Electrochromic properties of poly(3,4‐ethylenedioxythiophene) nanocomposite film containing SiO 2 nanoparticles

Through incorporation of SiO 2 nanoparticles (NPs) into poly(3,4‐ethylenedioxythiophene) (PEDOT) films, the physical volume effect of nanoparticles on the electrochromic properties of PEDOT was investigated. PEDOT‐SiO 2 nanocomposite thin films were prepared using SiO 2 NPs, 3,4‐ethylenedioxythiophene (EDOT), iron p ‐toluenesulfonate and an imidazole mixture. During incorporation, SiO 2 NPs agglomerated to form a cluster, which affected the surface roughness of PEDOT films. Photoemission spectroscopic results of C 1s and S 2p show that incorporated SiO 2 NPs did not chemically interact but heavily affect the conjugation length and packing density of PEDOT due to a physical volume effect. This physical effect of SiO 2 NPs resulted in enhanced electrical conductivity of PEDOT and induced a blue shift of the maximum absorption peak in ultra violet‐visible spectroscopic analysis. Also, a gradual enhancement in the electrochromic properties of PEDOT was obtained by increasing the amount of SiO 2 NPs; in particular, the switching speed of PEDOT reduced from 3.34 s to 1.28 s with incorporation of 10 wt % SiO 2 NPs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011