Effect of Dopants on the Performance of ZnSe Nanoparticles as Photocathode for Dye Sensitized Solar Cell

Zinc selenide (ZnSe), copper, nickel, and cobalt doped ZnSe (Cu, Ni, Co-ZnSe) nanoparticles were effectively synthesized through solvothermal method. The as-synthesized ZnSe nanoparticles were described to their optical, structural, elemental composition, morphological properties and electrochemical studies. X-ray diffraction pattern supports hexagonal, wurtzite structure and the crystallite sizes were justified as 13.7, 13.1, 10.6 and 7.9 nm for ZnSe, Cu, Ni and Co-ZnSe nanoparticles respectively, which are further confirmed by TEM analysis. Band-gap energy was computed as 2.5, 2.7, 3.2 and 3.5 eV for ZnSe, Cu, Ni, Co-ZnSe nanoparticles. Scanning electron microscopic images showed the formation of rod shaped nanoparticles, and the effective doping was further confirmed by EDX spectral analysis. The kinetics of electron transport properties were studied by electrochemical analysis and it was found that Co-ZnSe has more electrocatalytic activity compared to Cu, Ni- ZnSe nanoparticles. DSSCs were fabricated with ruthenium dye immobilized semiconductor photo anode (TiO2), redox electrolyte (I-/I3 -), ZnSe, Cu, Ni and Co-ZnSe nanoparticles as counter electrodes (CE). The maximum power conversion efficiency of solar cells was found to be 1.20%, 1.99%, 2.51% and 3.21% for ZnSe, Cu, Ni and Co- ZnSe nanoparticles, and it was found that the dopant with more number of unpaired electron influences the solar cell effectively.