Heavy-metal-free colloidal nanocrystal heterostructures – synthetic chemistry and growth mechanisms
type: CreativeWork
description: Building heterostructures of colloidal nanocrystals by bringing different components into contact can improve existing or impart novel properties, which enables applications as light emitters in already-commercialized and near-future products. However, the majority of the research has been based on compositions with heavy metals (e.g., cadmium or lead) posing toxicity concerns to the consumers. Therefore, a better understanding of the synthetic chemistry and the growth mechanisms for heavy-metal-free nanocrystal heterostructures is critical before their commercialization potential becomes reality. Here, we have developed novel synthetic strategies to achieve the anisotropic growth of colloidal nanocrystals and the introduction of multiple components with tunability of their positions in the heterostructures, as well as to improve the photoluminescence quantum yield (PL QY) of nanocrystals. We first examine how different Cu precursors in the synthesis of colloidal copper sulfide (Cu2-xS) nanocrystals affect the resulting shape and phase. Decreasing aspect ratio in 1D nanorods (eventually transitioning to 2D nanodisks) observed is consistent with the expected effects of decreasing Cu precursor reactivity. Nanorods are predominantly chalcocite at the early stages of growth but a phase transition to djurleite occurs accompanied by a change in tip faceting upon further growth. In contrast, nanodisks appear in the djurleite phase early on and remain so upon continued growth. Secondly, the high copper vacancy density and the high cation mobility in the Cu2-xS nanorods favor cation exchange, and the remaining Cu2-xS after partial cation exchange can serve as the catalyst for the subsequent solution-liquid-solid (SLS)-like growth. The interplay between cation exchange and SLS-like growth leads to tapered rod-rod, body/tail, or barbell-like Cu2-xS/ZnS heterostructures, which can be controlled by the Zn precursor and ligand choice. Finally, using a similar procedure, spontaneo…
abstract: Building heterostructures of colloidal nanocrystals by bringing different components into contact can improve existing or impart novel properties, which enables applications as light emitters in already-commercialized and near-future products. However, the majority of the research has been based on compositions with heavy metals (e.g., cadmium or lead) posing toxicity concerns to the consumers. Therefore, a better understanding of the synthetic chemistry and the growth mechanisms for heavy-metal-free nanocrystal heterostructures is critical before their commercialization potential becomes reality. Here, we have developed novel synthetic strategies to achieve the anisotropic growth of colloidal nanocrystals and the introduction of multiple components with tunability of their positions in the heterostructures, as well as to improve the photoluminescence quantum yield (PL QY) of nanocrystals. We first examine how different Cu precursors in the synthesis of colloidal copper sulfide (Cu2-xS) nanocrystals affect the resulting shape and phase. Decreasing aspect ratio in 1D nanorods (eventually transitioning to 2D nanodisks) observed is consistent with the expected effects of decreasing Cu precursor reactivity. Nanorods are predominantly chalcocite at the early stages of growth but a phase transition to djurleite occurs accompanied by a change in tip faceting upon further growth. In contrast, nanodisks appear in the djurleite phase early on and remain so upon continued growth. Secondly, the high copper vacancy density and the high cation mobility in the Cu2-xS nanorods favor cation exchange, and the remaining Cu2-xS after partial cation exchange can serve as the catalyst for the subsequent solution-liquid-solid (SLS)-like growth. The interplay between cation exchange and SLS-like growth leads to tapered rod-rod, body/tail, or barbell-like Cu2-xS/ZnS heterostructures, which can be controlled by the Zn precursor and ligand choice. Finally, using a similar procedure, spontaneo…
author: Zhai, You
language: en
keywords: Colloidal nanocrystals, Heterostructures, Heavy-metal-free, Synthesis, Growth mechanisms, Precursor chemistry, Cation exchange, Solution-liquid-solid-like growth, Catalytic growth, Shape control, Phase change, 1D nanorods, 2D nanodisks, Djurleite, Chalcocite, Copper sulfides, Zinc sulfide, Copper gallium sulfide, Copper indium sulfide, Spontaneous multiple segment formation, Tailed nanorods, Crystal facet selectivity, Preferential surface adsorption, Steric hindrance, Precursor reactivity, Strain, Doping semiconductor nanocrystals, Ostwald ripening, Dopant loss, Dopant clustering, Size dependence, Surface modification, Surface passivation, Zinc telluride, Zinc selenide shell, Selenium powder, Shell thickness, Photoluminescence quantum yield, Photoluminescence lifetime, Organic ligands, Photoluminescence quenching
date published: 2017-08-10T19:51:58Z
date modified: 2026-07-22T22:24:34Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/97576