Organic Semiconductors: A Molecular Picture of the Charge-Transport and Energy-Transport Processes.

Conjugated organic oligomer and polymer materials are being increasingly considered for their incorporation as the active semiconductor elements in devices such as photo-voltaic cells, light-emitting diodes, or field-effects transistors. In the operation of these devices, electron-transfer and energy-transfer processes play a key role, for instance in the form of charge transport (in the bulk or across interfaces), energy transport, charge separation, or charge recombination [1]. Here, we provide a theoretical description of electron-transfer phenomena based on electron-transfer theory, which allows us to provide a molecular, chemically-oriented understanding. In this presentation, we focus on the parameters that impact the mobility of charge carriers [2], that is the electronic coupling within chains and between adjacent chains and the reorganization energy of the chains upon ionization. Materials under study include conjugated oligomers such as oligoacenes, oligothiophene-acenes, oligothiophenes, and oligothienacenes. \newline \newline [1] J.L. Br\'{e}das, D. Beljonne, V. Coropceanu, and J. Cornil, ``Charge-Transfer and Energy-Transfer Processes in pi-Conjugated Oligomers and Polymers'', Chemical Reviews, 104, 4971-5004 (2004). \newline [2] V. Coropceanu, J. Cornil, D.A. da Silva Filho, Y. Olivier, R. Silbey, and J.L. Br\'{e}das, ``Charge Transport in Organic Semiconductors'', Chemical Reviews, 107, xxx (2007).