Effect of Solvent Chelating on Crystal Growth Mechanism of CZTSe Nanoink in Polyetheramine

This paper reports on the reaction mechanism of Cu₂ZnSnSe₄ (CZTSe) nanoink via a solvent-thermal reflux method using copper (Cu), zinc (Zn), tin (Sn), and selenium (Se) powders as precursors and polyetheramine as a reaction solvent. The formation of CZTSe nanoparticles in polyetheramine began with the formation of binary phase CuSe₂ due to the strong catalysis provided by polyetheramine. This was followed by the formation of binary phase ZnSe crystals. In the final stage, ternary crystals of Cu₂SnSe₃ transformed into well-dispersed nanocrystals of Cu₂ZnSnSe₄, which are derived from the characterization of XRD, Raman, and TEM. The size of the crystals was shown to decrease with reaction time due to the emulsification effect of the polyetheramine epoxy group. Quaternary phase CZTSe first appeared at 20 h, and then the composition of the CZTSe tended to become Cu-poor and Zn-rich over time. The proposed reaction mechanism of CZTSe nanoparticles in polyetheramine presented a distinct phase transformation and suitable time-composition properties, which benefited to further solution-based solar cell application.