有机电致发光器件中的阳极界面修饰的特点与类型

阳极界面修饰作为简单易行的工艺和方法,可以有效地改善有机电致发光器件的性能而得到广泛应用.本文综述了有机电致发光器件中阳极界面修饰的基本特征和类型.结合修饰材料制备工艺和特牲,介绍了各种ITO阳极界面修饰的原理和应用.     

有机电致发光器件中阴极界面修饰的材料、方法及分类

综述了有机电致发光器件中阴极界面修饰的材料、方法和分类.着重介绍了LiF/Al薄绝缘层/金属复合电极在小分子和聚合物器件中的实验结果和各种原理分析,同时阐述了使用薄绝缘层/金属复合电极作为阴极界面修饰的能级模型和理论模拟.     

有机电致发光的研究进展及展望

对有机电致发光(OLEDs)的研究进展进行了综述。内容包括:有机电致发光器件的阴、阳极材料、电极修饰、发光材料、发光效率、新的器件结构以及驱动电路的研究现状。剖析了该领域的研究热点,并展望了其发展应用前景。     

有机电致发光器件的效率及寿命

有机电致发光器件的效率取决于电子和空穴的有效注入和复合.电极材料和有机材料的稳定性以及电极/有机层之间的界面处的相互作用是制约有机电致发光器件寿命的主要因素.     

不同空穴注入电极对有机薄膜电致发光性能的影响

成功地制备了用铝掺杂的氧化锌（ＡＺＯ）透明导电膜作阳极的有机薄膜电致发光器件，并对单层和双层结构的ＡＺＯ器件以及以两种不同ＩＴＯ作阳极器件的电致发光光谱，电流电压特性，亮度电压特性以及电致发光量子效率进行了详细的比较分析和讨论。     

有机-无机杂化光电导电极修饰材料研究进展

有机太阳电池(OPVs)和有机发光二极管(OLEDs)的阴极界面通常由有机小分子、聚电解质以及低温溶胶-凝胶法加工的金属氧化物(最常见的为ZnO)制备而成,由于这些材料导电性不佳使光电器件中阴极界面薄膜厚度限制在30 nm以下,给大面积生产提出了苛刻要求。有机-无机杂化的光电导材料是近来提出的有效提高阴极界面材料电导率的新策略。有机分子具有较高的消光系数,能够在低掺杂浓度下高效吸收可见光,而金属氧化物具有较高的电子迁移率,从有机分子到金属氧化物的光致电子转移能够有效填充金属氧化物中的电子陷阱(缺陷),同时大幅度增加金属氧化物中的载流子密度,因而,这种有机-无机杂化的电极修饰材料具有优异的光电导性能。最近,报道通过掺杂一类苝酰亚胺光敏剂到无定形ZnO薄膜中,显著提高ZnO薄膜在光照下的电导率,解决了ZnO薄膜电导率低的科学问题。将这种杂化的光电导材料用于OPVs与OLEDs器件中,显著提高了器件性能,同时大幅度降低了电极修饰薄膜厚度对器件性能的影响,为大面积器件的快速制备提供了有利条件。     

用原子力显微镜分析Al2O3抛光处理的ITO玻璃表面形貌

利用原子力显微镜(AFM)研究有机电致发光器件的阳极材料铟锡氧化物(ITO)玻璃的表面形貌.结果表明,用不同粒度Al2O3抛光液处理以及用相同粒度Al2O3抛光液在不同超声时间处理的ITO表面形貌都有不同程度的变化,所制备的有机电致发光器件(OLED)性能也有相应的改变,制备的OLED的最大亮度由12 350 cd/m2提高到25 880 cd/m2,最大效率也提高了50%.基于AFM形貌研究,确定了OLED的优化条件.     

TMEP作为缓冲层增加有机发光器件的效率的研究

在有机发光器件中的发光层和阴极之间插入了稳定性好、有良好电子传输能力的苝酸四甲酯(TMEP)新型缓冲层,改善了有机电致发光器件的亮度和发光效率.在电流密度为200mA/cm2时,有缓冲层的器件B效率为0.82cd/A,没有缓冲层的器件A效率为0.14cd/A.     

有机发光器件(OLED)中的界面研究

有机电致发光器件由于其成本低、重量轻、低阈值电压、高亮度、无需背光源而自身发光、宽视角并易于加工等优点成为现代平板显示的研究热点.经过了二十余年的发展,OLED的器件性能得到大幅度改善.然而,距离实用化还有一定差距,如发光效率低以及器件寿命短等问题,成为制约其推广应用的技术瓶颈.OLED的器件性能在很大程度上由其器件中的界面结构所决定.简要介绍OLED中的界面研究进展,围绕金属/有机界面、有机/有机界面、阳极/有机界面以及层内部材料界面展开叙述,讨论界面结构与OLED器件性能之间的关系,并以多种技术手段和方法研究OLED界面分子结构、能带结构、激发态特性及反应等获得的主要结果,在此基础上预测OLED界面研究的发展趋势.     

白色有机发光材料与器件

综述了白色有机电致发光材料和器件的研究进展;归纳了获取白色有机电致发光的途径和方法;分析了多种器件结构的特点及其材料;结合研究过程中存在的某些问题,从器件的发光效率和色纯度角度,讨论了影响发光器件性能的诸因素及其改进措施.     

Improving the efficiency of organic electroluminescent devices by introducing an electron-accepting and thermally stable polymer

A new hole-transporting material for multi-layer organic electroluminescent devices (OELDs) was prepared by the copolymerization of a hole-transporting material (9-vinyl carbazole) and an electron-retarding material (bis-4-vinylbenzyl-4,4^′-dipyridinium chloride). The resulting polymer has good thermal stability and electron-retarding property, due to its chemical structure and the 4,4^′-dipyridyl groups, respectively. The OELDs were fabricated with a multi-layer structure of an anode/new polymeric hole-transporting layer (HTL)/emitter/cathode. It was found that the electroluminescence efficiency was improved by using an electron-retarding material in a HTL.     

原子力显微镜与X射线光电子能谱对ITO表面改性的研究

采用氧气等离子体(OP)处理对氧化铟锡(ITO)薄膜进行表面改性,通过原子力显微镜(AFM)、X射线光电子能谱(XPS)和四探针等测试手段对薄膜样品进行表征,研究了OP处理对ITO表面性质的影响.实验结果表明OP处理有效去除了ITO表面的污染物,优化了ITO表面的化学组分,降低了ITO表面的粗糙度和方块电阻,改善了ITO的表面形态.与此同时,通过XPS监测研究了OP处理后ITO表面化学组分随老化时间的变化,结果显示经过优化的化学组分随老化时间增加而逐渐退化.另外,以OP处理后经过不同老化时间的ITO样品作为空穴注入电极,制备了有机电致发光器件(OELD),通过测试器件的电压-电流-亮度特性,进一步研究了ITO表面性质对于OELD光电性能的影响.     

Efficient top-emitting organic light-emitting diodes with Sm/Ag bilayer cathode

A bilayer is used as a semitransparent cathode for top-emitting organic light emitting devices (top-emitting OLEDs). The bilayer cathode consists of samarium (Sm) and silver (Ag). Top-emitting OLEDs with the bilayer cathode showed enhanced current injection and high electroluminescence efficiency as compared with a Sm cathode. The maximum current efficiency of the top-emitting OLEDs with a Sm/Ag cathode is 9.9 cd/A, much greater than 4.9 cd/A obtained from the top-emitting OLEDs with a Sm cathode. The improved performance can be attributed to the balance between optical transparency and electrical conductivity of the Sm/Ag cathode.     

PAA类黏结剂在锂电池中电化学性能研究进展

黏结剂是维持极片完整性必不可少的部分,对电池比容量、循环稳定等性能的提高非常重要。聚丙烯酸(PAA)因含有较多极性官能团,可溶于水,而被用作锂电池正负极黏结剂。PAA黏附性好,但极性基团使得分子链间形成的氢键导致PAA链刚性较大,不利于维持充放电过程中极片的完整性,因此,控制PAA官能团数量、改变官能团种类及PAA分子链结构,对锂电池电性能的提高势在必行。本文综述了近几年锂电池用PAA黏结剂的研究进展,重点介绍了PAA黏结剂的结构特性、改性及应用方式及其对不同种锂电池首次库伦效率、循环稳定性和阻抗性能的影响,并对PAA黏结剂的未来改性研究热点做了展望,探索PAA引入不同结构的弹性或导电聚合物后,对于黏结剂本身性能的影响,改善界面性能,以适用于不同活性材料正负极,提高锂离子传输速率,更好地提高锂电池的使用性能。     

Synthesis and blue electroluminescent properties of zinc (II) [2-(2-hydroxyphenyl)benzoxazole]

This study reports on the properties of organic light-emitting diodes (OLEDs) with zinc (II) [2-(2-hydroxyphenyl)benzoxazole] as a hole-blocking layer. OLEDs devices are prepared in a conventional OLEDs structure (i.e., anode/HTL/EL/HBL/cathode and anode/HTL/HBL/EL/cathode). The luminescence efficiencies and the turn-on voltage are significantly affected by the existence of the hole-blocking layer. This is attributed to an excellent hole-blocking property, which is in turn due to the high HOMO energy level (6.5 eV). The device showed luminous efficiency 2.46 lm/W at 5 V. The maximum luminance of about 10,000 cd/m² is obtained, and the turn-on voltage (2.5 V) is affected by the existence of the hole-blocking layer.     

Experimental study of the organic light emitting diode with a p-type silicon anode

We have fabricated and studied an organic light emitting diode (OLED) with a p-type silicon anode and a SiO₂ buffer layer between the anode and the organic layers which emits light from a semitransparent top Yb/Au cathode. The luminance of the OLED is up to 5600 cd/m² at 17 V and 1800 mA/cm², the current efficiency is 0.31 cd/A. Both its luminance and current efficiency are much higher than those of the OLEDs with silicon as the anodes reported previously. The enhancement of the luminance and efficiency can be attributed to an improved balance between the hole- and electron-injection through two efficient ways: 1) restraining the hole-injection by inserting an ultra-thin SiO₂ buffer layer between the Si anode and the organic layers; and 2) enhancing the electron-injection by using a low work function, low optical reflectance and absorption semitransparent Yb/Au cathode.     

“Quasi‐freestanding” Graphene‐on‐Single Walled Carbon Nanotube Electrode for Applications in Organic Light‐emitting Diode

An air‐stable transparent conductive film with “quasi‐freestanding” graphene supported on horizontal single walled carbon nanotubes (SWCNTs) arrays is fabricated. The sheet resistance of graphene films stacked via layer‐by‐layer transfer (LBL) on quartz, and modified by 1‐Pyrenebutyric acid N‐hydroxysuccinimide ester (PBASE), is reduced from 273 Ω/sq to about 76 Ω/sq. The electrical properties are stable to heat treatment (up to 200 ºC) and ambient exposure. Organic light‐emitting diodes (OLEDs) constructed of this carbon anode (T ≈ 89.13% at 550 nm) exhibit ≈88% power efficiency of OLEDs fabricated on an ITO anode (low turn on voltage ≈3.1 eV, high luminance up to ≈29 490 cd/m², current efficiency ≈14.7 cd/A). Most importantly, the entire graphene‐on‐SWCNT hybrid electrodes can be transferred onto plastic (PET) forming a highly‐flexible OLED device, which continues to function without degradation in performance at bending angles >60°.     

Pure color emission in transparent organic light-emitting diodes

The microcavity effect in transparent organic light-emitting diodes (TOLEDs) was investigated according to the structure of an anode and a cathode. Color purity of green TOLEDs could be improved from (0.29, 0.62) to (0.23, 0.68) and the light emission in TOLED could be well manipulated by controlling the microcavity effect in the device. In addition, the total light-emitting efficiency of TOLED in normal direction could be improved by 60% compared with that of conventional devices by using semitransparent metal electrodes both as an anode and a cathode.     

Flexible top-emitting organic light-emitting diodes using semi-transparent multi-metal layers

In this paper, the improved device performance of top-emitting organic light-emitting diodes (TEOLEDs) with a thin multi-metal layer stack of nickel/silver/nickel (Ni/Ag/Ni) and aluminum/silver/aluminum (Al/Ag/Al) that were used as the anode and cathode on a flexible substrate is discussed. In particular, Indium-Tin-Oxide (ITO) as an anode electrode has been used recently even though it has some problems for flexible devices. Therefore we suggested that a thin multi-metal layer electrode as a new anode is fabricated instead of ITO anode. It was verified that the ITO-free TEOLEDs showed an enhanced probability of the recombination of the electrons and holes through an improved electron/hole charge balance. We also analyzed the optical and electrical characteristics using the current density, luminance, luminance efficiency, external quantum efficiency (EQE), CIE x, y coordinates, and EL spectra of flexible TEOLED devices were characterized. ITO-free, flexible, green-emitting OLEDs with a low cost and a simple process were demonstrated.