Preparation, Characterization And Application Of Fluorescence Hydrotalcite-like Materials

This thesis is mainly composed of four sections:(1) The series of modified fluorescent hydrotalcite-like compounds are synthesized by coprecipitation method. In the samples, the metal ions are dispersed into the hydrotalcite-like layers; some appropriate ligands are dispersed into the anions among the interlayer region. At the same time, a suitable silane coupling agent or surfactants modification is also added. The metal ions in the layers are coordinated by ligands through the oxygen and nitrogen atoms. The samples are characterized by PL, XRD, FT-IR, TG and SEM, and their properties and structure are determined. The results indicated that under the excitation of UV light, the samples can exhibit bright red, green, and blue light, respectively. It shows that the fluorescence quenching effect due to aggregation of irradiant center may be prevented efficiently, because the metal ions are dispersed in layers uniformly. Moreover, the particular coordination structure may increase the asymmetry of irradiant center, leading to enhance the fluorescence intensity of this kind of material. Additionally, the protection effect of layer structure may also enhance the thermal stability. The modified compounds show higher fluorescence quantum yield and enhanced thermal stability. The modification also can improve interface bonding capacity of compounds with silica gel.(2) To obtain a white-light emitting hydrotalcite-like compounds by simultaneously mixing red, green and blue-emitting fluorescent hydrotalcite-like compounds according to certain proportion, based on the principle of tricolor overlay. Excited by365nm UV light, the simultaneous emission bands of this material are located in the red, green, and blue regions, combined to give a white emission CIE (0.3180,0.2725).(3) The series of fluorescent hydrotalcite-like compounds/silicon resin nanocomposites are prepared using the intercalation in situ polymerization method. The nanocomposites exhibit excellent dispersibility. Their properties combined properly the thermal stability of the inorganic materials as long as the processability of the polymers. The nanocomposites will help to settle some shortcomings of the existing LED, such as poor thermal resistance and the spatial color uneven distribution. This research can provide useful information for the application of the polymer/inorganic nanocomposites in LED and promote the practical application of LED solid-state lighting.(4) Above fluorescent hydrotalcite-like materials were applicated in light-emitting diodes.