Influence of polyvinylpyrrolidone on properties of flexible electrically conducting indium tin oxide nanoparticle coatings

The influence of the organic film agent polyvinylpyrrolidone (PVP) on the electrical conductivity of indium tin oxide (ITO) nanoparticle coatings on polyethyleneterephthalate films was investigated. The ITO/PVP nanocomposite coatings show a decrease of the specific resistance with increasing PVP content up to 40 vol.%, whereas for higher PVP contents the specific resistance increases. The lowest specific resistance of 6 Ω cm is almost 20 times lower than that of a pure ITO nanoparticle coating. Annealing at 200 °C leads to a further decrease of the specific resistance for all volume fractions of PVP. Specific resistances of 0.5 Ω cm could be achieved for PVP contents of 33–40 vol.%. In addition, the PVP has a strong influence on the electrical conductivity of ITO/PVP coatings under bending which was investigated using a specially constructed device for the application of various bending loads. The ITO/PVP nanocomposite films show a significant lower increase of the sheet resistance under oscillatory bending compared to pure ITO nanoparticle coatings. However, the transmission in the visible range of ITO/PVP nanocomposites decreases with increasing PVP content up to 40 vol.%.