反向偏压调制下Ⅰ型阱结构体系光致发光特性的研究

实验过程中研究了8-hydroxyq-uinoline aluminum(Alq3)和2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole(PBD)构成的Ⅰ型有机阱结构器件在反向偏压调制下的光致发光.器件的光致发光光谱主要是Alq3的发光,不同周期数的阱结构器件在反向电场作用下,光致发光的猝灭程度不同.     

反向偏压调制下Ⅰ型阱结构体系光致发光特性的研究

实验过程中研究了8-hydroxyq-uinoline aluminum（Alq₃）和2-（4-biphenylyl）-5（4-tertbutyl-phenyl）-1,3,4-oxadiazole（PBD）构成的Ⅰ型有机阱结构器件在反向偏压调制下的光致发光。器件的光致发光光谱主要是Alq₃的发光。不同周期数的阱结构器件在反向电场作用下,光致发光的猝灭程度不同。     

电子俘获材料的浓度猝灭

利用稀土直接掺杂工艺对电子俘获材料 Ｃａ Ｓ： Ｅｕ , Ｓｍ 进行了配方优化,确定了最佳的激活剂浓度,并结合光谱测试,分析了引起 Ｃａ Ｓ： Ｅｕ , Ｓｍ 红外上转换发光浓度猝灭的原因     

乙酸溶液荧光猝灭的机理研究

从理论上对紫外光激励乙酸产生荧光及荧光猝灭机理分别进行了分析研究.结果表明,乙酸溶液在253.7nm紫外光照射下可以发出明显的荧光,而且随着溶液浓度的变化产生了荧光猝灭的现象.分析认为,荧光猝灭的主要原因是动态猝灭过程-由最低激发单重态(n,π)转入三重态(π,π)所致,并对淬灭常数进行了计算.研究乙酸本体荧光特性及荧光猝灭机理可为其作为猝灭剂、溶剂、催化剂和食品添加剂时其它分子荧光光谱的研究提供参考.     

基于荧光猝灭原理的塑料光纤溶解氧传感器

为了在线测量微生物燃料电池内溶解氧浓度,提高微生物燃料电池的产电效率,利用荧光猝灭原理,采用邻啡咯啉钌作为荧光标记物,并采用溶胶-凝胶法制备了氧敏感膜.将该敏感膜固定在塑料光纤表面,通过测量荧光指示剂发出的荧光强度实现了对溶解氧浓度的测量.实验结果表明,传感器的相对荧光强度与溶解氧浓度具有较好的线性关系,拟合系数达到0.980 7,且传感器具有良好的可逆性.     

不同粒径的SiO_2纳米粒子与PVK分子复合体系的发光性质研究

通过溶胶-凝胶的方法,在乙醇溶液中合成了40nm和60nm两种不同粒径的SiO2纳米粒子,并将其分别与聚乙烯咔唑(PVK)混和,得到了不同粒径、不同质量分数配比的PVK/SiO2纳米粒子复合体系;利用光致发光光谱、吸收光谱和喇曼光谱,深入研究了PVK分子在不同状态条件下的发光特性和PVK/SiO2纳米粒子复合体系的光学性质;在复合体系中,观察到PVK与SiO2纳米粒子之间的界面能量转移过程,且不同粒径的SiO2纳米粒子对PVK分子的发光性质影响也不同。通过喇曼光谱的进一步研究表明,SiO2纳米粒子的存在,使PVK分子的振动能量明显减小,表明PVK分子与SiO2纳米粒子表面存在较强的相互作用。     

CdSe／PVK纳米晶薄膜及其电致发光特性

以巯基乙酸（RSH）为稳定剂，在水溶液中合成CdSe纳米晶，用表面活性剂将分散在水溶液中的纳米颗粒转移到有机溶剂中，与具有电荷输运性能的有机聚合材料复合。作为电致发光（EL）器件的工作层，得到较强的位于600nm附近的CdSe纳米晶的带边发射，以及较弱的位于420nm附近的来自聚合物的发射。器件EL强度首先随着外加电压的增加而增加，当电压超过26V时，EL强度开始下降。器件的电流-电压（I-V）特性基本符合二极管特性，表明器件是受载流子注入限制的。     

Effect of OA-ZnSe nanoparticles incorporation on the performance of PVK organic photovoltaic cells

The impacts of the Oleic Acid capped ZnSe (OA-ZnSe) nanoparticles content variation on the microstructural and electrical properties of the ITO/PVK:OA-ZnSe/Al hybrid cell have been investigated by using a combination between the FTIR and the electrical measurements. Based on the J-V characteristics of studied hybrid cell in dark, the conduction mechanism for voltages lower than 1.5 V follows the Richardson–Schottky law. On voltages above 1.5 V, the J–V characteristics can be successfully modeled by other theories such as the space-charge limited current (SCLC) or the trap charge limited current (TCLC). Under white light illumination, the J–V characteristics are clearly affected by the incorporation of OA-ZnSe nanoparticles, indicating a significant improvement of the photovoltaic cell parameters, in particular the conversion efficiency which increases 12-fold compared to the cell based on non-doped PVK. The effective photocurrent density Jph of the hybrid cells with different OA-ZnSe contents are also considered.     

The role of exciplex states in phosphorescent OLEDs with poly(vinylcarbazole) (PVK) host

Polymer light emitting diodes (PLEDs) may revolutionize lighting and display industries. PLEDs would enable printing of display or lighting panels on large area substrates that could substantially reduce fabrication costs by avoiding expensive vacuum processes presently used in OLED technologies. PVK is one of the most popular hosts for blue PLEDs. However, PVK has very poor electron transport properties and oxadiazole based electron dopants, e.g. PBD or OXD-7, are used to improve charge transport. This is generally ascribed to capture and transport of electrons on the PBD or OXD-7. Here we show that this is not necessarily the only reason for improved efficiency upon PVK doping. We demonstrate that devices with PVK doped with PBD or OXD-7 have emission lasting up to 1 ms which in some cases may be greater than prompt emission from excitons formed initially on the dopant. This long-lived emission is arising mainly due to formation of an exciplex between the PVK and PBD/OXD-7. This exciplex state then repopulates dopant iridium complexes over a long period of time giving very long-lived emission. We also note that this exciplex-fed long-lived emission from heavy metal complexes is observed in several PLEDs with PBD and PVK (and also OXD-7) doped with blue or green iridium phosphors indicating this to be a general phenomenon.     

CdSe四脚状纳米晶粒的光荧光研究

采用高温微乳液的化学方法,在溶液中合成了高产率的CdSe四脚状纳米晶粒。高分辨透射电镜(HRTEM)分析结果表明,CdSe四脚状纳米晶粒是由1个立方的核心和4个六方的臂所组成。研究了该四脚晶粒的变激发功率光荧光(PL)谱和变温的PL谱,分析发现低温时四脚晶粒的光荧光主要来自于被表面缺陷所局域的激子的辐射复合,而随着温度升高,束缚激子被热激发,室温时光荧光主要来自于自由激子的贡献。CdSe纳米量子点的退局域化温度比四脚纳米晶粒的高,而12K时CdSe纳米量子点的局域化能量比四脚纳米晶粒的也大得多,并对这一现象作了解释。     

Synthesis of Highly Luminescent SnO2 Nanocrystals: Analysis of their Defect‐Related Photoluminescence Using Polyoxometalates as Quenchers

Colloidal semiconductor nanocrystals (NCs), called quantum dots (QDs), have been intensively studied because of their excellent photoluminescence (PL) quantum yields. However, commercial QDs such as CdSe and InP contain toxic or expensive rare elements, limiting their sustainable use. This study focuses on nontoxic, stable, and cheap tin oxides, and synthesized luminescent SnO₂ NCs of ≈2 nm in size by a heating‐up method. Tin precursors and diols in a high‐boiling point solvent with oleylamine as the surfactant are heated at 240 °C. SnO₂ NCs show defect‐related photoluminescence at 400–460 nm by excitation at 370 nm, achieving a high quantum yield of more than 60%. The PL intensity is stable even when the NCs are stored in atmospheric air at room temperature for over 1 year. The defect‐related emissions of the SnO₂ NCs are studied using polyoxometalates (POMs) as the PL quencher. POMs efficiently quench the PL emissions by extracting excited electrons from the conduction band and shallow surface defects. The results reveal that PL emissions from SnO₂ NCs are associated with radiative charge recombination via shallow defect levels on the surface and in the bulk, demonstrating the effectiveness of the PL quenching technique using POMs in studying the PL emission mechanism in QDs.     

变频器在纺丝冷却系统中的应用

本文介绍I／A series控制的变频器纺丝冷却系统。本系统通过I／A series、变频器、压力变送器等设备来实现涤纶短纤维纺丝生产的自动控制。文中详细介绍了系统的组成、控制原理及硬件设计。     

3Cr13不锈钢计数器棘轮的激光淬火研究

利用2KW横流CO_2激光器对3Cr13计数器棘轮进行了激光淬火研究,结合零件的原始加工次序,比较了两种次序激光淬火投弹器棘轮的工艺,结果表明:经两种方法激光处理后棘轮的显微硬度均达到了该零件技术指标的要求,显微硬度为HV412∽550。激光处理3Cr13不锈钢硬化层的深度为1.0mm,表面最高硬度HV680,比普通淬火高约HV160。激光处理后齿面的光洁度不变,达(Ra0.4∽0.3μm),激光淬火的变形为2.5μm左右。激光淬火区的显微组织为细小均匀的隐晶马氏体。