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-TiO2-A, which is based on electron-transfer processes involving a molecular sensitizer (S) and an electron acceptor (A) coadsorbed onto the surface of nanocrystalline TiO2. 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.