Inorganic perovskite (CsPbX 3 , X = Cl, Br and I) nanocrystals (NCs) have received great attention for their fascinating optoelectronic properties. However, their potential applications are primarily limited by the instability arising from their mobile ionic nature. Herein, we demonstrate extremely stable CsPbX 3 nanocomposites (denoted as CsPbX 3 @CA-SiO 2 ) using a facile and effective templated synthetic strategy, by the in situ anchoring of CsPbX 3 NCs onto octadecyl-/propylamine-capped silica particles (SiO 2 NPs). The two-step synthesis involves first the preparation of amino-group-capped silica NPs from a mixed 3-aminopropyltriethoxysilane (APTES) and trimethoxy(octadecyl)silane (TMODS) precursor, which were utilized to induce the nucleation and growth of CsPbX 3 nanocrystals to produce CsPbX 3 @CA-SiO 2 composites with monodispersed CsPbX 3 NCs (∼6 nm). The emission wavelength of the resulting composite can be tuned between 400 nm and 650 nm by controlling the halide composition, while maintaining a high photoluminescence quantum yield (PLQY = 76%). The as-fabricated composites exhibited remarkable photostability and water stability, both uncommon in these materials. The CsPbX 3 @CA-SiO 2 composite can also be used to create an anti-counterfeit ink and down-converting white light emitting diode (WLED). This work provides a valuable approach for the production of future optoelectronic devices, catalysts and sensors based on perovskite NCs.

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.