Biomimetic thermally responsive photonic crystals film with highly robust by introducing thermochromic dyes

Thermally responsive photonic crystals (TRPCs) are intelligent responsive materials that can dynamically coordinate electromagnetic wave transmission, translating thermal stimuli into optical signals and structural color changes. However, it remains a big challenge to develop a robust TRPC, because of the thermochromic mechanism of unstable dramatic volume change that collapses photonic crystal (PC) structure. We demonstrate a highly robust and flexible TRPC film inspired by the chameleon, combining thermochromic dyes (TDs) with PC for a synergistic response. There is only negligible color fluctuation even after 2000 color-change cycles, attributing to no lattice parameter change during the thermal stimulus. Moreover, both positive (transparency to opaque color) and negative (opaque color to transparency) TDs are introduced into TRPC, implementing a full-color RGB thermally-responsive system. The response of the positive-TRPC and negative-TRPC temperatures were 32.0 and 50.5 °C, respectively. A TRPC film with environmental adaptability was designed, which offers a promising route to anti-counterfeiting, steganography and smart window.