Facile one-step fabrication of 2-layered and 4-quadrant type phosphor-in-glass plates for white LEDs: an insight into angle dependent luminescence

Abstract

Phosphor-in-glass (PiG) when used in combination with a blue light emitting diode (LED) chip in a remote phosphor configuration offers precise tuning and yields higher luminous efficiencies at elevated temperatures, compared to the conventional conformal LED packaging. However, drawbacks such as spectral overlapping of the constituent phosphors and resultant reabsorption remain unresolved in multi phosphor color conversion plates. These issues were solved up to a desired extent by arranging different color-emitting PiGs, via cutting and reassembly. However, the interface of the multicolored plates acted as a dissipative layer. In this work, a novel fabrication technique was proposed to overcome this drawback by eliminating the interfacial layer through a one-step process. PiGs were fabricated using glass frits at a low softening temperature of 600 °C. As a result, a higher efficacy of the studied prototypes, i.e., a horizontal 2-layered PiG and a 4-quadrant PiG, was obtained as compared with their counterparts. The angular dependency of the luminescence of the segmented 4-quadrant type PiG was studied, and the results were discussed.