Growth of the green algae Chlamydomonas reinhardtii under red and blue lasers

Red and blue lasers, holding promise as an electric light source for photosynthetic systems on account of being true monochromatic, high-power, and having high electrical-conversion efficiency, were employed in growing a green alga, Chlamydomonas reinhardtii. The laser treatments tested included: 655-nm Red; 680-nm Red; 655-nm Red+474-nm Blue and 680-nm Red+474-nm Blue. A white cold cathode lamp with spectral output similar to that of white fluorescent lamp served as control. C. reinhardtii successfully grew and divided under the 655 and 680-nm red lasers as well as under the white-light control. Supplementing either red with blue laser, however, resulted in increased algae cell count that significantly exceeded those under both red lasers and the white-light control on average by 241%.     

Brightness Perception of Light Source Colors in Dense Fog

The characteristics of our color vision are affected by various visual environments. In this experiment, we examined how colored lights look in dense fog. We used 12 kinds of colored light as a test stimulus. At first, in the absence of fog, subjects matched brightness of all the test stimuli with a reference white light adjusted to 0.1 cd/m² or 0.5 cd/m² in luminance, respectively. They then evaluated the apparent brightness of the test stimuli in dense fog with magnitude estimation of 10 grades. In the presence of fog, test stimuli containing a yellow component were given the highest point value of brightness, while test stimuli containing a blue component were given the lowest point value of brightness in fog. We are confident that in a visual environment involving fog, these results will be extremely helpful and practical.     

Research on phosphor-conversion laser-based white light used as optical source of VLC and illumination

Visible light communication (VLC) based on light emitting diodes (LEDs) or laser diodes (LDs) has attracted considerable interest in recent years. Due to the advantages of laser diodes based on nitrides, such as small size, high brightness, visible light and high bandwidth, it can be applied to illumination and communication at the same time. In this paper, blue laser and yellow phosphors were employed to synthesize white light. And “efficiency droop” is not observed in the LIV characteristics of LD-based white light either. The bandwidth measurement system with high reliability was set up. The bandwidth of blue laser diode and phosphor-conversion laser-based white light was measured. The maximum of optical ?3 dB bandwidth of blue LD is around 1.8 GHz at 80 mA and maximum of optical ?3 dB bandwidth of white light is about 1.3 GHz at 60 mA. The color parameters of the synthetic white light were characterized through integrating sphere. Moreover the trends of test data with injection current were analyzed in detail. The problem of thermal degradation of yellow phosphors has been improved by a special design that can keep a certain distance between the blue laser diode and phosphors. The experiment results verified that laser diodes based on nitrides have promising applications in lighting and communications.     

Effect of nanometer sized Ni dot/Ag/Pt reflection metal of InGaN light emitting diodes on conversion efficiency of yellow phosphor

Nanometer sized Ni-dot/Ag/Pt metal coating films with different Ni-dot sizes were incorporated in InGaN based blue light emitting diodes as p-type reflection metal to enhance the extraction efficiency of blue light. For the reflectivity change from 84% to 93.7%, the optical output power of blue light before phosphor coating and the luminous flux of white light after phosphor deposition have improved by 49.3% and 58.2% at 350 mA, respectively. For the presented white light devices, the blue and yellow luminescence respectively has been improved relatively up to 1.52 and 1.67 times. The improved extraction efficiency of yellow light from the phosphor integrated blue light emitting diode is thought to be attributed to the reduction of round trip loss of blue and yellow light inside the device due to the enhanced reflectivity of nanometer sized Ni/Ag/Pt p-type reflection metal.     

Simple-structure white organic light emitting diodes with high color temperature

We present high color temperature white organic light emitting diodes with a simple p-i-n structure. A sky blue phosphorescent dopant of iridium(III) bis[4,6-(difluorophenyl)-pyridinato-N,C^2’] picolinate and a red phosphorescent dopant of bis(2-phenylquinoline)(acetylacetonate)iridium(III) in the emissive layers is employed to make high color temperature devices. Very stable color variation under ?0.02 until a 5000 cd/m² brightness value is realized by efficient carrier control in a multi stacked emitting layer of blue/red/blue colors. Maximum current and power efficiencies of 23.8 cd/A and 22.9 lm/W in forward direction are obtained. With balanced emissions from the two emitters, the white light emission with very high correlated color temperature of 7308 K as well as CIE coordinates of (0.30, 0.33) is achieved.     

KBaBP2O8:Tm3+: a novel blue-emitting phosphor with high color purity

A series of novel blue emitting K_{1 + x} Ba_{1 ? 2x} Tm _x BP₂O₈ (0.01 ≤ x ≤ 0.08) phosphors were synthesized by a solid-state reaction at a high temperature for the first time. The phase purity and photoluminescence properties were investigated by X-ray diffraction (XRD) and fluorescence spectroscopy (FS) measurements, respectively. The influence of the doping concentration of Tm³⁺ on its relative emission intensity was investigated, and the critical distance was calculated. The as-prepared phosphor can be effectively excited with a 356-nm light, and exhibit blue emission at 457 nm with high color purity. The above work indicates this phosphor could be a potential candidate as blue emitting phosphor for application in white light-emitting diodes.     

A triphenylamine derivative as an efficient organic light color-conversion material for white LEDs

A novel efficient (Φ=0.44) organic yellow-emitting dye, 3-(4-(diphenylamino)phenyl)-1-phenylprop-2-en-1-one (DPPO), was synthesized. The compound was characterized by means of ¹H NMR and differential scanning calorimetry (DSC) and analyzed by quantum chemistry method. It was found that DPPO could be effectively excited by the InGaN-based blue LED. Photo-durability data of DPPO were studied. Bright white light of Commission International del’ Eclairage (CIE) x=0.30, y=0.33 was obtained by using DPPO as a light color-conversion material (CCM).     

顶发射白光OLED微型显示器的蓝光掺杂特性研究

白光OLED微型显示器在信息显示领域具有重要的应用。采用真空镀膜系统,依次蒸镀Ag/ITO复合薄膜作为阳极结构,共蒸制备Mg∶Ag复合膜作为半透明阴极结构,NPB作为空穴传输材料和黄光主体材料,rubrene作为黄光掺杂料,AND作为蓝光主体料,DSA-Ph作为蓝光掺杂料,Alq3作为电子传输材料,以结构和工艺简化的蓝、黄光互补色来实现白光,通过共蒸发形式制备了结构为Ag/ITO/NPB/NPB∶rubrene（1.5%）/ADN∶DSA-Ph（x%/x=2,5,8）/Alq3/Mg∶Ag的白光OLED微型显示器,利用由Photo Research PR655光谱仪、Keithley 2400程控电源组成的光谱测试系统对器件的光电性能进行表征,研究了蓝光掺杂比对白光OLED微型显器性能的影响。结果表明,随着蓝光掺杂比的增加,白光OLED微型显示器的亮度先增加后降低,蓝光、黄光峰位有所偏移,色坐标发生一定的漂移,蓝光色纯度增加,可通过调控发光材料掺杂比实现白光OLED微型显示器性能的可控制备。初步优化获得的蓝、黄混合白光OLED微型显示器的器件,当驱动电压为5.0 V时,器件亮度达到3 679 cd·m-2,CIE坐标为（0.263,0.355）。     

无封胶白光数码管荧光粉转换率的分析

研究无封胶白光数码管衰减机理,利用蓝白比拟法测算无封胶白光数码管荧光粉转换率.对蓝白数码管分3组进行电流老化实验,老化电流分别为20、40mA和60mA.在恒定直流为20mA,老化时间为1000h实验中,通过分析蓝、白数码管光谱曲线的变化,研究了蓝光光输出功率和黄光光输出功率衰减情况,利用实验数据,分析表明了荧光粉转换率的衰减是影响无封胶白光数码管老化的重要因素.同时分析比较了在40mA和60mA不同电流老化实验下得到的荧光粉转换率,发现工作电流越大,荧光粉转化率衰减越快,符合无封胶白光数码管在大电流作用下衰减更快的实际情况,影响使用寿命.对荧光粉转换率的研究将为无封胶白光数码管的应用及进一步研究无封胶白光数码管衰减原因提供参考.     

n型掺杂层结构对n-i-p型微晶硅电池性能和光致衰退特性的影响

采用射频化学气相沉积法,制备了一系列具有不同晶化率n型掺杂层的n-i-p结构微晶硅薄膜太阳电池.发现本征层的结构很大程度上依赖于n型掺杂层的结构,特别是n/i界面处的孵化层厚度以及本征层的晶化率.该系列太阳电池在100 mW/cm²的白光下照射400 h,实验结果证实了本征层晶化率最大（X_c(i)=65%）的电池性能表现出最低的光致衰退率.拥有非晶/微晶过渡区n型掺杂层的电池（本征层晶化率X_c(i)=54%）分别 关键词： 微晶硅 n-i-p结构太阳电池 光致衰退 晶化率     

不同LED光质对人参种苗叶片生理特性和超微结构的影响

主要针对不同光质对人参种苗叶片生长影响的研究,从而探究人参工厂化育苗的优良光质,为提高种苗质量提供基础依据。试验设置六组处理,分别为白光（W,作为对照）、蓝光（B,450～470 nm）、红光（R,625～655 nm） 、绿光(G, 510～530 nm)、黄光(Y, 585～605 nm)、红蓝光(RB, R/B=4∶1),白光作为对照光源。试验结果表明,不同光质下生长的人参种苗叶片在外观形态、生理特性和细胞结构上都显现明显的差异。在叶面积的生长过程中,红蓝光和白光下的叶面积较大,红光次之,蓝光下最小;在叶绿素含量的分布中,添加蓝光的处理组明显高于对照组,说明蓝光对叶绿素的合成有关键作用,红光下叶绿素含量最低,表明红光不利于叶绿素的合成。蓝光、黄光和白光下叶绿素荧光电子效率较高,而在气孔特性上,绿光、红光和白光的气孔数量较多,单个气孔面积蓝光和红蓝光下较大。通过电镜下叶片超微结构的观察发现,不同光质对叶片的细胞结构产生了明显的影响,主要表现在线粒体和叶绿体的分布以及叶绿体的结构上,其中白光和蓝光照射下的线粒体和叶绿体数量较多,叶绿体片层结构垛叠数上也更紧凑丰富。另外,不同光质下生长的幼苗叶片衰老进程也产生了明显的差异,蓝光、红蓝光照射下衰老速度较快。综上所述,不同光质对于人参种苗叶片生长的影响各不相同,蓝光和红蓝复合光照射具有较多的优良性状和较好的生理参数,因此在应用和实践上还需要根据具体的需求制定相应的光质配比策略,以达到壮苗丰产的目的。     

白光LED用稀土荧光粉的制备和性质

在还原气氛保护下利用高温固相法合成了化学组分为(M₁,M₂)₁₀(PO₄)₆X₂(M₁=Ca,Sr,Ba;M₂=Eu,Mn;X=F,Cl,Br)的可被紫光激发的蓝光、绿光和红光荧光粉,制备了紫光LED芯片+蓝光荧光粉+YAG荧光粉的二基色白光LED;紫光LED芯片+蓝光荧光粉+红光荧光粉的二基色白光LED,以及紫光LED芯片+蓝光荧光粉+绿光荧光粉+红光荧光粉的三基色白光LED。测试了所有制备的白光LED在不同的直流电驱动下的色度坐标、相关色温和显色指数。     

Cold white light generation through the simultaneous emission from Ce3+, Dy3+ and Mn2+ in 90Al2O3·2CeCl3·3DyCl3·5MnCl2 thin film

The photoluminescence of a CeCl₃, DyCl₃ and MnCl₂ doped aluminum oxide film deposited by ultrasonic spray pyrolysis was characterized by excitation, emission and decay time spectroscopy. A nonradiative energy transfer from Ce³⁺ to Dy³⁺ and Mn²⁺ is observed upon UV excitation at 278 nm (peak emission wavelength of AlGaN-based LEDs). Such energy transfer leads to a simultaneous emission of these ions in the blue, green, yellow and red regions, resulting in white light emission with CIE1931 chromaticity coordinates, x=0.34 and y=0.23, which correspond to cold white light with a color temperature of 4900 K.     

光照强度对蛇足石杉共生蓝藻细胞悬浮培养的影响

以蛇足石杉孢子囊为材料,分离出蛇足石杉共生蓝藻细胞,研究光照强度对液体培养的共生蓝藻细胞生长的影响.研究结果表明,在光强500 Lx下,共生蓝藻的生长速率最大;增加光照强度(> 2000 Lx)将抑制共生蓝藻的生长,菌体褪绿变白;在共生蓝藻生长过程中,蓝藻细胞内叶绿素a的含量随着光强的增加而显著减少,这与其在强光照下生物量的降低呈正相关.不同光质实验结果表明,绿光和蓝光条件下蛇足石杉内生藻生长快而红光条件下藻体增殖最慢,这与在绿光和蓝光条件下藻体细胞合成的色素含量增高有密切的关系.实验结论:蛇足石杉共生蓝藻细胞适宜的光照条件是弱光光照,适宜的光质是绿光或蓝光.     

白光LED极限流明效率的计算

对蓝光芯片加黄色荧光粉制备白光LED方法的流明效率进行了理论计算。根据光度学原理,我们考虑到视觉函数V(λ)的修正,以色坐标为x=0.325,y=0.332,显色指数为81.5,色温为5 914 K的白光LED发光光谱为依据,计算了白光LED流明效率的理论极限:得出每瓦白光LED辐射光功率产生的光通量为298.7 lm,白光LED发射的总光子数为2.7×10¹⁸。在理想情况下,注入一个电子-孔穴对产生一个蓝光光子,设荧光粉的量子效率为1,因此,注入的电子-孔穴对数亦等于白光光子数,进而计算出白光LED每辐射1 W的光功率所需的电功率为1.51 W,上述白光LED发光光谱对应的白光LED的电-光转换的理论极限流明效率为197.8 lm/W。     

Tunable electroluminescence from n-ZnCdO/p-GaN heterojunction

By cadmium allowing of zinc oxide, a phosphor-free single-chip white light emission diode based on n-ZnCdO/p-GaN heterostructure has been realized. The white light electroluminescence was produced by the superposition of two intense emission bands, a blue band and a yellow band. The origins of the blue band was contributed by both GaN and ZnCdO, while the yellow band was from the recombination of the holes and the electrons in the interface of GaN and ZnCdO.     

功率型白光LED光学特性退化分析

将GaN基蓝光芯片涂敷YAG荧光粉和透明硅胶制成额定功率为1 W的白光发光二极管(LED),对其施加900mA的电流应力,在老化过程中测量白光LED的主要光学参数,考察其光学特性的退化情况。经过4 200 h的老化,样品光通量退化为初始值的15%~18% 。样品的漏电流明显增大,表明芯片有源区缺陷密度提高,但光谱分布图中蓝光部分的辐射量未减少,仅观察到黄光部分辐射量的减少,推断出YAG荧光粉的转换效率降低。同时,从原理上分析了样品色温逐渐增大,显色指数基本不变的原因,对大功率白光LED在照明领域的应用有一定的借鉴意义。     

Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.     

LED激发有机材料MPPV的光谱分析

通过旋涂方法在玻璃片上涂敷一层有机材料MPPV,其中有机材料MPPV溶于有机溶剂四氢呋喃溶液中,MPPV:四氢呋喃的比例分别为25mg∶1mL,50mg∶1mL,100mg∶1mL,150mg∶1mL。然后分别使用蓝光、白光LED去照射有机薄膜层来研究其发光特性。结果表明:蓝光LED、白光LED均能激发有机材料MPPV使其在600～750nm区域产生红光光谱,且随着溶解质量分数的增加,光谱色坐标从(0.265 4,0.248 9)移向(0.395 4,0.288 0),发生红移。当MPPV:四氢呋喃的比例为100mg∶1mL时,拥有最好的显色指数86.1,实验中色温最低可达2 609K,这比使用蓝光LED激发黄色YAG荧光粉得到的白光LED色温更低。因此蓝光LED、白光LED通过激发有机材料MPPV可以显著提高LED的显色指数及发光性能。     

Analysis on the high luminous flux white light from GaN-based laser diode

We fabricated a phosphor-conversion white light using an InGaN laser diode that emits 445 nm and phosphor that emits in the yellow region when excited by the blue laser light. At 500 mA injection current the luminous flux and the luminous efficacy were 113 lm and 44 lm/W, respectively. The relationship of the luminous flux and the luminous efficacy of the white light with an injection current were discussed. Based on the evaluation method for luminous efficacy of light sources established by the Commission International de I’Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the experiment results and the maximum luminous efficacy of this white light fabrication method were also presented.