The development of blue electroluminescent (EL) materials remains a significant challenge in organic light-emitting diode (OLED) technology. In this study, a novel design strategy is proposed for blue hot exciton (HE) materials, which involves utilizing a “cross” shaped molecular structure characterized by substantial steric hindrance and a highly twisted conformation. The unique cross-shaped molecular architecture with distinct “arms” enables flexible control over the excited state properties of the molecule, thereby facilitating precise modulation of high-lying triplet and low-lying singlet excited state energy levels. Furthermore, the 3D spatial configuration of the molecule effectively reduces close molecular packing, thereby minimizing the risk of material concentration quenching. The proof-of-concept HE emitters CN-PI and TP-PI exhibit non-π-π stacking configurations in single crystals, achieving high photoluminescence quantum yield (PLQY) values up to 51.3% and 46.5% in non-doped thin films, respectively, along with rapid radiation decay rates and reasonable distribution of T_m (m ≤ 5) and S₁ states. Non-doped OLEDs incorporating these emitters demonstrate exceptional external quantum efficiencies (EQE), reaching 7.3% and 6.4%, respectively, while exhibiting minimal efficiency roll-off at high luminance. This research introduces a promising approach for developing high-performance blue HE emitters.

中文翻译：

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基于“十字”形热激子发射器的高效蓝色有机发光器件


蓝色电致发光 （EL） 材料的发展仍然是有机发光二极管 （OLED） 技术面临的重大挑战。在这项研究中，提出了一种新的蓝热激子 （HE） 材料设计策略，该策略涉及利用具有大量空间位阻和高度扭曲构象的“交叉”形分子结构。独特的十字形分子结构具有不同的“臂”，可以灵活控制分子的激发态特性，从而促进高位三重态和低位单重态激发态能级的精确调制。此外，分子的 3D 空间配置有效地减少了紧密的分子堆积，从而最大限度地降低了材料浓度淬灭的风险。概念验证 HE 发射器 CN-PI 和 TP-PI 在单晶中表现出非π π堆叠配置，在非掺杂薄膜中分别实现了高达 51.3% 和 46.5% 的高光致发光量子产率 （PLQY） 值，以及快速的辐射衰减速率和 T_m （m ≤ 5） 和 S₁ 态的合理分布。包含这些发射器的非掺杂 OLED 表现出卓越的外部量子效率 （EQE），分别达到 7.3% 和 6.4%，同时在高亮度下表现出最小的效率滚降。本研究介绍了一种开发高性能蓝色 HE 发射器的有前途的方法。