Reaction Precursor-Mediated Formation of Stable Supercrystals in Colloidal Nanocrystal Synthesis: PbTe Case
Seungho Lee a, Daniel Balazs a, Sharona Horta a, Aiswarya Rayaroth Puthiyaveettil a, Maria Ibáñez a
a Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS Spring 2025 Conference (MATSUSSpring25)
Advances in Nanocrystals: Fundamental approaches and technological perspectives - #NCAdv
Sevilla, Spain, 2025 March 3rd - 7th
Organizers: Carmelita Rodà and Matteo Zaffalon
Oral, Seungho Lee, presentation 173
DOI: https://doi.org/10.29363/nanoge.matsusspring.2025.173
Publication date: 16th December 2024

Supercrystals represent three-dimensional orderings of colloidal nanocrystals (NCs), showcasing collective properties in photonics, phononics, and electronics applications.1,2 Recent studies have shown that such assemblies are directly produced during nanocrystal reactions.3–6 However, a fundamental understanding of in situ formed supercrystals that withstand typical NC purification processes remains underexplored, which is important for further use. Herein, we report the reaction precursor-mediated formation of stable PbTe supercrystals. Rationalizing the formation of these assemblies through small-angle x-ray scattering (SAXS) measurements, we unveil their formation mechanism. Our findings reveal that the supercrystal formation occurs in the presence of an excess of lead oleates in the crude solution. It should be noted that the formed supercrystals can be stabilized under specific conditions determined by the lead oleate cluster concentration, content of trioctylphosphine telluride (TOP-Te), NC size and the need of an annealing step at mild conditions. Furthermore, this approach allows for the continuous growth of a secondary phase within the supercrystal; for example in the case of PbTe supercrystals, a PbS shell can be grown on each PbTe NC constituent, resulting in core-shell PbTe-PbS supercrystals. Our work elucidates that reaction precursors play an important role in in situ SC formation and stabilization, implying the possibility of applying this knowledge to other NC reactions.

ISTA and the Werner Siemens Foundation financially supported this work. The Scientific Service Units (SSU) of ISTA supported this research through resources provided by the Electron Microscopy Facility (EMF), NMR Facility and the Lab Support Facility (LSF).

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