TY - JOUR
T1 - Molecular packing of non-fullerene acceptors for organic solar cells
T2 - Distinctive local morphology in Y6 vs. ITIC derivatives
AU - Kupgan, G.
AU - Chen, X. K.
AU - Brédas, J. L.
N1 - Funding Information:
This work was supported by the Department of the Navy, Office of Naval Research (Award No. N00014-20-1-2110). The authors thank the DOD High Performance Computing Modernization Program as well as the Advanced Computing Environment (PACE) at the Georgia Institute of Technology for computational resources. The authors are most grateful to Dr. Veaceslav Coropceanu and Dr. Tonghui Wang for stimulating discussions.
Funding Information:
This work was supported by the Department of the Navy , Office of Naval Research (Award No. N00014-20-1-2110). The authors thank the DOD High Performance Computing Modernization Program as well as the Advanced Computing Environment (PACE) at the Georgia Institute of Technology for computational resources. The authors are most grateful to Dr. Veaceslav Coropceanu and Dr. Tonghui Wang for stimulating discussions.
Publisher Copyright:
© 2021 The Authors
PY - 2021/9
Y1 - 2021/9
N2 - Since a couple of years ago, Y6 has emerged as one of the main non-fullerene acceptors for organic solar cells, as its use leads to superior power conversion efficiencies. It is thus of major interest to investigate the multiscale phenomena that are responsible for Y6's efficacy. Here, we modeled neat films of Y6 and earlier non-fullerene acceptors, IT-4F and ITIC, using a combination of density functional theory calculations and molecular dynamics simulations, to investigate the various factors that control their charge and exciton transport rates. We find that the molecular packing in Y6 is drastically different from that in IT-4F and ITIC. At the nanoscale, the local morphology of Y6 consists of a large number of directional face-on stackings and well-connected transport networks. Y6 also consistently shows higher electronic couplings for LUMOs, HOMOs, and local excitations than ITIC-type acceptors, which results in fast transport rates for electrons, holes, and excitons. Importantly, when considering dimers, their configurations in Y6 are more diverse than in ITIC-type acceptors, with many of those similar to the configurations observed in the Y6 crystal structure reported recently. Most Y6 dimer configurations exhibit strong binding interactions, large electronic couplings, and high transport rates, which when taken together rationalize the better performance of OSCs based on Y6.
AB - Since a couple of years ago, Y6 has emerged as one of the main non-fullerene acceptors for organic solar cells, as its use leads to superior power conversion efficiencies. It is thus of major interest to investigate the multiscale phenomena that are responsible for Y6's efficacy. Here, we modeled neat films of Y6 and earlier non-fullerene acceptors, IT-4F and ITIC, using a combination of density functional theory calculations and molecular dynamics simulations, to investigate the various factors that control their charge and exciton transport rates. We find that the molecular packing in Y6 is drastically different from that in IT-4F and ITIC. At the nanoscale, the local morphology of Y6 consists of a large number of directional face-on stackings and well-connected transport networks. Y6 also consistently shows higher electronic couplings for LUMOs, HOMOs, and local excitations than ITIC-type acceptors, which results in fast transport rates for electrons, holes, and excitons. Importantly, when considering dimers, their configurations in Y6 are more diverse than in ITIC-type acceptors, with many of those similar to the configurations observed in the Y6 crystal structure reported recently. Most Y6 dimer configurations exhibit strong binding interactions, large electronic couplings, and high transport rates, which when taken together rationalize the better performance of OSCs based on Y6.
KW - Density functional theory
KW - Electronic couplings
KW - Molecular dynamics
KW - Packing configurations
KW - Transport rates
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U2 - 10.1016/j.mtadv.2021.100154
DO - 10.1016/j.mtadv.2021.100154
M3 - Article
AN - SCOPUS:85110341945
SN - 2590-0498
VL - 11
JO - Materials Today Advances
JF - Materials Today Advances
M1 - 100154
ER -