Aromaticity‐Engineered Open‐Shell Radical Anions for Air‐Stable Doublet Emission in N ‐Annulated Perylene Diimide

ABSTRACT We report the doublet emissive open‐shell radical anions, where the N ‐annulated perylene diimide (PDIN–H) is functionalized with aromatic rings. This resulting [ PDI – MeR ] ^•− (R = BZ, benzene; NP, naphthalene; PY, pyrene) shows a high quantum yield, a long lifetime, and a high stability in air, as the ring size increases. The key to these properties is the combination of PDIN's aromaticity with predominant through‐space charge‐transfer (TSCT). This finding provides fundamental insights into unique open‐shell electronic structures and tunable optical functions, thereby paving the way for the development of novel doublet emitters and electroactive materials.