Near-Edge Ligand Stripping and Robust Radiative Exciton Recombination in CdSe/CdS Core/Crown Nanoplatelets

Jari Leemans, Shalini Singh, Chen Li, Stephanie Ten Brinck, Sara Bals, Ivan Infante, Iwan Moreels, Zeger Hens*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We address the relation between surface chemistry and optoelectronic properties in semiconductor nanocrystals using core/crown CdSe/CdS nanoplatelets passivated by cadmium oleate (Cd(Ol)2) as model systems. We show that addition of butylamine to a nanoplatelet (NPL) dispersion maximally displaces ∼40% of the original Cd(Ol)2 capping. On the basis of density functional theory simulations, we argue that this behavior reflects the preferential displacement of Cd(Ol)2 from (near)-edge surface sites. Opposite from CdSe core NPLs, core/crown NPL dispersions can retain 45% of their initial photoluminescence efficiency after ligand displacement, while radiative exciton recombination keeps dominating the luminescent decay. Using electron microscopy observations, we assign this robust photoluminescence to NPLs with a complete CdS crown, which prevents charge carrier trapping in the near-edge surface sites created by ligand displacement. We conclude that Z-type ligands such as cadmium carboxylates can provide full electronic passivation of (100) facets yet are prone to displacement from (near)-edge surface sites.

Original languageEnglish
Pages (from-to)3339-3344
Number of pages6
JournalThe journal of physical chemistry letters
Volume11
Issue number9
Early online date10 Apr 2020
DOIs
Publication statusPublished - 7 May 2020

Funding

Z.H. and S.B. acknowledge support by SIM-Flanders (SBO-QDOCCO). Z.H. acknowledges support by FWO-Vlaanderen (research project 17006602). Z.H. and I.M. acknowledge support by Ghent University (GOA n° 01G01019). J.L. acknowledges FWO-vlaanderen for a fellowship (SB Ph.D. fellow at FWO). S.S. acknowledges FWO postdoctoral funding (FWO17/PDO/184). This project has further received funding from the European Research Counsil under the European Union’s Horizon 2020 research and innovation programme (ERC Consolidator Grant 815128 REALNANO and Starting Grant 714876 PHOCONA). The computational work was carried out on the Dutch national e-infrastructure with the support of the SURF Cooperative.

FundersFunder number
FWO-Vlaanderen17006602
SBO-QDOCCO
SIM-Flanders
Horizon 2020 Framework Programme815128, 714876
European Resuscitation Council714876 PHOCONA
European Research Council
Universiteit GentFWO17/PDO/184, 01G01019

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