A lead-based halide capable of emitting blue light, and a preparation method and applications thereof

Abstract

The application discloses a lead-based halide capable of emitting blue light and a preparation method and application thereof, and relates to the field of luminescent materials. b ) n (X c ) 4‑n , wherein A includes a quaternary ammonium salt type cation containing benzyl and tripropyl, X b includes Cl ‑ or Br ‑ , X c includes any one of Cl ‑ , Br ‑ and I ‑ , and is different from X b , and n is an integer between 1 and 4. The lead-based halide is a triplet state self-trapped exciton (STE) luminescence, has high luminescent efficiency, an emission wavelength of 420-480 nm, and an emission peak half-peak width less than 50 nm, and has the advantages of high luminescent efficiency and narrow-band blue light emission.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials, and in particular to a lead-based halide that emits blue light, its preparation method, and its applications. Background Technology

[0002] With societal development, the demand for monochromatic light-emitting materials emitting red, green, and blue primary colors is increasing. However, the efficiency and stability of blue light, especially saturated deep blue light, currently lag far behind those of red and green. A narrow half-width at half-maximum (HWHM) ensures high color purity in fluorescent materials; higher color purity results in a wider color gamut and is more conducive to reducing LED power consumption. Existing high-efficiency narrowband blue light-emitting materials are mainly achieved through all-inorganic halide materials, which have poor structural stability and require high excitation energy. Developing high-efficiency narrowband blue light-emitting materials remains a challenge.

[0003] Existing blue light emitting materials suffer from low luminous efficiency, wide half-width, and impure blue light color purity. Summary of the Invention

[0004] The main objective of this invention is to propose a lead-based halide that can emit blue light, its preparation method, and its application, aiming to solve the problems of low luminous efficiency, wide half-width, and impure blue light purity in the prior art.

[0005] To achieve the above objectives, this invention proposes a lead-based halide capable of emitting blue light, wherein the general chemical formula of the lead-based halide capable of emitting blue light is A₂Pb(X). b )n(X c ) 4-n ,in:

[0006] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0007] X b Including Cl - or Br - ;

[0008] X c Including Cl - ,Br - and I - Any one of them, and with X b different;

[0009] The value of n is an integer between 1 and 4.

[0010] This invention also provides a method for preparing a lead-based halide that emits blue light, the method comprising the following steps:

[0011] An ammonium halide compound containing benzyl and tripropyl groups, a lead halide, and an organic solvent are mixed to obtain a mixture.

[0012] The diffusing agent is diffused into the mixture, precipitating a blue light-emitting lead-based halide. The general chemical formula of the blue light-emitting lead-based halide is A₂Pb(X₂)₃. b )n(X c ) 4-n ,in:

[0013] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0014] X b Including Cl - or Br - ;

[0015] X c Including Cl - ,Br - and I - Any one of them, and with X b different;

[0016] The value of n is an integer between 1 and 4.

[0017] Optionally, in the method for preparing the blue light-emitting lead-based halide, the molar ratio of the ammonium halide compound containing benzyl and tripropyl to the lead halide is (1.5-2.5):1.

[0018] Optionally, in the method for preparing the blue light-emitting lead-based halide, the ammonium halide compound containing benzyl and tripropyl groups includes at least one of benzyltripropylammonium chloride, benzyltripropylammonium bromide, and benzyltripropylammonium iodide.

[0019] Optionally, in the method for preparing the blue light-emitting lead-based halide, the lead halide includes at least one of PbCl2, PbBr2, and PbI2.

[0020] Optionally, in the method for preparing the blue light-emitting lead-based halide, the organic solvent includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEF), and dimethyl sulfoxide (DMSO).

[0021] Optionally, the dispersant includes at least one of diethyl ether, acetonitrile, acetone, and chloroform.

[0022] This invention also provides a white LED, including a blue LED chip, wherein the blue LED chip comprises the lead-based halide capable of emitting blue light, or a lead-based halide capable of emitting blue light prepared by a method comprising the preparation of the lead-based halide capable of emitting blue light. The general chemical formula of the lead-based halide capable of emitting blue light is A2Pb(X). b )n(Xc ) 4-n ,in:

[0023] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0024] X b Including Cl - or Br - ;

[0025] X c Including Cl - ,Br - and I - Any one of them, and with X b different;

[0026] The value of n is an integer between 1 and 4.

[0027] This invention also provides an LED display backlight module, comprising an LED backlight material, wherein the LED backlight material comprises the blue-light-emitting lead-based halide, or a blue-light-emitting lead-based halide prepared by a method comprising the preparation method of the blue-light-emitting lead-based halide. The general chemical formula of the blue-light-emitting lead-based halide is A2Pb(X) b )n(X c ) 4-n ,in:

[0028] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0029] X b Including Cl - or Br - ;

[0030] X c Including Cl - ,Br - and I - Any one of them, and with X b different;

[0031] The value of n is an integer between 1 and 4.

[0032] The present invention also provides an X-ray detector, comprising a scintillator material, wherein the scintillator material comprises the aforementioned blue-light-emitting lead-based halide, or a blue-light-emitting lead-based halide prepared by a method comprising the aforementioned blue-light-emitting lead-based halide. The general chemical formula of the blue-light-emitting lead-based halide is A₂Pb(X-rays)₂. b ) n (X c ) 4-n ,in:

[0033] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0034] X b Including Cl - or Br - ;

[0035] X c Including Cl - ,Br - and I - Any one of them, and with X b different;

[0036] The value of n is an integer between 1 and 4.

[0037] The beneficial effects of this invention are as follows:

[0038] (1) The synthesized zero-dimensional organic-inorganic hybrid lead-based halide has an inorganic structural unit [Pb(X b ) n (X c ) 4-n ] 2- (X b =Cl - ,Br - ;X c =Cl - ,Br - I - (n takes the value of an integer between 1 and 4), under normal pressure, it emits light as a triplet self-trapped exciton (STE). Due to the band gap energy of the material, organic-inorganic hybrid lead-based zero-dimensional halides usually exhibit blue light.

[0039] (2) Quaternary ammonium salt-type organic cations containing benzyl and tripropyl groups are used. These cations are both rigid and flexible, and their molecular volume is sufficient to separate the inorganic metal luminescent centers, ensuring appropriate spacing between them. Furthermore, the formation of stable hydrogen bonds reduces energy loss from non-radiative vibrations, thereby improving luminescence efficiency and reducing the half-width at half-maximum (WHM) of the emission peak. Therefore, the resulting zero-dimensional lead-based halide exhibits high luminescence efficiency, a WHM of less than 50 nm, narrow emission peak width, and high color purity. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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 the structures shown in these drawings without creative effort.

[0041] Figure 1These are single-crystal diffraction structure diagrams of blue light-emitting lead-based halides from Examples 1-3 of this invention.

[0042] Figure 2 Comparison of powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction (SCXRD) spectra of the blue light-emitting lead-based halide in Example 1 of the present invention;

[0043] Figure 3 Comparison of powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction (SCXRD) patterns of the blue light-emitting lead-based halide in Example 2 of the present invention;

[0044] Figure 4 Comparison of powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction (SCXRD) spectra of the blue light-emitting lead-based halide in Example 3 of the present invention;

[0045] Figure 5 This is the fluorescence emission spectrum of a lead-based halide that emits blue light according to Example 1 of the present invention;

[0046] Figure 6 This is the fluorescence emission spectrum of a lead-based halide that emits blue light according to Example 2 of the present invention;

[0047] Figure 7 This is the fluorescence emission spectrum of the blue light-emitting lead-based halide of Example 3 of the present invention;

[0048] Figure 8 This is a fluorescence quantum efficiency diagram of the blue light-emitting lead-based halide of Example 1 of the present invention;

[0049] Figure 9 This is a fluorescence quantum efficiency diagram of a blue light-emitting lead-based halide from Embodiment 2 of the present invention.

[0050] Figure 10 This is a fluorescence quantum efficiency diagram of the blue light-emitting lead-based halide of Example 3 of the present invention;

[0051] Figure 11 This is a fluorescence lifetime decay diagram of a blue light-emitting lead-based halide from Example 1 of the present invention.

[0052] Figure 12 This is a fluorescence lifetime decay diagram of a blue light-emitting lead-based halide from Example 2 of the present invention.

[0053] Figure 13 This is a fluorescence lifetime decay diagram of the blue light-emitting lead-based halide of Example 3 of the present invention;

[0054] Figure 14 The CIE coordinates of the blue light-emitting lead-based halides in Examples 1-3 of this invention;

[0055] Figure 15 Light yield test of the blue light emitting lead-based halide of Embodiment 1 of the present invention under X-ray irradiation;

[0056] Figure 16 Light yield test of lead-based halides that emit blue light under X-ray irradiation in Example 2 of the present invention;

[0057] Figure 17 Light yield test of lead-based halides that emit blue light under X-ray irradiation in Example 3 of the present invention;

[0058] Figure 18 Testing the light yield of commercial LYSO under X-ray irradiation;

[0059] Figure 19 The fluorescence emission spectrum of the material in Comparative Example 1 of this invention is shown.

[0060] Figure 20 The fluorescence emission spectrum of the material in Comparative Example 2 of this invention is shown.

[0061] Figure 21 The fluorescence emission spectra of the materials in Comparative Examples 3 and 4 of this invention are shown.

[0062] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] With societal development, the demand for monochromatic light-emitting materials in red, green, and blue primary colors is increasing. However, currently, the efficiency and stability of blue light, especially saturated deep blue light, lag far behind those of red and green light. A narrow half-width at half-maximum (HWHM) ensures high color purity in fluorescent materials. Higher color purity results in a wider color gamut, which is beneficial for reducing LED power consumption. Existing high-efficiency narrowband blue light-emitting materials are mainly achieved through all-inorganic halide materials, which have poor structural stability and require high excitation energy.

[0065] Organic-inorganic hybrid metal halide materials are a class of materials composed of organic cations and inorganic metal halide anions. Due to their unique structure and excellent luminescent properties, organic-inorganic hybrid metal halide materials have great application potential in the field of lighting displays. Currently reported organic-inorganic hybrid metal halide materials include, for example, (C9NH4+). 20 )7(PbCl4)Pb3Cl 11 The luminous efficiency of CuX2(L5)(tpp)2(5) can reach 83%, and the full width at half maximum (FWHM) of the emission peak is 84 nm. The luminous efficiency of CuX2(L5)(tpp)2(5) can reach 98%, and the FWHM is 82 nm. It can achieve blue light emission, but the FWHM of most materials is greater than 50 nm. That is to say, most organic-inorganic hybrid metal halide materials with blue light emission are broadband emission. In view of this, the present invention provides a lead-based halide that can emit blue light, aiming to provide a lead-based halide material that can emit blue light with high luminous efficiency and narrow band blue light emission.

[0066] In this invention, the general chemical formula of the lead-based halide that emits blue light is A2Pb(X). b ) n (X c ) 4-n ,in:

[0067] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0068] X b Including Cl - or Br - ;

[0069] X c Including Cl - ,Br - and I - Any one of them, and with X b different;

[0070] The value of n is an integer between 1 and 4.

[0071] In any embodiment of the present invention, A is (C16 H 28 N) + Selecting quaternary ammonium salt cations containing benzyl and tripropyl groups is beneficial for forming blue light emitting materials. Moreover, quaternary ammonium salt cations containing benzyl and tripropyl groups are both rigid and flexible, and their molecular volume is sufficient to separate the inorganic metal luminescent centers. They can form stable hydrogen bonds to reduce energy loss caused by non-radiative vibrations, thereby improving luminescence efficiency and reducing the half-maximum width of the emission peak.

[0072] In any embodiment of the present invention, the halide anion includes Cl. - , Br - I - At least one of the halide anions is used to react with the metal ion Pb 2+ They combine to form inorganic metal luminescent centers.

[0073] Lead-based halides with high luminescence efficiency and narrow half-peak width (WHM) emission, capable of emitting blue light, are formed by combining benzyl and tripropyl quaternary ammonium salt cations with halide anions. The benzyl and tripropyl quaternary ammonium salt cations, acting as organic cations, protect and separate the inorganic metal luminescent centers, while the halide anions react with the metal ion Pb. 2+ The inorganic metal luminescent centers are formed by the combination of organic cations and organic cations. The organic cations surround and isolate the inorganic metal luminescent centers. That is, the isolated inorganic metal luminescent centers are separated by a certain distance and periodically distributed in the main framework formed by organic cations, forming a "host-guest" structure. Furthermore, the formation of stable hydrogen bonds can reduce the energy loss caused by non-radiative vibrations, thereby improving luminescence efficiency and reducing the half-maximum width of the emission peak.

[0074] This invention also proposes a method for preparing lead-based halides capable of emitting blue light, the method comprising the following steps:

[0075] An ammonium halide compound containing benzyl and tripropyl groups, a lead halide, and an organic solvent are mixed to obtain a mixture.

[0076] The diffusing agent is diffused into the mixture, precipitating a blue light-emitting lead-based halide. The general chemical formula of the blue light-emitting lead-based halide is A₂Pb(X₂)₃. b ) n (X c ) 4-n ,in:

[0077] A includes quaternary ammonium salt cations containing benzyl and tripropyl groups;

[0078] X b Including Cl - or Br - ;

[0079] X cIncluding Cl - ,Br - and I - Any one of them, and with X b different;

[0080] The value of n is an integer between 1 and 4.

[0081] In any embodiment of the present invention, the molar ratio of the ammonium halide compound containing benzyl and tripropyl to the lead halide is (1.5 to 2.5):1, and within this range, it can be 1.5:1, 1.8:1, 2:1, 2.2:1, or 2.5:1. Preferably, the molar ratio is 2:1. When the molar ratio of the ammonium halide compound containing benzyl and tripropyl to the lead halide is 2:1, it is beneficial for the obtained lead-based halide to achieve high luminous efficiency and a narrow emission peak half-width.

[0082] In any embodiment of the present invention, the ammonium halide compound containing benzyl and tripropyl groups includes at least one of benzyltripropylammonium chloride, benzyltripropylammonium bromide, and benzyltripropylammonium iodide.

[0083] In any embodiment of the present invention, the ammonium halide compound containing benzyl and tripropyl groups includes at least one of benzyltripropylammonium chloride, benzyltripropylammonium bromide, and benzyltripropylammonium iodide. Specifically, it can be any one of these compounds, or it can contain two or more of them simultaneously, all of which fall within the scope of protection of the present invention. The ammonium halide compound containing benzyl and tripropyl groups provides organic cations and halide anions, determining the spacing between the inorganic metal luminescent centers, thereby affecting their chemical properties and stability. Through the ammonium halide compound containing benzyl and tripropyl groups, the inorganic metal luminescent centers are surrounded and separated by the large band gap of the organic cations, resulting in a stable overall structure. Furthermore, a suitable spacing is formed between the inorganic luminescent centers, forming robust hydrogen bonds that reduce energy loss from non-radiative vibrations, thereby improving luminescence efficiency and reducing the half-width at half-maximum (WHM) of the emission peak, resulting in efficient narrow-band emission.

[0084] In any embodiment of the present invention, the lead halide includes at least one of PbCl2, PbBr2, and PbI2.

[0085] The lead halide includes at least one of PbCl2, PbBr2, and PbI2, meaning it can be any one of PbCl2, PbBr2, and PbI2, or it can contain two or more of PbCl2, PbBr2, and PbI2 simultaneously, all of which fall within the scope of protection of this invention. The lead halide also provides a halide anion, which reacts with the metal ion Pb... 2+The halogen anions combine to form inorganic metal luminescent centers. These halide anions originate from ammonium halide compounds containing benzyl and tripropyl groups and lead halides. The emission spectra of zero-dimensional organic-inorganic hybrid lead-based halides prepared from different lead halides exhibit a blue shift with changes in the halogen (I-Br-Cl). Adjusting the halogen content can also enhance the fluorescence quantum yield; the higher the chlorine and bromine content in the prepared zero-dimensional organic-inorganic hybrid lead-based halides, the higher the luminescence efficiency. In the technical solution of this invention, PbCl2 and PbBr2 are preferred lead halides, as they facilitate the formation of efficient narrow-band emission.

[0086] In any embodiment of the present invention, the organic solvent includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEF), and dimethyl sulfoxide (DMSO).

[0087] The organic solvent includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEF), and dimethyl sulfoxide (DMSO). That is, the organic solvent may contain any one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEF), and dimethyl sulfoxide (DMSO), or a mixture of two or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DEF), and dimethyl sulfoxide (DMSO) in any proportion; all of these are within the scope of protection of this invention. The organic solvent allows ammonium halide compounds containing benzyl and tripropyl groups and lead-based halides to dissolve and self-assemble, forming zero-dimensional organic-inorganic hybrid materials. Preferably, N,N-dimethylformamide (DMF) is used as the solvent, which is beneficial for forming lead-based halide materials that emit blue light.

[0088] In any embodiment of the present invention, the dispersant includes at least one of diethyl ether, acetonitrile, acetone, and chloroform.

[0089] The diffusing agent is a solvent with low solubility for dissolving ammonium halide compounds containing benzyl and tripropyl groups, as well as lead halides. The low solubility of the diffusing agent allows for the slow precipitation and growth of zero-dimensional organic-inorganic hybrid single crystals as it slowly evaporates into the solution. In the technical solution of this invention, diethyl ether is preferably used as the diffusing agent, resulting in the best precipitation effect for blue light-emitting lead-based halide crystals.

[0090] The preparation method provided by this invention is simple to synthesize and the raw materials are readily available. At the same time, the lead-based halide that can emit blue light obtained by the preparation method of this invention has high luminous efficiency and a half-width at half maximum (WHM) of less than 50 nm, thereby meeting the current demand for increasingly large-scale high-efficiency narrowband blue light emitting materials.

[0091] This invention also proposes a white LED, including a blue LED chip. The blue LED chip comprises the aforementioned blue-light-emitting lead-based halide, or a blue-light-emitting lead-based halide prepared by the aforementioned method. The white LED incorporates all the technical solutions of blue-light-emitting lead-based halides, and therefore possesses all the beneficial effects of blue-light-emitting lead-based halides, which will not be elaborated upon here.

[0092] This invention also proposes an LED display backlight module, comprising an LED backlight material, wherein the LED backlight material comprises the aforementioned blue light-emitting lead-based halide, or a blue light-emitting lead-based halide prepared by the aforementioned method for preparing blue light-emitting lead-based halide. The LED display backlight module incorporates all the technical solutions of blue light-emitting lead-based halides, and therefore possesses all the beneficial effects of blue light-emitting lead-based halides, which will not be elaborated upon here.

[0093] Furthermore, this invention also proposes an X-ray detector comprising a scintillator material, wherein the scintillator material comprises the aforementioned blue-light-emitting lead-based halide, or a blue-light-emitting lead-based halide prepared by the aforementioned method for preparing blue-light-emitting lead-based halides. The X-ray detector incorporates all the technical solutions of blue-light-emitting lead-based halides, and therefore possesses all the beneficial effects of blue-light-emitting lead-based halides, which will not be elaborated upon here.

[0094] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are merely illustrative of the present invention and are not intended to limit the present invention. In the following specific embodiments and comparative examples, N,N-dimethylformamide (DMF) is selected as the organic solvent, and diethyl ether is selected as the dispersant.

[0095] Example 1

[0096] A lead-based halide that emits blue light, with the chemical formula (TPBA)2PbCl4, is prepared as follows:

[0097] (1) Mix 2 mol of benzyltripropylammonium chloride (TPBA)Cl, 1 mol of PbCl2 and 50 mL of N,N-dimethylformamide (DMF) to obtain a mixture;

[0098] (2) Diffusion of 50 mL of diethyl ether into the mixture precipitates lead-based halide crystals that emit blue light.

[0099] Example 2

[0100] A lead-based halide that emits blue light, with the chemical formula (TPBA)2PbCl2Br2, is prepared as follows:

[0101] (1) Mix 2 mol of benzyltripropylammonium chloride (TPBA)Cl, 0.5 mol of PbCl2 and 0.5 mol of PbBr2 and 50 mL of N,N-dimethylformamide (DMF) to obtain a mixture;

[0102] (2) Diffusion of 50 mL of diethyl ether into the mixture precipitates lead-based halide crystals that emit blue light.

[0103] Example 3

[0104] A lead-based halide that emits blue light, with the chemical formula (TPBA)2PbBr4, is prepared as follows:

[0105] (1) Mix 2 mol of benzyltripropylammonium chloride (TPBA)Cl, 1 mol of PbBr2 and 50 mL of N,N-dimethylformamide (DMF) to obtain a mixture;

[0106] (2) Diffusion of 50 mL of diethyl ether into the mixture precipitates lead-based halide crystals that emit blue light.

[0107] Example 4

[0108] A lead-based halide that emits blue light, with the chemical formula (TPBA)2PbCl2I2, is prepared as follows:

[0109] (1) Mix 2 mol of benzyltripropylammonium iodide (TPBA)I, 0.5 mol of PbCl2 and 0.5 mol of PbI2 and 50 mL of N,N-dimethylformamide (DMF) to obtain a mixture;

[0110] (2) Diffusion of 50 mL of diethyl ether into the mixture precipitates lead-based halide crystals that emit blue light.

[0111] Example 5

[0112] A lead-based halide that emits blue light, with the chemical formula (TPBA)2PbCl4, is prepared as follows:

[0113] (1) Mix 1.5 mol of benzyltripropylammonium chloride (TPBA)Cl, 1 mol of PbCl2 and 50 mL of N,N-dimethylformamide (DMF) to obtain a mixture;

[0114] (2) Diffusion of 50 mL of diethyl ether into the mixture precipitates lead-based halide crystals that emit blue light.

[0115] Example 6

[0116] A lead-based halide that emits blue light, with the chemical formula (TPBA)2PbCl4, is prepared as follows:

[0117] (1) Mix 2.5 mol of benzyltripropylammonium chloride (TPBA)Cl, 1 mol of PbCl2 and 50 mL of N,N-dimethylformamide (DMF) to obtain a mixture;

[0118] (2) Diffusion of 50 mL of diethyl ether into the mixture precipitates lead-based halide crystals that emit blue light.

[0119] Comparative Example 1

[0120] Comparative Example 1 is the same as Example 1 except that it does not contain PbCl2.

[0121] The preparation method of Comparative Example 1 failed to precipitate crystals. Since Comparative Example 1 does not contain PbCl2, it cannot form optically active inorganic metal luminescent centers and cannot form zero-dimensional organic-inorganic hybrid halides. Therefore, Comparative Example 1 cannot precipitate lead-based halide crystals that emit blue light.

[0122] Comparative Example 2

[0123] Comparative Example 2 is the same as Example 1 except that it does not contain benzyltripropylammonium chloride (TPBA)Cl.

[0124] The preparation method of Comparative Example 2 failed to precipitate crystals. Since Comparative Example 2 does not contain benzyltripropylammonium chloride (TPBA)Cl, it cannot provide organic cations and cannot form organic-inorganic hybrid halides. Therefore, Comparative Example 2 could not precipitate lead-based halide crystals that emit blue light.

[0125] Comparative Example 3

[0126] Compared with Example 3, Comparative Example 3 uses tetrapropylammonium bromide (TAPBA) instead of benzyltripropylammonium chloride (TPBA)Cl, otherwise it is the same as Example 3.

[0127] The chemical formula of the crystal material obtained in Comparative Example 3 is (TAPBA)2PbBr4. Since the organic cation in Comparative Example 3 is tetrapropylammonium bromide, which lacks the rigid benzyltripropylammonium bromide, the rigidity of the metal halide crystal structure is reduced, which is not conducive to reducing nonradiative energy loss caused by molecular thermal vibration. The lack of benzyl ring also leads to a shorter distance between the inorganic metal luminescent centers, which is not conducive to reducing self-absorption. Therefore, the lead-based halide crystal obtained in Comparative Example 3 exhibits weak blue light emission.

[0128] Comparative Example 4

[0129] Compared with Example 3, Comparative Example 4 uses benzyltriethylammonium bromide (TEBA) instead of benzyltripropylammonium chloride (TPBA)Cl, otherwise it is the same as Example 3.

[0130] The chemical formula of the crystal material obtained in Comparative Example 4 is (TEBA)2PbBr4. Since the organic cation in Comparative Example 4 is benzyltriethylammonium bromide, the alkyl chain of benzyltriethylammonium bromide is shorter than that of benzyltripropylammonium chloride. Therefore, the distance between the inorganic metal luminescent centers is shorter, and the effect of the organic cation encapsulating the inorganic metal luminescent centers is also worse. The organic cation does not play a role in protecting and separating the inorganic metal luminescent centers, which is not conducive to fluorescence emission. Therefore, a lead-based halide that can emit blue light cannot be obtained. Thus, the lead-based halide crystal obtained in Comparative Example 4 exhibits no fluorescence emission.

[0131] Comparative Example 5

[0132] Compared with Example 3, Comparative Example 5 uses benzyltributylammonium bromide instead of benzyltripropylammonium chloride (TPBA)Cl, otherwise it is the same as Example 3.

[0133] The preparation method of Comparative Example 5 failed to precipitate crystals. Because the organic cation in Comparative Example 5 was benzyltributylammonium bromide, the alkyl chain of benzyltriethylammonium bromide was longer than that of benzyltripropylammonium chloride, increasing the flexibility of the organic cation. This prevented the inorganic metal luminescent centers from being separated and periodically distributed within the main framework formed by the organic cation, thus preventing the formation of a stable structure and the acquisition of blue-light-emitting lead-based halide. Therefore, Comparative Example 5 could not precipitate blue-light-emitting lead-based halide crystals.

[0134] Performance testing

[0135] The blue-light-emitting lead-based halide crystals prepared in Examples 1-3 were subjected to crystal structure, optical properties, and CIE coordinate measurements. The results are as follows:

[0136] The blue-light-emitting lead-based halides prepared in Examples 1-3 were subjected to single-crystal diffraction to obtain their diffraction crystal structure diagrams, as shown below. Figure 1 .Depend on Figure 1 It can be seen that the quaternary ammonium salt type cation (C) contains benzyl and tripropyl groups. 16 H 28 N) + Separate the inorganic metal centers, such that the inorganic metal centers [Pb(X b ) n (X c ) 4-n ] 2- (X b =Cl - ,Br - ;Xc =Cl - ,Br - I - (The values ​​of n are integers between 1 and 4) are separated from each other to form zero-dimensional lead-based halide crystals.

[0137] The blue-light-emitting lead-based halide crystals obtained in Examples 1-3 were ground into solid powder materials, and XRD patterns were obtained by X-ray diffraction. The blue-light-emitting lead-based halide crystals obtained in Examples 1-3 are (TPBA)₂PbCl₄, (TPBA)₂PbCl₂Br₂, and (TPBA)₂PbBr₄, respectively. See also Figures 2-4 The XRD patterns obtained from the crystals in Examples 1-3 are consistent with the XRD diffraction patterns simulated from single crystals, indicating that they have high phase purity.

[0138] The blue-light-emitting lead-based halide crystals prepared in Examples 1-3 were subjected to excitation-emission spectroscopy analysis to obtain fluorescence excitation-emission spectra. The half-maximum width (WHM) of the emission peak was calculated based on the peak width at half the height of the fluorescence emission peak. (See also...) Figures 5-7 As shown in Table 1, the emission wavelengths of (TPBA)₂PbCl₄, (TPBA)₂PbCl₂Br₂, and (TPBA)₂PbBr₄ are 425 nm, 450 nm, and 465 nm, respectively, and all exhibit narrow-band blue light emission with a peak width at half maximum (FWHM) of 49 nm. The optimal excitation wavelengths are 330 nm, 340 nm, and 365 nm, respectively. By changing the halogen elements, the electronic structure of metal halides, as well as the relative energy levels of free excitons and trapped excitons, can be effectively controlled. Changing the halogen element ratio, from Br to Cl, results in a blue shift in the emission wavelength.

[0139] The fluorescence quantum yield (PLQY) plot was obtained by measuring the fluorescence quantum yield using a fluorescence spectrometer equipped with an integrating sphere. See also... Figures 8-10 According to Table 1, the fluorescence quantum efficiencies of (TPBA)2PbCl4, (TPBA)2PbCl2Br2 and (TPBA)2PbBr4 are 100%, 98% and 96%, respectively.

[0140] The time-correlated single-photon technique of a fluorescence spectrometer was used to collect 10,000 counts, and the average fluorescence lifetime was obtained through exponential fitting. See also... Figures 11-13 As shown in Table 1, the fluorescence lifetimes of (TPBA)2PbCl4, (TPBA)2PbCl2Br2 and (TPBA)2PbBr4 are 317.3 ns, 264.1 ns and 255.2 ns, respectively. The fluorescence lifetimes are relatively long, and the blue-emitting lead-based halides prepared tend to be attributed to triplet self-trapped exciton (STE) luminescence.

[0141] The CIE coordinates were obtained from the emission spectrum. (See [link]) Figure 14 As shown in Table 1, the CIE chromaticity coordinates (CIE) of (TPBA)2PbCl4, (TPBA)2PbCl2Br2, and (TPBA)2PbBr4 are (0.16, 0.02), (0.14, 0.05), and (0.13, 0.08), respectively. This indicates that their blue light falls between deep blue and standard blue light, and are all blue light with application value, with the potential to be applied to wide color gamut LED displays.

[0142] Table 1. Performance tests of lead-based halide crystals prepared in Examples 1-3

[0143]

[0144]

[0145] The lead-based halide crystals that emit blue light, prepared in Examples 1-3, were subjected to X-ray irradiation for light yield testing using an X-ray analyzer. Figures 15-18 As shown in Table 2, the lead-based halide crystals that emit blue light prepared in Examples 1-3 have light yields of 18,000, 14,000, and 19,000 photons MeV under X-ray irradiation, respectively. -1 This demonstrates the potential for application as an X-ray scintillator.

[0146] Table 2. Photovoltaic yield of (TPBA)₂PbCl₄, (TPBA)₂PbCl₂Br₂, and (TPBA)₂PbBr₄ for commercial LYSO.

[0147] Chemical formula <![CDATA[Light yield(photons MeV -1 )]]> Example 1 <![CDATA[(TPBA)2PbCl4]]> 18000 Example 2 <![CDATA[(TPBA)2PbCl2Br2]]> 14000 Example 3 <![CDATA[(TPBA)2PbBr4]]> 19000 LYSO (commercial) 24000

[0148] Fluorescence emission spectra were obtained by analyzing the excitation and emission spectra of the materials obtained in Comparative Examples 1-4. Figure 19 The fluorescence emission spectrum of Comparative Example 1 is shown. Figure 20 The fluorescence emission spectrum of Comparative Example 2 is shown. Figure 21 The fluorescence emission spectra are for comparative examples 3 and 4. (From...) Figures 5-7 , Figure 19 and Figure 20 It can be seen that the fluorescence emission peak shapes of the materials obtained in Comparative Examples 1 and 2 are significantly different from those of the materials in Examples 1-3, and the fluorescence intensity of the materials in Comparative Examples 1 and 2 is much lower than that of the materials in Examples 1-3. Therefore, the preparation methods of Comparative Examples 1 and 2 cannot yield lead-based halide crystals that emit blue light. Figure 7 and Figure 21It can be seen that the fluorescence emission peak position of the material obtained in Comparative Example 3 is different from that in Example 3, and the fluorescence intensity of the material obtained in Comparative Example 3 is much lower than that of the material in Example 3. The material obtained in Comparative Example 4 has no fluorescence emission peak. Therefore, the preparation methods of Comparative Example 3 and Comparative Example 4 cannot obtain lead-based halide crystals that emit blue light.

[0149] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A lead-based halide that emits blue light, characterized in that, The general chemical formula is A2Pb(X) b )n(X c )4-n, where: A is a benzyltripropyl quaternary ammonium salt type cation; X b For Cl - or Br - ; X c For Cl - ,Br - and I - Any one of them, and with X b different; The value of n is an integer between 1 and 4.

2. A method for preparing a lead-based halide capable of emitting blue light as described in claim 1, characterized in that, Includes the following steps: A mixture is prepared by mixing benzyltripropylammonium halide, lead halide, and an organic solvent. The diffuser is diffused into the mixture, precipitating a lead-based halide that emits blue light.

3. The method for preparing lead-based halides capable of emitting blue light as described in claim 2, characterized in that, The molar ratio of the benzyltripropylammonium halide compound to the lead halide is (1.5–2.5):

1.

4. The method for preparing a lead-based halide capable of emitting blue light as described in claim 2, characterized in that, The benzyltripropylammonium halide compound is at least one of benzyltripropylammonium chloride, benzyltripropylammonium bromide, and benzyltripropylammonium iodide.

5. The method for preparing a lead-based halide capable of emitting blue light as described in claim 2, characterized in that, The lead halide is at least one of PbCl2, PbBr2, and PbI2.

6. The method for preparing a lead-based halide capable of emitting blue light as described in claim 2, characterized in that, The organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

7. The method for preparing a lead-based halide capable of emitting blue light as described in claim 2, characterized in that, The dispersant includes at least one of diethyl ether, acetonitrile, acetone, and chloroform.

8. A white LED, characterized in that, The white LED includes a blue LED chip, wherein the blue LED chip uses the lead-based halide that emits blue light as described in claim 1, or the lead-based halide that emits blue light prepared by the method described in any one of claims 2-7.

9. An LED display backlight module, characterized in that, The LED display backlight module comprises an LED backlight material, wherein the LED backlight material comprises the blue light emitting lead-based halide as described in claim 1, or the blue light emitting lead-based halide prepared by the method described in any one of claims 2-7.

10. An X-ray detector, characterized in that, The X-ray detector includes a scintillator material, wherein the scintillator material includes the blue-light-emitting lead-based halide of claim 1, or the blue-light-emitting lead-based halide prepared by the method of any one of claims 2-7.

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