Chemical design for high performance blue organic light-emitting diodes

自人工照明技术出现以来，缺乏高性能的蓝色发光二极管（LED）一直是科学界的瓶颈。然而，2014年诺贝尔物理学奖授予了赤崎、天野和中村，以表彰他们对开发期待已久的基于氮化镓（GaN）的高效蓝色LED的贡献。然而，尽管无机半导体技术在电子工业中取得了许多成功，但这些设备可能成本高昂且难以制造。相反，塑料电子领域利用有机半导体材料，这些材料更具成本效益，可在低温下从溶液中加工，并且通过改变其独特的分子结构有效地无限调谐。尽管红色和绿色有机发光二极管（OLED）的开发相对容易，但蓝色有机发光二极管仍然存在寿命短和缺乏色彩纯度的问题，这最终阻碍了新设备架构的商业化和与替代技术的竞争力。自2015年以来，一种被称为多共振热激活延迟荧光（MR-TADF）发射器的新型分子材料引起了人们的极大兴趣，因为它们可以负担得起具有高效率和颜色纯度的深蓝设备。然而，它们目前也受到寿命短的限制。在此，我们建议通过结合分子包封合成策略和光谱学研究来更深入地了解MR-TADFs降解背后的光物理学。希望对光物理学的更深入的了解将使我们更好地合理设计性能更高的新材料，并减少在该领域看到的“试错”方法的使用。

The lack of a high performance blue Light Emitting Diode (LED) has been a bottleneck in the scientific community since the advent of artificial lighting technologies. However, in 2014 the Nobel Prize in Physics was awarded to Akasaki, Amano, and Nakamura for their contribution to the development of the long-awaited highly efficient blue LED based on Gallium Nitride (GaN). However, despite the many successes of inorganic semiconductor technology in the electronics industry, these devices can be costly and difficult to fabricate. Instead, the field of plastic electronics utilises organic semiconductor materials which are more cost-effective, processable from solutions at low temperatures, and effectively infinitely tuneable through the alteration of their unique molecular structures. Despite the relative ease in the development of the red and green Organic LED (OLED), the blue OLED still suffers from short lifetimes and a lack of colour purity, which ultimately hinders the commercialisation of novel device architectures and competitiveness with alternative technologies. Since 2015, a new class of molecular materials known as Multi-Resonant Thermally Activated Delayed Fluorescence (MR-TADF) emitters have been of significant interest because they can afford deep-blue devices with high efficiencies and colour purity. However, they are also currently limited by their short lifetimes. Herein, we propose to provide greater insight into the photophysics underlying the degradation of MR-TADFs through combining a molecular encapsulation synthetic strategy and optical spectroscopy studies. It is hoped that a greater understanding of the photophysics will better place us to rationally design higher performing novel materials and reduce the use of 'trial-and-error' approaches seen within the field.