Unveiling the local elemental arrangements across the interfaces inside CdSe/Cd1-xZnxS core-shell and CdSe/CdS/ Cd1-xZnxS core-crown-shell quantum wells

TL;DR

This study systematically analyzes elemental distributions and interatomic bonds at interfaces in CdSe-based core-shell and core-crown-shell quantum wells, revealing how elemental arrangements evolve with core size and aging, impacting stability.

Contribution

First experimental assessment of elemental arrangements and interatomic bonds at interfaces in CdSe-based core-shell nanostructures, highlighting structural heterogeneity and stability over time.

Findings

Cd-Se bonds dominate at smaller cores; more abundant at larger cores.

Elemental distributions change with aging, indicating partial degradation.

Provides insights into growth paths and stability of core-shell nanostructures.

Abstract

We report on a systematic study of the Cd, Zn, Se, and S elemental distributions across the interfaces in CdSe/Cd1-xZnxS core-shell and CdSe/CdS/Cd1-xZnxS core-crown-shell quantum wells with the CdSe core thickness ranging from 3.5 to 5.5 ML. By processing the XAS data, we observe that the Cd-Se bonds dominate at the CdSe/Cd1-xZnxS core-shell interface of structures with the 3.5 ML cores, while the Cd-Se bonds were more abundant in the cases of the 4.5 and 5.5 ML cores. The complementary information about prevailing bonds were extracted for other constituting elements, thus, describing the distribution of the elements at the core-shell interface of CdSe-based NPLs. The naked CdSe cores are covered with an organic shell via bridging oxygen atoms. Also, we address the issue of stability of such core-shell systems over the time. We demonstrate that after a half year of aging of the commercial-ready 4.5 ML CdSe/CdxZn1-xS NPLs, the Cd-Se bonds become more evident due to the partial degradation of the Cd-S bonds. This is the first experimental assessment of prevailing interatomic bonds at the core-shell interface in the CdSe-based NPLs of incremental structural heterogeneity, providing factual evidences about the elemental arrangement inside the core-crown-shell NPLs and the growth path of crowns and shells.