Thermally stable WLEDs with excellent luminous properties by screen-printing a patterned phosphor glass layer on a...

In order to improve the luminous properties and thermal reliability of white light-emitting diodes (WLEDs), we proposed a promising phosphor-in-glass (PiG) converter, which was prepared by screen-printing a patterned phosphor glass layer on a microstructured glass plate. The patterned layer achieves four-quadrant phosphor geometry based on separated yellow Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce³⁺) and red CaAlSiN₃:Eu²⁺ (CASN:Eu²⁺) phosphor parts. Comparison experiments between the patterned PiG with and without a microstructure array (MSA) were conducted at different phosphor glass thicknesses. Consequently, for the phosphor glass thickness of 75 μm, the luminous efficacy (LE) of the proposed PiG is increased by 12.5% owing to the reduction of total internal reflection at the glass-air interface by the MSA, and the corresponding correlated color temperature (CCT) and color rendering index are 3701 K and 85.1, respectively. Furthermore, the CCT deviations of patterned PiG are reduced from 405 to 115 K and 1004 to 548 K by the MSA at the average CCTs of 3800 K and 5500 K, respectively. The results demonstrate that the proposed PiG converter can improve the LE and angular color uniformity of multi-component PiG-based WLEDs simultaneously.