Enhancing multiphoton upconversion through energy clustering at sublattice level

Juan Wang, Renren Deng, Mark A B Macdonald, Bolei Chen, Jikang Yuan, Feng Wang, Dongzhi Chi, Andy Sum Andy Hor, Peng Zhang, Guokui Liu, Yu Han, Xiaogang Liu

Research output: Contribution to journalArticlepeer-review

401 Scopus citations

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. © 2014 Macmillan Publishers Limited. All rights reserved.
Original languageEnglish (US)
Pages (from-to)157-162
Number of pages6
JournalNature Materials
Volume13
Issue number2
DOIs
StatePublished - Nov 24 2013

ASJC Scopus subject areas

  • Mechanics of Materials
  • Materials Science(all)
  • Chemistry(all)
  • Mechanical Engineering
  • Condensed Matter Physics

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