Single molecule coupling of light and thermal for programmable energy storage

Efficiently integrating solar and ambient thermal energy within a single molecular system remains a significant challenge. Here we systematically construct a family of azobenzene-based molecules in which photoisomerizable cores are covalently coupled with thermally active alkyl and alkenyl segments. Unlike previous studies focusing on isolated examples, our approach establishes a homologous molecular series that enables direct correlation between structural parameters and dual-mode energy storage behavior. Upon ultraviolet irradiation, the trans -cis isomerization induces lattice disorder and photo‐liquefaction, allowing simultaneous capture of photon energy and latent heat. The reverse process triggered by light or heat releases both chemical and phase-change enthalpies in a single synergistic step. The system exhibits a gravimetric energy density exceeding 300 J g −1 , demonstrating a competitive performance among reported materials. Combined density functional theory and calorimetric analyses quantitatively link the isomerization energetics with crystal packing variations, establishing a predictive relationship between molecular design and thermophysical performance. This systematic strategy provides a data-driven framework for designing programmable photothermal materials and paves the way for high-throughput molecular energy computation.