Measurements of Luminous Efficacies of Conversion Phosphors for Blue Emitting LEDs
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.
YAG: Ce Pr Phosphors (Y Gd)AG: Ce Phosphors,Srga2S4:Eu phosphors,Luminous Efficacy,PcLED
Jack Silver Robert Withnall Anthony Lipman
Wolfson Centre for Materials Processing, Brunei University,Uxbridge, Middlesex UB8 3PH, UK
国际会议
上海
英文
1074-1078
2007-03-12（万方平台首次上网日期，不代表论文的发表时间）