AMADEus Seminar - Towards the microscopic modeling of organic light-emitting devices - Wednesday 19 November 2014, 04:30 pm - ICMCBle 19/11 à 16h30
Part I: Thermally Activated Delayed Fluorescence in organic emitters: a molecular picture
Juan-Carlos Sancho-García (email@example.com)
Departamento de Química Física
Universidad de Alicante, Spain
Abstract: New materials for OLED applications with low singlet-triplet energy splitting have been recently synthesized in order to allow for the e?cient conversion of triplet into singlet excitons (emitting light) via a Thermally Activated Delayed Fluorescence (TADF) process. Accurately predicting this singlet-triplet energy splitting is key to the understanding and further design of organic materials, but the prediction which may be hampered by the charge-transfer nature of the states involved [1,2]. The accurate modeling of these states with Time-Dependent Density Functional Theory (TD-DFT) is thus highly challenging, and possible insights might be masked by routine drawbacks of the calculations . We will thus address this issue by carefully examining how to systematically reduce as much as possible the underlying error bar of any calculation, before presenting next a qualitative correlation between the experimental singlet-triplet values and a metrics used to measure the extent of that charge-transfer .
 J. Aragó, J. C. Sancho-García, E. Ortí, and D. Beljonne, J. Chem. Theory Comput. 7 (2011), 2068.
 F. Di Meo, P. Trouillas, C. Adamo, and J. C. Sancho-García, J. Chem. Phys. 139 (2013), 64104
 J. C. Sancho-García and C. Adamo, Phys. Chem. Chem. Phys. 15 (2013), 14581.
 M. Moral-Muñoz, L. Muccioli, W.-J. Son, Y. Olivier, and J. C. Sancho-García, J. Chem. Theory Comput., submitted (2014)
Part II: Computing charge transport properties in organic semiconductors:
insights from molecular modeling at different length scales
Dr. Yoann Olivier (firstname.lastname@example.org)
Laboratory for Chemistry of Novel Materials
University of Mons, Belgium
Abstract: Improving the charge carrier mobility in organic-based devices such as LEDs, solar cells and FETs is of crucial importance in order to achieve standardized performances. To reach this objective, a detailed understanding at the molecular scale of the influence of structural organization on the charge carrier mobility is a key issue. In disordered materials, the hopping regime is a reliable model to depict charge transport. In this framework, charge transport has often been described using the semi-classical Marcus theory, with the main parameters - transfer integral and reorganization energy - calculated with quantum chemistry . In this contribution, we will highlight by means of molecular modeling the subtle interplay between the molecular organization and charge transport properties. By combining quantum-chemical methods, molecular dynamics and Monte Carlo simulations, we will show different examples going from crystalline  to disordered organic semiconductors such as liquid-crystalline  and polymeric materials  with special attention on the potential lessons learnt for further design of materials with improved charge transport properties.
 V. Coropceanu, J. Cornil, D.A. da Silva Filho, Y. Olivier, R. Silbey, J. L. Brédas, Chem. Rev. 107 (2007), 926.
 F. Oton, R. Pfattner, E. Pavlica, Y. Olivier, E. Moreno, J. Puigdollers, G. Bratina, J. Cornil, X. Fontrodona, M. Mas-Torrent, J. Veciana, and C. Rovira. Chem. Mater. 23 (2011), 851.
 Y. Olivier, L. Muccioli, V. Lemaur, Y. H. Geerts, C. Zannoni, and J. Cornil, J. Phys. Chem. B 113 (2009), 14102.
 V. Lemaur, L. Muccioli, C. Zannoni, D. Beljonne, R. Lazzaroni, J. Cornil, and Y. Olivier. Macromolecules 46 (2013), 8171; Y. Olivier, D. Niedzalek, V. Lemaur, W. Pisula, K. Müllen, U. Koldemir, J. Reynolds, R. Lazzaroni, J. Cornil, and D. Beljonne. Adv. Mat. 26 (2014), 2119.