A calcium-based perovskite white light crystal material with tunable light color and its preparation.

Abstract

This invention discloses a calcium-based perovskite white light crystal material with tunable light color and its preparation method. The chemical composition of this material is ACa. 1‑x Cl3:xMn 2+ The material contains x = 1–10%, and A is an alkali metal. The preparation method is as follows: using alkali metal chlorides, CaCl2, and MnCl2 as raw materials, and a 20%–30% HCl aqueous solution as the medium, the reaction is carried out at 25–180℃ for 3–12 hours. After filtration and drying, white crystals are obtained. The product emits bright blue, yellow, and white light of different color temperatures under ultraviolet light. This material may be applied to dual-color white LEDs and can also be used for anti-counterfeiting. The product has uniform particles, does not contain toxic elements, has abundant raw materials, and a simple preparation method, making it suitable for industrial production. The tunable light color of this crystal material gives it broad prospects for application in the lighting and anti-counterfeiting fields.

Description

Technical Field

[0001] This invention relates to luminescent materials, and in particular to a calcium-based perovskite white light crystal material with tunable light color. Specifically, the material emits bright blue light, yellow light, and white light of different color temperatures under ultraviolet light, making it suitable for use in dual-color white LEDs and anti-counterfeiting applications. Background Technology

[0002] In the fields of optoelectronics and solid-state lighting, the pursuit of efficient, environmentally friendly, and cost-effective luminescent materials has driven significant progress. Recently, research on all-inorganic halide perovskite crystals has attracted widespread attention due to their potential in applications such as lighting, displays, and sensing. They possess broad band structures and can achieve multicolor emission by adjusting composition and structure. In particular, the stability and luminous efficiency of all-inorganic perovskite materials have been significantly improved, making them a research hotspot for next-generation luminescent materials. [Angew. Chem. Int. Ed. 2020, 59, 12709-12713.] However, some known all-inorganic perovskite luminescent materials contain toxic elements such as lead (Pb) and cadmium (Cd), raising environmental and health concerns. Therefore, there is an urgent need to develop non-toxic alternatives with ideal luminescent properties.

[0003] Successfully synthesized non-toxic materials, such as halide perovskites Cs3Cu2X5 (X = Cl, Br, I), A2InX5·H2O (A = Rb, Cs; X = Cl, Br):Sb, Cs2NaInCl6:Sb, and CsxSnBr x+2 @CsBr et al. successfully solved the toxicity problem associated with traditional perovskite luminescent materials. [Chem. Mater. 2017, 29, 4129-4145.] However, further exploration of various strategies is needed to improve the performance of luminescent materials. This includes improving photoluminescence quantum yield (PLQY), stability, and color tunability. To achieve practical applications, cost-effective and environmentally friendly methods for large-scale synthesis of luminescent materials must be developed, along with improved PLQY. Optimizing synthesis conditions, exploring new precursor materials, and developing innovative growth techniques are key steps in achieving this goal.

[0004] Achieving precise control over spectral modulation and understanding composition-related luminescence mechanisms are ongoing research efforts. Doping / alloying metal cations in perovskite structures has emerged as a promising approach for modulating the performance of halide-based inorganic phosphors, offering the potential to improve efficiency and stability. In Cs₂ZrCl₆:Te 4+ Add a small amount of Rb + It was found that doping Sb could enhance its photoluminescence (PL) intensity and moisture resistance. Similarly, zero-dimensional (0D) doping of Sb... 3+In the (NH4)4CdCl6 halide, tunable warm white light emission was achieved through A-site Rb alloying, increasing PLQY from 62% to 71%. [Chem. Mater. 2023, 35, 948-953.]

[0005] Despite the immense potential of all-inorganic, non-toxic perovskite luminescent materials in optoelectronics, several challenges remain. First, the fabrication process requires more precise control and optimization to achieve high-efficiency luminescence performance. Second, the cost and production scale of these materials also need further optimization to meet the demands of practical applications. Furthermore, the performance of all-inorganic, non-toxic perovskite luminescent materials in terms of multicolor and white light emission still needs further improvement. Summary of the Invention

[0006] The development of efficient, non-toxic, and cost-effective white light emitters is crucial for advancing lighting technology. Here, we develop a novel all-inorganic perovskite crystal, ACa. 1-x Cl3:xMn 2+ Breakthrough research has revealed that this crystal exhibits tunable white light emission. This ACaCl3 (A = one or two of Li, Na, K, Rb, and Cs) matrix represents an unprecedented and unique advancement, demonstrating non-toxic, affordable, and cost-effective raw materials, a simple synthesis method, and superior suitability for large-scale applications. The ACaCl3 matrix emits broad-spectrum blue light at 464 nm due to self-trapped ion (STE) emission. Through Mn... 2+ Doping, ACaCl3:Mn 2+ The crystal emits a broad-spectrum yellow light at 564 nm, originating from Mn. 2+4 T 1g → 6 A 1g Leap. It is worth noting that, with Mn 2+ As the concentration increased from 0% to 10%, we observed STE blue light emission towards Mn. 2+ Energy transfer induced by yellow light emission. This interesting finding provides a basis for the energy transfer in single ACaCl3:Mn 2+ The engineered, custom-designed variable color temperature white light composition offers new avenues, covering a range from cool to warm tones, making it ideal for advanced white LED applications.

[0007] To achieve the above objectives, the invention employs a hydrothermal method to synthesize ACa. 1-x Cl3:xMn 2+Crystals. Alkali metal chlorides (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and hydrochloric acid (36.5 wt%) were all purchased directly from the market. For the typical product CsCa... 0.99 Cl3:0.01Mn 2+ The synthesis process includes the following steps: 1 mmol of CsCl, 0.99 mmol of CaCl2, and 0.01 mmol of MnCl2 were mixed with HCl in a 15 mL Teflon reaction vessel. The resulting mixture was reacted under hydrothermal conditions. After the reaction was complete, the autoclave was slowly cooled to room temperature. The obtained crystals were separated from the supernatant by centrifugation, followed by three washes with ethanol and drying.

[0008] Further settings are ACaCl3:Mn 2+ In this context, A is one or more of Li, Na, K, Rb, and Cs, and the central ion is Ca. 2+ .

[0009] A further setting is that all metal salt raw materials are chlorides, and the alkali metal chlorides are one or two of LiCl, NaCl, KCl, RbCl, and CsCl.

[0010] A further setting involves using a 20%–30% HCl aqueous solution as the medium.

[0011] Further settings are between 25 and 180°C.

[0012] Further set the reaction time to 3–12 hours.

[0013] Further drying conditions were set: 12 hours at 60°C.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] This study effectively achieved blue light emission from the matrix itself and Mn2+ ions by simply doping ACaCl3 with common Mn2+ ions. 2+4 T 1g → 6 A 1g The complementary combination of yellow light emission produced by the transition significantly simplifies the composition of white light emitters, opening up new possibilities for practical applications. This invention provides a simpler, more cost-effective, and efficient method to achieve white light emission. Attached Figure Description

[0016] 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, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0017] Figure 1 Blue light spectrum of CsCaCl3 synthesized by the technique in Example 1 of this invention.

[0018] Figure 2 XRD pattern of CsCaCl3:2%Mn synthesized using the technology of Example 2 of this invention.

[0019] Figure 3 XPS image of CsCaCl3:2%Mn synthesized using the technology of Example 2 of this invention.

[0020] Figure 4 White light spectrum of CsCaCl3:2%Mn synthesized by the technique in Example 2 of this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Example 1

[0023] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl and 1 mmol of CaCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 160°C for 12 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 12 hours. The product obtained in this example emitted bright blue light under near-ultraviolet irradiation, and its fluorescence spectrum is shown in Figure [Figure number missing]. Figure 1 As shown.

[0024] Example 2

[0025] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.98 mmol of CaCl2, and 0.02 mmol of MnCl2 were mixed with 25% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 160°C for 12 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 12 hours. The product obtained using this example emitted a bright, pure white light under near-ultraviolet irradiation. (See attached...) Figure 2 The XRD pattern shown indicates that the product treated with the technique of this invention is a pure-phase CsCaCl3, and trace Mn doping did not affect the crystalline phase. (See attached image) Figure 3 XPS further confirmed the elemental composition of the product, confirming it to be CsCaCl3:Mn. 2+ As attached Figure 4 As shown, the CsCaCl3:Mn obtained in this embodiment 2+ The fluorescence spectrum shows blue and yellow light, which complement each other to form a warm white light visible to the naked eye. The XRD, XPS, and fluorescence spectra of other embodiments are basically similar to those of this embodiment and will not be described in detail.

[0026] Example 3

[0027] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.997 mmol of CaCl2, and 0.003 mmol of MnCl2 were mixed with 20% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 25°C for 12 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 40°C for 12 hours. The product obtained in this example emitted a bright, cool white light under near-ultraviolet irradiation.

[0028] Example 4

[0029] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.992 mmol of CaCl2, and 0.008 mmol of MnCl2 were mixed with 40% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 60°C for 10 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 50°C for 8 hours. The product obtained in this example emitted a bright, cool white light under near-ultraviolet irradiation.

[0030] Example 5

[0031] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.99 mmol of CaCl2, and 0.01 mmol of MnCl2 were mixed with 20% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 140°C for 11 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 40°C for 8 hours. The product obtained in this example emitted a bright, pure white light under near-ultraviolet irradiation.

[0032] Example 6

[0033] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.98 mmol of CaCl2, and 0.02 mmol of MnCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 80°C for 7 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 3 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0034] Example 7

[0035] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.97 mmol of CaCl2, and 0.03 mmol of MnCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 80°C for 7 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 3 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0036] Example 9

[0037] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.95 mmol of CaCl2, and 0.05 mmol of MnCl2 were mixed with 20% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 180°C for 3 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 50°C for 3 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0038] Example 10

[0039] The raw materials used included CsCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of CsCl, 0.90 mmol of CaCl2, and 0.1 mmol of MnCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 140°C for 9 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 50°C for 5 hours. The product obtained in this example exhibited a yellowish fluorescence under near-ultraviolet irradiation.

[0040] Example 11

[0041] The raw materials used included LiCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol LiCl, 0.97 mmol CaCl2, and 0.03 mmol MnCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 80°C for 7 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 3 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0042] Example 12

[0043] The raw materials used included LiCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol LiCl, 0.95 mmol CaCl2, and 0.05 mmol MnCl2 were mixed with 20% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 180°C for 3 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 50°C for 3 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0044] Example 13

[0045] The raw materials used included LiCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol LiCl, 0.90 mmol CaCl2, and 0.1 mmol MnCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 140°C for 9 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 50°C for 5 hours. The product obtained in this example exhibited a yellowish fluorescence under near-ultraviolet irradiation.

[0046] Example 14

[0047] The raw materials used included NaCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol NaCl, 0.97 mmol CaCl2, and 0.03 mmol MnCl2 were mixed with 20% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 140°C for 11 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 40°C for 8 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0048] Example 15

[0049] The raw materials used included NaCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol NaCl, 0.98 mmol CaCl2, and 0.02 mmol MnCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 80°C for 7 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 3 hours. The product obtained in this example emitted a bright, warm white light under near-ultraviolet irradiation.

[0050] Example 16

[0051] The raw materials used included KCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of KCl, 0.997 mmol of CaCl2, and 0.003 mmol of MnCl2 were mixed with 20% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 25°C for 12 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 40°C for 12 hours. The product obtained in this example emitted a bright, cool white light under near-ultraviolet irradiation.

[0052] Example 17

[0053] The raw materials used included KCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol KCl, 0.992 mmol CaCl2, and 0.008 mmol MnCl2 were mixed with 40% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 60°C for 10 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 50°C for 8 hours. The product obtained in this example emitted a bright, cool white light under near-ultraviolet irradiation.

[0054] Example 18

[0055] The raw materials used included RbCl (99.9%), CaCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol of RbCl and 0.99 mmol of CaCl2 were mixed with 30% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 160°C for 12 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 12 hours. The product obtained in this example emitted a bright blue light under near-ultraviolet irradiation.

[0056] Example 19

[0057] The raw materials used included RbCl (99.9%), CaCl2 (99.9%), MnCl2 (99.9%), and HCl hydrochloric acid (36.5 wt%). The preparation process included the following steps: 1 mmol RbCl, 0.99 mmol CaCl2, and 0.01 mmol MnCl2 were mixed with 25% HCl to form a 5 mL precursor solution, which was then placed in a 15 mL polytetrafluoroethylene-lined reaction vessel. The mixture was subjected to hydrothermal treatment at 160°C for 12 hours. After completion, the reaction vessel was slowly cooled to room temperature. The crystals and supernatant were separated by centrifugation. Subsequently, the crystals were washed three times with ethanol and dried at 60°C for 12 hours. The product obtained in this example emitted a bright, pure white light under near-ultraviolet irradiation.

[0058] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A calcium-based perovskite white light crystal material with tunable light color, characterized in that: The chemical composition of this material is ACa. 1-x Cl3:xMn 2+ Where x ranges from 1 to 10%, and A = one or two of Li, Na, K, Rb, and Cs, the preparation method of the white light crystal material includes the following steps: using one or two of alkali metal chlorides LiCl, NaCl, KCl, RbCl, and CsCl, and CaCl2 and MnCl2 as raw materials, using a 20% to 30% HCl aqueous solution as the medium, reacting at 25 to 180°C for 3 to 12 hours, filtering and drying to obtain white crystals, and the material can emit bright blue light, yellow light and white light of different color temperatures under ultraviolet light, which is suitable for two-primary-color white light LEDs and anti-counterfeiting fields.

2. The method for preparing a calcium-based perovskite white light crystal material with tunable light color as described in claim 1, characterized in that, The method includes the following steps: using one or two of the alkali metal chlorides LiCl, NaCl, KCl, RbCl, CsCl, CaCl2 and MnCl2 as raw materials, using an aqueous solution of HCl with a mass concentration of 20%~30% as the medium, reacting at 25 to 180°C for 3 to 12 hours, filtering and drying to obtain white crystals.

3. The method for preparing the color-tunable calcium-based perovskite white light crystal material according to claim 2, characterized in that, The drying temperature of the calcium-based perovskite white light crystal material is 40 to 60°C, and the drying time is 3 to 6 hours.

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