【作者】 张晓；

【导师】 樊健；

【作者基本信息】 苏州大学 ， 化学， 2022， 硕士

【摘要】 近年来,有机发光二极管(Organic Light-Emitting device,OLED)凭借自发光、色彩饱和、响应时间短等优点已逐步实现商业化。热活化延迟荧光(Thermally Activated Delayed Fluorescence,TADF)材料被称为第三代OLED发光材料,理论上实现了 100%激子的利用。此外,TADF材料成本低廉,是极具发展前景的发光材料。TADF材料在蓝光和绿光方面已经取得了优异的研究成果,红光TADF材料的研究仍需实现重大的突破。红光TADF分子由强的给体单元和强的受体单元组成,形成强的分子内电荷转移,促使发光波长红移。由于氰基的强拉电子特性,基于氰基的受体单元常用作构成红光TADF的拉电子部分,而给体单元种类繁多,其中以三苯胺作给体的红光TADF分子均取得了较为优异的成果。于是本文致力于开发基于不同N-杂环给体单元的红光TADF材料,研究其光物理性质,热稳定性,电化学性质和电致发光性质,为后面红光TADF材料的研究提供新的思路。1、第二章研究了基于N-杂环螺环吖啶给体单元的红光TADF分子的设计合成及电致发光性能。基于10H-螺[吖啶-9,9’-芴]给体单元,设计合成了四个红光TADF分子 BPCN-spAc,FBPCN-spAc,DBQ-spAc 和 DBPz-spAc。四个 TADF 分子均实现了小的 ΔEST,反系间窜越速率(The rate constant of reverse intersystem crossing process,kRISC)高达106 s-1。最重要的是,四个化合物在固态薄膜中的荧光量子产率(Photoluminescence Quantum Yield,PLQY)均在 90.0%以上。四个器件的最大外量子效率(External Quantum Efficiency,EQE)均大于 20%。其中,BPCN-spAc的OLED器件发光在592 nm,外量子效率接近30%,最大电流效率和功率效率分别为 70 cd/A 和 82.68 lm/W,CIE 坐标(0.55,0.45)。2、第三章研究了基于N-杂环咔唑给体单元的红光TADF分子的设计合成及电致发光性能。基于多个咔唑单元作给体,与强拉电子受体单元结合,合成并纯化出了 4Cz-2CN,4Cz-2N和2Cz2Ph-2CN三个新型红光TADF分子。多个给体的TADF分子会形成电荷共振型混合三重态,有利于分子的反系间窜越过程。扭曲的分子结构也会抑制分子的振动弛豫,减少激子淬灭。毫无意外的,三个TADF分子均具有较小的ΔEST。研究其电致发光器件性能发现2Cz2Ph-2CN分子的发光性能最优,器件外量子效率为14.64%,CIE坐标为(0.59,0.41)。3、第四章研究了基于N-杂环桥连三苯胺给体单元的红光TADF分子的设计合成及电致发光性能。将两个氧原子引入到三苯胺结构中,设计合成了给体单元桥连三苯胺(BOP),与苊结构的受体组合设计合成了 APDC-BOP,AQDC-BOP和TFQ-BOP三个D-A型红光TADF分子。以APDC-BOP为发光客体的器件显示了6.95%的器件效率,发光波长为652 nm,CIE是(0.64,0.35)。更多还原

【Abstract】 In recent years,organic light-emitting devices(OLEDs)have been gradually commercial due to their advantages of self-luminescence,color saturation,and short response time.Thermally activated delayed fluorescence(TADF)materials have been known as the third-generation OLED light-emitting materials,which can realize the utilization of 100%excitons theoretically.In addition,TADF materials is easily available and cheap,which is a promising luminescent material.At present,TADF materials have achieved excellent results in blue and green emission.Research on red TADF materials still needs to achieve breakthroughs.The red TADF molecule is composed of a strong donor unit and a strong acceptor unit,forming a strong intramolecular charge transfer,which promotes the red shift of the emission wavelength.Due to the strong electron-withdrawing properties of cyano groups,cyano-based acceptor units often constitute red-light TADF molecules.Compared with acceptor units,there are many types of donor units.For example,red light TADF molecules with triphenylamine as the donor have achieved excellent results.Therefore,this paper mainly studies red TADF materials based on different N-heterocyclic donor units including their photophysical properties,thermal stability,electrochemical properties,and electroluminescence properties.1.The second chapter studies the design,synthesis and electroluminescence properties of red TADF materials based on N-heterocyclic spiro acridine donor units.Based on the 10H-spiro[acridine-9,9’-fluorene]donor unit,four red TADFs,BPCN-spAc,FBPCN-spAc,DBQ-spAc and DBPz-spAc,were designed and synthesized.All four TADFs achieved small ΔEST by designing and kRISC as high as 106 s-1.Most importantly,the fluorescence quantum yields(PLQYs)of the four emitters in solid-state thin films were all above 90.0%.The maximum external quantum efficiency(EQE)of the four devices were higher than 20%.Among them,the OLED device of BPCN-spAc emits at 592 nm,the external quantum efficiency was close to 30%,the maximum current efficiency and power efficiency were 70 cd/A and 82.68 lm/W,respectively,with CIE coordinates(0.55,0.45).2.The third chapter studies the design,synthesis and electroluminescence properties of red TADF materials based on N-heterocyclic carbazole donor units.Based on multiple carbazole units as donor and combined with strong electron acceptor units,three new red TADFs,4Cz-2CN,4Cz-2N and 2Cz2Ph-2CN,were synthesized and purified.The TADF molecules with multiple donors generally form chargeresonance-type hybrid triplet states,which is beneficial to the RISC process.The twisted structure also suppresses vibrational relaxation,reducing exciton quenching.Not surprisingly,all three TADFs have smaller ΔESTs.The luminescence performance of the 2Cz2Ph-2CN was the best,the external quantum efficiency of the device was 14.64%,and the CIE coordinates was(0.59,0.41).3.The fourth chapter studies the design,synthesis and electroluminescence properties of red TADF materials based on N-heterocyclic bridged triphenylamine donor units.The bridged triphenylamine(BOP)of donor unit was designed and synthesized by introducing two oxygen atoms into the triphenylamine structure.Three red TADFs based on donor-acceptor(D-A)type,APDC-BOP,AQDC-BOP and TFQ-BOP,were designed and synthesized by combining donor BOP with acceptor acenaphthene.The device with APDC-BOP as the luminescent guest showed a device efficiency of 6.95%at 653 nm and CIE of(0.64,0.35).更多还原