Surfactant effect on the formation of CuInSe₂ nanowires in solution phase synthesis

Solution-phase synthesis of CuInSe₂ nanowires without using metal nanocrystal catalysts has been demonstrated. The morphology of chalcopyrite CuInSe₂ nanoparticles could be varied from spheres to highly anisotropic nanowires by varying the relative amount of strong and weak binding surfactants passivating the surface. For CuInSe₂ nanowires, weakly binding dioctylphosphine oxide (DOPO) was found to be the key surfactant that enables the anisotropic 1-dimensional growth. Detailed analysis of the structure of the nanowires indicates that they grow perpendicular to (112) planes, with twinning around the growth axis by 60° rotation. The nanowires of CuInSe₂ synthesized in this study exhibit saw-tooth surface morphology resembling a stack of truncated tetrahedra which show a continuous growth mechanism.