Transformative Synthesis of a Single-Sized PbSe Nanocluster via Cation Exchange

Achieving atomic-level control in IV–VI semiconductor nanomaterials remains an important challenge. Here, we report the synthesis of an ultrasmall, single-sized PbSe nanocluster via cation exchange of a Cu26Se13 template cluster with an atomically defined lead­(II) 4-tert-butylbenzoate compound. The resulting PbSe cluster exhibits a sharp and reproducible excitonic absorption peak at 546 nm (linewidth, 61 nm or 0.25 eV) and red emission at 750 nm with a quantum yield of 5–10%. In contrast to the starting icosahedral Se13 lattice, the resulting PbSe cluster adopts a rock salt structure with a cubic close packing of anions, indicating a transformation of the anion lattice during cation exchange. A combined analysis using structural modeling, powder X-ray diffraction, and X-ray photoelectron spectroscopy suggests that the single-sized cluster is likely a Pb38Se13 species. Our method demonstrates the feasibility of cation exchange transformation for synthesizing single-sized IV–VI nanoclusters, offering a new approach toward atomic-level control of these materials.