高效氟磷酸盐玻璃白光荧光体制备及发光特性

采用熔融淬火方法制备了一系列Sn2+，Dy3+单掺及Sn2+-Dy3+共掺氟磷酸盐玻璃荧光体。利用紫外-可见分光光度计分别对各玻璃荧光体的透过光谱、激发光谱、发射光谱及荧光寿命等进行了测试和分析。结果发现在紫外光激发下，对于Sn2+、Dy3+单掺氟磷酸盐玻璃可分别获得高效的蓝光与黄光发射，且Sn2+单掺氟磷酸盐玻璃荧光体发光显色指数和量子效率最高；对于Sn2+-Dy3+共掺氟磷酸盐玻璃荧光体可实现高效的白光发射，且发现在Sn2+和Dy3+之间存在明显的能量传递，通过调节Dy3+掺杂浓度，两离子之间的能量转移效率亦随之改变，从而可对其白光色度进行调节。当Dy3+掺杂浓度为3 Wt%时，利用280 nm商用LED芯片激发可获得对应色坐标为(0.311，0.330)，量子效率为56.3%，亮度为6 706 cd·m-2的近纯白光发射。此外，对各类玻璃样品的DSC、导热及其他光学性能也进行了测试与计算，获得了各样品的热导率、量子效率、色坐标、显色指数等参数。研究结果表明，制备的高效氟磷酸盐玻璃完全有望作为可调谐白光发光荧光体应用于商用LED。     

2, 6-双(2-苯并咪唑)吡啶-乙酸锌的合成和光谱性能

合成了一种新型的蓝光发射材料2,6-双(2-苯并咪唑)吡啶-乙酸锌,并利用元素分析、红外光谱、UV-Vis吸收谱、荧光激发光谱和荧光发射光谱研究了其结构、光学特性、能级结构和发光机理。结果表明,2,6-双(2-苯并咪唑)吡啶-乙酸锌是一种三齿配体的发光材料。在N,N-二甲基甲酰胺(DMF)溶液体系中测定了材料的紫外吸收光谱,2,6-双(2-苯并咪唑)吡啶的吸收峰波长主要为330,344nm;2,6-双(2-苯并咪唑)吡啶-乙酸锌的吸收峰波长主要为346,366nm。禁带宽度为3.01eV,在紫外光激发下,在DMF溶液体系中的荧光发射峰在458nm处,固态荧光发射峰在475nm,均为蓝色荧光,色纯度高,荧光量子效率高,其荧光发射主要来源于长波吸收带,最大波长吸收带对荧光发射贡献最大。有望通过合理的设计运用到有机电致发光器件中去。     

Carbon dioxide adsorption studies on delafossite CuFeO2 hydrothermally synthesized

Delafossite CuFeO₂ oxide was synthesized by a hydrothermal technique using Cu₂O and FeOOH as precursors with the addition of fused NaOH as mineralizer. The amount of rhombohedral and hexagonal delafossite phase formed depends on the synthesis time lapses between 2 and 5 days and on the NaOH concentration. The compounds obtained were analyzed with Raman Spectroscopy, X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) in order to obtain their morphological and structural properties. Optical behavior was studied by UV–vis Spectroscopy and gas adsorption measured with a Quartz-Crystal Microbalance (QCM). Our results show that this type of hydrothermal synthesis is capable of recreating the delafossite-type structure of copper-iron oxide and produces a high yield of material with the right stoichiometry. The highest uptake of carbon dioxide is observed on the sample with the highest ratio between rhombohedral and hexagonal delafossite phase.     

Eu3+掺杂CaWO4红色荧光粉发光性质的浓度依赖关系研究

采用共沉淀法制备了不同Eu³⁺掺杂浓度的CaWO₄荧光粉材料.通过X射线衍射和场发射扫描电镜技术对样品的结构和形貌进行了表征.测量了各样品的激发光谱、发射光谱和荧光衰减曲线, 计算了各样品的部分Judd-Oflet (J-O)参数和^5D_0 (Eu³⁺)能级量子效率,以及荧光粉的色坐标, 讨论了样品电荷迁移带相对强度、J-O参数、量子效率与掺杂浓度的依赖关系.对Eu³⁺掺杂的CaWO₄ 发光材料的光致发光性质的研究表明,在CaWO₄: Eu³⁺中⁵D₀→⁷F₂跃迁的616~nm 红色发光能被394.5~nm和465~nm的激发光有效激发,具有近紫外(或蓝光)激发效率高和猝灭浓度大的优点, 有潜力成为高效的近紫外(或蓝光)激发白光发光二极管用红色荧光粉材料.     

广色域钙钛矿量子点/荧光粉转换白光LED

报道了一种使用绿色CsPb（Br_0.75I_0.25）₃无机钙钛矿量子点（PeQDs）和红色K₂SiF₆：Mn⁴⁺（KSF）荧光粉作为荧光转换材料实现广色域白光LED的方法。合成了绿色CsPb（Br_0.75I_0.25）₃量子点,峰值波长为526 nm,半高宽度为27 nm,具有很好的单色性。采用蓝光LED芯片、红色KSF荧光粉和绿色CsPb（Br_0.75I_0.25）₃ PeQDs组合能够覆盖CIE 1931颜色空间中很广的色域,达到NTSC标准色域的107%。利用丝网印刷和紫外固化工艺制作了PeQDs薄膜、KSF薄膜和PeQDs-KSF混合薄膜,与蓝光LED芯片组合得到了3种不同封装形式的白光LED器件。研究了不同封装形式对器件光学特性的影响,KSF薄膜在外侧的样品光效最高,为102 lm/W,色温为7 100 K。     

Photo-physical and lasing characterisation of a polyparaphenylenevinylene (PPV) neat film

The wave-guided travelling-wave laser action (amplified spontaneous emission) of a neat film of poly(p-phenylenevinylene) (PPV) on a quartz glass substrate prepared by a sulfinyl precursor technique is studied. The samples are transversally pumped with picosecond excitation pulses (wavelength 347.15 nm, duration 35 ps). Lasing occurs at 550 nm. The optical constants of the neat films are determined by transmittance measurements exploiting the multiple beam interference in the transparency region. A fluorescence spectroscopic characterisation is carried out determining the fluorescence quantum distribution, fluorescence quantum yield, degree of fluorescence polarisation, and fluorescence lifetime. The emitting chromophore size (emitting singlet exciton extension) is determined by the ratio of exciton radiative lifetime to repeat-unit based radiative lifetime. The obtained size of about two repeat units is discussed in a disordered solid-state polymer model.     

Detection and Evaluation of Normal and Malignant Cells Using Laser-Induced Fluorescence Spectroscopy

The aim of this research is to study the normalized fluorescence spectra (intensity variations and area under the fluorescence signal), relative quantum yield, extinction coefficient and intracellular properties of normal and malignant human bone cells. Using Laser-Induced Fluorescence Spectroscopy (LIFS) upon excitation of 405 nm, the comparison of emission spectra of bone cells revealed that fluorescence intensity and the area under the spectra of malignant bone cells was less than that of normal. In addition, the area ratio and shape factor were changed. We obtained two emission bands in spectra of normal cells centered at about 486 and 575 nm and for malignant cells about 482 and 586 nm respectively, which are most likely attributed to NADH and riboflavins. Using fluorescein sodium emission spectrum, the relative quantum yield of bone cells is numerically determined.     

紫色发光二极管激发下钐掺杂的重金属硅酸盐玻璃的辐射通量与光通量(英文)

采用积分球测试系统配以内芯直径为400μm的功率光纤连接的CCD探测器,在紫色发光二极管的激发下,对Sm3+掺杂的重金属硅酸盐(CAS)玻璃的荧光光谱进行了表征,实现了以荧光发射特性绝对评价为目的绝对光谱功率分布测定,进一步求得了辐射通量,光通量等荧光特征参数。测试与计算结果表明,在整个可见光谱区域,总的辐射通量和光通量分别为712μW和12.1 mlm,其中Sm3+的4个特征发射峰的辐射通量和光通量分别为36μW和9.7 mlm,占可见区总量的5%和80%,其可见特征发射的总量子产率为2.3%。Sm3+掺杂CAS玻璃可见区多通道辐射跃迁的绝对光谱参数评估为照明和显示器件的研发提供了有益的参考依据。     

A highly efficient white-light-emitting diode based on a two-component polyfluorene/quantum dot composite

Organic light-emitting diodes (OLEDs) are attracting great interest of the scientific community and industry because they can be grown on flexible substrates using relatively simple and inexpensive technologies (solution processes). However, a problem in the fabrication of white OLEDs is that it is difficult to achieve a balance between the intensities of individual emission components in the blue, green, and red spectral regions. In this work, we try to solve this problem by creating a two-component light-emitting diode based on modified polyfluorene (PF-BT), which efficiently emits in the blue–green region, and CdSe/ZnS/CdS/ZnS semiconductor quantum dots emitting in the orange–red region with a fluorescence quantum yield exceeding 90%. By changing the mass ratio of components in the active light-emitting composite within 40–50%, it is possible to transform the diode emission spectrum from cold to warm white light without loss of the diode efficiency. It is very likely that optimization of the morphology of multilayer light-emitting diodes will lead to further improvement of their characteristics.     

Al18B4O33：Cr3+荧光粉的制备及发光性质研究

采用高温固相法合成了Al₁₈B₄O₃₃：Cr³⁺荧光粉,使用X射线粉末衍射仪和FSEM对样品的结构和形貌进行了表征,采用荧光分光光度计及紫外分光光度计研究了样品的发光性质及光吸收性质。结果表明,在紫外光或530~630 nm可见光激发下,样品能够发射出660~720 nm的红光,两个发射峰分别位于683 nm和694 nm,其最佳激发波长为590 nm。当原料中Al和B的量比为3.5时,样品的发光最强。初步分析了H₃BO₃的加入对样品发光影响的机理。样品的最佳煅烧温度为1 150 ℃。随着Cr³⁺掺杂浓度的升高,样品发光增强,但发光效率降低。样品的漫反射光谱表明,样品对绿光、黄橙光及紫外光有较强的吸收,是一种潜在的优良农用转光剂材料。     

Assembly‐Induced Emission of Cellulose Nanocrystals for Hiding Information

Fluorescent‐labeled cellulose nanocrystal (CNC) films have been used to record and protect information in paper materials, whereas the fluorescent materials usually suffer photobleaching. Herein, a strategy of solid‐state emission induced by the vertical assembly of CNCs was established. The assembly‐induced emission starts from the structural diffraction of CNC, whose wavelength is adjusted into the ultraviolet (UV) region for hiding information under natural light. The small diameter (≈10 nm) of CNCs then promotes the resonance between the vertically assembled CNCs and the UV light, leading to a strong blue emission with an emitting quantum efficiency as high as 13.90%. By introducing the vertical‐assembly film with a specific pattern into paper materials, an anti‐counterfeiting image is obtained under a UV radiation. Since CNCs are a kind of cellulose with high crystallinity, this material can be a wear‐resistant anti‐counterfeiting material for banknotes or other paper applications.     

激光激励下镝离子掺杂氟硼酸盐玻璃荧光体的辐照参数

采用高温熔融法制备了镝离子掺杂氟硼酸盐玻璃荧光体,利用积分球绝对光谱测试系统,在453 nm蓝色激光二极管激发下,对玻璃荧光体的荧光光谱进行表征,解析出玻璃荧光体的相关绝对荧光参量。测试与计算结果表明,1.0 Wt% Dy₂O₃掺杂玻璃荧光体在功率15.81 mW的蓝色激光激发下,净发射光谱功率是286.91 μW,发射光子数为17.17×1014 cps,其荧光量子产率达到25.86%。为提高玻璃荧光体对泵浦激光的利用率,减少残余激光成分,进而改善组合光品质,制备了大体积的1.5 Wt% Dy₂O₃掺杂玻璃荧光体,在高功率的蓝色激光激发下获得白色照明效果,该玻璃荧光体在激发功率分别为56.0和252.7 mW的激光激发下,组合荧光对应的色坐标分别是(0.316, 0.287)和(0.303,0.268)。激光激励下的高效白色发光表明Dy3+掺杂氟硼酸盐玻璃荧光体在激光照明领域具有良好的应用前景。     

有机电致发光白光器件的研究进展

在十多年的时间里,有机电致发光二极管(Organic Lightemitting Diodes,OLEDs)的研究和应用取得了长足的进展。有机电致发光器件具有许多优点,例如:自发光、视角宽、响应快、发光效率高、温度适应性好、生产工艺简单、驱动电压低、能耗低、成本低等,因此有机电致发光器件极有可能成为下一代的平板显示终端。有机电致发光白光器件因为可以用于全彩色显示和照明,已成为OLED研究中的热点。介绍了有机电致发光白光器件的研究进展,按发光的性质将白光器件分为荧光器件和磷光器件两类,按发光层数将白光器件分为单层和多层器件,对相关材料、器件结构、发光机理等方面进行了讨论。     

Chromaticity-tunable white light emission from organic multiple-quantum-well structure

Organic multiple quantum wells (MQWs) white light emitting devices are fabricated in which blue fluorescent dye, a trimer of N-anylbenzimidazole (TPBI) and orange fluorescent rubrene doped tris (8-hydroxyquinoline) Aluminum act as quantum-well light emitting layers between triphenyldiamine derivative (TPD) potential barrier layers, and aluminium complex (Alq) act as an electron transporter and green emitter. The injected carriers are confined in different quantum wells and Alq layer. The white light emission comes from a combination of photons generated in different light emitting layers. The Commission Internationale de l' Eclairage (CIE) coordinates of the emitted light are tuned by increasing the number of TPBI wells due to its low fluorescent efficiency compared with rubrene.     

Pure blue and white light electroluminescence in a multilayer organic light-emitting diode using a new blue emitter

We characterized the 6,12-bis{[N-（3,4-dimethylphenyl）-N-（2,4,5-trimethylphenyl）]amino} chrysene （BmPAC）, which has been proven to be a blue fluorescent emission with high EL efficiency. The blue fluorescent device exhibits good performance with an external quantum efficiency of 5.8% and current efficiency of 8.9 cd/A, respectively. Using BmPAC, we also demonstrate a hybrid phosphorescence/fluorescence white organic light-emitting device （WOLED） with high efficiency of 36.3 cd/A. In order to improve the relative intensity of blue light, we plus a blue light-emitting layer （BEML） in front of the orange light emitting layer （YEML） to take advantage of the excess singlet excitons. With the new emitting layer of BEML/YEML/BEML, we demonstrate the fluorescence/phosphorescence/fluorescence WOLED exhibits good performance with a current efficiency of 47 cd/A and an enhanced relative intensity of blue light.     

UV exposure and photon degradation of Alq3 powders

Tris-(8-hydroxyquinoline)aluminum (Alq₃) is a widely used light emitting material. It is also used as an electron transporting layer in organic light emitting devices (OLEDs). Degradation is, however, a major problem in these devices. The device performance is affected by parameters such as air, moisture and light exposure [1,2]. In this work the effect of photon degradation of Alq₃ in air is investigated. Alq₃ phosphor powder was synthesized using a co-precipitation method and recrystalized in acetone. The structure of the sample was determined by using x-ray diffraction (XRD). The averaging particle size estimated from the broadened XRD peaks using Scherrer's equation was 40±4 nm in diameter. The excitation photoluminescence data that was collected correspond well to the absorption data. To study the photon degradation, the sample was irradiated with an UV lamp for ∼330h. The emission data was collected and the change in photoluminescence intensity with time was monitored.     

硅基发光材料研究进展

微电子技术是高技术中的关键技术，硅是微电子技术的基础材料，但是硅是一种非发光材料，为了发展光电集成技术，必须大力发展硅基发光材料，多孔硅是一种有希望的硅基发光材料，它表明纳米晶粒中的量子限制效应对光发射是极有效的，随之涌现出一系列量子限制硅基发光材料，为发展光电子集成提供了新的途径。     

大气环境下合成白光发射的Tb3+/Eu3+共掺杂全无机卤化物钙钛矿量子点

为克服因混合不同卤化物钙钛矿量子点发生阴离子交换反应、不稳定的红光发射卤化物钙钛矿量子点等而导致在获取白光发射方面存在的不足,提出了一种可以在大气环境下合成Tb³⁺,Eu³⁺稀土离子共掺杂全无机卤化物钙钛矿量子点的方法。调节Tb³⁺,Eu³⁺稀土离子的掺杂比例,调控从钙钛矿量子点主晶格到Tb³⁺和Eu³⁺离子的能量转移,获得了单一组分、白光发射的钙钛矿量子点(Tb,Eu):CsPbCl3和(Tb,Eu):CsPb(Cl/Br)3,并对量子点的形貌、结构、发光性能及能量传递机理和稳定性进行了详细研究。研究结果表明:在365nm激光激发下,不同含量Tb³⁺/Eu³⁺离子共掺杂的钙钛矿量子点(Tb,Eu):CsPbCl3发射光谱对应的色坐标位于1931色度图中的白光区域。在进料比PbCl2∶TbCl3∶EuCl3为1∶1.5∶1时,量子产率为3.59%,比纯的CsPbCl3量子点的量子产率(0.57%)提高了6倍。进一步研究发现,该(Tb,Eu):CsPbCl3量子点在空气中储存2个月之后,量子产率几乎保持不变(3.63%),保持了良好的稳定性。此外,研究了采用不同溶剂(正辛烷、十八烯)合成Tb³⁺/Eu³⁺共掺杂钙钛矿量子点的发光特性。Tb³⁺/Eu³⁺离子共掺杂的钙钛矿量子点(Tb,Eu):CsPbCl3可实现单一组分的白光发射,有良好的稳定性,具备一定的应用前景。     

白光LED用红色发射荧光粉YVO_4:Ce~(3+)(Gd~(3+))的制备与表征

用高温固相反应法制备了稀土离子Ce3+、Gd3+双掺杂的YVO4发光材料,通过X射线衍射(XRD)、扫描电镜(SEM)、激发以及发射光谱等测试手段对YVO4:Ce3+(Gd3+)荧光粉的制备条件、发光性能以及表面形貌进行了研究。XRD结果表明,在1100℃恒温5 h可得到Ce3+(Gd3+):YVO4纯相。SEM结果显示颗粒基本为球形,粒径约为300~500 nm。激发光谱测试表明,Ce3+(Gd3+):YVO4荧光粉在近紫外光区(232 nm)和蓝光区(424 nm)可以被有效地激发,用424 nm的蓝光激发样品时,Ce3+(Gd3+):YVO4荧光粉在611 nm和659 nm处的发光强度最大;因此,这种荧光粉可以作为组合型白光LED的红色发射荧光粉的候选材料。     

Optimization of a GaN-based irregular multiple quantum well structure for a dichromatic white LED

GaN-based irregular multiple quantum well(IMQW) structures assembled two different types of QWs emitting complementary wavelengths for dichromatic white light-emitting diodes(LEDs) are optimized in order to obtain near white light emissions.The hole distributions and spontaneous emission spectra of the IMQW structures are analysed in detail by fully considering the effects of strain,well-coupling,valence band-mixing and polarization effect through employing a newly developed theoretical model from the k · p theory.Several structure parameters such as well material component,well width,layout of the wells and the thickness of barrier between different types of QWs are employed to analyse how these parameters together with the polarization effect influence the electronic and the optical properties of IMQW structure.Numerical results show that uniform hole distributions in different types of QWs are obtained when the number of the QWs emitting blue light is two,the number of the QWs emitting yellow light is one and the barrier between different types of QWs is 8nm in thickness.The near white light emission is realized using GaN-based IMQW structure with appropriate design parameters and injection level.