Description:FIELD OF THE INVENTION
[001] The present invention relates to the field of healthcare, sports, and communication, and more particularly, the present invention relates to the highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability that is used for pure red and white colour LED lights. It makes the colours look more natural, like seeing a painting or clothes in real life, where every colour appears as it should. The best part of this material is its thermal stability i.e. it will not degrade with continuous and prolonged use. This makes it perfect for places like homes, shops, or offices where lights are used for a long time and need to show clear, true colours.
BACKGROUND FOR THE INVENTION:
[002] The following discussion of the background of the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known, or part of the common general knowledge in any jurisdiction as of the priority date of the application. The details provided herein the background if belongs to any publication is taken only as a reference for describing the problems, in general terminologies or principles or both of science and technology in the associated prior art.
[003] Extensive advancements have been made in the field of solid-state lighting, particularly in the development of red LEDs and white LEDs. However, despite this technological progress, several critical issues continue to hinder their performance. One of the most prominent challenges is the insufficient red colour purity, which results in a high correlated colour temperature (CCT), thus limiting the overall colour rendering capabilities of white LEDs. Furthermore, the thermal stability of these devices is often compromised, especially at elevated temperatures, leading to degradation in both performance and longevity. Many Europium-doped phosphors have been commercially used as red phosphor material in white LEDs due to their efficient red emission in the visible region. Despite their widespread adoption, these materials fall short of delivering the required red colour purity and thermal stability for high-performance lighting applications. For example, although Europium-doped Y2O3 is effective in producing red light, it often fails to achieve the high standards required for red colour purity, correlated colour temperature (CCT) and precise thermal stability. These limitations lead to less accurate colour rendering and less thermal stability, which diminishes the overall quality and consistency of the white light produced.
[004] Following is some of the closest relevant prior arts:
S. No. Patent ID Title of Patent Date Of Patent Patent Authority
1

2

3

4 US2015123155A1

US20100308712A1

JP2016156022 A

US7931826B2 Phosphors, such as New Narrow-band Red Emitting Phosphors for Solid State Lighting
Nitride-Based Red-Emitting Phosphors in RGB Red-Green-Blue Lighting Systems
Red Phosphor, Production Method of Red Phosphor, White Light Source, Illuminating Device, and Liquid Crystal Display Device
White Light Illumination Device
May, 07, 2015

Dec, 09, 2010

Sep, 01, 2016

April, 26, 2011 US Patent

US Patent

Japan Patent

US Patent

[005] In light of the foregoing, there is a need for the Highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability that overcomes problems prevalent in the prior art.
OBJECTS OF THE INVENTION:
[006] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
[007] The principal object of the present invention is to overcome the disadvantages of the prior art by providing the Highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability.
[008] Another object of the present invention is to provide a highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability that enhances red colour purity, which reduces CCT and improves colour rendering.
[009] Another object of the present invention is to provide a highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability, wherein the incorporations of CaO and ZnO significantly increase the thermal stability of the phosphor, allowing it to maintain its luminescent properties even under high-temperature conditions.
[010] Another object of the present invention is to provide a highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability, that provides an efficient, and thermally stable solution for improving the performance of white LEDs, addressing the long-standing issues in the industry with an approach that is both practical and effective for next-generation lighting systems.
[011] Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY OF THE INVENTION:
[012] The present invention provides a highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability.
[013] In one aspect of the present invention, the uniqueness of this invention is the creation of a new phosphor material that makes LED lights better. This material makes the colours brighter and more natural compared to regular LED lights. It works well even when the LEDs get hot while regular LEDs can dim or change colour when heated up. For example, in places like stores, this invention makes sure that clothes or fresh fruits keep looking their real colours, even when they are exposed to LED lights for a long time. This improvement builds on existing LED technology by fixing common issues, making our invention stand out for providing better, more reliable lighting in everyday settings.
[014] In another aspect of the present invention, the invention pertains to the development of a novel nanocomposite phosphor material synthesized using a cost-effective, single-step sol-gel Pechini method, with citric acid acting as a complexing agent. Initially, precursor salts are dissolved in deionized (DI) water under continuous stirring to ensure uniform dispersion. Following complete dissolution, the solution is heated at 80°C to induce gelation. Once gelation occurs, the temperature is increased to initiate an auto-combustion process. Subsequently material then quickly transforms into a brown sponge called “xerogel”. The xerogel is grinded into a fine powder using a mortar and pestle. The powdered material is then sintered in a high-temperature tubular furnace, with a stay time of 3 hours. This approach yields a nanocomposite phosphor material with enhanced properties, suitable for applications in advanced solid-state lighting.
[015] A nanocomposite phosphor material (Cao/Y2(1-x)Eu2xO3/ZnO) (x = 0 to 10 mol.%) doped with Europium (Eu³?) prepared by a single-step method (sol-gel Pechini method) wherein the composition enhances red colour purity, reduces correlated colour temperature (CCT) and improves thermal stability for use in solid-state lighting applications.
[016] The nanocomposite material of Claim in [015], maintains its luminescent efficiency at temperatures up to 190°C (463 K), thereby providing improved thermal stability in high-performance LED and white LED applications.
[017] An LED device incorporating the nanocomposite material of Claim in [015], wherein the material is used as a phosphor to enhance red light emission, improve colour purity, and reduce the CCT of the device.
[018] A white LED lighting system comprising the nanocomposite material of Claim in [015], wherein the material is employed to achieve a thermally stable and high-quality white light output with improved red colour accuracy and reduced CCT.
BRIEF DESCRIPTION OF DRAWINGS:
[019] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
[020] Fig. 1 Photoluminescence emission spectra of CaO/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%) denoted by (CYZ) and Y2(1-x)Eu2xO3 (x = 5 mol.%) denoted by (YO) at excitation wavelength 244 nm
[021] Fig. 2 CIE-1931 chromaticity diagram of Y2(1-x)Eu2xO3 (x = 5 mol.%) and CaO/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%)
[022] Fig. 3 Temperature-dependent photoluminescence emission spectra at 532 nm leaser (used as excitation source) for (a) Y2(1-x)Eu2xO3 (x = 5 mol.%) and (b) CaO/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%)
DETAILED DESCRIPTION OF DRAWINGS:
[023] While the present invention is described herein by way of example using embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments of drawing or drawings described and is not intended to represent the scale of the various components. Further, some components that may form a part of the invention may not be illustrated in certain figures, for ease of illustration, and such omissions do not limit the embodiments outlined in any way. It should be understood that the drawings and the detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claim.
[024] As used throughout this description, the word “may” is used in a permissive sense (i.e. meaning having the potential to), rather than the mandatory sense, (i.e. meaning must). Further, the words “a” or “an” mean “at least one” and the word “plurality” means “one or more” unless otherwise mentioned. Furthermore, the terminology and phraseology used herein are solely used for descriptive purposes and should not be construed as limiting in scope. Language such as “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers, or steps. Likewise, the term “comprising” is considered synonymous with the terms “including” or “containing” for applicable legal purposes. Any discussion of documents, acts, materials, devices, articles, and the like are included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention.
[025] In this disclosure, whenever a composition or an element or a group of elements is preceded with the transitional phrase “comprising”, it is understood that we also contemplate the same composition, element, or group of elements with transitional phrases “consisting of”, “consisting”, “selected from the group of consisting of, “including”, or “is” preceding the recitation of the composition, element or group of elements and vice versa.
[026] The present invention is described hereinafter by various embodiments with reference to the accompanying drawing, wherein reference numerals used in the accompanying drawing correspond to the like elements throughout the description. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the following detailed description, numeric values and ranges are provided for various aspects of the implementations described. These values and ranges are to be treated as examples only and are not intended to limit the scope of the claims. In addition, several materials are identified as suitable for various facets of the implementations. These materials are to be treated as exemplary and are not intended to limit the scope of the invention.
[027] The present invention provides a highly pure red color emitting Eu3+-doped ternary nanocomposite with enhanced luminescence and thermal stability. The invention pertains to the development of a novel nanocomposite phosphor material synthesized using a cost-effective, single-step sol-gel Pechini method, with citric acid acting as a complexing agent. Initially, precursor salts are dissolved in deionized (DI) water under continuous stirring to ensure uniform dispersion. Following complete dissolution, the solution is heated at 80°C to induce gelation. Once gelation occurs, the temperature is increased to initiate an auto-combustion process. Subsequently material then quickly transforms into a brown sponge called “xerogel”. The xerogel is grinded into a fine powder using a mortar and pestle. The powdered material is then sintered in a high-temperature tubular furnace, with a stay time of 3 hours. This approach yields a nanocomposite phosphor material with enhanced properties, suitable for applications in advanced solid-state lighting.
[028] In the photoluminescence (PL) emission spectra, the peak at 612 nm (red region) exhibits the highest intensity when excited at a wavelength of 244 nm. The photoluminescence emission intensity of nanocomposite phosphor CaO/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%) (CYZ:Eu5%)] is five times enhanced as compared to Y2(1-x)Eu2xO3 (x = 5 mol.%) (YO:Eu5%) as presented in Fig. 1.
[029] The CIE chromaticity coordinates (x, y) are calculated using the CIE 1931 colour chromaticity diagram. At x = 5 mol% (optimized concentration) concentration of Eu3+ in nanocomposite (CYZ), the CIE coordinates are approximately (0.65, 0.34), which are close to the ideal red colour coordinates of (0.67, 0.33) established by the National Television Standards Committee (NTSC). The CIE coordinates for Y2(1-x)Eu2xO3 (x = 5 mol.%) is (0.63, 0.36) and CaO/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%), as shown in Fig. 2 and listed in Table 1. This plot indicates a shift from red for Y2O3 to a deeper red region for the nanocomposite (CYZ), with an improvement in colour purity from 95% for Y2O3 to 99% for nanocomposite (CYZ).
Table 1 Comparison of CIE coordinates, colour purity, and activation energy ( ?E) of invented nanocomposite [CaO/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%)] with commercial nanophosphor [Y2(1-x)Eu2xO3 (x = 5 mol.%)]
Sample CIE coordinates Colour Purity ?E
CYZ:Eu3+
YO:Eu3+ 0.64998, 0.34362
0.63126, 0.36625 99.17%
95.23% 2.4 eV
0.48 eV

[030] The nanocomposite material exhibits superior thermal stability, maintaining its structural integrity and luminescent properties up to 190°C (463 K), which is markedly higher than that of Y2O3:Eu3+ [130°C (403 K)]. This enhanced thermal performance, as clearly depicted in Fig. 3, additionally calculated activation energy (?E) (mentioned in Table 1) of nanocomposite [Cao/Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%)] which is 2.4 eV higher than that of Y2(1-x)Eu2xO3/ZnO (x = 5 mol.%) (0.48 eV) underscores the nanocomposite potential for applications in high-temperature environments, making it more suitable for advanced solid-state lighting systems and other thermally demanding technologies.
[031] The current invention presents several distinct advantages over existing technologies, particularly when compared to Y2O3 phosphors:
- Enhanced Red Colour Purity: The nanocomposite material of the invention significantly improves red colour purity compared to traditional Y2O3 phosphors. This enhancement ensures a more vivid and accurate red emission, leading to superior colour rendering in white LEDs.
- Superior Thermal Stability: The incorporation of CaO and ZnO into the nanocomposite enhances its thermal stability and maintains its luminescence efficiency up to high temperatures.
- Increased Luminescent Efficiency: The innovative composition of the nanocomposite material results in higher luminescent efficiency compared to Y2O3 This efficiency is maintained across a wider range of operating temperatures, contributing to the overall effectiveness and longevity of the LEDs.
[032] Practical Integration: The nanocomposite material can be seamlessly integrated into existing manufacturing processes, offering a practical and scalable solution for improving white LED performance without requiring significant changes to current production methods.
[033] The invented novel material may be used as a product in the following fields:
- Solid-state lighting such as LEDs and white LEDs
- Optoelectronic devices such as Sensors and optical instruments
- Latent fingerprints (LFPs) identification inks and anticounterfeiting inks
- Biomedical field in biosensors, bioimaging, drugs, etc.
[034] The disclosure has been described with reference to the accompanying embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
[035] The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.
, Claims:1) A nanocomposite material, the nanocomposite material comprises a phosphor material (Cao/Y2(1-x)Eu2xO3/ZnO) (x = 0 to 10 mol.%) doped with Europium (Eu3+).
2) A method for preparing a red color emitting Eu3+-doped ternary nanocomposite, the method comprises a single-step sol-gel Pechini method;
- dissolving precursor salts in deionized (DI) water under continuous stirring;
- heating the completely dissolved solution at 80°C to induce gelation;
- once gelation occurs, increasing the temperature to initiate an auto-combustion process; wherein the material then quickly transforms into a brown sponge called “xerogel”;
- gridding the xerogel into a fine powder using a mortar and pestle; and
- sintering the powdered material in a high-temperature tubular furnace, with a stay time of 3 hours;
- wherein the nanocomposite phosphor material (Cao/Y2(1-x)Eu2xO3/ZnO) (x = 0 to 10 mol.%) is doped with Europium (Eu3+).
3) The method as claimed in claim 2, wherein citric acid acting as a complexing agent.