Significant efforts have been devoted to the development of novel efficient blue-emitting molecules for organic light-emitting diode (OLED) applications. Blue organic emitters exhibiting thermally activated delayed fluorescence (TADF) have the potential to achieve ∼100% internal electroluminescence quantum efficiency in OLEDs. In this paper, we report a promising molecular design strategy for obtaining appropriate high singlet and triplet excited energies, short exciton lifetimes, and high quantum efficiencies in blue TADF emitters. We introduce isobenzofuranone and chromone containing a cyclic ketone or lactone moiety as effective acceptor building units to construct donor–acceptor TADF emitters. Owing to their small singlet–triplet energy splitting, properly contracted π-conjugation, and weakened intramolecular charge-transfer character, these new emitters display strong blue TADF emissions with high photoluminescence quantum yields (53–92%) and notably short TADF emission lifetimes (2.8–4.3 μs) in thin films. Blue TADF-OLEDs utilizing these emitters exhibit external electroluminescence quantum efficiencies of up to 16.2% and extremely low efficiency roll-off even at practical high luminance. The current findings open new avenues for designing practically usable high-performance blue TADF emitters with simple molecular structures.

中文翻译：

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有机发光二极管中低效率滚降的异苯并呋喃酮和色酮基蓝色延迟荧光发射体

已经致力于开发用于有机发光二极管（OLED）应用的新型有效的蓝色发光分子。表现出热激活延迟荧光（TADF）的蓝色有机发射器有可能在OLED中实现约100％的内部电致发光量子效率。在本文中，我们报告了一种有前途的分子设计策略，可用于在蓝色TADF发射器中获得适当的高单重态和三重态激发能，短的激子寿命和高量子效率。我们引入含有环酮或内酯部分的异苯并呋喃酮和色酮作为有效的受体构建单元，以构建供体-受体TADF发射体。由于它们的单重态-三重态能量分裂小，π结合适当收缩，并且削弱了分子内电荷转移特性，这些新的发射器显示出高强度的蓝色TADF发射，具有高的光致发光量子产率（53–92％），并且在薄膜中的TADF发射寿命很短（2.8–4.3μs）。利用这些发射器的蓝色TADF-OLED，即使在实际的高亮度下，仍具有高达16.2％的外部电致发光量子效率和极低的滚降率。目前的发现为设计具有简单分子结构的实用的高性能蓝色TADF发射器开辟了新途径。