Eu2+ Stabilized at Octahedrally Coordinated Ln3+ Site Enabling Red Emission in Sr3LnAl2O7.5 (Ln = Y or Lu) Phosphors. Issue 9 (16th February 2021)

• Record Type: Journal Article
• Authors: Hu, Tao; Gao, Yan; Molokeev, Maxim S.; Xia, Zhiguo; Zhang, Qinyuan
• Is Part Of: Advanced optical materials. Volume 9:Issue 9(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-16
• Subjects: Eu 2+ -- photoluminescence -- red phosphor -- site occupancy; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.202100077
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: Red spectrum loss in phosphor‐converted light‐emitting diodes (pc‐LEDs) restricts high‐quality warm‐white lighting. Herein, two blue‐light excitable red‐emitting Sr3 LnAl2 O7.5 :Eu (Ln = Y or Lu) phosphors are reported, and red emission originating from an unprecedented substitution model, with Eu 2+ occupied sixfold octahedrally coordinated lanthanide (Ln 3+ ) sites is demonstrated. Site occupancy identification reveals that three different sites are occupied by Eu 2+ and one distinct site is occupied by Eu 3+, and the Eu 2+ stabilized at Ln 3+ site accompanied by Eu 3+ selectively occupies at Sr 2+ site as a charge compensator. An anomalous prolonged Eu 2+ ‐photoluminescence decay emission with increasing temperature in the low‐temperature region is demonstrated. This accounts for the trapped electrons, which are thermally released from shallow traps and eventually populate the Eu 2+ 5d level to form an excited‐state Eu 2+ . The findings help better understand Eu 2+ occupancy and luminescence. These also provide a new perspective for the exploration of novel Eu 2+ activated oxide‐based red phosphor for pc‐LEDs. Abstract : Red emission of Eu 2+ in oxide‐based phosphor is realized based on Eu 2+ substitution at octahedrally coordinated Ln 3+ site. The site occupancies, site symmetries, and luminescence excited‐state dynamics of the red phosphor are analyzed, providing deep understanding of Eu 2+ luminescence in solid‐state compound.