Schroter, Alexandra and Maerkl, Susanne and Weitzel, Naomi and Hirsch, Thomas (2022) Upconversion Nanocrystals with High Lanthanide Content: Luminescence Loss by Energy Migration versus Luminescence Enhancement by Increased NIR Absorption. ADVANCED FUNCTIONAL MATERIALS, 32 (26): 2113065. ISSN 1616-301X, 1616-3028
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Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted a lot of interest due to their benefits in biological applications: They are not suffering from intermittence and provide nearly background-free luminescence. The progress in synthesis nowadays enables access to complex core-shell particles of controlled size and composition. Nevertheless, the frequently used doping ratio dates back to where mostly core-only particles of relatively large size have been studied. Especially at low power excitation as needed in biology, a decrease in particle size leads to a drastic decrease in the upconversion efficiency. An enhancement strategy based on an increased absorption rate of near-infrared light provided by an increase of the sensitizer content, together with the simultaneous blocking of the energy migration pathways to the particle surface, is presented. NaYbF4(20%Er) particles of 8.5 nm diameter equipped with an about 2 nm thick NaYF4 shell show significantly enhanced upconversion luminescence in the red (660 nm) compared to the most commonly used particles with only 20% Yb3+ and 2% Er3+. The impact of size, composition, and core-shell architecture on photophysical properties are studied. The findings demonstrate that an increase in doping rates enables the design of small, bright UCNPs useful for biological applications.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CONFINING EXCITATION-ENERGY; QUANTUM YIELDS; NANOPARTICLES; CORE; DYNAMICS; SURFACE; EMISSIONS; DESIGN; lanthanides; luminescence; nanoparticles; near-infrared; upconversion |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik > Chemo- und Biosensorik (Prof. Antje J. Bäumner, formerly Prof. Wolfbeis) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 27 Nov 2023 06:07 |
| Last Modified: | 27 Nov 2023 06:07 |
| URI: | https://pred.uni-regensburg.de/id/eprint/56784 |
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