Preparation method of bismuth-based halide perovskite ultraviolet fluorescent powder, product and application thereof

Abstract

This invention discloses a method for preparing bismuth-based halide perovskite phosphors, along with their products and applications. The phosphor's chemical composition is AlBiCl6•(DMSO)6, where DMSO is dimethyl sulfoxide. The preparation method includes mixing an aluminum source, a bismuth source, DMSO, and water, heating the mixture to react, then cooling to crystallize. After solid-liquid separation, washing, and drying, the phosphor is obtained. The resulting phosphor exhibits narrow-band ultraviolet emission under ultraviolet light excitation, with an emission peak around 370 nm. Dissolving the phosphor in an acid solution yields fluorescent anti-counterfeiting ink. Patterns formed by applying this ink to a substrate surface are invisible in the unactivated state; after selective wetting with DMSO, they exhibit fluorescence emission under ultraviolet light excitation, achieving reversible "on-off" hiding of information and enabling instrument reading and display. The phosphor provided by this invention is low-cost, stable, and simple to prepare, showing promising application prospects in UVA-LED, UV curing, forensic evidence detection, and high-end anti-counterfeiting inks.

Description

Technical Field

[0001] This invention relates to the fields of inorganic semiconductor light-emitting materials technology and anti-counterfeiting technology, specifically to a method for preparing bismuth-based halide perovskite ultraviolet phosphor, its products, and applications. Background Technology

[0002] Hybrid halide perovskite materials hold immense application potential in solar cells, photodetectors, lasers, and light-emitting diodes. Among various hybrid metal halide families, low-dimensional systems readily form self-trapped excitons (STEs) due to exciton confinement effects, exhibiting a high photoluminescence quantum yield (PLQY) advantage. However, these materials often contain lead, posing a significant risk of heavy metal leakage and causing substantial potential environmental harm. Furthermore, lead-based perovskites are highly susceptible to decomposition and failure under light or electric fields and are sensitive to oxygen, heat, water, and light, facing severe material instability issues that greatly limit their commercial development.

[0003] The aforementioned challenges have spurred the search for more lead-free, stable optoelectronic materials with similar outer electron configurations. Thanks to the superior structural design capabilities of hybrid halide perovskites, precise control of optical properties can be achieved by selecting and utilizing organic ligands and metal elements, combined with functional groups. Current research mainly focuses on monometallic compounds such as (C9NH20)2SbCl5, RInBr4 (R = trimethyl(4-stilbenyl)methylammonium), and [BzTPP]2Cu2I4 (BzTPP = Benzyltriphenylphosphonium). Experiments show that these materials exhibit good fluorescence efficiency and broad application potential in areas such as X-ray detection. Theoretically, more stable bimetallic materials can be obtained by designing ideal cationic metal ions at the A-site; however, only a few reports have mentioned this, lacking sufficient exploration. Utilizing the coordination of organic cationic ligands with A-site metal ions, the strong coordination between alkaline earth metals and the oxygen atoms of organic ligands facilitates the bonding of the A-site metal and B-site atoms. Among them, A(DMSO) n [SbCl mPrototype compounds formed by combining alkaline earth metals, Mn, or rare earth elements with Sb have been reported (Liu X, Gao X, Xiong L, et al. SmartMat, 2024, 5(4): e1224; Zhang Y, Zhang Y, Zhao Y, et al. Journal of the American Chemical Society, 2023, 145(22):12360-12369; Xu Y, Ding Y, Ding F, et al. Inorganic Chemistry, 2025, 64,11335-11341). The results show that these materials not only possess excellent fluorescence properties and stability, but also have broad application potential in high-end anti-counterfeiting and X-ray detection.

[0004] Bismuth is a non-toxic late transition metal with a wide range of possible valence states, making it a versatile and complex dopant. Materials related to bismuth can be used to construct light-emitting devices. The outer orbitals responsible for light emission are unshielded and strongly influenced by their surroundings, thus their energy is dependent on the host. Bismuth-based perovskite-derived halides can be highly tunable by matching different halogen atoms or A-site elements. Recently, A(DMSO) combined with rare earth elements has been used... n [BiCl m Compounds have also been reported (Lin J, Wang P, Zhou J, et al. Angewandte Chemie International Edition, 2024, 63(29): e202400554), providing templates for designing bimetallic hybrid halides composed of solvent-coordinated metal cations and inorganic polyhedral units. However, the A-site metals in the relevant reports are limited to rare earth elements, which has the disadvantage of high cost; while research on constructing such bimetallic halides using inexpensive metals and bismuth is still very lacking, and related zero-dimensional material research is limited.

[0005] Furthermore, in the fields of anti-counterfeiting and information encryption, existing fluorescent anti-counterfeiting materials mostly employ the principle of photoluminescence, that is, displaying fluorescent information under ultraviolet light of a specific wavelength. The information in this type of anti-counterfeiting technology remains visible in the excited state, lacking sufficient concealment and failing to meet higher-level information hiding requirements. Currently, there is a lack of an anti-counterfeiting material system that combines low cost, high concealment, and reversible fluorescent switching characteristics. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a bismuth-based halide perovskite phosphor and its preparation method, a method for preparing fluorescent anti-counterfeiting ink, an information anti-counterfeiting concealment method, and its application. This bismuth-based halide perovskite ultraviolet phosphor exhibits ultraviolet luminescence, high quantum efficiency, and high stability. Furthermore, dissolving this bismuth-based halide perovskite ultraviolet phosphor material yields a high-end anti-counterfeiting ink for information encryption. Its fluorescence signal is located in the ultraviolet band and requires instrument reading, possessing instrument-level anti-counterfeiting features that are completely invisible to the naked eye.

[0007] The objective of this invention is achieved through the following technical solution: First, the invention provides a bismuth-based halide perovskite phosphor with the chemical composition AlBiCl6•(DMSO)6, wherein DMSO is dimethyl sulfoxide.

[0008] The phosphor is Al 3+ with Bi 3+ A zero-dimensional bimetallic halide structure is formed through chloride ion bridging, with DMSO acting as a solvent molecule and Al... 3+ Coordination occurs, forming [Al(DMSO)6] 3+ The cation complex with [BiCl6] 3- The material has a zero-dimensional structure with alternating anions. Under ultraviolet light excitation, it exhibits narrow-band ultraviolet light emission with an emission peak around 370 nm.

[0009] Secondly, the present invention provides a method for preparing bismuth-based halide perovskite phosphors, comprising the following steps: mixing an aluminum source, a bismuth source, DMSO and water, heating and reacting, then cooling and crystallizing, followed by solid-liquid separation, washing and drying to obtain the phosphor.

[0010] Preferably, the aluminum source is aluminum chloride, the bismuth source is bismuth chloride, and the molar ratio of the aluminum source to the bismuth source is 3:1.

[0011] Preferably, the heating reaction temperature is 140–160°C and the reaction time is 1–4 hours; the cooling crystallization is carried out at a rate of 5–15°C / h to room temperature.

[0012] Preferably, the washing is performed using ethyl acetate, and the drying is performed under vacuum at 45–60°C for 4–10 hours.

[0013] In the above preparation method, aluminum source, bismuth source, DMSO and water are mixed to form a clear precursor solution; during the heating reaction, Al 3+ It coordinates with DMSO to form [Al(DMSO)6] 3+ Meanwhile, Bi 3+ With Cl - [BiCl6] is formed. 3-The two ions assemble through ionic bonds to form a zero-dimensional bimetallic halide crystal, which precipitates out of the solution as the temperature slowly decreases.

[0014] Furthermore, the present invention provides a method for preparing fluorescent anti-counterfeiting ink, wherein the above-mentioned fluorescent powder is dissolved in an acid solution to obtain fluorescent anti-counterfeiting ink.

[0015] Preferably, the acid solution is a hydrochloric acid solution with a concentration of 0.05-0.5M, and the ratio of the amount of phosphor to the amount of hydrochloric acid solution is (0.1-0.3g):(5-8ml).

[0016] In the aforementioned fluorescent anti-counterfeiting ink, the fluorescent powder dissolves in an acidic solution to form a colorless and transparent solution containing AlBiCl6•(DMSO)6 structural units, which can be applied to the substrate surface as ink through printing or writing.

[0017] Then, the present invention provides an information anti-counterfeiting and hiding method, comprising the following steps: An ink containing phosphor is applied to the substrate surface. The ink is prepared by dissolving phosphor in an acid solution and dried to form a phosphor-loaded pattern. The pattern is selectively wetted with DMSO and then dried to complete the luminescence activation. The activated pattern exhibits ultraviolet fluorescence emission with a peak value of 370 nm under excitation light irradiation. The ultraviolet fluorescence emission needs to be read and displayed by a fluorescence detection instrument. In the unactivated state, the pattern does not emit fluorescence under excitation light irradiation.

[0018] Preferably, the excitation light is ultraviolet light with a wavelength of 280-340nm; the pattern is invisible to the naked eye under natural light and conventional ultraviolet light sources (such as 254nm ultraviolet light and 365nm ultraviolet light).

[0019] In the aforementioned information anti-counterfeiting and concealment method, AlBiCl6•(DMSO)6 does not emit fluorescence in its unactivated state. Information reading requires the simultaneous fulfillment of two conditions: selective wetting with DMSO and excitation with ultraviolet light of a specific wavelength. This method possesses a dual activation mechanism and high concealment. The DMSO-induced fluorescence "off-on" response is reversible; it can be restored to the "off" state after drying and reactivated by further DMSO treatment.

[0020] Finally, this invention provides the application of the above-mentioned fluorescent powder in UVA-LED, UV curing, criminal evidence detection, or anti-counterfeiting inks.

[0021] The beneficial effects of this invention are as follows: (1) This invention provides a novel zero-dimensional bismuth-based halide perovskite phosphor with the chemical composition AlBiCl6•(DMSO)6. Compared with the prior art, this material uses inexpensive metal Al to replace rare earth elements, which significantly reduces the material cost. At the same time, it avoids the toxicity problem of lead-based perovskites and has the characteristics of being environmentally friendly and having good thermal stability (weight loss of less than 5% at 200℃). It has broad application prospects in the industry.

[0022] (2) The preparation method provided by the present invention can obtain the target product through simple heating synthesis and cooling crystallization without the need for additional ligands or complex post-processing. It is simple to operate, has a high yield, and is easy to scale up for industrial production.

[0023] (3) The fluorescent anti-counterfeiting ink and information anti-counterfeiting concealment method provided by the present invention utilize the reversible "off-on" fluorescence response behavior of AlBiCl6•(DMSO)6 under DMSO induction to realize the on-demand dynamic concealment of information and instrument reading and display. Its unique feature is that the information is completely invisible under natural light and conventional ultraviolet lamps (254nm, 365nm). After activation under the dual conditions of 320nm ultraviolet light and DMSO treatment, it can generate 370nm ultraviolet fluorescence. This fluorescence signal cannot be directly observed by the naked eye and can only be read by means of a fluorescence spectrophotometer or ultraviolet sensitive imaging equipment. It has extremely high concealment and has instrument-level anti-counterfeiting capabilities. Moreover, the fluorescent switch is reversible and cyclical, supporting low-cost patterning technologies such as screen printing and handwriting, providing a brand-new technical solution for high-end anti-counterfeiting, information encryption, criminal investigation evidence detection and other fields. Attached Figure Description

[0024] Figure 1 These are digital images of the AlBiCl6•(DMSO)6 sample prepared in Example 1 of this invention under sunlight and irradiation with a 365nm ultraviolet lamp. Figure 1 Image a is a digital image of the AlBiCl6•(DMSO)6 sample under sunlight. Figure 1 b is a digital image of the AlBiCl6•(DMSO)6 sample under 365nm ultraviolet light irradiation.

[0025] Figure 2 The PL and PLE spectra of the AlBiCl6•(DMSO)6 sample prepared in Example 1 of this invention (Inset: Image under 365nm UV light).

[0026] Figure 3 Thermogravimetric analysis (TGA) spectrum of the AlBiCl6•(DMSO)6 sample prepared in Example 1 of this invention.

[0027] Figure 4The XRD patterns of the phosphors AlBiX6•(DMSO)6 (X=Cl, Br) and single crystal SC-AlBiCl6•(DMSO)6 prepared in Examples 1 and 2 of this invention are shown.

[0028] Figure 5 The photoluminescence spectra of AlBiX6•(DMSO)6 (X=Cl, Br) prepared in Examples 1 and 2 of this invention are shown.

[0029] Figure 6 The fluorescence efficiency of the phosphor AlBiCl6•(DMSO)6 prepared in Example 1 of this invention is shown.

[0030] Figure 7 This is a demonstration diagram of the special anti-counterfeiting application of the fluorescent powder prepared in Embodiment 1 of the present invention. The diagram is divided into two layers: the upper layer is a schematic diagram of the preparation and patterning process of the fluorescent anti-counterfeiting ink; the lower layer is a comparison of the actual photos of the samples before and after activation with instrument detection. The lower layer is divided into three rows of images: the upper row is a photo of the actual sample under ultraviolet light, the middle row is a photo of the actual sample under sunlight (there is no obvious difference under naked eye observation), and the lower row is the corresponding instrument detection image / spectrum (the difference in fluorescence signal can be clearly distinguished). Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The described embodiments are merely some embodiments of the present invention, and not all embodiments. 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. Example 1

[0032] This embodiment provides a method for preparing a zero-dimensional bismuth-based halide perovskite phosphor, AlBiCl6•(DMSO)6, comprising the following steps: S1. Dissolve 3 mmol (approximately 0.40 g) of aluminum trichloride (AlCl3) in 1 ml of deionized water in a reaction vessel and stir until completely dissolved. Immediately afterwards, add 1 mmol (approximately 0.315 g) of bismuth chloride (BiCl3) and 5 ml of DMSO to the vessel and stir at 650 rpm until a clear and transparent first precursor solution is formed.

[0033] S2. The reactor was placed in an electric thermostatic oven at 150°C and heated for 3 hours. Then, it was slowly cooled to room temperature at a rate of 10°C / h to obtain a second precursor suspension containing white crystals.

[0034] S3. The second precursor suspension was filtered, the filter cake was washed three times with ethyl acetate, and then dried in a vacuum drying oven at 55°C for 6 hours to obtain a white fluorescent powder (e.g., ...). Figure 1 As shown in a), the phosphor exhibits a bright blue fluorescence under ultraviolet light (as shown in a). Figure 1 (as shown in b).

[0035] like Figure 2 and Figure 6 As shown, the photoluminescence properties of the obtained product were tested using a fluorescence spectrophotometer under 330 nm ultraviolet light excitation. The results showed that the emission peak of the phosphor was located at approximately 370 nm (e.g., Figure 2 As shown), it belongs to the ultraviolet band; its fluorescence quantum efficiency is 6.89% (as shown). Figure 6 As shown in the figure, this demonstrates that the material possesses excellent luminescent properties.

[0036] like Figure 3 As shown, thermogravimetric analysis (TGA) under a nitrogen atmosphere shows that the material loses less than 5% of its weight at 200℃, indicating that the material has good thermal stability and can meet the temperature stability requirements in subsequent processing and application.

[0037] The obtained product was characterized by X-ray powder diffraction, and the results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the diffraction peaks of the obtained product are in good agreement with the XRD pattern of the single crystal structure simulation, and no other impurity peaks were observed, indicating that pure phase AlBiCl6•(DMSO)6 phosphor was successfully prepared. Example 2

[0038] This embodiment provides a method for preparing the phosphor AlBiBr6•(DMSO)6, which uses Br to partially replace Cl, and includes the following steps: S1. Dissolve 3 mmol of aluminum tribromide (AlBr3) in 1 ml of deionized water in a reaction vessel and stir until completely dissolved. Then add 1 mmol of bismuth tribromide (BiBr3) and 5 ml of DMSO to the vessel and stir at 650 rpm until a clear and transparent first precursor solution is formed.

[0039] S2. The reaction vessel was placed in an electrically heated constant-temperature oven at 150℃ and heated for 3 hours. Then, it was slowly cooled to room temperature at a rate of 10℃ / h to obtain a second precursor suspension containing crystals. The second precursor suspension was filtered, and the filter cake was washed three times with ethyl acetate. Then, it was dried in a vacuum drying oven at 55℃ for 6 hours to obtain phosphor powder.

[0040] The obtained product was characterized by X-ray powder diffraction, and the results were similar. Figure 4 As shown. By Figure 4 It can be seen that the diffraction peaks of AlBiBr6•(DMSO)6 are in good agreement with the XRD patterns of AlBiCl6•(DMSO)6 and the single-crystal structure simulation, indicating that the material maintains the same crystal structure after Br replaces Cl, and verifying the feasibility of the halogen composition control strategy.

[0041] Photoluminescence spectrum ( Figure 5 The results show that the emission peak of AlBiCl6•(DMSO)6 prepared in Example 1 is located at around 370 nm, while the emission peak of AlBiBr6•(DMSO)6 prepared in this example shows a significant blue shift, indicating that the emission peak position can be effectively adjusted in the ultraviolet band by replacing Cl with Br. This proves that the halogen component regulation strategy provided by this invention can achieve systematic regulation of the luminescence properties of materials, providing a feasible technical path to meet the differentiated emission wavelength requirements of different application scenarios. Example 3

[0042] This embodiment provides a method for preparing fluorescent anti-counterfeiting ink and a method for concealing information to prevent counterfeiting.

[0043] 0.2 g of AlBiCl6•(DMSO)6 powder synthesized in Example 1 was placed in a sealed reaction flask, and 6.5 ml of 0.2 M hydrochloric acid solution (HCl) was added. The mixture was stirred at room temperature for 10 min to form a colorless and transparent precursor ink.

[0044] The filter paper substrate was immersed in the pre-prepared ink. After it was fully absorbed, it was removed and placed in a vacuum drying oven at 70°C for 10 minutes to dry.

[0045] After the solvent has completely evaporated, AlBiCl6•(DMSO)6 is uniformly loaded onto the surface of the filter paper fibers, forming a pattern invisible to the naked eye (e.g. Figure 1 As shown in a, observe under sunlight; as Figure 1 As shown in b, it is not visible even under 365nm ultraviolet light irradiation.

[0046] During information display, DMSO was used to selectively wet the patterned area on the filter paper surface, followed by drying in a 70℃ oven for 10 minutes to complete the luminescence activation. The activated pattern produced ultraviolet fluorescence emission with a peak at 370nm under 320nm ultraviolet light excitation (its photoluminescence spectrum is shown below). Figure 2 and Figure 5 (As shown). Because the emission wavelength is in the ultraviolet band, the fluorescence signal cannot be directly observed with the naked eye and needs to be read and identified using a fluorescence spectrophotometer or ultraviolet-sensitive imaging equipment. Figure 7The image showcases demonstration photos and instrument testing comparisons of the anti-counterfeiting process. The upper layer illustrates the preparation and patterning process of the fluorescent anti-counterfeiting ink; the lower layer is divided into three rows. The top and middle rows show no visible differences between the samples before and after activation under ultraviolet light and sunlight, respectively. However, the corresponding instrument testing images / spectral graphs in the lower row clearly distinguish the differences in fluorescence signals. This precisely confirms its unique advantage as a highly concealed anti-counterfeiting material with instrument-readable display—the fluorescence signal can only be confirmed through instrument analysis, further enhancing the anti-counterfeiting security level. Under natural sunlight or conventional ultraviolet light sources (254nm and 365nm), no luminescence signal is visible to the naked eye (photos under sunlight and 365nm are shown below). Figure 1 a, Figure 1 (as shown in b), possessing excellent concealment.

[0047] The displayed sample was then dried again in a 70°C oven for 10 minutes, at which point the fluorescence signal disappeared, returning the sample to its hidden state. After selective wetting with DMSO again, the fluorescence signal was reactivated, achieving a reversible "off-on" fluorescence response. This process can be repeated multiple times, demonstrating good reversibility and stability.

[0048] The above results indicate that the information anti-counterfeiting and concealment method provided by this invention has the following significant characteristics: (1) Dual activation mechanism: Information reading requires the simultaneous fulfillment of two conditions: 320nm specific wavelength ultraviolet light excitation and DMSO chemical treatment. Neither can be omitted. (2) High concealment: It is completely invisible under natural light and conventional ultraviolet light (254nm, 365nm), effectively avoiding unintentional leakage of information. (3) Reversible fluorescence switch: Through alternating operation of DMSO treatment and drying, multiple "off-on" cycles of fluorescence signal can be achieved.

[0049] This invention provides a method for preparing bismuth-based halide perovskite phosphors, along with their products and applications. It utilizes inexpensive aluminum as a substitute for rare earth elements, resulting in low cost. The preparation method is simple and efficient, requiring no complex equipment or process control, making it suitable for large-scale industrial production. These characteristics enable the method to support high-fidelity information encoding and on-demand dynamic hiding through low-cost, scalable patterning technologies such as screen printing and handwriting. The prepared phosphors and their fluorescent anti-counterfeiting inks have broad application prospects in UVA-LED beads, UV curing, forensic evidence detection, and high-end anti-counterfeiting inks.

[0050] Other aspects of this invention that are not detailed herein are all conventional techniques known to those skilled in the art.

[0051] It should be noted that the terms “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments. Any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of this invention shall fall within the scope of protection of this invention.

Claims

1. A bismuth-based halide perovskite phosphor, characterized in that: The phosphor has the chemical composition AlBiCl6•(DMSO)6, where DMSO is dimethyl sulfoxide.

2. A method for preparing a bismuth-based halide perovskite phosphor, characterized in that, Includes the following steps: An aluminum source, a bismuth source, DMSO and water are mixed, heated to react, and then cooled to crystallize. After solid-liquid separation, washing and drying, the phosphor is obtained.

3. The preparation method according to claim 2, characterized in that: The aluminum source is aluminum chloride, the bismuth source is bismuth chloride, and the molar ratio of the aluminum source to the bismuth source is 3:

1.

4. The preparation method according to claim 2, characterized in that: The heating reaction is carried out at a temperature of 140–160°C for 1–4 hours; the cooling crystallization is carried out by cooling to room temperature at a rate of 5–15°C / h.

5. The preparation method according to claim 2, characterized in that: The washing process is performed using ethyl acetate, and the drying process is performed under vacuum at 45–60°C for 4–10 hours.

6. A method for preparing a fluorescent anti-counterfeiting ink, characterized in that: The fluorescent powder described in claim 1 is dissolved in an acid solution to obtain fluorescent anti-counterfeiting ink.

7. The preparation method according to claim 6, characterized in that: The acid solution is a hydrochloric acid solution with a concentration of 0.05-0.5M, and the ratio of the amount of phosphor to the amount of hydrochloric acid solution is (0.1-0.3g):(5-8ml).

8. A method for preventing information counterfeiting and concealment, characterized in that, Includes the following steps: An ink containing the phosphor of claim 1 is applied to the surface of a substrate. The ink is prepared by dissolving the phosphor of claim 1 in an acid solution and then drying it to form a pattern loaded with the phosphor of claim 1. The pattern is selectively wetted with DMSO, and the luminescence activation is completed after drying. Once activated, the pattern exhibits ultraviolet fluorescence emission with a peak value of 370 nm under excitation light irradiation. This ultraviolet fluorescence emission needs to be read and displayed using a fluorescence detection instrument. In the unactivated state, the pattern does not emit fluorescence under excitation light irradiation.

9. The information anti-counterfeiting and concealment method according to claim 8, characterized in that: The excitation light is ultraviolet light with a wavelength of 280-340 nm; the pattern is invisible to the naked eye under natural light and ultraviolet light with a wavelength of 254 nm and / or 365 nm.

10. The application of the fluorescent powder according to claim 1 in UVA-LED, UV curing, criminal evidence detection or anti-counterfeiting ink.

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