Enhanced high-order upconversion luminescence of hexagonal phase NaYF4:Yb3+,Tm3+ crystals coated with homogeneous shell

Huan Chen, Yanbo Lang, Dan Zhao, Chunfeng He, Weiping Qin

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

High-order upconversion luminescence (ultraviolet (UV), violet and blue emissions) of rare earth nanocrystals is quite desirable for photodynamic therapy and near-infrared photocatalysis applications. The hexagonal phase NaYF4:Yb3+,Tm3+/x mmol NaYF4 (x = 0, 0.1, 0.5, and 1) crystals were prepared by a hydrothermal method. With the amount of the shell precursor increasing, the crystals shape changed from hexagonal plate to hexagonal prism gradually, with the particles size increased. After coating a homogeneous inert NaYF4 shell, the high-order upconversion luminescence (1I6 and 1D2 radiative transitions) of all core-shell crystals were enhanced by several times compared with core-only crystals. Impressively, when the amount of the shell precursor was 0.1 mmol, the increased ratio of the emissions from 1I6 and 1D2 were 7.44 and 5.63 times, respectively. With further increasing the amount of the shell precursor, the increased ratio displayed a slight decline. The further photoluminescence decay results were consistent with the upconversion luminescence spectra. We demonstrated that the enhancement of high-order upconversion luminescence was attributed to the well-known surface passivation effect of the homogeneous shell.

Original languageEnglish
Pages (from-to)70-74
Number of pages5
JournalJournal of Fluorine Chemistry
Volume174
DOIs
StatePublished - 1 Jul 2015
Externally publishedYes

Keywords

  • High-order upconversion
  • Homogenous shell
  • NaYF

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