[nanoPost] Photochromic thin films

University France

Photochromic and thermochromic films: Photochromic glasses used for example as ophthalmic glasses can be viewed as a collection of small (10nm) silver halide crystals doped with specific ions and suspended in an inert glass matrix. It is well-known that these glasses darken under UV irradiation by formation of colloidal particles of metallic silver. Photochromic glasses are prepared by conventional melting techniques at very high temperature (>1000°C). After casting, glasses are annealed at lower temperatures (<600°C) in order to in-situ generate doped silver halide nanocrystals. By using such a technique it is very difficult to control nanocrystal concentration and to prepare thin film (1-100µm) on very specific substrates (polymer).

The use of wet colloidal routes to prepare photosensitive nanoparticles (metallic halide based nanocrystals with specific composition) and sol-gel technique to produce hybrid organic-inorganic matrices has great potential in photochromic material design and preparation. They can be obtained in any desired shape, including thin films.