Three-order fluorescence enhancement of perovskite nanocrystals using plasmonic Ag@SiO2 nanocomposites

Abstract

All-inorganic perovskite nanocrystals have drawn great attention for various photoelectric devices. However, pristine blue-emitting perovskite nanocrystals suffer from low fluorescence intensity, limiting their applications. Localized optical field manipulation using metal nanostructures is a promising strategy to boost the luminescence performance of perovskite nanocrystals. Herein, we synthesized novel Ag@SiO₂@CsPbX₃ (X = Cl, Br, I, and their mixtures) composites for the first time, obtaining a remarkable luminescence enhancement for all the perovskite nanocrystals. Particularly, an extreme improvement of the blue emitting fluorescence of CsPbCl_1.5Br_1.5 by more than 1,000 times is realized in Ag@SiO₂@CsPbCl_1.5Br_1.5 composites. The experimental and theoretical results (finite-difference time-domain simulation) reveal that such high enhancement is ascribed to a well match between the excitation/emission of CsPbCl_1.5Br_1.5 nanocrystals and localized surface plasmon resonance absorption of Ag nanospheres, resulting in the absorption and emission enhancement of perovskite nanocrystals. Our work offers a new way to improve the fluorescence intensity of perovskite nanocrystals and opportunity for their future application in optoelectronic devices.