Gallium germanate near-infrared luminescent material, preparation method and LED light-emitting device

Abstract

The application discloses a gallium germanate near-infrared luminescent material, a preparation method and an LED light-emitting device. The chemical general formula of the luminescent material is Ca3Sn2Ga2GeO 12 :xFe 3+ (0

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a gallium germanate near-infrared luminescent material, its preparation method, and an LED luminescent device. Background Technology

[0002] In recent years, near-infrared light sources, characterized by good penetration, non-destructive properties, long lifespan, and energy efficiency, have been widely used in night vision, food analysis, non-destructive testing, and biomedicine. In particular, with the increasing prevalence of smart devices such as smartphones, smartwatches, and fitness trackers, there are increasingly higher demands for small, portable near-infrared light sources. However, traditional solid-state light sources (such as halogen tungsten lamps) suffer from drawbacks such as low luminous efficiency, high energy consumption, and bulky size, making them unsuitable for portable near-infrared devices. Therefore, near-infrared fluorescent conversion LEDs (NIRpc-LEDs) have recently attracted widespread attention due to their small size, high efficiency, and adjustable emission. However, developing efficient broadband near-infrared emitting materials remains one of the key obstacles in the development of NIRpc-LEDs.

[0003] Currently reported broadband near-infrared emitting phosphors are mainly based on transition metal ions (Cr). 3+ This is because when it is located in a weakly octahedral coordination crystal field, it can typically produce broadband emission in the 650-1200 nm range. Furthermore, due to spin-allowed... 4 A 2g → 4 T 1g This transition allows for effective absorption in the blue light band, which is a perfect match for commercial blue LED chips. However, Cr... 3+ The luminescence of this light is strongly dependent on the coordination environment of the matrix lattice, requiring a weak crystal field with six coordination units. Otherwise, it is attributed to... 2 E g → 4 Narrowband launches with the A2 transition will dominate. Furthermore, Cr... 3+ Under oxidative synthesis conditions, it is prone to react with Cr. 4+ and Cr 6+ The coexistence of chromium-doped materials not only limits their near-infrared luminescence efficiency but also increases their biotoxicity, making them unsuitable for applications with high safety requirements. Therefore, there is an urgent need to find a suitable chromium-doped material. 3+ Alternatives to activators are needed to accelerate research progress and application of near-infrared luminescence. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a novel Fe... 3+Activated gallium germanate near-infrared luminescent material with garnet structure, its preparation method and near-infrared LED prototype device. The luminescent material of the present invention has considerable absorption efficiency in both the near-ultraviolet and visible blue light regions. In addition, compared with the same type of Fe 3+ activated luminescence system products, it can have excellent luminescence performance within a wide doping concentration range. The broadband near-infrared light generated by it not only has a high luminescence quantum efficiency but also has excellent luminescence thermal stability performance. At the same time, it can also be pumped by a low-cost blue LED chip, thus providing an excellent alternative route other than Cr 3+ activated products. Specifically,

[0005] One of the purposes of the present invention is to provide a gallium germanate near-infrared luminescent material with garnet structure, and the chemical composition formula of the luminescent material is Ca3Sn2Ga2GeO 12 :xFe 3+ , where 0 < x ≤ 0.10. The luminescent material of the present invention uses gallium germanate with a garnet-type structure as the matrix and trivalent iron ions (Fe 3+ ) as the activator.

[0006] Another purpose of the present invention is to provide a preparation method for the above luminescent material, including the following steps:

[0007] 1) According to the stoichiometric ratio of the general formula Ca3Sn2Ga2GeO 12 :xFe 3+ (where 0 < x ≤ 0.10), accurately weigh the raw materials of calcium source, tin source, gallium source, germanium source and iron source by weight respectively, mix them to obtain a raw material mixture; grind the raw material mixture to make it fully mixed evenly;

[0008] 2) Calcinate the raw material mixture obtained in step 1) in an air atmosphere to obtain the luminescent material. The temperature of the calcination is 1400 - 1500 °C and the time is 4 - 8 hours; the obtained luminescent material can be ground into a powder form. Since the sintered body obtained by calcination usually has irregular sample particle morphology, larger particle size and uneven particle size distribution, it generally needs to be ground. The grinding time is generally 5 minutes to 2 hours, preferably 10 minutes to 1 hour, more preferably 15 minutes to 30 minutes, and then a powder-form luminescent material with regular particle morphology, smaller particle size and uniform particle size distribution can be obtained.

[0009] Preferably, the source of the raw materials mentioned in step 1) is as follows: the calcium source is one or more substances selected from elemental calcium, calcium oxide, and compounds that can be converted into calcium oxide (e.g., the calcium source is elemental calcium, the calcium source is a mixture of elemental calcium and calcium oxide, the calcium source is a mixture of two compounds that can be converted into calcium oxide, or the calcium source is a mixture of elemental calcium and one compound that can be converted into calcium oxide); the tin source is tin oxide; the gallium source is gallium oxide; the germanium source is germanium oxide; and the iron source is iron oxide, magnetite, ferrous oxide, or ferric chloride.

[0010] Preferably, the compounds that can be converted into calcium oxide include calcium chlorides, sulfides, carbonates, sulfates, phosphates, and nitrates.

[0011] Preferably, the raw material mixture further contains a fluxing additive, which is one or more of CaF2, NH4F, LiF, Li2CO3, Na2CO3, K2CO3 and H3BO3.

[0012] Preferably, the calcination in step 2) uses a heating device with a high heating rate.

[0013] Preferably, the calcination in step 2) involves placing the raw material mixture in an alumina corundum crucible for calcination.

[0014] A third objective of this invention is to provide an infrared LED light-emitting device, the device comprising an LED chip and the light-emitting material as described in claim 1, wherein the LED chip is an ultraviolet LED chip or a blue LED chip, and the light-emitting material is located on the LED chip.

[0015] Preferably, the ultraviolet LED chip is an InGaN semiconductor chip with an emission wavelength in the range of 300-340nm, and the blue LED chip is an InGaN semiconductor chip with an emission wavelength in the range of 405-415nm.

[0016] Preferably, the luminescent material is uniformly dispersed in epoxy resin, then coated or dispensed onto the LED chip, and cured by heating.

[0017] The luminescent material of this invention is a material composed of Fe 3+The newly activated near-infrared luminescent material can be excited by ultraviolet or visible blue light, possessing broad application applicability. The preparation method of the luminescent material of this invention is simple, easy to operate, and uses low-cost raw materials. It requires minimal production equipment and is pollution-free. Furthermore, it achieves ultrafast synthesis of the near-infrared luminescent material, resulting in a wide excitation and emission range. It emits high-intensity near-infrared light covering the far-infrared to near-infrared (650-1000nm) range, exhibiting high luminous quantum efficiency (>50%) and excellent luminous thermal stability (>70%@423K). The luminescent material of this invention demonstrates excellent luminescent performance and has significant application potential in night vision, non-destructive testing, food analysis, and information anti-counterfeiting. Its simple and low-cost preparation method promises substantial social and economic benefits, making it suitable for widespread industrial application. The NIR pc-LED prototype device, encapsulated with the luminescent material of this invention and ultraviolet or blue LEDs, exhibits good luminous intensity, lumen efficiency, and photoelectric conversion efficiency, and can be used in high-power near-infrared luminescent applications. Attached Figure Description

[0018] Figure 1 To prepare different Fe 3+ X-ray diffraction (XRD) pattern of near-infrared luminescent material at activation concentration;

[0019] Figure 2 The excitation and emission spectra of the near-infrared luminescent material of this invention are shown below.

[0020] Figure 3 The results show the luminescence quantum efficiency of the near-infrared luminescent material of this invention.

[0021] Figure 4 This is a graph showing the change in emission intensity of the near-infrared luminescent material of the present invention as a function of temperature;

[0022] Figure 5 The luminescence intensity of the near-infrared luminescent material prepared by introducing Na2CO3 additive in this invention has been optimized and improved.

[0023] Figure 6 This is the electroluminescence spectrum of the near-infrared LED light-emitting device of the present invention. Detailed Implementation

[0024] The present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of application of the present invention. The present invention is not limited to the following embodiments or examples. Any modifications and variations made without departing from the spirit of the present invention should be included within the scope of the present invention.

[0025] Example 1: Ca3Sn2Ga2GeO 12 :xFe 3+(0 < x ≤ 0.10) Preparation of Luminescent Materials

[0026] According to the chemical formula Ca3Sn2Ga2GeO 12 :xFe 3+ , 0 < x ≤ 0.10 (in this embodiment, x takes 0.002, 0.005, 0.01, 0.02, 0.03, 0.05, 0.07, 0.10 respectively to prepare the corresponding fluorescent materials: Ca3Sn2Ga2GeO 12 :0.002Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.005Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.01Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.02Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.03Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.05Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.07Fe 3+ 、Ca3Sn2Ga2GeO 12 :0.10Fe 3+ ), accurately weigh the powder raw materials CaCO3, SnO2, Ga2O3, GeO2, Fe2O3. Place the weighed raw materials in an agate mortar, grind until the raw materials are fully and evenly mixed, then transfer them to an alumina corundum crucible, place it in a high-temperature tube furnace, sinter rapidly at 1400 °C for 5 hours, take it out after natural cooling to room temperature, and grind again to obtain the Fe 3+ -activated near-infrared luminescent material. Detect the prepared luminescent material, and the results are as follows:

[0027] As Figure 1 shown in the X-ray diffraction (XRD) pattern, it shows that no impurity phase is generated in the prepared luminescent material, indicating that the phase is a single pure phase. The luminescent material prepared by the present invention has high luminescence brightness and has a wide excitation and emission range. For example Figure 2 shown in the excitation and emission spectra of the Ca3Sn2Ga2GeO 12 :0.02Fe 3+ luminescent material, there are wide and strong excitations in the ultraviolet band (278 nm) and the blue light band (406 nm), and the best emission peak is located at ~756 nm, with a range of 650 - 1000 nm, indicating that it can be well matched with the InGaN semiconductor chip; Figure 3 is Ca3Sn2Ga2GeO12 0.02Fe 3+ The photoluminescence quantum efficiency (PLQY) of the luminescent material was measured, and the results showed that the PLQY measured under 278 nm excitation reached an excellent level of 54.1%. Figure 4 It is Ca3Sn2Ga2GeO 12 0.02Fe 3+ The graph showing the emission intensity of the luminescent material versus temperature reveals that at 423K, its emission intensity still reaches approximately 72% of the initial room temperature condition, demonstrating the efficacy of Fe. 3+ The activated luminescence exhibits robust thermal stability in the material of this invention. This demonstrates the promising potential of the near-infrared luminescent material in high-power near-infrared applications.

[0028] Example 2: Method and Effects of Adding Cosolvents

[0029] According to the preparation method described in Example 1, after weighing each raw material according to the stoichiometric ratio of each element, one of CaF2, NH4F, LiF, Li2CO3, Na2CO3, K2CO3, or H3BO3 can be selected as a solubilizing additive to optimize the luminescence performance of the material. Different types of additives have a certain regulating effect on the luminescence intensity of the final luminescent material. For example, by weighing approximately 5 wt% of Na2CO3 additive into the total mass of the control raw material mixture and thoroughly grinding and mixing it, the near-infrared luminescent material of the present invention can be prepared under the same synthesis conditions as in Example 1. Figure 5 The image shows the preparation of Ca3Sn2Ga2GeO 12 0.02Fe 3+ The comparison of the emission intensity of the sample with added Na2CO3 clearly shows that the emission intensity of the sample with added Na2CO3 is further improved.

[0030] Example 5: Fabrication of a near-infrared LED light-emitting device

[0031] A near-infrared LED light-emitting device: Utilizing the near-infrared light-emitting material, packaging substrate, and blue InGaN semiconductor chip provided by this invention. The near-infrared light-emitting material is a light-emitting material synthesized in Example 1 above, with the chemical formula Ca3Sn2Ga2GeO. 12 :xFe 3+ (x=0.02), i.e. Ca3Sn2Ga2GeO 12 0.02Fe 3+The peak emission wavelength of the blue InGaN semiconductor chip is ~410nm. Near-infrared luminescent material is uniformly dispersed in epoxy resin and coated or dispensed onto the InGaN chip. After high-temperature curing, the circuit is soldered to obtain the near-infrared LED light-emitting device of this invention. The electroluminescence spectrum of the LED light-emitting device is as follows: Figure 6 As shown, blue light-pumped Ca3Sn2Ga2GeO was realized. 12 0.02Fe 3+ Electro-induced near-infrared emission.

[0032] The conventional techniques and solutions not described in detail in the above embodiments are all well known in the art, and therefore will not be elaborated upon here. The above embodiments and / or experimental examples describe the preferred embodiments of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A gallium germanate near-infrared luminescent material with a garnet structure, characterized in that, The chemical formula of the luminescent material is Ca3Sn2Ga2GeO. 12 : x Fe 3+ , where 0 < x ≤ 0.

10.

2. The method for preparing the luminescent material according to claim 1, characterized in that, Includes the following steps: 1) According to the general formula Ca3Sn2Ga2GeO 12 : x Fe 3+ The raw materials of calcium source, tin source, gallium source, germanium source and iron source were accurately weighed according to the stoichiometric ratio, and mixed to obtain a raw material mixture; 2) The raw material mixture from step 1) is calcined in air to obtain a luminescent material. The calcination temperature is 1400-1500 ℃ and the time is 4-8 hours. The obtained luminescent material can be ground into powder.

3. The preparation method according to claim 2, characterized in that, The specific sources of the raw materials mentioned in step 1) are as follows: The calcium source is one or more substances selected from elemental calcium, calcium oxide, and compounds that can be converted into calcium oxide; the tin source is tin oxide; the gallium source is gallium oxide; the germanium source is germanium oxide; and the iron source is iron oxide, magnetite, ferrous oxide, or ferric chloride.

4. The preparation method according to claim 3, characterized in that, The compounds that can be converted into calcium oxide include calcium chlorides, sulfides, carbonates, sulfates, phosphates, and nitrates.

5. The preparation method according to claim 2, characterized in that, The raw material mixture also contains fluxing additives, which are one or more of CaF2, NH4F, LiF, Li2CO3, Na2CO3, K2CO3 and H3BO3.

6. The preparation method according to claim 2, characterized in that, The calcination described in step 2) involves placing the raw material mixture in an alumina corundum crucible for calcination.

7. A near-infrared LED light-emitting device, characterized in that, It includes an LED chip and the luminescent material as described in claim 1, wherein the LED chip is a blue LED chip and the luminescent material is coated on the LED chip.

8. The light-emitting device as claimed in claim 7, characterized in that, The blue LED chip is an InGaN semiconductor chip with an emission wavelength in the range of 405-415nm.

9. The light-emitting device as described in claim 7 or 8, characterized in that, The luminescent material is uniformly dispersed in epoxy resin and then coated onto the LED chip by means of coating or dispensing.

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