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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]

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]