Full-Color Scattering Based on Plasmon and Mie Resonances of Gold Nanoparticles Modulated by Fabry–Pérot Interference for Coloring and Image Projection

Plasmonic coloring of bulk materials has been based mostly on light absorption of metal nanoparticles. However, relatively large plasmonic nanoparticles also show unique scattering colors. Such scattering nanoparticles have been applied to dichroic and multichromatic materials. Among plasmonic materials, silver nanoparticles are suitable for full-color absorption and scattering. Even so, their stability is not necessarily sufficient for practical use, in particular when those are in contact with a semiconductor such as TiO2, which is often used as a highly dielectric material. Although gold nanoparticles are more stable, those do not exhibit plasmon resonance in the blue color range. In this study, we achieved full-color scattering from gold nanoparticles by the aid of Mie scattering. Gold nanoparticles with a sufficient size were deposited on a thin TiO2 layer, and their blue, green, and red scattering based on nonplasmonic Mie resonance, plasmonic full-surface mode, and plasmonic interface mode, respectively, were modulated on the basis of Fabry–Pérot interference by changing the TiO2 thickness. The full-color scattering films would be used for anticounterfeiting. Their additional applications include a transparent projection screen. It looks almost transparent under ambient light, but full-color images can be displayed on the screen by a projector. The present materials are suitable for large-area applications because they are easy to be prepared through a chemical bottom-up technique.