Au-PbS core-shell nanocrystals: plasmonic absorption enhancement and electrical doping via intra-particle charge transfer.

We present a comparative study of optical and electronic properties for PbS nanocrystals and Au-PbS core-shell nanostructures. In Au-PbS nanostructures, we observed two nontrivial synergistic effects: (i) extinction enhancement due to coupling of surface plasmon resonance in the Au core to the excitonic states in the semiconducting PbS shell, and (ii) strong p-type electronic doping of Au-PbS nanocrystal solids that we explained by the intraparticle charge transfer between the PbS shell and the Au core.