[12p-A303-1~15] 13.8 Optical properties and light-emitting devices

▲ [12p-A303-3] Powder Synthesis and Photoluminescent Properties of Yellow-emitting Ba₅Si₁₁Al₇N₂₅:Eu²⁺ phosphors for White Light-Emitting Diodes

〇(D)Can HE^1,2, Takashi TAKEDA², Zhao-hui HUANG¹, Naoto HIROSAKI² (1.China Univ Of Geosciences (Beijing), 2.NIMS)

Keywords:Powder Synthesis, Photoluminescent Properties, Yellow-emitting phosphors

The single-particle-diagnosis approach is a facile and efficient method to develop novel luminescent materials for solid state lighting. The most critical issue for this method is achieving large-scale industrial production of powder from a single crystal^[1]. The novel nitridoalumosilicate phosphor Ba₅Si₁₁Al₇N₂₅:Eu²⁺ was discovered by the single-particle-diagnosis method^[2]. Differing from most phosphors, the phase-pure powder of Ba₅Si₁₁Al₇N₂₅:Eu²⁺ cannot be obtained by firing the starting materials with the stoichiometric composition of its single crystal. In this work, almost-pure phase Ba₅Si₁₁Al₇N₂₅:Eu²⁺ powder was obtained by optimizing the chemical composition at 1900℃ for 2 hours under 0.92 MPa N₂. Upon excitation with violet light (400nm), the as-prepared sample showed a broad emission band with a maximum emission peak at ~566 nm and a full width at half-maximum (FWHM) of 88 nm. The excitation spectrum ranged from 350 to 550 nm, which indicated that the Ba₅Si₁₁Al₇N₂₅:Eu²⁺ phosphor could be efficiently excited with both near-UV LEDs and blue LEDs. In addition, weak thermal quenching was observed in the Ba₅Si₁₁Al₇N₂₅:1%Eu²⁺ phosphor. When the temperature increased up to 150 °C, the integrated emission intensity of the Ba₅Si₁₁Al₇N₂₅:1%Eu²⁺ phosphor still maintained 94% of the initial intensity at 30 °C. The Ba₅Si₁₁Al₇N₂₅:Eu²⁺ promises to be a new commercial phosphor comparable to YAG:Ce³⁺ for white light-emitting diodes.