Light-Driven Domain Switching on a Photochromic Ferroelectric

Photochromic materials that undergo reversible structural transformations have been extensively investigated on their transition mechanism and electric and optic properties. However, switching the ferroelectric domain of such typical photochromic molecules has rarely been discussed. Here, we report a photochromic ferroelectric, namely, (E)-2,4-di-tert-butyl-(((2-fluorophenyl)imino)methyl)phenol (tBu-2-FSA), crystallizing in the R3c space group at room temperature. tBu-2-FSA undergoes a structural transformation via reversible enol-keto isomerization when being subject to light irradiation of various wavelengths. The reversible switching of the polarization of tBu-2-FSA under an external electric field verifies its ferroelectricity. More importantly, the erase and write of the ferroelectric domain on the surface layers of the tBu-2-FSA thin film can be governed by non-destructive irradiation of various light wavelengths. Thus, tBu-2-FSA is a photoswitching ferroelectric that does not rely on thermal dynamic phase transition, which is unrealizable by traditional ceramic ferroelectrics. This work will pave a way for the future of light-controlled smart materials and biomechanical materials science.