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Highly Luminous N 3- -Substituted Li 2 MSiO 4-δ N 2/3δ :Eu 2+ (M = Ca, Sr, and Ba) for White NUV Light-Emitting Diodesoa mark
  • Kim, Donghyeon ;
  • Ji, Choon Woo ;
  • Lee, Jungjun ;
  • Bae, Jong Seong ;
  • Hong, Tae Eun ;
  • Ahn, Sung Il ;
  • Chung, In ;
  • Kim, Seung Joo ;
  • Park, Jung Chul
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Publication Year
2019-05-13
Journal
ACS Omega
Publisher
American Chemical Society
Citation
ACS Omega, Vol.4 No.5, pp.8431-8440
All Science Classification Codes (ASJC)
Chemistry (all)Chemical Engineering (all)
Abstract
The N 3- -substituted Li 2 MSiO 4 :Eu 2+ (M = Ca, Sr, and Ba) phosphors were systematically prepared and analyzed. Secondary-ion mass spectroscopy measurements revealed that the average N 3- contents are 0.003 for Ca, 0.009 for Sr, and 0.032 for Ba. Furthermore, the N 3- incorporation in the host lattices was corroborated by infrared and X-ray photoelectron spectroscopies. From the photoluminescence spectra of Li 2 MSiO 4 :Eu 2+ (M = Ca, Sr, and Ba) phosphors before and after N 3- doping, it was verified that the enhanced emission intensity of the phosphors is most likely due to the N 3- doping. In Li 2 MSiO 4 :Eu 2+ (M = Ca, Sr, and Ba) phosphors, the maximum wavelengths of the emission band were red-shifted in the order Ca < Ba < Sr, which is not consistent with the trend of crystal field splitting: Ba < Sr < Ca. This discrepancy was clearly explained by electron-electron repulsions among polyhedra, LiO 4 -MO n , SiO 4 -MO n , and MO n -M'O n associated with structural difference in the host lattices. Therefore, the energy levels associated with the 4f 6 5d energy levels of Eu 2+ are definitely established in the following order: Li 2 CaSiO 4 :Eu 2+ > Li 2 BaSiO 4 :Eu 2+ > Li 2 SrSiO 4 :Eu 2+ . Furthermore, using the Williamson-Hall (W-H) method, the determined structural strains of Li 2 MSiO 4 :Eu 2+ (M = Ca, Sr, and Ba) phosphors revealed that the increased compressive strain after N 3- doping induces the enhanced emission intensity of these phosphors. White light-emitting diodes made by three N 3- -doped phosphors and a 365 nm emitting InGaN chip showed the (0.333, 0.373) color coordinate and high color-rendering index (R a = 83). These phosphor materials may provide a platform for development of new efficient phosphors in solid-state lighting field.
ISSN
2470-1343
Language
eng
URI
https://aurora.ajou.ac.kr/handle/2018.oak/30721
https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85065719036&origin=inward
DOI
https://doi.org/10.1021/acsomega.8b03489
Journal URL
pubs.acs.org/journal/acsodf
Type
Article
Funding
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant 2017R1D1A1B03034550). S.-J. Kim, one of the authors, acknowledges the partial supported by the GRRC program of Gyeonggi province (GRRC-Ajou-2016B02).
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Kim, Seung-Joo Image
Kim, Seung-Joo김승주
Department of Chemistry
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