Synthesis and Photoelectrochemical Properties of (Cu2Sn)xZn3(1-x)S3 Nanocrystal Films

This work provides new routes for developing efficient photoelectrodes for photoelectrochemical (PEC) water splitting using a low-cost electrophoretic film preparation method. A series of (Cu2Sn)(x)Zn3(l-x)S3 (0 <= x <= 0.75) quaternary nanocrystals (NCs) with tunable optical band gaps are synthesized. Morphologies including particles, rods, and wires are obtained by tuning the composition of the NCs. (Cu2Sn)(0.75)Zn0.75S3 (Cu2ZnSnS4) has a pure kesterite structure, but an increase in the Zn content results in a kesterite-wurtzite polytypism. (Cu2Sn)(x)Zn3(1-x)S3 films are fabricated from their colloidal solutions via electrophoretic deposition, and the PEC properties of these films with p-type character have been examined under water-splitting conditions. It is shown that the photocurrent varies as a function of film thickness as well as chemical composition. The produced (Cu2Sn)(0.45)Zn1.65S3 (x = 0.45) film has the highest photocurrent, and the incident photon to current conversion efficiency is improved compared with previously reported results of Cu2ZnSnS4 photocathodes.