Stable Organic Radicals Participation in Charge Transfer: A New Strategy toward Molecular Functional Materials

Charge-transfer (CT) engineering with inter-/intramolecular CT interactions by simple compositions has emerged as a universal and efficient way to construct organic functional materials. Stable organic radicals with unique physicochemical properties that cannot be realized in closed-shell molecules, have been widely demonstrated to be ideal building blocks to construct versatile organic CT materials. This concept article provides a brief overview of the advances in the design, structure and property of stable organic radicals-based CT molecular functional materials, and the strategy for the generation of these materials is also highlighted. First, radicals are introduced as open-shell donors or acceptors, with a focus on their importance and uniqueness in improving electrical, magnetic and optical properties of CT functional materials. Additionally, CT interactions in stable radical dimers and trimers are further discussed systematically. Finally, the challenges are summarized and perspectives for future development of stable organic radicals-based CT functional materials are provided.