Spontaneous formation of wurzite-CdS/zinc blende-CdTe heterodimers through a partial anion exchange reaction.

Ion exchange of ionic semiconductor nanoparticles (NPs) is a facile method for the synthesis of type-II semiconductor heterostructured NPs with staggered alignment of band edges for photoelectric applications. Through consideration of the crystallographic orientation and strain at the heterointerface, well-designed heterostructures can be constructed through ion exchange reactions. Here we report the selective synthesis of anisotropically phase-segregated cadmium sulfide (CdS)/ cadmium telluride (CdTe) heterodimers via a novel anion exchange reaction of CdS NPs with an organic telluride precursor. The wurtzite-CdS/zinc blende-CdTe heterodimers in this study resulted from spontaneous phase segregation induced by the differences in the crystal structures of the two phases, accompanying a centrosymmetry breaking of the spherical CdS NPs. The CdS/CdTe heterodimers exhibited photoinduced spatial charge separation because of their staggered band-edge alignment.