Incorporation and Luminescence of Yb³⁺ in CdSe Nanocrystals

Doping quantum dots (QDs) with lanthanide ions is promising to combine the efficient sharp line emission of lanthanides with the strong and size-tunable absorption of QDs. Incorporating lanthanide ions in II–VI QDs remains challenging, however, here we report successful coupling of CdSe QDs with the lanthanide ion Yb³⁺. Our spectroscopic results demonstrate that Yb³⁺ ions are first adsorbed on the CdSe surface and subsequently incorporated in the nanocrystalline semiconductor particles by growing a Se shell. Evidence for incorporation is provided by the fine structure of the CdSe QDs absorption in the excitation spectrum of the Yb³⁺ emission at 1000 nm and the long lifetime of the Yb³⁺ emission after shell overgrowth. Sensitized Yb³⁺ infrared emission may find application in optical amplifiers, solar concentrators, and bioimaging. The method described is a promising strategy for incorporating lanthanide ions in other II–VI QDs.