Effect of zinc precursor on Cu₂ZnSnS₄ nanoparticles synthesized by the solvothermal method and its application in dye-sensitized solar cells as the counter electrode

Quaternary elements kesterite nanoparticles in pure kesterite phase were synthesized using solvothermal process with different zinc precursors. Secondary phase formations were observed if zinc acetate or zinc nitrate was used as the precursor. Synthesis of the pure kesterite phase was possible only by using of chlorides of copper (I), tin (II) and zinc and thiourea as the precursors, with ethylene glycol as the solvent. The average size of the kesterite nanoparticle was observed ∼3 nm with a band gap of 1.51 eV. EDX was used to confirm the stoichiometric composition of the nanoparticle. These nanoparticles were used as the counter electrodes in dye-sensitized solar cells and a power conversion efficiency of 7.12% under AM 1.5G illumination was obtained. Kesterite nanoparticle layer can therefore, be used as an alternate counter electrode in the dye-sensitized solar cell to replace costly and rare earth platinum counter electrode.