Sub-10 nm monodisperse PbS cubes by post-synthesis shape engineering

Sub-10 nm monodisperse PbS cubes are synthesized by reacting quasi-spherical PbS nanocrystals with (NH4)(2)S. This reaction shapes the quasi-spheres into cubes via preferential growth of the (111) facets. A four-band envelope function calculation of the energy levels accounts well for the measured absorption spectra. Initial studies show that PbS cubes can organize into simple square superlattices with short ligands.