Radical-based light-emitting diodes are an innovative type of organic light-emitting diodes (OLEDs), which adopt luminescent radicals as emitters, aiming at improving the external quantum efficiency (EQE) of OLEDs. Research on luminescent radicals and the corresponding devices is a multidisciplinary field involving organic chemistry, solid-state physics, photochemistry, electronics, and others. The relevant theories have been established step-by-step in recent years. Considering the rapid development tendency, it is time to systematically summarize and discuss the doublet emission mechanism in devices, as well as the design principles of stable luminescent radicals. It is also of great importance to point out future developments in this area. In this minireview, the relevant advancements on radical-based OLEDs and stable radicals, especially those possessing luminescent properties, are summarized, respectively. Besides, the doublet emission mechanism is elaborated systematically. Some novel findings on stable luminescent radicals are also introduced. Finally, future developments and challenges in this field are presented.

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具有双重态发射的稳定的发光基团和基于基团的LED

基于自由基的发光二极管是一种创新类型的有机发光二极管（OLED），该有机发光二极管采用发光自由基作为发射器，旨在提高OLED的外部量子效率（EQE）。发光自由基及其相应器件的研究是一个涉及有机化学，固态物理学，光化学，电子学等领域的多学科领域。近年来，相关理论已逐步建立。考虑到快速发展的趋势，是时候系统地总结和讨论器件中的双峰发射机理，以及稳定的发光基团的设计原理了。指出这一领域的未来发展也非常重要。在本迷你评论中，有关基于自由基的OLED和稳定自由基的相关进展，特别是分别总结了具有发光特性的那些。此外，系统地阐述了双重发射机理。还介绍了有关稳定发光自由基的一些新发现。最后，介绍了该领域的未来发展和挑战。