AC electrical properties of conjugated polymers and theoretical high-frequency behavior of multilayer films

AC electrical properties of various conjugated polymers such as emeraldine base form of polyaniline, polyacetylene derivatives, and poly(1,4-phenylenevinylene) and its derivative are studied. Dielectric constant and conductivity are measured in the frequency range from 10 Hz to 2 MHz and in the temperature range from 78 to 300 K. Frequency dependence of ac dielectric constant follows Debye or Cole–Cole dielectric relaxation equation, and temperature dependence of relaxation time τ follows Arrhenius equation τ=τ0 exp(Ea/kBT). Frequency dependence of ac conductivity shows a constant behavior in low-frequency regime (≤10 kHz) and a power-law behavior (σ∼ωs) in high-frequency regime (≥100 kHz). For the applications of multilayer films of conducting polymers such as electromagnetic interference (EMI) shielding or optical filter, we theoretically calculate the reflectance, absorbance, and EMI shielding efficiency in high-frequency range (≥1 GHz) based on plane wave theory.