Photovoltaic performance and impedance spectroscopy of ZnS-Cu-Go nanocomposites

In this work, novel, non-toxic and cost effective ZnS-Cu-GO nanocomposite is synthesized via wet chemical route to study its photovoltaic properties. Three samples including ZnS,ZnS-Cu and ZnS-Cu-GO were prepared and deposited as sensitizers on ZnO coated FTO substrates to assemble PV devices.The samples were characterized using UV-Vis NIR spectroscopy, Atomic force microscopy (AFM).Electrochemical impedance spectroscopy (EIS) and AM 1.5 Sun Simulator. It was observed that ZnS-Cu-GO exhibitedsuperiorchargetransport, remarkably high open circuit voltage(0.8 V) and Fill factor (0.806).The current density significantly enhanced and maximum solar cell efficiency was observed for ZnS-Cu-GO based PV device. A pronounced red shift of 360 nm in the absorption spectra was observed in the ZnS-Cu-GO due to fine dispersion of GO sheets.The AFM analysis showed that incorporation of GO and Cu maximized grain density and trench like grain boundaries in ZnS-Cu-GO which facilitated charge transport mechanism.A detailed electrochemical impedance study to probe charge dynamics in the prepared PV devices is presented herein.