Stable Luminous Nanocomposites of Confined Mn²⁺-Doped Lead Halide Perovskite Nanocrystals in Mesoporous Silica Nanospheres as Orange Fluorophores

Creating highly stable inorganic perovskite nanocrystals (CsPbX₃, where X = Cl, Br, and I) with excellent optical performance is challenging because their optical properties depend on their ionic structure and its inherent defects. Here, we present a facile and effective synthesis using a nanoconfinement strategy to grow Mn²⁺-doped CsPbCl₃ nanocrystals embedded in dendritic mesoporous silica nanospheres (MSNs). The resulting nanocomposite is abbreviated as Cs(Pb_x/Mn_1-x)Cl₃@MSNs and can serve as the orange emitter for white light-emitting diodes (WLEDs). The MSN matrix was prepared via a templated sol-gel technique as monodispersed center-radial dendritic porous particles, with a diamater of ∼105 nm and an inner pore size of ∼13 nm. The MSN was then utilized as the matrix to initiate the growth of Mn-doped perovskite nanocrystals (NCs). The NCs in the resulting composite have an average diameter of 8 nm and a photoluminescence quantum yield of >30%. In addition, the optical properties of the Cs(Pb_x/Mn_1-x)Cl₃@MSNs can be tuned by varying the Mn²⁺ doping level. The resulting composites presented a significantly improved resistance to ultraviolet (UV) light, temperature, and moisture compared to that of bare Cs(Pb_0.72/Mn_0.28)Cl₃. Finally, we fabricated down-converting WLEDs by using Cs(Pb_x/Mn_1-x)Cl₃@MSNs as the orange-emitting phosphor deposited onto UV-emitting chips, demonstrating their promising applications in solid-state lighting. This work provides a valuable approach to fabricating stable orange luminophores as replacements for traditional emitters in light-emitting diode devices.