研究目的
To enhance the absorption at an excitation wavelength of around 420 nm in Mn4+-doped MgO-MgF2-GeO2 (MGF: Mn4+) phosphors for white LEDs with wider color reproduction gamut.
研究成果
The Sc-co-doped MGF:Mn4+ phosphors showed better optical properties, specifically at the Sc2O3 molar ratio of 0.01, with an IQE increase up to 55%. These phosphors maintained excellent thermal stability even up to 200 °C and exhibited superior color reproduction coverage according to the NTSC, BT.2020, and IES TM-30 standards.
研究不足
The low absorption of the MGF:Mn4+ phosphor around 450 nm is relatively low, which could limit its application in some LED designs.
1：Experimental Design and Method Selection:
The solid-state reaction method was used to synthesize the red phosphor. The starting materials for synthesizing MGF:Mn4+ were MgO, MgF2, GeO2, and Mn2O3 and metal oxide A2O3 (A: Sc, Lu, Y, La). The mixture was sintered at 1100 °C for 5 h in air.
2：Sample Selection and Data Sources:
The prepared phosphor was analyzed by powder X-ray diffraction (XRD) to identify its phase and crystal structure. The room temperature photo-luminescent emission (PL) and excitation (PLE) spectra were recorded using a xenon lamp.
3：List of Experimental Equipment and Materials:
Powder X-ray diffraction (XRD) (D8 Advance, Bruker, Germany), xenon lamp (PSI, Korea), BaSO4-coated integrating sphere with a photomultiplier tube and a xenon lamp (PSI, Korea), Hitachi F-7000 for temperature-dependent PL characteristics.
4：Experimental Procedures and Operational Workflow:
The mixture was blended in isopropyl alcohol, dried, sintered, and then cooled down to room temperature. The phosphor-converted white LEDs were fabricated by coating the set of phosphors on the 450 nm blue-emitting chip.
5：Data Analysis Methods:
The ratio of absorption and the quantum efficiency were measured using a BaSO4-coated integrating sphere. The temperature-dependent PL characteristics of the samples were examined at different temperatures ranging from 25 to 200 °C.
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