The photoluminescence emission spectrum at low temperature of the TiO2 anatase shows a broad band around 2.3 eV that has been largely attributed to self-trapped excitons. In a new paper published in Physical Review B, we use time-resolved experiments conducted at low temperature on a thin layer and a single crystal to give insights into the carrier dynamics inside TiO2. The decay of the photoluminescence with time can be described by a single power law from the picoseconds time range up to the milliseconds time range. The decay rate increases with increasing temperature. We propose to interpret these observations by a collision mechanism between self-trapped excitons that diffuse via hopping processes. These excitons, which are stabilized by the indirect band gap of anatase TiO2, can be ionized at higher temperatures and lead thus to an acceleration of the observed dynamics. These results were obtained in the frame of the PhD work of Adrien Girault and in collaboration with the institute of physics and chemistry of materials in Strasbourg (IPCMS).

Photocarrier dynamics in anatase TiO2: Evidence of thermally activated collisions between carriers

Adrien Girault^1,2,3, Mathieu Gallart¹, Marc Ziegler ¹, Olivier Crégut¹, Matteo Balestrieri³, Iryna Gozhyk³, Hervé Montigaud³, Davide Sciacca², Lorenzo Mancini², and Pierre Gilliot ¹

1. IPCMS UMR 7504, CNRS, Université de Strasbourg, 23 rue du Loess, Boîte Postale 43, F-67034 Strasbourg CEDEX 2, France
2. Saint-Gobain Research Paris, 39 quai Lucien Lefranc, F-93303 Aubervilliers CEDEX, France
3. Laboratoire “Surface du Verre et Interfaces” UMR 125 Saint-Gobain, CNRS, 39 quai Lucien Lefranc, F-93303 Aubervilliers CEDEX, France

Physical Review B 2023 Vol. 108 Issue 15 Pages 155204

DOI: 10.1103/PhysRevB.108.155204

https://link.aps.org/doi/10.1103/PhysRevB.108.155204