Journal
JOURNAL OF MATERIALS CHEMISTRY C
Volume 6, Issue 48, Pages 13136-13147Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c8tc05171b
Keywords
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Funding
- National Natural Science Foundation of China [51672259, 51672265, 21521092, 51750110511]
- Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences (Wuhan) [NGM2016KF002]
- Key Research Program of Frontier Sciences, CAS [YZDY-SSW-JSC018]
- projects for science and technology development plan of Jilin province [20170414003GH]
- Program for Jiangmen Innovative Research Team [[2017]385]
- major program of basic research and applied research of Guangdong Province [2017KZDXM083]
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Red-emitting phosphors are indispensable compounds which are used to achieve a warm white light in phosphor-converted white light emitting diodes (pc-WLEDs). However, the luminous efficiency and stability of red phosphors are still big challenges. In this work, we developed red-emitting double perovskite phosphors La(2)ATiO(6):Bi3+,Mn4+ (A = Mg, Zn) (LAT:Bi3+,Mn4+) and discuss the relationship between the double perovskite phosphor structure and the luminescence performance in detail. According to the Rietveld refinement results for the La2Mg(1-w)ZnwTiO6:Bi3+,Mn4+ (0 w 1) (LM((1-w))Z(w)T:Bi3+,Mn4+) solid solution, the proposed mechanism of the spectral adjustment is ascribed to the appearance of the phase transition, which results in a lower local structural symmetry of the [LaO12] polyhedron and the variation of the crystal field environment for Mn4+. Notably, this is the first time that the influence of the local structure variation on the luminescence tuning in double perovskite structure phosphors has been revealed, and this could offer guidance for the development of new phosphor system. By designing Mg2+/Zn2+ cation substitution, the internal quantum efficiency (IQE) is remarkably enhanced beyond 20%. In addition, we succeeded in achieving a Bi3+/Mn4+ co-doped energy transfer in the double perovskite structure phosphors. Owing to the Bi3+ Mn4+ energy transfer in LAT, the red emission of the Mn4+ ions could be dramatically enhanced. The energy transfer efficiency of LAT:Bi3+,Mn4+ eventually exceeded 90%. The IQE and the thermal stability were all enhanced by around 30% compared to the non-co-doped samples, respectively. These results indicate that the Bi3+ Mn4+ energy transfer strategy could play a pivotal role in the development of highly efficient red-emitting phosphors. The performance of the fabricated pc-WLEDs devices indicates that LAT:Bi3+,Mn4+ could be a promising red phosphor for near ultraviolet (n-UV) based warm pc-WLEDs.
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