Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/8978
Title: Enhancing multiphoton upconversion through energy clustering at sublattice level
Authors: Wang, J
Deng, R
Macdonald, MA
Chen, B
Yuan, J 
Wang, F
Chi, D
Hor, ATS
Zhang, P
Liu, G
Han, Y
Liu, X
Issue Date: 2014
Publisher: Nature Publishing Group
Source: Nature materials, 2014, v. 13, no. 2, p. 157-162 How to cite?
Journal: Nature Materials 
Abstract: The applications of lanthanide-doped upconversionnanocrystals in biological imaging, photonics, photovoltaics and therapeutics have fuelled a growing demand for rational control over the emission profiles of the nanocrystals. A common strategy for tuning upconversion luminescence is to control the doping concentration of lanthanide ions. However, the phenomenon of concentration quenching of the excited state at high doping levels poses a significant constraint. Thus, the lanthanide ions have to be stringently kept at relatively low concentrations to minimize luminescence quenching. Here we describe a new class of upconversion nanocrystals adopting an orthorhombic crystallographic structure in which the lanthanide ions are distributed in arrays of tetrad clusters. Importantly, this unique arrangement enables the preservation of excitation energy within the sublattice domain and effectively minimizes the migration of excitation energy to defects, even in stoichiometric compounds with a high Yb 3+ content (calculated as 98 mol%). This allows us to generate an unusual four-photon-promoted violet upconversion emission from Er 3+ with an intensity that is more than eight times higher than previously reported. Our results highlight that the approach to enhancing upconversion through energy clustering at the sublattice level may provide new opportunities for light-triggered biological reactions and photodynamic therapy.
URI: http://hdl.handle.net/10397/8978
ISSN: 1476-1122
DOI: 10.1038/nmat3804
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