Trivalent europium-doped strontium molybdate red phosphors in white light-emitting diodes: Synthesis, photophysical properties and theoretical calculations

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• 作者：W.-Q. Yang ; H.-G. Liu ; G.-K. Liu ; Y. Lin ; M. Gao ; X.-Y. Zhao ; W.-C. Zheng ; Y. Chen ; J. Xu ; L.-Z. Li
• 关键词：White LED ; Fluorescent spectra ; Complete diagonalization method ; SrMoO4 ; Eu3+
• 刊名：Acta Materialia
• 出版年：2012
• 出版时间：September, 2012
• 年：2012
• 卷：60
• 期：15
• 页码：5399-5407
• 全文大小：1161 K

文摘

Eu³⁺-doped strontium molybdate red phosphors (Sr_1?xMoO₄:Eu_x (x = 0.01-0.2)) for white light-emitting diodes (LED) were synthesized by the solid-state reaction method. The fluorescent intensities of the as-prepared phosphors were remarkably improved. The excitation and emission spectra demonstrate that these phosphors can be effectively excited by the near-UV light (395 nm) and blue light (466 nm). Their emitted red light peaks are located at 613 nm, and the highest quantum yield value (¦Ç) of the as-grown red phosphor, which is 95.85 % , is much higher than that of commercial red phosphor (77.53 % ). These red phosphors plus commercial yellow powers (1:10) were successfully packaged with the GaN-based blue chips on a piranha frame by epoxy resins. The encapsulated white LED lamps show high performance of the CIE chromaticity coordinates and color temperatures. Moreover, to explain the fluorescent spectra of these phosphors, a complete 3003 ¡Á 3003 energy matrix was successfully built by an effective operator Hamiltonian including free ion and crystal field interactions. For the first time, the fluorescent spectra for Eu³⁺ ion at the tetragonal (S₄) Sr²⁺ site of SrMoO₄ crystal were calculated from a complete diagonalization (of energy matrix) method. The fitting values are close to the experimental results.