Multiexciton Lifetimes Reveal Triexciton Emission Pathway in CdSe Nanocrystals.

Multiexcitons in emerging semiconducting nanomaterials play a critical role in potential optoelectronic and quantum computational devices. We describe photon resolved single molecule methods to directly probe the dynamics of biexcitons and triexcitons in colloidal CdSe quantum dots. We confirm that biexcitons emit from a spin-correlated state, consistent with statistical scaling. Contrary to current understanding, we find that triexciton emission is dominated by band-edge 1S _e 1S _3/2 recombination rather than the higher energy 1P _e 1P _3/2 recombination.