兰州大学机构库 >物理科学与技术学院
几种近紫外白光LED用(氮)氧化物发光材料发光性能及能量传递研究
Alternative TitlePhotoluminescence properties and energy transfer of several oxide/oxynitride phosphors for NUV white LEDs
李艳艳
Subtype博士
Thesis Advisor王育华
2017-04-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword白光LED 发光材料 晶体结构 能量传递
Abstract

白光发光二极管(light emitting diode, LED),尤其是荧光转换型LED (phosphor-converted LED, pc-LED),作为一种环境友好型照明光源由于其具有寿命长,能耗低等优点,已经受到了广泛的关注。发光材料作为pc-LED的重要组成部分,极大地影响着LED设备的性能。通常来说,pc-LED有两种实现方法:使用蓝光芯片或近紫外芯片涂覆发光材料。针对目前近紫外 (near ultraviolet, NUV) (350-420 nm) LED用发光材料存在的问题,设计并制备了几种新型的发光材料,并对其发光性能及能量传递机理作了深入的研究。主要工作总结如下:(1)通过高温固相法合成了近紫外白光LED用蓝绿色发光材料Ca15Si20O10N30:Ce3+。随着Ce3+浓度的增加,其发射峰值可以从470 nm调节到520 nm,这种红移归因于占据不同格位的Ce3+之间的能量传递,可以通过时间分辨光谱及不同监控波长下不同的衰减速率证明。(2)通过高温固相法合成了系列高温相Ba3P4O13:Eu2+黄色发光材料,在近紫外激发下,高温相Ba3P4O13:Eu2+发射出半峰宽为175 nm,峰值在587 nm的宽包,这归属于Eu2+的5d-4f跃迁。高温相Ba3P4O13:Eu2+在近紫外区有很强的吸收,并且几乎在蓝光区域无吸收。其时间分辨光谱的变化表明占据不同Ba2+格位的Eu2+之间有很小的能量传递。除此之外,将高温相Ba3P4O13:Eu2+黄色发光材料与商用BaMgAl10O17:Eu2+蓝色发光材料按一定比例混合后,可以得到色坐标为(0.364,0.357),色温为4354 K的白光。(3)通过高温固相法制备了系列Ce3+, Eu2+共掺的Ca3Si2O4N2发光材料。通过改变Ce3+和Eu2+的比例实现了Ca3Si2O4N2:Ce3+, Eu2+的发光颜色从蓝色变到绿色。与单掺Eu2+的样品相比,共掺样品在近紫外区有更强的吸收,这归因于从Ce3+到Eu2+之间有效的能量传递,其能量传递机理被证明是偶极-偶极作用。(4)通过高温固相法合成了系列Ce3+、Mn2+共掺的CaSr2Al2O6发光材料。Ce3+激活的CaSr2Al2O6在250-420 nm范围内有较强的吸收,在近紫外激发下发射峰值在460 nm的蓝光。在358 nm激发下,随着Mn2+浓度的增加,CaSr2Al2O6:Ce3+, Li+, Mn2+发光材料的颜色可由蓝色调节到红色。当Mn2+的浓度为0.02时,可以得到色坐标为(0.388, 0.323),色温为3284 K的暖白光。通过对系列样品衰减曲线的分析,证明在此基质中,从Ce3+到Mn2+之间的能量传递是四极-四极作用。除此之外,还研究了Eu3+掺杂的CaSr2Al2O6的发光性能。CaSr1.90Al2O6:0.10Eu和Ca0.90Sr2Al2O6:0.10Eu发射光谱的不同表明Eu3+占据了不同对称性格位的Sr2+或Ca2+

Other Abstract

White light-emitting diode (LEDs), especially for phosphor converted LED (pc-LED), as an environmentally friendly lighting system, has attracted much attention due to its long operation lifetime, low energy consumption. Phosphor as an important part of pc-LEDs influenced the properties of LED devices. Generally, two different configurations are possible for pc-white LEDs, based on either a blue LED or a near-ultraviolet (NUV) (350-420 nm) LED. To solve the existed problems of phosphors for NUV LEDs, we designed and synthesized several new phosphors, and systematically investigated the structure, photoluminescence properties and the energy transfer mechanism between the doped ions. The main works are concluded as follows.(1) A blue-green phosphor Ca15Si20O10N30:Ce3+ for NUV white LEDs was synthesized by the solid state reaction method. The maximum emission wavelength of the phosphor can be tuned from about 470 to 520 nm as the content of Ce3+ increases due to the energy transfer between various Ce3+ activators located in different coordination environments, and this was verified by the time-resolved emission spectroscopy and the variation in the decay rate with respect to the detection wavelength.(2) A yellow-emitting high-Ba3P4O13:Eu2+ phosphor was synthesized by the solid state reaction, and the phosphor shows an extreme broad band at around 587 nm with a full width at half maximum of about 175 nm, which is attributed to the 5d-4f transition of Eu2+ under NUV excitation. This phosphor shows good absorption in the NUV range and nearly no absorption in the blue region. The change in the time-resolved emission spectroscopy indicates the energy transfer between the Eu2+ ions occupying different Ba2+ sites. Moreover, a white light with chromaticity coordinates of (0.364, 0.357) and color temperature of 4354 K was obtained by blending the yellow-emitting high-Ba3P4O13:Eu2+ and the commercial blue-emitting BaMgAl10O17:Eu2+ phosphor.(3) A series of Ce3+, Eu2+ codoped Ca3Si2O4N2 phosphors have been synthesized by the solid state reaction method. Tunable blue to green emitting colors can be obtained by varying the relative ratios of Ce3+ to Eu2+ in Ca3Si2O4N2. Compared with the Eu2+ ion singly doped phosphor, the codoped phosphors have wider absorption in the NUV range and stronger emission of Eu2+, which are attributed to the effective energy transfer from Ce3+ to Eu2+. And the energy transfer mechanism is demonstrated to be a dipole-dipole interaction.(4) A series of single-component Ce3+, Mn2+ ions codoped color-tunable CaSr2Al2O6 phosphors were synthesized by the solid state reaction method. The Ce3+ activated phosphors have strong absorption in the range of 250-420 nm and can give a blue emission centered at about 460 nm. When Mn2+ ions are codoped, the emission of CaSr2Al2O6:Ce3+, Li+, Mn2+ phosphors can be tuned from blue to red through adjusting the doping content of the Mn2+ ions, under the irradiation of 358 nm. When the concentration of Mn2+ in increased to 0.02, a warm-white light can be obtained with good CIE coordinates of (0.388, 0.323) and a low CCT of 3284K. The energy transfer mechanism from the Ce3+ to Mn2+ ions is demonstrated to be quadrupole-quadrupole interaction based on the analysis of the decay curves of the phosphors. Moreover, the photoluminescence properties of Eu3+ doped CaSr2Al2O6 were also investigated. The difference between the emission spectra of CaSr1.90Al2O6:0.10Eu and Ca0.90Sr2Al2O6:0.10Eu revealed that the Eu3+ ions occupied nonequivalent Sr2+ or Ca2+ sites with different site symmetry.

URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229742
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
李艳艳. 几种近紫外白光LED用(氮)氧化物发光材料发光性能及能量传递研究[D]. 兰州. 兰州大学,2017.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[李艳艳]'s Articles
Baidu academic
Similar articles in Baidu academic
[李艳艳]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[李艳艳]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.