磷光客体三重态能级对基于PVK主体的电致发光器件的影响

将磷光客体掺入PVK:PBD主体材料中是获得高效率磷光电致发光器件 (PhPLED)的有效途径.然而,分别掺杂Ir(pppy)₃、Ir(F-pppy)₃和Ir(F₂-pppy)₃三种磷光客体的PhPLED器件性能件却显著不同.我们分别模拟主-客体间能量转移和客体直接捕获电子空穴对两种机制,研究了三种客体材料的磷光发射及其衰减过程.研究表明:平衡的载流子注入和客体高效率的载流子捕获是实现Ir-配合物掺杂的PhPLED器件性能优良的主要机制,PVK较低的三重态能级使其无法成为蓝光磷光电致发光器件的主体,在PVK中掺入PBD的方法,则进一步降低了主体材料的三重态能级,这是蓝光磷光电致发光器件运行效率较低的主要原因.本文的研究结果可为高分子磷光电致发光器件的制备技术和新型磷光主体的设计提供参考.     

新型黄色磷光吡嗪铱(Ⅲ)配合物的合成及发光性质

利用2,3-二苯基吡嗪与水合三氯化铱反应合成了一种新型吡嗪铱的配合物[Ir(dphp)₂(acac)],通过元素分析,¹HNMR和MS对配合物结构进行了表征,并研究了配合物的吸收光谱和光致发光光谱.利用该材料作为磷光染料制备了结构为[ITO/NPB(30nm)/NPB;8%[Ir(dphp)₂(acac)](25nm)/PBD(10nm)/Alq₃(30nm)/Mg;Ag(质量比9;1)(130nm)的电致发光器件,研究了其电致发光光谱.结果表明,该配合物在393和528nm处存在单重态¹MLCT(金属到配体的电荷跃迁)和三重态³MLCT的吸收峰;荧光光谱结果显示,在588nm处有较强的金属配合物三重态的磷光发射;电致发光光谱显示,该器件的启动电压是3.25V,器件的最大亮度为11478cd/m²,外量子效率为13.85%,器件的流明效率为15.54lm/W,是一种新型的高效率黄色磷光材料.     

以苯基吡唑为主配体的Ir配合物电子结构和光谱性质的密度泛函理论研究

用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)的B3LYP方法对以苯基吡唑ppz为主配体的4种Ir配合物Ir(ppz)₃, Ir(ppz)₂(acac), Ir(ppz)₂(pic)和Ir(ppz)₂(dbm)的电子结构和光谱性质进行了理论研究. 计算结果表明, 辅助配体的改变对Ir配合物的最高占据轨道(HOMO)的影响不大, 但会显著的降低分子最低空轨道(LUMO)的能级, 从而调节Ir配合物的HOMO和LUMO间的能隙. 4种配合物对应的发射跃迁分别为Ir(ppz)₃:d(Ir)+π(ppz)→π*(ppz); Ir(ppz)₂(pic):d(Ir)+(ppz)→π*(pic); Ir(ppz)₂(acac), Ir(ppz)₂(dbm):d(Ir)+π(acacdbm)→π*(acacdbm). 金属配合物的发光颜色可以通过选择合适的辅助配体调节.     

有机多层白光发光二极管

有机多层白光发光二极管贝尔实验室的Ｄｏｄａｂａｌａｐｕｒ等人报道了一种新型的有机多层白光发光二极管。他们利用８－羟基喹啉铝（ＡｌＱ）作为绿光发光层，ＤＣＭ１作为红光发光染料，并合成了系列新的三芳基取代的ｏｘａｚｏｌｅ型蓝光发光染料，经过ＴＰＤ／ｏｘａ...     

Gd2ZnTiO6∶Dy3+, Eu3+单基质白光荧光粉的制备与发光性能

采用溶胶-凝胶法制备出Dy³⁺, Eu³⁺共掺杂Gd₂ZnTiO₆白光荧光粉. 通过X射线衍射(XRD)、 扫描电子显微镜(SEM)、 光致发光(PL)光谱对荧光粉的物相、 形貌及荧光性质进行了表征. 结果表明, 所制备的样品均为双钙钛矿结构, 属于单斜晶系(空间群: P2₁/n), 形貌为2~5 μm无规则形状的颗粒. 在392 nm近紫外光的激发下, Gd₂ZnTiO₆∶Dy³⁺,Eu³⁺荧光粉展现出Dy³⁺的蓝光、 黄光发射以及Eu³⁺的特征红光发射. 此外, 通过调节Dy³⁺和Eu³⁺的掺杂浓度, 可实现低色温的暖白光发射. 基于样品优异的荧光性能, 该荧光粉在近紫外激发白光LED中具有一定的开发潜力.     

含有三苯胺-三唑双极性单元的橙红光阳离子型铱(Ⅲ)配合物的合成及在LEDs中的应用

以2-萘基吡啶(npy)为主配体, N,N-二苯基-4-[4-苯基-5-(吡啶-2-基)-4H-1,2,4-三唑-3-基]苯胺(DPPTA)为辅助配体, 合成了含有三苯胺-三唑双极性结构单元的橙红光阳离子型有机铱(Ⅲ)配合物[(npy)₂Ir(DPPTA)]PF₆. 该配合物的热分解温度高达345 ℃, 从20 ℃升温到100 ℃时, 相对发光强度衰减28.0%, 发光颜色稳定. 其所含的双极性结构单元使其能有效地吸收GaN芯片的蓝光(λ_em,max=455 nm), 进而可被蓝光高效激发. 以GaN蓝光芯片作为激发光源, [(npy)₂Ir(DPPTA)]PF₆为下转换发光材料, 可以制得橙红光LEDs; 进一步与黄光材料Y₃Al₅O₁₂∶Ce³⁺(YAG:Ce³⁺)联用, 可以制得高效的中性白光和暖白光LEDs.     

嵌入硅基多孔氧化铝中的荧光染料的发光性质研究

3种不同的荧光染料被分别嵌入硅基多孔氧化铝模板中,并且在室温下得到了蓝光、绿光和红光波长的荧光发射.实验中同时观测到上述荧光光谱的蓝移现象.研究结果表明,荧光染料沉积在不同的模板(如硅基多孔氧化铝、多孔硅)中,其相互作用的机理是不同的.模板发光机制的差异将直接影响荧光染料的发光性质.     

2-对联苯-8-羟基喹啉锌的合成及其应用于新型白光OLED

合成了一种全新的有机发光材料2-对联苯-8-羟基喹啉锌(Zn[2-(p-biPh)-8-Q-O]₂), 通过¹H NMR, UV-Vis等对配合物的结构进行表征. 利用该材料制备了新型白光有机电致发光器件(OLED), 其结构为: ITO/NPB (N,N'-双(1-萘基)-N,N'-二苯基-1,1'-二苯基-4,4'-二胺)/BCP (2,9-二甲基-4,7-二苯基-1,10-菲咯啉)/Zn[2-(p-biPh)-8-Q-O]₂/Al. 通过调节空穴阻挡层BCP的厚度, 实现了NPB(蓝光发射)和Zn[2-(p-biPh)-8-Q-O]₂(黄光发射)作为器件双发光层的有效复合, 并研究了其发光机理. 当BCP层的厚度为2.0 nm时, 获得了稳定的白色发光; 该器件在6 V电压下启亮, 20 V电压时最大发光亮度达到130 cd/m², 电流效率为0.224 cd/A.     

高效白色磷光有机电致发光器件

采用真空热蒸镀方法以4,4'-bis (carbazol-9-yl) biphenyl (CBP)为主体材料、以bis[2-(4-tert-butylphenyl) benzothiazolato-N,^C2] iridium (acetylacetonate) [(t-bt)₂Ir(acac)]磷光染料为掺杂剂构成黄色发光层, 制备了高效白光的有机电致发光器件(OLEDs). OLEDs的器件结构为indiumtin oxide (ITO)/N,N’-bis-(1-naphthyl)-N,N’-biphenyl-1,1’-biphenyl-4,4’-diamine (NPB)/CBP: (t-bt)₂Ir (acac)/NPB/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/8-hydroxy quinoline aluminum(Alq₃)/Mg:Ag, 从ITO阳极开始的第一层NPB为空穴传输层, 第二层超薄的NPB为蓝色发光层, BCP为空穴阻挡层和激子阻挡层, Alq₃为电子传输层. 结果表明, 器件电压在3 V启亮, 在16.5 V时, 器件的最高亮度达到15460 cd·m^-2; 在4 V时, 器件达到最大流明效率为7.5 lm·W^-1, 器件启亮后所发出的白光光谱在低电压时随电压变化有稍微的移动, 但是都在白光范围内变化. 在电压达到8 V后Commission Internationale I’Eclairage(国际照明委员会) (CIE)色坐标为(0.33, 0.32), 并且光谱及色坐标稳定, 不随电压变化而改变, 与最佳的白光坐标(0.33, 0.33)几乎重合. 同时, 从机理上解释了光谱移动和效率衰减的原因, 并探讨了载流子陷阱和能量传递的关系.     

基于9,9'-螺二芴和萘的纯碳氢主体材料（英文）

利用磷光有机发光二极管的主客体掺杂结构有助于避免三重态激子浓度猝灭,从而提高器件性能.9,9’-螺二芴(SBF)及其衍生物具有独特的正交构型和刚性骨架,具有高玻璃化转变温度、高三线态能级和用作主体材料的潜力.通过引入萘环合成并表征了两种基于SBF的纯碳氢化合物(PHC)磷光发光器件的主体材料,命名为1,4-SBF-Nap和1,8-Oct-Nap.其中,1,8-Oct-Nap分子存在一个有趣的环化反应,形成八原子环结构而不是一般的SBF.以Ir(MDQ)₂(acac)为客体,成功制备了基于这两种主体的红光器件,最大外量子效率(EQE)分别为15.0%和13.7%,证明PHC主体材料在设计上的多样性.     

Solution-processible conjugated electrophosphorescent polymers

We report the synthesis and photophysical study of a series of solution-processible phosphorescent iridium complexes. These comprise bis-cyclometalated iridium units [Ir(ppy)(2)(acac)] or [Ir(btp)(2)(acac)] where ppy is 2-phenylpyridinato, btp is 2-(2'-benzo[b]thienyl)pyridinato, and acac is acetylacetonate. The iridium units are covalently attached to and in conjugation with oligo(9,9-dioctylfluorenyl-2,7-diyl) [(FO)(n)] to form complexes [Ir(ppy-(FO)(n))(2)(acac)] or [Ir(btp-(FO)(n))(2)(acac)], where the number of fluorene units, n, is 1, 2, 3, approximately 10, approximately 20, approximately 30, or approximately 40. All the complexes exhibit emission from a mixed triplet state in both photoluminescence and electroluminescence, with efficient quenching of the fluorene singlet emission. Short-chain complexes, 11-13, [Ir(ppy-(FO)(n)-FH)(2)(acac)] where n = 0, 1, or 2, show green light emission, red-shifted through the FO attachment by about 70 meV, but for longer chains there is quenching because of the lower energy triplet state associated with polyfluorene. In contrast, polymer complexes 18-21 [Ir(btp-(FO)(n))(2)(acac)] where n is 5-40 have better triplet energy level matching and can be used to provide efficient red phosphorescent polymer light-emitting diodes, with a red shift due to the fluorene attachment of about 50 meV. We contrast this small (50-70 meV) and short-range modification of the triplet energies through extended conjugation, with the much more substantial evolution of the pi-pi* singlet transitions, which saturate at about n = 10. These covalently bound materials show improvements in efficiency over simple blends and will form the basis of future investigations into energy-transfer processes occurring in light-emitting diodes.     

Synthesis and Luminescent Properties of Iridium Complexes with Reduced Concentration Quenching Effect

Three novel cyclometalated ligands 1-benzyl-2-phenyl-1H-benzoimidazole(BPBM), 1-(4-methoxy-benzyl)-2-(4-methoxy-phenyl)-1H-benzoimidazole(MBMPB) and 4-[2-(4-dimethylamino-phenyl)-benzoinidazol-1-ylmethyl]-phenyl-dimethyl-amine(DBPA) were designed and synthesized, and the corresponding highly efficiency green-emitting phosphorescent iridium complexes Ir(BPBM)₂(acac)(1), Ir(MBMPB)₂(acac)(2) and Ir(DPBA)₂(acac) (3) with acetylacetone(acac) as auxiliary ligand were also synthesized. The ligands are functionalized by bulky non-planarity substituents, thus the phosphorescent concentration quenching is substantially suppressed, and all the complexes exhibit bright photoluminescence(PL) in solid state. The photo-physical properties of the three iridium complexes were researched in detail. The results indicate that they have potential application in fabricating non-doped electrophosphorescence device.     

p型结构的高效有机白光器件

制备了一种高效的p型结构的红光有机发光器件.对比发现这种p型结构的器件在亮度、电流密度以及效率等方面都优于普通的器件.将这种p型结构应用到白光器件上,使用红、绿、蓝三种发光材料作为发光层,通过调节它们各自的发射强度来实现白光发射.优化条件后,制得白光器件的最大电流效率和功率效率分别为19.3cd.A-1和12.1lm.W-1,最大亮度可达到31770cd.m-2,在5到11V驱动电压范围内为较纯正的白光,器件的可重复性好.     

蓝色有机电致发光材料及器件的研究进展

有机电致发光器件因在全彩平板显示和固态照明领域中具有广阔的应用前景, 而受到人们的广泛关注。 时至今日, 与现有的红色和绿色有机电致发光材料和器件相比, 具有优越综合性能的蓝色有机电致发光材料和器件却始终匮乏。 相对而言, 蓝光材料具有较宽的能隙, 因而很难获得低电压、高效率和良好稳定性的深蓝光器件。 通常, 白色有机电致发光器件可以通过混合三基色或者两种颜色的方法获得。 但是无论哪种方法, 蓝光材料均是必不可少的。 另外, 还可以通过能量传递将蓝光转化为红光和绿光。 因此, 研发出具有优越综合性能的蓝光材料对有机电致发光器件的推广及应用十分关键。 本文综述了近年来蓝色荧光材料、蓝色磷光材料的研究进展以及蓝光材料在蓝色和白色有机电致发光器件中的应用, 并结合现有工作, 对蓝色有机电致发光材料的研究和应用前景进行展望。     

Highly phosphorescence iridium complexes and their application in organic light-emitting devices

A new series of iridium(III) mixed ligand complexes TBA[Ir(ppy)(2)(CN)(2)] (1), TBA[Ir(ppy)(2)(NCS)(2)] (2), TBA[Ir(ppy)(2)(NCO)(2)] (3), and [Ir(ppy)(2)(acac)] (4) (ppy = 2-phenylpyridine; acac = acetoylacetonate, TBA = tetrabutylammonium cation) have been developed and fully characterized by UV-vis, emission, IR, NMR, and cyclic voltammetric studies. The lowest energy MLCT transitions are tuned from 463 to 494 nm by tuning the energy of the HOMO levels. These complexes show emission maxima in the blue, green, and yellow region of the visible spectrum and exhibit unprecedented phosphorescence quantum yields, 97 +/- 3% with an excited-state lifetimes of 1-3 micros in dichloromethane solution at 298 K. The near-unity quantum yields of these complexes are related to an increased energy gap between the triplet emitting state and the deactivating e(g) level that have been achieved by meticulous selection of ligands having strong ligand field strength. Organic light-emitting devices were fabricated using the complex 4 doped into a purified 4,4'-bis(carbazol-9-yl)biphenyl host exhibiting a maximum of the external quantum efficiencies of 13.2% and a power efficiency of 37 lm/W for the 9 mol % doped system.     

一类以菲衍生物为配体的新型红色到近红外磷光配合物的合成及其光致和电致发光性质

以2-(菲-9)-吡啶、1-(菲-9)异喹啉和喹喔啉并[2,3-l]菲为配体,合成了3个新颖的红色到近红外磷光配合物(pypt)2Ir(acac)、(sqpt)2Ir(acac)和(qupt)2Ir(acac).对这些配合物的吸收、发射光谱和电化学性质进行了研究,结果发现,菲取代基的性质主要影响配合物的LUMO能级,随着菲取代基共轭程度的增加,吸收光谱和发射光谱红移,光致发光(PL)光谱从619 nm红移到704 nm.将4%的(sqpt)2Ir(acac)掺杂在PVK+PBD主体材料中制备了掺杂磷光发光器件,器件电致发光(EL)光谱的λmax为704 nm,器件的EL光谱从红色一直延伸到近红外区域.     

High-efficiency red-light emission from polyfluorenes grafted with cyclometalated iridium complexes and charge transport moiety

We report a new route for the design of electroluminescent polymers by grafting high-efficiency phosphorescent organometallic complexes as dopants and charge transport moieties onto alky side chains of fully conjugated polymers for polymer light-emitting diodes (PLED) with single layer/single polymers. The polymer system studied involves polyfluorene (PF) as the base conjugated polymer, carbazole (Cz) as the charge transport moiety and a source for green emission by forming an electroplex with the PF main chain, and cyclometalated iridium (Ir) complexes as the phosphorescent dopant. Energy transfer from the green Ir complex or an electroplex formed between the fluorene main chain and side-chain carbazole moieties, in addition to that from the PF main chain, to the red Ir complex can significantly enhance the device performance, and a red light-emitting device with the high efficiency 2.8 cd/A at 7 V and 65 cd/m2, comparable to that of the same Ir complex-based OLED, and a broad-band light-emitting device containing blue, green, and red peaks (2.16 cd/A at 9 V) are obtained.     

聚合物掺杂的高亮度磷光有机电致发光器件

采用新型贵金属铱的配合物(pbi)2Ir(acac)作为客体磷光发光材料, 分别以4%和5%(w)的浓度掺杂于聚合物主体材料poly(N-vinylcarbazole) (PVK)中, 利用旋涂工艺制备了结构为indium-tin oxide (ITO)/PVK:(pbi)2Ir(acac)/2,9-二甲基-4,7-二苯基-1,10-菲咯啉(BCP)/Mg:Ag的有机电致发光器件, 对磷光材料(pbi)2Ir(acac)的紫外-可见吸收光谱﹑光致发光光谱以及聚合物掺杂的磷光器件的电致发光特性进行了研究. 结果表明, 两种掺杂浓度的器件均具有8 V左右的启亮电压, 器件在启亮后的最大流明效率分别为1.53和1.31 lm·W-1, 最大亮度分别为11210和9174 cd·m-2; 同时, 器件的电致发光光谱与色坐标均不随偏置电压和客体掺杂浓度的变化而改变, 具有稳定的色纯度. 分析了主体材料PVK到磷光客体(pbi)2Ir(acac)的能量转移机制, 并探讨了随着器件电流密度和客体掺杂浓度的逐渐增加, 器件流明效率的变化趋势.     

Efficient and Low-voltage Phosphorescent Organic Light-emitting Devices Based on Blue Iridium Complex Host

By adopting a phosphorescent host/guest system consisting of blue iridium complex as host and a series of phosphorescent dyes as guest, efficient and low-voltage monochromic organic light-emitting devices(OLEDs) were fabricated. The devices with blue iridium host have higher power efficiency than the device with the conventional host 4,4'-N,N'-dicarbazole-biphenyl. The enhancement of the maximum power efficiency in green phosphorescent device can reach 37.2%. Dichromatic white OLED could be achieved by simply adjusting the concentration of the orange dyes. At a brightness of 1000 cd/m², the power efficiency of the white device is 8.4 lm/W with a color rendering index of 76.