Enhanced stability and optical performance of CsPbBr₃@FAPbBr₃ core-shell perovskite nanocrystals

Inorganic lead halide perovskite nanocrystals (NCs), particularly CsPbBr₃, have attracted considerable attention due to their remarkable optical properties, positioning them as promising candidates for optoelectronics and bioimaging. Despite their potential, challenges such as environmental degradation and structural instability persist. Core-shell architectures and encapsulation have emerged as effective strategies to address these issues. Here, we propose a double-shelling strategy aimed at the improvement of the optical properties of perovskite NCs and their stability under harsh environmental conditions. We demonstrate the synthesis of CsPbBr₃@FAPbBr₃ core-shell NCs, combining a luminescent CsPbBr₃ core with a stabilizing FAPbBr₃ shell via a hot-injection method. This approach allows for a significant enhancement of the photoluminescence quantum yield, extension of photoluminescence lifetimes, and improvement of the photo- and thermostability of NCs. For further reinforcement of moisture resistance, we encapsulated the core-shell NCs in a SiO₂ shell to preserve their photoluminescence responses under one- and two-photon excitation in water and isopropanol. Additionally, the increased two-photon absorption cross-section of these NCs combined with water stability suggests their strong suitability for multiphoton imaging applications. This dual-shelling strategy offers a stable, high-performance perovskite-based nanomaterial, expanding the application potential of lead halide perovskite nanocrystals in light-emitting devices and bioimaging technologies.