Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

Azobenzene-based solar thermal fuels have undergone significant advancements over the past four decades, emerging as a promising technology for light-to-thermal energy conversion. While these materials exhibit considerable development potential, critical challenges remain that hinder their practical implementation. In this perspective, we systematically analyze four representative azobenzene-based solar thermal fuel systems including nanocarbon-hybrid, conjugated polymer, linear polymer, and small-molecule derivative formulations to trace their developmental trajectories and identify key limitations. Through this comparative analysis, we aim to clarify the current state of azobenzene-based solar thermal fuels, while mapping strategic pathways for future technological advancements in this rapidly evolving research field.