基于咪唑的蓝色荧光材料的设计合成与光电性能研究

发布时间：2018-08-29 18:45

【摘要】：有机电致发光技术作为新一代显示技术,近些年来受到广泛关注,经过科研工作者和企业研发的不懈努力,已进入初步产业化阶段。在平面显示方面,有机电致发光器件(OLEDs)因其特有的优势在应用上凸显出很强的竞争力,但作为显示三基色(蓝、绿、红)之一的蓝光器件在性能上仍与其它两个光色有一定差距。尤其是可作为高质量显示的深蓝光器件的发展始终未能取得实质性突破,无论是在器件效率还是寿命方面都不能令人满意。目前蓝光器件存在的主要问题有:效率不够高、光色不理想、在高亮度下的效率衰减相对严重,因此,本文主要针对以上问题进行研究。在分子设计方面,我们选择具有双极性传输潜力的咪唑环作为核心,衍生出菲并咪唑和芘并咪唑两种高效蓝光构筑基团,通过合理的分子设计调节材料的激发态性质,以获得更高的发光效率和更加饱和的发光颜色。在电致发光器件方面,通过系统的结构优化实现最大化的器件性能,并根据各材料在器件中的表现来更加深入地了解其光电性质。除研究这些材料在常规非掺杂和掺杂器件中的光电性能外,我们还尝试性地采用具有相似分子结构的材料构成主-客体系,这种独特的体系展现出了比常规体系更加优秀的器件性能,为最终能实现稳定高效的蓝光OLED提供了新的思路。本文主要包含四部分内容:1.对一系列经典的用于OLED制备的功能材料进行基本光物理和电化学性质表征,从中选择适合用于蓝光器件制备的材料。优化器件的载流子注入结构,改进器件制备工艺,为下面获得高性能蓝光OLED做准备。2.以二苯并噻吩为中心桥,在其3,6-位桥连两个菲并咪唑基团,构成双枝菲并咪唑衍生物,再通过改变中心硫原子的氧化态来调节中心桥的电子密度,合成出两个激发态性质不同的分子。它们在OLED应用中表现良好,并在二者构成的主-客体系的掺杂器件中展现出了略优于常规掺杂体系的器件性能。3.细致探究蒽和芘取代的菲并咪唑和芘并咪唑衍生物的电致发光性能,通过观察器件光电特性曲线的行为,可以推断出这些材料都具备TTA性质,其中PIMPy的非掺杂器件表现出纯蓝发射,CIE坐标(0.154,0.140),在300~3000 cd cm~(-2)的亮度区间内的外量子效率维持在5~5.11%。利用PIMPy为主体,Py IPy为客体,制备的掺杂器件的最大亮度超过了100000cd cm~(-2),最大外量子效率达到7.13%,且亮度超过100 cd cm~(-2)时可保持大于5%的外量子效率。4.设计并合成了萘取代的菲并咪唑和芘并咪唑高效深蓝光材料,并表现出非常平衡的载流子传输性质。两个材料的非掺杂OLED均表现出稳定的深蓝光发射和极弱的效率滚降,利用PIMNA作为主体,Py INA作为客体,制备的掺杂器件最大外量子效率达到5.05%,CIE色坐标为(0.156,0.060),最大亮度13600 cd cm~(-2),同时效率相对稳定,在1000 cd cm~(-2)的亮度下外量子效率为4.67%,这在已报道的CIE坐标接近EBU的标准蓝光的器件中,处于国际领先水平。
[Abstract]:Organic electroluminescent devices (OLEDs), as a new generation of display technology, have attracted wide attention in recent years. Through the unremitting efforts of scientific researchers and enterprises, they have entered the initial stage of industrialization. In the aspect of flat display, organic electroluminescent devices (OLEDs) have shown strong competitiveness in application because of their unique advantages, but as a display three. One of the basic colors (blue, green, red) is still far from the other two in terms of performance. Especially, the development of dark blue light devices which can be used as high-quality displays has not made a substantial breakthrough, both in terms of device efficiency and lifetime are unsatisfactory. In the aspect of molecular design, we choose the imidazole ring with bipolar transmission potential as the core, and derive two high-efficiency blue-light building groups, phenamidazole and pyrene imidazole, through reasonable molecular design. In order to obtain higher luminous efficiency and more saturated color, the excited state properties of the materials are adjusted. In electroluminescent devices, the device performance is maximized by systematic structural optimization, and the photoelectric properties are further understood according to the performance of the materials in the devices. In addition to the optoelectronic properties of doped devices, we also attempt to use materials with similar molecular structures to form host-guest systems. This unique system exhibits better device performance than conventional systems, providing a new idea for achieving stable and efficient blue-light OLED. A series of classical functional materials for OLED fabrication are characterized by their basic photophysical and electrochemical properties, from which materials suitable for the preparation of blue light devices are selected. Carrier injection structure of devices is optimized, and the fabrication process is improved to prepare for the following high performance blue light OLED. 2. Dibenzothiophene is used as the central bridge and its 3,6-position bridge is used. Two molecules with different properties of excited states were synthesized by changing the oxidation state of central sulfur atom to adjust the electron density of the central bridge. They performed well in OLED applications and showed slightly superior performance in host-guest doping devices. The electroluminescent properties of anthracene and pyrene substituted phenamidazole and pyrene substituted phenamidazole derivatives were investigated in detail. By observing the behavior of the photoelectric characteristic curves, the TTA properties of these materials were deduced. Among them, the PIMPy non-doped devices exhibited pure blue emission, CIE coordinates (0.154, 0.140), 300-3000 cd. The external quantum efficiency of the doped device is maintained at 5-5.11% in the luminance range of cm~(-2). Using PIMPy as the main body and Py IPy as the object, the maximum luminance of the doped device exceeds 100 000 CD cm~(-2), the maximum external quantum efficiency is 7.13%, and the external quantum efficiency can be maintained at more than 5% when the luminance exceeds 100 CD cm~(-2). 4. Naphthalene substituted phenanthrene is designed and synthesized. Imidazole and pyrene-imidazole high-efficiency dark blue light-emitting materials exhibit very balanced carrier transport properties. Undoped OLEDs of both materials exhibit stable deep blue light emission and very weak efficiency roll-off. Using PIMNA as the host and Py-INA as the guest, the maximum external quantum efficiency of doped devices is 5.05% and the CIE color coordinate is (0.156). The external quantum efficiency is 4.67% at the brightness of 1000 CD cm ~(-2), which is in the leading position in the world among the reported devices whose CIE coordinates are close to EBU standard blue light.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ422

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