Tuning the Interfacial Electronic Structure at Organic Heterojunctions by Chemical Design.
Quantum-chemical techniques are applied to assess the electronic structure at donor/acceptor heterojunctions of interest for organic solar cells. We show that electrostatic effects at the interface of model 1D stacks profoundly modify the energy landscape explored by charge carriers in the photoconversion process and that these can be tuned by chemical design. When fullerene C60 molecules are used as acceptors and unsubstituted oligothiophenes or pentacene are used as donors, the uncompensated quadrupolar electric field at the interface provides the driving force for splitting of the charge-transfer states into free charges. This quadrupolar field can be either enhanced by switching from a C60 to a perylene-tetracarboxylic-dianhydride (PTCDA) acceptor or suppressed by grafting electron-withdrawing groups on the donor.
†Université de Bordeaux, Institut des Sciences Moléculaires, 351 Cours de la Libération, F-33405 Talence CEDEX.|‡Service de Chimie des Matériaux Nouveaux, Université de Mons, Place du Parc 20, B-7000 Mons, Belgium.
Sébastien
S
Mothy
‡Service de Chimie des Matériaux Nouveaux, Université de Mons, Place du Parc 20, B-7000 Mons, Belgium.
Maxime
M
Guillaume
†Université de Bordeaux, Institut des Sciences Moléculaires, 351 Cours de la Libération, F-33405 Talence CEDEX.|‡Service de Chimie des Matériaux Nouveaux, Université de Mons, Place du Parc 20, B-7000 Mons, Belgium.
Julien
J
Idé
†Université de Bordeaux, Institut des Sciences Moléculaires, 351 Cours de la Libération, F-33405 Talence CEDEX.
Frédéric
F
Castet
†Université de Bordeaux, Institut des Sciences Moléculaires, 351 Cours de la Libération, F-33405 Talence CEDEX.
Laurent
L
Ducasse
‡Service de Chimie des Matériaux Nouveaux, Université de Mons, Place du Parc 20, B-7000 Mons, Belgium.
Jérôme
J
Cornil
‡Service de Chimie des Matériaux Nouveaux, Université de Mons, Place du Parc 20, B-7000 Mons, Belgium.
David
D
Beljonne
band bending effect; exciton dissociation; molecular modeling; organic solar cells; quadrupolar electric field