【作者】 牛霞；

【导师】 华玉林；

【作者基本信息】 天津理工大学 ， 凝聚态物理， 2006， 硕士

【摘要】 有机电致发光显示器件（OLED）作为一种新型的固体平板化显示器件,凭借着驱动电压低,效率高,可柔性化等优势和广阔的市场应用前景,成为近年来发展十分迅速的显示技术。其中白光OLED器件涵盖整个可见光区的红、绿、蓝三种基色,可以很容易地获得全彩色显示器件,同时还可以作为液晶背光源和固态照明光源使用。因此,白光OLED的研究具有非常重要的科学意义和使用价值。本文以制备和研究结构简单的OLED为工作重点,并以提高器件中蓝光成分为主要工作。简单介绍了OLED的发展历程,并重点介绍了白光OLED的研究进展和实际应用的意义,以及器件的发光原理和影响发光性能的主要因素。首次尝试将聚合物和小分子材料相结合,采用旋涂的方法形成发光层,简化器件制备工艺,同时两者的结合可以进行优势互补,充分提高器件的整体性能。首先对本实验选用的新型有机小分子蓝光材料TBPe,进行了简单的性能分析,并通过与其结构相似的蓝光材料的对比,表明其对掺杂浓度的要求相对较低,同时也分析了其与聚合物混合制备器件的可行性。制备了结构为:ITO/白色发光层/BCP/Alq3/Mg:Ag的单一发光层白光OLED。通过多组实验对比,最终确定了最佳染料掺杂浓度和结构的器件,最佳色坐标为（0.33,0.38）,十分接近白色等能点,且不随外加驱动电压的变化而显著变化。为了进一步提高器件的发光性能,考虑到不同有机材料所适用的不同制备方法,我们依照传统的制作工艺,制备了以PVK:TBPe为蓝色发光层和Alq₃:rubrene为橙黄色发光层的双层白光器件。通过适当调节发光层的掺杂比例和厚度,得到了发光性能比较理想的白光器件。我们还尝试将本身可以发绿白光,且兼具电子传输特性的材料Zn（BTZ）2替代Alq3作发光层的母体材料。器件的启亮电压下降到6V左右,最大亮度达到1300cd/m2,最大外量子效率为0.31%,最佳色坐标为（0.32,0.36）。通过对比发现,双层器件的各项光电性能均比单层器件有明显提高,我们根据有机材料的能级结构和能量传输理论,结合OLED的发光机理和能量传输原理,初步分析了双层器件的发光过程,以及性能提高的根本原因在于合理地选择材料和设计器件结构。最后我们选择了另一种蓝光材料NPB和空穴阻挡材料BCP,将电子和空穴的复合区域限制在空穴传输层中,分别制备了蓝色和橙红色发光器件。通过合理设计器件结构和调节发光层厚度,使两种发光以恰当比例相混合,制备了一种新型的白光器件,结构为:ITO/PVK:MEH-PPV/NPB/BCP/Alq₃/Mg:Ag。器件在5V左右启亮,而且随着外加电压的变化,色坐标从（0.32,0.31）变为（0.33,0.29）,均在白色发光区之内,器件的最大亮度为2320cd/m²,最大外量子效率为0.52%。通过合理地选择高效的发光材料和试验条件的改善,提高发光层的质量,完善器件结构,器件的发光性能有望大幅提高,这也是我们下一步工作的重点。更多还原

【Abstract】 Organic light-emitting devices (OLEDs) have been achieving much attention because of their ideal characteristics for industry, such as solid state display, active emitting, broad visual angle, high efficiency, availability for flexible and full color display, etc. Nowadays, white OLEDs can be used as backlights for liquid crystal displays, illumination light sources and even full color displays combined with color filters. In spite of having nice efficiency, many OLEDs are fabricated with complicated process. Thus, they are not adapted to the need of large-scale commercial manufacture. So in this paper we manage to study and produce the simple structure device with high efficiency.Firstly, we introduced the characteristic of TBPe, which is a new kind of blue material. Then we fabricated the single emitting layer OLED whose configuration is ITO/white emitting layer/BCP/Alq3/Mg:Ag. By adjusting the adulterated proportion and the configuration of the device properly, a white OLED with Commission Internationale de l’Eclairage (CIE) coordinates of (0.33, 0.38) was generated. The CIE coordinate stayed virtually constant when the voltage increased from 8 to 16 V. The maximum brightness of the device was 553cd/m2, and the maximum external efficiency was 0.16%.In order to get higher efficient device using TBPe, we tried to make it as following structure: ITO/PVK:TBPe/Alq3:rubrene/Mg:Ag. Then the device had a white-light emission whose CIE coordinates was (0.26, 0.33). Furthermore, we attempted to use Zn(BTZ)2 instead of Alq3 as electron transport material. The device had a very low starting voltage at 6V. Bright white light, over 1300cd/ m2, was successfully obtained by controling the thickness of each emitting layer and the adulterated proportion of dopant accurately. The maximum exteral quantum efficiency reached 0.31% at 8V. The CIE coordinates of the white OLED was(0.32,0.36), which constantly located in the white-light region with changing voltage. In a word, the performance of the whole device was increased remarkably due to its suitable structure and dye material.At last, we chose another organic material—NPB as main blue light emitting component. The configuration of the device is ITO/PVK:MEH-PPV/NPB/BCP/Alq3/Mg:Ag, using BCP as hole blocking layer. After perfecting the device, the corresponding brightness and efficiency were 2320cd/m2 and 0.52%, respectively. The light emission, which is nearly to pure white, changed from (0.32,0.31) to (0.33,0.29) with the increasing driven voltage.In the whole paper, we tried to blend the polymer and small molecule organic material together as light emitting layer, which make up the shortcoming for each other. The efficiency of white light-emitting is improved only by designing the device structure and changing the electron transport material reasonably. We also discussed the emitting mechanisms of the material and the devices.更多还原