Ligand Footprints on CsPbBr3 Nanocrystal Surfaces Probed by Colloidal 133Cs NMR Spectroscopy

Lidiia Dubenska^a^,^b, Sebastian Sabisch^a^,^b, Ole Dressler^a^,^b, Oleksandr Kolomiiets^a^,^b, Willem Verheijen^a^,^b, Maksym Kovalenko^a^,^b

^aETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 1-5, Zürich CH-8093, Switzerland

^bEmpa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf CH-8600, Switzerland

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

D1 Probing ligands on nanocrystals

Palma, Spain, 2026 October 26th - 30th

Organizers: Philippe Green, Ona Segura Lecina and Francisco Yarur Villanueva

Oral, Lidiia Dubenska, presentation 062
Publication date: 22nd July 2026

Lead halide perovskite quantum dots (LHP QDs) stand out due to their compositionally tunable bandgaps, bright and narrow emission, and exceptional tolerance to defects. Their long optical coherence times combined with short radiative lifetimes at cryogenic temperatures make them particularly attractive as quantum light sources. However, to date, atomically resolved structures of LHP QDs remain elusive, particularly at complex heterointerfaces, such as those between the inorganic core and organic ligands. Surfaces strongly influence the stability, optical performance, and reactivity of QDs, making atomically precise insights essential for their rational improvement. To tackle this pressing need, we utilize colloidal ¹³³Cs nuclear magnetic resonance (NMR) spectroscopy, a powerful and non-invasive analytical tool that provides rich, element and site-specific information. To understand the factors governing the ¹³³Cs chemical shift, we combined solid-state NMR measurements of bulk CsPb(Br_xCl_1-x)₃ samples with DFT calculations on representative model systems. We show that the ¹³³Cs chemical shift is the result of the complex interplay between material structure and composition. Leveraging this understanding, we explore surface-ligand interactions unveiling local chemical environments and structural distortions. We present ¹³³Cs NMR spectra of CsPbBr₃ QDs capped with various cationic and zwitterionic ligands. Using the ¹³³Cs chemical shift as a structural descriptor, we assessed the impact of each ligand on the QD surface and identified structural motifs that induce the least surface strain at room temperature. Variable temperature (VT) ¹³³Cs solid-state NMR measurements down to 110 K revealed contraction of the QD core while the surface-associated chemical shift remained unchanged, demonstrating that even the most favourable ligand imposes strain across the QD at low temperature. Considering the operational conditions and associated temperatures needed for coherent quantum light sources these findings provide a basis for rational and application specific ligand design. Moreover, such understanding is crucial for developing reliable computational models that capture structure-property relationships, enabling the forward engineering of QDs with tailored functionalities.

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