties. However, their high sensitivity to environmental factors like moisture and polar solvents limits their long-term stability, posing a barrier to commercial applications. This study addresses this stability challenge by encapsulating FAPbBr in poly(3-bromothiophene) (PTBr), a high molecular-weight-conducting polymer, to enhance resistance to aqueous and solvent-based degradation. The PTBr encapsulation was found to significantly improve the thermal and environmental stability of FAPbBr, as evidenced by thermogravimetric analysis, which revealed a reduced and delayed mass loss and an increased residual mass (up to 28.17% in composites with 70% PTBr content). Photoluminescence studies demonstrated that the encapsulated composites exhibited a mean fluorescence lifetime of 87.4 ns, compared with 12.56% fluorescence retention in unencapsulated FAPbBr after exposure to moisture for 45 days. Moreover, encapsulated FAPbBr retained over 80% of its green light fluorescence intensity even after 1 year, whereas the unencapsulated sample degraded to less than 5%. Notably, the composites displayed fluorescence recovery upon exposure to polar solvents, further highlighting PTBr's protective role. These findings provide a practical, non-interacting encapsulation strategy that enhances both the environmental and thermal stability of FAPbBr while preserving its emission characteristics, offering potential to support the further development of perovskite-based optoelectronic devices for practical applications.