Abstract
Recently discovered designs of solid-state molecular solar thermal energy storage systems are illustrated, including alkenes, imines, and anthracenes that undergo reversible [2+2] and [4+4] photocycloadditions for photon energy storage and release. The energy storage densities of various molecular designs, from 6 kJ/mol to 146 kJ/mol (or up to 318 J/g), are compared and summarized, along with the effective strategies for engineering their crystal packing structures that facilitate the solid-state reactions. Many promising molecular scaffolds introduced here highlight the potential for achieving successful solid-state solar energy storage, guiding further discovery and development of new molecular systems for applications in solid-state solar thermal batteries.