Dual-Quinoid Backbone Synergistic with Side-Chain Engineering Enables Ultrahigh-Temperature Conjugated Polymers for...

Organic photothermal materials often perform efficiently under either solar or laser irradiation, yet achieving dual high performance within one system remains a formidable challenge due to stringent molecular design requirements. Here, we present a dual-quinoid backbone strategy-incorporating quinoidal and proquinoidal units-synergistically combined with side-chain engineering in conjugated polymers. Two dual-quinoid polymers with linear or bulky alkyl side chains are synthesized and benchmarked against the mono-quinoid analogue PAQM-3T. Incorporation of proquinoidal unit enhances quinoidal resonance, diradical character, and reorganization energy, yielding broadened near-infrared absorption with a laser-resonant peak near 808 nm, suppressed radiative loss, and superior photothermal conversion. Side-chain engineering further regulates backbone planarity and intramolecular rotation, with the bulky-chain derivative PAQM-TbT-2C₈ exhibiting greater rotational freedom and weaker interchain interactions. Under 808 nm laser irradiation (1.2 W cm^‒2), PAQM-TbT-2C₈ achieves an ultrahigh temperature of 356.0 °C, one of the highest values reported among all photothermal material classes, and maintains excellent photostability. Beyond laser-driven high-temperature applications, PAQM-TbT-2C₈ enables solar-driven water evaporation rate of 2.78 kg m^‒2 h^‒1 under 1 sun, setting a new record for Janus interfacial evaporators employing pure organic photothermal absorbers. This synergistic molecular design enables multifunctional organic photothermal materials bridging solar energy harvesting with laser-driven thermal applications.