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Imaging Charge Localization in a Conjugated Oligophenylene.

Laerte L Patera1, Fabian Queck1, Jascha Repp1

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Physical Review Letters
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Summary
This summary is machine-generated.

Excess charge injection in oligophenylenes causes self-trapping, localizing the charge and inducing structural changes. This study reveals the interplay between charge localization and molecular conformation in conjugated polymers.

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Area of Science:

  • Materials Science
  • Physical Chemistry
  • Organic Electronics

Background:

  • Polaron formation significantly impacts conjugated polymers' optical and electronic properties.
  • Molecular conformation in polyphenylene arises from electron delocalization and steric interactions.
  • Excess charge injection is hypothesized to enhance conjugation and cause structural distortions.

Purpose of the Study:

  • Investigate the effect of excess charge on individual oligophenylene molecules at the single-molecule level.
  • Characterize structural and electronic changes upon hole injection in oligophenylenes.
  • Understand the role of charge self-trapping in conjugated systems.

Main Methods:

  • Utilized sub-molecular-resolved atomic force microscopy (AFM).
  • Employed redox-state-selective orbital imaging techniques.
  • Studied individual oligophenylene molecules on sodium chloride films.

Main Results:

  • Observed charge localization in the cationic radical state of oligophenylene.
  • Demonstrated partial planarization of the molecule upon hole injection.
  • Characterized the delocalized frontier orbital in the neutral molecule.

Conclusions:

  • Provided direct evidence for charge self-trapping in oligophenylenes.
  • Highlighted the significant interplay between charge localization and structural distortion.
  • Offered insights into the fundamental behavior of charge carriers in conjugated polymers.