Electrochemically Assembled π–π Stacking Organic Radical‐Decatungstate With UV‐SWIR Solar Absorption for Efficiency Solar‐Thermal Conversion

Solar‐driven interfacial photothermal evaporation is a promising approach for desalination; however, its efficiency is often constrained by the narrow absorption range and relatively low photothermal conversion efficiency of existing photothermal materials. Here, we report a large‑anion‐stabilized radical π‐aggregate strategy to construct a stable organic radical‐decatungstate hybrid via mild and controllable electro‑oxidation. The resulting material exhibits full‑spectrum solar absorption with a high solar absorptivity of 95.85% and achieves a photothermal conversion efficiency of 98.24%. When fabricated into a 2D solar steam evaporator, it delivers a net evaporation rate of 1.40 kg·m −2 ·h −1 , approaching the theoretical limit. Further integration into a 3D solar steam evaporator enables long‑term and reliable seawater desalination without salt precipitation. Theoretical calculations reveal that the ultrabroad and intense absorption originates from organic radical π‑aggregates and inorganic polyanion‑synergized intermolecular and intramolecular transfer transitions. This work integrates electrochemical radical generation with the structural advantages of polyoxometalates (POMs) to create a low‐cost, stable, and full‑spectrum photothermal material, opening a new avenue toward efficient and sustainable solar‑driven desalination.