Electrically responsive photonic crystals with bistable states for low-power electrophoretic color displays

Electrically responsive photonic crystals are promising materials for electrophoretic color displays with better brightness and color saturation. However, electric field must always be applied to maintain the specific colors, which brings concerns about the power consumption and signal stability and reversibility. Here, we show an electrically responsive photonic crystal with two stable states at 0 V, which are the colored state or the colorless state with ordered or disordered particle arrangement. The color state can be reversibly switched by applying a short-time electrical field, just like in the case of commercial electrophoretic ink. With optimized recipe and electric field, the photonic crystals encapsulated in the prototype display panel are proved to have potentials in high resolution, multi-color, and greyscale display, which lays down a firm basis for reflective displays with low power consumption and good visibility.

A bioinspired, electroactive colorable and additive manufactured photonic artificial muscle

Structural coloration in biomimetic nanostructures has remarkable application potential in vivid display devices, but their color change effect is still insufficiently competitive towards biology. Inspired by the feather color change of a hummingbird, a new methodology for coloration is proposed. A structure-colorable flexural artificial muscle (FlexAM) is developed by integrating a view-angle dependent photonic diffraction grating pattern and voltage-actuated dielectric elastomers as an electroactive entity via laminated object additive manufacturing. A multi-physics model is developed which guides the FlexAM to harness the view-angle dependence for the new coloration strategy. The electro-mechanochromic performances are experimentally characterized to verify the prediction of the multi-physics model. An ultrafast coloration in the FlexAM with an advancing figure-of-merit at a color-shift rate of 2.814 nm ms^-1 is realized, in addition to an excellent fatigue resistance up to 10 000 cycles. A photonic display with arrayed FlexAM elements is designed, which can be used to display numbers and letters. The current research offers an advanced artificial muscle towards active photonic and visible strain sensing.