Rare-earth-free red-emitting K2Ge4O9:Mn4+ phosphor excited by blue light for warm white LEDs
Rare-earth-free red-emitting K2Ge4O9:Mn4+ phosphor excited by blue light for warm white LEDs
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DOI：
10.1039/c6cp00168h
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发表时间：
2016-03-21
影响因子：
3.3
通讯作者：
Wang, Yuhua
中科院分区：
文献类型：
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作者：
Ding, Xin;Wang, Qian;Wang, Yuhua
采用传统的高温固相反应，在蓝光激发下成功合成了一系列具有红光发射的K2Ge4O9:Mn4+荧光粉。采用高分辨率透射电镜、扫描电镜和Rietveld细化的x射线粉末衍射研究了K2Ge4O9的结构。通过测量其漫反射光谱、发射光谱、激发光谱、衰减曲线和温度相关光谱，研究了其PL特性。在紫外光或蓝光激发下，KGO:0.1% Mn4+荧光粉能在663 nm处发出红光。Mn4+的临界淬火浓度约为0.1 mol%。Mn4+中心的浓度猝灭机制可能是d-d相互作用。CIE色度坐标和FWHM分别为（0.702,0.296）和20 nm，表明K2Ge4O9:Mn4+具有较高的颜色纯度。通过调整黄色荧光粉和红色荧光粉的重量比，在40ma电流驱动下，采用455nm InGaN蓝色芯片，将黄色荧光粉YAG:Ce3+和红色荧光粉KGO:Mn4+混合在一起，制备出色度坐标为0.405,0.356，CCT为3119 K的白光led。这些结果表明，K2Ge4O9:Mn4+是一种潜在的红色荧光粉，可以与蓝色LED芯片匹配以获得暖白光。
A series of novel K2Ge4O9:Mn4+ phosphors with red emission under blue light excitation have been synthesized successfully by traditional high-temperature solid-state reaction. The structure of K2Ge4O9 has been investigated by high-resolution transmission electron microscopy, scanning electron microscopy and X-ray powder diffraction with Rietveld refinement. The PL properties have been investigated by measuring diffuse reflection spectra, emission spectra, excitation spectra, decay curves and temperature-dependent spectra. The KGO:0.1% Mn4+ phosphor can emit red light peaking at 663 nm under UV or blue light excitation. The critical quenching concentration of Mn4+ was about 0.1 mol%. The concentration quenching mechanism could be a d-d interaction for the Mn4+ center. The CIE chromaticity coordinates and FWHM are (0.702, 0.296) and 20 nm, which demonstrated that the K2Ge4O9:Mn4+ has a high color purity. By tuning the weight ratio of yellow and red phosphors, the fabricated white LEDs, using a 455 nm InGaN blue chip combined with a blend of the yellow phosphor YAG:Ce3+ and the red-emitting KGO:Mn4+ phosphor driven by a 40 mA current, can get white light with chromaticity coordinates (0.405, 0.356) and CCT 3119 K. These results indicated that K2Ge4O9:Mn4+ is a potential red phosphor to match blue LED chips to get warm white light.