Exploiting the Lability of Metal Halide Perovskites for Doping Semiconductor Nanocomposites

[Image: see text] Cesium lead halides have intrinsically unstable crystal lattices and easily transform within perovskite and nonperovskite structures. In this work, we explore the conversion of the perovskite CsPbBr(3) into Cs(4)PbBr(6) in the presence of PbS at 450 °C to produce doped nanocrystal-based composites with embedded Cs(4)PbBr(6) nanoprecipitates. We show that PbBr(2) is extracted from CsPbBr(3) and diffuses into the PbS lattice with a consequent increase in the concentration of free charge carriers. This new doping strategy enables the adjustment of the density of charge carriers between 10(19) and 10(20) cm(–3), and it may serve as a general strategy for doping other nanocrystal-based semiconductors.