Photoluminescence tuning via cation substitution in oxonitridosilicate phosphors: DFT calculations, different site occupations, and luminescence mechanisms

Guogang Li, Chun Che Lin, Wei Ting Chen, Maxim S. Molokeev, Victor V. Atuchin, Chang Yang Chiang, Wuzong Zhou, Chin Wei Wang, Wen Hsien Li, Hwo Shuenn Sheu, Ting Shan Chan, Chonggeng Ma, Ru Shi Liu

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137 Citations (Scopus)

Abstract

Tuning and optimizing luminescent properties of oxonitridosilicates phosphors are important for white light-emitting diode (WLED) applications. To improve the color rendering index, correlated color temperature and thermal stability of layer-structured MSi2O2N2:Eu (M = Sr, Ba) phosphors, cation substitutions have been used to adjust their luminescent properties. However, the underlying mechanisms are still unclear. In this research, a series of (Sr1-xBax)Si2O 2N2:Eu (0 ≤ x ≤ 1) compounds were prepared by solid-state reaction, after which systematic emission variations were investigated. The crystal structures of (Sr1-xBax)Si 2O2N2:Eu (0 ≤ x ≤ 1) are nominally divided into three sections, namely, Phase 1 (0 ≤ x ≤ 0.65), Phase 2 (0.65 < x < 0.80), and Phase 3 (0.80 ≤ x ≤ 1) based on the X-ray diffraction measurements. These experimental results are further confirmed by optimizing the crystal structure data with first-principle calculations. Continuous luminescence adjustments from green to yellow are observed in Phase 1 with gradual replacement of Sr2+ with Ba2+, and the abnormal redshift is clarified through extended X-ray absorption fine structure analysis. Sr(Eu)-O/N bond length shrinkage in local structure causes the redshift emission, and the corresponding luminescence mechanism is proposed. Controllable luminescence in Phase 2 (from blue to white) and Phase 3 (from cyan to yellowish green) are observed. Based on the high-resolution transmission electron microscopy and selected area electron diffraction analysis, the two kinds of luminescence tuning are attributed to phase segregation. This study serves as a guide in developing oxonitride luminescent materials with controllable optical properties based on variations in local coordination environments through cation substitutions.

Original languageEnglish
Pages (from-to)2991-3001
Number of pages11
JournalChemistry of Materials
Volume26
Issue number9
DOIs
Publication statusPublished - May 13 2014
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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    Li, G., Lin, C. C., Chen, W. T., Molokeev, M. S., Atuchin, V. V., Chiang, C. Y., Zhou, W., Wang, C. W., Li, W. H., Sheu, H. S., Chan, T. S., Ma, C., & Liu, R. S. (2014). Photoluminescence tuning via cation substitution in oxonitridosilicate phosphors: DFT calculations, different site occupations, and luminescence mechanisms. Chemistry of Materials, 26(9), 2991-3001. https://doi.org/10.1021/cm500844v