Structural Color‐Based Smart Liquid Windows Address the Tradeoff Between High Optical Transparency and Brilliant Color

Abstract It is challenging for traditional smart windows to possess both high optical transparency (90%, 380–780 nm) and brilliant colors since they are usually contradictory to each other. Here, novel liquid thermal‐responsive smart windows (TSWs) exhibiting high optical transparency (94%), bright iridescent forward scattering structural color, and extremely weak reflective structural colors are fabricated by constructing a refractive index (RI)‐matched non‐close‐packing ordered structure with large lattice distances and thus unique light diffraction mechanisms. The transmittance (24‐94%) and dual‐mode structural color saturation (1–55 times) can be dynamically regulated by simply altering temperatures (20–100 °C), which can be attributed to the temperature‐dependent light diffraction and scattering efficiency. A new information encryption‐decryption technique is developed by combining TSWs with outstanding shapeability, recyclability, and flowability. The information is hidden under normal conditions, while 76 different pieces of information can be decrypted in programmable ways under different stimuli, showing their potential in anti‐counterfeiting and information encryption.