Optimizing the structural, morphological and thermoelectric properties of zinc oxide by the modulation of cobalt doping concentration

•Growth of MgSnO nanoparticles by hydrothermal method.•Effect of Sn concentration on thermoelectric properties of MgSnO.•Thermoelectric properties enhanced by Sn concentration.•Enhancement of thermoelectric properties is due to generation of secondary phases.•Confirmation of secondary phases done by XRD and Raman spectroscopy. A study is conducted to determine the effects of cobalt doping concentration on structural, morphological and thermoelectric properties of Zinc Oxide (ZnO). To test this hypothesis, cobalt doped zinc oxide nano-particles are prepared by hydrothermal method by modulating the Cobalt (Co) concentration from 0.1 to 0.5. The X-Ray Diffraction (XRD) and Raman data is suggested that crystallinity of grown samples is found to be decreased by increasing the concentration of Co atoms. The poor crystallinity of the sample having higher concentration of Co atoms is due to the emergence of secondary phases. The value of Seebeck coefficient is also improved with doping as indicated by the high Seebeck value (250 µV/°C) of Zn0.5Co0.5O. This enhancement of Seebeck coefficient is linked with the number of secondary phases. In contrast, electrical conductivity is reduced due to the generation of the impurity level close to the conduction band. In conclusion, at higher doping content, the overall power factor is enhanced with a slow increase in Seebeck coefficient and decrease in electrical conductivity by doping content.