||In recent years, due to the rising global environmental consciousness, solid-state lightings with high efficiency, low power consumption and long lifetime have become promising for the next-generation of lighting applications. In this dissertation, we utilize glass phosphors as the color converted layer for LED (Light-Emitting Diode) and OLED (Organic Light-Emitting Diode) devices. We propose the solutions for realizing white LEDs with wide range of CCT and highly efficient white OLED.|
In the first part of this dissertation, we used glass phosphor as the color converted layer for white LEDs. The glass phosphors were made by dispersing green (Lu3Al5O12:Ce3+), yellow (Y3Al5O12:Ce3+) and red (CaAlClSiN3:Eu2+) phosphor crystals with a suitable proportion into sodium-based glass matrix. The CIE coordinates of the white LEDs with the 0.95 mm thick glass phosphor composite of LuAG:Ce and CASN:Eu in a doping weight ratio of 8:2 was (CIEx,y=0.335,0.342) and the CRI of the white LEDs reached 87. Through adjusting the thickness of the glass phosphors, the white LEDs exhibit CCT ranging from 4246K to 6711K with CRI ranging and yield luminous efficiency up to 80 and 90 lm/W, respectively. The glass phosphor in this work provides an effective way for white LEDs to achieve both chromaticity tailorability and high efficiency.
In the second part of the dissertation, we utilized glass phosphor as the substrate for white OLEDs. Prompted by the strong light-scattering ability of the fluorescent substrate (glass phosphor), it is possible to serve as a scattering color-conversion layer for white OLEDs. At a driving voltage of 13.6V, the CIE coordinates, CCT, and CRI of the white OLEDs with the substrate doped with YAG:Ce and CASN:Eu in a weight ratio of 3:5(Y3R5) were (CIEx,y=0.339,0.409), 5313K, and 81, respectively. The device exhibited maximum external quantum efficiency of 7.2%, maximum luminance of 6819 cd/m2. The maximum current efficiency and power efficiency of the device were 7.9 lm/W and 17.1cd/A, respectively. The device showed an excellent color rendering and color stability. The CIE coordinates of the device changed slightly with the driving voltage. In this work, we proposed a simplified white OLEDs composed by a blue OLED and a fluorescent substrate. Benefiting from its simplified device structures, the device exhibited excellent color stability and color rendering, this contribution shows the great potential of this kind of white OLEDs for the high color-quality lighting applications.