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

Sean Ryno; Yao-Tsung Fu; Chad Risko; Jean-Luc Bredas

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 Ryno, Yao-Tsung Fu, Chad Risko, Jean-Luc Bredas

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

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): N62909-15-1-2003
Acknowledgements: 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.

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10.1021/acsami.6b02851

https://repository.kaust.edu.sa/bitstream/10754/611771/1/acsami2E6b02851.pdf

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.",

author = "Sean Ryno and Yao-Tsung Fu and Chad Risko and Jean-Luc Bredas",

note = "KAUST Repository Item: Exported on 2020-10-01 Acknowledged KAUST grant number(s): N62909-15-1-2003 Acknowledgements: 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.",

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AU - Bredas, Jean-Luc

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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

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