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This paper systematically investigates the luminous properties and thermal reliability of phosphor-in-glass (PiG)-based white light-emitting diodes (WLEDs). The PiG was prepared by introducing yellow YAG:Ce3+ phosphor embedded with borosilicate glass through screen-printing and low-temperature sintering. The effects of sintering temperature, phosphor content, and phosphor layer thickness were studied, and then the optimized PiG was achieved. This PiG-based WLED module yields a luminous efficacy (LE) of 114 lm/W, a correlated color temperature of 5524 K, and a color rendering index of 69 at the driving current of 700 mA. Furthermore, after thermal aging test at 200 °C for 500 h, the photoluminescence intensity of PiG is only reduced by 4.3%, which is much lower than the conventional phosphor-in-silicone (PiS) of 26.2%. The LE losses of PiG-based and PiS-based WLED modules are 4.2% and 12.1% after thermal aging of 1000 h at 100 °C, respectively. The aging results show that the proposed PiG exhibits superior thermal stability characteristic, which promises the excellent thermal reliability for PiG-based WLEDs. [ABSTRACT FROM AUTHOR]

In order to improve the luminous properties of high-power white light-emitting diodes (WLEDs), we proposed a facile preparation of patterned phosphor-in-glass (PiG) in which yellow Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ) and red CaAlSiN 3 :Eu 2+ (CASN:Eu 2+ ) phosphor parts are separated. The patterned PiGs with sector piece and concentric ring phosphor geometries were prepared by screen-printing and low-temperature sintering. Experimental results indicated that LED modules packaged by the patterned PiGs yield high luminous efficacy and excellent color quality owing to the reducing reabsorption of yellow emission by red phosphor. In addition, the angular color uniformity (ACU) of LED modules with the ring patterned PiGs are better than those of LED modules with the piece patterned PiGs. It is also discovered that the luminous efficacy and corresponding correlated color temperature (CCT) of LED module packaged by the piece/ring patterned PiG are decreased with the increasing of piece/ring number. [ABSTRACT FROM AUTHOR]

The coating of phosphor-in-glass with high refractive index was successfully fabricated for enhanced light extraction efficiency of white LEDs through a multilayer screen-printing and low-temperature sintering procedure. The effects of sintering temperature on the BO-SiO-ZnO glass coating and YAG:Ce phosphor concentration on the phosphor-in-glass coating were investigated. The BO-SiO-ZnO glass matrix possesses low glass transition temperature and appropriate thermal expansion coefficient. With the addition of LaO and WO, high refractive index of 1.82 at 460 nm is acquired. The amorphous glass coating, sintered at 600 °C, yields an optimized transmittance of 50%. Furthermore, negligible thermal degradation is observed in the phosphor-in-glass coating, and the emission peak under the 460-nm excitation is at ~540 nm. When increasing the concentration of phosphor, luminous efficacy and correlated color temperature are both improved, but color rendering index is deteriorated. As the refractive index increases, the light extraction efficiency of white LEDs is enhanced due to the reason that the match of refractive index between the glass matrix and the phosphor decreases the total internal reflection at the interface. [ABSTRACT FROM AUTHOR]

The phosphor-in-glass (PiG) coating was fabricated via multilayer screen-printing and low-temperature sintering. The PiG coating consisted of Eu 2 O 3 -doped P 2 O 5 -ZnO-B 2 O 3 (PZB) glass, Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) yellow phosphor, and CaAlSiN 3 :Eu 2+ (CASN:Eu) red phosphor. Eu 2 O 3 and CASN:Eu were used to provide red emission for tunable chromaticity of white light-emitting diodes (LEDs), and surprisingly, the luminous efficacy was also enhanced. The impact of the variation in the B 2 O 3 content on the PZB glass and the effect of Eu 2 O 3 , YAG: Ce, and CASN:Eu on the luminescent properties of the PiG coating were investigated. The glass matrix with 8 mol% B 2 O 3 showed the lowest transition temperature and a suitable coefficient of thermal expansion. The spectra showed that the coating can be excited by blue light and produce yellow light and red light. The spatial distribution of the PiG coating was inspected by scanning electron microscopy, and it was observed that only a low erosion of phosphor by the glass matrix occurred. Furthermore, the white LEDs devices were constructed with the PiG coating on the blue LED chips. This method showed a decreased correlated colour temperature of 5137, a increased colour rendering index of 82.8 and an improvement in the luminous efficacy. The PiG coating for tunable chromaticity and enhanced luminous efficacy of white LEDs shows potential for application. [ABSTRACT FROM AUTHOR]

A multilayer gradient refractive index (GRIN) phosphor in glass (PiG) on Boron-silicate glass substrate is introduced to improve the luminous efficiency of white light-emitting diode (WLED) packages. The multilayer PiG coating employing gradual altering refractive index (RI) P 2 O 5 -ZnO-B 2 O 3 -BaO (PZBB) glass is fabricated using multilayer screen-printing and low-temperature sintering. Properties of PZBB glass, surface topography, transmittance, and luminous efficiency of phosphor in PZBB glass with GRIN are investigated. The results demonstrated that when barium oxide is added from 0 to 20 mol%, coefficient of thermal expansion (CTE), glass transformation temperature (Tg), and RI increase from 84.00 to 97.91 ∗ 10 − 7 /K, 390.3 to 445.2 °C, and 1.42 to 1.58, respectively. PZBB glass with RI values of 1.51, 1.54 and 1.58 is synthesized in PiG to achieve GRIN. After sintering at 600 °C for 30 min, phosphor in PZBB glass with GRIN still retains a perfect surface, which indicates its CTE of interfacing layers are matched. Transmittance of phosphor in PZBB glass with GRIN increases when adding GRIN layers, and the luminous efficiency is enhanced over 28.87%, compared to that of PiG with conventional structure. [ABSTRACT FROM AUTHOR]