Modification of Ionization Potential of Poly(ethylene dioxythiophene):Poly(styrene sulfonate) Film by Acid or Base Treatment

概要

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We studied the effects of surface treatments on the surface electronic state of the poly(3,4-ethylene dioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) film. The surface treatments performed were immersion of the PEDOT:PSS film in an acid or base solution, and the exposure of the PEDOT:PSS film to acid or base vapor. The ionization potential ($I_{\text{p}}$) of the PEDOT:PSS film is modified between 4.5 and 5.3 eV by surface treatments. $I_{\text{p}}$ tends to be increased by acid treatment, although it tends to be decreased by base treatment. Because $I_{\text{p}}$ is modified even by brief treatments, the modification is thought to result from surface condition changes. Measurements using X-ray photoelectron spectroscopy (XPS), resistivity, and optical absorbance revealed that an electric double layer might have been formed on the surface of the PEDOT:PSS film by the treatment. The electric double layer shifts the vacuum level. Assuming the formation of an electric double layer, we can describe $I_{\text{p}}$ modification by the treatment.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2007-11-15