Nanocrystals of Lead Chalcohalides: A Series of Kinetically Trapped Metastable Nanostructures

Stefano Toso, Quinten A. Akkerman, Beatriz Martín-García, Mirko Prato, Juliette Zito, Ivan Infante*, Zhiya Dang, Anna Moliterni*, Cinzia Giannini, Eva Bladt, Ivan Lobato, Julien Ramade, Sara Bals*, Joka Buha, Davide Spirito, Enrico Mugnaioli, Mauro Gemmi*, Liberato Manna*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


We report the colloidal synthesis of a series of surfactant-stabilized lead chalcohalide nanocrystals. Our work is mainly focused on Pb4S3Br2, a chalcohalide phase unknown to date that does not belong to the ambient-pressure PbS-PbBr2 phase diagram. The Pb4S3Br2 nanocrystals herein feature a remarkably narrow size distribution (with a size dispersion as low as 5%), a good size tunability (from 7 to ∼30 nm), an indirect bandgap, photoconductivity (responsivity = 4 ± 1 mA/W), and stability for months in air. A crystal structure is proposed for this new material by combining the information from 3D electron diffraction and electron tomography of a single nanocrystal, X-ray powder diffraction, and density functional theory calculations. Such a structure is closely related to that of the recently discovered high-pressure chalcohalide Pb4S3I2 phase, and indeed we were able to extend our synthesis scheme to Pb4S3I2 colloidal nanocrystals, whose structure matches the one that has been published for the bulk. Finally, we could also prepare nanocrystals of Pb3S2Cl2, which proved to be a structural analogue of the recently reported bulk Pb3Se2Br2 phase. It is remarkable that one high-pressure structure (for Pb4S3I2) and two metastable structures that had not yet been reported (for Pb4S3Br2 and Pb3S2Cl2) can be prepared on the nanoscale by wet-chemical approaches. This highlights the important role of colloidal chemistry in the discovery of new materials and motivates further exploration into metal chalcohalide nanocrystals.

Original languageEnglish
Pages (from-to)10198-10211
Number of pages14
JournalJournal of the American Chemical Society
Issue number22
Early online date6 May 2020
Publication statusPublished - 3 Jun 2020


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