Electrochromism of Highly Doped Nanocrystalline SnO2:Sb

The electrochromic effect of layers of nanocrystalline tin dioxide highly doped with antimony has been investigated in detail, using chronoamperometry, cyclic voltammetry, potential-dependent IR spectroscopy and UV−vis spectroscopy. It is shown that two different mechanisms are responsible for the color changes observed upon negative polarization of porous SnO2:Sb nanocrystal layers. Injection of electrons via the back contact increases the plasma absorption of the material, which has its maximum intensity in the near-infrared region. This increase is accompanied by a strong increase of the electrical conductivity of the layer, indicating that the grain boundary potentials of the nanoparticle layer decrease at negative potentials applied. In the presence of small ions such as Li+ or in protic electrolytes such as water, insertion of Li+ and H+ takes place, resulting in an additional color change mainly in the visible. The rate of the color changes is mainly determined by the conductivity of the substrate....