CsPbBr₃ perovskite quantum dots grown within Fe-doped zeolite X with improved stability for sensitive NH₃ detection

All-inorganic cesium lead halide (CsPbX₃, X = Cl, Br and I) perovskite quantum dots (QDs) have received enormous research interest because of their exceptional optoelectronic properties, but their low chemical stability under ambient conditions from inevitable defects restricts their practical applications. In an effort to enhance the stability of QDs, in this study, novel functional nanocomposites were fabricated by encapsulating perovskite QDs with zeolite X doped with iron ions. Focusing on the as-obtained nanocomposites labeled with QDs@Fe/X-n, doping a reasonable amount of Fe³⁺ ions can tremendously improve the order of perovskite lattices and reduce the halide vacancies. The results of stability improvement in nanocomposites with an optimal Fe³⁺ load (QDs@Fe/X-3) are presented. After storage in air for 100 days, the emission-peak position of the composites can remain almost unchanged, and the photoluminescence (PL) intensity can reach ∼98% of the original intensity. Additionally, the PL intensity of QDs@Fe/X-3 can decrease immediately when exposing it to a NH₃ atmosphere at room temperature. The PL intensity can be linearly varied with a change in the NH₃ concentration. The original value of the PL can be rapidly recovered by separating the sample from the NH₃ environment. This work enables the QDs@Fe/X composite to be an ideal active material for ammonia sensing.