蓝光LEDs的转换荧光粉发光效率的测量

Measurements of Luminous Efficacies of Conversion Phosphors for Blue Emitting LEDs

本文研究了YAG：Ce荧光粉的色氟红移的现象。当YAG晶格点阵中的Y被Gd激发或添加了Pr作为Ce的共同催化剂时就会发生这种现象。测量了在（Y，Gd）AG：Ce和YAG：Ce，Pr荧光粉样品内部的效率，其激发光线的波长为470nm。其结果表明这两种荧光粉的发光效率分别随着Gd和Pr聚集而降低。SrGa2S4：Eu。是另外一种常用的转换蓝光LED的颜色的荧光粉。室温下，这种荧光粉效率很高，理论上其发光效率比YAG：Ce的发光效率高出33％。对这种荧光粉效率的测量结果表明其制作过程是影响性能的主要因素。将这种荧光粉印刷在放在一个或多个蓝光LED前面的屏幕的表面，测得其发光效率高达364lm／W。

In this work we investigate the shift of the colour point of the YAG.Ce phosphor towards the red when Y is substituted by Gd in the YAG lattice or when Pr is added as a co-activator with Ce. We also describe efficiency measurements carried out on in-house samples of （Y,Gd）AG： Ce and YAG. Ce, Pr phosphors when excited with 470 nm light. We show herein that the luminous efficacies of the （Y,Gd）AG.Ce and YAG：Ce,Pr phosphors decrease with Gd and Pr concentrations, respectively. Another phosphor that we and others have used for colour conversion of blue LED light is SrGa2S4：Eu. At room temperature this phosphor is very efficient, theoretically having a luminous efficacy that is more than 33% higher than that of YAG：Ce. Luminous efficacy measurements on this phosphor show that the method of preparation is a major factor in the performance of the phosphor. When applied as an external screen phosphor in front of one or more blue LEDs, we have measured luminous efficacies up to 364 lm/W.