title: Solution, solid state, and film properties of a structurally characterized highly luminescent molecular europium plastic material excitable with visible light.
abstract: The synthesis and X-ray crystal structure of the ligand L (4,7-dicarbazol-9-yl-[1,10]-phenanthroline) are reported, as well as those of the molecular complex, [Eu(tta)(3)(L)] (1), (tta = 2-thenoyl trifluoroacetylacetonate). Their photophysical properties have been investigated both in solution and in the solid state. It was shown that the ligands used for designing 1 are well-suited for sensitizing the Eu(III) ion emission, thanks to a favorable position of the triplet state as investigated in the Gd(III) complex [Gd(tta)(3)(L)], (2). The low local symmetry of the Eu(III) ion shown by the X-ray crystal structure of 1 is also revealed by luminescence spectroscopy. Because of interesting volatility and solubility properties, 1 is shown to behave as a real molecular material that can be processed both by thermal evaporation and from solution. When doped in poly(methylmethacrylate) (PMMA), 1 forms air-stable and highly red-emitting plastic materials that can be excited in a wide range of wavelengths from the UV to the visible part of the electromagnetic spectrum (250-560 nm). Absolute quantum yields of 80% have been obtained for films comprising 1-3% of 1. Ellipsometry measurements have been introduced to gain information on physical data of 1. They have been performed on thin films of 1 deposited by thermal evaporation and gave access to the refractive index, n, and the absorption coefficient, k, as a function of the wavelength. A value of 1.70 has been found for n at 633 nm. These thin films also show interesting air-stability.
authors.affiliation: LPICM, Ecole polytechnique, CNRS UMR 7647, 91128 Palaiseau, France. gael.zucchi@polytechnique.edu
authors.forename: Gaël
authors.initials: G
authors.lastname: Zucchi
authors.forename: Vajjiravel
authors.initials: V
authors.lastname: Murugesan
authors.forename: Denis
authors.initials: D
authors.lastname: Tondelier
authors.forename: Dmitry
authors.initials: D
authors.lastname: Aldakov
authors.forename: Taewoo
authors.initials: T
authors.lastname: Jeon
authors.forename: Feng
authors.initials: F
authors.lastname: Yang
authors.forename: Pierre
authors.initials: P
authors.lastname: Thuéry
authors.forename: Michel
authors.initials: M
authors.lastname: Ephritikhine
authors.forename: Bernard
authors.initials: B
authors.lastname: Geffroy