Stable Radicals in Dihydrophenazine Derivatives‐Doped Epoxy Resin for High Photothermal Conversion

Abstract Organic radicals exhibit great potential in photothermal applications, however, their innate high reactivity with oxygen renders the preparation of stable organic radicals highly challenging. In this work, a series of co‐doped radical polymers ares prepared by doping dihydrophenazine derivatives (DPPs) into the epoxy resin matrix. DPPs can form radical species through the electron transfer process, which are further stabilized by the complex 3D network structure of epoxy resin. Experimental results show that the photothermal conversion efficiency is as high as 79.9%, and the temperature can quickly rise to ≈130 °C within 60 s. Due to the excellent visible light transmittance and mechanical properties of co‐doped systems, this study further demonstrates their practical applications in energy‐saving solar windows and thermoelectric power generation.