Development and electrical characterization of screen-printed electrode based on ZnO nanoparticles

Thick-film electrode based on ZnO nanoparticles was prepared by screen printing coupled with sol-gel technique on interdigitated device. The sample was subjected to structural, morphological and electrical characterization by using X-ray diffraction, scanning and transmission electron microscopies (SEM and TEM) and impedance spectroscopy. The unit cells are of hexagonal wurtzite phase. The obtained nanoparticles are in prismatic shape with a size of about 30 nm agglomerated in microspheres. After deposition, the electrical study depicts that the conductivity fits well the Jonscher's law. Carriers move in agreement with correlated barrier hopping model over dispersive region. The hopping carriers are generated mainly by vacant sites and interstitial defects. Nyquist diagram indicates that grains and grain boundaries dominate at low temperatures, while only grain boundaries dominate at high temperatures. The obtained results are promising to explain the origin of conductivity and the sites responsible for the activity of unintentionally doped ZnO particularly for gas sensing and biological applications.