【作者】 刘春雨；

【导师】 刘迪；

【作者基本信息】 大连理工大学 ， 有机化学， 2025， 硕士

【摘要】 随着信息显示技术的发展,OLED显示技术正因其在高清显示领域具有强大应用潜力而得到日益广泛的应用。目前商业化蓝光器件工作过程中需要的稳定性仍只能由传统荧光材料提供,虽然磷光材料和TADF材料已经历了多年研发,但其分子不稳定性导致仍无法满足蓝光材料商业化稳定性的要求。近年来,通过探索多重共振热活化延迟荧光（MR-TADF）材料和热激子（HE）材料,OLED研究取得了重要突破。热激子机制的反系间窜越（RISC）过程是高能三重态（T_n,n≥2）与单重态（S_m,m≥1）之间,将这一机制引入OLED材料设计显著提升了激子利用率。而针对传统TADF材料存在的发射光谱半峰宽较宽、色纯度较低等问题,研究人员创新性地将多重共振效应引入TADF分子设计,开发出MR-TADF材料。该设计将电子给体和电子受体嵌入刚性芳香骨架中,实现了窄发射光谱和高色纯度。基于此,本论文提出了一系列改进策略,并利用相应策略设计合成了一系列高效的HE材料和MR-TADF材料,具体内容如下:（1）本策略提出了一种基于十字形蓝色热激子材料的设计,这种独特的十字形分子架构通过其特征性的"臂状"结构,对高位三重态（T_m,m≤5）和低位单重态（S₁）能级的调控。从水平方向引入了具有给电子特性的1-苯基-1H-苯并二咪唑（PI）和三苯胺（TPA）基团可调控分子给电子能力及局域激发（LE）特性,在垂直方向上,通过引入两种不同吸电子特性的基团[1,1’:4’,1’’-三联苯]-4,4’’-二氰基（DCN）和[1,1’:4’,1’’-三联苯]（TP）,对分子电荷转移（CT）进行调控。这两种材料在非掺杂薄膜中具有出色的光致发光量子产率（PLQY）分别为51.3%和46.5%,制备的非掺杂OLED器件外量子效率（EQE）分别达到7.3%和6.4%展现了出色的性能指标。并且在高亮下仍能保持很低的效率滚降。（2）传统分子设计策略通将螺环单元作为外围组分（如侧链、末端基团或连接单元）使用。而本策略地将刚性9,9’-螺二芴（SF）单元全嵌入或半嵌入到硼/氮多重共振（B/N-MR）发光核中,成功开发出四种具有异构化特性的多重共振热活化延迟荧光（MR-TADF）材料（SF-BN1、SF-BN2、SF-BN3、SF-BN4）。在甲苯溶液中半峰宽（FWHM）仅为15～21 nm,基于掺杂膜的光致发光量子产率（PLQY）高达90%。基于SF-BN1的OLED实现了29.0%的外量子效率（EQE）,其CIE色坐标（0.13,0.08）完全符合BT.2020蓝光标准;并且SF-BN3的天蓝光OLED不仅实现18 nm的超窄半峰宽和29.8%的EQE,其超荧光（HF）器件更将效率进一步提升至35.5%。更多还原

【Abstract】 With the rapid development of information display technology,OLED display technology is gaining increasingly widespread applications due to its strong potential in high-definition displays.Currently,the stability required for commercial blue-light devices can only be provided by traditional fluorescent materials.Despite years of research and development on phosphorescent materials and thermally activated delayed fluorescence（TADF）materials,their molecular instability still prevents them from meeting the stability requirements for commercial blue-light applications.Recent breakthroughs in OLED research have been achieved through the exploration of multiple-resonance thermally activated delayed fluorescence（MR-TADF）materials and hot exciton（HE）materials.The hot exciton mechanism involves reverse intersystem crossing（RISC）processes between high-energy triplet states（T_n,n≥2）and singlet states（S_m,m≥1）.Incorporating this mechanism into OLED material design has significantly improved exciton utilization efficiency.To address the issues of broad emission spectra and low color purity in conventional TADF materials,researchers have innovatively introduced multiple-resonance effects into TADF molecular design,leading to the development of MR-TADF materials.This design embeds both electron donors and acceptors within a rigid aromatic framework,achieving narrow emission spectra and high color purity.Based on these advancements,this study proposes a series of improved strategies and has successfully designed and synthesized several highly efficient hot exciton materials and MR-TADF materials.The main achievements are as follows:（1）We developed a novel design strategy for cross-shaped blue hot exciton（HE）materials.This unique molecular architecture utilizes characteristic"arm-like"structures to precisely modulate high-lying triplet states（T_m,m≤5）and the lowest singlet state（S₁）.Horizontally,electron-donating groups including 1-phenyl-1H-benzo[d]imidazole（PI）and triphenylamine（TPA）were introduced to regulate molecular donor capability and localized excitation（LE）characteristics.Vertically,two distinct electron-withdrawing groups-[1,1’:4’,1’’-terphenyl]-4,4’’-dicarbonitrile（DCN）and[1,1’:4’,1’’-terphenyl]（TP）-were incorporated to control charge transfer（CT）properties.These materials demonstrated outstanding photoluminescence quantum yields（PLQYs）of 51.3%and 46.5%in non-doped films,respectively.The corresponding non-doped OLED devices achieved external quantum efficiencies（EQEs）of 7.3%and 6.4%,exhibiting excellent performance with minimal efficiency roll-off at high brightness levels.（2）Breaking from conventional molecular design strategies that typically employ spirocyclic units as peripheral components（such as side chains,end groups,or linkers）,our approach innovatively embeds rigid 9,9’-spirobifluorene（SF）units either fully or partially into boron/nitrogen multiple-resonance（B/N-MR）emissive cores.This led to the successful development of four isomeric MR-TADF materials（SF-BN1,SF-BN2,SF-BN3,SF-BN4）.These materials exhibited remarkably narrow full width at half maximum（FWHM）of 15-21nm in toluene solutions and achieved high PLQYs up to 90%in doped films.The OLED device based on SF-BN1 realized an EQE of 29.0%with CIE coordinates（0.13,0.08）fully compliant with the BT.2020 blue-light standard.Furthermore,the sky-blue OLED using SF-BN3 not only achieved an ultra-narrow FWHM of 18 nm and an EQE of 29.8%,but its hyperfluorescence（HF）device further boosted the efficiency to 35.5%.更多还原