TY  - JOUR
A1  - Sini, Gjergji
A1  - Schubert, Marcel
A1  - Risko, Chad
A1  - Roland, Steffen
A1  - Lee, Olivia P.
A1  - Chen, Zhihua
A1  - Richter, Thomas V.
A1  - Dolfen, Daniel
A1  - Coropceanu, Veaceslav
A1  - Ludwigs, Sabine
A1  - Scherf, Ullrich
A1  - Facchetti, Antonio
A1  - Frechet, Jean M. J.
A1  - Neher, Dieter
T1  - On the Molecular Origin of Charge Separation at the Donor-Acceptor Interface
JF  - Advanced energy materials
N2  - 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.
KW  - donor-acceptor interfaces
KW  - energy gradients
KW  - geometrical deformations
KW  - nonfullerene acceptors
KW  - organic photovoltaics
KW  - photocurrent generation
KW  - polymer solar cells
Y1  - 2018
U6  - https://doi.org/10.1002/aenm.201702232
SN  - 1614-6832
SN  - 1614-6840
VL  - 8
IS  - 12
PB  - Wiley-VCH
CY  - Weinheim
ER  -