On the Molecular Origin of Charge Separation at the Donor–Acceptor Interface

Gjergji Sini, Marcel Schubert, Chad Risko, Steffen Roland, Olivia P. Lee, Zhihua Chen, Thomas V. Richter, Daniel Dolfen, Veaceslav Coropceanu, Sabine Ludwigs, Ullrich Scherf, Antonio Facchetti, Jean M.J. Fréchet, Dieter Neher

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Fullerene-based acceptors have dominated organic solar cells for almost two decades. It is only within the last few years that alternative acceptors rival their dominance, introducing much more flexibility in the optoelectronic properties of these material blends. However, a fundamental physical understanding of the processes that drive charge separation at organic heterojunctions is still missing, but urgently needed to direct further material improvements. Here a combined experimental and theoretical approach is used to understand the intimate mechanisms by which molecular structure contributes to exciton dissociation, charge separation, and charge recombination at the donor–acceptor (D–A) interface. Model systems comprised of polythiophene-based donor and rylene diimide-based acceptor polymers are used and a detailed density functional theory (DFT) investigation is performed. The results point to the roles that geometric deformations and direct-contact intermolecular polarization play in establishing a driving force (energy gradient) for the optoelectronic processes taking place at the interface. A substantial impact for this driving force is found to stem from polymer deformations at the interface, a finding that can clearly lead to new design approaches in the development of the next generation of conjugated polymers and small molecules.

Original languageEnglish
Article number1702232
JournalAdvanced Energy Materials
Issue number12
StatePublished - Apr 25 2018

Bibliographical note

Publisher Copyright:
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • donor–acceptor interfaces
  • energy gradients
  • geometrical deformations
  • nonfullerene acceptors
  • organic photovoltaics
  • photocurrent generation
  • polymer solar cells

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Materials Science


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