New Molecular Design Concurrently Providing Superior Pure Blue, Thermally Activated Delayed Fluorescence and Optical Out-Coupling Efficiencies
New Molecular Design Concurrently Providing Superior Pure Blue, Thermally Activated Delayed Fluorescence and Optical Out-Coupling Efficiencies
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DOI：
10.1021/jacs.7b03848
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发表时间：
2017-08-16
影响因子：
15
通讯作者：
Cheng, C-H.
中科院分区：
文献类型：
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作者：
Rajamalli, P.;Senthilkumar, N.;Cheng, C-H.
同时提高热激活延迟荧光（TADF）发光体的外耦合效率、内量子效率和色纯度对于这些材料的实际应用是高度期望的。以二吡啶甲酮（DPyM）为新的受电子单元，二叔丁基咔唑（DTC）为给电子单元，设计并合成了两种异构体TADF发光体2DPyM-mDTC和3DPyM-pDTC。具有非常小的Δ E-ST的结构上接近平面的3DPyM-pDTC显示出比具有更柔性结构的2DPyM-mDTC更高的色纯度、水平比和量子产率。基于3DPyM-pDTC作为掺杂剂发射体的电致发光器件可以达到31.9%的极高的外量子效率，具有纯蓝色发射。这项工作还展示了一种方法来设计具有高水平分子取向的材料，以实现基于TADF发射器的高效纯蓝色器件。
Simultaneous enhancement of out-coupling efficiency, internal quantum efficiency, and color purity in thermally activated delayed fluorescence (TADF) emitters is highly desired for the practical application of these materials. We designed and synthesized two isomeric TADF emitters, 2DPyM-mDTC and 3DPyM-pDTC, based on di(pyridinyl)methanone (DPyM) cores as the new electron-accepting units and di(tert-butyl)carbazole (DTC) as the electron-donating units. 3DPyM-pDTC, which is structurally nearly planar with a very small Delta E-ST, shows higher color purity, horizontal ratio, and quantum yield than 2DPyM-mDTC, which has a more flexible structure. An electroluminescence device based on 3DPyM-pDTC as the dopant emitter can reach an extremely high external quantum efficiency of 31.9% with a pure blue emission. This work also demonstrates a way to design materials with a high portion of horizontal molecular orientation to realize a highly efficient pure-blue device based on TADF emitters.