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类型 基础研究 预答辩日期 2018-01-23
开始(开题)日期 2016-03-03 论文结束日期 2017-12-05
地点 东南大学九龙湖校区化学化工学院小会议室319 论文选题来源 973、863项目     论文字数 5.3 (万字)
题目 湿法热活化延迟荧光材料的设计合成及器件研究
主题词 有机发光二极管,热活化延迟荧光材料,湿法加工,热交联,树状物
摘要 湿法有机发光二极管(OLEDs)因其制备工艺简单,成本低和易于实现大规模生产的特点越来越受到人们的关注。作为第三代发光材料,热活化延迟荧光(TADF)材料可以在无贵金属的条件下实现100%的内量子效率,得到了科研工作者的广泛研究。目前,高效的TADF器件大多采用真空蒸镀方法制备,湿法制备的TADF器件的报道非常少并且主要采用主客体掺杂的方式。然而,这些掺杂体系存在相稳定性差、加工工艺复杂和重现性差等缺点。分子设计上的限制使得开发具有较小?EST,同时又可湿法制备的TADF材料变得十分困难。因此,开发可以用于非掺杂湿法器件制作的高效TADF发光材料是十分必要的。本论文利用聚合物材料和树枝状材料的湿法加工的优势,结合高效的TADF发光单元,设计合成了一系列新型可湿法TADF发光材料,主要从减少三线态浓度淬灭,提高材料的发光性能,平衡载流子的传输,降低驱动电压等方面进行了一些探索。 1、分别设计并合成了含有交联基团的基于二苯砜的TADF蓝光客体材料和咔唑类主体材料。通过调节主客体分子的掺杂比例,采用原位热交联方法,首次合成了一系列新型蓝光聚合物发光层薄膜。研究表明,发光层具有良好的热稳定性,成膜性和抗溶剂侵蚀性,适用于湿法制备OLED器件。器件性能显示,基于聚合物P9的湿法器件的发射峰为444 nm,最大外量子效率为2%。可交联TADF材料的应用为实现高效的非掺杂蓝光湿法器件提出了新的设计思路。 2、通过对发光核和外围树枝基团的设计,合成了两个基于三嗪的黄光树枝状TADF分子,表征了其热力学、光学和电化学性质。研究表明,苯环的引入可有效地增加发光核的电子供体与受体之间的距离从而降低分子?EST并增强荧光量子产率。通过非共轭烷基链引入外围树枝基团,可有效地封装分子的发光核抑制三线态的浓度猝灭,并且维持TADF核的光学性质不变。结果显示,以该TADF分子作为发光层制备的非掺杂湿法OLED,最大外量子效率达到11.8%,器件性能属于目前报道的最佳湿法非掺杂荧光器件性能范畴。 3、通过对高效红光TADF分子的结构修饰,同时在分子外围引入树枝基团,首次报道了三个基于蒽醌的近红外光树枝状TADF分子。甲氧基基团的供电子共轭效应增加了发光核的共轭程度使得发射波长红移。双极传输型树枝的引入不仅能够有效地封装分子的发光核抑制三线态的浓度猝灭,而且能够平衡器件中的载流子传输,从而实现高性能的湿法器件。器件性能显示,MPPA-MCBP的非掺杂湿法器件的发射峰为698 nm,最大亮度为377 cd m-2,最大外量子效率达到0.624%,说明通过外围树枝调控均衡载流子传输性能是提高湿法器件电致发光性能的有效途径。 4、采用非共轭连接方式将常用激基复合物的空穴单元引入到TADF核的外围,设计合成了两个双功能化树枝状TADF分子。同时,采用对应的电子单元作为电子传输层,使得树枝状分子在器件中同时具有TADF和激基复合物的功能。通过这样的分子设计,能够有效的解决采用高三线态树枝基团带来的高起亮电压的问题。器件性能显示,基于G-mCP的非掺杂湿法器件的起亮电压仅为2.7 eV,最大外量子效率为16.5%,最大功率效率为46.6 lm W-1,器件性能属于目前报道的最佳湿法荧光器件性能范畴。
英文题目 SYNTHESIS AND ELECTRO-OPTICAL PROPERTY INVESTIGATION OF THERMALLY ACTIVATED DELAYED FLUORESCENCE MATERIALS USED FOR SOLUTION-PROCESSED OLEDs
英文主题词 organic light-emitting diodes, thermally activated delayed fluorescence, solution-process, thermally cross-linkable materials, dendrimer
英文摘要 Solution-processed organic light-emitting diodes (OLEDs) have attracted great attention as a device for application in large-size OLEDs because of simple fabrication process, low-cost manufacturing technology and easy scalability of the solution process. As critical component of OLEDs, pure organic fluorescence materials with thermally activated delayed fluorescence (TADF) that can realize 100% internal quantum efficiency are regarded as promising materials for the third generation of OLEDs. Although TADF OLEDs can approach 100% internal quantum efficiency, the excited state quenching induced by the triplet-triplet annihilation should be minimized by utilizing the host-guest systems to achieve highly efficient electroluminance. However, a host-guest system is normally composed of two/multi-component mixtures, which makes solution-based process challenging derives from inevitable phase separation. In this work, to address this issue, a series of novel TADF materials, which forms with polymers and dendrimers, was developed to be an alternative strategy to restrain the concentration quenching, improve the luminous efficiency, balance the carrier transporting and reduce the operating voltage. The main content of this dissertation is as follows: 1. We designed and synthesized two thermally cross-linkable materials, DV-CDBP and DV-MOC-DPS, which act as a host material and a TADF emitter for solution-processed OLEDs, respectively. Utilizing the method of in-situ crosslink, the cross-linked films with the different mass ratios of V-CDBP and DV-MOC-DPS were investigated. The cross-linked films possess excellent thermal, morphological stabilities and corrosion-resistance. Employing the cross-linked film as emitting layers, an efficient blue solution-processed OLED with a maximum external quantum efficiency of 2.0% was achieved. The molecular design reported here provides a novel route toward highly efficient solution-processed OLEDs. 2. We synthesized two high efficient TADF dendrimers based on the orientation of molecular design and the utilization of peripheral dendrons. Introduced the phenyl bridge to increase the distance of the emission core TA between donor (D) and acceptor (A) is a promising route to simultaneously achieve small singlet-triplet energy splitting (?EST) and enhanced PL quantumyields (PLQYs). Furthermore, non-conjugated aliphatic chains carbazole/tricarbazole dendrons were conveniently introduced to the TADF core, which can effective encapsulate the emission core to restrain the concentration quenching effect and make the fluorescence of the core independent. By utilizing the emitter as the non-doped solution-processed emissive layers, the resulting yellow OLED achieved low driving voltage of 2.4 V and superior external quantum efficiency of 11.8%, which is comparable to the most-efficient nondoped solution-processed fluorescent OLED. 3. Three near-infrared (NIR) dendrimers with TADF characteristics are reported to develop the non-doped solution-processed OLED for the first time. We select the well-known red TADF molecule as principal ingredients because of their excellent performances for OLED application. Introducing the methoxy substituents for the enhanced electron-donating ability and the longer conjugation length owing to the existence of lone-pair electrons. Thus, the modified core with the characteristic of TADF and the emission of NIR can be anticipated. The rigid ring end-capped aliphatic chain dendrons are introduced to improve the dissolvability and film-forming ability. Simultaneously, the functional dendrons can encapsulate the core to prevent concentration quenching and render balanced charge transportation. Employing MPPA-MCBP as the emitter, the non-doped solution-processed device exhibits a maximum external quantum efficiency (EQE) of 0.62% with a peak wavelength at 698 nm, which is comparable to the most-efficient solution-processed NIR FOLEDs with similar electroluminescent spectra, which indicates that the molecular modification is very cost-effective and competitive for improving the device performance. 4. As we know, the utilization of exciplex-forming has been considerd as an idea strategy for realizing the power-efficient OLEDs. With this idea in mind, two bifunctional TADF dendrimers have been designed and synthesized. Non-conjugated connection can make the photophysical properties of TADF core and the exciplex-forming function of dendrons independent. With the utilization of the hole-transporting dendrons and the adjacent electron-transporting layer recombination for the formation of the interfacial exciplex, ensures efficient charge injection and transporting and efficient singlet and triplet energy transfers from the interfacial exciplex to the TADF core. Consequently, the nondoped device of G-mCP achieves extremely low driving voltage of 2.7 V and a high power efficiency of 46.6 lm W-1, which is among the highest power efficiency of the reported TADF s-OLED.
学术讨论
主办单位时间地点报告人报告主题
研究生院 2014.10.19 四牌楼校区致知堂 徐静娟 界面组装与生物传感
化学化工学院孙岳明课题组 2014.12.13 化学化工楼319会议室 孙开涌 蓝色磷光及Self-host型铱类配合物的发展近况
化学化工学院孙岳明课题组 2015.06.29 化学化工楼319会议室 孙开涌 Highly Efficient Near-Infrared Organic Light-Emitting Diode
化学化工学院 2015.12.8 九龙湖宾馆至友厅 许蕾 高效异质结构复合光催化材料的制备与应用
化学化工学院 2015.12.9 九龙湖宾馆至友厅 祁争健 有序荧光超薄膜的自组装及其氧传感的研究
化学化工学院孙岳明课题组 2016.3.11 化学化工楼319会议室 孙开涌 Highly Efficient Near-Infrared Delayed Fluorescence Organic Light Emitting Diodes Using a Phenanthrene-Based Charge-Transfer Compound
化学化工学院孙岳明课题组 2017.4.26 化学化工楼319会议室 孙开涌 High-Performance Green OLEDs Using Thermally Activated Delayed Fluorescence with a Power Efficiency of over 100 lm W?1
化学化工学院 2017.11.9 九龙湖纪忠楼308 孙元胜 多维共聚焦荧光成像技术FLIM/PLIM/FCS/STED及应用
     
学术会议
会议名称时间地点本人报告本人报告题目
南京工业大学 2015.10.14-2015.10.18 江苏省南京市希尔顿大酒店 Novel aggregation-induced emission and thermally activated delayed fluorescence materials based on thianthrene-9,9’,10,10’-tetraoxide derivatives
太原理工大学 2017.12.6-2017.12.10 山西省太原市湖滨大酒店 Design strategy of yellow thermally activated delayed fluorescent dendrimers for highly efficient non-doped solution-processed OLEDs.
International Association of Advanced Materials (IAAM) 2017.3.11-2017.3.16 Singapore Princess Cruise Self-host thermally activated delayed fluorescent dendrimers with flexible chains: an effective strategy for non-doped electroluminescent device based on solution processing
     
代表作
论文名称
CBP derivatives dendronized self-host TADF dendrimer: Achieving efficient non-doped near-infrared or
Near-infrared thermally activated delayed fluorescent dendrimers for the efficient non-doped solutio
Highly efficient and color tunable thermally activated delayed fluorescent emitters and their applic
Design strategy of yellow thermally activated delayed fluorescent dendrimers and their highly effici
Thermally cross-linkable thermally activated delayed fluorescent materials for efficient blue soluti
Novel aggregation-induced emission and thermally activated delayed fluorescence materials based on t
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
丁维平 正高 教授 博导 南京大学
姚成 正高 教授 博导 南京工业大学
周建成 正高 教授 博导 东南大学
林保平 正高 教授 博导 东南大学
范以宁 正高 博导 南京大学
      
答辩秘书信息
姓名职称工作单位备注
王育乔 副高 副教授 东南大学