Structural and optical characterizations of multi-layered and multi-stacked PbSe quantumdots

Abstract

A multi-layered nanocomposite thin film was fabricated to increase the density of PbSequantum dots. It consisted of low-loss polymer layers and multi-stacked PbSe quantum dotlayers in series. The solutions of a UV-curable low-loss polymer and PbSe quantum dotswere spin-coated layer-by-layer. An arrayed and multi-stacked PbSe quantum dot layer wasself-assembled by spin-coating and solvent evaporation. The multi-stacked layers of PbSequantum 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-arrayedlayer 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 withincreasing number of PbSe quantum dot layers. The time of luminescence decay toe−1 is 138 ns at room temperature. We investigated the structures of multi-layered andmulti-stacked PbSe quantum dot thin films as well as their optical properties, and thensuggested their photonic applications.