Direct Observation of Structure and Dynamics of Photogenerated Charge Carriers in Poly(3-hexylthiophene) Films by Femtosecond Time-Resolved Near-IR Inverse Raman Spectroscopy

Tomohisa Takaya, Ippei Enokida, Yukio Furukawa, Koichi Iwata

    Research output: Contribution to journalArticle

    Abstract

    The initial charge separation process of conjugated polymers is one of the key factors for understanding their conductivity. The structure of photogenerated transients in conjugated polymers can be observed by resonance Raman spectroscopy in the near-IR region because they exhibit characteristic low-energy transitions. Here, we investigate the structure and dynamics of photogenerated transients in a regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend film, as well as in a pristine P3HT film, using femtosecond time-resolved resonance inverse Raman spectroscopy in the near-IR region. The transient inverse Raman spectrum of the pristine P3HT film at 50 ps suggests coexistence of neutral and charged excitations, whereas that of the P3HT:PCBM blend film at 50 ps suggests formation of positive polarons with a different structure from those in an FeCl3-doped P3HT film. Time-resolved near-IR inverse Raman spectra of the blend film clearly show the absence of charge separation between P3HT and PCBM within the instrument response time of our spectrometer, while they indicate two independent pathways of the polaron formation with time constants of 0.3 and 10 ps.

    Original languageEnglish
    Article number431
    JournalMolecules
    Volume24
    Issue number3
    DOIs
    Publication statusPublished - 2019 Jan 1

    Fingerprint

    Raman Spectrum Analysis
    Charge carriers
    Raman spectroscopy
    charge carriers
    Observation
    butyric acid
    esters
    Butyric Acid
    Conjugated polymers
    polarization (charge separation)
    Raman scattering
    Polymers
    Esters
    Raman spectra
    Gene Conversion
    Polarons
    polymers
    polarons
    time constant
    Reaction Time

    Keywords

    • Bulk heterojunction
    • Conjugated polymer
    • Femtosecond inverse Raman spectroscopy
    • Polaron

    ASJC Scopus subject areas

    • Analytical Chemistry
    • Chemistry (miscellaneous)
    • Molecular Medicine
    • Pharmaceutical Science
    • Drug Discovery
    • Physical and Theoretical Chemistry
    • Organic Chemistry

    Cite this

    Direct Observation of Structure and Dynamics of Photogenerated Charge Carriers in Poly(3-hexylthiophene) Films by Femtosecond Time-Resolved Near-IR Inverse Raman Spectroscopy. / Takaya, Tomohisa; Enokida, Ippei; Furukawa, Yukio; Iwata, Koichi.

    In: Molecules, Vol. 24, No. 3, 431, 01.01.2019.

    Research output: Contribution to journalArticle

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