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.     

多孔硅/PVK复合体系的光电性能

用旋涂法实现了多孔硅与聚乙烯咔唑的复合,并研究了不同温度热处理后复合体系的电学和光学性能．实验结果表明：热处理有利于复合体系发光强度的提高;而且当热处理温度不超过120℃,随着热处理温度的升高器件的整流效应增大．同时,复合体系还实现了电致发光,产生了555nm的电致发光峰．     

黄色荧光粉CaBi_2Ta_2O_9:Dy~(3+)的制备及发光性能

采用高温固相反应法制备了Dy3+掺杂铋层结构铁电氧化物CaBi2Ta2O9(CBTO)荧光粉。分别对样品进行了X射线衍射(XRD)分析、扫描电镜(SEM)测试和荧光光谱(PL)的测定。研究表明:荧光粉CBTO:Dy3+的最强激发峰为450 nm,与商用蓝光LED的发射光波长相匹配,发射带峰值位于574 nm,对应于Dy3+的电偶极跃迁4F9/2→6H13/2。分析了Dy3+摩尔分数对样品发光强度的影响,其最佳摩尔分数为7%,根据Dexter理论分析其浓度猝灭机理为电偶极-电偶极相互作用。分别研究了电荷补偿剂Li+、Na+和K+对CBTO:Dy3+发射光谱的影响,结果显示不同的电荷补偿剂均能不同程度地提高样品的发光强度。     

Avoiding trap states in poly(n-vinylcarbazole) thin films

Optical properties of poly(n-vinylcarbazole) (PVK) thin films are revisited. Steady-state emission spectra put in evidence a strong red band whose intensity increases with decreasing temperature when the solid state PVK film is excited by a continuous 375 nm laser line. This red band is assigned to the emission from PVK aggregate states which act as trap states for the monomeric PVK triplet high energy (blue) excitons. At the same low temperatures, these trap states can be avoided when the excitation of the PVK film is made by a 355 nm pulsed laser line with 10 Hz repetition rate. The red band was also observed to compete with the emission of guest poly(3-octadecylthiophene) (PODT) molecules in a PVK/PODT sequential bilayer structure. Different optical geometries enabled us to show that the exciton energy transfer effect from PVK donor to PODT acceptor states dominates the scenario in the bilayer structure, suppressing almost completely the trap state emissions.     

Quenching-Resistant Solid-State Photoluminescence of Graphene Quantum Dots: Reduction of π−π Stacking by Surface Functionalization with POSS,PEG, and HDA

Graphene quantum dots (GQDs) have attracted great attention as next-generation luminescent nanomaterials due to the advantages of a low-cost process, low toxicity, and unique photoluminescence (PL). However, in the solid-state, the strong π−π stacking interactions between the basal planes of GQDs lead to aggregation-caused PL quenching (ACQ), which impedes practical application to light-emitting devices. Here, surface functionalized GQDs (F-GQDs) by polyhedral oligomeric silsesquioxane (POSS), poly(ethylene glycol) (PEG), and hexadecylamine (HDA) to reduce π−π stacking-induced ACQ is presented. The POSS-, PEG-, and HDA-functionalized GQDs show a significant enhancement in PL intensity compared to bare GQDs by 9.5-, 9.0-, and 5.6-fold in spin-coated film form and by 8.3-, 7.2-, and 3.4-fold in drop-casted film form, respectively. Experimental results and molecular dynamics simulations indicate that steric hindrance of the functionalization agent contributes to reducing the π−π stacking between adjacent GQDs and thereby enabling quenching-resistant PL in the solid-state. Moreover, the GQD-based white light-emitting diodes fabricated by mounting HDA-GQDs on a UV-LED chip exhibits efficient down-conversion for white light emission with a high color rendering index of 86.2 and a correlated-color temperature of 5612 K at Commission Internationale de l'Éclairage coordinates of (0.333, 0.359).     

CdS纳米锥的合成以及光致发光性能研究

将商用CdS粉在真空炉中通过简单的热蒸发获得了大量高纯的CdS锥状纳米结构.扫描电子显微镜(SEM)、透射电子显微镜(TEM)观察和X射线衍射谱(XRD)的分析表明:CdS纳米锥状晶体为六角硫镉矿晶体结构,其形状为典型的纳米锥,晶格常数为a=0.413 nm,c=0.671 nm,沿着[0001]方向生长.CdS纳米锥的长度是20 μm到50 μm,直径从～100 nm减少到～20 nm.本文还详细研究了CdS纳米锥晶体的拉曼特性及其在激光辐射下的室温光致发光行为,探讨了绿光(波长为～512 nm)发射的机制.结果表明,这种CdS纳米锥可能用于新颖的光学器件.     

In_xGa_（1－x）As／Al_yGa（1－y）As多量子阱的高压光致发光研究

用金刚石对顶砧压力装置在液氮温度下和０～４ＧＰａ的压力范围内测量了不同阱宽（１．７～１１．０ｎｍ）的ＩｎｘＧａ（１－ｘ）Ａｓ／Ａｌ（１－ｙ）Ｇａ（１－ｙ）Ａｓ（ｘ,ｙ＝０．１５,０;０．１５,０．３３;０,０．３３）多量子阱的静压光致发光谱,发现在Ｉｎ０．１５Ｇａ０．８５Ａｓ／ＧａＡｓ多量子阱中导带第一子带到重空穴第一子带间激子跃迁产生的光致发光峰能量的压力系数随阱宽的增加而减小,在Ｉｎ０．１５Ｇａ０．８５Ａｓ／Ａｌ０．３３Ｇａ０．６７Ａｓ和ＧａＡｓ／Ａｌ０．３３Ｇａ０．６７Ａｓ多量子阱中相应发光峰的压力系数随附宽的增加而增加．根据Ｋｒｏｎｉｙ－Ｐｅｎｎｅｙ模型计算了发光峰能量的压力系数随阱宽的变化关系,结果表明导带不连续性随压力的增加（减小）及电子有效质量随压力的增加是压力系数随阱宽增加而减小（增加）的主要原因．