Controlled Harnessing of Azobenzene Photoswitches in Neat States through Modulated Self-Assembled Mesogenic Nanostructures

This study introduces visible-light responsive self-assembled liquid crystals (LC) by the innovative integration of a tetra-ortho-substituted azobenzene dopant into imidazolium-based ionic liquid crystalline (ILC) host matrix. Comprehensive analyses using differential scanning calorimetry, polarized optical microscopy, and wide-angle X-ray scattering confirm the formation of various stable mesophases based on the amount of dopant. By synergistically combining the photoresponsiveness of azobenzene with the LC order of the ILC host, materials capable of efficient photothermal energy conversion in solid-states are engineered. This strategic fusion of components is designed to create a dynamic system with rapid photoswitching capabilities and substantial energy storage density. By meticulously modulating the concentration of azobenzene within the ILC matrix, materials with remarkable half-lives and charging capacity of up to 78% in thin films are engineered. The heat release dynamics, observed for films charged under green LED, revealed a significant energy storage and release, with a temperature increase of up to 6.3 °C. This work lays the foundation for a new generation of solar thermal fuels (STFs), where energy capture and release can be precisely controlled by doping the molecular photoswitch into the host LC matrices.