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-stannylated 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.