A high-contrast complementary electrochromic device based on polyaniline (PANI) tethered polyhedral oligomeric silsesquioxane (POSS) (POSS-PANI) and poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonic acid) (PEDOT:PSS) is assembled. The electrochromic properties, cyclic voltammetry behavior and coloration efficiency of the device are studied. Due to the loosely packed structure, POSS-PANI gives rise to a significantly higher electrochromic contrast, coloration efficiency and faster switching speed than PANI. Despite its high contrast, the combination of POSS-PANI with PEDOT:PSS still shows synergy in terms of contrast enhancement, which can be attributed to the additional driving force for the diffusion of dopants into PEDOT:PSS provided by the dedoping of POSS-PANI. (C) 2009 Elsevier B.V. All rights reserved.