A chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence performance and a preparation method and application thereof

Abstract

The application belongs to the technical field of optical functional materials and organic-inorganic hybrid materials, and particularly relates to a preparation method and application of a chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence. 1‑x Sb x )Cl6, wherein 0 < x < 0.2, which is composed of chiral organic cations and isolated metal halide octahedrons to form a zero-dimensional structure. A hydrogen bond network formed between the chiral organic cations and the inorganic octahedrons induces chiral lattice distortion of the inorganic framework and constructs a chiral crystal field, thereby realizing synergistic regulation of self-trapped exciton emission and chiral optical response. The obtained material exhibits high-efficiency luminescence and significant circularly polarized luminescence characteristics in the near-infrared region, has high photoluminescence quantum efficiency and a circularly polarized luminescence asymmetry factor, is environmentally friendly and low-toxic, and a near-infrared circularly polarized luminescence device constructed based on the material can be applied to the fields of optical anti-counterfeiting, information encryption, near-infrared imaging, biological detection and optoelectronic devices.

Description

Technical Field

[0001] This invention belongs to the technical field of optical functional materials and organic-inorganic hybrid materials, specifically relating to a chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties, its preparation method, and its application. Background Technology

[0002] Near-infrared circularly polarized luminescent (NIR CPL) materials have significant applications in chiral bioimaging, information encryption, optical communication, and optoelectronic devices. However, these materials generally face an inherent trade-off between luminescence efficiency and chiral optical response, making it difficult to simultaneously achieve high photoluminescence quantum efficiency (PLQY) and high circularly polarized luminescence asymmetry factor (|g|). lum This severely restricts its practical application.

[0003] In recent years, zero-dimensional organic-inorganic hybrid metal halides have demonstrated unique advantages in achieving high-efficiency luminescence due to their isolated octahedral metal halide structure and strong electron-phonon coupling characteristics. These materials readily form self-trapped excitons (STEs), enabling broadband luminescence with large Stokes shifts, providing a potential pathway for achieving efficient near-infrared luminescence. Furthermore, by introducing chiral organic cations, a chiral structural environment can be constructed within the crystal, thereby endowing the material with NIR CPL properties.

[0004] However, existing strategies for achieving NIR CPL largely rely on specific material systems or luminescent centers, lacking universality and making it difficult to simultaneously control the coupling relationship between exciton localization behavior and chiral optical response. Furthermore, the control of material structure mainly focuses on compositional design, with limited research on lattice micro-distortions and their impact on luminescence and chiral properties.

[0005] Studies have shown that lattice distortion plays a crucial role in modulating luminescence performance and chiral optical properties. On the one hand, lattice distortion can enhance electron-phonon coupling and promote exciton localization, thereby achieving a redshift in emission and improved efficiency. On the other hand, structural asymmetry helps to form a chiral crystal field, thus enhancing the NIR CPL response. However, an effective strategy is still lacking to achieve controllable tuning of lattice distortion and establish a direct correlation between it and NIR CPL performance.

[0006] Hydrogen bonding interactions, due to their excellent directionality and tunability, provide a feasible path for regulating crystal structure. By rationally designing organic molecular structures and constructing ordered hydrogen bond networks, controllable distortions can be induced in the inorganic framework. However, there are currently no reports on controlling the performance of NIR CPLs through hydrogen-induced lattice distortion.

[0007] Therefore, developing a material system that can achieve high-efficiency NIR CPL response through structural control is of great significance for promoting the application of such materials in the field of optoelectronics. Summary of the Invention

[0008] The purpose of this invention is to provide a chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties, so as to solve the problem that it is difficult to balance luminescence efficiency and chiral optical response in the existing near-infrared circularly polarized luminescence materials.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned material.

[0010] Another object of the present invention is to provide the application of the above-mentioned material in the fields of circularly polarized light-emitting devices and information encryption.

[0011] The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to the present invention has the chemical composition of: (R / SL)3(M 1-x M′ x Cl6, in, (1) L is a chiral organic amine cation containing an amino group (–NH2) and a halogen substituent, which can act as both a hydrogen bond donor and acceptor. (2) The chiral organic amine cation is an enantiomer of the R configuration or the S configuration; (3) M is In 3+ ; (4) M′ is Sb 3+ ; (5) x satisfies 0 <x ≤ 0.2; The material has a zero-dimensional structure, wherein the metal center (M) 1-x M′ x The isolated [In] is formed by the coordination of six chloride ions. 1-x Sb x Cl6] 3- Inorganic octahedral structural units, wherein each of the inorganic octahedral structural units is separated by the chiral organic cations; The chiral organic cations and the inorganic octahedral structural units form an asymmetric hydrogen bond network through N–H···Cl hydrogen bond interactions, thereby inducing chiral distortion of the octahedrons and constructing a chiral crystal field. The material generates self-captured exciton emission under ultraviolet or visible light excitation and exhibits near-infrared luminescence in the range of 700–800 nm, while also possessing circularly polarized luminescence characteristics.

[0012] The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to the present invention, wherein the chiral organic amine cation L is R / S-1-(4-chlorophenyl)ethylamine (R / S-ClMBA).

[0013] According to the present invention, the chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties, wherein the molar ratio of M to M' satisfies: M : M' = 80 : 20 to 95 : 5.

[0014] The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to the present invention, wherein the hydrogen bonding in the material is an N–H···Cl hydrogen bond, and the H···Cl distance in the hydrogen bond interaction is 2.3–2.8 Å, preferably 2.34–2.49 Å.

[0015] The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to the present invention is wherein the material is crystallized in a chiral orthorhombic crystal system space group C2221, and the R configuration and the S configuration are enantiomers of each other.

[0016] The present invention also provides a method for preparing the above-mentioned material, comprising the following steps: Chiral organic amine salts and metal halide precursors are dissolved in an acidic solvent to form a precursor solution, which is then heated to obtain the precursor. The obtained precursor was redissolved in a mixed solvent, and the chiral organic-inorganic hybrid metal halide single crystal material was obtained by heating, concentration, and static crystallization.

[0017] The present invention also provides applications of the above materials in the following fields: (1) near-infrared circularly polarized light-emitting devices, wherein the devices are circularly polarized light-emitting diodes or near-infrared light-emitting diodes; (2) optical anti-counterfeiting marks and information encryption patterns based on the difference in circularly polarized light emission; (3) near-infrared imaging or biological detection.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Existing near-infrared circularly polarized luminescent materials generally exhibit a high photoluminescence quantum efficiency (PLQY) and a high circular polarization luminescence asymmetry factor (|g). lum The present invention addresses the challenge of simultaneously achieving both high PLQY and a large |g|. By constructing a hydrogen-bonded induced asymmetric lattice distortion structure, this invention enhances electron-phonon coupling while introducing a chiral crystal field, thus realizing the synergistic control of self-trapped exciton emission and chiral optical response. lum The value breaks through the limitation of the existing system where luminous efficiency and chiral response are difficult to optimize in a unified manner.

[0019] 2. In existing near-infrared luminescent materials, high-efficiency luminescence is often difficult to achieve due to the strong non-radiative transition processes. This invention modulates lattice distortion through hydrogen bonding, enhances exciton localization, and stabilizes self-trapped exciton states, thereby effectively suppressing non-radiative transitions, increasing the radiative recombination probability, and enabling the material to achieve high-efficiency luminescence in the near-infrared region.

[0020] 3. Existing technologies for achieving near-infrared circularly polarized luminescence mostly rely on specific luminescent centers or empirical molecular design, lacking a clear structural control mechanism. This invention induces chiral distortion in inorganic metal halide octahedrons by constructing an ordered hydrogen bond network, establishing a chiral crystal field at the structural level, and achieving controllable adjustment of near-infrared circularly polarized luminescence performance, thus providing a universal structural design strategy.

[0021] 4. Existing technologies for controlling material properties largely rely on elemental doping or compositional changes, lacking precise means to control the crystal lattice microstructure. This invention utilizes the directionality and tunability of hydrogen bonding to effectively adjust the degree of lattice distortion, thereby establishing a correlation between crystal structure parameters and luminescence properties and chiral optical response, improving the controllability and scalability of material design.

[0022] 5. Existing high-performance metal halide luminescent materials are mostly lead-based systems, which pose potential toxicity and environmental risks, limiting their practical applications. This invention selects a lead-free metal halide system, using Sb-doped In-based metal halides as the inorganic framework. While ensuring excellent near-infrared circularly polarized luminescence performance, it effectively avoids the toxicity problems caused by lead, offering advantages such as environmental friendliness and green safety, making it more suitable for applications in optoelectronic devices and biological fields. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the synthesis method of chiral organic-inorganic hybrid metal halide single crystals with near-infrared circularly polarized luminescence properties in Example 1. Figure 2 This is a schematic diagram of the crystal structure of the R / S-NIR single crystal in Example 2; Figure 3 The powder X-ray diffraction pattern of the R / S-NIR crystal material in Example 2 and the powder X-ray diffraction pattern of the single crystal simulation are shown. Figure 4 The images shown are scanning electron microscope images and energy-dispersive X-ray spectra of the R-NIR single crystal in Example 2. Figure 5 The distribution of hydrogen bonds in the R-NIR single crystal in Example 2, Hirshfeld surface calculations, and two-dimensional fingerprint spectrum; Figure 6The photoluminescence excitation spectrum (PLE), photoluminescence spectrum (PL), and time-resolved photoluminescence spectrum (TRPL) of R-NIR in Example 3 are shown. Figure 7 The circular dichroism absorption spectrum (CD), circularly polarized emission spectrum (CPL), and emission asymmetry factor (|g) of R / S-NIR in Example 3 are shown. lum |); Figure 8 The photoluminescence quantum yield (PLQY) of R / S-NIR in Example 3; Figure 9 The electroluminescence spectrum and circular polarization emission spectrum of the near-infrared circularly polarized light-emitting device in Example 4 are shown. Figure 10 This is an image of an object captured by the near-infrared light-emitting device in Example 4. Detailed Implementation

[0024] This invention provides a zero-dimensional chiral organic-inorganic hybrid metal halide material, which is composed of chiral organic cations and inorganic metal halide octahedra, wherein the inorganic structural units are isolated octahedral structures, forming a zero-dimensional structure. The chiral organic cations and the inorganic metal halide octahedra form an asymmetric interaction network through hydrogen bonding, thereby inducing chiral distortion of the inorganic structure and forming a chiral crystal field.

[0025] Under the aforementioned structural effect, the material can form a stable self-captured exciton state and generate efficient light emission in the near-infrared region, while exhibiting significant circularly polarized light emission characteristics.

[0026] The technical problem solved by this application is that existing near-infrared circularly polarized luminescent materials are difficult to simultaneously achieve high photoluminescence quantum efficiency (PLQY) and a large circularly polarized luminescence asymmetry factor (|g). lum The near-infrared emission of light, along with its circularly polarized emission, limits its application in optoelectronic devices, information encryption, and biological imaging. Therefore, there is an urgent need to develop novel material systems that combine efficient near-infrared emission with excellent circularly polarized emission properties.

[0027] To address the above problems, this application has made the following technical improvements to the preparation method: 1. This application uses R / S-ClMBA organic amine salt as the organic component and InCl3 and SbCl3 as the inorganic components. A zero-dimensional organic-inorganic hybrid metal halide structure is formed through solution crystallization, constructing a structure consisting of isolated [InCl3]... 1-x Sb x Cl6] 3-The zero-dimensional structure composed of octahedrons enhances electron-phonon coupling and facilitates the formation of self-trapped excitons (STEs), thereby enabling broadband luminescence with a large Stokes shift. This provides a structural basis and possibility for materials to achieve efficient luminescence in the near-infrared region.

[0028] 2. This application first dissolves chiral organic amine salts and metal halide raw materials in hydrochloric acid to form a homogeneous solution system. After heat treatment to obtain a solid precursor, it is then redissolved in an ethanol / hydrochloric acid mixed solvent, and single crystals are grown by a combination of heating concentration and static crystallization. Compared with traditional direct crystallization methods, this method can effectively control the crystal growth process, enabling the organic cations and inorganic octahedra to achieve ordered arrangement during crystallization, and promoting the formation of N–H···Cl hydrogen bond networks. This improves the uniformity of the obtained crystal composition and structural integrity, thereby ensuring zero-dimensional [In 1-x Sb x Cl6] 3− The stable formation of the octahedral structure and the construction of an ordered asymmetric hydrogen bond network enhance the distortion of the inorganic octahedron, providing a structural basis for obtaining excellent near-infrared circularly polarized luminescence performance.

[0029] According to specific embodiments of the present invention, such as Figure 1 As shown, the preparation method of the above material includes the following steps: Chiral organic amine salts and metal halide precursors are dissolved in an acidic solvent to form a precursor solution, which is then heated to obtain the precursor. The obtained precursor was redissolved in a mixed solvent, and the chiral organic-inorganic hybrid metal halide single crystal material was obtained by heating, concentration, and static crystallization. Example 1: Preparation of R / S-NIR single crystal

[0030] In this embodiment, the chiral organic amine salt is (R / S)-1-(4-chlorophenyl)ethylamine hydrochloride (R / S-ClMBA-HCl), the metal halide precursor is indium trichloride (InCl3), the acidic solvent is antimony trichloride (SbCl3) hydrochloric acid (38% by mass), and the molar ratio of the chiral organic amine salt to the metal halide precursor is 3:1.

[0031] The method for preparing the chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties includes the following steps: Add 0.46 g R / S-ClMBA-HCl (2.4 mmol), 0.159 g InCl3 (0.72 mmol), and 0.018 g SbCl3 (0.08 mmol) to 2 mL of hydrochloric acid and stir at room temperature until completely dissolved to obtain a homogeneous and transparent solution.

[0032] The solution was then heated and evaporated at 100 °C until dry to obtain a solid precursor powder.

[0033] The obtained powder was added to a mixed solvent consisting of 1 mL ethanol and 0.5 mL hydrochloric acid, and stirred at room temperature to dissolve, thus obtaining a clear precursor solution.

[0034] The precursor solution was concentrated at 80 °C for 30 min, then removed and cooled to room temperature, and allowed to crystallize in a sealed environment for 3 days.

[0035] Finally, a colorless and transparent sheet-like single crystal was obtained, that is, an R / S-NIR material with an Sb doping ratio of 10% was prepared.

[0036] In this embodiment, by adjusting the feeding ratio of InCl3 to SbCl3, as shown in Table 1, R / S-NIR materials with Sb doping ratios of 5%, 10%, 15%, and 20% can be prepared. Here, the Sb doping ratio refers to the Sb... 3+ In total metal cations (Sb) 3+ +In 3+ The molar percentage of Sb in the near-infrared light emission is Sb / (Sb+In)×100%. When the Sb doping ratio is below 5%, the number of Sb-related luminescent centers in the system is insufficient, making it difficult to form effective near-infrared emission, resulting in low luminescence intensity (Table 2). When the Sb doping ratio is above 20%, it leads to an increase in lattice defects and non-radiative transitions, which also reduces the luminescence intensity. Therefore, 5%, 10%, 15%, and 20% doping ratios are preferred for preparing R / S-NIR materials.

[0037] Table 1 .

[0038] Taking R-NIR materials as an example, we compare PLQY and relative luminescence intensity under different Sb doping ratios.

[0039] Table 2 . Example 2: Structural and Compositional Characterization

[0040] The single-crystal X-ray diffraction results are shown in Table 3. This material crystallizes in an orthorhombic chiral space group C2221. The crystal structure is as follows: Figure 2 As shown, it consists of isolated [InCl6] and [SbCl6] octahedra, which are separated by chiral organic cations, forming a typical zero-dimensional structure.

[0041] Table 3 .

[0042] Powder X-ray diffraction test results are as follows Figure 3 As shown, the prepared crystal material has extremely high phase purity.

[0043] The microstructure and elemental distribution of the single crystal were obtained using scanning electron microscopy and energy-dispersive X-ray spectroscopy, such as... Figure 4 As shown, the obtained crystal exhibits a regular rod-like morphology, with Sb, In, and Cl elements uniformly distributed throughout the crystal. A schematic diagram of some hydrogen bonds in the crystal structure is shown below. Figure 5 As shown in Figure a, the results of Hirshfeld surface calculations are as follows: Figure 5 Figure b in the middle Figure 5 As shown in Figure c, hydrogen bonds account for as much as 97% of all weak interactions in the crystal structure. Example 3 Optical Performance

[0044] The photoluminescence excitation spectrum (PLE), photoluminescence spectrum (PL), and time-resolved photoluminescence spectrum (TRPL) of the prepared crystal material are as follows: Figure 6 As shown, it exhibits the strongest fluorescence emission peak under 340 nm ultraviolet light excitation, with a fluorescence lifetime of 2.05 μs. Its circular dichroism (CD) absorption spectrum, circularly polarized emission spectrum (CPL), and luminescence asymmetry factor (|g) are also described. lum |) as Figure 7 As shown, the R-configuration and S-configuration crystal materials exhibit mirror-symmetric circular dichroism absorption peaks at 340 nm, indicating a strong Cotton effect. Their circularly polarized emission peaks, located at 720 nm, also exhibit mirror symmetry. The g-values ​​of the R-configuration and S-configuration crystals... lum They are -1.83×10 -2 and 2.21×10 -2 Their PLQY were 86.1% and 83.7% respectively, such as Figure 8 As shown. Example 4: Fabrication, performance, and near-infrared imaging application verification of a near-infrared circular polarization device.

[0045] The R / S-NIR material was used as the emitting layer and encapsulated in a 365 nm ultraviolet LED chip to fabricate a near-infrared emitting device. For example... Figure 9 As shown, within the test current range of 10-100 mA, the peak intensity of the electroluminescence spectrum of this near-infrared light-emitting device gradually increases with increasing current. This near-infrared light-emitting device also exhibits significant circularly polarized emission characteristics, and its circularly polarized emission spectrum similarly displays a mirror-symmetric CPL signal.

[0046] like Figure 10As shown, the device was used as a near-infrared light source, and a near-infrared camera was used to photograph the target object. The results show that, when the device is in operation, the near-infrared camera can clearly acquire images of the target object, and the object's outline is clearly discernible. Furthermore, near-infrared imaging was performed using a human hand as the test subject. The results show that, under the illumination of the near-infrared light-emitting device of this invention, the outline of blood vessels inside the finger can be clearly identified.

[0047] The above results show that the material of the present invention has excellent near-infrared luminescence performance, and the near-infrared luminescent device constructed based on the material can achieve clear near-infrared imaging and can be used in the fields of night vision imaging and bio-imaging.

[0048] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only intended to help understand the method and core ideas of the present invention. For those skilled in the art, various equivalent substitutions or technical modifications can be made to the present invention without departing from the technical principles and core concepts of the present invention. All equivalent substitutions or modifications made based on the technical ideas of the present invention should fall within the protection scope of the claims of the present invention.

Claims

1. A chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties, characterized in that, The chemical composition of the chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties is: (R / SL)3(In 3+ 1-x Sb 3+ x Cl6, where, L is a chiral organic amine cation containing amino and halogen substituents; The chiral organic amine cation is an enantiomer of the R configuration or the S configuration; x satisfies 0 < x ≤ 0.2; The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties has a zero-dimensional structure, wherein the metal center (In) 3+ 1-x Sb 3+ x ) coordinates with six chloride ions to form isolated [In 1-x Sb x Cl6] 3- Inorganic octahedral structural units, wherein each of the inorganic octahedral structural units is isolated by the chiral organic cations; The chiral organic cations and the inorganic octahedral structural units form an asymmetric hydrogen bond network through N–H···Cl hydrogen bond interactions, thereby inducing chiral distortion of the octahedrons and constructing a chiral crystal field. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties is prepared by a method comprising the following steps: Chiral organic amine salts and metal halide precursors are dissolved in an acidic solvent to form a precursor solution, which is then heated to obtain the precursor. The obtained precursor was redissolved in a mixed solvent, and the chiral organic-inorganic hybrid metal halide single crystal material was obtained by heating, concentration, and static crystallization.

2. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to claim 1, characterized in that, The chiral organic amine cation L is R / S-1-(4-chlorophenyl)ethylamine.

3. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to claim 1, characterized in that, In 3+ With Sb 3+ The molar ratio is 80:20 to 95:

5.

4. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to claim 1, characterized in that, The H···CL distance in hydrogen bonding is 2.3–2.8 Å.

5. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to claim 1, characterized in that, The chiral organic amine salt is R / S-ClMBA, and the metal halide is InCl3 and SbCl3.

6. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to claim 1, characterized in that, The chiral organic amine salt and the metal halide precursor are dissolved in hydrochloric acid to form a precursor solution.

7. The chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties according to claim 1, characterized in that, The obtained precursor was redissolved in a mixed solvent of ethanol and hydrochloric acid, and the chiral organic-inorganic hybrid metal halide single crystal material was obtained by heating, concentration and static crystallization.

8. A method for preparing the chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties as described in claim 1, characterized in that, The method includes the following steps: A precursor solution is formed by dissolving a chiral organic amine salt and a metal halide precursor in an acidic solvent, and then heating the solution to obtain the precursor. The chiral organic amine salt is R / S-ClMBA, and the metal halide is InCl3 and SbCl3. The obtained precursor was redissolved in a mixed solvent, and the chiral organic-inorganic hybrid metal halide single crystal material was obtained by heating, concentration, and static crystallization.

9. The method according to claim 8, characterized in that, The molar ratio of the metal halide InCl3 to SbCl3 is 80:20 to 95:

5.

10. The application of the chiral organic-inorganic hybrid metal halide material with near-infrared circularly polarized luminescence properties as described in claim 1 in the following fields: Near-infrared circularly polarized light-emitting devices; Optical anti-counterfeiting marks and information encryption patterns based on the difference in circularly polarized light emission; or Near-infrared imaging or biological detection.

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