Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education & School of Chemistry and Material Science, Heilongjiang University, 74 Xuefu Road, Harbin, 150080, P. R. China.
Adv Mater. 2018 Dec;30(50):e1804228. doi: 10.1002/adma.201804228. Epub 2018 Oct 10.
Efficient blue emitters are indispensable for organic light-emitting diodes (OLEDs) with respect to display and lighting applications. Because of their high-energy excited states, both radiation enhancement and non-radiation suppression should be simultaneously optimized to realize 100% exciton utilization. Here, it is shown that the excited-state characteristics of blue thermally activated delayed fluorescence emitters can be precisely controlled by a secondary acceptor having moderate electronic effects on increasing the singlet charge-transfer component and preserving the triplet locally excited-state component. In addition of planar configuration between the donor and the primary acceptor, the radiative transition improvement and non-radiative transition suppression can be simultaneously achieved for "full-exciton radiation". A molecule using diphenylphosphine oxide as the secondary acceptor exhibits ≈100% photoluminescence quantum yield on the basis of its tenfold increased singlet radiative rate constant, fivefold decreased singlet and triplet non-radiative rate constants, and ≈100% reverse intersystem crossing efficiency, which further endows ≈100% exciton utilization efficiency to its sky-blue OLEDs.
高效的蓝色荧光体对于用于显示和照明应用的有机发光二极管（OLED）来说是不可或缺的。由于其高能激发态，应同时优化辐射增强和非辐射抑制，以实现 100%的激子利用。本文表明，通过具有适度电子效应的次级受体，可以精确控制蓝色热激活延迟荧光荧光体的激发态特性，从而增加单重态电荷转移分量并保留三重态局域激发态分量。除了供体和主要受体之间的平面构型之外，还可以同时实现“全激子辐射”的辐射跃迁改善和非辐射跃迁抑制。基于其单重态辐射速率常数增加了十倍、单重态和三重态非辐射速率常数降低了五倍以及反向系间窜越效率约为 100%，使用二苯基氧化膦作为次级受体的分子表现出约 100%的光致发光量子产率，这进一步赋予其天蓝色 OLED 约 100%的激子利用效率。
