Thermally Activated Delayed Fluorescent Dendrimers that Underpin High‐Efficiency Host‐Free Solution‐Processed Organic Light‐Emitting Diodes
Thermally Activated Delayed Fluorescent Dendrimers that Underpin High‐Efficiency Host‐Free Solution‐Processed Organic Light‐Emitting Diodes
复制标题
DOI：
10.1002/adma.202110344
复制
发表时间：
2022-04
影响因子：
29.4
通讯作者：
Dianming Sun;Eimantas Duda;Xiaochun Fan;Rishabh Saxena;M. Zhang;S. Bagnich;Xiaohong Zhang;A. Köhler;E. Zysman‐Colman
中科院分区：
文献类型：
--
作者：
Dianming Sun;Eimantas Duda;Xiaochun Fan;Rishabh Saxena;M. Zhang;S. Bagnich;Xiaohong Zhang;A. Köhler;E. Zysman‐Colman
高性能溶液处理有机发光二极管（OLED）的开发仍然是一个挑战。一个有效的解决方案，在这项工作中强调，是使用高效的热激活延迟荧光（TADF）树枝状聚合物作为发射体。在这里，三个三嗪基树枝状聚合物，tBuCz 2 pTRZ，tBuCz 2 mTRZ，和tBuCz 2 m2 pTRZ的设计，合成，密度泛函理论（DFT）建模，和电子物理学的报告，解决了矛盾的要求，同时实现一个小的ΔEST和一个大的振荡器强度通过将Meta和帕拉连接的供体树枝状分子的中心三嗪受体。含有无主体发光层的溶液处理的OLED表现出28.7%的优异的最大外部量子效率（EQEmax）、98.8 cd A−1的电流效率和91.3 lm W−1的功率效率。该器件发射的电致发光最大值λEL为540 nm，国际照明委员会（CIE）色坐标为（0.37，0.57）。这代表了迄今为止报道的最有效的无基质溶液处理OLED。针对改善器件内的电荷平衡的进一步优化导致包含30重量% OXD-7的发射层，这导致具有28.4%的类似EQE max的OLED，但显示出显著改善的效率滚降，其中在500 cd m-2的亮度下EQE保持在22.7%的高水平。
The development of high‐performance solution‐processed organic light‐emitting diodes (OLEDs) remains a challenge. An effective solution, highlighted in this work, is to use highly efficient thermally activated delayed fluorescence (TADF) dendrimers as emitters. Here, the design, synthesis, density functional theory (DFT) modeling, and photophysics of three triazine‐based dendrimers, tBuCz2pTRZ, tBuCz2mTRZ, and tBuCz2m2pTRZ, is reported, which resolve the conflicting requirements of achieving simultaneously a small ΔEST and a large oscillator strength by incorporating both meta‐ and para‐connected donor dendrons about a central triazine acceptor. The solution‐processed OLED containing a host‐free emitting layer exhibits an excellent maximum external quantum efficiency (EQEmax) of 28.7%, a current efficiency of 98.8 cd A−1, and a power efficiency of 91.3 lm W−1. The device emits with an electroluminescence maximum, λEL, of 540 nm and Commission International de l'Éclairage (CIE) color coordinates of (0.37, 0.57). This represents the most efficient host‐free solution‐processed OLED reported to date. Further optimization directed at improving the charge balance within the device results in an emissive layer containing 30 wt% OXD‐7, which leads to an OLED with the similar EQEmax of 28.4% but showing a significantly improved efficiency rolloff where the EQE remains high at 22.7% at a luminance of 500 cd m−2.