Ultra-compact warm WLEDs fabricated by multi-color phosphor-in-glass directed bonding on flip-chip UV-LEDs

Abstract

In this paper, we prepared a multi-color phosphor-in-glass (PiG) for the packaging of warm white light-emitting diodes (WLEDs). The multi-color PiG yields a red, green, and blue (RGB) phosphors glass layer, which was screen-printed and co-sintered on a glass plate at the temperature of 600°C. The RGB-PiGs were directly bonded on flip-chip ultraviolet (UV) LEDs. By controlling the thickness of RGB layer, the luminous properties of RGB-PiG based WLEDs are adjusted. When the RGB layer thickness is 75 µm, the RGB-PiG based WLED achieves a warm white light, and the corresponding luminous efficacy (LE), correlated color temperature (CCT), and color rendering index (CRI) are 27.76 lm/W, 4245 K, and 92.6, respectively, at the current of 350 mA. The multi-color PiG provides an effective approach to achieve warm WLEDs with high CRI for display and indoor lighting applications.