Examining the Role of Chloride Ligands on Defect Removal in Imperfectly Attached Semiconductor Nanocrystals for 1D and 2D Attachment Cases

TL;DR

This study investigates how chloride ligands influence defect removal during the assembly of semiconductor nanocrystals, revealing their effectiveness in 1D attachments but limited impact in 2D arrays, informing future nanostructure synthesis.

Contribution

It provides new insights into the role of chloride ligands in defect remediation during nanocrystal attachment, highlighting dimensionality-dependent effects.

Findings

Chloride accelerates defect removal in 1D nanocrystal dimers.

No significant effect of chloride on defect removal in 2D nanocrystal arrays.

Differences attributed to fundamental attachment mechanisms between 1D and 2D systems.

Abstract

Semiconducting, core-shell nanocrystals (NCs) are promising building blocks for the construction of higher dimensional artificial nanostructures using oriented attachment. However, the assembly and epitaxial attachment steps critical to this construction introduce disorder and defects which inhibit the observation of desirable emergent electronic phenomena. Consequently, understanding defect formation and remediation in these systems as a function of dimensionality is a crucial step to perfecting their synthesis. In this work, we use in situ high resolution transmission electron microscopy to examine the role of chloride ligands as remediator agents for imperfect attachment interfaces between CdSe/CdS core-shell NCs for both 1D and 2D attachment cases. In the 1D case, we find that the presence of chloride additives in imperfectly attached NC dimers can result in defect removal speeds nearly twice as large as those found in their plain, non-chloride treated counterparts. However, when we increased the dimensionality of the system and examined 2D NC arrays, we found no statistically significant difference in attachment interface quality between the chloride and non-chloride treated samples. We propose that this discongruity arises from fundamental differences between 1D and 2D NC attachment and discuss synthetic guidelines to inform future nanomaterial superlattice design.