银表面等离子体增强有机电致发光特性研究

发布时间：2018-05-26 02:26

本文选题：有机电致发光 + 导电薄膜　；参考：《聊城大学》2015年硕士论文

【摘要】：有机电致发光器件被广泛应用于照明、平板显示等行业,由于有机电致发光器件具有亮度高,功率效率高,自主发光,全固态易弯曲,可视角大等优点,具有广泛的应用前景。有机电致发光器件对制备环境要求极为苛刻,极容易在空气中被氧化从而寿命受到影响。高效率的发光器件需要高功函数高透明度的阳极,高效的空穴,电子传输材料以及高效的发光材料。本文深入研究有机电致发光器件的发光机理,针对目前有机发光器件中面临的主要问题:高功函数透明阳极,载流子注入不平衡,发光层发光效率低等,提出解决方案。首先,有机电致发光器件对阳极的要求极为严格,必须同时具备高透过率,高电导,高功函数,表面平整度好。基于这点我们设计了Zn O/metal/Zn O多层膜机构来制备实验所需的透明导电薄膜。实验表明:当Zn O厚度为21.6nm,中间金属Au的厚度为6nm时,薄膜的导电率为6.89×10-4?·cm,可见光范围内透过率达80%以上,表面粗糙度为Rs=1.4nm,完全满足有机电致发光器件的要求。运用统计学原理和量子力学原理对膜系的导电机理进行分析,提出了它的电阻率模型。最后同实验结果进行比较,发现理论模拟和实验结果符合较好。有机材料空穴迁移率一般比电子迁移率大两个数量级以上,这使得器件发光层中载流子浓度不平衡,造成载流子的浪费,严重影响器件的发光效率和性能。针对此问题,本文通过使用银铝共掺硫化锌作为电子传输材料来提高电子迁移率。通过理论计算发现,当共掺硫化锌厚度为4.4nm时具有较好的电子传输性能。实验结果表明,当共掺硫化锌厚度为8nm时,器件的发光强度和相对外量子效率较没有电子传输层的器件分别提高了430倍和130倍。同时我们制备了以高效电子传输材料TPBi为电子传输层的发光器件。对比发光强度和外量子效率发现,银铝共掺硫化锌作为电子传输层具有更高的电子迁移率,使得器件中载流子浓度趋于平衡,因而具有更高的发光强度与发光效率。当光照射金属表面及具有纳米微结构的金属时会产生表面等离子体共振现象,此过程往往伴随着能量转移。在有机电致发光器件中引入金属纳米颗粒可以诱发新的能量转移途径,从而打破荧光效率仅有25%的限制。本文通过控制有机材料的蒸镀速率,使其表面形成具有均匀的纳米微孔,再在其表面慢速率的蒸镀金属银填充有机物纳米微孔,形成金属银纳米颗粒。实验表明:由于金属银纳米颗粒的引入,使得器件的发光强度提高了5.5倍,相对外量子效率较没有金属纳米颗粒的器件有明显的提升。器件的荧光瞬态寿命谱表明,银纳米颗粒的引入,使得发光材料的寿命从11.68ns提高到13.10ns。荧光寿命的延长说明银纳米颗粒的引入使得器件中出现了新的能量转移途径,降低了激子非辐射弛豫过程中的能量损失。
[Abstract]:Organic electroluminescent devices (OLEDs) are widely used in lighting, flat panel display and other industries. Due to the advantages of high luminance, high power efficiency, independent luminescence, easy bending of all solid state and large viewing angle, organic electroluminescent devices have a wide application prospect. Organic electroluminescent devices (OLEDs) require extremely harsh preparation environment and are easily oxidized in air and thus their lifetime is affected. High efficiency luminescent devices require high power function, high transparency anode, high efficiency hole, electron transport material and high efficiency luminescent material. In this paper, the luminescence mechanism of organic electroluminescent devices (OLEDs) is deeply studied, and a solution is put forward to solve the main problems in OLEDs, such as transparent anode with high power function, unbalanced carrier injection and low luminous efficiency. First of all, organic electroluminescent devices must have high transmittance, high conductivity, high power function and good surface smoothness. Based on this, a Zn O/metal/Zn O multilayer mechanism is designed to prepare transparent conductive thin films for experiments. The experimental results show that when the thickness of Zn O is 21.6 nm and the thickness of intermediate metal au is 6nm, the conductivity of the film is 6.89 脳 10 ~ (-4) cm, the transmittance is over 80% in the visible range, and the surface roughness is 1.4 nm, which fully meets the requirements of organic electroluminescent devices. The electrical conduction mechanism of the film system is analyzed by using the principle of statistics and quantum mechanics, and its resistivity model is proposed. Finally, compared with the experimental results, it is found that the theoretical simulation is in good agreement with the experimental results. The hole mobility of organic materials is generally more than two orders of magnitude higher than that of electron mobility, which makes the carrier concentration in the luminous layer unbalance, resulting in a waste of carriers, which seriously affects the luminescence efficiency and performance of the device. In order to improve the electron mobility, the silver aluminum co-doped zinc sulfide is used as the electron transport material. Through theoretical calculation, it is found that when the thickness of co-doped zinc sulfide is 4.4nm, it has better electron transport performance. The experimental results show that when the thickness of co-doped zinc sulfide is 8nm, the luminescence intensity and the relative external quantum efficiency of the device are 430 and 130 times higher than those of the device without electron transport layer, respectively. At the same time, we have fabricated the light-emitting devices with the high efficiency electron transport material TPBi as the electron transport layer. Compared with the luminescence intensity and quantum efficiency it is found that the silver aluminum co-doped zinc sulfide as the electron transport layer has higher electron mobility which makes the carrier concentration in the device tend to balance so that it has higher luminescence intensity and luminescence efficiency. Surface plasmon resonance (SPR) occurs when the light shines on the metal surface and the metal with nanoscale structure, which is often accompanied by energy transfer. The introduction of metal nanoparticles in organic electroluminescent devices can induce new energy transfer pathways, thus breaking the limit of only 25% fluorescence efficiency. In this paper, by controlling the evaporation rate of organic materials, a uniform nanometer micropore is formed on the surface of organic materials, and then the slow rate evaporation silver plating on the surface of organic materials is filled with organic nano-micropores to form metallic silver nanoparticles. The experimental results show that the luminescence intensity of the device is increased 5.5 times because of the introduction of silver nanoparticles, and the quantum efficiency of the device is obviously improved compared with that of the device without metal nanoparticles. The fluorescence transient lifetime spectra show that the lifetime of the luminescent material increases from 11.68ns to 13.10nswith the introduction of silver nanoparticles. The prolongation of fluorescence lifetime indicates that the introduction of silver nanoparticles leads to a new energy transfer pathway and reduces the energy loss in the exciton nonradiative relaxation process.
【学位授予单位】：聊城大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN383.1

【共引文献】