TY - JOUR
T1 - Quantum-Chemical Evaluation of Impact of Chlorination versus Fluorination on the Electronic Properties of Donors and Acceptors for Organic Solar Cells
AU - Wang, Tonghui
AU - Brédas, Jean Luc
N1 - Funding Information:
This work has been supported by the Office of Naval Research in the framework of Award No. N00014‐17‐1‐2208, as well as by the Georgia Institute of Technology.
Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Much attention is given to replacing fluorine with chlorine when optimizing the chemical structures of π-conjugated polymer donors and/or non-fullerene small-molecule acceptors (SMAs) in order to reduce the synthetic costs for large-scale applications of organic solar cells. To rationalize the impact of chlorination versus fluorination on the electronic properties of π-conjugated materials, quantum-mechanical calculations have generally been carried out at the global-hybrid becke three-parameter Lee-Yang-Parr (B3LYP) level of theory. However, B3LYP suffers from drawbacks that are especially problematic in the case of π-conjugated systems possessing a charge-transfer character. Here, the dipole moments and energy levels of F- and Cl-containing SMA fragments, that is, 1,2-difluorobenzene and 1,2-dichlorobenzene, are reevaluated at much more robust levels of theory. The results obtained with the (optimally tuned) long-range corrected ωB97XD functional (coming from Head-Gordon and coworkers and including dispersion corrections) turn out very close to those calculated with the “gold-standard” CCSD(T) (coupled-custer with single, double, and perturbative triple excitations) method. These results, however, both markedly differ from the B3LYP findings. This confirms that, for π-conjugated systems, tuned long-range corrected functionals provide a reasonable compromise between accuracy and computational cost, and that much caution must be exerted when using the popular B3LYP functional.
AB - Much attention is given to replacing fluorine with chlorine when optimizing the chemical structures of π-conjugated polymer donors and/or non-fullerene small-molecule acceptors (SMAs) in order to reduce the synthetic costs for large-scale applications of organic solar cells. To rationalize the impact of chlorination versus fluorination on the electronic properties of π-conjugated materials, quantum-mechanical calculations have generally been carried out at the global-hybrid becke three-parameter Lee-Yang-Parr (B3LYP) level of theory. However, B3LYP suffers from drawbacks that are especially problematic in the case of π-conjugated systems possessing a charge-transfer character. Here, the dipole moments and energy levels of F- and Cl-containing SMA fragments, that is, 1,2-difluorobenzene and 1,2-dichlorobenzene, are reevaluated at much more robust levels of theory. The results obtained with the (optimally tuned) long-range corrected ωB97XD functional (coming from Head-Gordon and coworkers and including dispersion corrections) turn out very close to those calculated with the “gold-standard” CCSD(T) (coupled-custer with single, double, and perturbative triple excitations) method. These results, however, both markedly differ from the B3LYP findings. This confirms that, for π-conjugated systems, tuned long-range corrected functionals provide a reasonable compromise between accuracy and computational cost, and that much caution must be exerted when using the popular B3LYP functional.
KW - CCSD(T) calculations
KW - chlorination
KW - density functional theory calculations
KW - fluorination
KW - organic solar cells
KW - π-conjugated materials
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U2 - 10.1002/adts.201900136
DO - 10.1002/adts.201900136
M3 - Article
AN - SCOPUS:85089034462
SN - 2513-0390
VL - 2
JO - Advanced Theory and Simulations
JF - Advanced Theory and Simulations
IS - 12
M1 - 1900136
ER -