Eu(ii)-based halides with narrow-band emission, methods of making and light emitting devices

Abstract

The application belongs to the technical field of luminescent materials, and discloses Eu(II) based halides with narrow-band emission, a preparation method thereof and a luminescent device. u Eu(II) v X w The application proposes that the uniformly mixed raw materials are sintered through a vacuum sintering process at 10 ‑2 -10 ‑5 Pa vacuum degree and a sintering temperature of 120-380 DEG C, and a sintering time of 2-24h. The material exhibits the characteristics of high luminous intensity, small half-width, good temperature quenching characteristics, wide excitation range and the like. The application solves the key problems of high energy consumption and poor thermal stability of the current narrow-band fluorescent powder high-temperature sintering.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials, and more specifically to Eu(II)-based halides with narrowband emission, their preparation methods, and luminescent devices. Background Technology

[0002] In recent years, narrowband LEDs, as a new type of solid-state light source, have been widely used in the display field due to their advantages such as being green, environmentally friendly, and having a long lifespan. In the LED display process, the performance of the phosphor (luminous intensity, color coordinates, peak wavelength, and full width at half maximum) directly determines the color gamut of the display. Therefore, the luminous performance of the phosphor directly affects and determines the display performance of the LED. Currently, the phosphors used in display LEDs mainly belong to four major systems: aluminate, silicate, nitride / oxygen nitride, and fluoride. Among them, the green phosphors used in low-to-mid-range LCD displays are mainly silicate phosphors, while the green phosphors used in high-end displays are mainly β-sialon:Eu oxynitride. These materials have high synthesis temperatures, complex processes, and high energy consumption; furthermore, these materials are difficult to nanoscale, for example, their fluorescence efficiency decreases sharply with decreasing grain size, making it difficult to meet the requirements of next-generation display technologies (Mini / Micro-LED).

[0003] Micro-LEDs have attracted immense interest in display technology due to their high brightness, contrast, resolution, and lifespan. The commercialization of micro-LEDs has achieved unprecedented success over the past decade, exemplified by 55-inch displays (Sony in 2012) and the 146-inch "The Wall" TV (Samsung in 2018). Color conversion materials, which couple red and green emission layers onto blue LED chips, are one of the best solutions for achieving full-color displays. Among these, color conversion materials with narrow-band emission play a crucial role in expanding the color gamut. Current color conversion materials typically focus on rare-earth phosphors, quantum dots (QDs), or metal halide perovskites (MHPs). Rare-earth phosphors possess high quantum yields, excellent thermal stability, and chemical stability; however, their micron-sized particles prevent uniform coating on micro-LED pixels, affecting the efficiency and uniformity of full-color displays. While rapidly developing quantum dots and MHPs offer advantages such as nanoscale size, narrow emission, and high luminous efficiency, their low stability often leads to performance degradation and pattern incompatibility in micro-LED displays. Another key issue with QDs and MHPs is Cd / Pb toxicity, which has raised significant concerns about health and the environment.

[0004] Therefore, next-generation display technologies place new demands on color conversion materials, including narrow emission linewidth, environmental friendliness, high quantum yield, and thermal stability. A key objective of this research is to discover novel narrow-band green emitters and provide an innovative approach for designing such color conversion materials for display technologies. Inspired by Eu(II)-based inorganic phosphors, attention can be turned to using Eu(II) ions to replace B-site Pb(II) in Pb-based MHPs. Typically, Eu-based... 2+ Phonon frequencies in halides (~200 cm⁻¹) -1 ) much lower than oxides and nitrides (~600cm) -1 Lead (Eu(II)) contributes to narrow emission linewidths (~25 nm). Therefore, designing and exploring narrowband green emitters in Eu(II)-based MHP remains challenging. Next-generation narrowband emitting Pb-based perovskite materials have attracted widespread research and application interest, but the use of lead can cause environmental problems and harm to human health; therefore, the development of novel environmentally friendly lead-free narrowband emitting fluorescent materials is both necessary and urgent. Summary of the Invention

[0005] One of the objectives of this invention is to provide a narrowband green phosphor for display devices that has high luminous intensity, high color purity, small half-width, good temperature quenching characteristics, and a wide excitation range.

[0006] The second objective of this invention is to provide a novel narrow-band emission phosphor prepared by low-temperature sintering or solution.

[0007] The third objective of this invention is to provide a white LED light-emitting device with a large color gamut, good color temperature uniformity, and low light decay.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] Eu(II)-based halides with narrowband emission, their preparation method, and luminescent device, characterized in that the chemical formula of the hybrid metal halide is, Or u Eu(II) v X w Where Or is an organic ligand such as tetraphenylphosphine, triphenylphosphine, benzyltrimethyl halide, benzyltrimethyl halide, benzyltriethyl halide, benzyltributyl halide, 1-methyl-1-ethylpyrrolidine bromide, tetramethylamine, tetraethylamine, tetrapropylamine, tetrabutylamine, tetrapentylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, etc.; 1≤u≤15, 1≤v≤10, 3≤w≤30; X is one or more of Cl, Br, and I.

[0010] On the other hand, the present invention provides a method for preparing the narrowband green phosphor for display devices as described above. The preparation method is as follows: (1) europium halide and organic ligand are ground and mixed evenly in a molar ratio of v:u; (2) the mixed powder is added into a glass tube in a glove box and vacuum-sealed, with the vacuum degree controlled at 10. -2 -10 -5 Pa; (3) The glass tube is sintered at a low temperature of 120-380℃ for 2-24 hours.

[0011] A white LED light-emitting device includes a packaging substrate, a blue LED chip, and two phosphors capable of effectively absorbing the light emitted by the LED chip and emitting red and green light; the green phosphor has the chemical formula Or. u Eu(II) v X w Narrow-band green phosphor used in display devices.

[0012] The blue LED chip is an InGaN semiconductor chip with a peak emission wavelength of 455nm. The narrowband red phosphor is K2SiF6:Mn. 4+ .

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1) The narrowband green phosphor used in the display device of this invention is a low-dimensional metal halide, which achieves efficient photoluminescence and good temperature stability. It can be assembled with blue light chips and narrowband red phosphors to form a wide color gamut liquid crystal display LED device, which can meet the needs of the industry to a large extent.

[0015] 2) The preparation method of the present invention is simple, easy to operate, has low equipment cost and is pollution-free; it can generate huge social and economic benefits and is suitable for widespread use.

[0016] 3) The narrowband green phosphor used in this invention for display devices, combined with the narrowband red phosphor in the prior art, can obtain a series of high-efficiency white lights under blue light excitation, which can meet the needs of the liquid crystal display field. At the same time, it has the advantages of wide color gamut, good color temperature uniformity and low light decay. Attached Figure Description

[0017] Figure 1 The crystal structure of the narrowband phosphor prepared in Example 1;

[0018] Figure 2 XRD pattern of the narrowband phosphor prepared in Example 1;

[0019] Figure 3 The excitation and emission spectra of the narrowband phosphor prepared in Example 1 are shown.

[0020] Figure 4 The excitation and emission spectra of the narrowband phosphor prepared in Example 2 are shown.

[0021] Figure 5 The excitation and emission spectra of the narrowband phosphor prepared in Example 3 are shown.

[0022] Figure 6 The excitation and emission spectra of the narrowband phosphor prepared in Example 4 are shown.

[0023] Figure 7 The excitation and emission spectra of the narrowband phosphor prepared in Example 5 are shown.

[0024] Figure 8 The excitation and emission spectra of the narrowband phosphor prepared in Example 6 are shown.

[0025] Figure 9 The excitation and emission spectra of the narrowband phosphor prepared in Example 7 are shown.

[0026] Figure 10 The excitation and emission spectra of the narrowband phosphor prepared in Example 8 are shown.

[0027] Figure 11 The excitation and emission spectra of the narrowband phosphor prepared in Example 9 are shown.

[0028] Figure 12 The excitation and emission spectra of the narrowband phosphor prepared in Example 10 are shown. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications to the invention by those skilled in the art in various equivalent forms will fall within the scope defined by the appended claims.

[0030] Example 1

[0031] A certain amount of sample was weighed according to the molar ratio of tetraethylammonium iodide and EuI2 of 2:1 in an argon-filled glove box (to prevent the oxidation of EuI2). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 200℃ for 12 hours, and then removed after natural cooling. Its crystal structure is shown below. Figure 1 As shown, XRD Figure 2 As shown, the excitation (520nm monitoring) and emission spectra (450nm excitation) are shown in [reference needed]. Figure 3As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 520 nm, and its full width at half maximum (FWHM) is 45 nm.

[0032] Example 2

[0033] Based on a 2:1 molar ratio of tetramethylammonium iodide and EuI2, certain amounts of samples were weighed and thoroughly mixed in an argon-filled glove box (to prevent oxidation of EuI2). The mixtures were then transferred to quartz or glass tubes and vacuum-sealed, with the vacuum level controlled at 10 °C. -5 Pa; The glass tube was sintered at a low temperature of 250℃ for 12 hours, and then removed after natural cooling. Excitation (530nm monitoring) and emission spectra (450nm excitation) are shown in [reference needed]. Figure 3 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength covers 500–600 nm, its peak wavelength is at 530 nm, and its full width at half maximum (FWHM) is 53 nm.

[0034] Example 3

[0035] A certain amount of sample was weighed according to the 1:1 molar ratio of tetrapropylammonium iodide and EuI2 in an argon-filled glove box (to prevent the EuI2 from being oxidized). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 180℃ for 12 hours, and then removed after natural cooling. Excitation (520nm monitoring) and emission spectra (450nm excitation) are shown below. Figure 5 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 520 nm, and its full width at half maximum (FWHM) is 42 nm.

[0036] Example 4

[0037] A certain amount of sample was weighed according to the molar ratio of tetramethylammonium bromide and EuBr2 of 2:1 in an argon-filled glove box (to prevent the oxidation of EuBr2). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 180℃ for 14 hours, and then removed after natural cooling. Excitation (515nm monitoring) and emission spectra (450nm excitation) are shown below. Figure 6 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 525 nm, and its full width at half maximum (FWHM) is 64 nm.

[0038] Example 5

[0039] A certain amount of sample was weighed according to the molar ratio of tetraethylammonium bromide and EuBr2 (3:1) in an argon-filled glove box (to prevent oxidation of EuBr2). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 280℃ for 10 hours, and then removed after natural cooling. Excitation (515nm monitoring) and emission spectra (450nm excitation) are shown below. Figure 7 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 515 nm, and its full width at half maximum (FWHM) is 55 nm.

[0040] Example 6

[0041] A certain amount of sample was weighed out according to the 1:1 molar ratio of tetrapropylammonium bromide and EuBr2 in an argon-filled glove box (to prevent the EuBr2 from being oxidized). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 220℃ for 9 hours, and then removed after natural cooling. Excitation (500nm monitoring) and emission spectra (450nm excitation) are shown in [reference needed]. Figure 8 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 500 nm, and its full width at half maximum (FWHM) is 48 nm.

[0042] Example 7

[0043] A certain amount of sample was weighed according to the molar ratio of tetraethylammonium chloride and EuCl2 (1:1) in an argon-filled glove box (to prevent oxidation of EuCl2). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 200℃ for 10 hours, and then removed after natural cooling. Excitation (monitored at 490nm) and emission spectra (excitation at 450nm) are shown in [reference needed]. Figure 9 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength covers 500–600 nm, its peak wavelength is at 490 nm, and its full width at half maximum (FWHM) is 46 nm.

[0044] Example 8

[0045] According to the molar ratio of ethyltripropylammonium bromide and EuBr2 (3:1), a certain amount of sample was weighed in an argon-filled glove box (to prevent EuBr2 from being oxidized), thoroughly mixed, and then transferred to a quartz tube or glass tube. The tube was then vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 240℃ for 14 hours, and then removed after natural cooling. Excitation (monitored at 490nm) and emission spectra (excitation at 410nm) are shown below. Figure 10 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 490 nm, and its full width at half maximum (FWHM) is 36 nm.

[0046] Example 9

[0047] According to the molar ratio of ammonium bromide and EuBr2 (3:1), a certain amount of sample was weighed in an argon-filled glove box (to prevent EuBr2 from being oxidized), thoroughly mixed, and then transferred to a quartz tube or glass tube. The tube was then vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 240℃ for 14 hours, and then removed after natural cooling. Excitation (monitored at 435nm) and emission spectra (excitation at 320nm) are shown below. Figure 11 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 435 nm, and its full width at half maximum (FWHM) is 27 nm.

[0048] Example 10

[0049] A certain amount of sample was weighed according to the molar ratio of trimethylammonium bromide and EuBr2 of 2:1 in an argon-filled glove box (to prevent the oxidation of EuBr2). After thorough mixing, the sample was transferred to a quartz tube or glass tube and vacuum-sealed, with the vacuum level controlled at 10. -5 Pa; The glass tube was sintered at a low temperature of 220℃ for 10 hours, and then removed after natural cooling. Excitation (540nm monitoring) and emission spectra (450nm excitation) are shown in [reference needed]. Figure 12 As shown, its excitation wavelength range covers 300–500 nm, its emission wavelength ranges 500–600 nm, its peak wavelength is at 540 nm, and its full width at half maximum (FWHM) is 53 nm.

[0050] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An Eu(II)-based halide with narrowband emission, characterized in that, The chemical formula of the hybrid metal halide is Or u Eu(II) v X w Wherein, Or is an organic ligand selected from tetraphenylphosphonium, triphenylphosphonium, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetrapentylammonium, dimethylammonium, diethylammonium, dipropylammonium, dibutylammonium, or dipentylammonium; X is one or more of Cl, Br, and I; and 1≤u≤15, 1≤v≤10, 3≤w≤30.

2. The Eu(II)-based halide with narrowband emission according to claim 1, characterized in that, The organic ligand Or is tetraethylammonium, tetramethylammonium, tetrapropylammonium, or tetraethylammonium.

3. A method for preparing the Eu(II)-based halide with narrowband emission as described in claim 1, characterized in that, The process includes the following steps: (1) grinding and mixing europium halide and organic ligand in a molar ratio of v:u; (2) adding the mixed powder into a glass tube in a glove box and sealing the tube under vacuum; (3) sintering the glass tube at a low temperature of 120-380℃ for 2-24 h to obtain Eu(II)-based halides with narrow-band emission.

4. The preparation method according to claim 3, characterized in that, In step (2), the vacuum degree of the vacuum-sealed tube is controlled at 10 -2 -10 -5 Pa.

5. A white LED light-emitting device, comprising a packaging substrate, a blue LED chip, and two phosphors capable of effectively absorbing the light emitted by the LED chip and emitting red and green light; characterized in that, The green phosphor is the Eu(II)-based halide with narrowband emission as described in claim 1; the blue LED chip is an InGaN semiconductor chip with a peak emission wavelength of 455 nm; the red phosphor is K2SiF6:Mn. 4+ .

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