A Stable and Polar Triplet‐Ground‐State Conjugated Polymer With High Intrinsic Electrical Conductivity

ABSTRACT

Developing molecular materials with high intrinsic n ‐type electrical conductivity ( σ ) independent of extrinsic doping remains a formidable challenge in organic electronics. Herein, we report a novel acceptor–acceptor type open‐shell conjugated polymer (OSCP), PBBT‐gDPP, featuring a proquinoidal benzobis(1,2,5‐thiadiazole) (BBT)‐based backbone and polar oligo(ethylene glycol) side chains. In‐depth spectroscopic, electrochemical, and magnetic characterizations uncover that this acceptor–acceptor architecture, benefiting from its planar backbone and multiple proquinoidal units, yields an ultra‐narrow bandgap ( E _g < 0.6 eV), an open‐shell triplet ground state ( S = 1), and significant diradicaloid character. These features, complemented by polar side chains that modulate the local dielectric environment to assist in polaron transport, result in a high intrinsic σ of 9.21 S cm ⁻¹ with substantial ambient stability and a power factor of 6.49 µW m ⁻¹ K ⁻² when PBBT‐gDPP is applied as an n ‐type single‐component organic thermoelectric material. The conductivity surpasses those of previously reported undoped conjugated materials. Notably, the near‐amorphous morphology, characterized by a high paracrystalline disorder parameter of ∼23%, imparts exceptional mechanical robustness, retaining 80% of its initial σ s after 3000 bending cycles. This work underscores the significant potential of polar high‐spin OSCPs for next‐generation, dopant‐free, and flexible organic electronics.