Tunable pure interference colors of 2D titania liquid crystal with ultrasensitive electroresponse

Electrochromic effect refers to the electrically tunable coloration of a matter. Emerging see-through color-tunable applications pose a synergetic demand on electrochromic device, concurrently having ultralow field driving, operation in transmissive mode, and high-purity and tunable interference colors of sci-fi perception. However, such an electrochromic device remains elusive. Herein, we invent a transmissive electro-interference-color device based on two-dimensional titania liquid crystals (2D TiO₂ LCs), demonstrating a record-high electroresponse sensitivity of ~1.5 × 10^-7 square meters per square volt among all wide-bandgap media. Consequently, the device works under an electric field of 6 × 10³ volts per meter (three orders of magnitude lower than that of conventional LCs), operates in a transmissive mode with ~85% transparency, and displays pure and tunable interference colors. The electro-interference-color device serves as a good example to fabricate diverse see-through chromatic applications as conceptually demonstrated smart windows with functions of privacy protection, energy saving, and artistic presentation as well as transparent display.