Low voltage piezo-electrophoretic films and displays including low profile piezo-electrophoretic films. Piezo-electrophoretic displays having a layer of electrophoretic material, a first conductive layer, and a piezoelectric material positioned between the layer of electrophoretic material and the first conductive layer, where the piezoelectric material overlaps with a portion of the layer of electrophoretic material, and a portion of the first conductive layer overlaps with the rest of the electrophoretic material. Such films and displays exhibit a high contrast ratio and are useful as security markers, authentication films, or sensors. The films and displays are generally flexible. Some are less than 100 μm in thickness. Some are less than 50 μm in thickness. Piezo-electrophoretic films and displays formed according to the technology described herein do not require an external power source to change optical state.