Color‐Tunable Luminescence of Eu‐Doped LaF3 Particles Sensitized by d–f Energy Transfer from a Two‐Photon Absorbing Ir(III) Complex

• Published in: Advanced optical materials 2024-06, Vol.12 (18), p.n/a
• Main Authors: Ye, Yating, Jiménez, Juan‐Ramón, Quesada‐Moreno, María Mar, Navarro, Amparo, Ortega‐Naranjo, Esther M., Orte, Angel, Herrera, Juan Manuel
• Format: Article
• Language: English
• Subjects: Absorption spectra; Color; d–f energy transfer; Emission spectra; Energy transfer; Europium; Excitation; iridium luminescence; lanthanide nanoparticles; Lanthanum; Lanthanum fluorides; Phosphorescence; photoluminescence lifetime imaging microscopy; Photons; two‐photon excitation
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202302954

The surface of Eu0.3La0.7F3 submicron particles is functionalized with a blue‐emitting Ir(III) complex (1) specifically designed to coordinate lanthanide(III) ions efficiently through a carboxylic unit. In this Eu0.3La0.7F3@1 composite, the Ir(III) complexes are randomly coordinated to either superficial La(III) ions or Eu(III) ions (Ir‐Lasurface and Ir‐Eusurface pairs, respectively) and its color emission, a balance between blue (Ir‐based) and red (Eu‐based) light, can be tuned as a function of the excitation wavelength. Irradiation at the maximum of the excitation band in 1 promotes blue emission from Ir‐Lasurface pairs and red emission from Eusurface ions sensitized by Ir → Eusurface energy transfer (EnT). At λexc = 396 nm (maximum of the Eu(III) 5L6 ← 7F0 absorption band) the red emission from inner Eu(III) ions becomes dominant. Excitation of 1 can also be achieved by two photon‐absorption (TPA) since this complex has a moderate cross‐section of σ2 = 9.4 ± 1.0 GM at 780 nm (σ2 = 5.8 ± 0.6 GM at 800 nm). Phosphorescence lifetime imaging (PLIM) allows the emission of individual particles to be visualized and the Ir‐, Eusurface‐, and Eucore‐based emissions can be distinguished due to the significant differences in their respective emission lifetimes. A two‐photon absorbing Ir(III) complex is used as an antenna to sensitize Eu(III)‐based emission from Eu0.3La0.7F3 particles. The resulting Eu0.3La0.7F3@Ir composite, in which the existence of Ir → Eu energy transfer is demonstrated, exhibits bright and color‐tunable light emission under both UV–vis and near‐infrared excitation. Its emission is analyzed on a particle‐by‐particle basis by photoluminescence lifetime imaging microscopy.