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 I I I I I plane distance of similar to 6.1 nm, determined by small-angle x-ray scattering. The average diameter of PbSe quantum dots is similar to 5 nm and the average interparticle spacing distance is similar to 2.5 nm, characterized by transmission electron microscopy. The density of PbSe quantum dots in the single-arrayed layer is similar to 1.8 x 10(12) cm(-2) and the density in the three-layered thin film of multi-stacked PbSe QDs is > 1.6 x 10(13) 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.