On the Molecular Origin of Charge Separation at the Donor–Acceptor Interface
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 22, 2018
- Source ID
- 10.1002/aenm.201702232
Entities
People
- Antonio Facchetti
- Chad Risko
- Daniel Dolfen
- Dieter Neher
- Gjergji Sini
- Jean Fréchet
- Marcel Schubert
- Olivia P. Lee
- Sabine Ludwigs
- Steffen Roland
- Thomas V. Richter
- Ullrich Scherf
- Veaceslav Coropceanu
- Zhihua Chen
Organizations
- Cergy-Pontoise University
- Georgia Tech
- King Abdullah University of Science and Technology
- Northwestern University
- Office of Naval Research
- United States Navy
- University of Kentucky
- University of Potsdam
- University of St Andrews
- University of Wuppertal
- Yusuf Hamied Department of Chemistry