Controllable heat release of phase-change azobenzenes by optimizing molecular structures for low-temperature energy utilization

Phase-change azobenzene derivatives can store and release heat upon isomerization. The amount rate of output are affected by the crystallization isomerization, which in turn governed molecular structure interactions. Thus, optimizing is a promising method to control at different temperatures. Herein, we prepared three asymmetric alkoxy-substituted molecules (s-Azo) with similar weights but substituents investigate trade-off between Temperature-dependent crystallizability photo-induced iso-merization kinetics all s-Azo were studied. Results indicate that n-alkoxy substitution endows high enthalpy (ΔHCE) due strong van der Waals forces, steric hindrance lowers degree Short branched alkyl reduces intermolecular interactions favors leads an increase isomerization (ΔHIE) decreases ΔHCE. n-alkoxy-substituted exhibits photoinduced high-energy up 343.3 J g−1 power density 413 W kg−1 wide temperature range from −60.49 34.76°C. synchronous distributed energy utilization annular device achieves rise 6.3°C low environment (−5°C). demonstrate phase-change be designed developed for ideal energy-storage systems structures