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Frederic Laquai - One of the best experts on this subject based on the ideXlab platform.
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
Journal of Physical Chemistry C, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation...
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
The Journal of Physical Chemistry, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation. We observe the population of high-lying “dark” excited states following ET from the donor to the acceptor. The “dark” states successively undergo CT and form CT states of higher energy, with decreased recombination rates, while maintaining the high charge generation efficiency. Changes in CT reaction rates are rationalized within the Marcus theory, with driving forces and reorganization energies evaluated by density functional theory and polarizable continuum models. The present study demonstrates the importance of energetically higher-lying states, which cannot be directly photoexcited yet are accessible through ET from local excited states. Similar processes are anticipated in other donor–acceptor systems, which allow for both energy and CT processes, such as bulk heterojunctions of the polymer and small-molecule donor/nonfullerene acceptor typically used in photovoltaic systems.
Denis Andrienko - One of the best experts on this subject based on the ideXlab platform.
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
Journal of Physical Chemistry C, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation...
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
The Journal of Physical Chemistry, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation. We observe the population of high-lying “dark” excited states following ET from the donor to the acceptor. The “dark” states successively undergo CT and form CT states of higher energy, with decreased recombination rates, while maintaining the high charge generation efficiency. Changes in CT reaction rates are rationalized within the Marcus theory, with driving forces and reorganization energies evaluated by density functional theory and polarizable continuum models. The present study demonstrates the importance of energetically higher-lying states, which cannot be directly photoexcited yet are accessible through ET from local excited states. Similar processes are anticipated in other donor–acceptor systems, which allow for both energy and CT processes, such as bulk heterojunctions of the polymer and small-molecule donor/nonfullerene acceptor typically used in photovoltaic systems.
Ahmed H Balawi - One of the best experts on this subject based on the ideXlab platform.
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
Journal of Physical Chemistry C, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation...
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
The Journal of Physical Chemistry, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation. We observe the population of high-lying “dark” excited states following ET from the donor to the acceptor. The “dark” states successively undergo CT and form CT states of higher energy, with decreased recombination rates, while maintaining the high charge generation efficiency. Changes in CT reaction rates are rationalized within the Marcus theory, with driving forces and reorganization energies evaluated by density functional theory and polarizable continuum models. The present study demonstrates the importance of energetically higher-lying states, which cannot be directly photoexcited yet are accessible through ET from local excited states. Similar processes are anticipated in other donor–acceptor systems, which allow for both energy and CT processes, such as bulk heterojunctions of the polymer and small-molecule donor/nonfullerene acceptor typically used in photovoltaic systems.
David S. Ginger - One of the best experts on this subject based on the ideXlab platform.
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imaging charge transfer state excitations in polymer fullerene solar cells with time resolved electrostatic force microscopy
Journal of Physical Chemistry Letters, 2015Co-Authors: Micah S Glaz, Jeffrey S Harrison, Samuel R. Peurifoy, David C. Coffey, David S. GingerAbstract:We demonstrate nanoscale imaging of charge transfer state Photoexcitations in polymer/fullerene bulk heterojunction solar cells using time-resolved electrostatic force microscopy (trEFM). We compare local trEFM charging rates and external quantum efficiencies (EQE) for both above-gap and below-gap excitation of the model system poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). We show that the local trEFM charging rate correlates with device EQE for both above-gap and below-gap Photoexcitation, demonstrating that EFM methods have sufficient sensitivity to detect the low EQEs associated with CT state formation, a result that could be useful for probing weak subgap excitations in nanostructured materials such as quantum dot and organometal halide perovskite solar cells. Further, we use trEFM to map spatial variations in EQE arising from subgap CT excitation in organic photovoltaics (OPVs) and find that the local distribution of...
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Imaging Charge Transfer State Excitations in Polymer/Fullerene Solar Cells with Time-Resolved Electrostatic Force Microscopy.
Journal of Physical Chemistry Letters, 2015Co-Authors: Micah S Glaz, Jeffrey S Harrison, Samuel R. Peurifoy, David C. Coffey, David S. GingerAbstract:We demonstrate nanoscale imaging of charge transfer state Photoexcitations in polymer/fullerene bulk heterojunction solar cells using time-resolved electrostatic force microscopy (trEFM). We compare local trEFM charging rates and external quantum efficiencies (EQE) for both above-gap and below-gap excitation of the model system poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). We show that the local trEFM charging rate correlates with device EQE for both above-gap and below-gap Photoexcitation, demonstrating that EFM methods have sufficient sensitivity to detect the low EQEs associated with CT state formation, a result that could be useful for probing weak subgap excitations in nanostructured materials such as quantum dot and organometal halide perovskite solar cells. Further, we use trEFM to map spatial variations in EQE arising from subgap CT excitation in organic photovoltaics (OPVs) and find that the local distribution of...
Sebastian Stappert - One of the best experts on this subject based on the ideXlab platform.
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
Journal of Physical Chemistry C, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation...
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direct and energy transfer mediated charge transfer state formation and recombination in triangulene spacer perylenediimide multichromophores lessons for photovoltaic applications
The Journal of Physical Chemistry, 2019Co-Authors: Ahmed H Balawi, Sebastian Stappert, Julien Gorenflot, Chen Li, Klaus Mullen, Denis Andrienko, Frederic LaquaiAbstract:We study the dynamics of primary Photoexcitations in three symmetric donor–spacer–acceptor–spacer–donor multichromophores with increasing oligophenylene spacer length, following selective donor or acceptor excitation. Energy levels of the donor and acceptor moieties are tailored to facilitate splitting of the excited state into a lower-lying charge-transfer (CT) state, mimicking the functionality of a donor–acceptor interface for charge generation, thus resulting in long-lived charge separation. Ultrafast electronic energy transfer (ET) from the donor followed by fast hole (back)transfer from the acceptor populates the molecules’ CT states. However, the CT efficiency is found to be close to unity, independent of the donor or acceptor Photoexcitation. The ratio of CT and recombination rates, which reflects the population of CT states, increases with the oligophenylene spacer length for both direct hole transfer and hole transfer following ET, boosting the population of CT states under continuous excitation. We observe the population of high-lying “dark” excited states following ET from the donor to the acceptor. The “dark” states successively undergo CT and form CT states of higher energy, with decreased recombination rates, while maintaining the high charge generation efficiency. Changes in CT reaction rates are rationalized within the Marcus theory, with driving forces and reorganization energies evaluated by density functional theory and polarizable continuum models. The present study demonstrates the importance of energetically higher-lying states, which cannot be directly photoexcited yet are accessible through ET from local excited states. Similar processes are anticipated in other donor–acceptor systems, which allow for both energy and CT processes, such as bulk heterojunctions of the polymer and small-molecule donor/nonfullerene acceptor typically used in photovoltaic systems.
