双偶极主体材料的设计、合成及电致发光性质

发布时间：2019-06-18 22:08

【摘要】：磷光有机电致发光器件(PhOLEDs)和延迟荧光电致发光器件(TADF-OLED)由于能100%地利用单重态和三重态激子,相比传统荧光器件具有突出的效率优势而成为OLED领域的研究热点。典型的PhOLEDs和TADF-OLED均采用主客体材料掺杂的器件结构,占发光层主要成份的主体材料对器件综合性能起到了决定性作用,因此主体材料与发光材料同等重要。研究证明,双偶极主体材料能有效平衡正负载流子传输,不仅有助于提高OLED器件的发光效率,还能有效减缓效率衰减。然而,目前双偶极主体材料种类有限,分子设计尚无成熟的方法和理论,尤其其中具有电子传输功能的n-型基团的选择以及与p-型基团的匹配等方面更是挑战。本文针对这一领域现状,通过调节n-型基团的种类、比例、连接方式等因素,设计、制备“单n-型”和“双n-型”两个类型、共五个系列主体材料,并用于制备高效的PhOLEDs和TADF-OLEDs,研究它们的结构-性质-电致发光性能之间的关系,具体如下：(1)含氰基(CN)的“单n-型”主体材料：以CN取代苯基作为电子传输基团,以苯基咔唑作为空穴传输基团,制备o-CzCN、m-CzCN和p-CzCN三种主体材料,通过变换咔唑与中心核邻、间、对的连接方式,成功调节分子的三重态能级和载流子传输能力。其中,以m-CzCN为主体材料、以FIrpic为掺杂客体材料的蓝色磷光器件最大电流效率达到了46.81 cd A-1(最大外量子效率23.14%)；以o-CzCN为主体材料掺杂2CzPN的蓝色延迟荧光器件最大外量子效率达到了14.98%,高于当时2CzPN的文献最高值13.6%。(2)含吡唑的“单n-型”主体材料：以吡唑为n-型基团、以咔唑为p-型基团,同时调节邻间对取代位置以及n-型和p-型基团的摩尔比例,设计、制备了高三重态能级的系列双偶极主体材料o-CzDPz、m-CzDPz、3-CzDPz和mCPDPz,分别应用于蓝色和绿色PhOLEDs和TADF-OLEDs.发现n/p基团摩尔比为2：1最有利于电荷平衡,且间位取代的m-CzDPz为主体材料的蓝色PhOLED和3-CzDPz为主体材料的绿色PhOLED分别获得了26.8%和29.0%高外量子效率。更有意义的是,该系列主体材料的绿色TADF-OLEDs效率滚降极低。(3)含氰基吡啶的“双n-型”主体材料：以氰基吡啶为“双n-型”基团,引入到传统主体材料mCP骨架的苯环或咔唑环上,分别获得新主体材料m-PyCNmCP和3-PyCNmCP,并将它们应用于绿色PhOLEDs中,分别获得了2.01 V和2.27 V的启亮电压(对应于1cd m-2的亮度)和101.4 lm W-1和119.3 lm W-1的功率效率。启亮电压都低于以Ir(ppy)3为客体材料的绿光器件的最低理论电压2.4 V,且2.01 V接近迄今Ir(ppy)3器件的最低启亮电压1.97 V。(4)含毗唑吡啶的“双n-型”主体材料：以吡唑吡啶为“双n-型”电子传输基团,制备双偶极主体材料o-CzPyPz、m-CzPyPz和p-CzPyPz,通过改变分子邻间对的连接方式,调节分子的三重态能量和电荷传输能力等性质。以m-CzPyPz为主体材料的蓝色磷光器件获得了49.1 cd A-’(24.5%)的最大效率和低的效率滚降；以p-CzPyPz为主体材料的绿色磷光器件获得了91.8 cd A-1(27.3%)的最大效率。以m-CzPyPz和p-CzPyPz为主体材料的蓝橙二元白光器件分别获得了57.8 cd A-1(23.6%)和60.7 cd A-1(23.1%)的效率。(5)含二苯膦酰基吡啶的“双n-型”主体材料：以二苯膦酰基取代的吡啶为“双n-型”基团,引入到mCP骨架的不同位置,制备两种双偶极主体材料w-PyPOmCP和p-PyPOmCP。与只含吡啶的参比分子PymCP以及文献上将n-型基团连接在p-型基团上相比,采用二苯膦酰基和吡啶为“双n-型”基团,并将“双n-型”基团直接连接,不仅有效降低分子的LUMO能级,同时也保证了较高的HOMO能级,因而同时促进正负载流子的注入和传输。以m-PyPOmCP为主体材料的蓝色磷光器件的最大效率为55.6 cdA-1(25.3%),以p-PyPOmCP为主体材料的绿色磷光器件的最大效率为98.2 cd A-1(28.2%)。
[Abstract]:The phosphorescent organic electroluminescent device (PhOLEDs) and the delayed fluorescent electroluminescent device (TADF-OLED) have become a hot spot in the field of OLEDs due to the fact that the singlet state and the triplet exciton can be used 100% compared to the conventional fluorescent device. The typical PhOLEDs and TADF-OLEDs adopt the device structure doped with the main guest material, and the main material of the main component of the light-emitting layer plays a decisive role in the comprehensive performance of the device, so that the main material and the light-emitting material are of equal importance. The research has shown that the dual-dipole body material can effectively balance the positive and negative carrier transmission, not only can improve the light-emitting efficiency of the OLED device, but also effectively reduce the efficiency attenuation. However, there are no mature methods and theories for molecular design, especially the choice of n-type groups with electron transport function and the matching with p-type groups. In view of the current situation in this field, two types of "single n-type" and "double-n-type" are prepared by adjusting the type, proportion, and connection mode of n-type group, and five series of main body materials are prepared and used for preparing high-efficiency PhOLEDs and TADF-OLEDs. The relationship between the structure and the properties of the cyano (CN) is studied, in particular the following: (1) a cyano (CN)-containing "single n-type" host material: a CN-substituted phenyl group as an electron transport group, and a phenyl disulfide as a hole transport group to prepare three main body materials of o-CzCN, m-CzCN and p-CzCN, The triplet energy level and the carrier transport capacity of the molecule are successfully adjusted by transforming the connection mode between the IGRP and the central core o, m and the pair. in which, the maximum current efficiency of the blue phosphorescent device is 46.81cd A-1 (the maximum external quantum efficiency is 23.14%) with the m-CzCN as the main material, and the maximum external quantum efficiency of the blue delayed fluorescent device doped with the o-CzCN as the main material is 14.98%, Higher than 2CzPN at that time, the highest value was 13.6%. (2) a single n-type "main material with a high triplet state: a series of double-dipole main body materials o-CzDPz, m-CzDPz, 3-CzDPz and mCPDPz are applied to blue and green PhOLEDs and TADF-OLEDs, respectively. It is found that the molar ratio of n/ p groups is 2:1, which is most favorable for charge balance, and the m-CzDPz of m-CzDPz as the main material and the green PhOLEDs of 3-CzDPz as the main material obtain 26.8% and 29.0% high external quantum efficiency, respectively. More particularly, the green TADF-OLEDs of this series of host materials have a low efficiency roll-off. (3) the "double-n-type" main material containing the cyanamide is introduced into a benzene ring or a benzene ring of the mCP framework of the traditional host material by taking the cyanoacrylate as a "double-n-type" group, and the new main body materials m-PyCNmCP and 3-PyCNmCP are respectively obtained, and are applied to the green PhOLEDs, The power efficiency of the starting voltage of 2.01 V and 2.27 V (corresponding to the luminance of 1 cd m-2) and the power efficiency of 101.4 lm W-1 and 119.3 lm W-1 were obtained, respectively. The light-on voltage is lower than the lowest theoretical voltage of the green device with Ir (ppy)3 as the guest material, and 2.01 V is close to the lowest light-on voltage of the Ir (ppy)3 device to date 1.97 V. (4) The "double-n-type"-body material containing the vivacizumab as the "double-n-type" electron transport group, The bi-polar body materials o-CzPyPz, m-CzPyPz and p-CzPyPz are prepared, and the properties of the triplet energy and the charge transport capacity of the molecules are adjusted by changing the connection mode of the pairs of the molecules. The maximum efficiency and low efficiency roll-off of 49.1 cd A-'(24.5%) were obtained with the blue phosphorescent device of m-CzPyPz as the main material. The maximum efficiency of 91.8 cd A-1 (27.3%) was obtained with the green phosphorescent device of p-CzPyPz as the main material. The efficiency of 57.8 cd A-1 (23.6%) and 60.7 cd A-1 (23.1%) was obtained with m-CzPyPz and p-CzPyPz as the main material. (5) The main material of the "double-n-type" main body with the dibenzo-phenyl-base is the "double-n-type" group, which is introduced into different positions of the mCP framework, and the two dipole body materials w-PyPOmCP and p-PyPOmCP are prepared. Compared with the reference molecule PymCP containing only the same, and the n-type group is connected to the p-type group, the double-n-type "group is adopted, and the double-n-type" group is directly connected, so that not only the LUMO energy level of the molecule is effectively reduced, but also the higher HOMO energy level is ensured, Thereby simultaneously promoting the injection and transmission of positive and negative carriers. The maximum efficiency of the blue phosphorescent device with m-PyPOmCP as the main material is 55.6 cA-1 (25.3%), and the maximum efficiency of the green phosphorescent device with p-PyPOmCP as the main material is 98.2 cd A-1 (28.2%).
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ422;TN383.1

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