Abstract
Red-emitting narrow-band phosphors are of utmost importance for next-generation white-light phosphor-converted light-emitting diodes (pc-wLEDs) for improved efficacy and optimized correlated color temperatures. A promising representative crystallizing in an ordered variant of the UCr4C4 structure type is Sr[Li2Al2O2N2]:Eu2+ (SALON:Eu2+) emitting at a desirable wavelength of 614 nm. Despite an expected eightfold coordination of the Eu2+ ions by four N3− and O2− ions, respectively, the exact local coordination symmetry and a 1:1 ratio between the two types of ligands is not straightforwardly proven by X-ray diffraction. Low-temperature luminescence spectroscopy in conjunction with ligand field theory are powerful alternatives to resolve local features of Eu2+ as its excited 4f65d1 configuration reacts sensitively to the polarity of the ligands. The dominant emission at 614 nm shows pronounced vibronic fine structure at 10 K. In addition, weak emission bands can be resolved at 570 and 650 nm even at a low doping concentration of 0.5 mol% and are assigned to Eu2+ ions being eightfold coordinated by N3− and O2− ions in a ratio different from 1:1. Due to the feature of vierer ring-type channels in SALON:Eu2+, those Eu2+ centers are sufficiently close for mutual energy transfer, which is characterized by time-resolved luminescence at 10 K.
Original language | English |
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Article number | 2202732 |
Number of pages | 11 |
Journal | Advanced Optical Materials |
Volume | 11 |
Issue number | 9 |
DOIs | |
Publication status | Published - 4 May 2023 |
Bibliographical note
Publisher Copyright:© 2023 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH.
Funding
M.S. is grateful for a material cost allowance from the Fonds der Chemischen Industrie e.V. and funding from the "Junges Kolleg" of the North‐Rhine Westphalian Academy of Sciences and Arts. A.G.‐F. acknowledges funding of the project PGC2018‐094783 (MCIU/AEI/FEDER, EU) and Asturias FICYT under grant AYUD/2021/51185 with the support of FEDER funds. Parts of this work are funded by the German Federal Ministry of Economic Affairs and Climate Action (Bundesministerium für Wirtschaft und Klimaschutz) in the frame of the Important Project of Common European Interest (IPCEI) on microelectronics. M.S. is grateful for a material cost allowance from the Fonds der Chemischen Industrie e.V. and funding from the "Junges Kolleg" of the North-Rhine Westphalian Academy of Sciences and Arts. A.G.-F. acknowledges funding of the project PGC2018-094783 (MCIU/AEI/FEDER, EU) and Asturias FICYT under grant AYUD/2021/51185 with the support of FEDER funds. Parts of this work are funded by the German Federal Ministry of Economic Affairs and Climate Action (Bundesministerium für Wirtschaft und Klimaschutz) in the frame of the Important Project of Common European Interest (IPCEI) on microelectronics. Open access funding enabled and organized by Projekt DEAL.
Funders | Funder number |
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Asturias FICYT | AYUD/2021/51185 |
Bundesministerium für Wirtschaft und Klimaschutz | |
German Federal Ministry of Economic Affairs and Climate Action | |
North-Rhine Westphalian Academy of Sciences and Arts | |
North‐Rhine Westphalian Academy of Sciences and Arts | PGC2018‐094783 |
Verband der Chemischen Industrie | |
Ministerio de Ciencia, Innovación y Universidades | |
European Commission | |
European Regional Development Fund | |
Agencia Estatal de Investigación |
Keywords
- Eu
- light-emitting diodes
- narrow-band red emitter
- Sr[Li Al O N ] (SALON)
- UCr C -type phosphors