Growth of CuInS 2 Nanotubes from Cu 2 S-CuInS 2 Heterostructures as a Potential Photovoltaic Material.

Chemically synthesized nanostructures possess well-defined domains with an interconnected network, which helps the carriers to bypass the other material in the solar cell while moving to their respective electrodes. In this work, CuInS2films constituting CuInS2nanotubes and nanoparticles were fabricated using a hot-injection chemical technique, followed by sulfurization. Structural and microstructural investigations reveal Cu2S nanoparticle formation at an early stage of growth of nanotubes, serving as possible catalyst sites for the subsequent anisotropic growth of the heterostructured hexagons. The crossover takes place over a number of intermediate stages. This sharing of the heterostructure by the hexagonal Cu2S and chalcopyrite CuInS2minimizes the lattice distortion. The Cu2S- CuInS2interface in the heterostructure acts as the nucleation center for CuInS2nanotubes. Optical absorption and Raman spectroscopy studies reveal better optical properties for CuInS2nanoparticles as compared to CuInS2nanotubes. Compared to all other nanostructures, nanowires or nanotubes tend to provide single-crystalline nanograins for direct characterization. These nanoparticles, especially the nanotubes, can be used to form an interconnected network structure of p- and n-type materials in bulk heterojunctions providing the key to improve solar cell efficiencies. [ABSTRACT FROM AUTHOR]