Physical insights into the photoactivated ullmann coupling process producing highly conjugated oligothiophene films on a copper substrate

Sudarshan Natarajan, Guangming Liu, Seong Kim

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

This paper describes the details of surface reactions producing > 100-nm-thick conjugated- polymer films. When 2,5-diiodothiophene films deposited on copper are irradiated with UV at room temperature in Ar environments, oligothiophene films are synthesized. The average conjugation length of the produced film varies from ∼7 to 3-4 as the film thickness increases from ∼100 to ∼500 nm. The X-ray photoelectron spectroscopy analysis of the produced films reveals evidence for the formation of organo-copper intermediate species at the copper-monomer film interface and their diffusion from the copper surface into the monomer film during the photochemical process. A one-dimensional diffusion-reaction model is presented to explain the formation, diffusion, and reaction of organo-copper intermediates in the multilayer film during the photochemical reaction. The model simulation results qualitatively explain the decrease of the Ullmann coupling contribution in the photochemical reaction with the film thickness.

Original languageEnglish (US)
Pages (from-to)8047-8051
Number of pages5
JournalJournal of Physical Chemistry B
Volume110
Issue number15
DOIs
StatePublished - Apr 20 2006

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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