Lead ion doped chloride perovskite photochromic material, preparation method and application thereof, lead ion doped chloride perovskite photochromic film and preparation method thereof

Abstract

The invention provides a lead ion doped chloride perovskite photochromic material, a preparation method and application thereof, a lead ion doped chloride perovskite photochromic film and a preparation method thereof, and belongs to the technical field of photochromic materials. According to the invention, CsCdCl3 is used as a substrate, lead ions are introduced into the substrate, original symmetry is destroyed, and the inorganic halide perovskite material with a chemical formula of CsCd1-aPbaCl3 (wherein a is 0.003-0.1) is obtained, and the material can generate a fast photoresponse speed within a time unit of seconds under the excitation of ultraviolet rays or X-rays so as to generate a color change phenomenon and generate color change. And an optical absorption band of 300-800nm appears in a diffuse reflection spectrum, can reversibly recover after being heated, and is expected to be used in the fields of anti-counterfeit labels, optical storage, visual display or multilayer information encryption.

Description

Technical Field

[0001] The present invention relates to the technical field of photochromic materials, and in particular to a lead ion-doped chloride perovskite photochromic material, a preparation method and application thereof, and a lead ion-doped chloride perovskite photochromic film and a preparation method thereof. Background Art

[0002] Photochromic materials are materials that can gradually change into two distinct states in terms of color, polarity, chemical composition, and fluorescence emission. They can be used in anti-counterfeiting labels, optical storage devices, electronic components, photochemical etching, functional textiles, and photosensitive indoor and outdoor wall decoration. Organic photochromic materials, as a typical example, offer excellent color-changing properties and photostability, but they suffer from poor fatigue resistance, a short lifespan at room temperature, and poor information retention. Compared to organic photochromics, inorganic photochromics offer better high-temperature and fatigue resistance. Their color-changing mechanism is that under illumination with specific wavelengths, electrons in anisotropic structures undergo charge transfer and transitions, resulting in a macroscopic color shift. When the prepared material is exposed to light of a different wavelength or subjected to gradual heat stimulation, it returns to its original state. During this process, acid ions, which can act as key components or harmful impurities, capture electrons released by the light, forming the prerequisite for electron transfer. The most common inorganic photochromic materials are generally classified as transition metal oxides, polyoxometalates, metal halides, and rare earth complexes. However, the poor color contrast of inorganic matrices often results in a low signal-to-noise ratio and a response delay, which affects their performance as optoelectronic devices. At the same time, considering the difficulty in processing color-changing ceramics, it is crucial to develop color-changing materials with a high signal-to-noise ratio and strong plasticity with a fast light response. Summary of the Invention

[0003] The purpose of the present invention is to provide a lead ion-doped chloride perovskite photochromic material, a preparation method and application thereof, a lead ion-doped chloride perovskite photochromic film and a preparation method thereof, so as to overcome the problems of poor color contrast, low signal-to-noise ratio and slow response speed of current inorganic photochromic materials.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a lead ion doped chloride perovskite photochromic material, the chemical composition of which is CsCd 1- a Pb a Cl3, wherein a is 0.003 to 0.1.

[0006] The present invention provides a method for preparing a lead ion-doped chloride perovskite photochromic material, comprising the following steps:

[0007] As described CsCd 1-a Pb a CsCl, CdCl2 and PbCl2 are mixed with an acid solution in a stoichiometric ratio of Cl3 to obtain a precursor mixture;

[0008] The precursor mixture is subjected to a hydrothermal reaction to obtain a lead ion-doped chloride perovskite photochromic material.

[0009] Preferably, the acid solution comprises a hydrochloric acid aqueous solution with a mass concentration of 20 to 36%.

[0010] Preferably, the temperature of the hydrothermal reaction is 150-200° C., and the time is 10-24 hours.

[0011] Preferably, after the hydrothermal reaction, the obtained product is washed and dried in sequence; the cleaning agent used for the washing includes isopropanol, methanol or propanol, and the drying temperature is 60 to 80° C. and the drying time is 12 to 24 hours.

[0012] The present invention provides the use of the lead ion-doped chloride perovskite photochromic material or the lead ion-doped chloride perovskite photochromic material prepared by the above preparation method in anti-counterfeiting labels, optical storage, visual display or multi-layer information encryption.

[0013] The present invention provides a method for preparing a lead ion-doped chloride perovskite photochromic film, comprising the following steps:

[0014] The photochromic material, silicone and curing agent are mixed and poured into a mold, and then vented and heated to cure in sequence to obtain a photochromic material film;

[0015] The photochromic material is the lead ion-doped chloride perovskite photochromic material or the lead ion-doped chloride perovskite photochromic material prepared by the above preparation method.

[0016] Preferably, the siloxane comprises ethylene-terminated long-chain dimethylsiloxane; and the mass ratio of the photochromic material, siloxane and curing agent is 2 to 5:10:1.

[0017] Preferably, the temperature of the heating and curing is 100-150° C., and the time is 10-60 minutes.

[0018] The present invention provides a lead ion-doped chloride perovskite photochromic film prepared by the above preparation method.

[0019] Beneficial effects of the present invention:

[0020] The lead ion doped chloride perovskite photochromic material provided by the present invention uses CsCdCl3 as a matrix, and introduces lead ions into it to destroy the original symmetry, thereby obtaining a chemical formula of CsCd 1-a Pb a Cl3 (where a is 0.003 to 0.1) is an inorganic halide perovskite material. This material can produce a very fast light response speed in seconds (different from the response speed of several minutes of conventional inorganic oxide color-changing materials) under the excitation of ultraviolet light or X-rays, resulting in a color change phenomenon. Under ultraviolet light irradiation, it shows a photochromic phenomenon with a color change rate of up to 35%, with outstanding color contrast. Under X-ray irradiation, it can show a photochromic phenomenon with a color change rate of 16%. An optical absorption band of 300 to 800 nm appears in the diffuse reflectance spectrum, which can be reversibly restored after heating. It is expected to be used in the fields of visual display, multi-level information encryption and storage technology.

[0021] Compared with oxide powders and glass ceramics, the preparation of the lead ion-doped chloride perovskite photochromic material of the present invention does not require high-temperature and high-pressure synthesis equipment. The preparation process is simple, the preparation temperature is low, and the synthesis process does not require isolation of water and oxygen. It is easy to prepare and obtain, and the resulting product has stable performance and significant advantages in large-scale production.

[0022] The photochromic material of the present invention can be compounded with organic silica gel to form a flexible film while maintaining good stability, and can be used in harsh climate environments to facilitate non-planar optical information writing and multi-dimensional information recording. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 CsCd of Example 1 0.99 Pb 0.01 X-ray diffraction results of Cl3;

[0024] Figure 2 This is the X-ray diffraction result of CsCdCl3 in Comparative Example 1;

[0025] Figure 3 The diffuse reflectance spectra of CsCdCl3 in Comparative Example 1 before and after UV irradiation for ten minutes;

[0026] Figure 4 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 without UV irradiation;

[0027] Figure 5 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after UV irradiation;

[0028] Figure 6 CsCd of Example 1 0.99 Pb 0.01 Comparison of the Cl3 film irradiated with 302nm UV light for 1 second and the unirradiated one;

[0029] Figure 7 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectra of Cl3 irradiated with ultraviolet light at a wavelength of 302 nm for 1 second, 1 minute, 5 minutes, 10 minutes, 20 minutes and 1 hour;

[0030] Figure 8 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after X-ray irradiation;

[0031] Figure 9 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectra of Cl3 after X-ray irradiation for 1 second, 1 minute, 5 minutes, 10 minutes, 20 minutes and 1 hour;

[0032] Figure 10 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after UV irradiation and subsequent heating recovery;

[0033] Figure 11 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after X-ray irradiation and subsequent heating recovery;

[0034] Figure 12 CsCd of Example 1 0.99 Pb 0.01 Thermogravimetric curve of Cl3 in the temperature range of 30-800℃;

[0035] Figure 13 CsCd of Example 1 0.99 Pb 0.01 The diffuse reflectance difference spectrum of Cl3 irradiated with ultraviolet light of wavelength 302nm for 1 hour;

[0036] Figure 14 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance difference spectrum of Cl3 irradiated under X-ray for 1 hour. DETAILED DESCRIPTION

[0037] The present invention provides a lead ion doped chloride perovskite photochromic material, the chemical composition of which is CsCd 1- a Pb a Cl3, wherein a is 0.003 to 0.1.

[0038] The present invention provides a method for preparing a lead ion-doped chloride perovskite photochromic material, comprising the following steps:

[0039] As described CsCd 1-a Pb a CsCl, CdCl2 and PbCl2 are mixed with an acid solution in a stoichiometric ratio of Cl3 to obtain a precursor mixture;

[0040] The precursor mixture is subjected to a hydrothermal reaction to obtain a lead ion-doped chloride perovskite photochromic material.

[0041] In the present invention, unless otherwise specified, the raw materials required for preparation are all commercially available products well known to those skilled in the art.

[0042] The present invention preferably mixes CsCl, CdCl2 and PbCl2 with an acid solution to obtain a CsCl solution, a CdCl2 solution and a PbCl2 solution, respectively; mixes the CdCl2 solution and the PbCl2 solution to obtain a mixed solution of the CdCl2 solution and the PbCl2 solution; and drops the CsCl solution into the mixed solution of the CdCl2 solution and the PbCl2 solution, stirring to obtain a precursor mixture.

[0043] In the present invention, the acid solution preferably includes a hydrochloric acid aqueous solution with a mass concentration of 20 to 36%, and further includes a hydrochloric acid aqueous solution with a mass concentration of 36%.

[0044] The present invention does not particularly limit the mass of the CsCl, CdCl2 and PbCl2 and the volume of the acid solution. In the embodiment, 1.6836 g of CsCl, 1.8148 g of CdCl2 and 0.0278 g of PbCl2 are preferably placed in a beaker, and 30 mL, 40 mL and 5 mL of a 36% hydrochloric acid aqueous solution are added, respectively, to obtain a CsCl solution, a CdCl2 solution and a PbCl2 solution, respectively.

[0045] The present invention preferably places the precursor mixture in a polytetrafluoroethylene liner of a hydrothermal reactor, then tightens the hydrothermal reactor to carry out a hydrothermal reaction, and naturally cools to room temperature after the reaction is complete. The reaction product is obtained by filtration, and the reaction product is washed and placed in an oven to dry overnight to obtain a lead ion-doped chloride perovskite photochromic material.

[0046] In the present invention, the temperature of the hydrothermal reaction is preferably 150 to 200° C., more preferably 180° C., and the time is preferably 10 to 24 hours, more preferably 12 to 24 hours.

[0047] In the present invention, the cleaning agent used for the cleaning preferably includes isopropyl alcohol, methanol or propanol; and the number of times of the cleaning is preferably 2 to 5 times, more preferably 3 times.

[0048] In the present invention, the drying temperature is preferably 60 to 80° C., more preferably 60° C., and the drying time is preferably 12 to 24 hours, more preferably 12 hours.

[0049] The present invention provides the use of the lead ion-doped chloride perovskite photochromic material or the lead ion-doped chloride perovskite photochromic material prepared by the above preparation method in anti-counterfeiting labels, optical storage, visual display or multi-level information encryption and storage.

[0050] The present invention provides a method for preparing a lead ion-doped chloride perovskite photochromic film, comprising the following steps:

[0051] The photochromic material, silicone and curing agent were mixed and poured into a self-made polytetrafluoroethylene mold, and then vented in a vacuum drying oven and heated for curing to obtain a photochromic material film.

[0052] The photochromic material is the lead ion-doped chloride perovskite photochromic material or the lead ion-doped chloride perovskite photochromic material prepared by the above preparation method.

[0053] In the present invention, the siloxane preferably includes ethylene-terminated long-chain dimethylsiloxane, and more preferably polydimethylsiloxane. The present invention does not specifically limit the type of curing agent, and any curing agent compatible with the siloxane can be used in the present invention. The siloxane and curing agent used in the embodiment of the present invention are preferably commercial polydimethylsiloxane Dow Corning SYLGARD 184, which is a set produced by Dow Corning.

[0054] In the present invention, the mass ratio of the photochromic material, the siloxane and the curing agent is preferably 2 to 5:10:1, more preferably 5:10:1.

[0055] In the present invention, the temperature of the heat curing is preferably 100 to 150° C., more preferably 125 to 150° C., and the time is preferably 10 to 60 minutes, more preferably 10 to 30 minutes.

[0056] In the present invention, the photochromic material film is formed into an elastic film in the mold and can be used independently without coating.

[0057] The present invention provides a lead ion-doped chloride perovskite photochromic film prepared by the above preparation method.

[0058] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1

[0060] According to CsCd 0.99 Pb 0.01 Cl3, respectively weighing 1.6836 g CsCl, 1.8148 g CdCl2, and 0.0278 g PbCl2 into a beaker, and adding 30 mL, 40 mL, and 5 mL of a 36% hydrochloric acid aqueous solution, respectively, to obtain a CsCl solution, a CdCl2 solution, and a PbCl2 solution; mixing the CdCl2 solution and the PbCl2 solution to obtain a mixed solution of the CdCl2 solution and the PbCl2 solution; adding the CsCl solution dropwise to the mixed solution containing the CdCl2 solution and the PbCl2 solution, and stirring with a magnetic stirrer for 30 minutes to obtain a precursor mixture;

[0061] The precursor mixture was placed in the polytetrafluoroethylene lining of the hydrothermal reactor, and then the hydrothermal reactor was tightened and transferred to an oven at 180°C for reaction for 12 hours. After the reaction was complete, it was naturally cooled to room temperature and the reaction product was obtained by filtration. The reaction product was rinsed with isopropyl alcohol three times and then dried in an oven at 60°C for 12 hours to obtain the lead ion-doped chloride perovskite photochromic material CsCd 0.99 Pb 0.01 Cl3.

[0062] Comparative Example 1

[0063] According to the stoichiometric ratio of CsCdCl3, 1.6836 g of CsCl and 1.8332 g of CdCl2 were weighed and placed in a beaker, and 30 mL and 40 mL of a 36% aqueous hydrochloric acid solution were added, respectively, to obtain a CsCl solution and a CdCl2 solution, respectively. Subsequently, the hydrochloric acid solution containing CsCl was slowly added dropwise to the CdCl2 solution and stirred for 30 minutes using a magnetic stirrer to obtain a mixture.

[0064] The mixture was placed in the polytetrafluoroethylene liner of the hydrothermal reactor, and then the hydrothermal reactor was tightened and transferred to an oven at 180°C for reaction for 12 hours. After the reaction was complete, it was naturally cooled to room temperature and the reaction product was obtained by filtration. The reaction product was rinsed with isopropanol three times and then placed in a 60°C oven for drying for 12 hours to obtain an undoped pure CsCdCl3 sample.

[0065] Performance Testing

[0066] 1) The crystal phases of the perovskite material samples prepared in Example 1 and Comparative Example 1 were identified and analyzed, and the relevant powder X-ray diffraction results are shown in Figure 1 and Figure 2 , Figure 1 CsCd of Example 1 0.99 Pb 0.01 The X-ray diffraction results of Cl3 are shown in Figure 2. Figure 2 This is the X-ray diffraction result of CsCdCl3 in Comparative Example 1;

[0067] like Figure 1 and Figure 2 As shown, the standard card of CsCdCl3 confirms the pure phase characteristics of the synthesized material. Figure 1 and Figure 2 , which shows that lead ion doping of CsCdCl3 perovskite material does not produce crystal phase changes.

[0068] 2) The reflectivity of the perovskite material samples prepared in Example 1 and Comparative Example 1 before and after ultraviolet light irradiation was measured using an ultraviolet-visible spectrophotometer to illustrate the occurrence and extent of photochromism. Figures 3-5 :in Figure 3 The diffuse reflectance spectra of CsCdCl3 in Comparative Example 1 before and after UV irradiation for ten minutes are shown. Figure 4 CsCd of Example 1 0.99 Pb 0.01 The diffuse reflectance spectrum of Cl3 without UV irradiation, Figure 5 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after UV irradiation;

[0069] Depend on Figure 3 It can be seen that the sample prepared in Comparative Example 1 did not show obvious photochromic effect before and after ultraviolet irradiation;

[0070] Depend on Figure 4 and Figure 5 It can be seen that the sample prepared in Example 1 undergoes obvious light absorption phenomenon in the range of 300nm to 800nm after being irradiated with ultraviolet light, which manifests as photochromism.

[0071] 3) The sample prepared in Example 1 was irradiated with ultraviolet light of 302 nm wavelength for 1 s, and the changes in the appearance of the sample were observed. Figure 6 , Figure 6 CsCd of Example 1 0.99 Pb 0.01 Comparison of the Cl3 film irradiated with 302nm UV light for 1 second and the unirradiated one;

[0072] Depend on Figure 6 It can be seen that the sample prepared in Example 1 can produce an extremely fast light response speed in seconds under ultraviolet excitation.

[0073] 4) The samples prepared in Example 1 were irradiated with ultraviolet light of wavelength 302 nm for different time periods to explore the relationship between the degree of photochromism and irradiation time. The measured diffuse reflectance spectra showed Figure 7 , Figure 7 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectra of Cl3 irradiated with ultraviolet light at a wavelength of 302 nm for 1 second, 1 minute, 5 minutes, 10 minutes, 20 minutes and 1 hour;

[0074] Depend on Figure 7 It can be seen that the increase of illumination time can enhance the degree of photochromism.

[0075] 5) X-ray irradiation was used to investigate the photochromic properties of the sample prepared in Example 1. The diffuse reflectance spectrum was shown in FIG. Figure 8 , Figure 8 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after X-ray irradiation;

[0076] Compare Figure 3 and Figure 8 It can be seen that Figure 8 It was demonstrated that X-ray irradiation could induce photochromism of the sample prepared in Example 1.

[0077] 6) The samples prepared in Example 1 were irradiated with X-rays for different time periods to explore the relationship between the degree of photochromism and irradiation time. The measured diffuse reflectance spectra were shown in FIG. Figure 9 , Figure 9 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectra of Cl3 after X-ray irradiation for 1 second, 1 minute, 5 minutes, 10 minutes, 20 minutes and 1 hour;

[0078] Depend on Figure 9 It can be seen that the increase of irradiation time can enhance the degree of photochromism.

[0079] 7) The reversible photochromic performance of the sample prepared in Example 1 was verified by heating the sample which was photochromic due to UV light or X-ray irradiation. The diffuse reflectance spectrum was shown in FIG. Figure 10 and Figure 11 :in Figure 10 CsCd of Example 1 0.99 Pb 0.01The diffuse reflectance spectrum of Cl3 after UV irradiation and subsequent heating recovery, Figure 11 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance spectrum of Cl3 after X-ray irradiation and subsequent heating recovery;

[0080] Depend on Figure 10 and Figure 11 It can be seen that under the condition of 120° C., the sample prepared in Example 1 that has undergone photochromism can be restored to a colorless state and can be repeatedly operated, confirming its reversible photochromic performance.

[0081] 8) The thermal stability of the sample prepared in Example 1 was analyzed by thermogravimetric method to illustrate the reliability of the method of restoring the original state by heating: The sample prepared in Example 1 was subjected to thermogravimetric curve test in the temperature range of 30-800°C. The results are shown in FIG. Figure 12 , Figure 12 CsCd of Example 1 0.99 Pb 0.01 Thermogravimetric curve of Cl3 in the temperature range of 30-800℃;

[0082] Depend on Figure 12 It can be seen that the sample remains stable before 500°C and no weight loss occurs, which reveals the reliability of the heating method (120°C) to cause the sample prepared in Example 1 to fade.

[0083] 9) The diffuse reflectance difference spectrum of the sample of Example 1 after irradiation with 302nm ultraviolet light for 1 hour was obtained by subtracting the diffuse reflectance spectrum before irradiation. The results are shown in FIG. Figure 13 and Figure 14 :in Figure 13 CsCd of Example 1 0.99 Pb 0.01 The diffuse reflectance difference spectrum of Cl3 irradiated with ultraviolet light of wavelength 302nm for 1 hour, Figure 14 CsCd of Example 1 0.99 Pb 0.01 Diffuse reflectance difference spectrum of Cl3 irradiated under X-ray for 1 hour;

[0084] Depend on Figure 13 It can be seen that the sample of Example 1 can obtain a maximum color change rate of 35% by ultraviolet irradiation; Figure 14 It can be seen that the sample of Example 1 can obtain a maximum color change rate of 16% through X-ray irradiation.

[0085] As can be seen from the above embodiments, the present invention provides a lead ion-doped chloride perovskite photochromic material, a preparation method and application thereof, a lead ion-doped chloride perovskite photochromic film and a preparation method thereof. The inorganic perovskite photochromic material exhibits a photochromic phenomenon with a color change rate of up to 35% under ultraviolet light irradiation and a photochromic phenomenon with a color change rate of up to 16% under X-ray irradiation, and can be applied to anti-counterfeiting labels or optical storage fields.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A lead ion-doped chloride perovskite photochromic material, characterized in that: The chemical composition is CsCd 1- a Pb a Cl3, wherein a is 0.003 to 0.

1.

2. The method for preparing the lead ion-doped chloride perovskite photochromic material according to claim 1, characterized in that: The following steps are involved: As described CsCd 1-a Pb a CsCl, CdCl2 and PbCl2 are mixed with an acid solution in a stoichiometric ratio of Cl3 to obtain a precursor mixture; The precursor mixture is subjected to a hydrothermal reaction to obtain a lead ion-doped chloride perovskite photochromic material.

3. The preparation method according to claim 2, characterized in that The acid solution includes a hydrochloric acid aqueous solution with a mass concentration of 20 to 36%.

4. The preparation method according to claim 2, characterized in that The temperature of the hydrothermal reaction is 150-200°C and the time is 10 ～ 24h.

5. The preparation method according to claim 2, characterized in that After the hydrothermal reaction, the obtained product is sequentially washed and dried; the washing agent used for the washing includes isopropanol, methanol or propanol, the drying temperature is 60 to 80° C., and the drying time is 12 to 24 hours.

6. Use of the lead ion-doped chloride perovskite photochromic material according to claim 1 or the lead ion-doped chloride perovskite photochromic material prepared by the preparation method according to any one of claims 2 to 5 in anti-counterfeiting labels, optical storage, visual display or multi-layer information encryption.

7. A method for preparing a lead ion-doped chloride perovskite photochromic film, characterized in that: The following steps are involved: The photochromic material, silicone and curing agent are mixed and poured into a mold, and then vented and heated to cure in sequence to obtain a photochromic material film; The photochromic material is the lead ion-doped chloride perovskite photochromic material according to claim 1 or the lead ion-doped chloride perovskite photochromic material prepared by the preparation method according to any one of claims 2 to 5.

8. The preparation method according to claim 7, characterized in that The siloxane includes ethylene-terminated long-chain dimethylsiloxane; the mass ratio of the photochromic material, the siloxane and the curing agent is 2 to 5:10:

1.

9. The preparation method according to claim 7, characterized in that The temperature of the heating curing is 100-150° C., and the time is 10-60 minutes.

10. The lead ion-doped chloride perovskite photochromic film prepared by the preparation method according to any one of claims 7 to 9.

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