TY - JOUR
T1 - Polarization Energies at Organic-Organic Interfaces
T2 - Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells
AU - Ryno, Sean M.
AU - Fu, Yao Tsung
AU - Risko, Chad
AU - Brédas, Jean Luc
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/6/22
Y1 - 2016/6/22
N2 - We probe the energetic landscape at a model pentacene/fullerene (C60) interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e., the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges results in a barrier to charge separation at the pentacene/C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.
AB - We probe the energetic landscape at a model pentacene/fullerene (C60) interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e., the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges results in a barrier to charge separation at the pentacene/C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.
KW - charge separation and recombination
KW - energetic disorder
KW - molecular dynamics
KW - multiscale modeling
KW - organic photovoltaics
KW - organic-organic interfaces
KW - polarization
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U2 - 10.1021/acsami.6b02851
DO - 10.1021/acsami.6b02851
M3 - Article
AN - SCOPUS:84976388599
SN - 1944-8244
VL - 8
SP - 15524
EP - 15534
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 24
ER -