Luminescent semiconducting quantum dots (QDs) are central to emerging technologies that range from tissue imaging to solid-state lighting. However, existing samples are heterogeneous, which has prevented atomic-resolution determination of their structures and obscured the relationship between their atomic and electronic structures.

In this work, we synthesized, isolated and structural characterized  three cadmium selenide QDs with uniform compositions. Using a combination of single-crystal X-ray diffraction and atomic pair distribution function analysis, we determine the structures of their inorganic cores, revealing a series of pyramidal nanostuctures with cadmium terminated {111} facets. Theoretical and experimental studies on these materials will open the door to a deeper fundamental understanding of structure–property relationships in quantum-confined semiconductors.

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A. N. Beecher, X. Yang, J. H. Palmer, A. L. LaGrassa, P. Juhás, S. J. L. Billinge and J. S. Owen, Atomic Structures and Gram Scale Synthesis of Three Tetrahedral Quantum Dots, J. Am. Chem. Soc.136, 10645-10653 (2014)