Molecular regulation of nano-structured solid-state AZO-SWCNTs assembly film for the high-energy and short-term solar thermal storage

Abstract A closed-cycle system by storing and releasing solar energy without additional interchange of material is crucial for future high global energy demands. Here, we presented a solid-state molecular solar thermal fuels (STFs) composed of single-walled carbon nanotubes and azobenzene with push-pull electron structure (AZO-SWCNTs) employing the direct Friedel-crafts acylation reaction. This kind of STFs reveals the highest gravimetric energy density of 80.7 Wh kg −1 and power density of 292 W kg −1 in AZO-CNTs STFs system with extended half-lifetime and excellent photochemical cycling stability. Moreover, the high performance and closed cycle of storage and heat release of the solid-state STFs assembly film were also investigated. The STFs shows relatively a high energy storage efficiency (12.4%) and a solar energy storage efficiency (0.25%) with a maximum temperature difference of 10 °C. This kind of solid-state STFs film exhibits a great potency in high-energy and short-term solar energy thermal storage.