Ultrafast electronic processes at semiconductor polymer heterojunctions: A molecular-level, quantum-dynamical analysis

I. Burghardt, E. R. Bittner, Hiroyuki Tamura

    Research output: Contribution to journalConference articlepeer-review

    1 Citation (Scopus)

    Abstract

    This contribution gives an overview of our recent study of phonon driven exciton dissociation at semiconductor polymer heterojunctions, using a quantum dynamical analysis based on a linear vibronic coupling model parametrized for three electronic states and 20-30 phonon modes. The decay of the photogenerated exciton towards an interfacial charge transfer state is an ultrafast (femtosecond to picosecond scale) process which initiates the photocurrent generation. We consider several representative interface configurations, which are shown to exhibit an efficient exciton dissociation. The process depends critically on the presence of intermediate states, and on the dynamical interplay between high-frequency (C=C stretch) and low-frequency (ring-torsional) modes. The dynamical mechanism is interpreted in terms of a hierarchical electron-phonon model which allows one to identify generalized reaction coordinates for the nonadiabatic process. This analysis highlights that the electron-phonon coupling is dominated by the high-frequency modes, but the low-frequency modes are crucial in mediating the transition to a charge-separated state. The ultra-fast, highly nonequilibrium dynamics is in accordance with spectroscopic observations.

    Original languageEnglish
    Pages (from-to)138-143
    Number of pages6
    JournalAIP Conference Proceedings
    Volume1102
    DOIs
    Publication statusPublished - 2009 May 12
    EventTheory and Applications of Computational Chemistry, TACC 2008 - Shanghai, China
    Duration: 2008 Sep 232008 Sep 27

    Keywords

    • Excitons
    • Optoelectronics
    • Semiconducting polymer materials
    • Vibronic coupling

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Fingerprint Dive into the research topics of 'Ultrafast electronic processes at semiconductor polymer heterojunctions: A molecular-level, quantum-dynamical analysis'. Together they form a unique fingerprint.

    Cite this