Mapping the glass forming region and making their phosphor‐in‐glass for application in W‐LEDs packaging

Abstract

The application of phosphor‐in‐glass (PiG) packaging material in white‐light emitting diodes (W‐LEDs) can improve the thermal stability and luminous efficacy of LED devices. In this work, a low melting point glass of TeO2–ZnO–Na2O–B2O3 (TZNB) was selected as glass matrix, and mixed with YAG: Ce3+ phosphor powders to obtain phosphor‐in‐tellurite glass (PiTG). In a significant advance, we mapped the glass forming region of TZNB for the first time. This high refractive index glass matrix with low melting temperature was achieved by optimizing the glass composition. The refractive index increased regularly from 1.61 to 2.03, when the dosage of TeO2 increased from 15 to 75 mol%. Through Monte Carlo simulations and numerical calculations, the optimal structure of gradient refractive index (GRIN) was designed, which is consisted of TZNB‐1 (n = 2.03), TZNB‐4 (n = 1.79), TZNB‐6 (n = 1.66), and glass substrate (n = 1.52). The PiTG with GRIN coating was fabricated by screen printing and low‐temperature sintering, and the optimized sintering temperature is 575°C. Compared with the single refractive index (SRIN) coating, the luminous efficacy of PiTG with GRIN coating was enhanced from 9.51% to 23.12%. Therefore, this work provides a significant application in high‐power W‐LEDs.

Composition and luminescence properties of highly robust green-emitting LuAG:Ce/Al 2O 3 composite phosphor ceramics for high-power solid-state lighting

“…However, they are subject to yellowing and aging problems at high excitation power density, resulting in reduced luminous efficacy and color drift. To solve the problem, phosphor-in-glass (PiG) obtained by incorporating YAG:Ce powders into glass has been developed as a new color converter with high thermal conductivity (~1.17 W•m −1 •K −1 ) [13][14][15][16][17]. As an alternative, YAG:Ce ceramics are gaining increasing interest for their high thermal conductivity (5-8 W•m −1 •K −1 ) and homogeneity [18][19][20].…”

Porous Ce:YAG ceramics with controllable microstructure for high‐brightness laser lighting

“…As a new type of lighting technology, solid‐state lighting devices are gradually replacing traditional light sources due to their advantages of compact structure, long service life, energy‐saving, and high brightness 1 . Solid‐state lighting devices based on white‐light‐emitting diodes are mainly packaged by using phosphor‐in‐silicone dispensing technology, which has poor heat dissipation and easily causes aging and yellowing problems 2,3 . Moreover, the inherent “efficiency droop” problem of LED chips cannot be avoided.…”

“…1 Solid-state lighting devices based on white-light-emitting diodes are mainly packaged by using phosphor-in-silicone dispensing technology, which has poor heat dissipation and easily causes aging and yellowing problems. 2,3 Moreover, the inherent "efficiency droop" problem of LED chips cannot be avoided. On the other hand, blue laser diodes (LDs) can maintain a stable wall plug efficiency at an ultrahigh current density of 28 kA/cm 2 and have a smaller emitting area as well as lower beam divergence, which is appreciated for luminaire designs with small size.…”

Glass forming region and bonding mechanism of low‐melting V2O5–TeO2–Bi2O3 glass applied in vacuum glazing sealing

“…Table 1 manifests the coefficients of thermal expansion (CTE), transition temperatures (T g ) and sealing temperatures (T s ) of several kinds of lead-free low-melting glass. [23][24][25][26][27][28][29][30][31][32][33][34][35] Novel bonding technique is critical to establish firm bonding between sealing material and glass substrates. Anodicbonding is a well-established technique to produce hermetic sealing between silicon/metals and glass materials, which is widely used for integration in Micro/Nano-Electromechanical Systems.…”

“…Researchers have been concentrating on substituting PbO with Bi 2 O 3 , P 2 O 5 , V 2 O 5 , SnO, and other oxides. Table 1 manifests the coefficients of thermal expansion (CTE), transition temperatures ( T g ) and sealing temperatures ( T s ) of several kinds of lead‐free low‐melting glass 23–35 …”