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We report room-temperature ordered multiphoton emission from multiexciton states of single CdSe(CdZnS) core(-shell) colloidal nanocrystals (NCs) that are synthesized by wet chemical methods. Spectrally and temporally resolved measurements of biexciton and triexciton emission from single NCs are also presented. A simple four level system models the results accurately and provides estimates for biexciton and triexciton radiative lifetimes and quantum yields.

We investigate the effect of the electronic energy level positioning, conductivity, and morphology of metal oxide charge transport layers on the performance of light emitting devices (LEDs) that consist of a colloidally synthesized quantum dot (QD) luminescent film embedded between electron and hole injecting ceramic layers. We demonstrate that understanding of these material properties and their effect on charging processes in QDs enables the systematic design of higher efficiency QD-LEDs and excitation of QDs with different emission colors using the same device structure.

We demonstrate a hybrid inorganic/organic light-emitting device composed of a CdSe/ZnS core/shell semiconductor quantum-dot emissive layer sandwiched between p-type NiO and tris-(8-hydroxyquinoline) aluminum (Alq3), as hole and electron transporting layers, respectively. A maximum external electroluminescence quantum efficiency of 0.18% is achieved by tuning the resistivity of the NiO layer to balance the electron and hole densities at quantum-dot sites.

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