Highly efficient energy transfer in BaYF5:Yb, Tm/CsPbBr3 composites

All-inorganic CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) have attracted significant attention in recent years, owing to their high compositional tunability, large absorption coefficients, and very high photoluminescence quantum yield (PLQY) under ultraviolet (UV) or visible light excitation (Vis). However, near-infrared (NIR) triggered photon upconversion of QDs are limited by low efficiency (< 10−8) of multiphoton absorption. Yb3+ and Tm3+ codoped BaYF5 upconversion nanoparticles (UCNPs) are much more efficient (10−1–10−3) than QDs in photon upconversion, and can be excited by a low-cost continuous-wave diode laser. The limitation of QDs can be broken by integration with UCNPs, which serve as donors in the Forster resonance energy transfer (FRET) process. Therefore, the QDs can be excited under UV-Vis and NIR light. Herein we present a novel UCNPs/QDs pair formed by BaYF5: Yb, Tm and CsPbBr3 as optimal candidate to realize highly efficient green emission through NIR optical pumping.