Surface oxidation of CdTe nanocrystals—A high resolution core-level photoelectron spectroscopy study

The surface of colloidally prepared dodecylamine/trioctylphosphine capped CdTe nanocrystals has been studied by photoelectron spectroscopy. Particles preserved in inert atmosphere, show very high photoluminescence quantum yield which is stable over time. But exposure of these nanocrystal colloids to air reduces the photoluminescence efficiency drastically. Photoelectron spectroscopy study has been performed in order to reveal, if there are any changes occurring in the chemical bonding at the nanocrystal surfaces, which might explain the observed decrease of the photoluminescence efficiency. The photoelectron spectroscopy measurements showed significant oxidation of surface Te-atoms, upon exposure to air. A comparison is drawn between the thioglycolic acid capped CdTe and dodecylamine/trioctylphosphine capped CdTe nanocrystal surfaces.