Importance of long-range channel Sr displacements for the narrow emission in Sr[Li${}_2$Al${}_2$O${}_2$N${}_2$]:Eu${}^{2+}$ phosphor

Abstract

The recently discovered Sr[Li${}_2$Al${}_2$O${}_2$N${}_2$]:Eu${}^{2+}$ red phosphor, candidate for the next generation of eco-efficient white light-emitting diodes, exhibits excellent emission spectral position and exceptionally small linewidth. It belongs to the UCr${}_4$C${}_4$-structure family of phosphors, containing many potential candidates commercial phosphors, whose small linewidth, tentatively ascribed to the high-symmetry cuboid environment of the doping site, has drawn the attention of researchers in the last five years. We use density functional theory, $\Delta$SCF method and configuration coordinate models (CCM) to provide a complete characterization of this material. Using a multi-dimensional CCM, an accurate description of the coupling of the vibronic structure with the electronic 5d$\to$4f transition is obtained, including the partial Huang-Rhys factors and frequency of the dominant modes. We show that, in addition to the first-coordination shell cuboid deformation mode, low-frequency phonon modes involving chains of strontium atoms along the tetragonal axis shape the emission linewidth in Sr[Li${}_2$Al${}_2$O${}_2$N${}_2$]:Eu${}^{2+}$. This finding sheds new light on the emission properties of UCr${}_4$C${}_4$-structure phosphors, possessing similar Ca/Sr/Ba channel. Our approach provides a robust theoretical framework to systematically study the emission spectra of such Eu-doped phosphors, and predict candidates with expected similar or even sharper linewidth.

Published version

References in corpus (5)

• First-principles theory of the luminescence lineshape for the triplet transition in diamond NV centre
• Luminescence quenching via deep defect states: A recombination pathway via oxygen vacancies in Ce-doped YAG
• Vibrational and vibronic structure of isolated point defects: the nitrogen-vacancy center in diamond
• First-principles Study of the Luminescence of Eu2+-doped Phosphors
• First-principles study of Ce${}^{3+}$ doped lanthanum silicate nitride phosphors: Neutral excitation, Stokes shift, and luminescent center identification

Cited by in corpus (3)

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• Optical line shapes of color centers in solids from classical autocorrelation functions