Preparation of Photoresponsive Film via Electrodeposition Approach for Ready‐to‐Use Solar Thermal Fuel Device

Abstract Azobenzene and its derivatives are proposed as promising solar thermal fuel (STF) candidates due to the unique photoinduced trans – cis isomerization. However, the routinely processed azobenzene/inorganic–nonmetal nanocomposite‐based STF usually encounters the problems of close‐packed structure and the poor penetration of UV light, which need a solvent pretreatment charging process before STF application. Electrochemical deposition (ED) is widely used in the preparation of photoelectric functional devices because of its unique polymerization and deposition process. Here, an azobenzene‐based cross‐linking film is successfully prepared from a new functionalized azobenzene derivative, BCz‐BO‐Azo, by ED approach to develop a ready‐to‐use STF film without any pretreatments. The energy density of BCz‐BO‐Azo is 101 J g −1 , and the energy storage half‐life of BCz‐BO‐Azo ED film is extended by 750% compared with that of pristine BCz‐BO‐Azo solid. The charged BCz‐BO‐Azo ED film also can release thermal energy to heat up itself quickly under a certain external stimulus. Due to the fast charging process, long energy storage half‐life, and quick stimulated release of the BCz‐BO‐Azo ED film, this kind of ready‐to‐use STF has distinct superiority in daily use, such as self‐defrosting glasses, building wall insulation, and solar energy transport.