We have investigated centrifuge effect on the poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (denote PEDOT/ PSS) films prepared by a spin-coating coupled with a solvent-treatment, by a dynamic light scattering, a scanning transmission electron microscopic, an atomic force microscopic, and ultraviolet-visible spectroscopic measurements, in terms of electrical conductivity and optical transmittance. As a result, we have successfully prepared highly conductive (443 S/cm) and transparent (89%) PEDOT/PSS thin films with thickness of 93 nm by the combination of three approaches, i.e., centrifuge, spin-coating and solvent-treatment.KEY WORDS: Conductive Polymer / PEDOT/PSS / Thin Film / Transparent Electrode / Colloidal Dispersion / Since the ''solubility'' was realized by using a water-soluble polyelectrolyte poly(4-styrenesulfonate) (PSS), 1 poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT/PSS) has been extensively studied from viewpoints of academic and technologic aspects.2-5 The PEDOT/PSS has been a widely available conductive polymer since the colloidal dispersion of the PEDOT/PSS in water could easily provide films on various substrates by simple means such as solution casting and spincoating techniques.Recently we have reported correlation between sizes of colloidal particles and minimum thickness of spin-coated thin films of PEDOT/PSS studied by a dynamic light scattering (DLS), a scanning transmission electron microscopy coupled with an energy dispersive X-ray spectroscopy (STEM-EDX), C 60 -sputtering X-ray photoelectron spectroscopy (XPS), and an atomic force microscopy (AFM).6 As a result, PEDOT/PSS thin films spin-coated at 3000 rpm, are suggested to be primary nanoparticle-''monolayer''s, based on the results of STEM-EDX, DLS, and XPS measurements. The AFM and conductive-probe microscopic images revealed that the PEDOT/PSS primary nanoparticles do not packed compactly within the thin films. Such thin films showed high transparency but poor conductivity.Principally PSS-layer-removed PEDOT/PSS nanoparticles with narrow size distributions would result in compactly packed nanoparticle-thin films which can be expected to show both high conductivity and transparency.Herein we present significant enhancement on electrical conductivity of spin-coated PEDOT-PSS thin films by centrifuge and solvent effects, while high transparency maintained. The PEDOT/PSS thin film with 93-nm thickness showed electrical conductivity of 443 S/cm and visible lighttransmittance of 89%. EXPERIMENTAL 20 mL of PEDOT/PSS (BAYTRON PH500) solution was separated by a centrifuge at 4000-5000 rpm and the upper layer of the solution was decanted. The upper layered solution was freeze-dried to obtain PEDOT/ PSS powder. The powder was re-dispersed in deionized water under ultrasonication, resulting in PEDOT/PSS solution with a concentration of 2 wt %. 9 mL of the 2 wt % solution with or without ethyleneglycol (EG) was dropped on the silicon wafer. The spin-coatings were performed at rotation speed of 3000 rpm for 1 mi...

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A strontium titanate (SrTiO3) thin film on a heavily doped n-type silicon wafer prepared by sputtering was characterized by various means. The result indicated that the thin film mainly consisted of an 87-nm-thick amorphous SrTiO3 with a Sr:Ti:O ratio of 1:1.3:4.7, a dielectric constant of ε r=12.1, and a leakage current density of 0.2 nA/cm2 at an electric field of 1 MV/cm. Pentacene field-effect transistors fabricated using the SrTiO3 thin film as an insulator, showed well-saturated output characteristics at low driving voltages (V D=-3 V), and a hole mobility of 0.08 cm2 V-1 s-1, an on/off current ratio of 104, and threshold voltage of -0.7 V.

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