Solar molecule locks sunlight in bonds, beats lithium-ion density

Chemists at UC Santa Barbara have developed a novel molecule based on a modified organic compound called pyrimidone that can capture sunlight and store it chemically for years, releasing the stored energy as heat powerful enough to boil water. This innovation belongs to the field of Molecular Solar Thermal energy storage (MOST), which differs from traditional solar panels by storing solar energy directly within molecular bonds rather than converting it to electricity. The molecule functions like a mechanical spring: it twists into a high-energy, strained configuration upon sunlight exposure and remains stable until triggered by heat or a catalyst to release the stored energy as heat. This process is reversible and recyclable, allowing repeated use without bulky batteries or complex infrastructure. Inspired by DNA components that undergo reversible changes under UV light, the researchers engineered a compact, lightweight molecule optimized for stability and energy storage. Computational modeling helped understand how the molecule maintains its high-energy state over time. The molecule achieves an energy density exceeding 1.6 megajoules per kilogram, roughly double that of typical