Stable luminous nanocomposites of CsPbX ₃ perovskite nanocrystals anchored on silica for multicolor anti-counterfeit ink and white-LEDs

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.