| Autor: |
Fischer S; Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.; Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States., Bronstein ND; Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.; Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States., Swabeck JK; Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.; Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States., Chan EM; Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States., Alivisatos AP; Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.; Department of Chemistry, University of California-Berkeley , Berkeley, California 94720, United States.; Department of Materials Science and Engineering, University of California-Berkeley , Berkeley, California 94720, United States.; Kavli Energy NanoScience Institute , Berkeley, California 94720, United States. |
| Abstrakt: |
Lanthanide-doped nanocrystals are of particular interest for the research community not only due to their ability to shape light by downshifting, quantum cutting, and upconversion but also because novel optical properties can be found by the precise engineering of core-shell nanocrystals. Because of the large surface area-to-volume ratio of nanocrystals, the luminescence is typically suppressed by surface quenching. Here, we demonstrate a mechanism that exploits surface quenching processes to improve the luminescence of our core-shell lanthanide-doped nanocrystals. By carefully tuning the shell thickness of inert β-NaLuF 4 around β-NaYF 4 nanocrystals doped with Yb 3+ and Er 3+ , we unravel the relationship between quantum yield and shell thickness, and quantify surface quenching rates for the relevant Er 3+ and Yb 3+ energy levels. This enhanced understanding of the system's dynamics allowed us to design nanocrystals with a surface quenching-assisted mechanism for bright NIR to NIR downshifting with a distinctive efficiency peak for an optimized shell thickness. |
