Visualization of azobenzene mesogens trans-cis isomerization through structural color of photonic crystal

Azobenzene, a representative photoresponsive liquid crystal, has extensive applications in fields such as bionic robotics, actuators, artificial muscles, motors, and various functional devices. Photoisomerization ( trans-cis isomerization) is the most important mechanism for its photoresponse. Currently, the isomerization of azobenzene mesogens can be measured through UV–vis absorption spectra, NMR techniques or transient grating methods. Visualization of the trans-cis isomerization of azobenzene mesogens still remains a challenge. In this study, a linear relationship is observed between the absorption intensity of azobenzene mesogens and the stopband shift of azobenzene inverse opals (AZOIOs) films during the isomerization process. This phenomenon can be used to determine the isomerization degree of azobenzene mesogens through the switching of the stopband of the AZOIOs film, enabling the visualization of the azobenzene mesogens’s configuration transition. The results of this study are highly significant for the design and fabrication of novel azobenzene devices.