Stable and Efficient Upconversion Single Red Emission from CsPbI3 Perovskite Quantum Dots Triggered by Upconversion Nanoparticles.

Here, composites including highly efficient inert shell-modified NaYF4:Yb/Tm@NaYF4 upconversion nanoparticles (UCNPs) and CsPbI3 perovskite quantum dots (PQDs) have been successfully synthesized by the assistance of (3-aminopropyl)triethoxysilane (APTES) as a precursor for a SiO2 matrix. UCNPs and CsPbI3 PQDs in this composite structure show excellent stability in ambient conditions. Importantly, the efficient UC emission of CsPbI3 PQDs was realized, which means that the single red emission of inert shell-modified UCNPs can be easily obtained by depending on these composite structures. Furthermore, the single red emission wavelength can be easily regulated from 705 to 625 nm by introducing appropriate proportion of Br- ions, which is very difficult to achieve for traditional UCNPs. Moreover, benefiting from the efficient downshifting (DS) red emission of CsPbI3 PQDs, the composites possess the dual-wavelength excitation characteristics. So, the excellent dual-mode anticounterfeiting application has been demonstrated. This work will provide a new idea for the development of perovskite-based multifunctional materials.