In the present communication, the self-assembly of nanocrystalline PbS at the liquid–liquid interface is reported. The PbS nanocrystals were, subsequently, transformed in the form of thin films by dip coating. The resultant Q-PbS films were characterized by SEM–EDAX, TEM–SAED, XRD, XPS and UV–vis Spectroscopy. Pyramidal features at the nanometer scale, preferred orientation along (220) and (400) planes of cubic structure and a sharp excitonic peak at 656nm are the salient aspects of this work. The band-gap of the order of 1.8eV (associated with the excitonic feature) is ideally suited for solar photovoltaic applications.