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, poly3,4ethylenedioxythiophenePEDOT and heptyl viologen HVBF42, were utilized to fabricate a hybrid electrochromic device ECD. PEDOT and HVBF42 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 T of 20% at 610 nm was observed in the first stage 0.5 to 0.8 V, whereas a maximum 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