Post-synthetic modification of semiconductor nanoparticles can generate lanthanide luminophores and modulate the electronic properties of preformed nanoparticles

Abstract

Post-synthetic modification of inorganic nanoparticles (NPs) provides a unique lesser synthetically demanding opportunity to access nanomaterials those are oftentimes not directly realizable by conventional synthetic routes. Trivalent lanthanide (Ln3+) incorporated (doped) semiconductor NPs can benefit from individual properties of the NPs and Ln3+ moieties. This work summarizes key outcomes from experiments when (a) ZnS /CdS /CdSe NPs are post-synthetically treated with Ln3+ to generate ZnS/Ln or CdSe/Ln [Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb] and CdS/Ln [Eu, Tb] NPs, (b) synthetically Tb3+ doped Zn(Tb)S NPs are post-synthetically modified with varying concentration of heavy metals like Pb2+/Cd2+ to generate Zn(Tb)S/M [M = Pb, Cd] NPs, and (c) the pH of Zn(Tb)S NPs aqueous dispersion is varied post-synthetically. Key observations from these experiments include (a) incorporation of Ln in all the post-synthetically prepared CA/Ln NPs, with presence of host sensitized dopant emission in select cases that can be rationalized by a charge trapping mediated dopant emission sensitization processes, (b) existence of rich photophysics in the sub-stoichiometric reactant concentration ratio, and (c) identifying the alteration of surface capping ligand structure as an important variable to control the Ln3+ emission. In summary, these experimental observations provide an easy control of reaction conditions either to generate Ln3+ inorganic NP luminophores or to control their electronic properties by modulating either the NP’s core or surface properties, and are of potential usefulness in various luminescence based applications.