Kinetics of TiO photochromic response in different hole scavenging solvents.

There has recently been a renewed interest in the photochromic properties and uses of TiO as a potential candidate for smart windows. However, the surrounding medium of TiO nanoparticles (NPs) is of equal importance, as it facilitates hole scavenging and, in turn, photochromism. Here, we investigated the impact of scavenging power on the photochromic properties of TiO. TiO NP colloids in these solvents exhibit a photochromic response in a broad wavelength range from the visible to near-infrared region. We have shown that solvents such as ethanol have the best hole scavenging properties among the alcohols tested. The response can be further modified by the addition of a supplementary hole scavenger, such as hydroxylamine. The photochromism of TiO is fully reversible and could be used for applications in smart windows.