Doped chiral metal halide material with light-induced circular polarization luminescence and preparation method and application thereof

Abstract

The invention relates to the technical field of organic and inorganic hybrid functional materials, in particular to a doped chiral metal halide material with light-induced circular polarization luminescence and a preparation method and application of the doped chiral metal halide material, the chemical formula of the doped chiral metal halide material is L2BnC1-nX4, and the value of n is 0 lt; n is less than 1. The fluorescence quantum yield of a film sample is remarkably improved by using a transition metal ion or rare earth ion doping method. According to the invention, the plug splitting energy in the chiral metal halide is adjusted, so that the chiral optical property of the film material is remarkably improved. The preparation process of the chiral metal halide thin film is simple, the thin film does not need to be prepared after a single crystal material is obtained through a harsh single crystal preparation method, and the material composition and the doping proportion can be easily adjusted according to the requirements of material properties. The invention provides a feasible way for regulating and controlling the chiral optical property of the chiral metal halide by doping transition metal ions or rare earth ions.

Description

Technical Field

[0001] The present invention relates to the technical field of organic-inorganic hybrid functional materials, and particularly relates to a doped chiral metal halide material with photoinduced circularly polarized luminescence, a preparation method thereof, and an application thereof. Background Art

[0002] The development of circularly polarized light sources plays a crucial role in modern display industries and future technical fields, including 3D displays, quantum computing, sensing technologies, and encrypted communications, etc. However, the prospects of these emerging photon devices depend on how to efficiently generate circularly polarized photons with high purity, that is, to obtain left-handed / right-handed circularly polarized light with a high dissymmetry factor. Currently, some progress has been made in the research fields of chiral organic fluorescent materials and chiral lanthanide complexes. However, it is still a challenge to achieve circularly polarized fluorescence with a high dissymmetry factor. In addition, due to different dipole selection rules of the electric dipole moment and the magnetic dipole moment, there is a trade-off relationship between the photoluminescence quantum yield and the luminescence dissymmetry factor.

[0003] In contrast, chiral metal halide materials have great potential as circularly polarized light source materials. They have characteristics such as high luminescence dissymmetry factors, excellent fluorescence quantum yields, narrow emission spectra, and easily adjustable emission spectra. By introducing chiral organic ligands into the metal halide hybrid framework, the introduction of chirality in the structure of metal halide materials can be achieved, enabling the materials to possess chiral optical properties such as circular dichroism absorption (CD) and circularly polarized luminescence (CPL). Although some breakthroughs have been made in the circularly polarized luminescence dissymmetry factor, it is still challenging to prepare thin films of chiral metal halide materials with high fluorescence quantum yields, and the process is complex and time-consuming. The preparation methods reported in many works require the use of a strict and time-consuming single crystal preparation process. In addition, fast exciton quenching and a high density of defect states at room temperature result in a low radiative recombination rate of chiral metal halides. When chiral metal halide materials are fabricated into thin films, they exhibit a very low fluorescence quantum yield (<3%), which limits their application in the preparation of high-performance circularly polarized luminescence devices and other practical scenarios. Therefore, careful material synthesis design and defect engineering may be the key to improving their luminescence yield and luminescence dissymmetry factor. At the same time, the development of a fast and high-quality preparation method for chiral metal halide thin films is also crucial for the future application of this material. Summary of the Invention

[0004] One of the objectives of the present invention is to provide a doped chiral metal halide material with photoinduced circularly polarized luminescence. Through energy transfer between a chiral metal halide host and transition metal ions or rare earth ions, the fluorescence quantum yield of the thin film sample is significantly improved.

[0005] Another object of the present invention is to provide a method for preparing a doped chiral metal halide material with photoluminescence circular polarization. The preparation process is simple and easy to adjust. By doping with transition metal ions or rare earth ions, the Zeeman splitting energy in the chiral metal halide is adjusted, so that the chiral optical properties of the prepared material are significantly improved.

[0006] A third object of the present invention is to provide an application of a doped chiral metal halide material with photoluminescence circular polarization.

[0007] The solution adopted by the present invention to achieve one of the objects is: a doped chiral metal halide material with photoluminescence circular polarization, and the chemical formula of the doped chiral metal halide material is L 2 B n C 1-n X 4 ;

[0008] wherein L is at least one of R / S-(+)-α-methylbenzylamine, R / S-(+)-α-phenylethylamine, R / S-β-methylphenethylamine, R / S-(+)-1-phenylpropylamine, R / S-(+)-1-1-naphthylethylamine, R / S-(-)-1-2-naphthylethylamine, R / S-1-(2-bromophenyl)-ethylamine, R / S-1-(3-bromophenyl)-ethylamine, R / S-1-(4-bromophenyl)-ethylamine, R / S-2-octylamine, B is selected from at least one of 2+ Pb 2+ and Sn 2+ C is selected from at least one of Mn 2+ Zn 2+ Cd 2+ Ni 2+ Cu 2+ Co 3+ Yb 3+ Er 3+ Dy 3+ Tb 3+ Eu 3+ Sm 3+ Ce

[0009] L is a monovalent chiral ammonium halide.

[0010] Preferably, when the thin film of the doped chiral metal halide is excited by light with a wavelength of 200-400 nm, there is photoluminescence circular polarization.

[0011] Preferably, when the powder of the doped chiral metal halide is excited by light with a wavelength of 200-400 nm, there is photoluminescence circular polarization.

[0012] The second solution adopted to achieve the object of the present invention is: A preparation method of the doped chiral metal halide material with photoluminescence circular polarization

[0013] A. When the doped chiral metal halide material with photoluminescence circular polarization is a thin film, it includes the following steps:

[0014] Step A1: Dissolve the halide salts of L, B, and C in a solvent to form a precursor solution;

[0015] Step A2: Spin-coat the precursor solution obtained in step 1 onto the surface of the substrate in an inert gas atmosphere, and obtain the doped chiral metal halide material with photoluminescence circular polarization through thermal annealing;

[0016] B. When the doped chiral metal halide material with photoluminescence circular polarization is a powder, it includes the following steps:

[0017] B1: Add the salts of B and C to a solvent in a certain proportion, and then perform vacuum degassing;

[0018] B2: Raise the temperature under vacuum degassing conditions to dissolve all the solutes, then add the L raw material and flush in an inert gas;

[0019] B3: Add trimethylhalosiloxane at a certain temperature and immediately quench the reaction in an ice bath;

[0020] B4: Wash and dry the product obtained in step B3 to obtain the doped chiral metal halide powder with photoluminescence circular polarization.

[0021] Preferably, in step A1, in the precursor solution, the molar ratio of L ions to the sum of B ions and C ions is 2:1, the molar ratio of B to C is 1:0.1 - 4, the total concentration of the precursor solution is 0.6 - 1.2 M, and the solvent is a polar solvent.

[0022] Preferably, the solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone.

[0023] Preferably, in step A2, the annealing temperature is 100 - 120 °C, and the annealing time is 5 - 20 min.

[0024] Preferably, in step B1, the salts of B and C are respectively any one or several of the acetates, nitrates, oleates, or carbonates of B or C, the molar ratio of B to C is 1:0.1 - 4, the solvent is a mixed solvent prepared by mixing octadecene and oleic acid in a volume ratio of 5 - 10:1, and the total concentration of B ions and C ions in octadecene is 0.4 - 1.0 M.

[0025] Preferably, in the step B2, the dissolution temperature is 100 - 120 °C, and the molar ratio of L ions to the sum of B ions and C ions is 2:1.

[0026] Preferably, in the step B3, after heating to 140 - 150 °C, trimethylhalosiloxane is added, and the volume ratio of the added trimethylhalosiloxane to L is 150 - 200:100 - 200.

[0027] The solution adopted to achieve the third object of the present invention is: an application of the doped chiral metal halide material with circularly polarized luminescence, which is applied to the fields of circularly polarized light-emitting diodes, circularly polarized light detectors, chiral sensing, or asymmetric photocatalysis.

[0028] The present invention has the following advantages and beneficial effects:

[0029] (1) By using the method of transition metal doping, through the energy transfer between the chiral metal halide host and transition metal ions or rare earth ions, the fluorescence quantum yield of the thin film sample is significantly improved.

[0030] (2) By using the method of transition metal ion or rare earth ion doping, the splitting energy in the chiral metal halide is adjusted, so that the chiral optical properties of the thin film material are significantly improved.

[0031] (3) The preparation process of the chiral metal halide thin film in the present invention is simple. It is not necessary to first obtain a single crystal material through a strict single crystal preparation method and then prepare the thin film. The material composition and doping ratio can be easily adjusted according to the needs of the material properties.

[0032] (4) The present invention provides a feasible way to regulate the chiral optical properties of chiral metal halides by doping transition metal ions or rare earth ions, promotes the development of chiral metal halides, and has frontier value in a series of applications such as circularly polarized light-emitting diodes, circularly polarized light detectors, chiral sensing, and asymmetric photocatalysis. Description of the Drawings

[0033] Figure 1 Absorption spectrum and structural formula of R-3BrMBA:Br salt prepared in Example 1 of the present invention;

[0034] Figure 2 CD circular dichroism absorption spectrum of R-3BrMBA:Br salt prepared in Example 1 of the present invention;

[0035] Figure 3 R-3BrMBA prepared in Example 1 of the present invention 2 PbBr 4 and R-3BrMBA 2 Pb x Mn1-x Br 4 Absorption spectrum of

[0036] Figure 4 R-3BrMBA prepared in Example 1 of the present invention 2 PbBr 4 and R-3BrMBA 2 Pb x Mn 1-x Br 4 CD circular dichroism absorption spectrum of

[0037] Figure 5 R-3BrMBA prepared in Example 1 of the present invention 2 PbBr 4 and R-3BrMBA 2 Pb x Mn 1-x Br 4 Fluorescence images of the thin film under normal light and under 365 nm LED excitation

[0038] Figure 6 R-3BrMBA prepared in Example 1 of the present invention 2 PbBr 4 and R-3BrMBA 2 Pb x Mn 1-x Br 4 Fluorescence emission spectrum of

[0039] Figure 7 R-3BrMBA prepared in Example 1 of the present invention 2 PbBr 4 and R-3BrMBA 2 Pb x Mn 1-x Br 4 Photoluminescence asymmetry factor of

[0040] Figure 8 R-3BrMBA prepared in Example 2 of the present invention 2 Pb x Mn 1-x Br 4 Fluorescent powder of

[0041] Figure 9 R-3BrMBA prepared in Example 2 of the present invention 2 Pb x Mn 1-x Br 4 Fluorescence quantum yield of the thin film

[0042] Figure 10R-3BrMBA prepared in Example 2 of the present invention 2 PbBr 4 and R-3BrMBA 2 Pb x Mn 1-x Br 4 XRD diffraction patterns Detailed implementation manners

[0043] To better understand the present invention, the following examples are further descriptions of the present invention, but the content of the present invention is not limited to the following examples only.

[0044] The present invention provides a method for preparing a doped chiral metal halide thin film, and the steps are as follows:

[0045] a. Prepare a precursor solution: Mix the halide salts of L, B, and C in a molar ratio of 2:n:1-n (0 < n < 1) in a polar solvent, and stir at 60-80 °C to obtain a precursor solution; the polar solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone;

[0046] b. Prepare a chiral metal halide thin film: Spin-coat the precursor solution on a UVO-treated substrate under an inert gas atmosphere, and obtain a chiral metal halide thin film with circularly polarized luminescence under 365 nm LED excitation through a thermal annealing process. The annealing temperature is 100-120 °C, and the annealing time is 5-20 min.

[0047] In addition, the present invention also proposes a method for preparing the above-mentioned doped chiral metal halide powder, including the following steps:

[0048] a. Add any one or several of the acetates, nitrates, oleates, or carbonates of B and C to a mixed solvent of octadecene and oleic acid in a molar ratio of 1:0.1-4, and then perform vacuum degassing. The volume ratio of octadecene to oleic acid is 10:1-5:1;

[0049] b. Heat up to 100-120 °C under vacuum degassing conditions to dissolve all solutes, then add the L raw material, degas and heat up to 140-150 °C and flush in an inert gas;

[0050] c. Add TMS-X (trimethylhalosiloxane), and then immediately place the reaction device in an ice bath to quench the reaction. The obtained product is washed several times with a non-polar solvent and dried. Finally, a chiral metal halide powder with circularly polarized luminescence under 365 nm LED excitation is obtained.

[0051] Example 1:

[0052] In this example, a chiral metal halide thin film doped with Mn 2+ and R-3BrMBA 2 PbBr 4 with circularly polarized luminescence properties was prepared. The specific implementation steps are as follows:

[0053] (1) Synthesis of R-3BrMBA:Br salt

[0054] Step 1: Take 13 mL of hydrobromic acid, 30 mL of absolute ethanol, and 10 mL of R-3BrMBA in a 100 mL three-necked flask, place it in an ice bath, and react for more than 4 h under the protection of an inert atmosphere.

[0055] Step 2: Remove the unreacted ethanol, hydrobromic acid, and R-3BrMBA in the crude product in Step 1 through a rotary evaporator to obtain an orange-yellow crude product salt.

[0056] Step 3: Add 5 mL of absolute ethanol to dissolve the product salt completely under the condition of an 80 °C oil bath, and then quickly precipitate the product salt by adding 15 mL of diethyl ether while it is hot.

[0057] Step 4: Filter the product salt by suction to remove the excess diethyl ether, and then repeat Step 3 multiple times until the upper layer of diethyl ether is colorless and transparent.

[0058] Step 5: Place the salt recrystallized multiple times in a 50 °C vacuum drying oven for R-3BrMBA:Br and dry it for 2 hours to finally obtain pure white R-3BrMBA:Br. Take 10 mg of the obtained R-3BrMBA:Br salt and dissolve it in 100 μL of methanol, and then spin-coat it on a glass slide. The absorption and CD results measured by a circular dichroism absorption spectrometer are as Figure 1 and Figure 2 shown. It can be seen from Figure 1 that the sample shows strong absorption before 240 nm. Figure 2 In, the sample shows a strong circular dichroism absorption response at 240 nm, indicating the successful synthesis of the R-3BrMBA:Br chiral ammonium halide salt.

[0059] (2) Preparation of R-3BrMBA 2 PbBr 4 thin film

[0060] Step 1: Take 224.8 mg of R-3BrMBA:Br and 145.8 mg of PbBr 2 and add them to 1 mL of ultra-dry DMF (N,N-dimethylformamide) solvent. Then place the solution on an 80 °C hot stage and stir overnight to completely dissolve the solute to obtain a precursor solution.

[0061] Step 2: Under an inert gas atmosphere, use a pipette to drop 80 μL of the precursor solution in step 1 onto the UVO-treated substrate surface and spin coat at 4000 rpm for 60 s.

[0062] Step 3: Place the sample on a 100°C hot plate for annealing for 5 minutes to obtain R-3BrMBA with white fluorescence under 365nm LED light. 2 PbB 4 film.

[0063] (3)(R-3BrMBA) 2 Pb x Mn 1-x Br 4 Thin film preparation

[0064] Step 1: Take 224.8 mg of R-3BrMBA:Br and 73.4 mg of PbBr 2 and 42.9 mg of MnBr 2 In 1 mL of DMF ultra-dry solvent, the solution was then placed on a hot plate at 80° C. and stirred overnight to completely dissolve the solute to obtain a precursor solution.

[0065] Step 2: Under an inert gas atmosphere, use a pipette to drop 80 μL of the precursor solution in step 1 onto the UVO-treated substrate surface and spin coat at 2000 rpm for 60 seconds.

[0066] Step 3: Place the sample on a 100°C hot plate for annealing for 5 minutes to obtain bright orange-yellow fluorescence (R-3BrMBA) under 365nm LED light. 2 Pb x Mn 1-x Br 4 film.

[0067] pass Figure 3 The absorption spectrum of the doped sample shows that the exciton peak undergoes an obvious red shift, indicating that the Mn 2+ The doping of 2 changes the band structure of the material. Through CD circular dichroism absorption spectroscopy, Figure 4 The doped sample showed a higher CD response at the exciton absorption peak, increasing from 5 millidegrees to 190 millidegrees, indicating that doping can significantly enhance the chiral structural deformation in the material. Figure 5 Film physical picture and Figure 6 From the fluorescence emission spectrum, we can see that the sample before doping exhibits a weak warm white fluorescence, while the sample after doping exhibits a bright orange-yellow fluorescence, which is due to the Mn 2+ The characteristic emission of Mn 2+ The successful doping of can significantly improve the emission performance of chiral two-dimensional perovskite. Through the photoinduced circularly polarized luminescence asymmetry factor test,Figure 7 in which, (R-3BrMBA) 2 Pb x Mn 1-x Br 4 exhibits a higher luminescence asymmetry factor. After doping, g lum is increased from the original 0.02 to 0.13. Therefore, this strategy can significantly improve the fluorescence quantum yield and luminescence asymmetry factor of chiral metal halides.

[0068] Example 2

[0069] In this example, a chiral metal halide powder doped with Mn 2+ and R-3BrMBA 2 PbBr 4 with circularly polarized luminescence properties was prepared. The specific implementation steps are as follows:

[0070] Step 1: Take 34.6 mg of manganese acetate and 65.1 mg of lead acetate in a three-necked flask, add 10 mL of octadecene and 1 mL of oleic acid, and degas under vacuum at room temperature for 30 min.

[0071] Step 2: Heat the reaction system to 120 °C under degassing conditions, and then degas for 60 minutes to dissolve both lead acetate and manganese acetate.

[0072] Step 3: Add 200 μL of R-3BrMBA, degas for 5 minutes, and then immediately inject an inert gas to keep the reaction system under an inert gas atmosphere for 30 minutes.

[0073] Step 4: Heat the reaction system to 140 °C, then add 200 μL of TMS-Br, and immediately place the reaction system in an ice-water bath for quenching. At this time, the three-necked flask shows bright orange-red fluorescence under 365 nm LED irradiation.

[0074] Step 5: Centrifuge the crude reaction product, discard the upper layer solution, add toluene to wash the lower layer solid, and repeat three times. Put the obtained product into a vacuum drying oven for drying to finally obtain a white powder sample.

[0075] Figure 8 As can be seen, the obtained doped powder sample exhibits strong orange-red fluorescence under 365 nm ultraviolet lamp irradiation. Figure 9 The fluorescence quantum yield test shows that the PLQY of the doped powder sample is as high as 29.7%. The powder XRD test shows that the Mn 2+ powder sample exhibits a crystal structure similar to that of the undoped sample.

[0076] The above are the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A doped chiral metal halide material having photoinduced circularly polarized luminescence, characterized in that: The chemical formula of the doped chiral metal halide material is L2B n C 1-n X4; Wherein L is at least one of R / S-(+)-α-methylbenzylamine, R / S-(+)-α-phenylethylamine, R / S-β-methylphenylethylamine, R / S-(+)-1-phenylpropylamine, R / S-(+)-1-1-naphthylethylamine, R / S-(-)-1-2-naphthylethylamine, R / S-1-(2-bromophenyl)-ethylamine, R / S-1-(3-bromophenyl)-ethylamine, R / S-1-(4-bromophenyl)-ethylamine, and R / S-2-octylamine, and B is selected from Pb 2+ and Sn 2+ At least one of, C is selected from Mn 2+ , Zn 2+ , Cd 2+ , Ni 2+ , Cu 2+ ,Co 2+ , Yb 3+ , Er 3+ ,Dy 3+ , Tb 3+ ,Eu 3+ , Sm 3+ , Ce 3+ At least one of, X is selected from at least one of Cl, Br and I, and the value of n is 0 <n<1。 2. The doped chiral metal halide material having photoinduced circularly polarized luminescence according to claim 1, characterized in that: The chiral metal halide-doped film emits photoinduced circular polarization light under the excitation of light in the range of 200-400nm.

3. The doped chiral metal halide material having photoinduced circularly polarized luminescence according to claim 1, characterized in that: The chiral metal halide-doped powder emits photoinduced circular polarization light under the excitation of light in the range of 200-400nm.

4. A method for preparing a doped chiral metal halide material having photoinduced circularly polarized luminescence according to any one of claims 1 to 3, characterized in that: A. When the doped chiral metal halide material having photoinduced circularly polarized luminescence is a thin film, the method comprises the following steps: Step A1: dissolving halide salts of L, B and C in a solvent to form a precursor solution; Step A2: spin-coating the precursor solution obtained in step 1 onto the surface of the substrate in an inert gas atmosphere, and obtaining a doped chiral metal halide material having photoinduced circularly polarized luminescence by thermal annealing; B. When the doped chiral metal halide material having photoinduced circularly polarized luminescence is a powder, the method comprises the following steps: B1: Add salt B and salt C to the solvent in a certain proportion, and then perform vacuum degassing; B2: Raise the temperature under vacuum degassing conditions to dissolve all the solutes, then add L raw material and flush with inert gas; B3: Add trimethyl halogen siloxane at a certain temperature and immediately quench the reaction in an ice bath; B4: The product obtained in step B3 is washed and dried to obtain a doped chiral metal halide powder having photoinduced circularly polarized luminescence.

5. The preparation method according to claim 4, characterized in that: In the step A1, in the precursor solution, the molar ratio of L ions to the sum of B ions and C ions is 2:1, the molar ratio of B to C is 1:0.1-4, the total concentration of the precursor solution is 0.6-1.2M, and the solvent is a polar solvent.

6. The preparation method according to claim 4, characterized in that: In the step A2, the annealing temperature is 100-120° C., and the annealing time is 5-20 min.

7. The preparation method according to claim 4, characterized in that: In the step B1, the B salt and the C salt are any one or more of the acetate, nitrate, oleate or carbonate of B or C, respectively, the molar ratio of B to C is 1:0.1-4, the solvent is a mixed solvent of octadecene and oleic acid prepared in a volume ratio of 5-10:1, and the total concentration of B ions and C ions in octadecene is 0.4-1.0M.

8. The preparation method according to claim 4, characterized in that: In the step B2, the dissolution temperature is 100-120° C., and the molar ratio of L ions to the sum of B ions and C ions is 2:

1.

9. The preparation method according to claim 4, characterized in that: In the step B3, after heating to 140-150° C., trimethyl halogen siloxane is added, and the volume ratio of the added trimethyl halogen siloxane to L is 150-200:100-200.

10. An application of a doped chiral metal halide material having photoinduced circularly polarized luminescence as claimed in any one of claims 1 to 3, characterized in that: It is applied in the fields of circularly polarized light emitting diodes, circularly polarized light detectors, chiral sensing or asymmetric photocatalysis.

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