Solid-State Photochromic Device Based on Nanocrystalline TiO2 Functionalized with Electron Donor−Acceptor Species

In this Communication, we report on a new type of solid-state photochromic device, S-TiO(2)-A, which is based on electron-transfer processes involving a molecular sensitizer (S) and an electron acceptor (A) coadsorbed onto the surface of nanocrystalline TiO(2). The electron-transfer process is mediated by the semiconductor conduction band and leads to a long-lived charge-separated state S(+)/A(-). The lifetime of this state can be controlled by oxygen diffusion through a polymeric coating deposited on the device.