Upconversion luminescence with tunable lifetime in NaYF4:Yb,Er nanocrystals: role of nanocrystal size.
- Publication Type:
- Journal Article
- Nanoscale, 2013, 5 (3), pp. 944 - 952
- Issue Date:
|dc.identifier.citation||Nanoscale, 2013, 5 (3), pp. 944 - 952||en_US|
|dc.description.abstract||Despite recent achievements to reduce surface quenching in NaYF(4):Yb,Er nanocrystals, a complete understanding of how the nanocrystal size affects the brightness of upconversion luminescence is still incomplete. Here we investigated upconversion luminescence of Yb,Er-doped nanocrystals in a broad range of sizes from 6 nm to 45 nm (cubic or hexagonal phases), displaying an increasing red-to-green luminescence intensity ratio and reduced luminescence lifetimes with decreasing size. By analyzing the upconversion process with a set of rate equations, we found that their asymptotic analytic solutions explain lower decay rates of red compared to green upconversion luminescence. Furthermore, we quantified the effect of the surface on luminescence lifetime in a model where nanocrystal emitters are divided between the near-surface and inside regions of each nanocrystal. We clarify the influence of the four nonradiative recombination mechanisms (intrinsic phonon modes, vibration energy of surface ligands, solvent-mediated quenching, and surface defects) on the decay rates for different-size nanocrystals, and find that the defect density dominates decay rates for small (below 15 nm) nanocrystals. Our results indicate that a defect-reduction strategy is a key step in producing small upconversion nanocrystals with increased brightness for a variety of bioimaging and biosensing applications.||en_US|
|dc.subject.classification||Nanoscience & Nanotechnology||en_US|
|dc.title||Upconversion luminescence with tunable lifetime in NaYF4:Yb,Er nanocrystals: role of nanocrystal size.||en_US|
|utslib.for||0205 Optical Physics||en_US|
|utslib.for||0912 Materials Engineering||en_US|
|utslib.for||02 Physical Sciences||en_US|
|utslib.for||03 Chemical Sciences||en_US|
|pubs.organisational-group||/University of Technology Sydney|
|pubs.organisational-group||/University of Technology Sydney/Faculty of Science|
|pubs.organisational-group||/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences|
|pubs.organisational-group||/University of Technology Sydney/Strength - IBMD - Initiative for Biomedical Devices|
OPUS (Open Publications of UTS Scholars) is the UTS institutional repository. It showcases the research of UTS staff and postgraduate students to a global audience. For you, as a researcher, OPUS increases the visibility and accessibility of your research by making it openly available regardless of where you choose to publish.
Items in OPUS are enhanced with high quality metadata and seeded to search engines such as Google Scholar as well as being linked to your UTS research profile, increasing discoverability and opportunities for citation of your work and collaboration. In addition, works in OPUS are preserved for long-term access and discovery.
The UTS Open Access Policy requires UTS research outputs to be openly available via OPUS. Depositing your work in OPUS also assists you in complying with ARC, NHMRC and other funder Open Access policies. Providing Open Access to your research outputs through OPUS not only ensures you comply with these important policies, but increases opportunities for other researchers to cite and build upon your work.
OPUS archives UTS research submitted for the UTS Research Output Collection (UTS ROC) and Excellence in Research for Australia (ERA). It also stores digital theses and forms of scholarship that do not usually see formal publication.
When you claim (or enter) your research in Symplectic Elements, simply upload a copy of your work which can be made openly available. Symplectic provides information on which version of your work to upload. If you are unsure, please supply a copy of the Accepted Manuscript version. Ensure you check the box to "agree to the OPUS license terms".
Once uploaded, your works are automatically sent to OPUS and placed temporarily in Closed Access until reviewed by UTS Library staff.
Once items are cleared of copyright constraints and/or publisher embargoes, your work is moved to Open Access and made accessible to the public.
Instructions are available from the Symplectic User Guide or contact email@example.com for further information.