有机发光器件中空穴注入对负电容的影响

对不同结构的有机发光器件(OLED)进行了电容-电压(C-V)特性测量,研究了不同空穴注入结构对OLED负电容的影响。结果表明,负电容的产生与OLED内部电场的分布有着密切的关系,负电容开始出现的频率与电压的平方根呈指数关系。与超薄的单层空穴注入层相比,掺杂的空穴注入层不仅能降低器件的驱动电压,而且其载流子传输特性和出现负电容时的初始电压对频率有着更强的依赖性。     

白光有机电致发光器件发光稳定性研究

基于红绿/蓝双发光层,制作了结构为ITO/MoO ₃(10nm)/NPB(40nm)/TCTA(10nm)/CBP:R-4B(2%):GIR1(14%,X nm)/mCP:Firpic(8%,Y nm/BCP(10nm)/Alq₃(40nm)/LiF(1nm)/Al( 100nm)的白色全磷光有机电致发光器件(OLED),通过 调节红绿发光层的厚度X与蓝光发光层的厚度Y,研究了不同发光层厚度器件发 光性能的影响。研究发现:当X 为23nm、Y为7nm时,器件的光效和色坐标都具有 很高的稳定性,在电压分别为5、 10和15V时,色坐标分别为(0.33,0.37)、(0.33,0. 37)和(0.34,0.38);在电压为 5V时,电流密度为0.674mA,亮度为158.7cd ,最大电流效率为26.87cd/A;利用电子阻 挡材料TCTA和空穴阻挡材料BCP能够显著提高载流子的复合效率。分析认为:发光层顺序 为红绿/蓝时,更有利于蓝光的出射,从而使白光的色坐标更稳定。     

基于BAlq的有机电致发光器件的磁效应

研究了ITO/NPB(40nm)/BAlq(60nm)/BCP(5nm)/LiF(0.8nm)/AI有机电致发光器件(OLED)的磁效应.实验结果表明,磁场在10mT时,器件的效率最大增加了34%,这一结果是由于三线态激子与三线态激子间的相互淬灭产生激发单线态激子从而使单线态激子比率增加,致使电致发光(EL)增强.当磁...     

基于混合配体Znq(DBM)的单色和白色OLED

以8-羟基喹啉(q)和1,3-二苯基-1,3-丙二酮定向合成了有机小分子配合物Znq(DBM),将其作为发光层制备了单色有机电致发光器件(OLED)。在结构为ITO/m-MTDATA(5nm)/NPB(40nm)/Znq(DBM)(60nm)/LiF(0.5nm)/Al(100nm)的器件中,启亮电压为5V,最大亮度达到4 575cd/m2。同时又在器件中引入间隔层BCP,研究其不同厚度对OLED性能的影响。在结构为ITO/m-MTDATA(5nm)/NPB(40nm)/BCP(x nm)/Znq(DBM)(60nm)/LiF(0.5nm)/Al(100nm)的器件中,当BCP层厚为0nm时,发光颜色为黄绿色;当BCP层厚为1nm时,发光颜色为白色,色坐标为(0.29,0.33),最大亮度为2 231cd/m2;当BCP层厚为5nm时,发光颜色为蓝色。根据器件结构和性能,讨论了其内部机理。     

高亮度微腔有机电致发光器件

为了实现有机电致发光器件(OLED)发射光谱的窄化和高亮度,真空热蒸镀具有不同微腔结构的OLED(MOLED):玻璃衬底/分布式布拉格反射器(DBR)(1～4对的SiO2/Ta2O5层)/ITO/空穴传输层(HTL,α-NPD)/发光层(EML,Alq3:Rubrene或Alq3:Coumarin6)/电子传输层(ERL,Alq3)LiF/Mg/Ag,其中沉积DBR结构采用电子束沉积法。实验表明:该MOLED的发射光谱半波长宽度(FWHM)随DBR层数的增加而减小至最小值10nm;并且在2层DBR时,掺杂Rubrene器件得到更大的电流效率,约20cd/A,最大亮度为2.6×105cd/m2。研究发现,蓝光MOLED能够对自发光产生吸收现象,降低了出光效率。     

基于纳米压印PET基底的高效柔性有机电致发光器件

为了克服现有的以玻璃为基底、ITO为电极的有机电致发光器件（OLED）的韧性差、对裂纹缺陷敏感等固有缺点,对现有的OLED器件结构进行优化。本文提出了以PET为基底,旋涂高导PEDOT：PSS作为阳极的高效柔性OLED器件结构。并在此基础上,通过纳米压印蛾眼模板将光耦合结构引入器件,提高器件的光取出效率。此绿光FOLED器件在亮度为1 000 cd·m^-2时,功率效率为36.10 lm·W^-1。在此基础上,通过纳米压印引入光耦合结构的柔性OLED器件表现出良好的光电性质,在亮度为1 000 cd·m^-2时,功率效率可达到80.46 lm·W^-1。并且这种绿光柔性OLED器件在以器件半边长为曲率半径180°弯折200次后亮度衰减很少。此种高导PEDOT：PSS电极和柔性PET基底可以成为较好的ITO透明电极和刚性玻璃基底的替代物,为生产可穿戴式设备提供了可能。     

High efficiency and non-color-changing orange organic light emitting diodes with red and green emitting layers

We report a high performance orange organic light-emitting diode (OLED) where red and green phosphorescent dyes are doped in an exciplex forming co-host as separate red and green emitting layers (EMLs). The OLED shows a maximum external quantum efficiency (EQE) of 22.8%, a low roll-off of efficiency with an EQE of 19.6% at 10,000 cd/m², and good orange color with a CIE coordinate of (0.442, 0.529) and no color change from 1000 to 10,000 cd/m². The exciplex forming co-host system distributes the recombination zone all over the EMLs and reduces the triplet exciton quenching processes.     

阴极蒸镀和隔离层对有机发光二极管性能的影响

制备了简单结构的有机发光二极管(OLED)ITO/NPB/Alq3/Al/Ag。实验结果表明,快速蒸镀法制备的Ag阴极越厚,器件性能越差,而慢速蒸镀200nmAg阴极时器件性能也较差。在Alq3与Al阴极之间插入BCP/C60/LiF隔离层后,即使快速蒸镀法制备的Ag厚达280nm,器件的最大电流密度、最大亮度和最大电流效率仍分别高达248.6mA/cm2、5380.7cd/m2和3.52cd/A。隔离层不仅保护NPB和Alq3基本不被玻璃化,还很好地与Alq3和Al阴极匹配,大大提高了器件性能。     

红绿掺杂有机电致发光器件发光性能的研究

制备了结构为ITO/MoO₃(x nm)/NPB(40nm)/CBP:14%GIr1(12.5nm)/CBP:6%R-4b(5nm)/C BP:14% GIr1(12.5nm)/BCP(10nm)/Alq₃( 40nm)/LiF(1nm)/Al(100nm)的红绿磷光器件,G Ir1和R-4B分别为新型绿色和 红色磷光染料,采用绿-红-绿掺杂顺序,结合BCP对空穴的有效限制作用,研究了不同MoO ₃厚度器件的发光 机理。结果表明,在MoO₃为40nm时,器件发光性能较好,在电压 为5V、亮度为100cd·m－2时,得到最大的 电流效率为16.91cd·A－1。为提高器件光效,增加TCTA电子 阻挡层,获得了最高电流效率20.01cd·A－1。原因主要是, TCTA的HOMO能级介于NPB和CBP之间,促进空穴注入;TCTA较高的三线态能量对发光层激子的 限制。     

Hole injection polymer effect on degradation of organic light-emitting diodes

Polythienothiophene:poly(perfluoroethylene-perfluoroethersulfonic acid) (PTT:PFFSA) has been used to enhance hole injection into small molecule OLEDs. Compared to devices with polyethylene dioxythiophene polystyrene sulfonate (PEDOT:PSS) as the hole injection layer (HIL), the OLED using PTT:PFFSA as a HIL gives enhanced efficiency and a slower luminance decay as well as a slower rise in operating voltage. Further studies of capacitance–voltage characteristics reveal that positive trapped charges accumulate in the hole transporting layer during operation. These results thus highlight the significance of hole injection layer to OLED operational stability.     

一种新型蓝色有机电致发光器件及其发光机理

利用5,6,11,12-tetraphenylnaphthacene(Rubrene)超薄层制备了一种蓝光有机电致发光器件(OLED),器件结构为ITO/N,N'-diphenyl-N,N'-bis(1-naphthyl)-(1,18-biphenyl)-4,4'-diamine(NPB)(50nm)/2,9-d...     

Optical and electrical effects of nickel oxide interlayer for anode-recessed organic light-emitting diodes

Forming a nickel oxide (NiO_x) layer on recessed indium tin oxide (ITO) anodes has successfully enhanced the current efficiency of an organic light emitting diode (OLED) by up to 46%. The recesses largely increased the haze of ITO film and led to a 32.8% current efficiency enhancement of a planar OLED. The introduced NiO_x interlayer allowed another 12.9% efficiency enhancement mainly due to lowered potential barrier at the ITO/organic interface and further elevated haze that led to a more efficient light extraction.     

高饱和度蓝色磷光有机发光器件

使用典型天蓝色磷光材料FIrpic作为磷光金属微腔有机发光器件（OLED）的发光层,以高反射的Al膜作为阴极顶电极和半透明的Al膜作为阳极底电极,采用空穴和电子注入层MoO3和LiF,制备了结构glass／Al（15nm）／MoO3（znm）／NPD（40nm）／mCP：Flrpic（30Ftm,7％）／BCP（20n...     

加入电子阻挡层的黄色磷光有机电致发光器件

使用绿色磷光材料GIr1和红色磷光材料R-4B作 为掺杂剂,制备了一种黄色磷光有机电致发光 器件(OLED),其结构为ITO/MoO₃(60nm)/NPB(40nm)/TCTA(x nm,x＝0、5、10和15)/CPB:GIr1:R -4B(30nm,14%,2%) /BCP(10nm) /Alq₃(40nm)/LiF(1nm)/Al( 100nm)。其中x＝0,5,10,5nm。通过在发光层与空穴传输层之间增 加电子阻挡层TCTA,使器件的效率得到提高。当TCTA厚为10nm时, 起亮电压为4V左右,器 件的最大发光效率为20.2cd/A,最高亮度可以达到21840cd/m²,器件的色坐标 为(0.42,0.53)。器件的EL主峰位于524nm 和604nm。并且当电流 密度为2.49mA/cm²时,10nm厚的TCTA 电子阻挡层的器件发光效率是不加入TCTA的器件发光效率的2倍。发光效率的提高是由于电 子阻挡层的加入限制了空穴传输层NPB的发光,从而使更多的激子在发光层中复合。     

Design of white tandem organic light-emitting diodes for full-color microdisplay with high current efficiency and high color gamut

Microdisplays based on organic light-emitting diodes (OLEDs) have a small form factor, and this can be a great advantage when applied to augmented reality and virtual reality devices. In addition, a high-resolution microdisplay of 3000 ppi or more can be achieved when applying a white OLED structure and a color filter. However, low luminance is the weakness of an OLED-based microdisplay as compared with other microdisplay technologies. By applying a tandem structure consisting of two separate emission layers, the efficiency of the OLED device is increased, and higher luminance can be achieved. The efficiency and white spectrum of the OLED device are affected by the position of the emitting layer in the tandem structure and calculated via optical simulation. Each white OLED device with optimized efficiency is fabricated according to the position of the emitting layer, and red, green, and blue spectrum and efficiency are confirmed after passing through color filters. The optimized white OLED device with color filters reaches 97.8% of the National Television Standards Committee standard.     

采用碳纳米管导电薄膜作为OLED的阳极

采用碳纳米管(CNT)替代ITO作为OLED阳极可以 解决ITO薄膜存在的可弯曲性能差,可靠性低等缺 点,使得柔性显示成为可能。本文采用混合型CNT导电薄膜作为阳极,探讨了CNT薄膜的制备 工艺、掺 杂方式及表面修饰等因素对绿光OLED性能的影响。实验结果表明,P型掺杂对CNT薄 膜的导电性能影响 有限;而PEDOT修饰层可以很好的提高CNT导电薄膜的平整度;此外,采用“十字交叉 ”的阳极形状有助于降低 阳极拐角处毛刺。通过优化器件各参数,制备的PET/CNTs/PEDOT/NPB/ALq₃/LiF/Al绿光OL ED发光效率达 到了195 cd/m²,结果表明采用混合型CNT作为OLED阳极是可行的。     

Stable solution processed hole injection material for organic light-emitting diodes

A new aqueous based polymer, Plexcore® OC AQ1200 (AQ1200) was used as a hole injection layer (HIL) in organic light emitting diodes (OLEDs) and the device results are compared with polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS) in terms of injection efficiency and stability. Dark injection transient measurements show a higher injection efficiency in hole-only devices using AQ1200 HIL compared with PEDOT:PSS. Using AQ1200 as an HIL, high efficiency phosphorescent OLEDs are demonstrated to have a long lifetime, with an estimated operational half lifetime (LT 50) of more than 8000 h from an initial luminance of 1000 cd/m².     

Temperature-dependent minority-carrier lifetime measurements of red AlGaAs light emitting diodes

Electroluminescent decay and internal quantum efficiency measurements are made as a function of temperature on two double heterostructure AIGaAs light emitting diodes (LEDs) that emit in the visible (red) portion of the spectrum. The electroluminescent lifetimes increase by more than a factor of ten and the internal quantum efficiency falls by a factor of three as the temperature is raised from 90 to 400K. By analyzing the data with a model that accounts for the transfer with increasing temperature of the minority-carrier electrons from the direct-gap to the indirect-gap minima in the p-type active layer of these near-crossover LEDs, values for the radiative and nonradiative lifetimes as a function of temperature are obtained. A fit to the radiative-lifetime data results in an estimate of 1.3 × 10⁻¹⁰ cm³s⁻¹ for the room-temperature radiative recombination coefficient of Al_0.39Ga_0.61As, which is very similar to values reported for GaAs. The nonradiative lifetimes are found to be nearly independent of temperature from 220 to 400K and provide upper limits of 940 and 1250 cms⁻¹ for the interface recombination velocities of the two samples. These values are roughly an order of magnitude lower than any previously reported values for high-Al-content (x > 0.3) Al_xGa_1−xAs heterostructures.     

Efficient nondoped organic light-emitting diodes with Cu complex emitter

In Cu^I complex based organic light emitting diodes (OLEDs) a host matrix is traditionally thought to be required to achieve high efficiency. Herein, it is found that the device ITO/MoO₃ (1 nm)/4,4′-N,N′-dicarbazole-biphenyl (CBP, 35 nm)/[Cu(μ-I)dppb]₂ (dppb = 1,2-bis[diphenylphosphino]benzene, 20 nm)/1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi, 65 nm)/LiF (1 nm)/Al (100 nm) with a vacuum thermal evaporated nondoped Cu^I complex emissive layer (EML) showed external quantum efficiency and current efficiency of 8.0% and 24.3 cd/A at a brightness of 100 cd/m², respectively, which are comparable to the maximum efficiencies reported in an optimized doped OLED with the same emitter, higher efficiency than the OLED with a [Cu(μ-I)dppb]₂:CBP EML, and much higher efficiencies than the nondoped OLED with a bis(2-phenylpyridine)(acetylacetonate)iridium [Ir(ppy)₂(acac)] EML. A series of reference films and single carrier devices were fabricated and studied to understand the difference between Cu^I and Ir^III complex based nondoped OLEDs.     

为移动显示设计的有源矩阵OLED

有源矩阵有机发光二极管器件是移动应用市场很有吸引力的显示器。开发者们正迅速地逐步克服技术上的弱点。