Strong, Weak, Static, and Dynamic Ligand Binding to Lead Halide Perovskite Nanocrystals

Dmitry Dirin^a^,^b, Yuliia Berezovska^a^,^b, Yesim Sahin^a^,^b, Sebastian Sabisch^a^,^b, Willi Amberg^a, Henry Lindner^a, Erich Staudinger^a, Viktoriia Morad^a^,^b, Leon Feld^a^,^b, Yuxuan Li^a, Caterina Bernasconi^a^,^b, Erick Carreira^a, Maryna Bodnarchuk^a^,^b, Maksym Kovalenko^a^,^b

^aDepartment of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland

^bLaboratory for Thin Films and Photovoltaics, Empa—Swiss Federal Laboratories for Materials Science and Technology, Switzerland

Proceedings of Emerging Light Emitting Materials 2025 (EMLEM25)

La Canea, Greece, 2025 October 8th - 10th

Organizers: Maksym Kovalenko and Grigorios Itskos

Oral, Dmitry Dirin, presentation 079
Publication date: 17th July 2025

Lead halide perovskites (LHPs) have disrupted the field of visible-range emitting colloidal semiconductor nanocrystals (NCs) owing to their exceptional emissivity as classical and quantum light sources. Their appeal is countered by stability challenges arising from lattice softness and labile surface ligand bonding. Recent ligand design efforts have improved structural integrity by introducing strongly and statically bound ligands, such as zwitterionic head groups. We envision ligands with diverse head groups and tails to span a spectrum of binding strengths and dynamics at LHP NC surfaces. Binding strength dictates the equilibrium between bound and free ligands, while exchange rates are governed by the activation barriers of adsorption and desorption. This framework defines four binding modalities: weak-dynamic, weak-static, strong-static, and strong-dynamic.

Using diffusion-ordered NMR spectroscopy (DOSY NMR), we mapped widely used ligands into these regimes and found that common ligands populate the first three. The community’s emphasis on strong-static ligands reflects the need for stability in light-emitting applications. Yet, the strong-dynamic regime remained unexplored, despite its potential to combine surface accessibility with structural integrity - an essential balance for photocatalysis.

To address this gap, we introduced guanidinium ligands, which merge the compactness of primary ammoniums with the deprotonation resistance of quaternary ammoniums. These ligands deliver high photoluminescence quantum yields (up to 95%) and enable rigorous purification and processing in polar environments. Their strong yet dynamic binding enhances photocatalytic C-C coupling, while complementary C-H bromination studies underscore the role of dynamic surfaces, achieving turnover numbers above 9,000,000 per NC at loadings below 100 ppb.

These insights establish ligand binding dynamicity as the second, besides binding strength, key design principle for tailoring perovskite NCs.

References:

[1] Amberg, W.; Lindner, H.; Sahin, Y; Staudinger, E.; Morad, V.; Sabisch, S.; Feld, L.; Li, Y; Dirin, D.; Kovalenko, M.; Carreira, E. Ligand Influence on the Performance of Cesium Lead Bromide Perovskite Quantum Dots in Photocatalytic C(sp3)–H Bromination Reactions. J. Am. Chem. Soc. 2025, 147, 8548−8558.

[2] Berezovska, Y.; Sabisch, S.; Bernasconi, C.; Sahin, Y.; Bertolotti, F.; Guagliardi, A.; Bodnarchuk, M.; Dirin, D.; Kovalenko M. Tightly yet Dynamically Bound Aliphatic Guanidinium Ligands for Lead Halide Perovskite Nanocrystals. J. Am. Chem. Soc., accepted

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