The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Troy Van Voorhis - One of the best experts on this subject based on the ideXlab platform.

  • spin dependent Charge Transfer State design rules in organic photovoltaics
    Nature Communications, 2015
    Co-Authors: Wendi Chang, Matthias E. Bahlke, Daniel N Congreve, Eric Hontz, David Paul Mcmahon, Sebastian Reineke, Tony Wu, Vladimir Bulovic, Troy Van Voorhis
    Abstract:

    An important source of loss in solar cells is the recombination of the photogenerated Charge carriers before they are extracted from the device. Chang et al. now show that such recombination can be reduced in organic solar cells by increasing the separation between donors and acceptors.

  • Charge Transfer State Versus Hot Exciton Dissociation in Polymer−Fullerene Blended Solar Cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Koen Vandewal, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer−fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current−voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  • Charge Transfer State versus hot exciton dissociation in polymer-fullerene blended solar cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Jiye Lee, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, Koen Vandewal, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer-fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current-voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

J. V. Manca - One of the best experts on this subject based on the ideXlab platform.

  • Charge Transfer State Versus Hot Exciton Dissociation in Polymer−Fullerene Blended Solar Cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Koen Vandewal, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer−fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current−voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  • Charge Transfer State versus hot exciton dissociation in polymer-fullerene blended solar cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Jiye Lee, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, Koen Vandewal, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer-fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current-voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  • varying polymer crystallinity in nanofiber poly 3 alkylthiophene pcbm solar cells influence on Charge Transfer State energy and open circuit voltage
    Applied Physics Letters, 2009
    Co-Authors: Koen Vandewal, Wibren D Oosterbaan, Sabine Bertho, Veerle Vrindts, Abay Gadisa, Laurence Lutsen, Dirk Vanderzande, J. V. Manca
    Abstract:

    The effect of poly(3-alkylthiophene) (P3AT) crystallinity in (nanofiber P3AT):PCBM photovoltaic devices on the energy of the Charge-Transfer State (ECT) and on the open-circuit voltage (Voc) is investigated for poly(3-butythiophene), poly(3-pentylthiophene) and poly(3-hexylhiophene). P3AT crystallinity, expressed as the crystalline nanofiber mass fraction f to the total P3AT mass in the spin-coating dispersion, is varied between ∼0.1 and ∼0.9 by temperature control. ECT, as obtained by Fourier-transform photocurrent spectroscopy decreased with f as ECT=ECT0−0.2f eV. Alkyl side-chain length only influences ECT0. Voc relates to ECT as Voc=ECT/q−0.6 V.

Koen Vandewal - One of the best experts on this subject based on the ideXlab platform.

  • Charge Transfer State Versus Hot Exciton Dissociation in Polymer−Fullerene Blended Solar Cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Koen Vandewal, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer−fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current−voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  • Charge Transfer State versus hot exciton dissociation in polymer-fullerene blended solar cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Jiye Lee, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, Koen Vandewal, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer-fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current-voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  • varying polymer crystallinity in nanofiber poly 3 alkylthiophene pcbm solar cells influence on Charge Transfer State energy and open circuit voltage
    Applied Physics Letters, 2009
    Co-Authors: Koen Vandewal, Wibren D Oosterbaan, Sabine Bertho, Veerle Vrindts, Abay Gadisa, Laurence Lutsen, Dirk Vanderzande, J. V. Manca
    Abstract:

    The effect of poly(3-alkylthiophene) (P3AT) crystallinity in (nanofiber P3AT):PCBM photovoltaic devices on the energy of the Charge-Transfer State (ECT) and on the open-circuit voltage (Voc) is investigated for poly(3-butythiophene), poly(3-pentylthiophene) and poly(3-hexylhiophene). P3AT crystallinity, expressed as the crystalline nanofiber mass fraction f to the total P3AT mass in the spin-coating dispersion, is varied between ∼0.1 and ∼0.9 by temperature control. ECT, as obtained by Fourier-transform photocurrent spectroscopy decreased with f as ECT=ECT0−0.2f eV. Alkyl side-chain length only influences ECT0. Voc relates to ECT as Voc=ECT/q−0.6 V.

Matthias E. Bahlke - One of the best experts on this subject based on the ideXlab platform.

  • spin dependent Charge Transfer State design rules in organic photovoltaics
    Nature Communications, 2015
    Co-Authors: Wendi Chang, Matthias E. Bahlke, Daniel N Congreve, Eric Hontz, David Paul Mcmahon, Sebastian Reineke, Tony Wu, Vladimir Bulovic, Troy Van Voorhis
    Abstract:

    An important source of loss in solar cells is the recombination of the photogenerated Charge carriers before they are extracted from the device. Chang et al. now show that such recombination can be reduced in organic solar cells by increasing the separation between donors and acceptors.

  • Charge Transfer State Versus Hot Exciton Dissociation in Polymer−Fullerene Blended Solar Cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Koen Vandewal, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer−fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current−voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  • Charge Transfer State versus hot exciton dissociation in polymer-fullerene blended solar cells
    Journal of the American Chemical Society, 2010
    Co-Authors: Jiye Lee, Ludwig Goris, J. V. Manca, Matthias E. Bahlke, Shane R. Yost, Koen Vandewal, M. Antonietta Baldo, Troy Van Voorhis
    Abstract:

    We examine the significance of hot exciton dissociation in two archetypical polymer-fullerene blend solar cells. Rather than evolving through a bound Charge Transfer State, hot processes are proposed to convert excitons directly into free Charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of Charge Transfer States. The internal quantum yield, together with the temperature dependence of the current-voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

David S Ginger - One of the best experts on this subject based on the ideXlab platform.

  • imaging Charge Transfer State excitations in polymer fullerene solar cells with time resolved electrostatic force microscopy
    Journal of Physical Chemistry Letters, 2015
    Co-Authors: Micah S Glaz, Jeffrey S Harrison, Samuel R Peurifoy, David C Coffey, David S Ginger
    Abstract:

    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...

  • Imaging Charge Transfer State Excitations in Polymer/Fullerene Solar Cells with Time-Resolved Electrostatic Force Microscopy.
    Journal of Physical Chemistry Letters, 2015
    Co-Authors: Micah S Glaz, Jeffrey S Harrison, Samuel R Peurifoy, David C Coffey, David S Ginger
    Abstract:

    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...