Three new europium organic complex photophysical characterization and mechanism

Title: Three new europium organic complex photophysical characterization and mechanism
　　Author: Yan Alpine
　　Degree-granting units: the University of South
　　Keywords: organic europium complexes;; absorption spectra;; fluorescence spectroscopy;; energy transfer mechanism;; phenanthroline
　　Summary:
　　Organic complexes of rare earth europium fluorescence emitted by europium ion 5 D_0 → 7F_2 level of emission, the emission wavelength at 613nm or so, is a narrow band of red light-emitting material, and the electroluminescent light with high color purity , half-peak width of less than 10nm, modified ligand does not affect the light color and so on. rare earth magnets However, there is stability of the organic complexes of europium and poor film, the internal mechanism is not clear and the light-emitting electroluminescent efficiency is low and so on. Therefore, further search for novel europium organic ligand complexes to obtain new valuable, in-depth study of its luminescence mechanism is imperative.
　　In this paper, AvaSpec2048 optical spectroscopy and SP-2558 multi-spectral measurement system, the three new organic europium complexes Eu (Lx) 3phen, (including three new materials Lx represent the first ligand) and ligand at different state spectral characteristics of the experimental study and theoretical analysis, the study found:
　　1 three new materials are in the ultraviolet region 220-340nm there is a strong absorption, and with the increasing concentration of the strongest absorption peak red-shifted, while the shorter wavelength absorption peak closer to saturation. Solid samples of the best red-shifted excitation peak 350nm. Absorption spectra and excitation spectra demonstrate the absorption of three materials with the excitation spectrum is primarily the second ligand phenanthroline (phen) contribution.
　　(2) emission spectra of three kinds of materials there are five peaks with almost no changes in concentration and excitation spectra of the more acute areas: 580nm, 594nm, 613nm, 652nm and 701nm, which is Eu ~ (3) of the 4 f N Configuration 5 D_0 → 7F_0, 175 D → F_, 5 D_0 → 7F_2, 5 D 0 → 7F_3 and 5 D_0 → 7F_4 characteristic fluorescence emission peak, indicating that the main body of the complex Eu ~ (3) and phen ligands occurred energy transfer. 5 peak intensity ratio: 2:6:32:1:2, peak width Δλ = 5nm to 613nm fluorescence is far higher than other peaks. At the same time also appear in the fluorescence spectrum at 591nm, 619nm, 656nm and 691nm four relatively weak intensity of fluorescence.
　　3 three new materials, Eu ~ (3) of the fluorescence intensity ratio η = I613 / I594 are far greater than the free Eu ~ (3) the solution value, indicating that the new materials 613nm with a large ultra-sensitive transition effects, Eu ~ (3) environment symmetry lower ligand of the central Eu ~ (3) has a good sensitization.
　　4 JO rare earth crystal field theory for the successful introduction of the luminescence mechanism of the complex solution of the analysis, the ligand field of Eu ~ (3) the effective energy field perturbation effects lead to: (1) electric dipole transition 5 D_0 → 7F_2 and 5 D_0 → 7F_4 lift parity forbidden produce 613nm, 701nm fluorescence peak; (2) the http://www.chinamagnets.biz/Neodymium/Ball-Neodymium-Magnets.php state of J mixing effects arising from the 580nm and 652nm the fluorescence; (3) energy splitting to 594nm, 613nm, 652nm and 701nm peak at 591nm, 619nm, 656nm and 691nm generated at a weak secondary peak.
　　5 complexes Eu ~ (3) there are three possible mechanisms of fluorescence energy transfer process, our analysis of energy by which phenanthroline ligands for direct transfer to the triplet state of Eu ~ (3) of the excited state probability is the largest. Three kinds of fluorescent complexes of good stability, high color purity, peak width of the narrow concentration range at higher concentration quenching does not exist, there may be used in electroluminescent materials.
　　Degree Year: 2010