Modeling optoelectronic properties of metal free porphyrins used in dye sensitized photoelectrosynthetic cells

8^th European Chemistry Congress

June 21-23, 2018 | Paris, France

Syrine Daoud, Xavier Assfeld, Mariachiara Pastore and Youssef Arfaoui

University of Lorraine, France

Posters & Accepted Abstracts: Chem Sci J

Abstract :

Solar energy conversion and storage by photoelectrochemical water splitting has garnered significant research attention in recent years. Nowadays, much attention has been paid to the development of dye sensitized photoelectrochemical cells (DS-PECs), because of their low cost of production and high energy-conversion efficiency. DS-PECs (Figure 1) are based on the configurations of dye-sensitized solar cells (DSCs), but with the aim to drive the two half reactions of water splitting at two physically separated compartments (electrodes) rather than to generate electrical power. The sensitizers containing expensive ruthenium atoms and having weak absorption in the near-IR region have limitations in view of large scale industrial production, thus Ruthenium-free sensitizers such as porphyrins and phthalocyanines have become promising alternatives in DS-PECs. In the present work, we examine the ground and excited state properties of a series of porphyrins and compare them to the experimental data with the aim of setting up a computational framework able to accurately reproduce both the optical and redox properties of these compounds. We investigate the ability of various DFT functionals in predicting vertical and adiabatic excitation energies as well as ground and excited state oxidation potentials (GSOP and ESOP, respectively). We show that while of the optical absorption properties are an overall well described by the tested functionals, the calculated values for the redox potentials, requiring the calculations of gas phase oxidation free energies and solvation energies for the neutral and oxidized species, do not always follow a coherent trend within the set of molecules. The present results highlight, therefore, the challenging task of accurately predict the redox properties of metal free-sensitizers by state-of-the-art DFT methodologies, Figure 1. Schematic diagram of a dye-sensitized photoelectrochemical cell (DS-PEC) for lightdriven water oxidation and proton reduction.

Biography :

Syrine is a second-year PhD student at University of Lorraine and University of Tunis El Manar with interdisciplinary research interests at the intersection of molecular modeling and theoretical chemistry. Her research is focused particularly on the mechanism in water splitting dye sensitized photoelechtochemical cells, the efficiency of these solar cells, the optical and redox properties of series metal free organic sensitizers “the porphyrins”. Prior to arriving at nancy, she graduated a master’s degree in organic chemistry at university of Tunis El Manar. She has published one paper in MOJ drug design development & therapy journal. She participated to the doctoral school day SESAMES with a poster and to the 7th organic chemistry days in Hammamet Tunis with oral communication.

E-mail: syrine.daoudi@univ-lorraine.fr