Engineering the sign of circularly polarized emission in achiral polymer - chiral small molecule blends as a function of blend ratio
Engineering the sign of circularly polarized emission in achiral polymer - chiral small molecule blends as a function of blend ratio
复制标题
将非手性聚合物-手性小分子共混物中的圆偏振发射符号设计为共混比的函数
DOI：
10.1039/d1tc05403a
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发表时间：
2022
影响因子：
6.4
通讯作者：
Wan L
中科院分区：
文献类型：
--
作者：
Wan L
圆偏振有机发光二极管（CP-OLED），展示了国家的最先进的效率和强圆偏振（CP）电致发光已被证明是一个相当大的技术挑战。此外，多个因素-从膜厚度到器件结构-已被证明会影响所发射的CP光的符号，而与手性发射体的手性（绝对立体化学）无关。在这里，我们报告了使用聚（9，9-二辛基芴-alt-联噻吩）（F8 T2）和手性小分子添加剂（1-氮杂[6]螺烯，氮杂[6]H）的共混物的CP-OLED。我们展示了具有令人印象深刻的电致发光不对称性（gEL）> 0.3，电流效率为0.53 cd A−1，亮度为3023 cd m−2的CP-OLED。虽然在低氮杂[6]H负载下，F8 T2共混物与先前观察到的CP不对称反转作为膜厚度/激发模式的函数一致，但氮杂[6]H的较高负载（约40重量%）消除了这种依赖性，同时保留了优异的g因子。所公开的材料将允许手性聚合物材料的进一步机理研究，并为膜和装置中的手性光学优化提供新的机会。
Circularly polarized organic light-emitting diodes (CP-OLEDs) that demonstrate both state-of-the-art efficiency and strongly circularly polarized (CP) electroluminescence have proved a considerable technical challenge. Furthermore, multiple factors – from film thickness to device structure – have been shown to influence the sign of the emitted CP light, independent of the handedness (absolute stereochemistry) of the chiral emitter. Here we report CP-OLEDs using a blend of poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and a chiral small molecule additive (1-aza[6]helicene, aza[6]H). We demonstrate CP-OLEDs with an impressive electroluminescence dissymmetry (gEL) > 0.3 and a current efficiency of 0.53 cd A−1 and brightness of 3023 cd m−2. While at low aza[6]H loadings, F8T2 blends are consistent with previous observations of CP dissymetric inversion as a function of film thickness/excitation mode, a higher loading of aza[6]H (∼40 wt%) removes such dependencies while retaining excellent g-factors. The materials disclosed will allow for further mechanistic studies of chiral polymeric materials and provide new opportunities for chiroptical optimisation in films and devices.