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Optical Properties of Red-Emitting Rb₂Bi(PO₄)(MoO₄):Eu³⁺ Powders and Ceramics with High Quantum Efficiency for White LEDs.

ABSTRACT: There are several key requirements that a very good LED phosphor should meet, i.e., strong absorption, high quantum efficiency, high colour purity, and high luminescence quenching temperature. The reported Rb₂Bi(PO₄)(MoO₄):Eu³⁺ phosphors have all these properties. The Rb₂Bi(PO₄)(MoO₄):Eu³⁺ phosphors emit bright red light if excited with near-UV radiation. The calculated colour coordinates show good stability in the 77-500 K temperature range. Moreover, sample doped with 50% Eu³⁺ possesses quantum efficiency close to unity. Besides the powder samples, ceramic disks of Rb₂Eu(PO₄)(MoO₄) specimen were also prepared, and the red light sources from these disks in combination with near-UV emitting LED were fabricated. The obtained results indicated that ceramic disks efficiently absorb the emission of 375 and 400 nm LED and could be applied as a red component in phosphor-converted white LEDs.

SUBMITTER: Grigorjevaite J

PROVIDER: S-EPMC6804156 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Optical Properties of Red-Emitting Rb2Bi(PO4)(MoO4):Eu3+ Powders and Ceramics with High Quantum Efficiency for White LEDs.

Grigorjevaite Julija J Ezerskyte Egle E Minderyte Agne A Stanionyte Sandra S Juskenas Remigijus R Sakirzanovas Simas S Katelnikovas Arturas A

Materials (Basel, Switzerland) 20191008 19

There are several key requirements that a very good LED phosphor should meet, i.e., strong absorption, high quantum efficiency, high colour purity, and high luminescence quenching temperature. The reported Rb2Bi(PO4)(MoO4):Eu3+ phosphors have all these properties. The Rb2Bi(PO4)(MoO4):Eu3+ phosphors emit bright red light if excited with near-UV radiation. The calculated colour coordinates show good stability ...[more]

PMID: 31597346

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Project description:Eu3+-activated Ba2Y5B5O17 (Ba2Y5-x Eu x B5O17; x = 0.1-1) red-emitting phosphors were synthesized by the conventional high temperature solid-state reaction method in an air atmosphere. Powder X-ray diffraction (XRD) analysis confirmed the pure phase formation of the as-synthesized phosphors. Morphological studies were performed using field emission-scanning electron microscopy (FE-SEM). The photoluminescence spectra, lifetimes, color coordinates and internal quantum efficiency (IQE) as well as the temperature-dependent emission spectra were investigated systematically. Upon 396 nm excitation, Ba2Y5-x Eu x B5O17 showed red emission peaking at 616 nm which was attributed to the 5D0 → 7F2 electric dipole transition of Eu3+ ions. Meanwhile, the influences of different concentrations of Eu3+ ions on the PL intensity were also discussed. The optimum concentration of Eu3+ ions in the Ba2Y5-x Eu x B5O17 phosphors was found to be x = 0.8. The concentration quenching mechanism was attributed to the dipole-dipole interaction and the critical distance (R c) for energy transfer among Eu3+ ions was determined to be 5.64 Å. The asymmetry ratio [(5D0 → 7F2)/(5D0 → 7F1)] of Ba2Y4.2Eu0.8B5O17 phosphors was calculated to be 3.82. The fluorescence decay lifetimes were also determined for Ba2Y5-x Eu x B5O17 phosphors. In addition, the CIE color coordinates of the Ba2Y4.2Eu0.8B5O17 phosphors (x = 0.653, y = 0.345) were found to be very close to the National Television System Committee (NTSC) standard values (x = 0.670, y = 0.330) of red emission and also showed high color purity (∼94.3%). The corresponding internal quantum efficiency of the Ba2Y4.2Eu0.8B5O17 sample was measured to be 47.2%. Furthermore, the as-synthesized phosphors exhibited good thermal stability with an activation energy of 0.282 eV. The above results revealed that the red emitting Ba2Y4.2Eu0.8B5O17 phosphors could be potential candidates for application in near-UV excited white light emitting diodes.

Dataset Information

Optical Properties of Red-Emitting Rb₂Bi(PO₄)(MoO₄):Eu³⁺ Powders and Ceramics with High Quantum Efficiency for White LEDs.

Publications

Optical Properties of Red-Emitting Rb<sub>2</sub>Bi(PO<sub>4</sub>)(MoO<sub>4</sub>):Eu<sup>3+</sup> Powders and Ceramics with High Quantum Efficiency for White LEDs.

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