Magnetic, Photo- and Electroluminescent: Multifunctional Ionic Tb Complexes

In the search for new multifunctional materials, particularly for application in solid-state lighting, a set of terbium salicylato (Sal) complexes of general composition [Cat][Tb(Sal)₄] with the commonly ionic liquid-forming (IL) cations [Cat] = (2-hydroxyethyl)trimethylammonium (choline) (Chol⁺), diallyldimethylammonium (DADMA⁺), 1-ethyl-3-methylimidazolium (C₂C₁Im⁺), 1-butyl-3-methylimidazolium (C₄C₁Im⁺), 1-ethyl-3-vinylimidazolium (C₂Vim⁺), and tetrabutylphosphonium (P₄₄₄₄⁺) were synthesized. All Tb compounds exhibit strong green photoluminescence of high color purity by energy transfer from the ligand in comparison with what the analogous La compounds show, and quantum yields can reach up to 63% upon ligand excitation. When excited with an HF generator, the compounds show strong green electroluminescence with the same features of mission. The findings promise a high potential of application as emitter materials in solid-state lighting. As an additional feature, the Tb compounds show a strong response to applied external fields, rendering them multifunctional materials.