D_(1)-A-D_(2)型高效红光热激活延迟荧光有机发光二极管

High-Efficiency Organic Light-Emitting Diodes With D_(1)-A-D_(2) Type Red Thermally Activated Delayed Fluorescence

采用吩噁嗪(PXZ)片段作为具有分子刚性的强电子供体(D_(1))、三苯胺(TPA)片段作为具有大空间位阻的强电子供体(D_(2))、杂环芳烃构成的二苯并吩嗪(dibenzo[a,c]phenazine,BP)片段作为具有较强刚性的电子受体(A),开发了一种具有供体-受体-供体(D_(1)-A-D_(2))型结构的新型高效红光热激活延迟荧光(TADF)材料(2T-BP-2P)。通过紫外-可见分光(UV-Vis)光谱、光致发光(PL)光谱、热重分析(TGA)和差示扫描量热(DSC)等对2T-BP-2P的光物理、电化学和热学性能进行了表征。结果表明,基于2T-BP-2P的器件实现了614.5 nm的红光发射,其外部量子效率(EQE)高达12.2%,国际照明委员会(CIE)坐标为(0.59,0.40)。

At present,the development of novel high performance red thermally activated delayed fluorescence(TADF)materials still faces great challenges.In this work,the phenoxazin(PXZ)fragment was used as the strong electron donor with molecular rigidity(D_(1)),the triphenylamine(TPA)fragment was used as the strong electron donor with large steric hindrance(D_(2)),and the dibenzo[a,c]phenazine(BP)fragment composed of heterocyclic aromatic hydrocarbon was used as the strong electron acceptor(A).With the three fragments,a new high efficiency red TADF emitter with donor-receptor-donor(D1-AD2)structure,4,4'-(3,6-di(10H-phenoxazin-10-yl)dibenzo[a,c]phenazine-11,12-diyl)bis(N,N-diphenylaniline)(2T-BP-2P),was designed.The photophysical,electrochemical and thermal properties of 2T-BP-2P were characterized by ultraviolet-visible(UV-Vis)absorption,photoluminescence(PL),thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC),respectively.At the same time,2T-BP-2P was characterized and confirmed by nuclear magnetic resonance(NMR)and mass spectrometry(MS)technology.Results showed that 2T-BP-2P had a high photoluminescence quantum yield(ΦPL)of 78.5%in the 15%mass fraction doped films with 4,4′-bis(N-carbazolyl)-1,1′-biphenyl(CBP)as a host material.The device based on 2T-BP-2P achieved red emission at 614.5 nm,maximum external quantum efficiency(EQEmax)of 12.2%,and the Commission International de l'Eclairage(CIE)coordinate of(0.59,0.40).What’s more,the lowest turn-on voltage (Von) was 2.9 eV, and the highest power efficiency (PE) and current efficiency (CE) of the device were 17.37 lm/W and 17.70 cd/A, respectively. The superior performance of this device is at the leading level among the known red-doped TADF-organic light-emitting diodes (OLEDs). A new strategy for the future development of high-performance red-emitting OLEDs is provided.