Compatibilization of a photochromic dibenzothienylperfluorocyclopentene dopant (Figure) and a ferroelectric SmC* liquid-crystal host is achieved if both host and dopant are terminated with trisiloxane oligomers, which results in nanosegregation. Photocyclization of the photochromic dopant causes a large modulation of the electric polarization via a photomechanical effect.