Reduced band gap and diffusion controlled spherical n-type ZnS nanoparticles for absorption of UV-Vis region of solar spectrum

Spherical n-type ZnS nanoparticles have been synthesised by co-precipitation method for absorption of UV-Vis region of solar spectrum without adding any impurity. Rietveld refinement of XRD data confirms that it has Zinc Blende crystal structure with (space group-216). Electrochemical studies have been performed for the synthesised ZnS nanoparticles because the charge that flows through device depends on the amount of oxidation and reduction process: During Cyclic Voltammetry analysis it was observed that electrochemical reaction between electrodes and electrolyte is diffusion-controlled. The diffusion-controlled charge storage mechanism has also been validated by charge transfer resistance (R-ct) and Warburg impedance (Z(w)), obtained after Electrochemical Impedance Spectroscopy (EIS) analysis. Using Randles-sevciks equation, the diffusion coefficient at different scan rates have been calculated to know the rate of movement of particles. The synthesised ZnS nanoparticles are found to be of lower bandgap than the bulk counterpart due to surface defect states. De-convolution of PI data has been done to know the presence of various emissions due to different defect states present in the synthesised ZnS nanoparticles.