resumo
Interest in lanthanide-containing organic-inorganic hybrids has grown I considerably during the last decade, with the concomitant fabrication of materials with tunable attributes offering modulated properties. The potential of these materials relies on exploiting the synergy between the intrinsic characteristics of sol-gel derived hosts (highly controlled purity, versatile shaping and patterning, excellent optical quality, easy control of the refractive index, photosensitivity, encapsulation of large amounts of isolated emitting centers protected by the host) and the luminescence features of trivalent lanthanide ions (high luminescence quantum yield, narrow bandwidth, long-lived emission, large Stokes shifts, ligand-dependent luminescence sensitization). Promising applications may be envisaged, such as light-emitting devices, active waveguides in the visible and near-IR spectral regions, active coatings, and bio-medical actuators and sensors, opening up exciting directions in materials science and related technologies with significant implications in the integration, miniaturization, and multifunctionalization of devices. This review provides an overview of the latest advances in Ln(3+)-containing siloxane-based hybrids, with emphasis on the different possible synthetic strategies, photoluminescence features, empirical determination of the radiative and nonradiative transition rates, excited-state quantum efficiency, overall emission quantum yield and Omega(2,4,6) intensity parameters, and a quantitative description of host-to-Ln(3+) energy transfer processes. A summary includes future requirements, aims, and trends of this fascinating area, revising concurrently some of the main photonic applications.
palavras-chave
RARE-EARTH IONS; EMISSION QUANTUM YIELDS; FUNCTIONALIZED ORGANIC/INORGANIC HYBRIDS; CARBOXYLIC-ACID SOLVOLYSIS; NEAR-INFRARED LUMINESCENCE; FIELD STRENGTH PARAMETER; MOLECULAR-BASED HYBRIDS; SHORT POLYETHER CHAINS; FULL-COLOR PHOSPHORS; SOL-GEL GLASSES
categoria
Chemistry; Science & Technology - Other Topics; Materials Science; Physics
autores
Carlos, LD; Ferreira, RAS; Bermudez, VD; Ribeiro, SJL
nossos autores
Luís Carlos
Professor Catedrático
Maria Rute de Amorim e Sá Ferreira André
Professor Catedráticoagradecimentos
The support of NoE FAME, Fundacao Para a Ciencia e a Tecnologia (Portuguese agency), FEDER, (PTDC/CTM/72093/2006 and V.S/A0067/2005), FAPESP and CNPq (Brazilian agencies), and CAPES-GRICES Brazil-Portugal cooperation program is gratefully acknowledged. The authors thank S. C. Nunes and M. Fernandes (CQ-VR, Vila Real), E. Pecoraro (IT, Aveiro), and P. P. Lima, and S. S. Nobre (CICECO, Aveiro) for providing experimental data.