Template-directed fabrication of vertically aligned Cu₂ZnSnS₄nanorod arrays for photoelectrochemical applications via a non-toxic solution process

Cu₂ZnSnS₄(CZTS), which is non-toxic and abundantly available, is a promising material for fabricating inexpensive large-scale photoelectrochemical (PEC) devices. With the current rapid developments in nanotechnology, one-dimensional (1D) semiconductor nanostructures have been widely investigated because of their short transport distance for photogenerated carriers, large specific surface areas, and efficient optical absorption, all of which are advantageous features. However, PEC devices based on vertical arrays of 1D CZTS nanostructures have not yet been realized. In this study, we report the fabrication of vertically aligned CZTS nanorod arrays using an anodic aluminum oxide template-assisted solution process. The nanorods exhibit a relatively pure phase with a CZTS kesterite structure and cathodic photocurrent response. The surfaces of the CZTS nanorod arrays were decorated with either ZnS or CdS via chemical bath deposition to increase the photocurrent with a positive flat band potential. By analyzing the photocurrent and flat band potential, we gained an insight into the effect of band alignment between the p-type CZTS and the n-type material.