【作者】 陈浩；

【导师】 赵祖金；

【作者基本信息】 华南理工大学 ， 材料科学与工程， 2022， 硕士

【摘要】 有机发光二极管（Organic Light-Emitting Diode,OLED）具有自发光、高效率、低成本、轻薄柔性、快速响应等优点,不仅成为科研界竞相研究的热点,在产业届也得到了飞速发展,目前已经逐步走进人们的日常生活之中。OLED技术的普及和应用,离不开高效发光材料的研发。近些年报道的热活化延迟荧光（Thermally Activated Delayed Fluorescence,TADF）材料凭借其100%激子利用率和纯有机的优势成为科研界的新宠,然而传统TADF材料面临的聚集发光猝灭和效率滚降等问题,限制了其进一步发展。在本论文中,我们基于羰基开发了一系列聚集诱导延迟荧光（Aggregation-Induced Delayed Fluorescence,AIDF）材料,它们在非掺和掺杂器件中都表现出优异的电致发光效率和较低的效率滚降。此外,我们还进一步探究了这类延迟荧光材料在作为敏化主体材料时的性能,开发出了高性能的白光OLED器件（WOLED）和敏化OLED器件。具体研究内容如下:在第二章工作中我们基于羰基设计了两个新的AIDF分子CDBP-BP-PXZ和CDBP-BP-DMAC,它们具有典型的聚集诱导发光（Aggregation-Induced Emission,AIE）和TADF特性,在四氢呋喃（THF）溶液中几乎不发光,但是在蒸镀沉积的薄膜中有强烈的延迟荧光发射。两个分子都具有良好的热稳定性、高的荧光量子产率、极小的单三线态能级差(ΔE_ST)和双极传输能力。以CDBP-BP-PXZ和CDBP-BP-DMAC为发光层制备的非掺杂器件的外量子效率分别为15.5%和9.5%,掺杂器件的外量子效率分别为20.8%和16.8%。更重要的是,它们在1000 cd m^-2的高亮度下都表现出优异的光谱稳定性和非常小的效率滚降,充分表明它们在制备高效稳定的OLED器件中具有非常好的应用潜力。在第三章工作中我们设计了一个以羰基为吸电子核、以弱给电子基团SFAC和主体材料DCB为电子给体的新天蓝色延迟荧光分子DCB-BP-SFAC。DCB-BP-SFAC具有明显的聚集增强发光（Aggregation-Enhanced Emission,AEE）和TADF的特性,且具有较高的三线态能级和优异的双极传输能力。DCB-BP-SFAC在非掺杂薄膜中表现出强的天蓝光发射,不仅可以用来构筑高性能天蓝光非掺杂和掺杂OLED器件,还可以作为绿光、橙光和红光材料的高效主体。为了进一步拓展DCB-BP-SFAC的应用,成功制备了荧-磷杂化单发光层WOLED器件和全荧光单发光层WOLED器件,其电致发光效率分别达到了17.8%和19.1%,在1000 cd m^-2亮度下的显色指数（Color Render Index,CRI）分别为77.3和56.7。在第四章工作中,我们在以上课题的基础上设计并合成了一个新的延迟荧光分子SBF-BP-SFAC,它表现出典型的AEE和TADF特性,具有良好的热稳定性、双载流子传输能力、优异的发光效率和高的水平偶极取向等性质。SBF-BP-SFAC本身作为一种高效的绿光分子,制备的非掺杂和掺杂OLED器件的外量子效率达到了23.1%和30.6%。SBF-BP-SFAC同样可以作为橙色的荧光、磷光和延迟荧光客体分子的高效敏化剂,制备的三元敏化OLED器件的外量子效率分别达到了13.6%、30.3%和24.2%。基于发光层中从SBF-BP-SFAC到客体发光分子的超快能量传递速率和高效的能量传递效率,降低了三线态激子浓度从而减少浓度猝灭效应,因此这些敏化器件在高亮度下都表现出很小的效率滚降。这些结果充分表明SBF-BP-SFAC无论作为发光材料还是敏化剂,在OLED器件中都具有巨大的应用潜力。更多还原

【Abstract】 Organic light-emitting diode（OLED）possesses the advantages of self-luminescence,high efficiency,low cost,light,flexible,fast response,and so forth.It has not only become a hot topic in the scientific research,but also developed rapidly in the industry and entered people’s daily life gradually.In recent years,the popular thermally activated delayed fluorescence（TADF）materials have become a new favorite in the scientific field because of its 100%exciton utilization and the advantage of purely organic component.However,the problems of aggregation-induced luminescence quenching and large roll-off faced by traditional TADF materials have restricted their further development.In this paper,we develop a series of novel aggregation-induced delayed fluorescence（AIDF）materials,which exhibit excellent electroluminescence efficiency and low efficiency roll-off in nondoped and doped devices.In addition,we further explore the application of these delayed fluorescence materials as host and sensitizer to fabricate efficient doped OLED and white OLED（WOLED）.The research contents are as follows:In the second chapter,we design two novel AIDF molecules（CDBP-BP-PXZ and CDBP-BP-DMAC）with typical aggregation-induced emission（AIE）and TADF properties,which emited weakly in tetrahydrofuran（THF）solution but strongly in films.Both molecules possess excellent properties such as good thermal stability,high photoluminescence quantum yield(Φ_PL),extremely smallΔE_ST（the energy gap between the lowest excited triplet state and the lowest excited singlet state）values and balanced carrier transport ability.The external quantum efficiencies(η_exts)of OLED devices fabricated with CDBP-BP-PXZ and CDBP-BP-DMAC as emitting layers are 15.5%and 9.5%for nondoped devices and 20.8%and 16.8%for doped devices,respectively.More importantly,these devices exhibit excellent emission spectral stability and very small efficiency roll-off at 1000 cd m^-2,demonstrating the great application potential in the fabrication of highly efficient and stable OLEDs.In the third chapter,we design a new delayed fluorescence material DCB-BP-SFAC,using carbonly as electron acceptor and DCB and SFAC as weak electron donors.DCB-BP-SFAC exhibits obvious aggregation-enhanced luminescence（AEE）and TADF properties,as well as a high triplet energy level and excellent bipolar carrier transport capability.DCB-BP-SFAC radiate strong sky-blue emission in the nondoped film,which could not only be used to fabricate high-performance sky-blue OLED devices,but also serve as efficient hosts for green,orange,and red materials.In order to further explore the application of DCB-BP-SFAC,a fluorescence-phosphorescence hybrid WOLED device and an all-fluorescence WOLED device with single-emissive layer are successfully prepared,and theirη_exts reached 17.8%and 19.1%,respectively.In the fourth chapter,we design and synthesize a new delayed fluorescent molecule SBF-BP-SFAC,which exhibit typical AEE and TADF properties,good thermal stability,bipolar carrier transport ability,excellentΦ_PL and high optical outcoupling efficiency(η_out).Nondoped and doped OLEDs with SBF-BP-SFAC as emitter radiate intense cyan light and outstandingη_exts of up to 23.1% and 30.6%.SBF-BP-SFAC can also function as efficient sensitizer for orange fluorescence material,phosphorescenc material as well as TADF emitter with outstandingη_exts of 13.6%,30.3%and 24.2%,respectively,and small efficiency roll-offs.The fast F（?）rster energy transfer rates and high FET efficiency are achieved in these sensitized OLEDs with SBF-BP-SFAC as sensitizer.The outstanding electroluminance performance demonstrate the great potential of SBF-BP-SFAC as emitter and sensitizer.更多还原