Visible-emitting hybrid sol–gel materials comprising lanthanide ions: thin film behaviour and potential use as phosphors for solid-state lighting
Résumé
The synthesis and characterization, as well as the film-forming and luminescent properties of four visible-emitting hybrid organic-inorganic sol-gel materials are reported. They show thermal stability up to 165°C. Deposition conditions were optimized to coat these materials as homogeneous and transparent thin films (~50 nm) with smooth surface, as probed by AFM. They were specifically designed to emit the primary colors. The blue-emitting material 1 was made up of a polyfluorene derivative embedded in a silica matrix, while the green (2) and red (3)-emissive materials comprise the TbIII and EuIII ions bound to the matrix, respectively. The films showed relatively high emission quantum yields efficiencies, with values of 19% (blue), 46% (green), and 21% (red). The three emitters were used to design a single emissive material (4) that showed emission colors from yellow-green to blue in a wide range of excitation wavelengths (254-380 nm). In particular, white light was obtained after excitation at 340 nm.