Structural and optical characterizations of multi-layered and multi-stacked PbSe quantum dots

A multi-layered nanocomposite thin film was fabricated to increase the density of PbSe quantum dots. It consisted of low-loss polymer layers and multi-stacked PbSe quantum dot layers in series. The solutions of a UV-curable low-loss polymer and PbSe quantum dots were spin-coated layer-by-layer. An arrayed and multi-stacked PbSe quantum dot layer was self-assembled by spin-coating and solvent evaporation. The multi-stacked layers of PbSe quantum dots have a face-centred cubic structure with an average {111} plane distance of ~6.1?nm, determined by small-angle x-ray scattering. The average diameter of PbSe quantum dots is ~5?nm and the average interparticle spacing distance is ~2.5?nm, characterized by transmission electron microscopy. The density of PbSe quantum dots in the single-arrayed layer is ~1.8 ? 1012?cm?2 and the density in the three-layered thin film of multi-stacked PbSe QDs is >1.6 ? 1013?cm?2. The peak intensities of absorption and photoluminescence were increased with increasing number of PbSe quantum dot layers. The time of luminescence decay to e?1 is 138?ns at room temperature. We investigated the structures of multi-layered and multi-stacked PbSe quantum dot thin films as well as their optical properties, and then suggested their photonic applications.