Figure 1.

(a) Scheme of the synthesis of PbS/CdS core/shell nanocrystals driven by cationic Cd for Pb exchange starting with pure PbS NCs (red sphere) in the rock salt crystal phase and resulting in core/shell particle with the same diameter, but surrounded by a CdS shell (blue). (b) High resolution TEM image of a single 9 nm sized core/shell NC after 3 h of exchange time, where the dashed circles indicate the PbS core (red) and the CdS shell region (blue). (c) PL spectra of large sized PbS and PbS/CdS NCs with diameters D of around 9 nm, measured after different reaction time steps.