Charge carrier photogeneration and recombination in ladder-type poly(para-phenylene): Interplay between impurities and external electric field

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Abstract

Charge carrier generation and decay in m-LPPP polymer films were examined by means of femtosecond transient absorption spectroscopy in the time window of 100 fs-15 ns. Two modes of polaron formation with distinct behavior were identified, impurity induced in the absence of an external electric field and electric field induced in pristine film. While field induced charge generation is relatively slow, occurring throughout the excited state lifetime, the rate of impurity induced charge generation is much faster and depends on excitation wavelength; it occurs on the several hundred femtosecond time scale under excitation within the main absorption band, but excitation into the red wing of the absorption band results in charge generation within less than 100 fs. Polaron decay through geminate electron-hole recombination occurs with widely distributed lifetimes, from similar to 0.8 ns to microseconds; the polarons characterized by the shortest decay time have a redshifted absorption spectrum (as compared to more long-lived polarons) and are attributed to tightly bound polaron pairs.

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  • Atom and Molecular Physics and Optics
Original languageEnglish
Article number235203
JournalPhysical Review B (Condensed Matter and Materials Physics)
Volume76
Issue number23
Publication statusPublished - 2007
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Chemical Physics (S) (011001060)