Stable Diradical‐Derived Conjugated Radical Polymers

Conjugated radical polymers (RPs) with polyradical structures in an π‐conjugated polymeric backbone have the potential to serve as both model molecules for spin‐correlated condensed matters and as materials for optoelectronics and spin‐based quantum applications. However, preparing RPs of this type with high stability and spin‐delocalized nature presents a significant challenge. We report herein two ambient‐stable conjugated RPs (RPH and RPC), synthetically obtained by an unprecedented straightforward copolymerization of two brominated diradical monomers (diradical characters up to 0.88) with bis‐stannalyted DPP units. Compared to diradical monomers with a singlet open‐shell ground state, the diradical‐derived RPs gave rise to favorable spin‐delocalization of conjugated polyradicals over macromolecular chain with ground states of S = 1/2, accompanied by featured electronic properties including intense near‐infrared absorptions beyond 1000 nm, multi‐stage amphoteric redox characteristics, and intriguing π‐paramagnetism in solution and solid states. Impressively, thin‐film state RPH exhibited superior ambipolar carrier‐transporting properties with well‐balanced hole/electron mobility of up to 0.41/0.38 cm2 V−1 s−1 as well as attractive room‐temperature quantum coherence times (T1 = 1.88 μs, T2 = 218 ns), reflecting practical significance for quantum information manipulations. This study introduces a facile approach for constructing stable conjugated RPs, along with their integrated electronic and spin properties.