Surface plasmon spectroscopy of thin composite films of Au nanoparticles and PEDOT:PSS conjugated polymer

We studied the effect of Au nanoparticles (NPs) on optical properties of composite films of poly(3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) mixed with Au NPs of 20, 40 and 60 nm in diameter by surface plasmon resonance (SPR) spectroscopy. The excitation wavelength of SPR redshifts with increasing the concentration of Au NPs in the Au/PEDOT:PSS composite films. The SPR spectra were simulated by using transfer matrix method (TMM) and effective medium approximation (EMA). The SPR wavelength redshift was ascribed to the film thickness increase of Au/PEDOT:PSS composites rather than effective permittivity variation of the composite films induced with Au NPs inclusion.