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.     

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.     

带烷氧基的苯基蒎烯吡啶铱配合物在聚合物电致发光器件中的应用研究

采用旋涂法将一组带烷氧基的苯基蒎烯吡啶铱(Ⅲ)配合物(Ir(RO-pppy)₃)磷光材料掺杂到PVK中,制作出了聚合物电致发光器件:ITO/PE-DOT:PSS(40 nm)/PVK_0.7:PBD_0.3:(x%.)Ir-complex(80 nm)/CsF(1.5 nm)/Mg:Ag(200 nm).实验结果表明,带有长烷氧基链配体的铱(Ⅲ)配合物能表现出更好的器件行为,当掺杂浓度为3.2%时,器件的最高发光效率达19.9 cd/A(7.8 lm/W,9.1V),CIE为(0.20,0.56);器件最大亮度为15700 cd/m²(8.4V).通过对这组铱(Ⅲ)配合物的光物理行为及电化学性能的研究,考察了主体材料与配合物之间的能级配置以及能量转移的机理.     

抗菌医药左氧氟沙星在有机电致发光二极管中的应用

左氧氟沙星(LOFX)是一种知名的抗菌药物, 它的价格非常便宜, 且有成熟的合成和纯化技术. 本文中首次将LOFX作为一种蓝光发光材料和电子传输材料应用于有机电致发光器件(OLED)中. 通过热重分析、UVVis吸收光谱、发射光谱以及循环伏安曲线详细地表征了LOFX的热学及光物理特性. LOFX有高的分解温度,为327 ℃; HOMO、LUMO能级分别为-6.2 和-3.2 eV, 光学带隙为3.0 eV. 以LOFX作为客体材料, 掺杂在主体材料4,4'-二(9-咔唑)联苯(CBP)中制备了蓝光OLED, 该器件的电致发光(EL)发射峰位于452 nm, 最大亮度为2315 cd·m^-2. 进一步, 选择8-羟基喹啉铝(Alq₃)作为参考材料, 分别以LOFX和Alq₃作为电子传输材料制备了结构相同的单载流子器件和绿色磷光OLED. 在相同的电压下, 以LOFX作为电子传输材料的单载流子器件的电流密度比以Alq₃作为电子传输材料的单载流子器件更高. 同时, 以LOFX作为电子传输材料的绿色磷光OLED获得更高的器件效率. 从这些EL性能可以看出, LOFX同时也是一很好的电子传输材料.     

高效溶液法小分子磷光电致发光器件研究

以小分子化合物CDBP[4,4′-bis(carbazol-9-yl)-9,9-dimethyl-fluorene]为主体材料,Ir(pppy)3[tris(5-phenyl-10,10-dimethyl-4-aza-tricycloundeca-2,4,6-triene)Iridium(III)]为磷光客体材料,采用溶液法和真空蒸镀法相结合的制备工艺,制作了小分子磷光电致发光器件.研究表明,通过器件结构的优化,Ir(pppy)3(重量百分比为2)掺杂的多层绿光电致发光器件效率达22.0 cd/A,最大亮度达到26600 cd/m²,这一结果可与当今基于真空蒸镀的小分子或基于溶液法的高分子磷光电致发光器件性能相媲美.本工作为降低有机电致发光器件的成本,扩展溶液法有机电致发光器件制备工艺中材料的选择范围提供了实验依据.     

窄光谱磷光配合物的设计及电致发光性能

通过对螯合配体及辅助配体的设计与筛选, 构筑了一种全新的天蓝光铱金属配合物(MeFPyPy)₂Ir(dipcMePy)(简称MFPMP), 实现了三重态配体中心、 三重态金属-配体电荷转移和/或三重态配体-配体电荷转移跃迁类型混合比例较优化的发光过程. 以MFPMP作为发光体的磷光有机电致发光器件实现了半峰宽为52 nm, 最大发光波长为476 nm的窄光谱、 单峰型、 高亮度、 高效率天蓝光发射, 并在1000 cd/m²的实用亮度下保持了25%以上的外量子效率(EQE), 与目前报道的最高水平有机电致发光器件性能相当. 本工作为进一步开发色纯度更高、 更具有实用性的磷光配合物发光材料提供了一条可行的途径.     

基于香豆素衍生物的新型绿色/红色磷光有机电致发光主体材料的设计、合成及性能表征

设计并合成了一种新型的香豆素衍生物,3,3-’(1,3-苯基)双(7-乙氧基-4-甲基香豆素)(mEMCB),并系统地对该香豆素衍生物进行了结构表征、光物理性能、热物理性能及电化学性能的研究.mEMCB具有较高的三重态能级(2.42eV),可敏化绿色、红色磷光掺杂材料.同时,mEMCB还具有较好的热稳定性(T_g:79.72℃,T_d:361.49℃),其T_g明显高于目前广泛使用的磷光主体材料CBP.研究结果表明,mEMCB是一个潜在的可以用于绿色和红色磷光有机电致发光器件的主体材料.     

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.     

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.     

基于联咔唑为骨架的双极主体材料的合成及其在有机电致发光器件中的应用

咔唑类衍生物具有良好的空穴传输性能和较高的三重态能级,在有机电致发光器件中一般用来构建空穴传输材料和主体材料。本文通过在联咔唑的3和6位引入具有电子传输能力的氰基,设计合成了一种以双咔唑二聚体为分子骨架的新型双极性有机电致发光主体材料6,6’-双氰基-9,9’-二苯基-3,3’-联咔唑（BCzDCN）,研究了其发光性能、热稳定性和电化学性质。低温磷光发射光谱测试表明BCzDCN的三重态能级高于传统的天蓝色磷光掺杂材料双（4,6-二氟苯基吡啶-N,C²’）吡啶甲酰合铱（FIrpic）。以BCzDCN为主体材料,FIrpic和双（4-苯并噻吩）[3,2-C]吡啶-N,C²’）乙酰丙酮合铱（PO-01）分别为蓝色和黄色磷光掺杂材料,制备了蓝色和白色有机磷光发光二极管器件。器件的最大电流效率分别达到34.6 cd/A和59.0 cd/A。并且在1000 cd/m²亮度下的效率滚降仅有4.1%和5.1%。     

Synthesis, characterization and applications of vinylsilafluorene copolymers: New host materials for electroluminescent devices

Vinylsilafluorene (VSiF) was successfully synthesized and copolymerized with vinylcarbazole and methyl methacrylate via free radical copolymerization for the first time. The synthesis, photophysical properties, computational modeling studies, and organic light-emitting devices of the VSiF copolymers were presented. The good coordinated photoluminescent (PL) spectra with the absorption of blue light-emitting materials and the high energy band-gap of the VSiF copolymers were observed. Higher triplet band gap (³ E _g) to host the blue phosphorescent emitters and better HOMO and LUMO than PVK for electron and hole injection and transportation of the VSiF model compounds were revealed by density functional theory (DFT) calculations. The preliminary device results in applications of these copolymers as host materials for green phosphorescent emitters demonstrate the copolymers of VSiF and vinylcarbazole have comparable device performance of polyvinylcarazole (PVK), suggesting a bright future of VSiF as building blocks for host materials.     

Energy transfer and triplet exciton confinement in polymeric electrophosphorescent devices

Energy transfer and triplet exciton confinement in polymer/phosphorescent dopant systems have been investigated. Various combinations of host‐guest systems have been studied, consisting of two host polymers, poly(vinylcarbazole) (PVK) and poly[9,9‐bis(octyl)‐fluorene‐2,7‐diyl] (PF), blended with five different phosphorescent iridium complexes with different triplet energy levels. These combinations of hosts and dopants provide an ideal situation for studying the movement of triplet excitons between the host polymers and dopants. The excitons either can be confined at the dopant sites or can flow to the host polymers, subject to the relative position of the triplet energy levels of the material. For PF, because of its low triplet energy level, the exciton can flow back from the dopants to PF when the dopant has a higher triplet energy and subsequently quench the device efficiency. In contrast, efficient electrophosphorescence has been observed in doped PVK films because of the high triplet energy level of PVK. Better energy transfer from PVK to the dopants, as well as triplet exciton confinement on the dopants, leads to higher device performance than found in PF devices. Efficiencies as high as 16, 8.0, and 2.6 cd/A for green, yellow, and red emissions, respectively, can be achieved when PVK is selected as the host polymer. The results in this study show that the energy transfer and triplet exciton confinement have a pronounced influence on the device performance. In addition, this study also provides material design and selection rules for the efficient phosphorescent polymer light‐emitting diodes. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2681–2690, 2003     

Carbazole compounds as host materials for triplet emitters in organic light-emitting diodes: polymer hosts for high-efficiency light-emitting diodes

A carbazole homopolymer and carbazole copolymers based on 9,9'-dialkyl-[3,3']-bicarbazolyl, 2,5-diphenyl-[1,3,4]-oxadiazole and 9,9-bis(4-[3,7-dimethyloctyloxy]phenyl)fluorene were synthesized and their electrical and photophysical properties were characterized with respect to their application as host in phosphorescent polymer light-emitting diodes. It is shown that the triplet energy of a polymer depends on the specific connections between its building blocks. Without changing the composition of the polymer, its triplet energy can be increased from 2.3 to 2.6 eV by changing the way in which the different building blocks are coupled together. For poly(9-vinylcarbazole) (PVK), a carbazole polymer often used as host for high-energy triplet emitters in polymer light-emitting diodes, a large hole-injection barrier of about 1 eV exists due to the low-lying HOMO level of PVK. For all carbazole polymers presented here, the HOMO levels are much closer to the Fermi level of a commonly used anode such as ITO and/or a commonly used hole-injection layer such as PEDOT:PSS. This makes high current densities and consequently high luminance levels possible at moderate applied voltages in polymer light-emitting diodes. A double-layer polymer light-emitting diode is constructed comprising a PEDOT:PSS layer as hole-injection layer and a carbazole-oxadiazole copolymer doped with a green triplet emitter as emissive layer that shows an efficacy of 23 cd/A independent of current density and light output.     

Tuning of charge balance in bipolar host materials for highly efficient solution-processed phosphorescent devices

A novel bipolar host material, which meets the requirements of high triplet energy, good charge carrier transport properties, high solubility, and film-forming ability at the same time, has been designed and synthesized. Utilizing a new compound as host material, high-efficiency solution-processed blue and white phosphorescent organic light-emitting diodes (PHOLEDs) have been achieved.     

Electroluminescence of poly(N-vinylcarbazole) films: fluorescence, phosphorescence and electromers

We have studied the electroluminescence (EL) properties of pure poly(N-vinylcarbazole) (PVK) films. Three types of light emission in the EL spectrum were observed, attributed to fluorescence, phosphorescence and electromers, respectively. The observation of electrophosphorescence from PVK films at room temperature is very meaningful, indicating that PVK can produce a large number of triplet excitons under an electric field at room temperature. Our results demonstrate clearly the reason why PVK is an excellent host material for phosphorescent polymer light-emitting diodes (PLEDs).     

Organic soluble deoxyribonucleic acid (DNA) bearing carbazole moieties and its blend with phosphorescent Ir(III) complexes

A functionalized deoxyribonucleic acid (Cz‐DNA) was prepared with carbazolyl ammonium lipid as a triplet host material for phosphorescent material system. It is soluble in organic solvents, which facilitates the sample preparation for the absorption and luminescent properties in solid states. A highly soluble iridium complex, Ir(Cz‐ppy)₃ with carbazolyl‐substituted 2‐phenylpyridine ligands was employed for studying the phosphorescence in Cz‐DNA. There is a good overlap between the photoluminescence spectrum of Cz‐DNA and the metal‐to‐ligand charge transfer (MLCT) absorption bands of the iridium complex. This overlap enables efficient energy transfer from the excited state in the host to the MLCT band of Ir(Cz‐ppy)₃. In addition, photoluminescence quantum yield of Cz‐DNA was found to be relatively larger than the copolymer (PCzSt) with vinylcarbazole and styrene. Thus, Cz‐DNA was employed as a triplet host material for fabricating multilayered electrophosphorescence devices via modification of its property by doping 5,4‐tert‐butylhexyl‐1,3,4‐oxadiazole (PBD). After doping 30 wt % PBD and 10 wt % Ir(Cz‐ppy)₃ into Cz‐DNA, we achieved much improvement in electron injection/transport from an adjacent carrier transport layer, resulting in much improved device performances. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1913–1918, 2010     

一种联咔唑类双极性蓝色磷光主体材料的合成及性能

以联咔唑作为电子给体,二苯基磷氧基团作为电子受体,设计合成了双极性蓝色磷光主体材料6,6'-二(二苯基磷氧基)-9,9'-二己基-3,3'-联咔唑(DPDBC)。通过紫外-可见(UV-Vis)、荧光、低温磷光、循环伏安法、热重分析(TGA)、差热分析(DSC)和密度泛函理论(DFT)对其性能及轨道能级等进行了研究。结果表明,化合物DPDBC在CH₂Cl₂稀溶液中有两个吸收峰,最大吸收峰位于306 nm;它的荧光发射峰位于420 nm,属于深蓝色荧光;DPDBC的低温磷光光谱的第一发射峰位于447 nm,其三重态能级为2.77 eV,与蓝色磷光客体材料FIrpic (2.62 eV)的能级相匹配;测定其循环伏安特性曲线,计算得到它的HOMO能级为-5.48 eV,与阳极ITO的功函(-4.5~-5.0 eV)相匹配,LUMO能级为-2.36 eV,接近于电子传输材料PBD(-2.82 eV),表明它具有双极性能;TGA显示其分解温度为410℃,表明热稳定性能优良,DSC显示其T_g温度为140℃,表明其具有无定形态结构及良好的成膜性能。因此,DPDBC是一种集双极性传输性能于一体,同时又具有优良热稳定性能的潜在蓝色磷光主体材料。     

Electroluminescent Properties of an Electrochemically Cross‐Linkable Carbazole Peripheral Poly(Benzyl Ether) Dendrimer

The electroluminescent (EL) properties of a cross‐linkable carbazole‐terminated poly(benzyl ether) dendrimer, G₃‐cbz DN, doped into a PVK:PBD host matrix with a double‐layer device configuration are investigated. Different concentrations of the guest material can control device efficiency, related to chromaticity of white emission and the origin of excited‐state complexes occurring between hole‐transporting carbazole units (PVK or G₃‐cbz DN) and electron‐transporting oxadiazole (PBD). Two excited states (exciplex and electroplex) generated at the interfaces of PVK/G₃‐cbz DN and PBD result in competitive emission, exhibiting a broad band in the EL spectra.