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.

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.

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.

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.

显色指数CQS和CRI对光源显色性评价的差异分析

由于现行显色指数CRI(Color Rendering Index)在评价白光LED光源时出现越来越多的问题,而较为权威的新指标CQS(Color Quality Scale)并未得到广泛的认可,本文采用大量典型光源实例,论证CQS与CRI的一致性和差异性。本文收集市面上常见的10种荧光灯、7种RGB LED和25种Phosphor white LED灯,分别计算了两种显色性评价指数CRI R_a和CQS Q_a,并分别对不同类型的光源进行相关性分析、色差分析及差值分析。结果发现:①对荧光灯的显色性评价,CQS与CRI基本一致,但对色温极低以及对高饱和度色块显色差的灯有做一些修正;②对Phosphor white LED灯的显色性评价,CQS与CRI基本一致,但对RGB LED的显色性评价,CQS做了修正,与CRI相差较大;③通过差值分析法,可以看到CQS Q_a和CRI R_a差值比例的整体趋势随着CRI R_a增大而减小,当CRI R_a达到90的时候,两者的差值比例接近为0。

CRI 2012及其对光源显色性评价的实践意义

介绍了2013年K.A.G.Smet等人为替代现行显色指数CRI提出的最新显色性评价指标CRI 2012的制定背景、计算方法和主要结论。通过对26种LED和17种荧光灯的光谱进行测量和计算,分析了CRI 2012对不同类别光源显色性评价的指导意义。

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.

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.

解析显色指数CRI

详细解释"显色指数"的含义与测算方法,阐述"显色指数"对于评价光源性能的重要意义。

Self-Power Consumption Research with the Thermal Effects and Optical Properties of the HCRI-BIPV Window System

The building integrated photovoltaics （BIPV） application is one of the main study topics in the sustainable building field. In this paper, the high color rendering index （HCRI）-BIPV window system is developed to be used in the indoor environmental control, whose module material has appeared to be effective in improving the visible transmittance and reducing the absorption. This paper describes the performance of grid-connected HCRI-BIPV window system with 0.75 kWp capacity installed in an office building for a natural ventilation solution. The experimental results indicate that accumulative power generation of the HCRI-BIPV window system is 157.60 WKh during the 7-month experiment period. For consideration of each evaluated factors, the HCRI-BIPV window system not only offers the passive energy situation for its power loading but also improves the indoor thermal environment by natural ventilation.

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.

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。

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。

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。

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。

不同光源的显色性比较实验研究

本文对白炽灯、荧光灯、白光LED球形灯等六种不同电光源的显色性进行了实验研究,包括显色指数的测量及显色能力的主观评价。结果表明,白炽灯、荧光灯的显色指数测试结果与显色能力主观评价结果相吻合,但白光LED球泡灯的显色指数测试结果与显色能力主观评价有一定出入。文章最后对评价LED显色性时需注意的问题提出了几点建议。