Preparation And Characterization Of Phosphors For LED

Green lighting style was put forward at the background of global wanning and energy saving. White LED (light-emitting diode) is recognized as the green lighting product and will substitute the traditional bulbs. In present, the way employing an InGaN/GaN LED chip coated by YAG (yttrium aluminum garnet, Y₃Al₅O₁₂) yellow phosphors is the main way to get w-LED. As a result, YAG yellow phosphor becomes critical for green lighting. In this paper, the YAG: Ce³⁺ phosphors were synthesized by traditional solid-state reaction, and the possible ingredients which may affect the luminescence property were investigated in detail.Ingredients including sintering temperature, Ce³⁺ concentration, as well as the doping of Ga³⁺, and Gd³⁺ are investigated in detail, in order to make the property of the experimental product consistent with the application.Using solid-state reaction method synthesized the YAG: Ce³⁺ yellow phosphor powders at 1500℃with the assistance of flux. The samples were characterized by XRD, SEM and fluorescence spectrometer. The classic absorption and emission of Ce³⁺ are cleanly observed, and the luminescence principle of Ce³⁺ in the host of YAG was testified.Microwave assisted synthesis together with heat-treatment at a high temperature are employed to prepare the phosphor of terbium-aluminium garnet co-doped by Ce³⁺ and Eu³⁺ (TAG: Ce, Eu). The particles of the prepared samples are clear and smooth. Most particles have the size of less than 2 urn. The powder has slightly agglomeration. The classic absorption and emission of TAG: Ce, Eu are cleanly observed. Compared with the traditional high-temperature solid-state synthesis, this route employed in this investigation has the advantages of easier synthesizing, energy saving and environmental protecting. The time of heat-treatment should be 2-3 h. The reaction pathway has been analyzed, implying that the diffusion coefficient of aluminum is bigger than that of terbium, in Tb₂O₃—Al₂O₃ system.