【作者】 夏虹；

【导师】 马於光；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2006， 博士

【摘要】 重金属配合物的应用大大提高了有机电致发光器件的效率,但由于磷光材料具有较长的激发态寿命,为避免激发态的淬灭,常将其掺入主体材料中。要求主体材料有较好的载流子传输性质、良好的成膜性和热稳定性,但我们认为主-客体之间的关系在本质上决定了电致磷光器件性能的优劣,并且目前较少地被研究。本论文选择高发光效率、电化学可逆的钌配合物作为磷光客体,不同类型的有机/聚合物材料作为主体,研究了影响主-客体匹配的因素和及对器件性能的影响。主要工作包括以下三方面:第一,分别使用传输性能不同的三种蓝光材料PVK、PBD和PF作为主体,并比较电致发光性能差异。结果显示空穴传输为主的PVK是更适合的主体,电子传输为主的PBD是不适合的。这是由于Ru(dpp)配合物特殊的电化学行为决定的,电子传输材料作为主体时一个Ru(dpp)配合物的分子可能捕获多个电子,与空穴结合时,会发生载流子无效复合。而空穴传输主体不会出现这种情况。以PF作为主体时,主-客体之间化学相容性不好,存在较严重的聚集,器件性能较差。第二,为方便地获得载流子传输性能不同的主体,采用电子和空穴传输材料的混合物作为主体,通过调节两种材料比例调节主体的传输性能。选择PVK和PBD的混合物作为Ru(dpp)和Ru(dbeb)2+的主体,调节PBD的比例,当其为40 %时,混合物的载流子传输性质与Ru(dpp)的电化学行为匹配的最好;器件性能最佳。同时也尝试了小分子混合作为主体,其器件性能优于单一小分子主体的器件性能。第三,为避免聚合物自身的缺陷,选择可旋涂的芴齐聚物TCPC和THPH作为主体,电化学数据和单载流子传输器件证明TCPC比THPH具有更强的空穴注入和传输能力。因此TCPC作为主体的发光层内具有相对较多的空穴,这有利于载流子的有效再结合,Ru(dpp): TCPC表现出更高的电致磷光性能。此外以TCPC作为Irppq的主体的红光器件和以TCPC同时作为主体的白光器件都获得较好的器件性能,这说明TCPC是较为优良的主体材料。更多还原

【Abstract】 In passed decades, major breakthroughs have led to significant improvements inthe performance of organic light-emitting devices due to the use of phosphorescentheavy metal complexes. The triplet-triplet annihilation and triplet-polaronannihilation is occurred at high concentration of triplet state exciton, which is due tolong triplet exciton life of phosphorescent materials. Incorporatingelectrophosphorescent metal complexes into the host organic/polymer materials is aneffective way to resolve this problem. Generally, the compounds with aryl groups,for example phenyl and carbazole, were selected as host materials. The host materialshave to have good carrier transfer ability, wide energy bandgap, good film capability,high glass transformation temperature, longer exciton life, etc. While guest-hostrelationship also affects performance of electrophosphorescent devices. In this thesis,high efficient phosphorescent guests and organic/polymer hosts of different typeswere selected, and we studied factors affecting matching of guest and host andresolve these problems. In Chapter 2, The Ru(II) complex Ru(dpp) with good stability, highphosphorescent efficiency and reversible electrochemistry behavior was selected asguest, three blue light-emitting materials with different carrier transfer ability wereselected as hosts. The Cyclic voltammogram curve of Ru(dpp) shows that Ru(dpp)molecules have four reversible redox processes, i.e. three electroreduction processesand one electrooxidation process. The electrochemical properties of Ru(dpp)molecule, which reflects the carrier trapping ability of host, may be a basic designcriterion for the selection of polymer matrix and device configuration. When ann-type polymer PBD was used as host, the excess electrons were trapped soon bythree reduction states of Ru complex site, radiationless deactivation of high energyexcited states is bad, so the device performance was poor. Whereas the hole transfermaterial was used as host and a hole block layer was inserted, the probability ofmulti-electron trapping at the Ru(dpp) site is reduced, thus the efficiency of deviceswere effectively increased. The devices with Ru(dpp)-PVK blend as light-emittinglayer could achieve higher luminous efficiency up to 8.6 cd/A. The deviceperformance with PF of more-balanced charge transporting ability as host was bad,due to phase separation of host and guest.In Chapter 3, the blend of electron transporting material and hole transportingmaterial was selected as host to easily adjust charge carrier transporting ability ofhost. The blend of PVK and PBD was selected as host for Ru(dpp) guest. Theadjusting content of PBD in the host, the device performance is best at PBDconcentration of 40 %, the luminous efficiency reached 5.71 cd/A with simple devicestructure, which is remarkably higher than efficiency of devices with only PVK orPBD as host. Further, for Ru(dbeb)2+ guest the blend of PVK-PBD (40 %) was stillselected as host to fabricate devices. The adjusting concentration of guest, theexternal quantum efficiency reached 3.0 cd/A with simple device structure, and purered colour emitted. While the blend of small molecular hole transporting materialCBP and PBD was selected as host for Ru(dpp) to fabricate devices, and the deviceperformance is remarkably higher than devices with only CBP or PBD as host.In Chapter 4, to avoid phase separation of components in blend and defects ofself-polymer, the oligomer TCPC and THPH were selected as hosts for Ru(dpp) withspiting-coating method to fabricate devices, and device performance of Ru(dpp):TCPC is better. The Electrochemistry data and single charge carrier transportingdevices proved that hole inject and transfer of TCPC is stronger which of THPH, soin light-emitting layer of devices with TCPC as host the hole carrier is more, whichis favorable for efficient recombination of charge carriers. The luminous efficiency ofRu(dpp): TCPC devices reached 2.13 cd/A. when the TCPC is host for Ir(ppq) theluminous efficiency is 1.30 cd/A with simple device structure. When TCPC is hostand blue material doped green and red phosphorescent dyes the white light devicesreached maximum brightness of 2367 cd/m2 and efficiency of 1.53 cd/A. Theseresults proved that TCPC is good host material.更多还原