Dual‐Quinoid Backbone Synergistic with Side‐Chain Engineering Enables Ultrahigh‐Temperature Conjugated Polymers for Bridging Solar‐ and Laser‐Driven Photothermal Applications

Abstract 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‐2C 8 exhibiting greater rotational freedom and weaker interchain interactions. Under 808 nm laser irradiation (1.2 W cm ‒2 ), PAQM‐TbT‐2C 8 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‐2C 8 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.