Open-shell radicals are usually thermodynamically and kinetically unstable due to their incompletely satisfied valency. However, the rapid development of radical chemistry in the past 100 years has demonstrated the possibility to prepare persistent and even stable radicals through rational design and appropriated chemical constructions. The existence of unpaired electrons of open-shell materials endows them with some unique physicochemical properties, which are difficult to be achieved in well-studied, closed-shell materials. This critical review summarizes some typical persistent and stable organic radicals, together with the presentations of their chemical synthesis and physicochemical properties. Furthermore, the up-to-date practical applications in magnetic, electronic, optoelectronic, and biologic fields based on functional organic radicals are presented. Finally, we carefully revise the critical limitations and challenges in radical chemistry and material functionalization, covering some core issues, including stability and commercialization perspectives, that need to be systematically considered in future.

开壳自由基由于不完全满足化合价而通常在热力学和动力学上不稳定。但是，在过去的100年中，自由基化学的快速发展证明了通过合理的设计和适当的化学结构制备持久甚至稳定的自由基的可能性。开壳材料的不成对电子的存在赋予它们某些独特的理化性质，而在经过深入研究的闭壳材料中很难实现。这篇重要的综述总结了一些典型的持久性和稳定性有机基团，并介绍了它们的化学合成和物理化学性质。此外，在磁性，电子，光电，介绍了基于功能有机自由基的生物领域。最后，我们仔细修改了自由基化学和材料功能化中的关键局限性和挑战，涵盖了一些核心问题，包括稳定性和商业化前景，这些都需要在以后系统地加以考虑。