Fabrication of High Color Rendering Index White Light Emitting Diodes from Gold Nanoclusters

We demonstrated gold nanoclusters as color tunable emissive light converters for the application of white light emitting diodes (WLEDs). A blue LED providing 460 nm to excite gold nanoclusters mixed with UV curable material generates broad bandwidth emission at the visible range. Increasing the amount of gold nanoclusters, the correlated color temperature of WLEDs tuned from cold white to warm white, and also results in the variation of color rendering index (CRI). The highest CRI in the experiment is 92.

Effect of light-emitting diodes with different color rendering indexes on the ocular tissues of rat

AIM:To compare the damage of light-emitting diodes(LEDs)with different color rendering indexes(CRIs)to the ocular surface and retina of rats.METHODS:Totally 20 Sprague-Dawley(SD)rats were randomly divided into four groups:the first group was normal control group without any intervention,other three groups were exposed by LEDs with low(LED-L),medium(LED-M),and high(LED-H)CRI respectively for 12 h a day,continuously for 4 wk.The changes in tear secretion(Schirmer I test,SIt),tear film break-up time(BUT),and corneal fluorescein sodium staining(CFS)scores were compared at different times(1 d before experiment,2 and 4 wk after the experiment).The histopathological changes of rat lacrimal gland and retina were observed at 4 wk,and the expressions of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in lacrimal gland were detected by immunofluorescence method.RESULTS:With the increase of light exposed time,the CFS value of each light exposed group continued to increase,and the BUT and SIt scores continued to decrease,which were different from the control group,and the differences between the light exposed groups were statistically significant.Hematoxylin-eosin(HE)results showed that the lacrimal glands of each exposed group were seen varying degrees of acinar atrophy,vacuoledistribution,increasing of eosinophil granules,etc.;the retina showed obvious reduction of photoreceptor cell layer and changes in retinal thickness;LED-L group has the most significant change in all tests.Immunofluorescence suggested that the positive expressions of TNF-αand IL-6 in the lacrimal glands of each exposed group were higher than those of the control group.CONCLUSION:LED exposure for 4 wk can cause the pathological changes of lacrimal gland and retina of rats,and increase the expression of TNF-αand IL-6 in lacrimal gland,the degree of damage is negatively correlated with the CRI.

Very-High Color Rendering Index Hybrid White Organic Light-Emitting Diodes with Double Emitting Nanolayers

A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,000 cd/m2. A peak color rendering index of 90 and a relatively stable color during a wide range of luminance were obtained. In addition, it was demonstrated that the 4,40,400-tri(9-carbazoyl) triphenylamine host influenced strongly the performance of this WOLED.These results may be beneficial to the design of both material and device architecture for high-performance WOLED.

High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

Levofloxacin （LOFX）, which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes （OLEDs）. In this paper, the fabricated white OLED contains a 452-nm blue emitting layer （thickness of 30 nm） with 1 wt% LOFX doped in CBP （4,4＇-bis（carbazol-9-yl）biphenyl） host and a 584-nm orange emitting layer （thickness of 10 nm） with 0.8 wt% DCJTB （4-（dicyanomethylene）-2-tert-butyl-6-（1,1,7,7- tetramethyljulolidin-4-yl-vinyl）-4H-pyran） doped in CBE which are separated by a 20-nm-thick buffer layer of TPBi （2,2＇,2＂-（benzene-1,3,5-triyl）-tri（1-phenyl-lH-benzimidazole）. A high color rendering index （CRI） of 84.5 and CIE chromaticity coordinates of （0.33, 0.32）, which is close to ideal white emission CIE （0.333, 0.333）, are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs.

High efficient and high color rendering index white organic light-emitting diodes

We have fabricated high-efficient white organic light-emitting diodes （WOLEDs） using two types of electron transport materials with different electron mobility. The effect of the electron mobility on the device performance is discussed. In addition, to generate the desired white emission and high color rendering index, we perform the structure design of OLED, in which the functions of co-host of blue and green dopants on chromatic-stability are investigated. Experimental results find that the maximum color rendering index reaches as high as 91 at the voltage of 8 V.

High recorded color rendering performance of single-structured Ce,Mn:Y_(3)(Al,Sc)_(2)Al_(3)O_(12)phosphor ceramics for high-power white LEDs/LDs

Achieving a high color rendering index(CRI)and luminous stability in single-structured Ce:Y_(3)Al_(5)O_(12)(Ce:YAG)phosphor ceramics(PCs)is crucial for high-power white light-emitting diodes or laser diodes(LEDs/LDs).However,cyan valleys and insufficient amounts of the red component in the Ce:YAG emission spectra significantly limit their real applications.In this work,a series of Ce,Mn:Y_(3)(Al,Sc)_(2)Al_(3)O_(12)(Ce,Mn:YSAG)PCs were fabricated by vacuum sintering,and efficient spectral regulation was realized for full-color lighting.The cyan valley was filled by the blueshifted emission peak of Ce^(3+)via Sc^(3+)doping.The orange‒red emission at approximately 580 nm was effectively supplemented via Mn^(2+)doping.In particular,CRI of Ce,Mn:YSAG increased from 56.4 to 85.8,a 52%increase compared with that of Ce:YAG under high-power LED excitation,and the operating temperature was stable at approximately 50℃for long working time.Moreover,CRI of 80.9 could still be obtained for PC-based white LDs.These results indicated that Ce,Mn:YSAG PC,which has excellent CRI and luminous stability,is an extremely promising color convertor for high-power white LEDs/LDs.

NaYSiO_(4)∶Ce^(3+)蓝色荧光粉的发光性质及其在白光发光二极管上的应用

采用高温固相法合成了NaYSiO_(4)∶xCe^(3+)(0.01≤x≤0.05)系列蓝色荧光粉。NaYSiO_(4)∶xCe^(3+)荧光粉在250~360 nm之间的宽带吸收能与紫外LED芯片很好地匹配。NaYSiO_(4)∶xCe^(3+)荧光粉中存在多个Ce^(3+)离子荧光中心,且在紫外光激发下表现出峰值波长位于414 nm附近的宽带蓝光发射。NaYSiO_(4)∶0.02Ce^(3+)荧光粉在300~350 nm紫外光激发下量子效率在25%以上。NaYSiO_(4)∶0.02Ce^(3+)荧光粉表现出优良的化学稳定性,在水中浸泡14 d后荧光强度和量子效率几乎不变。将NaYSiO_(4)∶0.02Ce^(3+)蓝色荧光粉、商用(Sr,Ba)_2SiO_(4)∶Eu^(2+)绿色荧光粉和商用(Ca,Sr)AlSiN_(3)∶Eu^(2+)红色荧光粉涂覆于310 nm紫外LED芯片上制备得到了显色指数高达95的LED器件。当驱动电流从50 mA逐渐增大到300 mA时,制备的LED器件表现出稳定的暖白光发射,其色坐标几乎不变。上述结果说明,本研究报道的NaYSiO_(4)∶0.02Ce^(3+)蓝色荧光粉在紫外LED芯片驱动的白光发光二极管照明上有着潜在应用价值。

Efficient spectral regulation in Ce:Lu_(3)(Al,Cr)_(5)O_(12) and Ce:Lu_(3)(Al,Cr)_(5)O_(12)/Ce:Y_(3)Al_(5)O_(12) transparent ceramics with high color rendering index for high-power white LEDs/LDs

Realizing a high color rendering index(CRI)in Ce:LuAG transparent ceramics(TCs)with desired thermal stability is essential to their applications in white LEDs/LDs as color converters.In this study,based on the scheme of configuring the red component by Cr^(3+) doping,an efficient spectral regulation was realized in Ce,Cr:LuAG TCs.A unilateral shift phenomenon could be observed in both photoluminescence(PL)and photoluminescence excitation(PLE)spectra of TCs.By constructing TC-based white LED/LD devices in a remote excitation mode,luminescence properties of Ce,Cr:LuAG TCs were systematically investigated.The CRI values of Ce:LuAG TC based white LEDs could be increased by a magnitude of 46.2%.Particularly,by combining the as fabricated Ce,Cr:LuAG TCs with a 0.5 at% Ce:YAG TC,surprising CRI values of 88 and 85.5 were obtained in TC based white LEDs and LDs,respectively.Therefore,Ce,Cr:LuAG TC is a highly promising color convertor for high-power white LEDs/LDs applied in general lighting and displaying.

沿黑体辐射线类太阳光LED调光系统调配及优化

为了使发光二极管(LED)光源光谱在可见光波段更接近太阳光光谱,且相关色温实现沿黑体辐射线连续可调,选取不同峰值波长LED芯片及荧光粉,覆盖可见光波段;采用相应LED芯片激发相应荧光粉,获得多个调光光源并记录色点及相对光谱;根据光谱叠加性原理,混合光源色点位于调光光源在CIE 1931色坐标图中围成的区域内。对四色光源混合调光进行了系统的调配优化,基于脉宽调制(PWM)调光模式,使用LED驱动模块控制各调光LED的光通量,实现了光源沿黑体辐射线色温可连续调节。模拟与实测结果显示,在常用照明色温2700~6500 K时,LED光源的一般显色指数大于98,且各特殊显色指数均大于90。光谱特性与太阳光类似,填补了LED白光中青光波段的凹陷,去除了短波长蓝光危害。

激光照明用复合荧光玻璃的制备及性能分析

激光照明以其亮度高、体积小、照射距离远等优势而在汽车照明、军事侦察、投影显示等领域展示出了巨大的发展潜力。然而,荧光玻璃的高显色指数与高光通量之间存在“博弈”关系。基于此,研究制备了一种由黄光荧光粉(YAG:Ce^(3+)和红光荧光粉(CASN:Eu^(2+))组合的复合荧光玻璃。制备的YAG:Ce^(3+)荧光玻璃的内量子效率高达90.50%(为原始荧光粉的95.4%),在150℃时,其发光强度为室温时的93.3%。将YAG:Ce^(3+)的质量百分比为10 wt.%的荧光玻璃与LD封装后,获得的最大光通量为3479.2 lm。7 wt.%CaAlSiN红光玻璃在7.8 W激光激发下的发光通量为413 lm。经优化复合荧光玻璃中黄粉/红粉比例,当10 wt.%YAG:Ce^(3+)与7 wt.%CASN:Eu^(2+)组合时,获得了最高的显色指数82.2,相关色温为4281 K,发光效率为171.2 lm·W^(-1),发光通量为2036.6 lm,实现了荧光玻璃基激光器件的高显色指数和高光通量的发光。因此,同质结构组合的荧光玻璃被视为一种有潜力的荧光转换材料。

2023中国舞台影视灯光调研分析报告——电脑灯篇

本文根据中国照明学会舞台电影电视照明专业委员会2023年调研情况,对电脑灯的新技术、新产品作了介绍,并对电脑灯行业的产品理念、生产工艺、用户需求、技术发展等发展趋势进行分析。

LED混光颜色质量及优化研究

在影视灯光和植物栽培等领域都需要对LED光源进行混光设计。本文采用遗传算法分别针对4色、6色LED混光光谱,单目标优化一般显色指数R_(a)或色彩保真度指数Rf,来获得高一般显色指数R_(a)或者高色彩保真度指数Rf。研究初始种群数目和进化代数对优化数值和优化时长的影响,同时分析一般显色指数R_(a)和色彩保真度指数Rf的关系。采用带精英策略的快速非支配排序遗传算法针对6色LED混光光谱,双目标优化一般显色指数R_(a)和电视光源一致性参数TLCI Q_(a),来同时获得高一般显色指数R_(a)和高电视光源一致性参数TLCI Q_(a),使得该光源能够在一些特定的场景如影视照明等作为良好的照明光源。仿真和实验结果表明:4色混光光源在色温为2700~7500 K范围内,一般显色指数R_(a)都超过95,色彩保真度指数Rf都能够超过93。同时色彩保真度指数Rf对一般显色指数R_(a)具有很好的兼容性。并且随着LED颜色数目的增加,一般显色指数最优化数值在增加。对于双目标优化6色LED混光光谱,在色温为3000~9000 K范围内,都能够保持一般显色指数R_(a)大于96,电视光源一致性参数TLCI Q_(a)大于96。

用于展陈空间的新型LED变色发光凝胶材料及应用效果

为获得更适用于展陈空间的暖白光照明材料,以五水硝酸锆、四(4-羧基苯)乙烯等为原材料,在锆金属有机框架内构建荧光团,制备一种发光凝胶材料,并对其性能和应用效果进行研究。结果表明,与有机配体材料相比,发光凝胶材料的最大吸收峰波长增大,在荧光寿命方面,发光凝胶材料荧光寿命增长到8.12μs,提高幅度为29.92%;发光凝胶材料在50 d去离子水浸泡后基本无Z r离子溶出现象,且浸泡70 d后的光学特性与未浸泡时差别较小,水稳定性较好。以该发光凝胶材料制备LED器件的色温和显色指数分别为3684 K、87.7,流明效率为80.26 Im/W,暖光照明好。

彩超监测胎儿RA血流指标对胎儿宫内窘迫的预测价值探讨

目的探讨彩超监测胎儿RA血流指标对胎儿宫内窘迫的预测价值。方法针对我院自2014年12月~2015年7月检查的60位孕妇出现的胎儿宫内窘迫患者,对其阻力的指数、搏动的指数以及RA血流的指标进行彩色超声监测并其数据资料进行记录、对比分析。结果通过一段时间的彩色超声监测后发现,我院的60位宫内窘迫的胎儿,其阻力的指标、搏动的指标以及RA血流的指标均得到了很好的预测价值。对比前后,P〈0.05。全部宫内窘迫的胎儿患者都得到良好的预测效果。结论彩色超声监测胎儿RA血流指标对胎儿宫内窘迫有非常好的预测价值,有准确、方便等特点。

Luminous efficacy and color rendering index of high power white LEDs packaged by using red phosphor

We packaged a series of high power white LEDs by covering the blue LED chips with yellow phosphor, red phosphor and the two phosphors mixed by appropriate mass ratio, respectively, and discussed the excitation and emission spectrum of yellow phosphor and red phosphor and the characteristics of the LEDs. We found that the luminous efficacy of the white LEDs covered with the two phosphors mixed by appropriate mass ratio was lower than that of the white LEDs covered with yellow phosphor, but the color rendering index was improved observably.

Color-converted remote phosphor prototype of a multiwavelength excitable borosilicate glass for white light-emitting diodes

We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, to 534 nm- peaked green light to emit the desired red light with an excellent transmission in the wavelength range of 400-700 nm which makes this glass suitable for color conversion without a great cost of luminous power loss. In particular, when assembling this glass for commercial white light-emitting diodes, the tested results show that the color rendering index is improved to 84 with a loss of luminous power by 12 percent at average, making this variety of glass promising for inorganic ＂remote-phosphor＂ color conversion.

绿色建筑中导光管采光质量研究

在绿色建筑中采用导光管能提供良好的室内光环境,有利于人们的健康。鉴于以往关于导光管的研究缺乏对采光质量的分析,以两种不同内壁的长径比为2~10的导光管为例,系统地研究了导光管光谱反射率、长径比对透射光显色性和非视觉效应的影响,并与两种常见灯管对比。首先利用TracePro软件和光谱照度计分别获得导光管透射光和灯管的相对光谱,然后计算了光源的一般显色指数(Ra),最后通过Ra数值及相对光谱功率峰值波长位置评价了导光管和灯管的显色性和非视觉效应。结果表明:绿色建筑在选择照明系统时,宜优先选择光谱反射率分布均匀且平均值较大的导光管,同时控制长径比保证优越的采光质量;在条件不允许安装导光管的空间,可选择人工光源替代,同时尽量避免长时间连续使用对人们健康造成损害。

CaTiF_(6)·2H_(2)O:Mn^(4+)窄带红色荧光粉的发光性能及其高显指暖白光LED应用

报道了一种新型的Mn^(4+)掺杂水合六氟钛酸钙CaTiF_(6)·2H_(2)O:Mn^(4+)红色荧光粉,详细研究了基质的结构转变和荧光粉的发光性能及高显色指数(显指)暖白光LED应用。CaTiF_(6)·2H_(2)O:Mn^(4+)在130~200℃间脱水转化为CaTiF_(6):Mn^(4+),荧光光谱发生改变,重新吸附水分子可恢复到CaTiF_(6)·2H_(2)O:Mn^(4+),发光性能不可逆。重要的是,该荧光粉在较长波626 nm和635 nm处分别发射锐线极强的零声子线(ZPL)和ν6振动峰,色坐标为(0.701,0.299),更接近人眼敏感的红光边界650 nm(色坐标x~0.72,y~0.28),有助于提高暖白光LED的显色指数、拓宽背光源的色域。晶体结构和晶体场强度计算指出,Mn^(4+)在CaTiF_(6)·2H_(2)O:Mn^(4+)中占据低对称性的格位,所受到的晶体场强度较弱,Mn—F键的共价性较强。另外,通过表面疏水化显著提升了荧光粉耐湿性能,共掺小离子半径的Si^(4+)增强了荧光粉发光热稳定性。以CaTiF_(6)·2H_(2)O:Mn^(4+)作为红光成分,获得了高显色指数(R_(a)=90,R_(9)=68)的暖白光LED,在高品质的暖白光照明中具有潜在的应用。

基于全蓝光芯片和荧光粉分区涂覆的高显色指数色域可调COB LED光源

针对可调色域技术领域中的传统三基色芯片光源存在的芯片光衰、温度特性不同、光谱不够连续以及五色光源工艺结构复杂等技术痛点,本文基于COB封装,对蓝光LED芯片表面采用荧光粉分区喷涂的方式,设计并制作了一款高显指色域可调的三基色COB LED光源。测试结果表明,通过调节每个区域芯片的驱动电流大小,改变三色光的发光强度能够实现智能调色。在色温为3000~6000 K时,选取的样品光源7个色温下的色坐标有6组位于普朗克曲线上,显色指数最低是72.9、最高为83.4,高于传统RGB芯片光源的34.2和44.5,光谱的连续性也更好,开辟了色域可调的技术创新,能更好地适用于当下对显色指数有着较高要求的商业照明。

2022中国舞台影视灯光调研分析报告——电脑灯篇

本文根据中国照明学会舞台电影电视照明专业委员会2022年调研情况,对电脑灯的新技术、新产品作了介绍,并对电脑灯行业的产品理念、生产工艺、用户需求、技术发展等发展趋势进行分析。