Highly Thermally Stable Single-Component White-Emitting Silicate Glass for Organic-Resin-Free White-Light-Emitting Diodes

Abstract

Thermal management is still a great challenge for high-power phosphor-converted white-light-emitting diodes (pc-WLEDs) intended for future general lighting. In this paper, a series of single-component white-emitting silicate SiO2-Li2O-SrO-Al2O3-K2O-P2O5: Ce(3+), Tb(3+), Mn(2+) (SLSAKP: Ce(3+), Tb(3+), Mn(2+)) glasses that simultaneously play key roles as a luminescent convertor and an encapsulating material for WLEDs were prepared via the conventional melt-quenching method, and systematically studied using their absorption spectra, transmittance spectra, photoluminescence excitation and emission spectra in the temperature range 296-498 K, decay curves, and quantum efficiency. The glasses show strong and broad absorption in 250-380 nm region and exhibit intense white emission, produced by in situ mixing of blue-violet, green, and orange-red light from Ce(3+), Tb(3+), and Mn(2+) ions, respectively, in a single glass component. The quantum efficiency of SLSAKP: 0.3%Ce(3+), 2.0%Tb(3+), 2.0%Mn(2+) glass is determined to be 19%. More importantly, this glass shows good thermal stability, exhibiting at 373 and 423 K about 84.56 and 71.02%, respectively, of the observed room temperature (298 K) emission intensity. The chromaticity shift of SLSAKP: 0.3%Ce(3+), 2.0%Tb(3+), 2.0%Mn(2+) is 2.94 × 10(-2) at 498 K, only 57% of the commercial triple-color white-emitting phosphor mixture. Additionally, this glass shows no transmittance loss at the 370 nm emission of a UV-Chip-On-Board (UV-COB) after thermal aging for 240 h, compared with the 82% transmittance loss of epoxy resin. The thermal conductivity of the glass is about 1.07 W/mK, much larger than the 0.17 W/mK of epoxy resin. An organic-resin-free WLEDs device based on SLSAKP: 0.3%Ce(3+), 2.0%Tb(3+), 2.0%Mn(2+) glass and UV-COB is successfully demonstrated. All of our results demonstrate that the presented Ce(3+)/Tb(3+)/Mn(2+) tridoped lithium-strontium-silicate glass may serve as a promising candidate for high-power WLEDs.

A high color purity red emitting phosphor CaYAlO4:Mn4+ for LEDs

“…QE is defined as the ratio of the number of emitted photons (I em ) to the number of absorbed photons (I abs ), and can be calculated by the following equation [22]. where E R , E S are the spectra of the excitation light without and with the sample in the integrating sphere, respectively, and L S is the luminescence emission spectrum of the sample in the integrating sphere.…”

Li6Sr(La1−xEux)2Sb2O12(0<x≤1.0) solid-solution red phosphors for white light-emitting diodes

“…QE is an important factor for a phosphor, which is defined as the ratio between the number of emitted photons (I em ) and the number of absorbed photons (I abs ), and can be calculated based on the following Eq.2 [29][30][31]: where L S , E R , and E S are representing the intensity of luminescence emission, the excitation light without and with the sample in the integrating sphere, respectively. Accordingly, the QE value of Li 6 SrLaEuSb 2 O 12 is determined to be 42.46% under 393 nm excitation (Fig.…”

Review—Phosphor Plates for High-Power LED Applications: Challenges and Opportunities toward Perfect Lighting

“…These results indicated the possibility of color converting materials for full-spectrum white lighting. Zhang et al 43 reported Fig. 3c illustrates the schematic and actual fabrication process of GPPbased wLEDs based on the UV chip-on-board (COB) configuration.…”

“…3c illustrates the schematic and actual fabrication process of GPPbased wLEDs based on the UV chip-on-board (COB) configuration. 43 Zhang et al 44 reported an Eu 2+ -doped silicate SLSAKP GPP, which had a tunable emission band. Gao et al 45 used Al powder to reduce Eu 3+ to Eu 2+ in a SiO 2 -Al 2 O 3 -Na 2 CO 3 -YF 3 -NaF glass matrix.…”