Red emitting nitridophosphate phosphor and white phosphor converted leds

Abstract

An inventive luminescent material suitable for use as a phosphor for LEDs, comprising a nitridophosphate material having the general chemical formula AE y‑x Li 10‑2y P4N 10 :Eu x wherein (i) AE comprises one or more of Ca, Sr, or Ba, and (ii) y > x > 0. In some examples, y can equal = 2 and x can be between 0 and 0.1. In some examples, AE can comprise only Ca; in some other examples, AE can comprise a majority amount of Ca and a lesser amount of Sr or Ba. In some examples, the luminescent material can exhibit a peak emission wavelength greater than 600 nm.

Description

[0001] Priority requirements This application claims priority to U.S. nonprovisional application No. 18 / 540,203, filed December 14, 2023, by Schmidt et al., entitled “Red-emitting nitridophosphate phosphor and white phosphor-converted LED,” which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention generally relates to phosphor-converted light-emitting diodes (pcLEDs). Background Technology

[0005] Semiconductor light-emitting diodes and laser diodes (collectively referred to herein as "LEDs") are among the most efficient light sources currently available. The emission spectrum of an LED typically exhibits a single, narrow peak at a wavelength determined by the device's structure and the composition of the semiconductor materials it constitutes. By appropriately selecting the device structure and material system, LEDs can be designed to operate at ultraviolet, visible, or infrared wavelengths. In some instances, the light emitted by an LED is used as the device's output; such LEDs can be referred to as direct emitters.

[0006] In other instances, LEDs can be combined with one or more wavelength conversion materials (generally referred to herein as "phosphors") that absorb the light emitted by the LED and, in response, emit longer wavelength light. For such phosphor-converting LEDs ("pcLEDs"), the proportion of light emitted by the LED that is absorbed by the phosphor depends on the amount of phosphor material in the optical path of the light emitted by the LED, for example, on the concentration of phosphor material in a phosphor layer disposed on or around the LED and the thickness of that layer.

[0007] Phosphor-converted LEDs can be designed such that all light emitted by the LED is absorbed by one or more phosphors, in which case the emission from the pcLED originates entirely from the phosphor. In this case, for example, the phosphor can be selected to emit light in a narrow spectral region that cannot be efficiently generated directly by the LED.

[0008] Alternatively, a pcLED can be designed such that only a portion of the light emitted by the LED is absorbed by the phosphor. In this case, the emission from the pcLED is a mixture of light emitted by the LED and light emitted by the phosphor. By appropriately selecting the LED, phosphor, and phosphor components, such a pcLED can be designed to emit white light, for example, with a desired color temperature and desired color rendering properties.

[0009] Multiple LEDs or pcLEDs can be formed together on a single substrate to form an array. Such arrays can be used to form active lighting displays, such as those used in smartphones and smartwatches, computer or video displays, signage, or visualization systems (such as augmented or virtual reality displays); or to form adaptive lighting sources, such as those used in motor vehicle headlights, street lighting, camera flash sources, or flashlights (i.e., flashlights). Arrays with one or more individual devices per millimeter (e.g., device spacing or intervals of approximately one millimeter, several hundred micrometers, or less than 100 micrometers, and separations of less than 100 micrometers or only tens of micrometers or less between adjacent devices) are generally referred to as miniLED arrays or microLED arrays (alternatively, μLED arrays). Such miniLED arrays or microLED arrays may also include phosphor converters as described above in many instances; such arrays may be referred to as pc-miniLED arrays or pc-microLED arrays. Summary of the Invention

[0011] An inventive luminescent material suitable for use as a phosphor in LEDs, comprising materials having the universal chemical formula AE y-x Li 10- 2y P4N 10 Eu x The luminescent material is a nitrogen-phosphate material, wherein (i) AE comprises one or more of Ca, Sr, or Ba, and (ii) y ≥ x > 0. In some instances, y may be equal to 2 and x may be between 0 and 0.1. In some instances, AE may comprise only Ca; in other instances, AE may comprise a majority amount of Ca and a smaller amount of Sr or Ba. In some instances, the luminescent material may exhibit a peak emission wavelength greater than 600 nm.

[0012] The objectives and advantages associated with pcLED, pc-miniLED arrays and pc-microLED arrays may become clear when referenced to the illustrations in the accompanying drawings and the examples disclosed in the following written description or appended claims.

[0013] This summary is provided to present a simplified description of selected concepts, which are further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter. Attached Figure Description

[0015] Figure 1 A schematic cross-sectional view of an example pcLED is shown.

[0016] Figure 2A and Figure 2B A cross-sectional schematic view and a top view of the pcLED example array are shown respectively. Figure 2C A top view schematic diagram of an example miniLED or microLED array and a magnified partition of the array's 3x3 LEDs is shown.

[0017] Figure 3A A schematic cross-sectional view of an example array of pcLEDs arranged relative to waveguides and projection lenses is shown. Figure 3B It shows the relationship with Figure 3A It has a similar arrangement, but without waveguides.

[0018] Figure 4A A schematic top view of an example electronic board on which a pcLED array can be mounted is shown, and Figure 4B Similarly, installations are shown. Figure 4A An example pcLED array on an electronic board.

[0019] Figure 5A , Figure 5B and Figure 5C The crystal structure of an example inventive nitrogen phosphate luminescent material is illustrated schematically. Figure 5D The illustration shows an example of an inventive nitrogen phosphate luminescent material's X-ray diffraction pattern. Figure 5E This is an electron micrograph of a sample of an example of an inventive nitrogen phosphate luminescent material. Figure 5F and Figure 5G This is a crystallographic data sheet for an example of an invented nitrogen phosphate luminescent material. Figure 5H The illustration shows the low-temperature emission spectrum of an example inventive nitrogen phosphate luminescent material.

[0020] Figure 6A and Figure 6B The emission and absorption spectra of an example of an inventive nitrogen phosphate luminescent material and several conventional CASN luminescent materials are shown respectively.

[0021] Figure 7AThis is a table showing phosphor compositions comprising a green-emitting material mixed with an example of an inventive nitrogen-phosphate luminescent material and four example conventional SCASN or CASN luminescent materials. Figure 7B and Figure 7C The diagram illustrates the process of... Figure 7A The output spectrum produced by the mixture; Figure 7D and Figure 7E The diagram illustrates the process of... Figure 7A The color produced by the mixture.

[0022] The examples depicted are merely illustrative; all features may not be shown in full detail or to the proper scale; for clarity, some features or structures may be exaggerated or reduced relative to others, or omitted entirely; the figures should not be considered to scale unless explicitly indicated otherwise. For example, the vertical dimensions or layer thicknesses of individual LEDs may be exaggerated relative to their lateral extent or relative to the thickness of the substrate or phosphor. The examples shown should not be construed as limiting the scope of this disclosure or the appended claims. Detailed Implementation

[0024] The following detailed description should be read with reference to the accompanying drawings, in which the same reference numerals refer to similar elements throughout the various figures. The drawings, which are not necessarily to scale, depict selective examples and are not intended to limit the scope of the subject matter of the invention. The detailed description illustrates the principles of the subject matter of the invention by way of example, not by way of limitation. For the purposes of simplicity and clarity, detailed descriptions of well-known devices, circuits, and methods may be omitted so as not to obscure the description of the subject matter of the invention with unnecessary detail.

[0025] Figure 1 An example of a standalone pcLED 100 is shown, which includes a semiconductor light-emitting diode (LED) structure 102 disposed on a substrate 104 and a wavelength conversion structure (e.g., a phosphor layer) 106 disposed on the semiconductor LED.

[0026] Semiconductor LED structure 102 typically includes a junction or active region disposed between an n-type layer and a p-type layer. Applying a suitable forward bias voltage across semiconductor LED structure 102 causes light emission from the active region. The wavelength of the emitted light (i.e., a first wavelength) is determined by the composition and structure of the active region. The semiconductor LED 102 can be, for example, a group III nitride LED that emits blue, violet, or ultraviolet light. LEDs formed from any other suitable material system and emitting light of any other suitable wavelength can also be used. Other suitable material systems may include, for example, group III phosphide materials, group III arsenide materials, other binary, ternary, or quaternary alloys of gallium, aluminum, indium, nitrogen, phosphorus, and arsenic, other group III-V materials, or various group II-VI materials.

[0027] Depending on the desired optical output from the pcLED, a variety of suitable light-emitting materials can be used or incorporated into the wavelength conversion structure 106. At least a portion of the first light is absorbed by the light-emitting material of the wavelength conversion structure 106, which in turn emits light of a second wavelength longer than the first wavelength. In some examples, the wavelength conversion structure may include one or more additional light-emitting materials that absorb the first wavelength and emit light of one or more corresponding additional wavelengths longer than the first wavelength. The light output of the pcLED includes light emitted at the second wavelength by the light-emitting material of the wavelength conversion structure, and may also include light emitted by one or more additional light-emitting materials of the wavelength conversion structure 106 (if present). In some examples, the light output of the pcLED 100 may include some of the first wavelength light emitted by the semiconductor LED structure 102; in some other examples, the first wavelength light may not be present or may only be negligibly present in the light output of the pcLED 100.

[0028] Figures 2A-2B Cross-sectional and top views of a 3x3 array 200 of pcLEDs 100 disposed on a substrate 204 are shown, each pcLED 100 including a phosphor pixel 106. Typically, the array can include any suitable number of LEDs arranged in any suitable manner. In the illustrated example, the array is depicted as monolithically formed on a shared substrate; however, alternatively, the array can be formed from separate individual LEDs and / or pcLEDs (e.g., singulated devices assembled onto the array substrate). Individual phosphor pixels 106 are shown in the illustrated example; however, alternatively, a continuous layer of phosphor material can be disposed across multiple semiconductor LEDs 102. In some instances, the array 200 can include light barriers (e.g., reflection, scattering, and / or absorption) between adjacent semiconductor LEDs 102, phosphor pixels 106, or both. The substrate 204 may optionally include traces or interconnects, or CMOS or other circuitry for driving the LEDs, and can be formed of any suitable material.

[0029] although Figure 2A and Figure 2B A 3×3 array of nine pcLEDs is shown, but such arrays can include, for example, arrays of 10 pcLEDs. 1 10 2 10 3 10 4 or more LEDs and / or pcLEDs, for example, Figure 2C The diagram illustrates the process. Individual LEDs 100 (i.e., pixels) can have a width w1 (e.g., side length) in the plane of array 200, for example, less than or equal to 1 millimeter (mm), less than or equal to 500 micrometers, less than or equal to 100 micrometers, or less than or equal to 50 micrometers. The LEDs 100 in array 200 can be spaced apart from each other by streets, lanes, or trenches 230 having a width w2 in the plane of array 200, for example, several hundred micrometers, less than or equal to 100 micrometers, less than or equal to 50 micrometers, less than or equal to 20 micrometers, less than or equal to 10 micrometers, or less than or equal to 5 micrometers. The pixel pitch or spacing D1 is the sum of w1 and w2. While the illustrated example shows rectangular pixels arranged in a symmetrical matrix, these pixels and arrays can have any suitable shape or arrangement, whether symmetrical or asymmetrical. Multiple separate LED arrays can be combined in any suitable arrangement in any applicable format to form a larger combined array or display.

[0030] LEDs with a dimension w1 (e.g., side length) less than or equal to about 0.10 millimeters / micrometers in an array plane are generally called microLEDs, and an array of such microLEDs can be called a microLED array. LEDs with a dimension w1 (e.g., side length) between about 0.10 millimeters and about 1.0 millimeters in an array plane are generally called miniLEDs, and an array of such miniLEDs can be called a miniLED array.

[0031] Individual LEDs (pixels) in an LED array can be individually addressable, addressable as part of a group or subset of pixels in the array, or not addressable. Therefore, luminescent pixel arrays are useful for any application that requires or benefits from fine-grained intensity, spatial, and temporal control of light distribution. These applications can include, but are not limited to, precise, specific patterning of emitted light from pixel blocks or individual pixels, and in some instances, forming images as a display device. Depending on the application, the emitted light can be spectrally distinct, time-adaptive, and / or environmentally responsive. Luminescent pixel arrays can provide pre-programmed light distributions with various intensity, spatial, or temporal patterns. The emitted light can be at least partially based on received sensor data and can be used for optical wireless communication. The associated electronics and optics can be distinctly different at the pixel, pixel block, or device level.

[0032] Optionally, each pcLED 100 may include, or be arranged in combination with, a lens or other optical element positioned adjacent to or disposed on the phosphor layer. Such an optical element (not shown in the figures) may be referred to as a “primary optical element” and may have any suitable type of arrangement (e.g., conventional refractive or diffractive optical elements, or so-called nanostructured optical elements, such as those disclosed in U.S. Patent No. 11,327,283, U.S. Publication No. 2020 / 0343416, U.S. Publication No. 2020 / 0335661, U.S. Publication No. 2021 / 0184081, U.S. Publication No. 2022 / 0146079, or U.S. Publication No. 2022 / 0393076, each of which is incorporated herein by reference in its entirety). Additionally, as Figure 3A and Figure 3B As shown, the pcLED array 200 (e.g., mounted on an electronics board) can be arranged in combination with secondary optical elements (such as waveguides, lenses, or both) for the intended application (for the entire array, for a subset of the entire array, or for individual pixels; for any suitable type or arrangement, such as conventional refractive or diffractive optical elements, or so-called nanostructure optical elements, including any of those listed above). Figure 3A In this arrangement, the light emitted by each pcLED 100 of array 200 is collected by a corresponding waveguide 192 and guided to projection lens 294. For example, projection lens 294 may be a Fresnel lens. This arrangement can be suitable for use in motor vehicle headlights or other adaptive lighting sources. Each pixel may include other primary or secondary optical elements of any suitable type or arrangement, as needed or desired. Figure 3BIn this arrangement, the light emitted by the pcLEDs of array 200 is directly collected by projection lens 294 without the use of an intermediate waveguide. This arrangement can be particularly suitable when the pcLEDs can be spaced sufficiently close to each other, and can also be used in automotive headlights, camera flash applications, or other lighting sources. For example, miniLED or microLED display applications can use... Figures 3A-3B The optical arrangement is similar to that described herein. Generally, depending on the desired application, any suitable arrangement of optical elements (primary, secondary, or both) can be used in combination with the pcLED described herein.

[0033] like Figure 4A and Figure 4B As shown, the pcLED array 200 can be mounted on an electronics board 300, which includes a power and control module 302, a sensor module 304, and an LED attachment area 306. The power and control module 302 can receive power and control signals from an external source and signals from the sensor module 304, based on which it controls the operation of the LEDs. The sensor module 304 can receive signals from any suitable sensor, such as a temperature or light sensor. Alternatively, the pcLED array 200 can be mounted on a separate board (not shown) from the power and control module and the sensor module.

[0034] For the purposes of this disclosure and the appended claims, any arrangement of a layer, surface, substrate, diode structure, or other structure “on,” “above,” or “immediately” to another such structure shall encompass arrangements having direct contact between the two structures and arrangements including some intervening structures between them. Conversely, any arrangement of a layer, surface, substrate, diode structure, or other structure “directly on,” “directly above,” or “directly immediately” to another such structure shall only encompass arrangements having direct contact between the two structures. For the purposes of this disclosure and the appended claims, layers, structures, or materials described as “transparent” and “substantially transparent” shall exhibit sufficiently high optical transmittance levels or sufficiently low optical loss levels (due to absorption, scattering, or other loss mechanisms) at the relevant wavelengths, such that the light-emitting device can function within operationally acceptable parameters (e.g., output power or brightness, conversion or extraction efficiency, or other quality factors including those described below).

[0035] A luminescent material (i.e., a phosphor) is required that absorbs near-UV or blue light (e.g., light with a first wavelength less than 500 nm) and subsequently emits red light (e.g., light with a second wavelength longer than 600 nm). Such a red-emitting luminescent material can be used to generate red light, for example, as part of an RGB display, or it can be used to generate white light, for example, along with light emitted by one or more other phosphors or by a first wavelength emitted by a semiconductor LED. Several conventional red-emitting Eu(II)-doped nitride luminescent materials can be used, such as CASN (CaAlSiN3:Eu). 2+ ) or SCASN ((Sr,Ca)AlSiN3:Eu 2+ ) material or BSSNE ((Ba,Sr,Ca)2Si5N8:Eu 2+ )Material.

[0036] However, there remains a persistent need for red-emitting luminescent materials that offer improved luminous efficiency while providing acceptable color reproduction quality or color saturation. Therefore, this paper discloses examples of inventive nitrogen-phosphate luminescent materials (i.e., phosphors) characterized by a narrower spectral power distribution of the emission band compared to the conventional red-emitting luminescent materials described above, and these examples are well-suited for applications such as CRI90 white pcLEDs. The red-emitting luminescent material disclosed herein mitigates a problem of conventional red-emitting luminescent materials (such as SCASN / CASN)—a broad emission spectrum caused by multiple emission centers—by providing a main lattice with only one site for the emission center.

[0037] One luminescent material comprises a nitrogen phosphate material having the general chemical formula AE. y-x Li 10-2y P4N 10 Eu xWherein (i) AE comprises one or more of Ca, Sr, or Ba, and (ii) y ≥ x > 0. Specifically, a red-emitting luminescent material is obtained when y = 2 and 0.1 > x > 0. Other similar materials having, for example, y = 3 or y = 4 crystallize in a structure different from the structure obtained when y = 2, and those other materials exhibit emission at shorter wavelengths. In some examples of y = 2, the luminescent material exhibits a peak emission wavelength greater than 600 nm; in examples where AE = Ca, y = 2, and x = 0.01, the luminescent material exhibits a peak emission wavelength at 626 nm. In some examples of the inventive luminescent material, AE comprises only Ca. In some other examples, AE comprises a majority amount of Ca and a smaller amount of Sr or Ba; the inclusion of Sr or Ba shifts the emission to a shorter wavelength. Therefore, the position of the peak emission can be tuned by adjusting the ratio of different AE atoms in the inventive luminescent material. Increasing the Eu doping concentration (i.e., increasing x) results in stronger absorption and a shift of the peak emission to a longer wavelength, making it possible to tune the absorption or emission characteristics of the inventive luminescent material to a certain extent.

[0038] In some examples, (i)Li can be tested at isostatic nitrogen pressures ranging from 50 MPa to 200 MPa and temperatures ranging from 800°C to 1000°C. 10 P4N 10 The luminescent material of the invention is prepared by performing a solid-state reaction of (ii) halides, hydrides, azides, or nitrides of AE and (iii) halides or oxides of Eu. In one example, the reaction proceeds to Li 10 P4N 10 +(yx)AECl2+(x)EuCl2→AE y-x Li 10_2y P4N 10 Eu x + (y+x) LiCl. The LiCl formed by the solid-state reaction can be removed, for example, by washing the luminescent material with ethanol.

[0039] In a specific example, 33.34g of Li 10 P4N 10 21.97 g CaCl2 and 0.45 g EuCl2 were mixed and calcined in an isostatic pressure furnace at 900 °C for 10 hours under a nitrogen pressure of 200 MPa. After calcination, the original product was washed with ethanol to remove LiCl, ground in ethanol with zirconium oxide grinding media, and then dried. Figure 5D The obtained Ca2Li6P4N is shown. 10 X-ray powder diffraction pattern of Eu(1%) phosphor. Figure 5E A scanning electron microscope image of the powder sample is shown.

[0040] The crystal structure of the invented luminescent material [P4N] 10 ] 10- Construction block ( Figure 5A This indicates the use of Li 10 P4N 10 The expectation as a starting material. In some examples, Li 10 P4N 10 The precursor can be derived from W. Schnick, U. Berger, Angew. Chem. Int. Ed. Engl. The method described in 30 (1991) 830-831 (incorporated herein by reference in its entirety) synthesizes from the binary nitrides Li3N and P3N5 via a solid-state reaction. In a particular example, 35.0 g of Li3N and 65.18 g of P3N5 (according to W. Schnick, J. Lücke, F. Krumreich, ...) were reacted by planetary ball milling. Chem. Mater. 8(1996) 281–286 (which is incorporated herein by reference in its entirety) synthesized) mixed and calcined at 800 °C under a nitrogen pressure of 50 MPa.

[0041] In some examples, the luminescent compounds of the invention can be prepared by performing a solid-state reaction on a mixture of (i) AE2PN3:Eu, (ii) LiPN2, and (iii) Li3N at an isostatic nitrogen pressure of 50 MPa to 200 MPa and a temperature of 800 °C to 1000 °C. In some examples, the luminescent materials of the invention can be prepared according to (Ca,Sr)2PN3:Eu + 5 LiPN2 + (1 / 3)Li3N → (Ca,Sr)2Li6P4N. 10 Eu preparation. Lithium nitride is melted at approximately 814 °C; in some examples, lithium nitride can be used as a flux. In some examples, a small excess of lithium nitride forms a reinforcing phase and can be used to control the grain size of the phosphor powder produced by the reaction.

[0042] In some other examples, other starting materials can be used for phosphor synthesis. For example, hydrides, azides, or nitrides can be used as AE sources, such as AE(N3)2, AEH2, AE2N, or AE3N2. These precursors can be combined with Li3N or LiN3 as a Li source and P (red) or P3N5 as a P source. For Eu doping, compounds such as chlorides, fluorides, or oxides of Eu can be used. Alternatively, in some examples, alkaline earth or lithium phosphides such as AE3P2, AEP3, AE2P2, AE5P8, LiP, or Li3P can be used as precursors for synthesizing the inventive nitrogen-phosphate luminescent material. In some examples, Ca3P2 can be formed by carbothermal reduction (Ca3(PO4)2 + 8C → Ca3P2 + 8CO). In some examples, more complex precursor materials can be used for the synthesis of the inventive luminescent material. In some examples, ternary nitrogen-phosphates, such as LiPN2, Li 12 P3N9, Li7PN4, Li6P3N7, Li5P2N5 or Ca2PN3.

[0043] AE 2-x Li6P4N 10 Eu x (AE = Ca, Sr, Ba) crystallizes in the tetragonal space group I4̄2d (Nr. 122). For AE = Ca, the lattice parameters are a = b = 9.891 Å and c = 9.592 Å. Figure 5F and 5G The table shown includes data from... Figure 5D The crystal structure analysis data derived from the X-ray diffraction pattern shown is illustrated. The crystal structure of the luminescent material of this invention [P4N] 10 ] 10- Constructor blocks in Figure 5A The diagram is schematically illustrated. Figure 5B The schematic diagram illustrates a unit cell of a crystal structure comprising four chemical formula units. (The unit cell is filled with Eu atoms.) Figure 5B The AE atoms (partially substituted in the largest sphere) are located at a lattice site coordinated by 6 N atoms, forming a deformed octahedron, such as... Figure 5C The schematic diagram shows that a single lattice site of Eu dopant results in a clearly distinguishable zero-phonon emission line under blue light excitation and low phosphor temperatures. Figure 5H ).

[0044] In some examples, a phosphor particle coating can be applied to the original phosphor particles to enhance the long-term reliability of the phosphor powder. In some examples, such a coating can be formed, for example, by an atomic layer deposition (ALD) process or by a sol-gel coating process. Examples are disclosed, for example, in U.S. Patent Publication No. 2021 / 0403805, the entire contents of which are incorporated herein by reference.

[0045] An inventive wavelength conversion structure comprising a structure having the universal chemical formula AE y-x Li 10-2y P4N 10 Eu x The nitrogen-phosphate material, wherein (i) AE comprises one or more of Ca, Sr, or Ba, and (ii) y ≥ x > 0, includes any example shown or described herein. A method for preparing the wavelength conversion structure of this invention comprises bonding particles of the luminescent material of the invention together in a polymer (e.g., silicone) or ceramic binder material. As described above, in some examples, a particulate coating may be formed on the particles of the luminescent material prior to bonding them together. In some examples, particles of one or more additional luminescent materials may be mixed with the particles of the luminescent material of the invention prior to bonding. The mixture of luminescent material particles can then be bonded using a polymer or ceramic binder material.

[0046] The light-emitting device of the invention may include a group III nitride light-emitting diode (LED 102) and an inventive wavelength conversion structure 106 comprising an inventive luminescent material, including any of those luminescent materials shown or described herein. The LED 102 (e.g., a group III nitride LED) may be arranged to emit light of a first wavelength (e.g., shorter than 500 nm) that is at least partially absorbed by the inventive luminescent material. The luminescent material absorbs at least some of the first wavelength of light and subsequently emits light of a second longer wavelength (e.g., longer than 600 nm). The light-emitting device may be operated by supplying current to the semiconductor LED 102 such that (i) the semiconductor LED 102 emits light of the first wavelength, and (ii) the absorption of at least a portion of the first wavelength of light by the luminescent material of the wavelength conversion structure 106 results in the emission of light of the second wavelength. The output light of the light-emitting device 100 includes light of the second wavelength. In some examples, the first wavelength of light may be absent or only negligibly present in the output light of the light-emitting device 100; in such examples, the output light may be red, allowing the light-emitting device to act as, for example, a red pixel in an RGB display. In some other examples, a portion of the light of the first wavelength may be included in the output light of the light-emitting device; in such examples, the output light may be, for example, white light produced by a mixture of light of the first and second wavelengths. In some of those examples, the wavelength conversion structure 106 may include one or more additional light-emitting materials that emit one or more additional wavelengths of light longer than the first wavelength.

[0047] An example of the luminescent material of the invention (Ca2Li6P4N) 10 Eu(1%) ； exist Figure 6A , 6B (As specified in 7A-7E as examples) are compared with several conventional red-emitting luminescent materials (specified as SCASN, CASN1, CASN2 and CASN3, for example, derived from Mitsubishi Chemical Corporation and labeled as BR3 / 639A, BR101 / N, BR101 / J and BR101 / D respectively). Figure 6A A comparison of normalized emission spectra obtained under 440 nm excitation is shown. Figure 6BA comparison of normalized excitation spectra is shown. Example: The inventive and conventional luminescent materials, each mixed in a two-component silicone resin with a green-emitting Ce(III)-doped yttrium aluminum gallium garnet phosphor, with a unit cell constant a = 12.09 Å and a Ga / Al ratio of 1 / 2, exhibit an emission radiative luminescence efficiency (LER) of 465 lm / W. For each red-emitting phosphor (inventive and conventional), two samples were prepared: one exhibiting a correlated color temperature (CCT) of 2700 K and the other exhibiting a CCT of 4000 K; the parameters of the samples are as follows: Figure 7A The results are shown in the table. The phosphor in the silicone suspension was then dispensed into a 2.8 x 3.5 mm² leadframe LED package equipped with a blue InGaN die (440 nm centroid wavelength). After curing the silicone resin, the resulting pcLED was characterized at 25°C and an LED current of 120 mA.

[0048] Figure 7B and Figure 7C The spectral power distributions of white pcLEDs with correlated color temperatures of 2700 and 4000 K are shown respectively. The sample with a correlated color temperature of 2700 K exhibits CIE x,y color coordinates x = 0.485, y = 0.410; the sample with a color temperature of 4000 K exhibits CIE x,y color coordinates x = 0.382, y = 0.380. A decrease in spectral power can be observed in the deep red (>650 nm) range of the white pcLEDs, including the invented nitrogen-phosphate phosphor. This reduced deep red light content not only leads to an increase in luminous efficiency but also results in… Figure 7D and 7E The increase in light quality, measured by the average color rendering index Ra8, is shown for correlated color temperatures of 2700 and 4000 K.

[0049] In addition to the foregoing, the following exemplary embodiments fall within the scope of this disclosure or the appended claims: Example 1. A luminescent material comprising a material having the general chemical formula AE y-x Li 10-2y P4N 10 Eu x Nitrogen phosphate materials, wherein (i) AE includes one or more of Ca, Sr or Ba, and (ii) y ≥ x>0.

[0050] Example 2. The luminescent material according to Example 1, where y = 2 and 0.1 > x > 0.

[0051] Example 3. The luminescent material according to any one of Examples 1 or 2, wherein AE comprises only Ca.

[0052] Example 4. The luminescent material according to any one of Examples 1 or 2, wherein the AE comprises a majority amount of Ca and a smaller amount of Sr or Ba.

[0053] Example 5. The luminescent material according to any one of Examples 1 to 4 exhibits a peak emission wavelength greater than 600 nm.

[0054] Example 6. A method for preparing a luminescent material according to any one of Examples 1 to 5, the method comprising reacting (i)Li with nitrogen at an isostatic pressure of 50 MPa to 200 MPa and a temperature of 800 °C to 1000 °C. 10 P4N 10 (ii) A mixture of halides, hydrides, azides or nitrides of AE and (iii) halides or oxides of Eu performs solid-state reactions.

[0055] Example 7. The method according to Example 6 further includes washing the luminescent material to remove LiCl formed by the solid-state reaction.

[0056] Example 8. A method for preparing a luminescent material according to any one of Examples 1 to 5, the method comprising performing a solid-state reaction on a mixture of (i) AE2PN3:Eu, (ii) LiPN2 and (iii) Li3N at an isostatic nitrogen pressure of 50 MPa to 200 MPa and at a temperature of 800 °C to 1000 °C.

[0057] Example 9. A wavelength conversion structure comprising a luminescent material according to any one of Examples 1 to 5.

[0058] Example 10. A method for preparing a wavelength conversion structure according to Example 9, the method comprising bonding particles of a luminescent material together in a polymeric or ceramic binder material.

[0059] Example 11. A method for preparing a wavelength conversion structure according to Example 9, the method comprising (i) mixing particles of a luminescent material with particles of one or more additional luminescent materials, and (ii) bonding the particles of the luminescent material and the particles of one or more additional luminescent materials together in a polymer or ceramic binder.

[0060] Example 12. The method according to any one of Examples 10 or 11 further includes forming a particulate coating on the particles of the luminescent material(s) before bonding the particles of the luminescent material(s) together.

[0061] Example 13. A light-emitting device comprising a group III nitride light-emitting diode (LED) and a wavelength conversion structure according to Example 9, wherein the LED is arranged to emit light of a first wavelength that is at least partially absorbed by a light-emitting material, the light-emitting material exhibiting emission of light of a second wavelength, the emission being caused by the absorption of the first wavelength light, the second wavelength being longer than the first wavelength.

[0062] Example 14. A light-emitting device comprising a group III nitride light-emitting diode (LED) and a wavelength conversion structure according to Example 9, wherein the LED is arranged to emit light of a first wavelength less than 500 nm, the light being at least partially absorbed by a light-emitting material of the wavelength conversion structure, the light-emitting material exhibiting emission of light of a second wavelength greater than 600 nm, the emission being caused by the absorption of the first wavelength light.

[0063] Example 15. A method for operating a light-emitting device according to any one of Examples 13 or 14, the method comprising supplying a current to an LED such that (i) the LED emits light of a first wavelength, and (ii) absorption of at least a portion of the first wavelength light by a light-emitting material of a wavelength conversion structure results in the emission of light of a second wavelength, the second wavelength light being included in the output light of the light-emitting device.

[0064] Example 16. According to the method described in Example 15, light of the first wavelength is absent or only negligibly present in the output light of the light-emitting device.

[0065] Example 17. According to the method described in Example 15, a portion of the light of the first wavelength is included in the output light of the light-emitting device.

[0066] Example 18. The method according to any one of Examples 15 to 17, wherein the wavelength conversion structure includes one or more additional light-emitting materials, the absorption of at least a portion of light of a first wavelength by each of the one or more additional light-emitting materials of the wavelength conversion structure resulting in the emission of light of a corresponding additional wavelength longer than the first wavelength, and the output light of the light-emitting device includes light emitted by the one or more additional light-emitting materials of the wavelength conversion structure.

[0067] This disclosure is illustrative and not restrictive. Further modifications will be apparent to those skilled in the art in light of this disclosure and are intended to fall within the scope of this disclosure or the appended claims. It is intended that equivalents of the disclosed exemplary embodiments and methods, or modifications thereof, should fall within the scope of this disclosure or the appended claims.

[0068] In the foregoing specific embodiments, various features from several example embodiments may be combined for the purpose of streamlining the disclosure. This method of disclosure should not be construed as reflecting an intention that any claimed embodiment requires more features than expressly listed in the corresponding claim. Rather, as reflected in the appended claims, the inventive subject matter may lie in fewer than all features of any single disclosed example embodiment. Therefore, this disclosure should be interpreted as implicitly disclosing any embodiment having any suitable subset of one or more features shown, described, or claimed in this application, including those subsets that may not be expressly disclosed herein. A “suitable” subset of features includes only features that are neither incompatible nor mutually exclusive with respect to that subset. Therefore, the appended claims are thus incorporated into the specific embodiments in their entirety, with each claim itself serving as a separately disclosed embodiment. Furthermore, each of the appended dependent claims should be interpreted as being solely for the purpose of disclosure by incorporating the claims into the specific embodiments, as if written in multiple dependent forms and subordinate to all the foregoing claims that do not contradict them. It should also be noted that the cumulative scope of the appended claims may, but does not necessarily, cover all the subject matter disclosed in this application.

[0069] The following interpretations shall apply to the purposes of this disclosure and the appended claims. Unless expressly stated otherwise, the words “comprising,” “including,” “having,” and variations thereof, wherever they appear, shall be understood as open-ended terms meaning as if a phrase such as “at least” were appended after each instance. The article “a” shall be interpreted as “one or more” unless “only one,” “single,” or other similar limitation is expressly stated or implied in the particular context; similarly, the article “the” shall be interpreted as “one or more of…” unless “only one of…,” “single of…,” or other similar limitation is expressly stated or implied in the particular context. The conjunction “or” shall be interpreted as inclusive unless: (i) it is otherwise expressly stated, for example, by using “or…or…,” “only one of…,” or similar language; or (ii) two or more of the listed alternatives are understood or disclosed (implicitly or explicitly) as incompatible or mutually exclusive in the particular context. In the latter case, “or” will be understood to cover only those combinations involving non-mutually exclusive alternatives. In one example, each of “dog or cat,” “one or more dogs or cats,” and “one or more dogs or cats” will be interpreted as one or more dogs without any cats, or one or more cats without any dogs, or one or more of each.

[0070] For the purposes of this disclosure or the appended claims, when enumerating numerical values ​​(with or without terms such as “about,” “about equal to,” “substantially equal to,” “greater than about,” “less than about,” etc.), standard conventions relating to measurement accuracy, rounding error, and significant figures shall apply, unless a different interpretation is explicitly stated. For null values ​​described by phrases such as “prevent,” “not present,” “eliminate,” “equal to zero,” “negligible,” etc. (with or without terms such as “substantially” or “about”), each such phrase should indicate that the quantity in question has been reduced or diminished to such an extent that, in the context of the intended operation or use of the disclosed or claimed device or method, for practical purposes, the overall behavior or performance of the device or method would be no different from that which would have occurred if the zero quantity had been completely removed, precisely equal to zero, or otherwise precisely zero.

[0071] For the purposes of this disclosure and the appended claims, any designation (e.g., first, second, third, etc., (a), (b), (c), etc., or (i), (ii), (iii), etc.) of elements, steps, limitations, or other parts of the embodiments, examples, or claims is merely for clarity and should not be construed as implying any kind of order or priority of such designations. If any such order or priority is intentional, it will be expressly enumerated in the embodiments, examples, or claims, or in some instances, it will be implicit or inherent based on the specific content of the embodiments, examples, or claims. In the appended claims, if it is expected that the provisions of 35 USC §112(f) will be invoked in a device claim, the word “apparatus” will appear in that device claim. If it is expected that those provisions will be invoked in a method claim, the word “for the step of…” will appear in that method claim. Conversely, if the words “apparatus” or “for the step of…” do not appear in the claim, then the provisions of 35 USC §112(f) are not intended to be invoked in that claim.

[0072] If any one or more disclosures are incorporated herein by reference and such incorporated disclosures conflict in whole or in part with this disclosure, or differ in scope from this disclosure, then this disclosure shall prevail as to the extent of the conflict, the broader disclosure, or the broader definitions of terms. If any of such incorporated disclosures conflict in whole or in part with each other, then the later-date disclosure shall prevail as to the extent of the conflict.

[0073] Abstracts are provided as needed to assist those searching for specific topics within the patent literature. However, these abstracts are not intended to imply that any particular claim necessarily covers any element, feature, or limitation listed therein. The scope of the subject matter covered by each claim should be determined solely by the enumeration of that claim.

Claims

1. A luminescent material comprising a material having the general chemical formula AE y-x Li 10-2y P4N 10 Eu x Nitrogen phosphate materials, wherein (i) AE includes one or more of Ca, Sr or Ba, and (ii) y ≥ x > 0.

2. The luminescent material according to claim 1, wherein y = 2 and 0.1 > x > 0.

3. The luminescent material according to claim 2, wherein AE comprises only Ca.

4. The luminescent material according to claim 2, wherein AE comprises a majority amount of Ca and a smaller amount of Sr or Ba.

5. The luminescent material according to claim 2, wherein the luminescent material exhibits a peak emission wavelength greater than 600 nm.

6. A method for preparing the luminescent material according to claim 1, the method comprising, at an isostatic nitrogen pressure of 50 MPa to 200 MPa and a temperature of 800 °C to 1000 °C, reacting (i)Li 10 P4N 10 (ii) A mixture of halides, hydrides, azides or nitrides of AE and (iii) halides or oxides of Eu performs solid-state reactions.

7. The method according to claim 6, further comprising washing the luminescent material to remove LiCl formed by the solid-state reaction.

8. A method for preparing the luminescent material according to claim 1, the method comprising performing a solid-state reaction on a mixture of (i) AE2PN3:Eu, (ii) LiPN2 and (iii) Li3N at an isostatic nitrogen pressure of 50 MPa to 200 MPa and a temperature of 800 °C to 1000 °C.

9. A wavelength conversion structure comprising a structure having the universal chemical formula AE y-x Li 10-2y P4N 10 Eu x Nitrogen phosphate luminescent materials, wherein (i) AE includes one or more of Ca, Sr or Ba, and (ii) y ≥ x > 0.

10. A method for preparing the wavelength conversion structure according to claim 9, the method comprising bonding particles of the nitrogen phosphate luminescent material together in a polymer or ceramic binder material.

11. The method of claim 10, further comprising forming a particulate coating on the particles of the nitrogen phosphate luminescent material before bonding the particles together.

12. A method for preparing the wavelength conversion structure according to claim 9, the method comprising (i) mixing particles of the nitrogen phosphate luminescent material with particles of one or more additional luminescent materials, and (ii) bonding the particles of the nitrogen phosphate luminescent material and the particles of the one or more additional luminescent materials together in a polymer or ceramic binder.

13. A light-emitting device comprising a group III nitride light-emitting diode (LED) and a wavelength conversion structure according to claim 9, wherein the LED is arranged to emit light of a first wavelength that is at least partially absorbed by the light-emitting material, the nitride light-emitting material exhibiting emission of light of a second wavelength caused by absorption of the first wavelength, the second wavelength being longer than the first wavelength.

14. The wavelength conversion structure according to claim 9, wherein y = 2 and 0.1 > x > 0.

15. The wavelength conversion structure according to claim 14, wherein AE comprises only Ca.

16. The wavelength conversion structure according to claim 14, wherein AE comprises a majority amount of Ca and a smaller amount of Sr or Ba.

17. The wavelength conversion structure according to claim 14, wherein the nitrogen phosphate luminescent material exhibits a peak emission wavelength greater than 600 nm.

18. A light-emitting device comprising a group III nitride light-emitting diode (LED) and a wavelength conversion structure according to claim 17, wherein the LED is arranged to emit light of a first wavelength less than 500 nm, the light being at least partially absorbed by a nitrogen-phosphate luminescent material of the wavelength conversion structure, the nitrogen-phosphate luminescent material exhibiting emission of light of a second wavelength greater than 600 nm, the emission being caused by the absorption of the first wavelength light.

19. A method for operating a light-emitting device according to claim 18, the method comprising supplying a current to the LED such that (i) the LED emits light of a first wavelength, and (ii) absorption of at least a portion of the first wavelength light by the nitrophosphate light-emitting material of the wavelength conversion structure results in the emission of light of a second wavelength, the second wavelength light being included in the output light of the light-emitting device.

20. The method of claim 19, wherein the light of the first wavelength is absent or only negligibly present in the output light of the light-emitting device.

21. The method of claim 19, wherein a portion of the light of the first wavelength is included in the output light of the light-emitting device.

22. The method of claim 19, wherein the wavelength conversion structure comprises one or more additional light-emitting materials, the absorption of at least a portion of light of the first wavelength by each of the one or more additional light-emitting materials of the wavelength conversion structure resulting in the emission of light of a corresponding additional wavelength longer than the first wavelength, and the output light of the light-emitting device comprises light emitted by the one or more additional light-emitting materials of the wavelength conversion structure.

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