Multicolor-emitting luminescent Y2O3:RE3+@SiO2-[RE3+(β-diketone)3] core@shell hybrids featuring dual RE3+ activator centers

Luminescent inorganic-organic hybrids find several applications such as in multifunctional devices or in bioimaging. In this regard, through a step-by-step process, inorganic-organic core@shell-like hybrids based on spherically-shaped Y2O3:Eu3+@SiO2-[Tb(acac)3(Salen)] or Y2O3:Tb3+@SiO2-[Eu(dbm)3(Salen)] particles with diameter of 170 nm were fabricated from Y2O3:RE3+ (RE3+ = Eu3+ or Tb3+) coated with a layer of SiO2 (2.7 nm), that was amino-functionalized, followed by imino-functionalization to get Salen ligands to which were finally bonded to [RE(β-diketonate)3] complexes (β-diketonate = acetylacetonate, acac, or dibenzoylmethanate, dbm). The core@shell architecture of the hybrids was confirmed by X-ray diffraction, FTIR and TEM. By changing the excitation pathways, the overall emitted color of both hybrids is tuned from green (Tb3+ emission) to red spectral region (Eu3+ emission), crossing the white color emission region due to the combination of the Eu3+, Tb3+ and Salen emissions. As an additional and interesting find, no energy transfer from the RE3+ in the core to the other RE3+ on the particle surface takes place, avoiding the quenching of both RE3+ luminescence. Therefore, the high 5D0 state quantum efficiency of Eu3+ (68%) and the multicolor emission qualify the hybrids for future photonic applications in multifunctional devices or in bioimaging.