Fabrication and Photoelectrochemical Behavior of n-Type Cu ₂ZnSnSe₄ Thin-Film Electrodes Prepared via Non-Vacuum Nanoinks Process

Colloidal Cu2ZnSnSe4 (CZTSe) nanoparticles with sizes of 20-25 nm that contain no highly toxic elements were successfully synthesized through facile reactions of elemental sources in polyetheramine solution. After reacting elemental Cu, Zn, Sn, and Se powders in an autoclave with polyetheramine as the solvent, spherical CZTSe nanocrystals (NCs) with diameters of 20-30 nm were obtained. In the synthesis, the polyetheramine solvent provides a high reactivity because of its double N-chelation. Optical measurements revealed nanocrystals with a direct bandgap of 1.57 eV. The synthesis of CZTSe NCs can be applied to photodevices using a relatively simple, low-cost, and convenient coordinating solvent route. Nanoparticles were successfully accumulated on quartz glass substrates via spin coating. Upon controlling the Zn-to-Sn ratio, the resulting CZTSe particle films exhibited a photoresponse similar to that of n-type semiconductor photoelectrodes in an aqueous solution containing NaCl as an electron scavenger. Potentials of the valence band edge and the conduction band edge were determined from the onset potential of the cathodic photocurrent to be -0.8 and 0.8 V vs. Ag/AgCl, respectively.