Electrochromic properties of functional squarylium dyes

The electrochromic properties of some squarylium dye (SQ) were studied by using BuOH/CH2Cl2(4:6/v:v) solution with Bu4NClO4 as supporting electrolyte. The electrochromic display(ECD) cell of these squarylium dyes coloured blue in open-circuit condition, but changed to a green colour at 1.41 similar to 1.8 volt, At an applied voltage in the range higher than 2.1 volt, the absorbance at 480 nm and 630 nm decreases vapidly and the reversible colour change in open-circuit condition disappeared. The cyclic voltametric behaviour of the dyes was investigated and the first and second oxidation potentials measured. Decolouration rates in open-circuit were found to be first-order processes. (C) 1997 Elsevier Science Ltd.