New poly(p‐phenylene vinylene) derivatives with two oxadiazole rings per repeat unit: Synthesis,photophysical properties,electroluminescence, and metal ion recognition

Two new poly(p‐phenylene vinylene) derivatives OX1‐PPV and OX2‐PPV bearing two 1,3,4‐oxadiazole rings per repeat unit and a fully conjugated backbone with solubilizing dodecyloxy side groups were synthesized and investigated. The amorphous conjugated polymers had glass‐transition temperature values of 60–75 °C and emitted intense blue or greenish‐blue light in solution with photoluminescence (PL) emission maxima at 379–492 nm and PL quantum yields of 0.41–0.52. In the solid state they emitted yellowish‐green light with PL emission maxima at 533–555 nm. Cyclic voltammetry showed that both conjugated polymers had reversible reduction and irreversible oxidation, making them n‐type materials. The electron affinity of OX2‐PPV was estimated as 2.85 eV whereas that of OX1‐PPV was 2.75 eV. Yellow electroluminescence (EL) was achieved from single‐layer light‐emitting diodes of OX2‐PPV with an EL emission maximum at 555 nm and a brightness of 70 cd/m². Polymer OX2‐PPV, which was functionalized with 2,6‐bis(1,3,4‐oxadiazole‐2‐yl)pyridine, demonstrated sensitivity to various metal ions as a fluorescence‐mode chemosensor. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2112–2123, 2004     

LED铁路旅客引导系统的分析与设计

LED旅客引导系统,采用一台微机控制多台单片机的类网络控制结构,具有灵活的控制方式;采用LED显示,满足了显示的直观性、美观性、灵活性及耐久性。控制软件还提供了良好的用户界面,使得操作人员操作简单、灵活,便于掌握.     

白光发光二极管的制备技术及主要特性

利用发射波长为470nm的蓝光发光二极管作为基础光源，通过荧光粉转换方法制备白光发光二极管，荧光粉主要采用稀土激活的铝酸盐Y3Al5Ol2：Ce3 (YAG)。在工作电流为15mA条件下，所研制的白光LED的法向光强为2890mcd；色坐标为x=0.29，y=0．33；显色指数为77；流明效率为14．9lm／w。研究制备了不同色温的白光LED，色温范围从2700～8000K，研究了色温与色坐标之间的对应关系。并且与国外同类产品进行比较。部分指标已经超过了国外同类产品水平。     

Optical and electrochemical properties of copoly(aryl ether)s consisting of alternate 2,5‐distyrylbenzene and electron‐transporting oxadiazole or triazole derivatives

New copoly(aryl ether) P1 consisting of alternate electron‐transporting 2‐(3‐(trifluoromethyl)phenyl)‐5‐(4‐(5‐(3‐(trifluoromethyl)phenyl)‐1,3,4‐oxadiazol‐2‐yl)‐2,5‐bis(hexyloxy)phenyl)‐1,3,4‐oxadiazole and hole‐transporting 2,5‐distyrylbenzene (DSB) was synthesized via nucleophilic substitution polymerization. We investigated the optical and electrochemical properties of alternate copoly(aryl ether)s P1 – P6 , which contain the same hole‐transporting DSB segments, but with different electron transporting segments. The effect of trifluoromethyl groups in electron transporting segments is also discussed. Referencing to the spectra of their model compounds M1 – M4 , the emissions of P1 – P3 are dominated exclusively by the hole‐transporting fluorophores with longer emissive wavelength about 452–453 nm via efficient excitation energy transfer. Furthermore, P1 – P3 also exhibit unique variations in energy transfer in acidic media and solvatochromism in organic solvents. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P1 – P4 , estimated from electrochemical data, are ?5.12, ?5.15, ?5.18, ?5.00 eV and ?2.93, ?3.39, ?3.49, ?2.76 eV, respectively. The electron and hole affinity of P1 – P6 can be enhanced simultaneously by introducing isolated hole‐ and electron‐transporting segments in backbone. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5083–5096, 2005     

金属有机化学气相沉积外延技术生长GaN基半导体发光二极管和激光二极管(Ⅰ)

文章评论性地介绍了金属有机化学气相外延技术（MOCVD）生长氮化物半导体GaN和InGaN以及激子局域化效应、量子束缚斯塔克效应对它们的光学性能的影响，详细比较了这两种效应对GaN基半导体发光二极管和激光二极管特性的影响，特别是量子束缚斯塔克效应以显著不同的方式影响着发光二极管和激光二极管的性能；文章还讨论了在A面蓝宝石衬底上生长GaN的情况．     

Analytical devices based on light-emitting diodes – a review of the state-of-the-art

A general overview of the development of the uses of light-emitting diodes in analytical instrumentation is given. Fundamental aspects of light-emitting diodes, as far as relevant for this usage, are covered in the first part. The measurement of light intensity is also discussed, as this is an essential part of any device based on light-emitting diodes as well. In the second part, applications are discussed, which cover liquid and gas-phase absorbance measurements, flow-through detectors for chromatography and capillary electrophoresis, sensors, as well as some less often reported methods such as photoacoustic spectroscopy.     

黄光类水滑石的制备、表面改性及应用

采用共沉淀法合成了荧光类水滑石材料,该材料在470 nm蓝光激发下可发出黄色荧光(557 nm),采用硅烷偶联剂对其进行表面改性,探讨了表面改性对黄光类水滑石的发光性能、结构及热稳定性的影响。将改性黄光类水滑石与GaN基蓝光芯片封装后制得了白光LED。研究结果表明,改性的黄光类水滑石是制作白光LED可供选用的黄色发光材料。本文成功地将低温一步法制备得到的金属有机配合物/无机纳米杂化材料应用于LED,拓展了LED用荧光粉的选用范围。     

高效大面积有机白光照明研究及其展望

白光有机发光二极管(OLED)是新一代健康节能照明光源,光效性能已超过荧光灯水平。自从OLED技术问世以来,研究人员陆续开展了关于OLED照明的研究工作。本文介绍了OLED照明的特点,以及国内外OLED照明发展现状,讨论了发展OLED照明技术和装备国产化所亟待解决的重大难题和面临的挑战,重点论述了发展高效大面积OLED照明器件制备技术及推动OLED照明产业化的重要意义。     

立体发光LED灯片的光学性能研究

立体发光灯片的关键是在保证光通量的前提下,如何获得均匀的正反面发光.本文对3种荧光粉平面涂覆立体灯片的正面和反面的瞬态和稳态光通量、色温、色品坐标进行了研究,发现直接涂覆荧光粉胶的灯片总的光通量最大,但正反面的发光性能相差很大;在涂覆荧光粉之前先平面涂覆一层硅胶,可获得正反面发光较均匀的灯片;而在该硅胶层内掺杂扩散粉的灯片,不但没有提高灯片的正反面发光均匀度,反而大幅度降低了光通量值.此外,测试3种样品的发光角度,发现其发光角度分布相似,而发光强度与积分球测试的光通量比值相近.结果表明,涂覆荧光粉之前先平面涂覆一层硅胶工艺,既可以保证立体发光灯片具有较大的光通量又可以获得均匀的正反面发光.     

基于BP神经网络的LED可靠性模型研究

根据LED可靠性与相关参数的映射关系,建立拓扑结构为6-12-1的BP神经网络。以实测白光LED芯片的理想因子、结温、色温漂移等参数为输入量,以寿命为输出量,计算模型精度。研究结果表明,该模型有良好的外推能力及鲁棒性,可在短时间内成功预测LED寿命,神经网络训练结果相关系数为99.8%,检验组误差小于3%。