Nanocrystal Heterostructures Based on Halide Perovskites and Metal Sulfides

Abstract

We report the synthesis of nanocrystal heterostructures composed of CsPbCl 3 and PbS domains sharing an epitaxial interface. We were able to promote the growth of a PbS domain (in competition with the more commonly observed Pb 4 S 3 Cl 2 one) on top of the CsPbCl 3 domain by employing Mn 2+ ions, the latter most likely acting as scavengers of Cl − ions. Complete suppression of the Pb 4 S 3 Cl 2 domain growth was then achieved by additionally selecting an appropriate sulfur source (bis(trimethylsilyl)sulfide, which also acted as a scavenger of Cl − ions) and reaction temperature. In the heterostructures, emission from the perovskite domain was quenched, while emission from the PbS domain was observed, pointing to a type-I band alignment, as confirmed by calculations. These heterostructures, in turn, could be exploited to prepare second-generation heterostructures through selective ion exchange on the individual domains (halide ion exchange on CsPbCl 3 and cation exchange on PbS). We demonstrate the cases of Cl − → Br − and Pb 2+ → Cu + exchanges, which deliver CsPbBr 3 −PbS and CsPbCl 3 −Cu 2-x S epitaxial heterostructures, respectively.