Decorated Quantum Dots as sensitizers for lanthanide ions: Preparation, characterization and optical properties

Lanthanide ions are well-known for their lumuniscence properties. They present low molar absortivities, usually leading to inefficient direct excitation of the emissive states. In this work we explore the use of decorated quantum dots to sensitize the emission of lanthanide ions. By using a bifunctional thiol capping ligand with carboxylic groups, we functionalized ZnS or CdS QDs and coordinate Eu(III) or Tb(III) ions to these ligands, aiming to sensitize the lanthanides via Förster Resonance Energy Transfer (FRET). The decorated QDs were synthesized through different precipitation methods and thoroughly characterized using UV-Vis, DLS, IR spectroscopy, XRD, and elemental analysis. The fluorescence profiles of the quantum dots were studied under different conditions, both with and without the addition of the lanthanide ions Eu(III) or Tb(III). The use of co-ligands to complete the coordination sphere of the lanthanide ions was also explored. The results show a promising enhancement of the lanthanide emission.