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NaYF 4 :Yb,Er/NaYF 4 Core/Shell Nanocrystals with High Upconversion Luminescence Quantum Yield
Author(s) -
Homann Christian,
Krukewitt Lisa,
Frenzel Florian,
Grauel Bettina,
Würth Christian,
ReschGenger Ute,
Haase Markus
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201803083
Subject(s) - quantum yield , photon upconversion , materials science , photoluminescence , nanocrystal , yield (engineering) , phosphor , analytical chemistry (journal) , quantum dot , luminescence , nanotechnology , chemistry , optoelectronics , optics , physics , composite material , fluorescence , organic chemistry
Upconversion core/shell nanocrystals with different mean sizes ranging from 15 to 45 nm were prepared via a modified synthesis procedure based on anhydrous rare‐earth acetates. All particles consist of a core of NaYF 4 :Yb,Er, doped with 18 % Yb 3+ and 2 % Er 3+ , and an inert shell of NaYF 4 , with the shell thickness being equal to the radius of the core particle. Absolute measurements of the photoluminescence quantum yield at a series of different excitation power densities show that the quantum yield of 45 nm core/shell particles is already very close to the quantum yield of microcrystalline upconversion phosphor powder. Smaller core/shell particles prepared by the same method show only a moderate decrease in quantum yield. The quantum yield of 15 nm core/shell particles, for instance, is reduced by a factor of three compared to the bulk upconversion phosphor at high power densities (100 W cm −2 ) and by approximately a factor of 10 at low power densities (1 W cm −2 ).