Research On White LED Devices Based On Phosphor Materials

With the continuous improvement of market requirements,the heat dissipation and reliability of high-power LED products limit the rapid development.The main problems affecting the life and efficiency of LEDs come from the heat quenching and light decay,which caused by the heat generated in LEDs.At present,there are many inorganic materials to solve related problems,such as phosphor glass,phosphor ceramics,phosphor crystallites,etc.Using phosphor materials for LED packaging can greatly improve the stability and life of LED products.In this paper,a series of phosphors,phosphor films and phosphor ceramics materials were prepared.The effects of ion doping on the thermal stability and reliability of the phosphors,phosphor films and phosphor ceramics,and the effects of three different packaging methods on the photoelectric performance of the packaged LED device are mainly investigated.The main research work is as follows:1.Europium doping strontium silicate barium phosphors(Ba_xSr_2-xSiO₄:0.02Eu²⁺?x = 0,0.2,0.5,0.8,1,1.5 and 2?)were successfully prepared by conventional solid-state reaction technology,and the phosphor films are prepared from the synthesized Bax Sr2-x Si O4:0.02Eu²⁺?x = 0,0.2,0.5,0.8,1,1.5 and 2?phosphors by a simple spin coating methods.Then,the relationship between the Ba²⁺ ion content of Bax Sr2-x Si O4:0.02Eu²⁺ phosphor in phosphor film and the thermal stability and reliability of the phosphor film was investigated by the high temperature thermal stability test,xenon lamp aging test,high temperature-high humidity test and thermal cycling test.2.Yttrium Aluminum Garnet transparent ceramics with different Gd³⁺ concentrations??Ce0.001 Gdx Y0.999-x?3Al5O12?ceramics were prepared by the conventional solid state reaction technology and vacuum sintering method,and the ceramic-based LEDs with blue LED were prepared by flip chips and Chip on board package.The extreme circumstance of-40°C and 150°C alternate environments,high humidity and high temperature as well as xenon lamp aging test for a long time are mentioned to explore the reliability of phosphor ceramics,respectively.And the thermostability and the effect of Gd³⁺ doping on the PL properties of ceramics were also investigated.What is more,the effects on the optical performance of the ceramic-based LEDs have been also investigated.3.Ce: Gd YAG ceramics and Ca Al Si N₃: Eu²⁺ phosphor were fabricated by solid-state reaction.Ca Al Si N₃: Eu²⁺ phosphor films with different content were manufactured on Ce: YAG ceramic by the spin-coating method.Finally,the effects of Ca Al Si N₃: Eu²⁺ phosphor content in phosphor film and three different packaging methods on the photoelectric performance of LED devices were investigated.