A Simple Approach to Achieve Organic Radicals with Unusual Solid-State Emission and Extraordinary Stability

Herein, we report a simple approach to generate stableluminescent radicals in the presence of gentle UV irradiation. The newly generated radicalspecies are capable of emitting unusual red light with a maximum fluorescence quantumefficiency of 4.6% at ambient conditions in the solid state. Additionally, the luminescentradicals show extraordinary stability with more than one-year life-span at ambient conditions.X-ray diffraction study combined with photophysical and computational analyses reveal thatthe unique molecular symmetry breaking in the crystalline state lead to the unusual formationand stabilization of radical ion pairs via the photo-induced electron transfer (PET) process. Suchresults represent the first time to achieve stable emissive radicals in the solid state at ambientconditions via in-situ PET process.