Broad-Band and Stable Phosphor-in-Glass Enabling Ultrahigh Color Rendering for All-Inorganic High-Power WLEDs
Yang Peng, Hao Wang, Jiaxin Liu, Qinglei Sun, Yun Mou, Xing Guo
Abstract
All-inorganic color converters are promising luminescent materials for high-power white lighting due to their excellent heat resistance and high thermal conductivity. However, the low color rendering of converters limits their applications in high-quality lighting. Herein, a broad-band and stable phosphor-in-glass (PiG) was developed for high-power white light-emitting diodes (WLEDs). This PiG converter was fabricated by sintering a green/red phosphor glass film on a glass plate with a patterned metal layer. The green Y3Al3.08Ga1.92O12:Ce3+ phosphor has a broad emission, which compensates for the cyan cavity between blue and green emission spectra, and then produces full-spectrum white light combined with the red CaAlSiN3:Eu2+ phosphor. The all-inorganic WLEDs were realized by welding the PiG on a substrate. The optical performance of PiG-based WLEDs was optimized by varying the film thickness. At the film thickness of 150 μm, the fabricated WLEDs achieve ultrahigh color quality of color rendering index (CRI) values (Ra = 95.4, R9 = 95.1, and R13 = 97.3) and fidelity/gamut index values (Rf = 91 and Rg = 102). The corresponding luminous efficacy (LE) and correlated color temperature (CCT) are 65 lm/W and 5260 K, respectively. After aging at 100 °C for 200 h, the PiG-based WLEDs exhibit low efficiency loss and stable color quality compared with the traditional phosphor-in-silicone (PiS)-based WLEDs. The prepared PiG is a broad-band and stable converter enabling ultrahigh color rendering for high-power white lighting.