Honeycomb-structured copper indium sulfide thin films obtained via a nanosphere colloidal lithography method

Abstract

The large surface-to-volume ratio and the huge surface area of an ordered nanostructure is essential for improving the performance of many metal sulfide-based technologies within energy conversion and storage, but also catalysis and sensing. Although, several routes toward the formation of nanostructured metal sulfide thin films have been already developed, their fabrication is still challenging. Herein, we present a novel method for the preparation of honeycomb-structured CuInS₂ thin films via a nanosphere colloidal lithography technique using monodisperse polystyrene nanosphere layers, formed by a self-assembly approach at the air/liquid interface, as template. The size of the spheres can be reduced by an O₂ plasma etching process, thereby enlarging the free space between the spheres. Infiltration of the template with metal xanthates followed by their thermal conversion to CuInS₂ and the thermal removal of the polymeric template leads to ordered honeycomb-structured films. In an alternative route, the template is infiltrated with a tailored CuInS₂ nanoparticle ink before the template is removed by dissolution.