Single-Component White Emitting Silicate Glass Triply Activated by Ce3+/Tb3+/Mn2+ for Organic-Resin-Free White LEDs

Thermal management is still a great challenge for high-power phosphor-converted white-light-emitting diodes (pc-WLEDs) intended for future general lighting. Luminescent glass based WLEDs (LG-WLEDs) are strongly expected to be an interesting and excellent alternative approach to traditional pc-WLEDs fabricated by combining InGaN based LED chips, with phosphor and organic resin. In the past years, many efforts have been made to develop luminescent glasses for LG-WLEDs. However, some of these glasses are poor in mechanical and chemical stability, some cannot be excited effectively owing to weak f-f absorption, and others are not very suitable for UV-LED chips ascribed to their maximum excitation wavelengths in deep UV. [1]

In this paper, a series of single-component white emitting silicate SiO₂–Li₂O–SrO–Al₂O₃–K₂O–P₂O₅: Ce³⁺, Tb³⁺, Mn²⁺(SLSAKP: Ce³⁺, Tb³⁺, Mn²⁺) glasses that simultaneously play key roles as a luminescent convertor and an encapsulating material for WLEDs were prepared via the conventional melt-quenching method. The as-synthesized SLSAKP: 0.3%Ce³⁺, 2.0%Tb³⁺, 2.0%Mn²⁺ glass shows good thermal stability, inconspicuous chromaticity shift, better high-temperature resistance, and higher thermal conductivity. These are rare but desirable characteristics that are not present in the phosphors used as luminescent convertor and the epoxy resin used as the encapsulating material in pc-WLEDs. Luminescent glass (LG-) WLEDs based on SLSAKP: 0.3%Ce³⁺, 2.0%Tb³⁺, 2.0%Mn²⁺glass and UV-COB was successfully fabricated. These results indicate that SLSAKP: Ce³⁺, Tb³⁺, Mn²⁺ glass may serve as a potential bifunctional white-light-emitting materialfor LG-WLEDs pumped by UV-LED chips, especially high-power UV-COB.  

Fig. 1. Photographic images of the mirror-polished (left) and rough-polished (right) SLSAKP: Ce³⁺, Tb³⁺, Mn²⁺glasses: (a) under white-emitting fluorescent lamp; (b) under 365 nm UV lamp. (c) The conceptual and actual fabrication process

References:

1. Xuejie Zhang, Lin Huang, Fengjuan Pan, Mingmei Wu, Jing Wang*,Yan Chen, Qiang Su, ACS Appl. Mater. Inter. 2014, 6 (4), 2709–2717.