Application Of Red Light Emitting Material For White LED

Rare earth luminescent materials have wide application in our life and production. In this work, we have studied the fluorescence properties of europium complexes with different substituents in aromatic carboxylic acid, the effect of DMF on the luminescence properties of rare earth complexes. The results are summarized as follows:1. Nine ternary complexes of europium with benxoic acid, 4-tert-butylbenzoic acid, 3-methylbenzoic acid, 2,5-dichlorobenzoic acid, 4-chlorobenzoic acid, 3,5-dinitrobenzoic acid, salicylate and sodium salicylate as the first ligand and phenanthroline as the second ligand were synthesized. They are all characterized by IR, XRD and Fluorescence Spectra. Fluorescent intensity of complexes containing an electron withdrawing group decreases and the fluorescence intensity of the complexes containing electron donating groups increased. In addition, when the lowest triplet energy level of the ligand is less than or much higher than the excited states of the central ion, the energy cannot be efficiently transmitted, then it cannot show the characteristic spectrum of the central ion. We also embedded europium benzoate complex into 13X-zeolite, SBA-15 molecular sieve and Si O2 aerogel composites respectively, hybrid materials were prepared and tested for their fluorescence properties and thermal stability.2. This section discusses the changes of excitation spectra of the mixed solution when different quality of Eu(DBM)3phen powders were dissolved in dimethylformamide(DMF). We found that with increasing quality of Eu(DBM)3phen, excitation peak red-shifted from the original 260-420 nm red-shifted at 427-460 nm and the emission spectrum peak position unchanged. This chapter also discusses the reasons of the excitation spectra changing from three aspects. In first, how the Eu(DBM)3phen existing state is in DMF solution, followed by the effects of diffent solvent on excitation spectra of the complexes, and finally with the impact of the ligand structure. Lastly, we have combined Eu(DBM)3phen with epoxy resin to prepare a light emitting device, the resulting device has a good luminescent properties, high transparency, high color purity and good lighting at a lower voltage. We have also combined Eu(DBM)3phen with EVA to prepare transparent Eu(DBM)3phen/EVA film showed good transparency.