Letter abstract
Nature Materials 2, 29 - 31 (2002)
Published online: 15 December 2002 | doi:10.1038/nmat796
Subject Categories: Optical, photonic and optoelectronic materials | Surface and thin films
Multicolour photochromism of TiO2 films loaded with silver nanoparticles
Yoshihisa Ohko1,2, Tetsu Tatsuma3, Tsuyoshi Fujii1, Kenji Naoi1, Chisa Niwa4, Yoshinobu Kubota5 & Akira Fujishima1
Photochromic materials, which change their colours reversibly in response to light, can be applied to smart windows, displays and memories1, 2, 3. Conventional photochromic materials respond in a monochromatic way, so that multicolour photochromism has required several different materials or filters combined appropriately. If multicolour photochromism could be achieved with a simple material, photochromic devices would be find a greater number of applications, including a rewritable colour copy paper or electronic paper4 and a high-density multi-wavelength optical memory. Here we report multicolour photochromism of TiO2 films loaded with silver nanoparticles by photocatalytic means. Its colour, initially brownish-grey, changes under monochromatic visible light to almost the same colour as that of the light; the apparently uniform Ag–TiO2 film can be almost any colour. Behaviour similar to persistent hole-burning effects5, 6 is also observed. The colour reverts to brownish-grey under ultraviolet light, and these processes are repeatable.
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Corporation (JST), 4-1-8 Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
- Kanagawa Academy of Science and Technology, KSP Bldg. East 412, 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012, Japan
- Department of Urology, School of Medicine, University of Yokohama City, 3-9 Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa 236-0004, Japan
Correspondence to: Akira Fujishima1 e-mail: akira-fu@fchem.chem.t.u-tokyo.ac.jp
