Doping Gd₁₆ nanoclusters for expanded optical properties and thermometry applications

Lanthanide metal clusters are composed of rigid multinuclear metal cores encapsulated by organic ligands, which have become one of the most interesting research frontiers because of their fantastic architecture, intriguing physical and chemical properties, and potential applications. However, very little attention has been paid to exploring their potential as highly efficient optical materials. Gd₁₆ clusters are a new cluster structure that has a rich and varied coordination environment, which is highly conducive to doping and thus controlling luminescence and luminescence color modulation. We achieved green emission by doping Tb³⁺ ions and red emission by doping Eu³⁺ ions in the Gd₁₆ cluster structure. Meanwhile, we achieved red-orange-yellow color-tunable luminescence by controlling the composition of Tb³⁺ and Eu³⁺ ions. Studies on the PL properties show that Gd₁₆ clusters as the host can be used for doping and efficiently photosensitizing Tb³⁺ ions and Eu³⁺ ions. The existence of energy transfer from the ligand to Tb³⁺ ions and Eu³⁺ ions in the co-doped Ln₁₆ clusters was sufficiently demonstrated by time-resolved photoluminescence spectroscopy tests, and the energy transfer efficiency in the clusters was calculated. Furthermore, the temperature-dependent photoluminescence properties of these clusters were investigated to determine their potential as luminescent thermometers.