基于MADN:DPAVBi掺杂体系的蓝光与白光有机发光二极管的研究

发布时间：2018-05-04 10:12

本文选题：有机电致发光 + 掺杂　；参考：《兰州大学》2015年硕士论文

【摘要】：有机发光二极管(Organic light-emitting diodes, OLED)因其具有高效节能、宽视角、快速响应、抗震性好等特点,引起研究领域及商界的广泛关注。白光OLED器件既可以与较为成熟的微电子刻蚀彩色滤色膜技术相结合以获得其它类型的OLED器件,同时在显示和照明领域也具有广泛的应用前景。而蓝光OLED是实现白光的三基色之一,它对实现全彩显示非常重要。虽然OLED经过近二十年的发展,但是目前离商业实用化和大尺寸屏幕还有差距,存在着一些亟待解决的问题,如蓝光材料不成熟、蓝光器件发光亮度和效率低、白光器件随发光时间和偏置电压发生色度改变、寿命短等。针对以上问题本论文主要围绕提高蓝光OLED亮度和效率、改善白光OLED器件色稳定性、提高器件寿命以及增强器件载流子注入效率等做了以下几方面的研究：制造了结构为：ITO(160nm)/m-MTDATA (20 nm)/NPB (30 nm)/MADN: DPAVBi(x wt.%)(15 nm)/BCP(15 nm)/Alq3 (30 nm)/Al(100 nm)的四组蓝光OLED器件。其中DPAVBi的掺杂浓度分别为0、4、6、8wt.%。对四组器件进行对比分析,发现DPAVBi的掺杂浓度不仅能影响器件中的电流密度,还显著影响着器件的发光特性。当掺杂浓度为6wt.%时我们得到亮度为57000 cd/m2,发光效率为47 cd/A的蓝光OLED器件；研究了发光层厚度对器件的影响。改变蓝光发光层的厚度,制造了厚度分别为15、20、25、30 nm的四组蓝光OLED器件,发现随着发光层厚度的增加,器件在波长为495 nm的电致波峰强度也随之增加,经分析我们认为这是微腔结构对器件产生了影响；改变蓝光发光层的顺序,并同时制造了结构为ITO(160 nm)/m-MTDATA(20 nm)/NPB(30 nm)/MADN:DPAVBi(6 wt.%)(15 nm)/MADN:TBPe(5 wt.%)(15 mn)/BCP(15 nm)/Alq3(30 nm)/Al(100 nm)的双蓝光发光层的蓝光OLED对比器件,发现器件在工作状态下,载流子主要在靠近阴极的发光层中复合。我们分析,这是由于空穴的注入效率远高于电子的注入效率所致；另外,我们将P型材料F4-TCNQ掺杂到NPB中形成掺杂的空穴传输层,制造了结构为ITO(160 nm)/m-MTDATA(20 nm)/NPB:F4-TCNQ (1 wt.%)(20 nm)/MADN:DPAVBi(6 wt.%) (15 nm)/BCP(15 nm)/Alq3(30 nm)/Al(100nm)的蓝光OLED器件,发现对NPB进行适当的P型掺杂后,可有效地提高器件的发光效率。另外,我们还将Rubrene掺杂到MADN作为发光层制造了单层发光层的白光OLED器件,由器件的电致发光光谱发现主体材料与掺杂剂Rubrene之间发生了Forster能量转移；将DPAVBi与Rubrene同时掺杂到MADN中作为发光层,制造了双掺杂单层发光层的白光OLED器件,由器件电致发光光谱发现黄光成分远大于蓝光成分。我们分析这是因为电荷优先激发Rubrene发光所致；另外,制造了结构为ITO(160 nm)/m-MTDATA(20 nm)/NPB(30 nm)/MADN:Rubrene(5 wt.%)(5 nm)/MADN:DPAVBi(6 wt.%)(15 nm)/BCP(15 nm)/Alq3(30 nm)/Al(100 nm)的双发光层蓝光器件并改变发光层的顺序制造了两个对比器件,测试结果表明当发光层顺序为MADN:Rubrene/MADN:DPAVBi (由阳极到阴极方向)的白光器件比发光层为MADN:DPAVBi/MADN:Rubrene的器件稳定性好,寿命长。这是因为Rubrene对空穴的陷阱作用很好地平衡及调控了器件中载流子的复合区域；改变黄光发光层的厚度我们成功制备了白光OLED器件,其色坐标CIE为(0.3201,0.3459)。在电极与有机层之间插入缓冲层是一种提高OLED器件发光效率的方法。本论文还初步探索了将金属氧化物半导体NiOx应用到有机发光二极管中对器件的影响。改变NiOx层的厚度制备出四组对比绿光OLED器件。分析得出：插入适当厚度的NiOx缓冲层后器件中空穴的注入效率明显提高,器件的发光效率大大提高。柔性显示是OLED的一个重要特点,也是OLED器件未来的发展趋势。我们在PET柔性衬底上也成功制造了蓝光OLED,研究了空穴阻挡层BCP对该器件的影响,发现空穴阻挡层能够有效地增加空穴在发光层中的输运时间,增大空穴与电子在发光层中的复合几率。最后,论文对器件做了失效分析,讨论了OLED的衰退机制,并且研究了有机层表面平整度对器件寿命的影响,发现有机层表面粗糙的器件会因为表面的凸点在器件工作电压增加时产生大量的焦耳热,导致器件性能的严重衰退,甚至损毁,减少器件的寿命。论文的主要创新点有：(1)以MADN:DPAVBi为掺杂型蓝光发光层,制备了高亮度、高效率的蓝光OLED器件,并研究发光层厚度对蓝光器件性能的影响；(2)制备了双蓝光发光层的蓝光器件,改变蓝光发光层顺序研究其对蓝光OLED器件载流子复合和发光效率的影响；(3)制备了双发光层的白光OLED器件并研究发光层顺序和厚度对白光器件色稳定性和寿命的影响；(4)设计并以电化学方法制备了NiOx为阳极缓冲层的绿光OLED及对比器件,研究了NiOx缓冲层对器件载流子注入效率的影响。该工作尚未见文献报道。
[Abstract]:Organic light-emitting diodes (OLED), which has the characteristics of high efficiency, energy saving, wide angle of view, fast response and good earthquake resistance, has attracted wide attention in the field of research and business. The white light OLED device can be combined with the more mature microelectronic etching color filter film technology to obtain other types of OLED devices. It is also widely used in the field of display and lighting, and blue light OLED is one of the three basic colors to realize the white light. It is very important to realize full color display. Although OLED has been developed for nearly twenty years, there is still a gap between commercial utility and large size screen, and there are some problems to be solved urgently, such as blue light material is not successful. The luminance and efficiency of the blue light devices are low, the white light devices change with the chromaticity of the luminescence time and bias voltage, and the lifetime is short. In this paper, the following aspects are mainly focused on improving the brightness and efficiency of the blue light OLED, improving the color stability of the white light OLED device, improving the life of the device and enhancing the efficiency of the carrier injection. ITO (160nm) /m-MTDATA (20 nm) /NPB (30 nm) /MADN: DPAVBi (x wt.%) (x wt.%) (x wt.%) (15 nm) /BCP (15) /BCP (100) four groups of blue light devices. The current density also significantly affects the luminescence characteristics of the devices. When the doping concentration is 6wt.%, we get a blue light OLED device with a luminance of 57000 cd/m2 and a luminescent efficiency of 47 cd/A. The influence of the thickness of the luminescent layer on the device is studied. The thickness of the blue light layer is changed, and the four groups of blue light OLED devices with a thickness of 15,20,25,30 nm, respectively, are made. It is found that with the increase of the thickness of the luminescent layer, the electric wave peak intensity of the device at the wavelength of 495 nm also increases. By analysis, we think this is the effect of the microcavity structure on the device; the order of the blue light emitting layer is changed, and the structure is ITO (160 nm) /m-MTDATA (20 nm) /NPB (30 nm) /MADN:DPAVBi (6 wt.%) (15 nm) /MADN:TBPe (5) (5). Wt.%) a blue light contrast device of (15 Mn) /BCP (15 nm) /Alq3 (30 nm) /Al (100 nm) with a blue light layer of blue light. It is found that the carrier is mainly in the light layer near the cathode in the working state. We analyze the injection efficiency of the hole far higher than the injection efficiency of the electron; furthermore, we doped the P material F4-TCNQ. The doped hole transmission layer is formed in NPB, and a blue light device with a structure of ITO (160 nm) /m-MTDATA (20 nm) /NPB:F4-TCNQ (1 wt.%) (20 nm) /MADN:DPAVBi (6 wt.%) (15 nm) /BCP (30) /BCP (30) is found. Brene is doped to MADN as a luminescent layer to produce a white light OLED device with a single layer of light emitting layer. The electroluminescent spectrum of the device shows a Forster energy transfer between the main material and the dopant Rubrene, and DPAVBi and Rubrene are doped into MADN as a luminescent layer, and a white light OLED device with a double doped single layer luminescent layer has been produced. The electroluminescence spectra show that the yellow light is far greater than the blue light component. We analyze this due to the charge first excitation of Rubrene luminescence, and the two luminescent layer blue light of ITO (160 nm) /m-MTDATA (20 nm) /NPB (30 nm) /MADN:Rubrene (5 wt.%) (5 nm) /MADN:DPAVBi (6 wt.%) (30 15) Two contrast devices are produced in order to change the sequence of the light emitting layer. The test results show that the devices with MADN:Rubrene/MADN:DPAVBi (from the anode to the cathode) are more stable and longer than the light emitting layer (MADN:DPAVBi/MADN:Rubrene). This is due to the good balance of the hole traps for the Rubrene. The complex region of the carrier in the device is regulated, and the white light OLED device is successfully prepared by changing the thickness of the yellow light emitting layer. The color coordinates CIE is (0.3201,0.3459). The insertion of the buffer layer between the electrode and the organic layer is a method to improve the luminous efficiency of the OLED devices. This paper also preliminarily explored the NiOx of the metal oxide semiconductor. Four groups of contrast green OLED devices are prepared by changing the thickness of the NiOx layer with the thickness of the organic light-emitting diodes. The analysis shows that the injection efficiency of the holes in the device is obviously improved after inserting the appropriate thickness of the NiOx buffer layer, and the efficiency of the device is greatly improved. The flexible display is an important feature of the OLED and the OLED device is not. The development trend. We also successfully manufactured the blue light OLED on the PET flexible substrate, and studied the effect of the hole barrier layer BCP on the device. It is found that the hole barrier layer can effectively increase the transport time of the hole in the luminescent layer and increase the compound probability of the hole and the electron in the luminescent layer. Finally, the paper makes a failure analysis to the device. The decline mechanism of OLED is discussed, and the effect of the surface roughness on the life of the device is studied. It is found that the rough surface of the organic layer will produce a lot of Joule heat on the surface of the device because of the increase of the working voltage of the device, which leads to the serious deterioration of the device performance and even damage and reduce the life of the device. The main innovation of this paper is the main innovation of the paper. There are: (1) the blue light OLED devices with high brightness and high efficiency are prepared with MADN:DPAVBi as the doped blue light emitting layer, and the influence of the thickness of the luminescent layer on the performance of blue light devices is studied. (2) the blue light devices of the double blue light layer are prepared, and the influence of the blue light emitting layer on the carrier recombination and the luminous efficiency of the blue light OLED device is studied. (3) the effect of the order and thickness of the luminescent layer on the color stability and life of the white light devices was studied. (4) the green light OLED and the contrast device of the NiOx as the anode buffer layer were designed and prepared by electrochemical method. The effect of the NiOx buffer layer on the carrier injection efficiency was studied. The work has not been seen yet. Give a report.

【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN383.1

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