Tailoring of White Luminescence in a NaLi3SiO4:Eu2+ Phosphor Containing Broad‐Band Defect‐Induced Charge‐Transfer Emission. Issue 29 (6th June 2021)

• Record Type: Journal Article
• Authors: Zhao, Ming; Yang, Zhiyu; Ning, Lixin; Xia, Zhiguo
• Is Part Of: Advanced materials. Volume 33:Issue 29(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-06
• Subjects: charge‐transfer emission -- light‐emitting diodes -- white luminescence; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202101428
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Single‐component materials with white‐light emission are ideal for lighting applications. However, it is very challenging to achieve white luminescence in single‐dopant activated solid phosphors. Herein, white NaLi3 Si1− x O4 :Eu 2+ materials are designed via defect engineering and synthesized by reducing the Si content (0.15 ≤ x ≤ 0.25). Stochiometric NaLi3 SiO4 :Eu 2+ exhibits a narrow‐band blue emission at 469 nm, ascribed to the 5d → 4f transition of Eu 2+ at highly symmetric cuboid Na sites, while samples with Si content reduced by 15–25% display white emission with two peaks at 472 nm and 585 nm. The newly appeared broadband yellow peak arises from charge‐transfer transitions involving Eu 2+ and nearby defects, as verified by an unusual bandwidth, a large Stokes shift, and a long decay time. A single‐component white light‐emitting diode device is fabricated by employing a white phosphor to demonstrate a color‐rendering index of 82.9. This result provides a new design strategy for single‐component white‐light materials with broad‐band defect‐induced charge‐transfer emission. Abstract : A single‐component white emitter is developed by introducing defect‐associated charge‐transfer emission in a NaLi3 SiO4 :Eu 2+ phosphor via a facile composition modification strategy. An extra broadband yellow peak (585 nm) appears in addition to the narrow‐band blue emission (472 nm). A single‐component white light‐emitting diode with color‐rendering index of 82.9 is fabricated using the white phosphor.