Synthesis of dot in rod semiconductor heterostructures for the engineering of nanocrystals optical properties

This paper focuses on a preliminary study based on a two-steps approach to produce complex core/multiple shell architectures, such as "dots-in-rods"(DRs), to be exploited as color down-conversion filters for display manufacturing. Core/shell CdSe/CdS DRs are prepared by using a conventional fast hot injection reaction method to grow CdS layers onto CdSe QDs cores. Then, the CdSe/CdS DRs are engineered by growing an additional CdS shell coated by oleate (OA) molecules, thus producing CdSe/CdS@CdS/OA DRs. This further hybrid shell is synthesized by means of a seeded-growth approach, consisting of the controlled injection of TOP-S and cadmium oleate (Cd(OA)2) as sulfur and cadmium precursors, respectively. As assessed by transmission electron microscopy (TEM) and UV-Vis absorption and photoluminescence (PL) spectroscopies analyses, the feasibility to control the amount of precursors allows to modulate the thickness of the further hybrid shells and therefore the morphological and optical properties of the final heterostructures. The introduction of further shells grafted by specific organic ligand improves the solubility in polymeric matrices. This condition is crucial to produce hybrid nanocomposite films that can be integrated in display manufacturing applications. Moreover, the capability of the final CdSe/CdS@CdS/OA nanostructures to convert blue light in red wavelengths with a remarkable photoluminescence quantum yields (PLQY) makes the produced materials the ideal candidates for a variety of optoelectronic applications, particularly for the fabrication of color down-conversion filters.