Color tunable white LEDs based on low sintering temperature Phosphor−in−Glass

A low sintering temperature glass based on B2O3–Na2O–Al2O3 system was studied as a matrix for embedding phosphors to fabricate color tunable white LEDs. Red-emitting-phosphor-in-glass (R−PiG) was prepared by co-sintering glass frits and CaAlSiN3:Eu2+ (CASN:Eu2+) phosphors at 480 °C. Then, Y3Al5O12:Ce3+ (YAG:Ce3+) yellow phosphors were added to obtain white light. The white LEDs by YAG&CASN-based PiG and 450 nm LED chip with correlated color temperature (CCT) of 3000 K–5700 K were successfully fabricated by tuning the ratio of glass to phosphors, the proportion of two phosphors, and the thickness of PiG. The fabricated wLEDs all have a color rendering index (CRI) above 70, with a maximal luminous efficacy of 84.5 lm/W. Furthermore, this study observed a great 51 nm redshift of emission spectrum by doping 1–2 wt% CASN:Eu2+, which inspires a practical manufacturing method to obtain high-power light sources with better CRI at a lower cost. •B2O3–Na2O–Al2O3 glass system was used to fabricate phosphor-in-glass, that could be applied to high-power light source.•The PiG can be sintered at a low temperature of 480 °C, which causes less thermal damage to the red phosphor CaAlSiN3:Eu2+.•The Red-emitting PiG shows a high luminous efficacy of 29.91 lm/W when mounted on a blue LED.•Moreover, a great 51 nm redshift of emission spectrum was observed by doping 1–2 wt% CASN Eu2+ to the YAG:Ce3+-based PiG.•A series of white LEDs were fabricated with CCT range from 3000 K to 5700 K, and all of them had a CRI higher than 70.