Red emission generation through highly efficient energy transfer from Ce(3+) to Mn(2+) in CaO for warm white LEDs.
Red emission generation through highly efficient energy transfer from Ce(3+) to Mn(2+) in CaO for warm white LEDs.
复制标题
DOI：
10.1039/c5dt04341g
复制
发表时间：
2016-01
影响因子：
4
通讯作者：
Leyu Feng;Z. Hao;Xia Zhang;Liangliang Zhang;G. Pan;Yongshi Luo;Ligong Zhang;H. Zhao;Jiahua Zhang
中科院分区：
文献类型：
--
作者：
Leyu Feng;Z. Hao;Xia Zhang;Liangliang Zhang;G. Pan;Yongshi Luo;Ligong Zhang;H. Zhao;Jiahua Zhang
采用固相反应法合成了不同Mn（2+）浓度的CaO：Ce（3+），Mn（2+）荧光粉。观察到从Ce（3+）到Mn（2+）的有效能量转移，并且它允许CaO：Ce（3+），Mn（2+）的发射颜色随着Mn（2+）浓度的增加和在蓝光激发下从黄色（由Ce（3+）贡献）连续调谐到红色（由Mn（2+）贡献）。当Mn（2+）浓度≥0.014时，红色发光占主导地位，能量转移效率高于87%，当Mn（2+）浓度仅为0.02时，能量转移效率可高达94%。确定了Ce（3+）-Mn（2+）能量转移的临界距离为10.5 μ m。随着Mn（2+）浓度的增加，Ce（3+）发光强度的衰减速度比其寿命的衰减速度快。对这一特征的分析表明，当Ce（3+）-Mn（2+）距离小于7.6 μ m时，Ce（3+）的激发能可以完全转移到Mn（2+）上。将InGaN蓝光LED芯片与两种荧光粉（YAG：Ce（3+）黄色荧光粉和CaO：0.007Ce（3+），0.014Mn（2+）红色荧光粉）的混合物集成在一个封装中，制成了一种暖白色LED，其CIE色坐标为（x = 0.37，y = 0.35），相关色温为3973 K，显色指数为83.1。结果表明，CaO：Ce（3+），Mn（2+）可作为蓝光暖白色LED的红色荧光粉。
CaO:Ce(3+),Mn(2+) phosphors with various Mn(2+) concentrations were synthesized by a solid state reaction method. Efficient energy transfer from Ce(3+) to Mn(2+) was observed and it allows the emission color of CaO:Ce(3+),Mn(2+) to be continuously tuned from yellow (contributed by Ce(3+)) to red (by Mn(2+)) with an increase in Mn(2+) concentration and upon blue light excitation. The red emission becomes dominant when the Mn(2+) concentration is ≥0.014 with an energy transfer efficiency higher than 87% which can reach as high as 94% for a Mn(2+) concentration of only 0.02. A critical distance of 10.5 Å for the Ce(3+)-Mn(2+) energy transfer was determined. A faster decrease of Ce(3+) luminescence intensity in comparison with its lifetime was observed on increasing the Mn(2+) concentration. The analysis of this feature reveals that the Ce(3+) excitation energy can be completely transferred to Mn(2+) if the Ce(3+)-Mn(2+) distance is shorter than 7.6 Å. A warm white LED was fabricated through integrating an InGaN blue LED chip and a blend of two phosphors (YAG:Ce(3+) yellow phosphor and CaO:0.007Ce(3+),0.014Mn(2+) red phosphor) into a single package, which has CIE chromaticity coordinates of (x = 0.37, y = 0.35), a correlated color temperature of 3973 K and a color rendering index of 83.1. The results indicate that CaO:Ce(3+),Mn(2+) may serve as a potential red phosphor for blue LED based warm white LEDs.