Synthesis And Modification Of Core/Shell Nanostructuer Quantum Dots For The Fluorescent Films Preparation

White LEDs has higher color quality and photoelectric conversion efficiency Compared with conventional lighting technology, which is the trend of lighting field. White LEDs on the market mainly use blue diode chips and yellow rare-earth-based phosphors to produce white light. The rare-earth-based phosphors have a large particle size, which cause serious Scattering. On the other hand, its fluorescence wavelength is difficult to be adjusted and fluorescence quantum yield isn't ieal either. All these shortcomings cause strong urges to improvement its color rendering index and efficiency. Quantum dots have excellent optoelectronic properties, which wavelength could be adjusted easily by changing its composition or particle size and could obtain very high fluorescence quantum yield. Moreover, because of very small particle size, the light scattering loss could reduce significantly. It has broad prospects for application in the field of white LEDs based on the above mentioned advantages of quantum dots. However, at this stage the high toxicity, poor long-term stability and dispersion in medium, limits its application. Therefore, quantum dots as down-conversion materials need to improve the fluorescence quantum yield, it is also necessary to reduce the toxicity, enhance the long-term stability and dispersion in the medium.In this dissertation, we carried out work in the following three aspects.?1? The hydrophobic ?-? Group quantum dots surface modification by Silica. First, we obtained the amphiphilic poly lauryl methacrylate?abbreviated as APLMA? solution by solution polymerization process. We mixed the APLMA solution with the toluene solution of hydrophobic ?-? Group quantum dots to coat the quantum dots. Then we added ammonia to precipitate, then washed and dispersed by deionized water to obtain phase transfered quantum dot aqueous solution. We used sol-gel method to coat the water-soluble quantum dots with silica. By studying the influence of APLMA molecular weight, the amount of ammonia, alcohol-water ratio, the silane coupling agent for forming quantum dot- silica composite particles' morphology, we obtained the QD-APLMA-SiO₂ composite particles having relatively uniform particle size and good dispersion. The composite quantum dots mostly preserved the fluorescence feature of the QDs before treatment.?2? Preparation and Application of the ?-? Group fluorescent quantum dots films. Selection of ?-? Group QD-APLMA-SiO₂ quantum dots composited with the silicone or epoxy resin, we obtained films of different PL intensities. We effectively changed the correlated color temperature of the cool white chip by using red QD-APLMA-SiO₂ quantum dots epoxy films of different intensities.?3? Synthesis of the Cu: Zn-In-S quantum dots, preparation and application of its fluorescent films. We synthesised Cu: Zn-In-S quantum dots by one pot non-injection method. By adjusting the Zn/In molar ratio of the precursor we obtained green and orange-red doped quantum dots. We also studied the effects of Cu doped amount on the fluorescence, the optimum reaction temperature and time of the nucleation stage and shell stage of different Zn/In molar ratio. We Prepared green and red films of different PL intensities by mixing Cu: Zn-In-S quantum dots with Styrene-acrylate copolymer. Finally, we got white light having a correlated color temperature of 6917 K.