Luminescence color tuning and energy transfer properties in (Sr, Ba)2LaGaO5:Bi3+, Eu3+ solid solution phosphors: realization of single-phased white emission for WLEDs. Issue 43 (22nd October 2019)

• Record Type: Journal Article
• Authors: Liu, Dongjie; Dang, Peipei; Yun, Xiaohan; Li, Guogang; Lian, Hongzhou; Lin, Jun
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 43(2019)
• Page Start: 13536
• Page End: 13547
• Publication Date: 2019-10-22
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9tc04938j
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Controllable emission tuning from bluish-green to red was achieved by Ba 2+ /Sr 2+ substitution and Bi 3+ → Eu 3+ energy transfer. Abstract : Recently, controllable luminescence tuning and single-phased white light emission have been extensively studied to improve the luminescence performances of phosphors for white light-emitting diodes (WLEDs). In this work, the controllable photoluminescence tuning from bluish-green to red was successfully achieved in Bi 3+, Eu 3+ -codoped Sr2− y Ba y LaGaO5 solid solutions, combining the effects of crystallographic site engineering and energy transfer. The phase composition and structural variation of the designed phosphors were thoroughly analyzed through X-ray powder diffraction (XRD) and Rietveld refinement. The effects of cation substitutions on the photoluminescence properties were investigated in detail and the corresponding mechanism was proposed. A regular red-shift of Sr2− y Ba y LaGaO5 :0.02Bi 3+ in the bluish-green region could be observed when Sr 2+ was substituted by Ba 2+, which is attributed to the crystal field splitting and nephelauxetic effect. The red-shift of emission of Ba2 LaGaO5 :0.02Bi 3+ phosphor with gradually increasing excitation wavelength reveals that Bi 3+ ions occupy different cation sites to form multiple luminescent centers. Besides, the efficient energy transfer was designed and successfully realized in Sr2− y Ba y LaGaO5 :0.02Bi 3+, z Eu 3+ ( y = 0–2.0; z = 0–0.20) samples. The energy transfer efficiency can reach up to 88%, 91% and 77% at z = 0.20 for y = 0, 1.0 and 2.0, respectively. Moreover, the thermal quenching behaviors of the studied phosphors reveal that the codoping of Eu 3+ could efficiently improve the thermal stability of Sr2 LaGaO5 :0.02Bi 3+ phosphor. Finally, the WLED devices were fabricated by composing 370 nm UV chips and single-phased Sr2− y Ba y LaGaO5 :0.02Bi 3+, 0.05Eu 3+ ( y = 0, 1.0, 2.0) phosphors. The as-fabricated devices presented relatively excellent EL performances, the color coordinates of which all locate in the warm white light region. These results indicate the as-prepared Sr2− y Ba y LaGaO5 :Bi 3+, Eu 3+ phosphors can be potential candidates for color tuning and efficient single-phased white emission in UV-based WLED lighting applications.