Transparent and flexible phosphomolybdate–agarose composite thin films with visible-light photochromism

Abstract

Polyoxometalates (POMs) are promising photochromic materials, but flexible POM-based thin films sensitive to visible-light have not been reported so far. In this study, highly transparent flexible self-supporting phosphomolybdate(PMo₁₂)–agarose thin films were successfully fabricated by the combination of hydrogel chemistry and a facile casting technique. It was identified that strong interaction between polyhydroxyl site of agarose and PMo₁₂ by hydrogen bonds together with densely-packed 3D network structure in the gel state avoided the phase separation efficiently and resulted in the homogenous distribution of PMo₁₂ as well as the good mechanical properties of the nanocomposite films. More importantly, the obtained thin films exhibited excellent visible-light photochromic performance. When exposed to blue light irradiation through a TEM copper grid as photomask, the image recorded on the film displayed good resolution at 2 μm scale. Therefore, the developed PMo₁₂–agarose photochromic thin films are promising for applications in portable high-resolution displays and high-density memory devices.