A wled lighting device and a method of manufacturing the same

Abstract

The application discloses a WLED lighting device and a preparation method thereof, and belongs to the technical field of rare earth luminescent materials. The problems of poor thermal stability of traditional organic packaging materials under high power, high preparation temperature of existing inorganic fluorescent glass, easy damage of fluorescent powder, uneven dispersion of fluorescent powder leading to blue light leakage, and difficult color temperature control are solved. The lighting device comprises a blue light LED chip and a Ce:YAG fluorescent glass. The fluorescent glass comprises a glass matrix and Y3Al5O 12 :Ce fluorescent powder. The glass matrix comprises 45-55mol% of SiO2, 15-25mol% of Al2O3, 1-10mol% of NaF, 1-10mol% of Na2O, 2-12mol% of MgO, 3-13mol% of CaO, and 1-10mol% of K2O in terms of molar percentage. The WLED lighting device has the advantages of small energy consumption, no need of complex equipment, loose and cheap material selection, and can be widely applied in the fields of lighting, display, optical devices and the like.

Description

Technical Field

[0001] This invention relates to the field of rare earth luminescent materials technology, and in particular to a WLED lighting device and its preparation method. Background Technology

[0002] White light-emitting diodes (WLEDs), as a new type of solid-state light source, have been widely used in indicator lighting, backlighting displays, automotive headlights, and general lighting due to their significant advantages such as long lifespan, small size, energy saving, environmental friendliness, and zero pollution. They are gradually replacing traditional incandescent and fluorescent lamps. Currently, mainstream commercial WLED devices typically use a blue InGaN chip to excite yellow Ce:YAG phosphor to achieve white light emission, and then use organic resin or silicone to encapsulate and integrate the phosphor with the chip. However, with the continuous increase in lighting power and brightness, this traditional packaging structure has revealed significant defects under high-power operating conditions: the organic packaging material has low thermal conductivity, making it difficult to effectively conduct the heat generated by the chip, leading to an increase in the device junction temperature; at the same time, organic materials are prone to aging, yellowing, and even cracking under high temperature and strong blue light irradiation, resulting in light output attenuation, color coordinate drift, and decreased luminous efficiency, which seriously restricts the long-term reliability and lifespan of WLED devices in high-power lighting, automotive headlights, and other fields.

[0003] To address these issues, researchers are dedicated to developing novel inorganic color conversion materials to replace organic encapsulation, such as phosphor-in-glass (PiG) and phosphor glass ceramics (GCs). These materials can be directly integrated with blue LED chips as color conversion layers to form fully inorganically encapsulated WLED devices, potentially fundamentally improving the device's heat dissipation performance and thermal stability. However, applying phosphor glass to practical WLED devices still faces a series of key technical challenges: First, the preparation of phosphor glass typically requires a high-temperature sintering process. If the sintering temperature is too high, it can easily erode the crystal structure of the YAG:Ce phosphor, damaging the luminescent centers and leading to a decrease in the device's internal and external quantum efficiencies. Furthermore, internal stress is easily generated during preparation or operation, leading to material cracking or interface delamination, affecting the device's mechanical reliability. Secondly, if the phosphor is unevenly dispersed in the glass matrix or has excessively high local concentrations, it can cause insufficient blue light absorption, uneven color space distribution, and blue light leakage, thus affecting the final WLED device's luminous efficiency, color rendering index, and color temperature consistency. In addition, optimizing material composition and processes to achieve tunable color temperature of devices within a wide range (such as 3000K-6000K) while ensuring good thermal stability is also a key requirement in practical applications.

[0004] Therefore, there is an urgent need to develop a WLED device that can be well matched with blue LED chips, has a gentle manufacturing process (avoiding damage to phosphors), and combines high luminous efficiency, excellent thermal stability, and wide color temperature tunability. Summary of the Invention

[0005] In view of the above, the present invention aims to provide a WLED lighting device and its preparation method to at least solve one of the problems existing in the prior art: (1) the quantum efficiency of traditional fluorescent glass is low and the stability is poor; (2) in traditional fluorescent glass, the glass matrix is ​​easy to erode the phosphor, resulting in low color rendering index and luminous efficiency of the prepared WLED device.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] The first aspect of this invention provides a WLED lighting device, comprising a blue LED chip and Ce:YAG fluorescent glass, wherein the fluorescent glass comprises a glass matrix and Y3Al5O 12 Ce phosphor; The glass matrix comprises, by molar percentage: 45-55 mol% SiO2, 15-25 mol% Al2O3, 1-10 mol% NaF, 1-10 mol% Na2O, 2-12 mol% MgO, 3-13 mol% CaO, and 1-10 mol% K2O.

[0008] Furthermore, the Y3Al5O 12 The mass of Ce phosphor accounts for 10-60 wt% of the total mass of the fluorescent glass.

[0009] Furthermore, the device also includes a heat dissipation substrate, and the fluorescent glass is fixed to the heat dissipation substrate by a thermally conductive adhesive layer and is located on the light emission path of the blue LED chip.

[0010] Furthermore, the blue LED chip has an emission wavelength of 440nm to 460nm.

[0011] Furthermore, the white light emitted by the WLED lighting device has a color temperature of 3000K to 6000K and a luminous efficiency of not less than 110 lm / W.

[0012] Furthermore, the thickness of the fluorescent glass is 0.2-1.25 mm.

[0013] A second aspect of the present invention provides a method for manufacturing the WLED lighting device described in the first aspect, characterized in that it comprises: S1. SiO2, Al2O3, NaF, Na2O, MgO, CaO and K2O are mixed evenly and then melted to obtain a molten liquid. After cooling, glass powder is obtained. S2, mix the glass powder and Y3Al5O 12 Ce phosphor is mixed evenly and then sintered to obtain fluorescent glass; S3. Place the fluorescent glass on the light-emitting path of the blue LED chip and fix it on the heat dissipation substrate to obtain the WLED lighting device.

[0014] Furthermore, in step S1, the melting conditions include: a melting temperature of 1200~1400℃ and a melting time of 1-4h.

[0015] Further, in step S2, the sintering conditions include: heating to 600-650°C at a heating rate of 2-10°C / min, and sintering for 10-50 min.

[0016] Furthermore, using a glass matrix and Y3Al5O 12 Based on the total mass of Ce phosphor, the percentage of phosphor used is 10~60wt%.

[0017] Furthermore, the method further includes: cutting the obtained fluorescent glass into thin slices with a thickness of 0.2 mm to 1.25 mm and polishing them.

[0018] Furthermore, an optical lens is provided on the side of the fluorescent glass away from the blue LED chip. The optical lens is made of quartz glass or sapphire. A sealed cavity is formed between the optical lens and the fluorescent glass, and the cavity is filled with inert gas.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) The WLED lighting device of the present invention uses Ce:YAG fluorescent glass based on a specific NaF-silicate system as the color conversion layer. Its all-inorganic encapsulation structure completely solves the problems of high-temperature yellowing and aging cracking of traditional organic silicone. The fluorescent glass has excellent chemical stability, which can effectively inhibit the erosion of the phosphor by the glass matrix. At the same time, thanks to the introduction of fluoride ions, the sintering temperature is significantly reduced, thereby fully protecting the crystal structure and luminescent activity of commercial Ce:YAG phosphor during the preparation process. Therefore, the prepared WLED device has higher thermal conductivity and better heat dissipation performance, which can significantly reduce the LED junction temperature, inhibit the thermal quenching of phosphor, and improve the long-term reliability and service life of the device under high-power operating conditions.

[0020] (2) By synergistically controlling the phosphor doping ratio and the thickness of the fluorescent glass, this invention enables WLED devices to achieve a wide and adjustable color temperature output within the range of 3000K to 6000K, which can meet the warm white light requirements of home lighting as well as the cool white light requirements of commercial lighting. The optimized low-temperature sintering process maximizes the protection of the phosphor's luminescent performance. As shown in Example 5, the luminous efficiency of this device can reach 141.5 lm / W, and the color rendering index is 55.7, demonstrating good photoelectric performance and color temperature consistency, providing reliable technical support for diversified and high-quality solid-state lighting applications.

[0021] (3) The WLED device fabrication process involved in this invention is simple, stable and low cost. The glass powder is combined with commercially available Ce:YAG phosphor using low-temperature co-sintering technology, and a high-performance fluorescent glass sheet can be formed at 600~650℃. No complicated equipment is required, the material selection is flexible, which is conducive to large-scale production and market promotion, and has significant advantages in industrial application. Attached Figure Description

[0022] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0023] Figure 1 The XRD patterns are those of the fluorescent glass in Examples 1-6 of this invention.

[0024] Figure 2 The images show the excitation and emission spectra of the fluorescent glass in Example 5 of this invention.

[0025] Figure 3 The images show the emission spectra of fluorescent glasses with different phosphor doping amounts in Examples 1-6 of this invention.

[0026] Figure 4 The transmittance spectra of fluorescent glasses with different phosphor doping amounts in Examples 1-6 of this invention are shown.

[0027] Figure 5 The fluorescent glass of the present invention exhibits emission spectra at different sintering temperatures.

[0028] Figure 6 The emission spectra of phosphor and fluorescent glass in the fluorescent glass of Example 5 of the present invention are shown at different test temperatures.

[0029] Figure 7 This is a comparison diagram of the EQE and IQE of fluorescent glass and phosphor in Embodiment 5 of the present invention.

[0030] Figure 8 This is a fluorescence lifetime curve of the fluorescent glass and phosphor in Example 5 of the present invention.

[0031] Figure 9 The transmittance spectra of fluorescent glasses of different thicknesses prepared in this invention are shown. Detailed Implementation

[0032] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0033] Due to the inherent poor thermal reliability and easy aging problems of traditional organic encapsulation (silicone) in existing technologies, and the problems of inorganic fluorescent materials (such as existing PiG, GCs, etc.) as alternatives, there are generally problems such as low luminous efficiency, easy blue light leakage, complex preparation process, or damage (corrosion) to phosphors. The first aspect of the present invention provides a WLED lighting device, including a blue LED chip and Ce:YAG fluorescent glass, wherein the fluorescent glass includes a glass matrix and Y3Al5O 12 Ce phosphor; The glass matrix comprises, by molar percentage: 45-55 mol% SiO2, 15-25 mol% Al2O3, 1-10 mol% NaF, 1-10 mol% Na2O, 2-12 mol% MgO, 3-13 mol% CaO, and 1-10 mol% K2O.

[0034] In this invention, the above-mentioned components work synergistically to ensure the chemical stability of the fluorescent glass, effectively prevent the glass components from corroding the Ce:YAG phosphor, and improve the luminous efficiency.

[0035] Specifically, the SiO2 content of no less than 45 mol% provides a stable structural framework for the fluorescent glass and significantly enhances its overall chemical stability, effectively preventing the glass components from corroding the Ce:YAG phosphor. Al2O3, as a network intermediate, further improves the mechanical strength and chemical durability of the glass. Fluoride ions in NaF can break Si-O-Si bonds and form Si-F bonds, thereby significantly reducing the melting temperature, viscosity, and glass transition temperature of the glass. This allows subsequent processes to achieve sintering at a lower temperature of 640℃, avoiding damage to the phosphor at high temperatures. Na2O and K2O, together with NaF, act as fluxing agents, further reducing the softening point of the system. At the same time, the addition of MgO and CaO effectively suppresses the tendency of the glass to crystallize during heat treatment and further improves the chemical stability of the material. Together, they ensure the structural stability of the final composite material at high temperatures and improve the quenching temperature of the product. Specifically, the luminescence intensity retention rate at 175℃ is no less than 78%, preferably no less than 83%.

[0036] Furthermore, considering effective resistance to erosion of Ce:YAG phosphor, the SiO2 content is 45-55 mol%. If it is less than 45 mol%, the network structure of the glass matrix is ​​incomplete, leading to a sharp decrease in the chemical stability of the fluorescent glass. The glass matrix also becomes too soft and has low viscosity during subsequent sintering, causing phosphor sedimentation or glass matrix deformation, and increasing the risk of phosphor erosion. If it is greater than 55 mol%, the melting temperature, viscosity, and transition temperature of the glass matrix will increase significantly. This results in insufficient densification during sintering at lower target sintering temperatures, leading to porosity, reduced light transmittance and mechanical strength, and thus reduced luminous efficiency. For example, the SiO2 content is 45 mol%, 48 mol%, 49 mol%, 50 mol%, 52 mol%, 53 mol%, 55 mol%, or any combination of two of these values.

[0037] Considering the good compatibility with Ce:YAG phosphor and the enhancement of the glass network, the Al2O3 content is 15-25 mol%. If it is less than 15 mol%, the network structure strength of the glass matrix is ​​insufficient, leading to further deterioration of chemical stability, weakened protection of the phosphor, and increased susceptibility to phase separation in the glass matrix. If it is greater than 25 mol%, the network structure of the glass matrix will be unstable, and the viscosity of the glass will increase significantly, making subsequent melting and densification sintering at the target sintering temperature difficult. For example, the Al2O3 content is 15 mol%, 18 mol%, 19 mol%, 20 mol%, 22 mol%, 23 mol%, 25 mol%, or any combination of two of the above values.

[0038] To achieve the crucial low-temperature sintering and adjust the glass network, the NaF concentration is 1-10 mol%. If it is less than 1 mol%, its effect on breaking Si-O-Si bonds, reducing glass viscosity, and lowering the transition temperature is not significant, leading to a higher sintering temperature and failing to achieve the goal of low-temperature sintering to protect the phosphor. If it is greater than 10 mol%, the excess F... - This can make the glass network too fragile, leading to a significant decrease in chemical stability and causing excessive crystallization during sintering. Simultaneously, fluorine is easily volatilized at high temperatures, causing compositional deviation and performance instability, thus affecting fluorescence lifetime. For example, the NaF content is 1 mol%, 1.5 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 5.5 mol%, 6 mol%, 8 mol%, 10 mol%, or any combination of the above values.

[0039] To further synergistically reduce the sintering temperature, the Na₂O content is 1-10 mol%. If it is less than 1 mol%, its fluxing effect is insufficient, resulting in high glass viscosity, which is not conducive to achieving sufficient densification during sintering at the target temperature. If it is greater than 10 mol%, too many Si-O-Si bonds will be broken, severely damaging the integrity of the glass matrix network, leading to a sharp decline in chemical stability, mechanical strength, and thermal stability, seriously affecting luminescent performance. For example, the Na₂O content is 1 mol%, 1.5 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 5.5 mol%, 6 mol%, 8 mol%, 10 mol%, or any combination of the above values.

[0040] To jointly suppress crystallization and optimize high-temperature viscosity, the MgO content is 2-12 mol%, and the CaO content is 3-13 mol%. If the content is too low (MgO < 2 mol% or CaO < 3 mol%), the mixed alkaline earth effect cannot be effectively utilized to suppress the crystallization tendency of the glass matrix during heat treatment, and the chemical stability of the glass matrix is ​​also poor. If the content is too high (MgO > 12 mol% or CaO > 13 mol%), the glass network will be excessively broken, reducing its chemical durability and making it difficult to obtain uniform and transparent fluorescent glass. For example, the MgO content is 12 mol%, 3 mol%, 4 mol%, 5 mol%, 5.5 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, or any two of the above values.

[0041] To further optimize performance by utilizing the mixed alkali effect of MgO and CaO, the K2O content is 1~10 mol%. If it is less than 1 mol%, it cannot produce an effective synergistic effect with Na2O, and its additional contribution to inhibiting crystallization and reducing melting temperature is not significant. If it is greater than 10 mol%, excessive K2O will introduce too many network bond breaks due to its large ionic radius. Similar to excessive Na2O, it will severely weaken the glass network structure and adversely affect thermal and chemical stability. For example, the contents of MgO and CaO are each independently 1 mol%, 1.5 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 5.5 mol%, 6 mol%, 8 mol%, 10 mol%, and any two of the above values.

[0042] In summary, the specific composition system described above can ultimately achieve a lower sintering temperature, avoiding damage to the Ce:YAG phosphor structure, while obtaining good chemical stability and protecting the phosphor interface from corrosion, making it suitable for high-power WLED lighting devices.

[0043] In this invention, it is understood that the Ce:YAG phosphor used is commercially available Y3Al5O. 12 Ce, 450nm excitation, 555nm emission.

[0044] According to some embodiments of the present invention, the phosphor in the fluorescent glass has a mass percentage of 10-60 wt%.

[0045] In this invention, when the mass percentage of phosphor is less than 10 wt%, the phosphor's absorption of blue light is insufficient, leading to a higher color temperature and lower luminous efficiency in the device. When the content continues to increase to above 60 wt%, the excessively dense phosphor particles trigger a significant concentration quenching effect, while simultaneously exacerbating light scattering, which in turn leads to a decrease in internal quantum efficiency and luminous intensity. Exemplarily, in the fluorescent glass, the mass percentage of phosphor is 10 wt%, 15 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or any two of the above values, preferably 40-50 wt%.

[0046] According to some embodiments of the present invention, the device includes a blue LED chip, a fluorescent glass, and a heat dissipation substrate, wherein the fluorescent glass is fixed to the heat dissipation substrate by a thermally conductive adhesive layer and is located in the light emission path of the blue LED chip.

[0047] According to some embodiments of the present invention, the emission wavelength of the blue LED chip is 440nm to 460nm.

[0048] In a preferred embodiment of the WLED lighting device, an optical lens is provided on the side of the fluorescent glass away from the blue LED chip. The optical lens is made of high-transmittance, high-temperature-resistant quartz glass or sapphire. A sealed cavity is formed between the optical lens and the fluorescent glass through a sealing structure, and this cavity is filled with an inert gas (such as nitrogen or argon). This structural design not only helps to shape the emitted light, improve the uniformity of the light field and the light extraction efficiency, but also effectively isolates oxygen and moisture, preventing oxidation or moisture absorption of the fluorescent glass and interface materials during long-term operation. This further enhances the device's heat dissipation capacity and long-term environmental stability, making it more suitable for high-power, high-reliability lighting applications.

[0049] According to some embodiments of the present invention, the thickness of the fluorescent glass is 0.2-1.25 mm. A thickness less than 0.2 mm will result in insufficient blue light absorption and blue light leakage, while a thickness greater than 1.25 mm will increase internal light scattering and absorption loss, reducing light extraction efficiency. Polishing treatment can significantly reduce Fresnel reflection loss and light scattering caused by roughness when light enters and exits the sample surface.

[0050] A second aspect of the present invention provides a method for manufacturing the WLED lighting device described in the first aspect, comprising: S1. SiO2, Al2O3, NaF, Na2O, MgO, CaO and K2O are mixed evenly and then melted to obtain a molten liquid. After cooling, glass powder is obtained. S2, mix the glass powder and Y3Al5O 12 Ce phosphor is mixed evenly and then sintered to obtain fluorescent glass; S3. Place the fluorescent glass on the light-emitting path of the blue LED chip and fix it on the heat dissipation substrate to obtain the WLED lighting device.

[0051] In this invention, the above preparation method is simple, directly mixing the glass powder obtained in S1 with commercially available Y3Al5O 12 Ce phosphor is mixed and sintered to form Ce:YAG fluorescent glass. The fluorescent glass is then placed on the light-emitting path of the blue LED chip and fixed on a heat dissipation substrate to obtain the WLED lighting device. The preparation process is simple, the process is stable and controllable, and the cost is low, giving it a cost advantage.

[0052] In this invention, it is understood that the amount of the raw materials used is: 45-55 mol% SiO2, 15-25 mol% Al2O3, 1-10 mol% NaF, 1-10 mol% Na2O, 2-12 mol% MgO, 3-13 mol% CaO and 1-10 mol% K2O.

[0053] In this invention, it is understood that the cooling can be performed in water.

[0054] According to some embodiments of the present invention, in step S1, the melting conditions include: a melting temperature of 1200~1400℃ and a melting time of 1~4h.

[0055] In this invention, the melting temperature within the aforementioned range ensures that all oxide raw materials can be completely melted and fully homogenized in the liquid phase, thereby forming a glass melt with uniform chemical composition. The holding time of 1 to 4 hours provides kinetic assurance for this homogenization process, while allowing sufficient time for gases in the melt to escape, significantly reducing internal bubble defects. The resulting glass matrix exhibits excellent optical homogeneity and stable chemical properties.

[0056] According to some embodiments of the present invention, in step S2, the sintering conditions include: heating to 600-650°C at a heating rate of 2-10°C / min, and sintering for 10-50 min.

[0057] In this invention, the aforementioned heating rate allows for the slow decomposition of organic impurities and evaporation of moisture in the glass powder, reducing the risk of sample cracking due to thermal stress. Strictly controlling the sintering temperature within the range of 600-650℃, far below the degradation temperature of Ce:YAG phosphor, and maintaining this temperature for 10-50 minutes, allows the glass powder to reach a viscous flow state, fully encapsulating the phosphor particles and achieving densification. Simultaneously, it maximally suppresses the thermal erosion of the phosphor lattice and interfacial reactions by the glass components, thereby improving internal quantum efficiency.

[0058] According to some embodiments of the present invention, a glass matrix and Y3Al5O are used. 12 Based on the total mass of Ce phosphor, the percentage of phosphor used is 10~60wt%.

[0059] In this invention, when the content is below 10wt%, insufficient blue light absorption leads to excessively high device color temperature and low luminous efficiency; if the content exceeds 60wt%, the phosphor particles are too close together, which will trigger a concentration quenching effect and exacerbate light scattering, thus reducing luminous efficiency. For example, the percentage of phosphor used is 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, or any two of the above values, preferably 40-50wt%.

[0060] According to some embodiments of the present invention, in order to facilitate subsequent low-temperature densification sintering, the method further includes: grinding the glass powder after the molten liquid has been cooled to 10-15 micrometers.

[0061] According to some embodiments of the present invention, the method further includes: cutting the obtained Ce:YAG fluorescent glass into thin slices with a thickness of 0.2 mm to 1.25 mm and polishing them.

[0062] In this invention, a diamond wire cutter can be used to cut fluorescent glass.

[0063] In this invention, a fluorescent glass thickness of less than 0.2 mm leads to insufficient blue light absorption and blue light leakage, while a thickness greater than 1.25 mm increases internal light scattering and absorption losses, reducing light extraction efficiency. Polishing significantly reduces Fresnel reflection losses and light scattering caused by roughness when light enters and exits the sample surface.

[0064] After precise thickness control and polishing, the fluorescent glass sheet can achieve higher light extraction efficiency and better heat dissipation performance when encapsulated into WLED devices, thereby ensuring that the final WLED device has a high color rendering index, high luminous efficiency and stable light and color output.

[0065] For example, the thickness of the fluorescent glass is 0.2 mm, 0.25 mm, 0.3 mm, 0.5 mm, 0.75 mm, 0.8 mm, 1 mm and 1.25 mm, or any two of the above values, preferably 0.4 to 0.6 mm.

[0066] According to some embodiments of the present invention, an optical lens is provided on the side of the fluorescent glass away from the blue LED chip. The optical lens is made of quartz glass or sapphire. A sealed cavity is formed between the optical lens and the fluorescent glass, and the cavity is filled with an inert gas.

[0067] In this invention, the emitted white light is first shaped by an optical lens to improve the uniformity of the light field and the extraction efficiency. Secondly, quartz glass or sapphire with high light transmittance, high temperature resistance and good thermal conductivity is selected so that it can withstand high power irradiation and heat load for a long time and avoid aging and yellowing of ordinary materials. The inert gas (such as nitrogen or argon) filled in the sealed cavity can effectively isolate oxygen and water vapor, prevent the fluorescent glass and interface materials from oxidizing or getting damp, and at the same time enhance heat dissipation and stabilize the optical path environment.

[0068] The above-mentioned structure not only helps to shape the emitted light, improve the uniformity of the light field and the light extraction efficiency, but also effectively isolates oxygen and water vapor, preventing the fluorescent glass and interface materials from oxidizing or becoming damp during long-term operation, further enhancing the heat dissipation capacity and long-term environmental stability of the device, making it more suitable for high-power and high-reliability lighting applications.

[0069] The WLED lighting device described in this invention can serve as a high-power, high-brightness, and long-life white LED lighting device, such as automotive headlights, special lighting, and high-end general lighting. It can withstand higher operating currents and chip temperatures, exhibiting longer fluorescence decay lifetime and stronger resistance to thermal quenching, thus significantly promoting the development of solid-state lighting technology towards higher performance.

[0070] The advantages of the method of the present invention will be illustrated below through examples.

[0071] In the following examples, the crystal structure of the phosphor was tested using an X'Pert PRO X-ray diffractometer.

[0072] Excitation and emission spectra were measured using an Edinburgh (FL1000) fluorescence spectrometer.

[0073] The internal / external quantum efficiency of luminescence was measured using an Edinburgh (FL1000) fluorescence spectrometer.

[0074] Color rendering index and color temperature were tested using the Far East HAAS-2000.

[0075] Luminous efficiency was tested using the Yuanfang HAAS-2000.

[0076] Fluorescence lifetime was measured using an Edinburgh (FL1000) fluorescence spectrometer.

[0077] Luminous intensity retention rate = luminous intensity measured at 175℃ / luminous intensity measured at room temperature × 100%.

[0078] Example 1 S1. Weigh out 50 mol% SiO2, 20 mol% Al2O3, 5 mol% NaF, 5 mol% Na2O, 7 mol% MgO, 8 mol% CaO, and 5 mol% K2O according to stoichiometric coefficients. Then, place the above raw materials in an agate mortar and grind them thoroughly. Pour the ground mixed powder into an alumina crucible and sinter it in a high-temperature furnace at 1300℃ for 2 hours to obtain a molten liquid. Pour it into water and cool it to obtain a precursor glass block. Finally, grind the glass precursor into 13 micrometer glass powder. S2. The glass powder and Ce:YAG phosphor are mixed evenly to obtain a mixture, wherein the content of Ce:YAG phosphor accounts for 10wt% of the mixture. The mixture is placed in a muffle furnace at 640℃ for sintering. The sintering process is as follows: the initial temperature is room temperature, the temperature is increased to the sintering temperature at a heating rate of 5℃ / min, and then held at this temperature for 30min. Then the temperature is lowered with the furnace and naturally cooled to obtain a large piece of YAG fluorescent glass. The obtained large piece of YAG fluorescent glass is then cut to a thickness of 0.5mm using a diamond wire cutter and polished to obtain the sample YAG fluorescent glass. S3. A copper-clad aluminum substrate is selected as the heat dissipation substrate. After printing an insulating layer on its surface, a blue InGaN LED chip with an emission wavelength of 450 nm is fixed to the designated pad position using die bond adhesive. Gold wire bonding is then completed to form an electrical connection. High thermal conductivity silica sol is used as an adhesive layer and is uniformly coated on one side of the fluorescent glass sheet. It is then precisely attached to the top of the LED chip, ensuring that the fluorescent glass completely covers the chip's light-emitting surface and is pressed parallel to the substrate. After curing, a quartz glass optical lens is assembled on the outside of the light-emitting surface of the fluorescent glass. The lens edge is sealed and welded at 450°C using low-temperature glass powder to form a sealed cavity. High-purity nitrogen is then filled into the cavity as an inert protective atmosphere to obtain the WLED device.

[0079] Examples 2-6 The method is the same as in Example 1, except that the content of Ce:YAG phosphor in Examples 2-6 is 20wt%, 30wt%, 40wt%, 50wt%, and 60wt% of the mixture, respectively.

[0080] Example 7 The method is the same as in Example 1, except that the molar fraction of SiO2 is 45 mol.

[0081] Example 8 The method is the same as in Example 1, except that the amount of NaF used is 1 mol.

[0082] Example 9 The method is the same as in Example 1, except that the amount of NaF used is 3 mol.

[0083] Example 10 The method is the same as in Example 1, except that the amount of MgO is 2 mol% and the amount of CaO is 13 mol%.

[0084] Examples 11-12 The method is the same as in Example 4, except that the fluorescent glass is cut into thin slices of 0.2 mm and 1 mm, respectively.

[0085] Comparative Example 1 The method is the same as in Example 1, except that the SiO2 content is 40 mol.

[0086] Comparative Example 2 The method is the same as in Example 1, except that the amount of NaF used is 12 mol.

[0087] Comparative Example 3 The method is the same as in Example 1, except that it does not contain Na2O.

[0088] Comparative Example 4 The method is the same as in Example 1, except that it does not contain MgO and CaO.

[0089] Comparative Example 5 The method is the same as in Example 1, except that the content of Ce:YAG phosphor accounts for 5 wt% of the mixture.

[0090] Test case The internal and external quantum efficiency, thermal quenching performance (luminescence intensity retention rate), and fluorescence lifetime of the fluorescent glasses prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0091] Further, the fluorescent glass was fabricated into a WLED lighting device. Specifically, the fluorescent glass obtained in the examples and comparative examples was polished on both sides and then tightly bonded to the light-emitting surface of a 450 nm blue LED chip (InGaN chip) using an inorganic encapsulating agent (silica sol). Subsequently, electrical connections were completed through wire bonding, and the device was assembled into a lamp holder with a high thermal conductivity metal or ceramic substrate. Finally, a standard packaging process was performed to obtain the WLED lighting device. The color temperature, color rendering index, and luminous efficiency of the WLED lighting device were tested under the excitation of a 450 nm blue LED chip, and the results are shown in Table 2.

[0092] Table 1

[0093] Table 2

[0094] Figure 1 By comparing with the standard Ce:YAG diffraction peaks, it can be confirmed that in the devices of Examples 1-6, the phosphor maintains a complete crystal structure in the glass matrix without significant phase transition or decomposition, indicating that the low-temperature sintering process effectively protects the phosphor lattice.

[0095] Figure 2 The figure shows the emission spectrum of the fluorescent glass in the device prepared in Example 5 under a specific wavelength excitation. It can be seen from the figure that the fluorescent glass can be effectively excited by blue light and emits yellow light, which is consistent with the light emission characteristics of YAG:Ce and is suitable for blue LED excitation.

[0096] Figure 3 The emission spectra of fluorescent glasses with different phosphor doping amounts in Examples 1-6 show that as the phosphor content increases, the emission intensity of yellow light first increases and then decreases, indicating that the optimal doping range (e.g., 40~50wt%) is not ideal. Excessive doping can lead to quenching.

[0097] Figure 4 The transmittance spectra of fluorescent glasses with different phosphor doping amounts in Examples 1-6 show the transmittance curves of fluorescent glasses with different phosphor contents. The higher the phosphor content, the lower the transmittance in the blue light region, indicating that more blue light is absorbed and converted into yellow light. However, too high a content will affect the overall transmittance and uniformity.

[0098] Figure 5 The transmittance spectra of fluorescent glass at different sintering temperatures (Example 5 uses a sintering temperature of 640°C) are shown. The transmittance of fluorescent glass prepared at different sintering temperatures (with constant glass matrix and phosphor doping amounts) was compared. This indicates that sintering temperatures that are too low or too high will affect the density and transmittance of the glass, and 600~650°C is the optimal sintering temperature range.

[0099] Figure 6 The emission spectra of the phosphor and the fluorescent glass in Example 5 at different test temperatures were shown, comparing the luminescence stability of the original phosphor and the fluorescent glass during the heating process. This indicates that the fluorescent glass maintains its luminescence intensity better at high temperatures, demonstrating that the glass matrix protects the phosphor and improves its thermal stability.

[0100] Figure 7 The graphs show a comparison of the EQE and IQE of fluorescent glass and phosphor, comparing the quantum efficiency of the fluorescent glass and the original phosphor. The results indicate that the IQE of the fluorescent glass is higher than that of the phosphor, suggesting that the glass matrix does not significantly impair the luminescence performance of the phosphor, and the higher EQE indicates superior light extraction efficiency.

[0101] Figure 8 The graph shows the fluorescence lifetime curves of the fluorescent glass and phosphor in Example 5. It can be seen from the graph that the fluorescent glass in Example 5 has a longer fluorescence lifetime (above 60 ns), indicating that the material has good luminescence stability and a low quenching tendency.

[0102] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A WLED lighting device, characterized in that, It includes a blue LED chip and Ce:YAG fluorescent glass, wherein the fluorescent glass comprises a glass matrix and Y3Al5O 12 Ce phosphor; The glass matrix comprises, by molar percentage: 45-55 mol% SiO2, 15-25 mol% Al2O3, 1-10 mol% NaF, 1-10 mol% Na2O, 2-12 mol% MgO, 3-13 mol% CaO, and 1-10 mol% K2O.

2. The WLED lighting device according to claim 1, characterized in that, The Y3Al5O 12 The mass of Ce phosphor accounts for 10-60 wt% of the total mass of the fluorescent glass.

3. The WLED lighting device according to claim 1, characterized in that, The device also includes a heat dissipation substrate, and the fluorescent glass is fixed to the heat dissipation substrate by a thermally conductive adhesive layer and is located on the light emission path of the blue LED chip.

4. The WLED lighting device according to claim 3, characterized in that, The blue LED chip emits light at a wavelength of 440nm to 460nm. And / or, the white light emitted by the WLED lighting device has a color temperature of 3000K to 6000K and a luminous efficiency of not less than 110 lm / W.

5. The WLED lighting device according to any one of claims 1-4, characterized in that, The thickness of the fluorescent glass is 0.2-1.25 mm.

6. A method for preparing a WLED lighting device according to any one of claims 1-5, characterized in that, include: S1. SiO2, Al2O3, NaF, Na2O, MgO, CaO and K2O are mixed evenly and then melted to obtain a molten liquid. After cooling, glass powder is obtained. S2, mix the glass powder and Y3Al5O 12 Ce phosphor is mixed evenly and then sintered to obtain fluorescent glass; S3. Place the fluorescent glass on the light-emitting path of the blue LED chip and fix it on the heat dissipation substrate to obtain the WLED lighting device.

7. The preparation method according to claim 6, characterized in that, In step S1, the melting conditions include: a melting temperature of 1200~1400℃ and a melting time of 1-4h; And / or, in step S2, the sintering conditions include: heating to 600-650°C at a heating rate of 2-10°C / min, and sintering for 10-50 min.

8. The preparation method according to claim 6, characterized in that, With glass matrix and Y3Al5O 12 Based on the total mass of Ce phosphor, the percentage of phosphor used is 10~60wt%.

9. The preparation method according to claim 6, characterized in that, The method further includes: cutting the obtained fluorescent glass into thin slices with a thickness of 0.2 mm to 1.25 mm and then polishing them.

10. The preparation method according to any one of claims 6-9, characterized in that, An optical lens is provided on the side of the fluorescent glass away from the blue LED chip. The optical lens is made of quartz glass or sapphire. A sealed cavity is formed between the optical lens and the fluorescent glass, and the cavity is filled with inert gas.

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