Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells

Sean M. Ryno; Yao Tsung Fu; Chad Risko; Jean Luc Brédas

doi:10.1021/acsami.6b02851

Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells

Sean M. Ryno, Yao Tsung Fu, Chad Risko, Jean Luc Brédas

Research output: Contribution to journal › Article › peer-review

32 Scopus citations

Abstract

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.

Original language	English
Pages (from-to)	15524-15534
Number of pages	11
Journal	ACS Applied Materials and Interfaces
Volume	8
Issue number	24
DOIs	https://doi.org/10.1021/acsami.6b02851
State	Published - Jun 22 2016

Bibliographical note

Funding Information:
This work has been supported by King Abdullah University of Science and Technology (KAUST), the KAUST Competitive Research Grant program, and the Office of Naval Research Global (Award N62909-15-1-2003). We acknowledge the IT Research Computing Team and Supercomputing Laboratory at KAUST for providing computational and storage resources. This work has also used the computing resources of the Garnet, Spirit, and Copper supercomputing systems through the DoD HPCMP. C.R. thanks the University of Kentucky Vice President of Research for start-up funds. We wish to thank Mahesh Kumar Ravva and Naga Rajesh Tummala for stimulating discussions and assistance with technical elements of the molecular dynamics simulations.

Publisher Copyright:
© 2016 American Chemical Society.

Keywords

charge separation and recombination
energetic disorder
molecular dynamics
multiscale modeling
organic photovoltaics
organic-organic interfaces
polarization

ASJC Scopus subject areas

Materials Science (all)

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10.1021/acsami.6b02851

Cite this

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title = "Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells",

abstract = "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.",

keywords = "charge separation and recombination, energetic disorder, molecular dynamics, multiscale modeling, organic photovoltaics, organic-organic interfaces, polarization",

author = "Ryno, {Sean M.} and Fu, {Yao Tsung} and Chad Risko and Br{\'e}das, {Jean Luc}",

note = "Funding Information: This work has been supported by King Abdullah University of Science and Technology (KAUST), the KAUST Competitive Research Grant program, and the Office of Naval Research Global (Award N62909-15-1-2003). We acknowledge the IT Research Computing Team and Supercomputing Laboratory at KAUST for providing computational and storage resources. This work has also used the computing resources of the Garnet, Spirit, and Copper supercomputing systems through the DoD HPCMP. C.R. thanks the University of Kentucky Vice President of Research for start-up funds. We wish to thank Mahesh Kumar Ravva and Naga Rajesh Tummala for stimulating discussions and assistance with technical elements of the molecular dynamics simulations. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

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AU - Fu, Yao Tsung

AU - Risko, Chad

AU - Brédas, Jean Luc

N1 - Funding Information: This work has been supported by King Abdullah University of Science and Technology (KAUST), the KAUST Competitive Research Grant program, and the Office of Naval Research Global (Award N62909-15-1-2003). We acknowledge the IT Research Computing Team and Supercomputing Laboratory at KAUST for providing computational and storage resources. This work has also used the computing resources of the Garnet, Spirit, and Copper supercomputing systems through the DoD HPCMP. C.R. thanks the University of Kentucky Vice President of Research for start-up funds. We wish to thank Mahesh Kumar Ravva and Naga Rajesh Tummala for stimulating discussions and assistance with technical elements of the molecular dynamics simulations. Publisher Copyright: © 2016 American Chemical Society.

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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.

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Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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