Electrical conduction mechanism in ZnS nanoparticles

•ZnS nanoparticles have been prepared by coprecipitation route with diameter of 20 nm.•The bandgap energy shows small shift as compared to the bulk value of ZnS.•This is explained by weak quantum confinement effects resulted from the quantization of exciton motion.•The photoluminescence spectrum shows two peaks that are assigned to the recombination of electrons and holes.•And to the transitions of electrons from the sulfur to zinc vacancy states.

ZnS nanoparticles with hexagonal wurtzite crystal structure have been prepared by coprecipitation method at 70 °C and subsequently annealed at 400 °C for 4 h. The average particle size has been found to be ∼20 nm. ZnS nanopowder has been characterized by UV–Vis spectrophotometry. The band gap has been calculated in the range of 3.9 eV. Impedance spectroscopic technique has been used to examine the electrical properties of ZnS nanoparticles pressed to pellet form in the temperature range of 300–400 K. Correlated barrier hopping has been the prevailing conduction mechanism in ZnS. The activation energy calculated from the Arrhenius relation is consistent with bipolaron and single polaron hopping in correlated barrier hopping model.