Near-infrared-emitting CIZSe/CIZS/ZnS colloidal heteronanonail structures.

Multicomponent quantum nanostructures have attracted significant attention due to their potential applications in photovoltaics, optoelectronics and bioimaging. However, the preparation of anisotropic quaternary nanoheterostructures such as Cu-In-Zn-S(Se) (CIZS and CIZSe) is still very poorly explored and understood. Here, we report the synthesis and studies of NIR emissive CIZSe/CIZS/ZnS core/shell/shell nanoheterostructures with a unique hetero-nanonail (HNN) morphology. In our approach, wurtzite (WZ) CIZSe/CIZS core/shell QDs have been prepared by depositing a CIZS shell onto a previously synthesized chalcopyrite CIZSe QD core using a seeded growth technique. Following careful control of the ZnS shell growth resulted in the formation of the distinct nail-like CIZSe/CIZS/ZnS nanoheterostructure, where the CIZSe/CIZS core/shell QD is located near the "head" of the nail. The emission in the NIR region of the CIZSe/CIZS/ZnS nanocrystals is assigned to the CIZSe/CIZS core/shell quantum nanostructure. The CIZSe/CIZS/ZnS HNNs are particularly interesting due to a range of potential applications including bioimaging, biosensing, energy harvesting and NIR photodetectors. Finally, we also report the successful controlled growth of gold nanoparticles on the surface of the CIZSe/CIZS/ZnS nanonail-like heterostructure and the investigation of the resulting multimodal nanocomposites.