| 초록 |
Addition of solvent additive, dimethylsulfoxide (DMSO), to an aqueous solution of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) can increase dc conductivity of PEDOT:PSS films dramatically. To investigate this effect, we performed optical reflectance measurements on these films over a wide spectral range (0.01-0.62 eV) and data were analyzed by Kramers-Kronig (KK) transformation. In contrast with significant increase in dc conductivity (1.5 S/cm → 700 S/cm), identical plasma frequency around 1.1 eV for both films of aqueous solutions with and without DMSO was observed, indicating that the free-charge concentration of PEDOT:PSS film is not influenced by addition of DMSO. Meanwhile, the value of optical conductivity, σ(ω), extrapolated to zero frequency is in good agreement with dc conductivity of each film. To understand the effect of DMSO on PEDOT:PSS film, further detailed analysis was performed in terms of the “localization-modified Drude (LMD) model”. |
