A High Contrast Hybrid Electrochromic Device Containing PEDOT, Heptyl Viologen, and Radical Provider TEMPO

An anodic radical provider, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and two electrochromic (EC) materials, poly(3,4-ethylenedioxythiophene) (PEDOT) and heptyl viologen [HV(BF4)(2)], were utilized to fabricate a hybrid electrochromic device (ECD). PEDOT and HV(BF4)(2) were used as film and solution-type cathodic EC materials, respectively. The ECD exhibited two-stage redox reactions with high absorbance attenuation in the visible region. With the variation in the operating voltage, a maximum transmittance change (Delta T) of 20% at 610 nm was observed in the first stage (-0.5 to 0.8 V), whereas a maximum Delta T of 68% was observed in the second stage (0.8-1.5 V). Furthermore, fast switching times of 6.9 and 2.1 s were estimated for bleaching and darkening, respectively. The coloration efficiencies at 610 nm were 171.9 and 91.0 cm(2) C-1 for the first and second stages, respectively. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3428711] All rights reserved.