Fast switching electrochromic display using a viologen-modified ZnO nanowire array electrode

We report an electrochromic (EC) display using a viologen-modified ZnO nanowire array as the EC electrode. The ZnO nanowire array was grown directly on an indium tin oxide (ITO) glass by a low temperature aqueous thermal decomposition method and then modified with viologen molecules. The ZnO nanowire electrochromic device shows fast switching time (170 and 142 ms for coloration and bleaching respectively for a 1 cm(2) cell), high coloration efficiency (196 C-1 cm(2)) and good stability. The improved performance of the ZnO nanowires EC device can be attributed to the large surface area and high crystalline and good electron transport properties of the ZnO nanowire array.