Terahertz complex conductivity of stretchable semitransparent composite films made from polymeric materials PDMS and PEDOT:PSS

We investigate the terahertz complex conductivity spectra of stretchable composite films with semitransparency for visible light that are fabricated by blending the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with the elastomer poly(dimethylsiloxane) (PDMS) in various weight ratios. We find that the PDMS-based composite exhibits a conductivity whose real part increases to 0.77 S/cm at 1.0 THz with increasing PEDOT:PSS blending ratio while it has a stretchability of more than ∼130%. A fitting analysis of the complex conductivity spectra with an extended Drude model shows that carriers in the PDMS-based composite become denser linearly and also less localized gradually as the blending ratio is increased.