Nanocrystals as precursors for flexible functional films

A general strategy for obtaining tailorable and patternable films of densely packed nanocrystals, was investigated using the as-prepared nanocrystals as precursors. A solution containing PbS nanocrystals and the excess pbCl 2-OLA complex was repeatedly drop-cast onto a glass slide until a thick film was formed. The film composed of densely packed nanocrystals separated by the OLA capping ligands. The film was then exposed to a 5-W air plasma for 48 h, after which it was lifted off the substrate without damage. The morphology and the nanoscopic organization of the films was investigated using TEM and scanning electron microscopy (SEM). The nanocrystals formed ordered superstructures, with cubic symmetry. The peak in the small-angle X-ray scattering (SAXS) curve indicated the presence of a residual order in the packing of the nanocrystals. The surface-to-surface distance between nanocrystals was found between 1 and 3 nm.