Molecular solar thermal energy storage in Dewar Pyrimidone beyond 1.6 MJ/kg

Storing sunlight in a compact and rechargeable form remains a central
challenge for solar energy utilization. Molecular solar thermal (MOST)
energy storage systems, which harness photon energy and release it as heat
on demand, provide a direct approach, but have long failed to meet
practical benchmarks. Inspired by the architecture of DNA, we report a
pyrimidone-based MOST system that stores energy in the strained Dewar
photoisomer upon excitation at 300 nm. Designed with sustainability in
mind, the system operates solvent-free and remains compatible with aqueous
environments while overcoming one of the field’s greatest hurdles: the
controlled extraction and transfer of stored heat. When catalyzed by acid,
the Dewar isomer releases enough heat to boil water (~0.5 mL). These
advances help point the way toward decentralized solar heat storage and
off-grid energy solutions.