Record‐High Solar‐to‐Vapor Generation Efficiency via Synergistic Optimization of Absorption and Nonradiative Decay in Quinoid–Donor–Acceptor Polymers for Solar–Thermal Applications

ABSTRACT Organic photothermal materials based on conjugated structures hold great potential for solar harvesting but are often constrained by narrow absorption and limited solar–thermal conversion efficiency. A general molecular design strategy that can simultaneously broaden absorption and enhance nonradiative decay remains elusive. Here, we pioneer a quinoid–donor–acceptor (Q–D–A) architecture specifically tailored for photothermal applications. Incorporating quinoidal unit into a D–A polymer backbone yields the novel polymer PAQM‐TBz, which exhibits a reinforced backbone planarity, intensified π–π interactions, and enhanced diradical character compared with its D–A analogue, P2T‐TBz. These synergistic features enable broadband absorption (400–1500 nm) and rapid nonradiative relaxation, yielding an outstanding photothermal conversion efficiency of 80.6% under 808 nm laser irradiation—nearly twice that of P2T‐TBz. Under 1.0 kW m ‒2 simulated sunlight, PAQM‐TBz achieves a record‐high solar‐to‐vapor efficiency of 97.3% with an evaporation rate of 1.41 kg m ‒2 h ‒1 . It also generates a peak thermoelectric voltage of 126.1 mV, and in integrated water–electricity cogeneration, attains an evaporation rate of 1.28 kg m ‒2 h ‒1 and a voltage 95.8 mV, ranking among the highest for organic materials. This work establishes the Q–D–A strategy as a transformative platform for advanced solar–thermal energy conversion and multifunctional solar‐harvesting applications.