Characteristics of dual-type electrochromic device based on poly(3-tetradecylthiophene) and poly (3,4-ethylenedioxythiophene)

Two single- and a dual-type electrochromic devices (ECDs) based on poly(3-tetradecylthiophene) (PTDT) and poly(3,4-ethylenedioxythiophene) (PEDOT) with lithium salt in PMMA gel-media were prepared. In the single-type ECDs, red PTDT (lambda(max): 494 nm) and blue PEDOT (lambda(max): 596 nm) in the reduced states could be switched to their bleached oxidized forms. In the dual-type ECD, the color changed between dark red 502 nm) and dark blue (lambda(max): 602 nm) by switching the applied voltage (E(PTDT) versus E(PEDOT)) between -2.2 and 2.2 V Its electronic absorption was a combination of those of PTDT and PEDOT. Its optical switching rate was much faster than the single-type ECDs. It is presumably because the capacitive charging of each bare ITO electrode in the single-type ECDs partially compensates the applied voltage while in the dual-type ECD, both the electrodes participate in the faradaic reactions. In this dual-type ECD, when one of the electrodes takes part in coloring electrode, the other takes part in complementary electrode leading to fast switching. (C) 2003 Elsevier B.V. All rights reserved.