Graphene-oxide/TiO₂ nanocomposite films with electron-donors for multicolor holography

Graphene oxide (GO) with an ideal two-dimensional structure, presents outstanding optical, electric, and mechanical properties which draws great attention in advanced information devices. Recently, GO-based films were found to show photochromic behavior, especially for the TiO₂ involved system which has potential data processing capability, such as storing holograms. However, expanding spectral response range and increasing exposure sensitivity are still challenges for such a film, due to the limited photo-quantum efficiency in reduction reaction. Here, an innovative method of "Immersion-Dropping" technology is proposed to fabricate GO-based continuous films. We, for the first time, achieve colored holography from violet to yellow regions on GO/TiO₂ nanocomposite films with introduction of weak acid molecules. A "diffraction self-enhancement" is observed. The obtained results benefit from the broadband photo-response of weak acid molecules and photo-triggered transferring of electrons in multi-channels. This work provides a research strategy for the large-capacity information storage and colorful display device.