Bright and Photostable Alumina-Coated Perovskite Nanocrystals for Integration into Quantum Emitters

Lead halide perovskite nanocrystals, particularly CsPbBr3, are prime candidates for a variety of optical and optoelectronic applications. However, their poor stability, especially under strong irradiation, limits their practical use. In this work, we have developed a synthetic route for CsPbBr3/AlOx core/shell structures with near-unity photoluminescence quantum yield and improved photostability. The shell growth is realized through a water-free sol–gel reaction at room temperature. This approach reduces the risks of particle ripening at higher temperatures and of damaging the core nanocrystals during conventional oxide shell formation, which releases water and alcohol as side products. Moreover, the slow kinetics of the reaction allowed control of the shell thickness down to a monolayer. Finally, a nanopatch antenna structure was fabricated using the core/shell nanocrystals sandwiched between a gold surface and silver nanocubes, which led to a more than 2-fold accelerated carrier dynamics of the perovskite nanocrystals showing a fast photoluminescence decay component of 130 ps. These results contribute to the integration of CsPbBr3/AlOx core/shell nanocrystals into optoelectronic devices requiring a high emission rate, such as single-photon emitters.