摘要
设计合成高效发光材料对于蓝光有机发光二极管(OLED)的进一步研究和应用至关重要.以扭曲七元环结构的9H-三苯并[b,d,f]氮杂䓬(TPA)为给体,设计合成了两种新型蓝光发光分子TRZCz-TPA和TRZ-TPA,并对它们的热稳定性、电化学性质、光物理性质和器件性能等进行了表征.光谱研究表明,TRZCz-TPA和TRZ-TPA均为蓝光发射,其甲苯溶液中的发射波长分别为455和440 nm.和TRZ-TPA分子不同的是,TRZCz-TPA的受体邻位引入3,6-二叔丁基咔唑(tBuCz),产生较大的空间位阻,使得二苯基三嗪(TRZ)受体构型扭曲,与苯环π-桥平面存在较大二面角,从而最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)分别转移到tBuCz给体和TRZ受体上,其发光性质由TPA给体到TRZ受体的沿键电荷转移特性(TBCT)转变为tBuCz给体到TRZ受体的空间电荷转移特性(TSCT),单三线态能隙(ΔEST)从0.53 eV显著降至0.04 eV,具有热活化延迟荧光(TADF)性质.此外,大位阻的tBuCz给体可以降低聚集态下的发光猝灭现象,因此,TRZCz-TPA掺杂薄膜的光致发光量子产率(PLQY)为42.0%,掺杂器件的最大外量子效率(EQEmax)为10.4%,而TRZ-TPA的PLQY和EQEmax仅为6.5%和3.7%.
The development of efficient blue light-emitting materials is a crucial yet challenging task in organic light-emitting diodes(OLED).Two novel blue light-emitting molecules,TRZCz-TPA and TRZ-TPA,have been designed and synthesized based on the heptagonal 9H-tripheno[b,d,f]nitrozoafluorene(TPA)donor.Their thermal stability,electrochemical properties,photophysical properties,and device performances were characterized.TRZCz-TPA and TRZ-TPA both exhibit blue emission in toluene solution with emission peaks at 455 and 440 nm,respectively.In contrast to TRZ-TPA,which exhibits through-bond charge transfer(TBCT)from the TPA donor to the diphenyltriazine(TRZ)acceptor,TRZCz-TPA,featuring two adjacent 3,6-di-tert-butylcarbazole(tBuCz)donors near the TRZ acceptor,demonstrates through-space charge transfer(TSCT)from the tBuCz donors to the TRZ acceptor.This leads to a remarkable reduction in the singlet-triplet energy gap(ΔEST)from 0.53 eV to 0.04 eV,thereby displaying thermally activated delayed fluorescence(TADF)properties.Additionally,tBuCz donor with large steric hindrance effectively suppresses aggregation-induced quenching in the aggregated state.Consequently,TRZCz-TPA achieves a photoluminescence quantum yield(PLQY)of 42.0%and a maximum external quantum efficiency(EQEmax)of 10.4%in OLED devices,significantly outperforming TRZ-TPA(PLQY=6.5%,EQEmax=3.7%).
作者
李治
李祯龙
刘俊杰
憨卫国
游劲松
宾正杨
Zhi Li;Zhenlong Li;Junjie Liu;Weiguo Han;Jingsong You;Zhengyang Bin(College of Chemistry,Sichuan University,Chengdu 610065)
出处
《有机化学》
SCIE
CAS
CSCD
北大核心
2024年第6期2006-2013,共8页
Chinese Journal of Organic Chemistry
基金
国家自然科学基金(No.22275127)资助项目
关键词
有机发光二极管
热活化延迟荧光
沿键电荷转移
空间电荷转移
七元环三芳胺给体
organic light-emitting diodes
thermally activated delayed fluorescence
through-bond charge transfer
through-space charge transfer
heptagonal triarylamine donor
