Two-layered Lu3Al5O12:Ce/ Y3Al5O12:Ce composite phosphor converter for white light-emitting diode devices

Abstract

Thermal management poses a significant challenge for conventional phosphor-converted white LEDs (pc-WLEDs), thereby affecting their overall efficiency. Single crystal phosphors (SCPs), such as Y₃Al₅O₁₂:Ce (YAG:Ce), exhibit enhanced efficiency and thermal stability in comparison to conventional powder phosphors. The garnet Lu₃Al₅O₁₂:Ce (LuAG) has been characterized as a green phosphor with even higher than YAG:Ce temperature stability, making it suitable for use in high-power WLEDs. However, there are some difficulties in obtaining suitable components with longer emission wavelengths in LuAG:Ce phosphors. As a way to solve this issue, the article suggests the growth of LuAG:Ce single crystalline films onto YAG:Ce substrates, thereby producing a composite color converter that possesses adjustable parameters. This paper presents a comprehensive analysis of the fabrication process as well as the characteristics of a two-layered LuAG:Ce film/YAG:Ce substrate composite color converter. The results of investigations of the structural, luminescence and photoconversion characteristics of composite color converters were presented as well. This study includes also consideration of the effect of varying LuAG:Ce film thicknesses and concentrations of Ce³⁺ in YAG:Ce substrates on photoconversion characteristics of composite converters.