Enhanced photoluminescence emission and thermal stability from introduced cation disorder in phosphors
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Optimizing properties of phosphors for use in white-light‒emitting diodes (WLEDs) is an important materials challenge. Most phosphors have a low level of lattice disorder due to mismatch between the host and activator cations. Here we show that deliberate introduction of high levels of cation disorder leads to significant improvements in quantum efficiency, stability to thermal quenching, and emission lifetime in Sr1.98-x(Ca0.55Ba0.45)xSi5N8:Eu0.02 (x = 0 ‒ 1.5) phosphors. Replacing Sr by a (Ca0.55Ba0.45) mixture with the same average radius increases cation size variance resulting in photoluminescence emission increases of 20‒26% for the x = 1.5 sample relative to the x = 0 parent across the 25‒200 °C range that spans WLED working temperatures. Cation disorder suppresses nonradiative processes through disruption of lattice vibrations and creates deep traps that release electrons to compensate for thermal quenching. Introduction of high levels of cation disorder may thus be a very useful general approach for improving the efficiency of luminescent materials.
Lin , C C , Tsai , YT , Johnston , H , Fang , MH , Yu , F , Zhou , W , Whitfield , P , Li , Y , Wang , J , Liu , RS & Attfield , J P 2017 , ' Enhanced photoluminescence emission and thermal stability from introduced cation disorder in phosphors ' , Journal of the American Chemical Society , vol. 139 , no. 34 , pp. 11766-11770 . https://doi.org/10.1021/jacs.7b04338
Journal of the American Chemical Society
Copyright © 2017 American Chemical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1021/jacs.7b04338
DescriptionThis work was supported by the Ministry of Science and Technology of Taiwan (Contract No. MOST 104‒2113‒M‒002‒012‒MY3), EPSRC and STFC, UK. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.
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