Halide perovskites as disposable epitaxial templates for the phase-selective synthesis of lead sulfochloride nanocrystals

Colloidal chemistry grants access to a wealth of materials through simple and mild reactions. However, even few elements can combine in a variety of stoichiometries and structures, potentially resulting in impurities or even wrong products. Similar issues have been long addressed in organic chemistry by using reaction-directing groups, that are added to a substrate to promote a specific product and are later removed. Inspired by such approach, we demonstrate the use of CsPbCl(3) perovskite nanocrystals to drive the phase-selective synthesis of two yet unexplored lead sulfochlorides: Pb(3)S(2)Cl(2) and Pb(4)S(3)Cl(2). When homogeneously nucleated in solution, lead sulfochlorides form Pb(3)S(2)Cl(2) nanocrystals. Conversely, the presence of CsPbCl(3) triggers the formation of Pb(4)S(3)Cl(2)/CsPbCl(3) epitaxial heterostructures. The phase selectivity is guaranteed by the continuity of the cationic subnetwork across the interface, a condition not met in a hypothetical Pb(3)S(2)Cl(2)/CsPbCl(3) heterostructure. The perovskite domain is then etched, delivering phase-pure Pb(4)S(3)Cl(2) nanocrystals that could not be synthesized directly.