Optical and structural properties of ZnSe quantum dot with europium

Highlights: • The color-tunable ZnSe:Eu quantum dots (QDs) prepared in situ for the first time. • The ZnSe:Eu QDs showed ZnSe and Eu²⁺ and Eu³⁺ emission depending on Eu amount due to the concentration quenching. • The ZnSe:Eu QDs with Eu/Zn=1.5 perhaps contains more oxygen Eu₃O₄, Eu₂O₃ and EuO on the surface of Eu³⁺-doped ZnSe QDs. -- Abstract: Rare earth elements possessing unique 4f electrons have been investigated as excellent candidates for luminescent centers in doped II-VI nanocrystals, because of their abundant emission colors based on the 4–4f or 5d-4f transitions. In particular, ZnSe quantum dot (QDs) fabricated with the lanthanide Europium (Eu) can emit in both the visible and near-infrared region. In our work, the structural, morphological and optical properties were investigated the color-tunable ZnSe:Eu QDs. We focused on the ZnSe:Eu QDs synthesized by controlling Eu amount. According to the results, the optical property of ZnSe:Eu QDs showed that emission in the bluish to yellow-ocher range, and concentration quenching occurred upon increasing the Eu amount. The expected structure of the ZnSe:Eu QDs with Eu (Eu/Zn = 0.5, 1 and 1.5) was verified by XRD, TEM, XPS and gibbs free energy value using a HSC chemistry software.