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 similar to 60 degrees 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.