| Autor: |
de Wit, Jur W., Sonneveld, Lars L., Meijerink, Andries |
| Zdroj: |
Chemistry of Materials; March 2024, Vol. 36 Issue: 6 p2857-2866, 10p |
| Abstrakt: |
The optical properties of Cs2AgBiBr6double perovskite nanocrystals have attracted considerable attention as lead-free alternatives to lead halide perovskites. A promising strategy to create additional flexibility in the emission color is doping lanthanide ions into Cs2AgBiBr6. Incorporating Yb3+in the lattice has been shown to give rise to near-infrared (NIR) emission, but the energy transfer mechanism remained unclear. Here, we report on the luminescence and sensitization mechanism of Yb3+in Cs2AgBiBr6nano- and microcrystals. We observe that the incorporation of Yb3+in the host lattice does not strongly affect the broadband red emission of the Cs2AgBiBr6host but does give rise to an additional and characteristic ∼1000 nm NIR line emission from Yb3+. Temperature-dependent and time-resolved photoluminescence studies of undoped and Yb-doped Cs2AgBiBr6reveal that the energy transfer does not take place through the red emissive state of the Cs2AgBiBr6host. Instead, there is a competition between relaxation to the red-emitting state and trapping of the photoexcited charge carriers on Yb3+. Trapping on Yb3+subsequently results in a charge transfer state that relaxes to the 2F5/2excited state of Yb3+, followed by NIR narrow line f–f emission to the 2F7/2ground state. |
| Databáze: |
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