Metal halide luminescent material, and preparation method and application thereof

Abstract

This invention belongs to the field of luminescent materials technology, specifically disclosing a metal halide luminescent material, its preparation method, and its application. It involves reacting cuprous halide and tetraethylammonium halide to synthesize crystals emitting blue, white, and yellow light, thus completing the (TEA)₂Cu₂X luminescent material. y The preparation of the crystal enabled tunable emission spectra within the visible light region, resulting in a single-component white light emission crystal (TEA)2Cu2Br2Cl2 with excellent color rendering index and ultra-wideband emission. This single-component white light crystal exhibits ultra-wideband emission characteristics, with a full width at half maximum (FWHM) of 300 nm and CIE coordinates of (0.32, 0.32), very close to the CIE coordinates of pure white light (0.33, 0.33). These characteristics make it an ideal choice for natural white LED applications, and when fabricated into white light emission devices, it achieves a color rendering index as high as 95. Furthermore, it contains no rare earth elements, making it an environmentally friendly material. Its preparation process is simple and low-cost, enabling large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a metal halide luminescent material, its preparation method, and its application. Background Technology

[0002] Artificial lighting is estimated to account for approximately 20% of global electricity consumption and is a significant contributor to carbon dioxide (CO2) emissions, accounting for about 6% of global CO2 emissions. With global urbanization, emissions are further increasing. Therefore, the development of highly efficient and energy-saving luminescent materials and devices is urgently needed. Current solid-state lighting (SSL) devices typically consist of a blue InGaN light-emitting diode (LED) chip combined with (YAG:Ce) 3+ These consist of yellow phosphors or ultraviolet (UV) LED chips combined with a mixture of blue, green, and red phosphors. While these strategies have become mainstream in the lighting market, significant bottlenecks remain in practical applications. Due to YAG:Ce 3+ Lacking red emission, the blue LEDs coated with it emit white light with a poor color rendering index (CRI) (CRI < 80). While multi-component phosphors possess high CRIs, their emission efficiency is low due to self-absorption. Furthermore, varying phosphor degradation rates lead to changes in the emission spectrum of multi-phosphors over time. Moreover, almost all commercial phosphors rely on rare-earth dopants and high-temperature sintering processes, resulting in potential cost, supply, and environmental issues. Therefore, exploring novel single-component white light emitting materials based on Earth-abundant elements is crucial for next-generation SSL applications.

[0003] In recent years, single-component white light emitters have emerged as promising alternatives. These emitters offer numerous advantages, such as no self-absorption, simple device structure, and high color stability, sparking significant interest in the field of artificial lighting. Broadband white light emission from organic-inorganic lead halide hybrids has garnered considerable attention in energy-efficient solid-state lighting (SSL) applications; however, the toxicity of lead in these hybrid materials hinders their commercial prospects. A key parameter in lighting is the color rendering index (CRI), which reflects the ability of a light source to accurately reproduce the colors of an illuminated sample. Indoor lighting requires a CRI greater than 80; however, specific industries with stringent color requirements, such as jewelry, museum galleries, photography, and surgery, require white light emission with a CRI as high as 90. To accurately represent colors, the light source must emit photons covering the entire visible spectrum; however, such broadband emission is difficult to achieve in single-component white light emitters. Generally, a light-emitting diode (LED) chip is covered by one or more phosphors to produce white light emission. However, because the emission of a single phosphor is generally relatively narrow, the resulting white light exhibits poor color rendering. However, mixed phosphors suffer from efficiency loss due to self-absorption, and the different aging rates of individual phosphors cause the emission spectrum to change over time. Therefore, finding single-component white light emitting materials with excellent color rendering index (CRI) and ultra-wideband emission is of great significance to the development of white light-emitting diodes. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a metal halide luminescent material, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a metal halide luminescent material with the chemical formula (TEA)₂Cu₂X. y TEA is a tetraethylammonium halide compound, and X is composed of one or more halogens, namely chlorine (Cl) and bromine (Br).

[0007] Secondly, the present invention provides a method for preparing the above-mentioned metal halide luminescent material, comprising:

[0008] Tetraethylammonium halide (TEA) and cuprous halide were added to a polytetrafluoroethylene liner and mixed with an organic solvent. After heating and reacting, the mixture was cooled to room temperature, and the crystalline product was removed. After washing and drying, crystals (TEA)₂Cu₂X were obtained. y .

[0009] Preferably, the molar ratio of the tetraethylammonium halide compound TEA to the cuprous halide is 1:1.

[0010] Preferably, the tetraethylammonium halide compound TEA is tetraethylammonium bromide TEABr, and the cuprous halide is cuprous chloride CuCl.

[0011] Preferably, the organic solvent is isopropanol.

[0012] Preferably, the tetraethylammonium bromide (TEABr) and cuprous chloride (CuCl) are added to a polytetrafluoroethylene liner and mixed with isopropanol. The mixture is then heated at 100°C for 10 hours, cooled to room temperature, and the crystal product is removed. After washing and drying, a single-component white light crystal (TEA)2Cu2Br2Cl2 is obtained.

[0013] Thirdly, the present invention provides the application of the metal halide luminescent material prepared by the above method in a single-component white light emitting device.

[0014] Preferably, the method for fabricating the single-component white light-emitting device includes:

[0015] (TEA)2Cu2Br2Cl2 crystals were ground into powder, mixed evenly with UV-curable adhesive, and then coated onto 310nm UV lamp beads to prepare a white light emitting device, which emits white light after being powered on.

[0016] The beneficial effects of this invention are:

[0017] This invention involves reacting cuprous halide and tetraethylammonium halide to synthesize a series of crystals, including those emitting blue, white, and yellow light, thus completing the synthesis of (TEA)₂Cu₂X. y The preparation of the crystal enabled tunable emission spectra within the visible light region, resulting in a TEA (2Cu2Br2Cl2) crystal emitting ultra-wideband single-component white light with excellent color rendering index (CRI). This single-component white light crystal exhibits ultra-wideband emission characteristics, with a full width at half maximum (FWHM) of 300 nm and CIE chromaticity coordinates of (0.32, 0.32), very close to the CIE chromaticity coordinates of pure white light (0.33, 0.33). All these characteristics make it an ideal choice for natural white LED applications, and when fabricated into a white light-emitting device, the color rendering index (CRI) reaches as high as 95. Furthermore, this invention does not contain rare earth elements, making it an environmentally friendly material. Its preparation process is simple and low-cost, enabling large-scale industrial production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1The molecular structure diagrams of crystals 1-9 in Example 1 are shown.

[0020] Figure 2 The fluorescence spectra of crystals 1-9 in Example 1 are shown below.

[0021] Figure 3 The CIE chromaticity diagrams of crystals 1-9 in Example 1 are shown.

[0022] Figure 4 The image shows a light-emitting device made using No. 5 as a single-component white light-emitting material in Example 1, illuminated on a colored pencil.

[0023] Figure 5 The thermogravimetric curves of crystals 1-9 in Example 1 are shown. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] Example 1

[0026] Metal halide luminescent materials, with the chemical formula (TEA)₂Cu₂X y TEA is a tetraethylammonium halide compound, and X is composed of one or more halogenated chlorine (Cl) and bromine (Br). Preparation of metal halide luminescent materials: The raw materials were added to polytetrafluoroethylene liners 1-9 according to the component amounts corresponding to 1-9 in Table 1, where TEABr is tetraethylammonium bromide and TEACl is tetraethylammonium chloride. Except for liner 9, which contained 7.5 ml of isopropanol and 7.5 ml of cyclohexane, all other liners contained 15 ml of isopropanol. The liners were sealed with a stainless steel outer reactor and placed in an oven, heated at 100°C for 10 hours. After cooling to room temperature, the crystalline product was removed, washed three times, and then dried in a vacuum drying oven for five hours to obtain dried (TEA)₂Cu₂X. y Crystal sample, its crystal molecular structure is as follows Figure 1 As shown, their structures are similar, only the halogen ratios are different, with number 5 being a single-component white light crystal.

[0027] Table 1 Synthesis Information of Compounds 1-9

[0028] Serial Number Chemical formula CuBr(g) TEABr(g) CuCl(g) TEACl(g) 1 <![CDATA[(TEA)2Cu2Br4]]> 0.287 0.420 2 <![CDATA[(TEA)2Cu2Br 3.5 Cl 0.5 ]]> 0.214 0.420 0.050 3 <![CDATA[(TEA)2Cu2Br3Cl]]> 0.143 0.420 0.099 4 <![CDATA[(TEA)2Cu2Br 2.5 Cl 1.5 ]]> 0.072 0.420 0.148 5 <![CDATA[(TEA)2Cu2Br2Cl2]]> 0.420 0.198 6 <![CDATA[(TEA)2Cu2Br 1.5 Cl 2.5 ]]> 0.315 0.198 0.083 7 <![CDATA[(TEA)2Cu2BrCl3]]> 0.210 0.198 0.166 8 <![CDATA[(TEA)2Cu2Br 0.5 Cl 3.5 ]]> 0.105 0.198 0.2485 9 <![CDATA[(TEA)2Cu2Cl4]]> 0.198 0.331

[0029] (1) Fluorescence spectroscopy analysis

[0030] Fluorescence spectroscopy analysis of crystals 1-9 was performed at room temperature using an Edinburgh-based FLS1000 fluorescence spectrophotometer. Figure 2As can be seen, the emission spectrum is tunable in the visible light region, ranging from blue to white and then to yellow. Furthermore, crystal number 5 exhibits a wide spectral range and ultra-wideband emission characteristics, with a full width at half maximum (FWHM) of 300 nm and CIE coordinates of (0.32, 0.32), very close to the CIE coordinates of pure white light (0.33, 0.33). All these characteristics make it an ideal choice for natural white LED applications.

[0031] (2) Luminescence performance test

[0032] Crystal No. 5 was ground into powder, mixed evenly with UV-curable adhesive, and then coated onto a 310nm UV lamp bead (excitation wavelength 310nm, voltage 5-6.5V, power 0.5-1W) to prepare a white light device, which emits white light when powered on. Figure 3 The chromaticity coordinate diagram shows that its emitted color is very close to pure white light. When the white light device is powered on and shone onto a colored pencil, it can be seen that the white light can clearly display and reproduce the vibrant colors of the colored pencil. Figure 4 The CRI is 95, indicating that the white light has high color rendering properties.

[0033] (3) Thermal stability analysis

[0034] Thermogravimetric analysis was performed on crystals 1-9 within the temperature range of 30-800℃. Figure 5 The thermogravimetric curves show that the phosphor prepared by this invention does not show mass loss and decomposition until around 200℃, indicating that the crystal has good thermal stability.

[0035] Example 2

[0036] Fabrication of single-component white light-emitting devices:

[0037] The No. 5 crystal is ground into powder, then mixed evenly with UV-curing adhesive, and then coated onto a 310nm UV lamp bead (excitation wavelength 310nm, voltage 5-6.5V, power 0.5-1W) to prepare a white light device, which emits white light after being powered on.

[0038] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A method for preparing a metal halide luminescent material, characterized in that, include: Tetraethylammonium bromide (TEABr) and cuprous chloride (CuCl) were added to a polytetrafluoroethylene liner and mixed with isopropanol. The mixture was heated at 100°C for 10 hours, cooled to room temperature, and the crystal product was removed. After washing and drying, a single-component white light crystal (TEA)2Cu2Br2Cl2 was obtained. The molar ratio of tetraethylammonium bromide (TEABr) to cuprous chloride (CuCl) is 1:

1.

2. The application of the metal halide luminescent material prepared according to claim 1 in a single-component white light emitting device.

3. Use according to claim 2, characterized in that, include: (TEA)2Cu2Br2Cl2 crystals were ground into powder, mixed evenly with UV-curable adhesive, and then coated onto 310nm UV lamp beads to prepare a white light emitting device, which emits white light after being powered on.

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