The electrical and optical properties of thin layers of nano-sized antimony doped tinoxide particles

For the use in anti-static films on glass or polymeric substrates, transpar ent conductive layers can be prepared by spinning an aqueous suspension of nano-sized antimony-doped tinoxide (ATO) particles. These layers have a res istivity which is substantially higher than that of homogeneous ATO layers which are deposited by physical vapour deposition techniques. By curing the films to temperatures up to 700 degrees C, the resistivity of the particle layer can be decreased by two or three decades. Because the nano-sized par ticles are prepared by a low-temperature process a different mechanism can contribute to this decrease in resistivity. Possible effects which may infl uence the conductivity are sintering of the particles, change of the bulk m aterial and the presence of an insulating layer at the outside of the parti cles. This decrease can be explained by the presence of an insulating antim ony-rich layer on the outside of the particles, the thickness of which is r educed when the layer is cured. At temperatures above 350 degrees C, sinter ing of the particles also highly influences the decrease in resistivity. At temperatures above 700 degrees C, the resistivity is increased due to segr egation of the antimony to the surface of the particle. (C) 1999 Kluwer Aca demic Publishers.