Characterization of Cu2ZnSnSe4 (CZTSe) nanoparticles synthesized via solvothermal method for solar cell applications

Stannite Cu2ZnSnSe4 (CZTSe) nanoparticles were synthesized using a simple solvothermal process at low temperatures using ethylenediamine as a solvent. The structures and morphologies of CZTSe nanoparticles were characterized as functions of various zinc salts in the precursors. Nanosized CZTSe particles, formed with zinc chloride as the source of zinc and obtained at 240 °C after 30 min of the aforementioned process, exhibited a single CZTSe phase. Increasing the processing duration to 6 h markedly increased the crystallinity of heat treated powders. All particles that were obtained after 6 h 240 °C from various zinc salts exhibited a single tetragonal phase with particle sizes in the range of 30–60 nm. CZTSe nanoparticles that were obtained from zinc chloride and zinc acetylacetonate had better crystallinity compared to particles obtained from other zinc salts. The structural variation in CZTSe that was synthesized from zinc chloride was observed as a function of Cu/(Zn + Sn) ratio. A Cu poor and Zn rich conditions resulted into a highly crystalline CZTSe phase with relatively smooth and closely packed morphology. The CZTSe nanoparticles, obtained from ZnCl2, were evaluated for potential use in solar cells via preparing precursor ink. The contents of the precursor ink were fixed to Cu/(Zn + Sn) = 0.8 and Zn/Sn = 1.2, and the ink was coated onto Mo substrates via drop casting. The GIXRD patterns of the film showed single CZTSe phase without any binary phases throughout the film. These results demonstrated that the as formed CZTSe nanoparticles are suitable for use as absorber layers in low-cost solar cells.