Title

Surface Termination of CsPbBr3 Perovskite Quantum Dots Determined by Solid-State NMR Spectroscopy

Publication Date

3-2-2020

Department

Ames Laboratory; Chemistry

Campus Units

Ames Laboratory, Chemistry

OSTI ID+

1728699

Report Number

IS-J 10193

DOI

10.1021/jacs.9b13396

Journal Title

Journal of the American Chemical Society

Volume Number

142

Issue Number

13

First Page

6117

Last Page

6127

Abstract

Cesium lead halide perovskite quantum dots (QDs) have gained significant attention as next-generation optoelectronic materials; however, their properties are highly dependent on their surface chemistry. The surfaces of cuboidal CsPbBr3 QDs have been intensively studied by both theoretical and experimental techniques, but fundamental questions still remain about the atomic termination of the QDs. The binding sites and modes of ligands at the surface remain unproven. Herein, we demonstrate that solid-state NMR spectroscopy allows the unambiguous assignments of organic surface ligands via 1H, 13C, and 31P NMR. Surface-selective 133Cs solid-state NMR spectra show the presence of an additional 133Cs NMR signal with a unique chemical shift that is attributed to Cs atoms terminating the surface of the particle and which are likely coordinated by carboxylate ligands. Dipolar dephasing curves that report on the distance between the surface ammonium ligands and Cs and Pb were recorded using double resonance 1H{133Cs} and 1H{207Pb} RESPDOR experiments. Model QD surface slabs with different possible surface terminations were generated from the CsPbBr3 crystal structure and theoretical RESPDOR dipolar dephasing curves considering all possible 1H-133Cs/207Pb spin pairs were then calculated. Comparison of the calculated and experimental RESPDOR curves indicates the particles are CsBr terminated (not PbBr2 terminated), with alkylammonium ligands situated within surface Cs vacancies, consistent with the surface-selective 133Cs NMR experiments. These results highlight the utility of high-resolution solid-state NMR spectroscopy for studying ligand binding and the surface structure of nanomaterials.

DOE Contract Number(s)

FG02-11ER46826; SC0006812

Language

en

Department of Energy Subject Categories

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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