Stable Open‐Shell Polymers via Precise Introduction of Oxygen Radicals with Quinoidal Resonance on Conjugated Donor‐Acceptor Backbones

ABSTRACT

The classic donor‐acceptor (D‐A) conjugated polymers are highly developed in organic electronics for their potential in organic light‐emitting diodes, organic field‐effect transistors, and organic photovoltaics. Since 2017, we reported aggregation‐induced radical (AIR) and ground‐state charge transfer (GSCT), which render these materials sensitive to oxygen doping and low stability in devices. In this work, we propose a strategy to design oxygen‐rich conjugated radical (ORCR) by intentionally incorporating oxygen‐centered radicals into the D‐A backbones. A series of D‐A polymers were synthesized via atom‐economical direct arylation polymerization, followed by quantitative post‐synthetic dealkylation to yield the corresponding oxygen‐radical polymers. The introduction of oxygen radicals showed highly lowered bandgap and highly quenched fluorescence, signaling an enhanced non‐radiative relaxation pathway. Electron paramagnetic resonance confirmed their high spin concentration with high air stability. Notably, BDTO ₂ ‐BBT exhibited an extraordinary photothermal conversion temperature of 170°C under 808 nm laser irradiation for 60 s, maintaining performance over multiple cycles. This study reported robust open‐shell ORCR materials but also provides a simple design paradigm for stable high‐spin organic radical semiconductors.