|
|||||
|
|
Electronic structure and optical properties of isolated and TiO2-grafted free base porphyrins for water oxidation: A challenging test case for DFT and TD-DFT |
|
| Authors: | Syrine Daoudi Abderrahmane Semmeq Michael Badawi Xavier Assfeld Youssef Arfaoui Mariachiara Pastore |
| Institution: | 1. CNRS & Université de Lorraine, Laboratoire de Physique et Chimie Théoriques, Boulevard des Aiguillettes, BP, 70239 54506 Vandoeuvre-lès-Nancy Cedex, France
Laboratory of Physical Chemistry of Condensed Materials, Faculty of Mathematical, Physical and Natural Sciences of Tunis, University of Tunis El Manar, Campus Farhat-Hached, 1068 Tunis, Tunisia;2. CNRS & Université de Lorraine, Laboratoire de Physique et Chimie Théoriques, Boulevard des Aiguillettes, BP, 70239 54506 Vandoeuvre-lès-Nancy Cedex, France Laboratoire Physique de la Matière Condensée, Faculté des Sciences Ben M'sik, Université Hassan II de Casablanca, Casablanca, Morocco;3. CNRS & Université de Lorraine, Laboratoire de Physique et Chimie Théoriques, Boulevard des Aiguillettes, BP, 70239 54506 Vandoeuvre-lès-Nancy Cedex, France;4. Laboratory of Physical Chemistry of Condensed Materials, Faculty of Mathematical, Physical and Natural Sciences of Tunis, University of Tunis El Manar, Campus Farhat-Hached, 1068 Tunis, Tunisia |
| Abstract: | Seven free base porphyrins employed in dye-sensitized photoelectrosynthetic cells are investigated with the aim of benchmarking the ability of different density functional theory (DFT) and time-dependent DFT approaches in reproducing their structure, vertical, and E0-0 excitation energies and the energy levels alignment (red-ox properties) at the interface with the TiO2. We find that both vertical and E0-0 excitation energies are accurately reproduced by range-separated functionals, among which the ω B97X-D delivers the lowest absolute deviations from experiments. When the dye/TiO2 interface is modeled, the physical interfacial energetics is only obtained when the B3LYP functional is employed; on the other hand, M06-2X (54% of exchange) and the two long-range corrected approaches tested (CAM-B3LYP and ω B97X-D) excessively destabilize the semiconductor conduction band levels with respect to the dye's lowest unoccupied molecular orbitals (LUMOs), predicting no pathway for electron injection. © 2019 Wiley Periodicals, Inc. |
| Keywords: | DFT TDDFT free base porphrins dye sensitized TiO2 water splitting |