Te薄膜封装层对有机电致发光器件寿命的影响

采用Te薄膜封装层作为OLED(organic light emitting diode)器件的保护层,以达到延长器件使用寿命的目的.在高真空(3×10-4Pa)条件下,利用真空蒸镀的方法,在绿光OLED多层器件各功能层蒸镀完成后,又在阴极的外面蒸镀了一层Te薄膜封装层,然后再按一般的方法进行封装.对比了一般封装与增加Te薄膜封装层后器件的性能,封装过程均未加干燥剂.研究发现,未加Te薄膜封装层器件的半衰期为2 880 h,增加Te薄膜封装层后器件的半衰期接近5 800 h.由此可见,Te薄膜封装层的增加将使器件的寿命延长两倍多.并且所增加的Te薄膜封装层基本不影响器件的电流-电压特性、亮度-电压特性、色坐标等光电性能.     

Se薄膜封装层对OLED器件寿命的影响

对于绿光OLED多层器件,在高真空条件下,利用真空蒸镀的方法,在各功能层蒸镀完成后,又在阴极的外面蒸镀了一层硒薄膜封装层,然后再按一般方法进行封装.对比了正常封装与增加Se薄膜封装层后器件的性能,对比实验中封装过程都未加干燥剂.研究发现未加Se薄膜封装层器件的半衰期为2 880 h,增加Se薄膜封装层器件的半衰期接近4 000 h,Se薄膜封装层的增加将器件的寿命延长了1.4倍;研究还发现Se薄膜封装层基本不影响器件的电流-电压特性、色坐标等光电性能.     

MgF2/Se薄膜封装层对OLED性能及寿命的影响

有机电致发光器件(OLEDs)在使用过程中,易受到 空气中水汽、氧气及其它污染物的影响从而导致其工作寿命降低。本文将具有良好光透过率 和热稳定性的MgF₂薄膜与在水汽和氧气中具有良好稳定性的Se薄膜通过真空蒸镀制成复 合薄膜作为OLEDs的封装层,以达到提高器件使用寿命的目的。器件各功能层蒸镀完成后, 保持真空度(3×10－4 Pa)不变,在阴极表面蒸镀MgF₂/Se薄 膜封装层。比较 了绿光OLED器件(器件结构为ITO/CuPc/NPB/Alq₃:C-545T/Alq ₃/LiF/Al)封装前后的亮度-电压-电流密度特性、电致发光光谱及寿命。研究 发现,经过MgF₂/Se封装后,器件的电流密度-电压特性、亮度和发光光谱几乎没 有受到影响,二者的光谱峰都在528 nm处,色坐标(CIE)分别为(0.3555,0.6131)和(0.3560,0.6104),只是起亮电压由3V变为4V;器件的寿命由原来的175h变为300h,提高了1.7倍 。因此,MgF₂/Se薄膜是一种有效的OLEDs无机薄膜封装层。     

聚对二甲苯类薄膜用于有机电致发光器件的封装

采用热解化学气相沉积聚合(TCVDP)方法制备了聚对二甲苯(PPX)和聚一氯对二甲苯(PCPX)薄膜材料,利用其对有机电敛发光器件(OLED)进行了封装.利州紫外可见光谱、扫描电镜(SEM)对薄膜的相关性能进行了表征.比较了器件经过两种薄膜封装前后器件的工作寿命.实验结果表明:利用TCVDP方法,可以制备出透明的表面平整、结构致密的聚对二甲苯类薄膜材料;用于OLED)的封装能大幅度地提高器件的工作寿命,经过PPX封装后的寿命为1215 h,经过PCPX封装后的寿命为1 558 h,比未封装的器件寿命(197 h)提高了6～8倍.     

有机电致发光器件的新型薄膜封装技术研究

针对有机电致发光器件(OLED)在空气中水汽和O2作用下寿命下降的问题,提出一种对OLED进行薄膜封装方法。封装薄膜由电子束蒸镀Al2O3薄膜和原子层沉积(ALD,atomic layer deposition)Al2O3薄膜相结合形成。利用Ca薄膜电学测试方法测定封装薄膜的水汽透过率(WVTR)。具体实现方法是,采用玻璃作为衬底,在100nm的Al电极上蒸镀200nm的Ca膜,然后对整个系统进行薄膜封装,只留出Al电极的一部分作为探针接触电极。实验发现,采用电子束蒸镀结合ALD的Al2O3薄膜封装,Ca薄膜变成透明的时间比未封装或采用单一结构封装得到了延长。为了检验薄膜封装效果,制作了一组绿光OLED,器件结构为ITO/MoOX(5nm)/mMTDATA(20nm)/NPB(30nm)/Alq3(50nm)/LiF(1nm)/Al,实验结果表明,本文提出的薄膜封装方法对器件进行封装,器件的寿命得到了延长。     

有机电致发光器件(OLED)的封装技术研究

有机电致发光显示器(OLED)对水汽和氧气非常敏感,渗入OLED器件内的水汽和氧气会和有机功能层及电极材料发生反应而影响器件寿命。为此,文中根据OLED器件对封装材料的要求,分析了OLED器件封装技术,重点介绍了薄膜封装技术的研究现状。     

有机电致发光器件封装技术的研究进展

有机电致发光显示器件(OLED)被认为是最有潜力的平板显示器件之一.由于OLED具有低驱动电压、高亮度、宽视角及超薄等优点,逐渐成为各国研究的热点.OLED对水分和氧气都非常敏感,进入到器件内部的水分和氧气会严重影响器件的寿命,因而影响OLED的产业化发展.OLED器件的有效封装能延长器件的寿命.综述了玻璃衬底、柔性衬底OLED封装技术的研究现状,以及不同封装的优缺点.     

电场激活压力辅助烧结对(Bi2Te3)0.2(Sb2Te3)0.8热电材料微观结构及热电性能的影响

采用电场激活压力辅助烧结（FAPAS）技术制备了(Bi2Te3)0.2(Sb2Te3)0.8热电材料,采用无电场、低电场强度和高电场强度三种烧结方式作为对比实验,研究了烧结过程中施加电场强度对(Bi2Te3)0.2(Sb2Te3)0.8热电材料微观结构和热电性能的影响。研究结果表明,在烧结过程中施加电场,可明显提高(Bi2Te3)0.2(Sb2Te3)0.8热电材料的电导率和Seebeck系数,从而提高其综合电功率因子;而采用大电场强度烧结则会使(Bi2Te3)0.2(Sb2Te3)0.8材料出现层状结构择优取向,在电性能相对较高的情况下亦使其热导率明显减低,从而获得较高ZT值。     

用ZnS薄膜作为空穴缓冲层的高效率有机发光二极管

用磁控溅射方法制备的ZnS薄膜作为有机发光器件(OLEDs)的空穴缓冲层,使典型结构的 OLEDs(ITO/TPD/Alq/LiF/Al) 的发光性能得到改善.ZnS 缓冲层厚度对器件性能影响的实验结果表明,当ZnS缓冲层厚度为 5 nm 时,器件的亮度增加了2倍多;当ZnS缓冲层厚度为5、10 nm时,器件的发光电流效率增加40%.研究结果表明 ZnS 薄膜是一种好的缓冲层材料,它能够提高器件的发光效率,改善器件的稳定性.     

硅离子注入对Ge2Sb2Te5结构和电阻的影响

采用磁控射频溅射法制备了Ge2Sb2Te5薄膜,利用离子注入法研究了硅掺杂对薄膜结构和电阻性能的影响.研究发现,由于硅的掺杂,Ge2Sb2Te5薄膜的结构不仅保留了原有的面心立方低温晶相和六方高温晶相,而且出现了菱形六面体的Sb2Te3晶相;掺杂硅后,Ge2Sb2Te5薄膜的电阻有较大变化,晶态电阻的提高有利于降低非晶化相变过程的操作电流,薄膜电阻-温度稳定性的改善可保证有较宽的操作电流波动范围.     

有机电致发光器件薄膜封装研究进展

有机电致发光器件(OLEDs)对水汽和氧气非常敏感,渗入OLEDs内的水汽和氧气会腐蚀有机功能层及电极材料,严重影响器件寿命。文中根据OLEDs对封装材料的要求,分析了目前最有前景的OLEDs封装技术———薄膜封装,重点介绍了薄膜封装的分类和研究现状。     

Two-step fabrication of thin film encapsulation using laser assisted chemical vapor deposition and laser assisted plasma enhanced chemical vapor deposition for long-lifetime organic light emitting diodes

A thin film encapsulation layer was fabricated through two-sequential chemical vapor deposition processes for organic light emitting diodes (OLEDs). The fabrication process consists of laser assisted chemical vapor deposition (LACVD) for the first silicon nitride layer and laser assisted plasma enhanced chemical vapor deposition (LAPECVD) for the second silicon nitride layer. While SiN_x thin films fabricated by LAPECVD exhibits remarkable encapsulation characteristics, OLEDs underneath the encapsulation layer risk being damaged during the plasma generation process. In order to prevent damage from the plasma, LACVD was completed prior to the LAPECVD as a buffer layer so that the laser during LACVD did not damage the devices because there was no direct irradiation to the surface. This two-step thin film encapsulation was performed sequentially in one chamber, which reduced the process steps and increased fabrication time. The encapsulation was demonstrated on green phosphorescent OLEDs with I–V-L measurements and a lifetime test. The two-step encapsulation process alleviated the damage on the devices by 19.5% in external quantum efficiency compared to the single layer fabricated by plasma enhanced chemical vapor deposition. The lifetime was increased 3.59 times compared to the device without encapsulation. The composition of the SiNx thin films was analyzed through Fourier-transform infrared spectroscopy (FTIR). While the atomic bond in the layer fabricated by LACVD was too weak to be used in encapsulation, the layer fabricated by the two-step encapsulation did not reveal a Si–O bonding peak but did show a Si–N peak with strong atomic bonding.     

Investigation on the atomic layer deposition of the Se doped Sb–Te phase change films using an alkyl-silyl precursor

We used TDMASb, Te(t-Bu)₂, and Se(SiMe₃)₂ as precursors to investigate the behavior of atomic vapor deposition (AVD) during formation of Se doped Sb–Te phase change films. The deposition was prepared by a sequential recipe for the atomic layer deposition (ALD) reaction with consideration of the electrostatic interactions between the Se alkyl-silyl precursor and the Sb and Te precursors. The Sb–Te–Se ternary films could be deposited by AVD at temperatures of 80–300 °C with fine controllability and high surface quality. The elemental composition of the films was controlled by varying the deposition temperature. The Se doping effect on the crystallization temperature and set resistance in the crystalline state was evaluated via electrical measurements and theoretical analyses by applying the glass transition temperature model and resonance bonding model. The results indicated that the incorporation of Se into Sb–Te films may provide for improved thermal stability and power consumption efficiency in phase-change random access memory (PCRAM) devices.     

Determination of the Origin of Crystal Orientation for Nanocrystalline Bismuth Telluride-Based Thin Films Prepared by Use of the Flash Evaporation Method

We have investigated the origin of crystal orientation for nanocrystalline bismuth telluride-based thin films. Thin films of p-type bismuth telluride antimony (Bi–Te–Sb) and n-type bismuth telluride selenide (Bi–Te–Se) were fabricated by a flash evaporation method, with exactly the same deposition conditions except for the elemental composition of the starting powders. For p-type Bi–Te–Sb thin films the main x-ray diffraction (XRD) peaks were from the c-axis (Σ{00l}/Σ{hkl} = 0.88) whereas n-type Bi–Te–Se thin films were randomly oriented (Σ{00l}/Σ{hkl} = 0.40). Crystal orientation, crystallinity, and crystallite size were improved for both types of thin film by sintering. For p-type Bi–Te–Sb thin films, especially, high-quality structures were obtained compared with those of n-type Bi–Te–Se thin films. We also estimated the thermoelectric properties of the as-grown and sintered thin films. The power factor was enhanced by sintering; maximum values were 34.9 μW/cm K² for p-type Bi–Te–Sb thin films at a sintering temperature of 300°C and 23.9 μW/cm K² for n-type Bi–Te–Se thin films at a sintering temperature of 350°C. The exact mechanisms of film growth are not yet clear but we deduce the crystal orientation originates from the size of nano-clusters generated on the tungsten boat during flash evaporation.     

Laboratory Thin-Film Encapsulation of Air-Sensitive Organic Semiconductor Devices

We present an approach, which is compatible with both glass and polymer substrates, to in-laboratory handling and intra-laboratory shipping of air-sensitive organic semiconductors. Encapsulation approaches are presented using polymer/ceramic and polymer/metal thin-film barriers using commercially available materials and generally available laboratory equipment. A technique for depositing an opaque vapor barrier, a transparent vapor barrier, and an approach to storing and shipping air-sensitive thin-film organic semiconductor devices on both polymer and glass substrates are presented. Barrier performance in air was tested using organic light-emitting diodes (OLEDs) as test devices. The half-life performance of OLEDs on plastic substrates in air exceeded 700 h, and that on glass exceeded 500 h. Commercially available heat-seal barrier bag systems for device shipping and storage in air were tested using a thin film of metallic calcium to test water permeation. More than four months of storage of a metallic calcium film in a heat-sealed foil bag was demonstrated in the best storage system. These approaches allow for the encapsulation of samples for longer duration testing and transportation than otherwise possible.     

Effects of Sb-doping on the grain growth of CIGS thin films fabricated by electrodeposition

Cu(InGa)Se2 (CIGS) solar cells become one of the most important thin film photovoltaic devices thus far. The doping of Sb has improved the grain size of CIGS thin film and therefore led to the enhancement of solar cell efficiency. Various approaches have been used for the Sb doping. Not many reports of electrodeposition of In, Ga and Sb alloy have been reported. In this work, the Sb thin film was coated over Cu film surface prior to the In and Ga deposition in order to form a Cu/Sb/In/Ga metal precursor. After selenization, the Sb doped CIGS film was prepared. The structure and morphology of Sb doped CIGS films were investigated compared with the undoped CIGS reference samples. A modified selenization method was proposed, which improved the grain size. Finally, the conversion efficiency of Sb doped CIGS based solar cells has been improved by 1.02%.     

空穴阻挡层对有机发光二极管寿命的影响

为研究空穴阻挡层对有机发光二极管寿命的影响,制备了含有空穴阻挡层的典型双层结构有机发光二极管,其中八羟基喹啉铝(Alq3)为发光层和电子传输层,BCP 为空穴阻挡层.器件的寿命随着发光层的厚度减小而降低,实验结果表明积累在发光层的空穴和激子可能是影响器件寿命的主要原因之一.     

Lifetime improvement of organic light-emitting diodes with a butterfly wing's scale-like nanostructure as a flexible encapsulation layer

Biomimetic nanostructures like butterfly wing's scale were fabricated with an anodic aluminum oxide (AAO) nanoimprint lithography technique. This bio-inspiration nanostructure exhibits an intrinsic hydrophobic property and thus was applied as a flexible encapsulation layer in organic light-emitting diodes (OLEDs) to improve device's lifetime. A ∼80% enhancement on lifetime was obtained with simply imprinting the biomimetic nanostructures onto the flexible substrates. Our work provides a simple encapsulation approach for OLEDs, especially for flexible OLEDs.     

Depth profiling organic light-emitting devices by gas-cluster ion beam sputtering and X-ray photoelectron spectroscopy

The composition depth profile in organic light-emitting devices (OLEDs) is investigated using X-ray photoelectron spectroscopy (XPS) coupled with gas-cluster Ar-ion beam milling (Ar-GCIB). The XPS technique gives precise information about the surface chemistry of the organic thin films and is capable of differentiating the various charge transport, host and guest materials used in an OLED. The use of large Ar ion clusters (∼1500–2500 atoms/cluster) in the milling process allows for small amounts of the organic thin film to be sputtered away without contaminating the surface or damaging the underlying material chemistry. By probing OLEDs as a function of depth, key parameters including emissive layer composition and interface quality can be assessed directly. It is found that the depth profile for graded-composition emissive layer OLEDs closely matches the intended deposition profiles, maintaining both the composition gradient and the intended endpoint compositions. The ability to resolve and correlate subtle changes in film composition to variations in device performance will help inform efforts in device design, while also serving as a diagnostic tool to better understand the mechanisms for device degradation and failure.