Three-dimensional hybrid halide perovskite deep red luminescent materials and their applications; preparation method based on staged defect-oriented modulation.

Abstract

This invention belongs to the field of novel optoelectronic materials technology, specifically relating to a three-dimensional mixed halide perovskite deep-red luminescent material and its applications, and a preparation method based on staged defect-oriented modulation. It includes three-dimensional metal halide perovskite grains, and first and second type functional molecules distributed on the surface and / or grain boundaries of the perovskite grains; the metal halide perovskite grains have an ABX3 structure. The method involves introducing the first type of functional molecules in the precursor stage and the second type of functional molecules in the film-forming phase inversion stage, allowing the two types of functional molecules to participate in defect modulation at different film-forming stages. This method only modifies the surface / grain boundaries of the perovskite grains through functional molecules, without changing the main crystal lattice structure of the three-dimensional mixed halide perovskite. The prepared perovskite material simultaneously possesses the advantages of low defect state density, high charge transport efficiency, and excellent stability, laying the foundation for the fabrication of high-performance deep-red luminescent diode devices.

Description

Technical Field

[0001] This invention belongs to the field of novel optoelectronic materials technology, specifically relating to a three-dimensional mixed halide perovskite deep red light-emitting material and its application, and a preparation method based on staged defect-oriented control. Background Technology

[0002] Metal halide perovskite materials possess characteristics such as narrow emission lines, high color purity, solution processability, and excellent carrier transport properties, making them promising candidates for applications in displays, lighting, optical communications, and bioimaging. For deep-red light-emitting devices, compared to low-dimensional perovskite materials, three-dimensional (3D) mixed halide perovskite crystal materials, due to their superior charge transport capabilities and tunable bandgap characteristics, have become important candidate materials for constructing high-brightness, high-efficiency deep-red light-emitting devices.

[0003] However, 3D mixed halide perovskite films are prone to forming various defects during solution deposition, including A-site cation-related vacancies, halogen-related vacancies, and uncoordinated metal sites on the surface or at grain boundaries. These defects can induce nonradiative recombination, reduce luminescence efficiency, and may exacerbate ion migration, spectral line drift, and device degradation. Particularly in iodine / bromine mixed systems, coupling between defects and ion migration is common, further affecting the efficiency and stability of deep-red light-emitting devices. Therefore, the photoelectric performance and stability of most 3D mixed halide perovskite materials still lag behind those of 2D and quasi-2D perovskite materials.

[0004] Existing technologies have disclosed various methods for controlling defects in perovskites, such as adding additives to the precursor solution, introducing a surface passivation layer after film formation, using small molecules containing phosphate / phosphonic acid functional groups to coordinate uncoordinated lead sites, and using antisolvents to promote film formation. Related disclosures also indicate that certain organic molecules can passivate vacancy defects, certain phosphonic acid molecules can interact with metal sites, and the antisolvent step itself is a common operation in perovskite film formation processes.

[0005] However, existing technologies typically use additives as a single precursor, or add two additives together to the precursor solution, or perform surface modification uniformly after film formation. They rarely address the issue of different defects forming at different times and spatially distributing during nucleation, growth, phase transition, and surface exposure. This can easily lead to mismatches in the interaction windows of different functional molecules, or mutual interference in the solution stage, making it difficult to simultaneously achieve differentiated regulation of A-site defects, halogen-related defects, and uncoordinated Pb sites.

[0006] Recent studies have attempted a two-additive stepwise introduction strategy (adding ammonium trifluoromethanesulfonate to the precursor and phosphine tri(4-fluorophenyl)oxide to the antisolvent) to improve luminescence performance in quasi-2D green perovskite systems, reporting a peak external quantum efficiency (EQE) of 13.9% for the LEDs (see Du et al., ACS Photonics 2026, 13, 542-548). However, this study only focused on low-dimensional green light systems based on a single halogen, bromine, which naturally possesses high defect tolerance and good environmental stability due to quantum confinement effects. In contrast, 3D mixed-halogen deep-red perovskite systems face more severe challenges: on the one hand, 3D structures lack the quantum confinement protection of low-dimensional materials, resulting in higher defect densities; on the other hand, the iodine / bromine mixture required for deep-red light emission suffers from severe halogen phase separation, with defects and ion migration coupling, leading to increased nonradiative recombination and poor spectral stability. The above studies did not involve 3D mixed halogen deep red light systems, and therefore did not address the efficiency and stability bottlenecks caused by defect-phase separation coupling.

[0007] Therefore, it is necessary to develop a preparation strategy that can introduce different functional molecules at different film formation stages and match the defect formation sequence in order to obtain three-dimensional mixed halide perovskite luminescent materials with both high luminescence efficiency and excellent stability. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention first provides a three-dimensional hybrid halide perovskite deep red light-emitting material.

[0009] The technical solution adopted in this application is as follows: A three-dimensional hybrid halide perovskite deep-red luminescent material, characterized in that it comprises three-dimensional hybrid halide perovskite grains, and first-class and second-class functional molecules distributed on the surface and / or grain boundaries of the perovskite grains; the three-dimensional hybrid halide perovskite grains have an ABX3 structure, wherein A is selected from formamidinium ions (FA). + ), methylammonium ion (MA + ), cesium ions (Cs) + At least one of the following, B is lead ion (Pb). 2+ X is an iodide ion (I - ) and bromide ions (Br - The first type of functional molecule is a combination of R-NH3. + Y - Organic ammonium salt additive molecules, wherein R is any one or a combination of at least two of aromatic, vinyl aromatic, benzyl, substituted benzyl, phenethyl, substituted phenethyl, and alkyl groups, and Y - It is a halide anion, selected from I -or Br - The second type of functional molecule is an additive molecule containing a phosphonic acid functional group, wherein the additive molecule containing a phosphonic acid functional group is selected from any one or a combination of at least two of straight-chain alkylphosphonic acids, branched-chain alkylphosphonic acids, arylphosphonic acids, and substituted arylphosphonic acids.

[0010] The above FA + It is a formamidinium cation with the chemical formula HC(NH2)2. + MA + It is a methylammonium cation with the chemical formula CH3NH3. + .

[0011] Preferably, the formula R-NH3 + Y - The organic ammonium salt additive molecule is selected from at least one of 4-vinylbenzylammonium iodide and 4-vinylbenzylammonium bromide, and the additive molecule containing the phosphonic acid functional group is octylphosphonic acid or its derivative.

[0012] Preferably, the chemical formula of the three-dimensional mixed halide perovskite grains is represented as follows: A 1 a A 2 b Pb(X 1 c X 2 d 3; In the formula, A 1 It is formamidinium ion, A 2 X is an alkali metal cation. 1 X 2 They are independently selected from I and Br, respectively, and a and b are A. 1 and A 2 The molar percentage of the cation at site A is a+b=1; c and d are X. 1 and X 2 The molar percentage of the halogen anion at the X-position is c+d=1; a, b, c, d>0.

[0013] Preferably, the A 1 For FA + A 2 For Cs + X 1 For I - X 2 For Br - Its chemical formula is FA a Cs b Pb(I c Br d3. In the formula, a+b=1, c+d=1, and the value of a is 0.70~0.95, the value of b is 0.05~0.30, the value of c is 0.7~0.98, and the value of d is 0.02~0.30.

[0014] Preferably, the values ​​of a=0.83, b=0.17, c=0.9, and d=0.1 are represented by the chemical formula FA. 0.83 Cs 0.17 Pb(I 0.9 Br 0.1 3.

[0015] The present invention further provides a method for preparing the above-mentioned three-dimensional hybrid halide perovskite deep red luminescent material based on staged defect-oriented control, comprising the following steps: S1. Dissolve the A-site cation source, B-site metal ion source and X-site halide anion source in an organic solvent according to the set molar ratio to obtain a perovskite precursor solution with the chemical composition ABX3. S2. Add a substance having the formula R-NH3 to the perovskite precursor solution. + Y - The organic ammonium salt additive was stirred in the dark until completely dissolved to obtain a precursor solution containing the first type of functional additive. S3. Spin-coat the precursor solution obtained in step S2 onto the substrate to form a liquid film. During the phase when the liquid film transitions from a liquid state to a solid state, add an antisolvent containing an additive with phosphonic acid functional groups to the liquid film. S4. After spin coating, the film is annealed in stages to obtain the desired three-dimensional mixed halide perovskite deep red light emitting material.

[0016] Preferably, the organic solvent is a mixture of DMF and DMSO in a volume ratio of (2:1) to (8:1), and more preferably, the volume ratio is 4:1.

[0017] Preferably, the cation in the A-site cation source is FA. + and Cs + The combination; in the perovskite precursor solution, the ratio of the total molar amount of formamidinium ions and alkali metal cations, the molar amount of metal ions, and the molar amount of halide anions is 1:1:3.

[0018] More preferably, the perovskite precursor solution contains PbI2, PbBr2, FAI and CsI.

[0019] Preferably, the formula R-NH3 + Y - The amount of organic ammonium salt additive added is Pb 2+The amount of substance is 0.1 to 10 mol%, preferably 0.5 to 5 mol%, more preferably 1 mol%.

[0020] Preferably, the criteria for determining the transition of the liquid film from a solution state to a solid phase are changes in color, turbidity, gloss, or abrupt changes in the solvent evaporation state.

[0021] Preferably, the amount of antisolvent used is 3 to 5 μL per square centimeter of substrate area.

[0022] Preferably, the antisolvent is any one or a combination of at least two of toluene, chlorobenzene, and ethyl acetate, with toluene being the most preferred.

[0023] Preferably, the concentration of the additive containing phosphonic acid functional groups is 0.001~1 mg / mL, more preferably 0.01~0.2 mg / mL, and even more preferably 0.05 mg / mL.

[0024] Preferably, the step-by-step annealing procedure is as follows: the first stage is annealing at 30~70℃ for 5~60 s, and the second stage is annealing at 60~100℃ for 1~20 min, wherein the annealing temperature of the second stage is higher than that of the first stage. More preferably, the first stage is annealing at 50℃ for 20 s, and the second stage is annealing at 70℃ for 5 min.

[0025] The present invention also provides the application of the three-dimensional hybrid halide perovskite deep red light-emitting material as described above in the preparation of optoelectronic devices, including but not limited to perovskite light-emitting diodes, laser devices, lighting devices, optical communication devices, and red light display devices.

[0026] For example, a perovskite light-emitting diode includes an anode, a hole transport layer, an emissive layer, an electron transport layer, and a cathode, wherein the emissive layer comprises a three-dimensional mixed halide perovskite deep red light-emitting material as described above.

[0027] The present invention also provides an optoelectronic device comprising the three-dimensional hybrid halide perovskite deep red light-emitting material as described above.

[0028] The beneficial effects of this invention are as follows: This application provides a three-dimensional hybrid halide perovskite deep-red luminescent material based on staged defect-oriented modulation and its preparation method. The method introduces a first type of functional additive in the precursor stage and treats the film formation and phase inversion stage with an antisolvent containing a second type of functional additive. This allows the two types of functional molecules to participate in defect modulation at different film formation stages, thereby achieving differentiated effects on different types of defects, reducing the defect state density of the thin film, suppressing nonradiative recombination, and improving the stability of the material and device. Specifically: (1) Phased introduction to match the defect formation sequence: The first type of functional additive is introduced in the precursor stage, which makes it easier to participate in the regulation of A-site defects and / or halogen-related defects in the early nucleation and crystal growth process; the second type of functional additive is introduced in the film formation and phase inversion stage with the help of antisolvent, which makes it easier to act on uncoordinated Pb sites on the surface or grain boundary exposed in the later stage. The two types of additives are complementary in time window, which helps to reduce mutual interference.

[0029] (2) Differentiated defect control: This application uses different functional groups to play a role in different film formation stages, which can simultaneously control multiple types of defects, reduce non-radiative recombination, and increase the proportion of radiative recombination.

[0030] (3) Maintaining the three-dimensional perovskite main structure: The defect control strategy of this application only modifies the surface / grain boundary of the perovskite grains through functional molecules, without changing the main lattice structure of the three-dimensional mixed halide perovskite. It does not require the system to be transformed into a highly insulating low-dimensional phase, and fully retains the excellent charge carrier transport capability of the three-dimensional mixed halide perovskite itself. This gives the material the dual advantages of low defect state density and high charge transport efficiency, laying the foundation for the fabrication of high-performance optoelectronic devices.

[0031] (4) It is beneficial to improve the quality of thin films and the stability of devices: By controlling the crystallization process in stages and reducing the surface / grain boundary defect state density, it is beneficial to obtain more dense, flat, more efficient and more stable perovskite thin films, which can improve the working efficiency and operating stability of optoelectronic devices based on this material.

[0032] (5) Simple preparation process: This application is based on the conventional solution processing method of perovskite. The preparation method is simple, does not require the introduction of complex equipment or processes, has good process repeatability, and is controllable. It has good prospects for promotion and application.

[0033] (6) The phased defect control approach proposed in this application has good applicability to the three-dimensional mixed halide perovskite deep red luminescence system. Attached Figure Description

[0034] Figure 1 The image shows SEM images of the perovskite films prepared in Experiment 1. In the image, (a) is the Control group of perovskite films without additive modification, and (b) is the VBAI+OPA group of perovskite films containing two additive molecules.

[0035] Figure 2Steady-state photoluminescence (PL) spectra of different perovskite films (Control group, VBAI group, OPA group, and VBAI+OPA group) prepared in Experiment 1 are shown. The Control group represents perovskite films without additive modification; the VBAI group represents perovskite films modified with VBAI as an additive; the OPA group represents perovskite films modified with OPA as an additive; and the VBAI+OPA group represents perovskite films co-modified with both VBAI and OPA additives.

[0036] Figure 3 X-ray diffraction (XRD) patterns of different perovskite films (Control group, VBAI group and VBAI+OPA group) prepared for Experiment 1.

[0037] Figure 4 Time-resolved photoluminescence (TRPL) decay curves (corresponding nonlinear fitting curves) of different perovskite films (Control group, VBAI group and VBAI+OPA group) prepared in Experiment 1.

[0038] Figure 5 The figures show a comparison of the photoluminescent quantum yield (PLQY) and two recombination rates of charge carriers for different perovskite thin films (Control group, VBAI group, and VBAI+OPA group) prepared in Experiment 1. Figure (a) shows the photoluminescent quantum yield (PLQY) test results, and figure (b) shows the radiative recombination rate (kJ / L) of charge carriers. rad ) and nonradiative recombination rate (k nonrad A comparison chart.

[0039] Figure 6 Temperature-dependent steady-state fluorescence (PL) spectra of the perovskite films (Control group and VBAI+OPA group) prepared for Experiment 1.

[0040] Figure 7 This is a SEM image of the cross-section of the perovskite light-emitting diode device prepared in Example 1.

[0041] Figure 8 To find the optimal VBAI concentration in Experiment 2, the experimental test results are shown in the figure. (a) shows the JVL curves of devices with different VBAI concentrations, and (b) shows the EQE-J curves of devices with different VBAI concentrations.

[0042] Figure 9 In Experiment 2, the experimental test results were obtained to find the optimal OPA concentration under the optimal VBAI concentration. In the figure, (a) is the JVL curve of the device with different OPA concentrations, and (b) is the EQE-J curve of the device with different OPA concentrations.

[0043] Figure 10The JV curves are for single-electron devices prepared using different perovskite thin films in Experiment 3.

[0044] Figure 11 The figures show the results of first-principles calculations on the pure additive material and the perovskite film modified with additives in Experiment 4. In the figure, (a) is the charge density difference diagram of VBAI on the FA / Cs-I termination surface obtained by DFT calculation, and (b) is the side view of the charge density difference diagram of OPA on the Pb-I termination surface obtained by DFT calculation.

[0045] Figure 12 The figures show the Fourier transform infrared (FT-IR) spectra of the pure VBAI material and the perovskite film modified with the additive in Experiment 4. Figure (a) shows the FT-IR spectrum of the pure VBAI material and the FT-IR spectrum of the VBAI-modified perovskite film, and (b) shows the FT-IR spectra of the pure OPA material and the OPA-modified perovskite film.

[0046] Figure 13 The X-ray photoelectron spectroscopy (XPS) spectra of the perovskite films in the Control group and the VBAI+OPA group in Experiment 4 are shown in Figure (a) and the peaks of Pb (b)), I (c) and Br (d) are shown in Figure (b)).

[0047] Figure 14 The angular emission distribution of the deep red perovskite light-emitting devices in the Control group and VBAI+OPA group in Experiment 5 is shown.

[0048] Figure 15 The image shows the CIE color coordinates of the deep red perovskite light-emitting device in the VBAI+OPA group in Experiment 5.

[0049] Figure 16 The EQE statistical distribution diagrams for the devices in the Control group and VBAI+OPA group in Experiment 5 are shown.

[0050] Figure 17 The EL spectra of the Control group and VBAI+OPA group devices in Experiment 5 under different driving voltages are shown.

[0051] Figure 18 The electroluminescence (EL) spectra of the deep red perovskite light-emitting devices in the Control group and VBAI+OPA group in Experiment 5 at different temperatures.

[0052] Figure 19 For the T of the Control group and VBAI+OPA group devices in Experiment 5 50 Working life curve.

[0053] Figure 20 The EQE decay curves are for the unencapsulated Control group and VBAI+OPA group deep red perovskite light-emitting devices in Experiment 5, after long-term storage in a nitrogen environment. Detailed Implementation

[0054] Unless otherwise stated, the terms used herein have the meanings commonly understood by those skilled in the art. Unless otherwise specified, all experimental materials and reagents used in the experiments are commercially available. For experiments where specific techniques or conditions are not specified, the procedures described in the literature in this field or the product instructions should be followed.

[0055] The technical solution of the present invention will be described in more detail below with reference to experiments.

[0056] Experiment 1

[0057] 1. Preparation of perovskite thin films

[0058] This embodiment illustrates the method of preparing three-dimensional deep red perovskite luminescent material thin films by introducing two types of functional additives in stages, as described in this invention.

[0059] 1) Preparation of precursor solution

[0060] According to satisfying FA 0.83 Cs 0.17 Pb(I 0.9 Br 0.1 PbI2, PbBr2, FAI and CsI were weighed in stoichiometric ratio and dissolved in anhydrous DMF / DMSO (volume ratio 4:1) to prepare a perovskite precursor solution.

[0061] 2) Introduction of Class I functional additives

[0062] The first type of functional additive, 4-vinylbenzylammonium iodide (VBAI), was added to the above perovskite precursor solution in an amount relative to Pb. 2+ Approximately 1 mol% of the solution was added and stirred until the solution became clear and homogeneous, thus obtaining a perovskite precursor solution containing VBAI.

[0063] 3) Film formation and introduction of second-class functional additives

[0064] The pretreated substrate was placed on a spin coater, and the perovskite precursor solution obtained in step 2 was spin-coated onto the substrate surface at 5000 rpm to form a liquid film. During the window period of 10 to 20 seconds after the start of spin coating, that is, when the liquid film begins to change color from transparent to cloudy or shows obvious gloss changes due to solvent evaporation, about 5 μL of chlorobenzene antisolvent containing the second type of functional additive octylphosphonic acid (OPA) was added dropwise to the liquid film, wherein the concentration of OPA in chlorobenzene was about 0.05 mg / mL.

[0065] 4) Annealing treatment

[0066] After spin coating, the resulting film is subjected to stepwise annealing: first annealing at about 50°C for about 20 s, followed by annealing at about 70°C for about 5 min, to obtain the desired perovskite material film.

[0067] 2. Test Characterization

[0068] The perovskite film prepared without the addition of the first-class functional additive VBAI and without the introduction of the second-class functional additive OPA, with all other preparation methods being the same, was designated as the Control group. The perovskite film prepared with only the addition of the first-class functional additive VBAI and without the introduction of the second-class functional additive OPA, with all other preparation methods being the same, was designated as the VBAI group. The perovskite film prepared without the addition of the first-class functional additive VBAI and only with the introduction of the second-class functional additive OPA, with all other preparation methods being the same, was designated as the OPA group. Perovskite films containing both additive molecules, VBAI and OPA, were designated as VBAI+OPA, and the following tests were performed: (1) Characterization of film morphology The surface morphology of the films in the Control group and the VBAI+OPA group was observed using scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown.

[0069] Depend on Figure 1 It is evident that the Control group film surface exhibits more pronounced uneven areas, while the VBAI+OPA group film is generally denser and smoother, indicating that the phased introduction of the dual additives is beneficial for improving film morphology and reducing surface defects.

[0070] (2) Steady-state photoluminescence characterization

[0071] Steady-state photoluminescence (PL) testing was performed on different sample films: using an Edinburgh Instruments FLS980 spectrometer equipped with an integrating sphere (SC-30), the film samples were excited with light at a wavelength of 450 nm, and their photoluminescence quantum yield (PLQY) and steady-state PL spectra were measured simultaneously.

[0072] The results are as follows Figure 2 As shown, compared with the Control group, the luminescence intensity of the OPA group was enhanced, and the luminescence intensity of the VBAI group and the VBAI+OPA group was significantly enhanced. Among them, the VBAI+OPA group showed a stronger luminescence response, indicating that the strategy of introducing two additives in stages in this invention is beneficial to reducing non-radiative recombination loss and improving the photoluminescence efficiency of the thin film.

[0073] (3) Crystal structure characterization

[0074] X-ray diffraction (XRD) was used to test the films in the Control group, VBAI group, and VBAI+OPA group. The results are as follows: Figure 3 As shown.

[0075] Depend on Figure 3 As can be seen, all samples maintained typical three-dimensional perovskite diffraction characteristic peaks, with no obvious impurity phase peaks observed, indicating that the introduction of the two types of additives did not destroy the main perovskite crystal structure. Compared with the Control group, the main diffraction peak intensities of the VBAI group and the VBAI+OPA group were enhanced, indicating that the addition of the first type of functional additive improved the film crystallinity.

[0076] (4) Time-resolved fluorescence and quantum efficiency characterization

[0077] Time-resolved photoluminescence (TRPL) measurement: The time-correlated single-photon counting (TCSPC) module of the same spectrometer was used, with an excitation wavelength of 369 nm and an excitation intensity of 0.6 mW cm⁻¹. -2 Under the given conditions, the time-resolved photoluminescence decay curve of the thin film was recorded.

[0078] TRPL was used to test the carrier decay behavior of different sample films, and the results are as follows: Figure 4 As shown, the decay lifetime of the VBAI+OPA group is significantly longer than that of the Control group and the VBAI single additive group, indicating that the synergistic effect of the two additives can effectively prolong the carrier lifetime.

[0079] Furthermore, the radiative recombination rate (kΩ) was calculated by using PLQY values ​​and TRPL spectra of different thin film samples through double exponential fitting to obtain fluorescence lifetime values. rad ) and nonradiative recombination rate (k nonrad ).

[0080] like Figure 5 As shown, Figure 5 Figure 'a' shows a bar chart of the PLQY test results for three perovskite thin films. Figure 5 In the figure, b represents the radiative recombination rate (kb) of the three perovskite thin films. rad ) and nonradiative recombination rate (k nonrad ).Depend on Figure 5As can be seen, the VBAI+OPA group has higher PLQY and lower nonradiative recombination rate, further demonstrating that the strategy described in this invention can effectively reduce defect-related losses.

[0081] (5) Temperature-dependent optical stability characterization

[0082] Temperature-dependent PL test: The sample was placed in an Oxford Instruments Optistat DNV cryostat and PL spectra were collected at 20 K intervals within a temperature range of 80 K to 380 K. The sample was stabilized for 15 minutes before each temperature point test and then the data was collected.

[0083] The results are as follows Figure 6 As shown, compared to the Control group, the PL peak of the VBAI+OPA group films exhibits a slight blue shift and a significantly narrower emission peak. Combined with the defect state characterization results, this blue shift indicates that the passivation effect of surface and grain boundary defects suppresses tail states and promotes radiative recombination processes closer to the intrinsic band edges. The narrower PL emission peak of the VBAI+OPA group films indicates reduced structural disorder, weakened electron-phonon coupling, and fewer localized states, suggesting improved crystal quality and optical uniformity of the films.

[0084] The above experiments show that the strategy of introducing two types of functional additives in stages as provided in this application can improve the morphology of the film, enhance the crystal quality, and significantly improve its optical performance while maintaining the three-dimensional perovskite matrix structure.

[0085] Experiment 2

[0086] 1. Fabrication of deep red perovskite light-emitting diode devices using perovskite thin films.

[0087] First, the ITO substrate was cleaned: it was ultrasonically cleaned sequentially in deionized water, acetone, and ethanol for 30 minutes each, followed by O2 plasma treatment for 10 minutes. Then, under a nitrogen atmosphere, the filtered poly-TPD chlorobenzene solution (6 mg / mL) was... - ¹) Spin-coating at 2000 rpm for 40 seconds, followed by annealing at 120 °C for 20 minutes, and then O2 plasma treatment for 10 seconds. Next, spin-coating a PFN-Br methanol solution (0.2 mg / mL) onto the poly-TPD layer. -1 The rotation speed was 5000 rpm, the time was 20 seconds, and after completion, it was left to stand for later use. The perovskite luminescent layer was prepared using the aforementioned method: FA 0.83 Cs 0.17 Pb(I 0.9 Br 0.1The precursor (0.169 M, DMF / DMSO 4:1 solvent with added VBAI) was spin-coated at 5000 rpm for 10-20 seconds at room temperature. During spin-coating, when the film began to change color, toluene antisolvent containing different concentrations of OPA was added dropwise, followed by two-step annealing: annealing at 50 °C for 20 seconds, and then annealing at 70 °C for 5 minutes. Afterwards, TPBi (approximately 20 nm thick), LiF (approximately 1 nm thick), and Al (approximately 80-100 nm thick) were deposited sequentially by thermal evaporation to complete the device fabrication. Throughout the entire fabrication process, except for the evaporation process which was completed in a vacuum chamber and the ITO substrate cleaning which was completed in air, the fabrication of other thin films was carried out under a nitrogen atmosphere.

[0088] Cross-sectional SEM image of the fabricated perovskite light-emitting diode device is shown below. Figure 7 As shown in the figure, ITO (indium tin oxide) is the transparent anode, Poly-TPD / PFN-Br is the hole transport layer, Perovskite is the light-emitting layer, TPBi is the electron transport layer, and LiF / Al (lithium fluoride / aluminum) is the composite cathode.

[0089] 2. Optimization experiment for the optimal concentration of VBAI used in the preparation of perovskite light-emitting diodes.

[0090] Based on the above preparation method, FA 0.83 Cs 0.17 Pb(I 0.9 Br 0.1 The concentrations of VBAI added to the precursor were set to 0 mol%, 0.5 mol%, 1 mol%, 2 mol%, and 5 mol, respectively.

[0091] The final device results are: ITO (30nm) / Poly-TPD (20nm) / PFN-Br (3nm) perovskite light-emitting layer (80-100nm) / TPBi (20nm) / LiF (1nm) / Al (80-100nm), where the numbers in parentheses represent the thickness of the corresponding thin film.

[0092] Device Testing: The electroluminescence performance of the devices was characterized using a fully calibrated integrated light-emitting diode (LED) device testing system under an inert nitrogen atmosphere. The current density-voltage-luminance (JVL) characteristics of the devices were recorded using a synchronized precision source meter (Keithley 2400) and a calibrated silicon photodiode (FDS-100-CAL, Thorlabs). Electroluminescence (EL) spectra were acquired using a fiber-coupled spectroradiometer (UVN-SR, StellarNet Inc.), and the corresponding external quantum efficiency (EQE) was calculated to obtain the EQE-J curve.

[0093] The performance comparison results of devices fabricated under the above different VBAI concentration conditions are as follows: Figure 8 As shown. Figure 8 Figure a shows the current density-voltage-luminance curves (JVL curves) for devices with different VBAI concentrations, and Figure b shows the corresponding external quantum efficiency-current density curves (EQE-J curves). The results show that as the VBAI concentration increases, the device turn-on voltage decreases, and the luminance and external quantum efficiency exhibit a trend of first increasing and then decreasing, with the device performance being optimal at approximately 1 mol%. This indicates that the introduction of an appropriate amount of VBAI is beneficial for improving the film formation quality and suppressing defects, while excessive introduction may affect charge transport due to the enrichment of organic components. The figures also show that the turn-on voltage of the unmodified device is 2.7 V, while after introducing VBAI, the turn-on voltage decreases to 2.4 V, and the luminance of the device significantly increases, with the highest luminance of the unmodified diode device reaching 457 cd / m². -2 Devices modified with a single VBAI additive achieved a peak brightness exceeding 7500 cd / m². -2 .

[0094] 3. Optimization experiment for the optimal concentration of OPA used in the preparation of perovskite light-emitting diodes

[0095] Based on the above preparation method, the amount of the first type of functional additive VBAI was fixed at 1 mol%, and the concentration of OPA in the antisolvent toluene was set to 0 mg / mL, 0.01 mg / mL, 0.05 mg / mL, 0.1 mg / mL and 0.2 mg / mL, respectively, to prepare perovskite composite films.

[0096] Device Testing: The electroluminescence performance of the device was characterized using a fully calibrated integrated test system under an inert nitrogen atmosphere. The current density-voltage-luminance (JVL) characteristics of the device were recorded using a synchronized precision source meter (Keithley 2400) and a calibrated silicon photodiode (FDS-100-CAL, Thorlabs). Electroluminescence (EL) spectra were acquired using a fiber-coupled spectroradiometer (UVN-SR, StellarNet Inc.), and the corresponding external quantum efficiency (EQE) was calculated to obtain the EQE-J curve.

[0097] The performance results of the devices prepared under the above different OPA concentration conditions are as follows: Figure 9 As shown. Figure 9 In the figure, 'a' represents the JVL curves of devices with different OPA concentrations. Figure 9Figure b shows the corresponding EQE-J curve. The results indicate that, under the condition of a fixed optimal VBAI concentration, the device performance further improves with increasing OPA concentration, exhibiting a clear concentration window. When the OPA concentration is approximately 0.05 mg / mL, the device exhibits superior brightness and external quantum efficiency, while further increasing the OPA concentration leads to a performance decrease. This result suggests that the amount of the second type of functional additive introduced also needs to be controlled within an appropriate range to achieve a better regulatory effect. The figure also shows that after introducing the dual additives, the device's turn-on voltage decreases to 1.7V, and the device brightness significantly increases. The highest brightness of the device modified with the dual additives exceeds 10000 cd / m². -2 .

[0098] Experiment 3

[0099] Experiments on the fabrication of perovskite single-electron devices

[0100] Fabrication of single-electron devices: A diluted SnO2 dispersion (diluted with deionized water at a volume ratio of 1:6) was spin-coated onto a cleaned ITO substrate at 4000 rpm for 30 seconds, followed by annealing at 150°C for 30 minutes and O2 plasma treatment for 5 minutes. For the fabrication of perovskite thin films, FA... 0.83 Cs 0.17 Pb(I 0.9 Br 0.1 3. The precursor (0.169 M, DMF / DMSO 4:1 solvent, VBAI added at 0 or 1 mol%) was spin-coated at 5000 rpm for 60 seconds at room temperature. During spin-coating, when the film began to change color, chlorobenzene antisolvent containing different concentrations of OPA was added dropwise (the concentration of OPA in the chlorobenzene antisolvent was 0 or 0.05 mg / mL). Then, a two-step annealing was performed (annealing at 50℃ for 20 seconds, and then annealing at 70℃ for 5 minutes).

[0101] According to the above method, three types of perovskite films were prepared: a perovskite film without additives, denoted as Control; a perovskite film containing VBAI additive, denoted as VBAI; and a perovskite film containing both VBAI and OPA additives, denoted as VBAI+OPA.

[0102] Furthermore, a chlorobenzene solution (20 mg / mL) of PCBM was spin-coated inside the glove box. -1 The spin coating conditions were 3000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes. Finally, an 80 nm thick Ag electrode was deposited by thermal evaporation to complete the fabrication of the single-electron device.

[0103] Device Testing: The electroluminescence performance of the device was characterized using a fully calibrated integrated test system under an inert nitrogen atmosphere. The current density-voltage-luminance (JV) characteristics of the device were recorded using a synchronized precision source meter (Keithley 2400) and a calibrated silicon photodiode (FDS-100-CAL, Thorlabs).

[0104] The results are as follows Figure 10 As shown. In space charge confined current (SCLC) analysis, the trap fill limit voltage (V) is identified from the dark-state JV curve of a single-carrier device. TFL This refers to the inflection point where the curve transitions from a high-slope region to the Child region (where the slope becomes significantly gentler). The trap state density N is then calculated using the formula. traps :

[0105] In the formula, q is the charge of the electron, ε0 and ε r These are the vacuum permittivity and relative permittivity, respectively, and L is the thickness of the perovskite film.

[0106] Depend on Figure 10 It is evident that the trap fill threshold voltage of the VBAI+OPA group devices is lower than that of the Control group and the VBAI single-additive group. This is based on the calculated defect state density N. traps It can be seen that by introducing two types of functional additives in stages using the present invention, the defect state density of the perovskite film is significantly reduced.

[0107] It can be seen that the phased introduction strategy provided in this application can effectively suppress the formation of trapped states and reduce the trapped state density of perovskite thin films, thereby providing a foundation for the improvement of device efficiency and stability.

[0108] Experiment 4

[0109] Theoretical calculations and spectroscopic mechanism analysis

[0110] 1. First Principles Calculation and Analysis

[0111] Methods and Contents: The VASP software package was used to process the exchange correlation energy based on the Projected Added Wave (PAW) method and the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation, and Grimme's DFT-D3 correction was added to describe the van der Waals interaction. Spin-orbit coupling was not considered. The kinetic cutoff energy of the plane wave basis set was set to 400 eV, and only the Γ point was used for Brillouin zone sampling. To simulate the mixed cation perovskite system, a 4×4×1 surface supercell model containing 4 atomic layers was constructed along the (001) direction, with a 18 Å vacuum layer set along the surface normal direction. During structural relaxation, the bottom two atomic layers were fixed to simulate the bulk effect, and the top two atomic layers were completely relaxed; the atomic force convergence criterion was 0.05 eV / Å, and the total energy change converged to 10 eV / Å. -5 eV. Two types of surfaces were considered: FA-I termination and Pb-I termination, with neutral FA holes used as representative intrinsic defects. Adsorbed molecules were placed at appropriate sites on the surface for complete relaxation. The charge redistribution induced by additive adsorption was investigated using differential charge density.

[0112] Using first-principles calculations, the interactions between VBAI and the FA / Cs-I termination surface, and between OPA and the Pb-I termination surface, were systematically analyzed. The results are as follows: Figure 11 As shown in the figure, a is a partial differential charge density map of VBAI on the FA / Cs-I termination surface, and b is a partial differential charge density map of OPA on the Pb-I termination surface. Figure a shows that after the introduction of VBAI, a significant charge redistribution phenomenon occurs near its surface-related sites, indicating that the first type of functional additive can interact strongly with the A-site-related defect region. Figure b shows that after OPA interacts with the Pb-I termination surface, a significant charge redistribution occurs near the Pb-related sites on the surface, indicating that the second type of functional additive can form a strong interaction with uncoordinated Pb sites.

[0113] 2. FT-IR and XPS Analysis

[0114] Fourier transform infrared (FT-IR) spectroscopy was performed on pure additive materials (VBAI or OPA) and perovskite films modified with additives (VBAI+OPA). The results are as follows: Figure 12 As shown. By Figure 12 It is evident that the relevant characteristic peaks changed after the addition of the additive, indicating that there is a significant interaction between the additive and the perovskite surface.

[0115] Furthermore, based on the thin films prepared in Example 1, X-ray photoelectron spectroscopy (XPS) tests were performed on the Control group and the VBAI+OPA group thin films, and the results are as follows. Figure 13 As shown. By Figure 13As can be seen in Figure a, the XPS spectrum of the perovskite film shows new elemental peaks after the introduction of the two additives. Figure 13 As can be seen from the middle bd, the peak positions of related elements shifted after the introduction of the two additives, further indicating that the first and second type of functional additives changed the local chemical environment of different defect sites on the perovskite surface.

[0116] The experimental results above show that the two types of functional additives used in this application do not simply have a superimposed effect in perovskite films, but rather exhibit differentiated regulatory effects on different types of defects, thereby achieving more effective defect passivation.

[0117] Experiment 5

[0118] Tests on the luminous performance and stability of PeLED devices

[0119] Light-emitting diode devices were fabricated using different perovskite thin films, and the fabrication method is described in Experiment 2. The resulting device structure is as follows: ITO (30nm) / Poly-TPD (20nm) / PFN-Br (3nm) / perovskite light-emitting layer (80-100nm) / TPBi (20nm) / LiF (1nm) / Al (80-100nm).

[0120] The devices are classified into two groups based on the amount of additives used in the thin film: Control group (corresponding to perovskite thin films without additives) and VBAI+OPA group (perovskite thin films containing both VBAI and OPA additives).

[0121] 1. Testing the luminous performance of PeLED devices

[0122] The luminescence intensity of PeLEDs at different emission angles in the Control group and VBAI+OPA group was collected using an angle-measuring luminescence system, and the CIE color coordinates were measured and calculated using an electroluminescence spectrometer.

[0123] Figure 14 The angular emission distribution curves for the Control group device and the VBAI+OPA device show that both strictly follow the Lambertian distribution, indicating that the additives did not change the angular distribution characteristics of the emitted light. Notably, the VBAI+OPA device exhibits slightly higher emission intensity at most angles, which is consistent with the improved radiative recombination efficiency.

[0124] Figure 15 The CIE color coordinate diagram of the VBAI+OPA group device shows that the emission color of the device modified with VBAI and OPA is deep red.

[0125] 2. Stability test of dual-additive process

[0126] The statistical distribution of EQE for devices in the Control group, VBAI group, and VBAI+OPA group was analyzed, and the results are as follows: Figure 16 As shown. By Figure 16 It is evident that the VBAI+OPA group of devices not only has higher peak efficiency but also exhibits more concentrated batch-to-batch distribution, indicating that the method provided in this application has good repeatability.

[0127] 3. Characterization of device spectral stability

[0128] 1) Stability testing of the device's EL spectrum under different applied voltages. Electroluminescence (EL) spectra were acquired using a fiber-coupled spectroradiometer (UVN-SR, StellarNet Inc.) at room temperature in an inert nitrogen atmosphere. These spectra were used to analyze the stability of the EL spectra under different applied voltages (3V, 4V, 5V, 6V, 7V).

[0129] like Figure 17 As the voltage increases, the emission peak of the Control group devices exhibits a slight redshift, while the spectral background gradually deteriorates. In contrast, the VBAI+OPA group devices maintain a stable emission peak position and a cleaner spectral background throughout the entire voltage range. The Control group devices show a slight redshift and spectral background degradation with increasing voltage, while the VBAI+OPA devices consistently maintain a stable emission peak and a clear spectral profile, indicating that they have a more stable band-edge recombination process under high bias operating conditions.

[0130] 2) Stability test of device EL spectrum under different ambient temperatures. The device was placed in an Oxford Instruments Optistat DNV cryostat, and a voltage of 2.7 V was applied. The device temperature was tested starting from 0°C, and the temperature was increased by 10°C each time and stabilized for 10 minutes before testing, until it reached 80°C, and variable temperature EL test was carried out.

[0131] like Figure 18 The normalized electroluminescence (EL) spectra of the Control group device and the VBAI+OPA device at different temperatures (0-80℃) are shown. Although both devices maintain stable peak positions, the Control group device exhibits significant spectral broadening and fluctuations under high temperature conditions, while the VBAI+OPA device maintains a smooth and symmetrical emission spectrum, indicating that its thermal activation defects are suppressed.

[0132] The electroluminescence (EL) spectra of the device were tested at different temperatures and driving voltages, and the results showed that the phased introduction strategy described in this invention is beneficial to improving the spectral stability of the device.

[0133] 4. Device lifespan testing

[0134] 1) Device T50 Testing. The electroluminescence performance of the device was characterized using a fully calibrated integrated test system under an inert nitrogen atmosphere. Current density-voltage-luminance (JVL) characteristics of the device were recorded using a synchronized precision source meter (Keithley 2400) and a calibrated silicon photodiode (FDS-100-CAL, Thorlabs). Electroluminescence (EL) spectra were acquired using a fiber-coupled spectroradiometer (UVN-SR, StellarNet Inc.), and the corresponding external quantum efficiency (EQE) was calculated. All tests were performed at room temperature. The test was conducted at 5 mA cm⁻¹ under nitrogen atmosphere. -2 A constant current drive was used to monitor the time required for the brightness to drop to 50% of its initial value in an unpackaged device, and to evaluate T. 50 life.

[0135] The results are as follows Figure 19 As shown, the T of the device after introducing the two additives can be seen. 50 Lifespan increases more than 10 times.

[0136] 2) Long-term stability of device lifetime. Unpackaged devices in the Control and VBAI+OPA groups were stored in a nitrogen atmosphere. EQE was tested periodically over 120 days, and the EQE decay curve was observed. The long-term lifetime of the devices was assessed based on the change in EQE over time. The EQE testing method was the same as the previously described EQE testing method. For ease of comparison, the EQE values ​​were normalized.

[0137] See results Figure 20 As can be seen, the VBAI+OPA group device prepared using the technical solution of this invention still retains 98% of the initial EQE after 120 days. In contrast, the Control group device retains 77% of the initial EQE. The VBAI+OPA group device exhibits a more stable operating life, indicating that by introducing two types of functional additives in stages to regulate the thin film crystallization process and crystal defects, not only can the device efficiency be improved, but the device's operational stability can also be significantly enhanced.

[0138] The experimental results above demonstrate that the perovskite light-emitting diodes prepared using the phased introduction strategy provided in this application outperform the Control group and the single additive group in terms of turn-on voltage, brightness, external quantum efficiency, emission spectrum stability, and operating lifetime. This indicates that the scheme in this application can effectively improve the overall performance of deep red perovskite light-emitting devices.

[0139] Referring to the background section of this paper, previous studies have reported a strategy of stepwise addition of functional molecules to precursor and antisolvent components, applied to a quasi-two-dimensional green perovskite system (Du et al., ACS Photonics 2026, 13, 542-548), achieving a peak EQE of 13.9%. However, the mechanism of action and the applicable system (quasi-two-dimensional) of this study differ significantly from those in this application. In particular, this study did not address, and could not resolve, two major technical challenges unique to three-dimensional mixed halogen deep red light systems: (i) efficiency degradation caused by phase separation of iodine / bromine mixed halogens; and (ii) intensified nonradiative recombination due to the low defect tolerance of the three-dimensional structure.

[0140] This application achieves significant performance breakthroughs in the field of deep-red perovskite luminescent materials and devices by introducing VBAI (precursor liquid) and OPA (antisolvent) in stages into a three-dimensional deep-red mixed halogen system. The peak EQE of the deep-red luminescent device reaches 23.16%, the turn-on voltage is as low as 1.7V, and the operating lifetime (T50) is increased by more than 10 times. Furthermore, the unencapsulated device retains 98% of its initial EQE after 120 days of storage in a nitrogen environment. This demonstrates that the modulation strategy provided in this application plays a crucial role in improving perovskite crystal luminescent materials and has promising application prospects.

[0141] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-dimensional mixed halide perovskite deep red light emitting material characterized in that, comprise three-dimensional mixed halide perovskite grains, and a first type of functional molecule and a second type of functional molecule distributed on the surface and / or grain boundaries of the perovskite grains; the three-dimensional mixed halide perovskite grains are of ABX3structure, wherein A is selected from at least one of FA + , MA + , Cs + , B is Pb 2+ , and X is a combination of I - and Br - ; the first type of functional molecule is an organic ammonium salt additive molecule having a formula of R-NH3 + Y - , wherein R is any one or a combination of at least two of an aromatic group, a vinyl aromatic group, a benzyl group, a substituted benzyl group, a phenethyl group, a substituted phenethyl group, an alkyl group, and Y - is a halide anion selected from I - or Br - ; the second type of functional molecule is a phosphonic acid functional group containing additive molecule selected from any one or a combination of at least two of a straight chain alkyl phosphonic acid, a branched chain alkyl phosphonic acid, an aryl phosphonic acid, a substituted aryl phosphonic acid.

2. The three-dimensional mixed halide perovskite deep red light emitting material of claim 1, wherein, The chemical formula of the three-dimensional mixed halogen perovskite crystal grain is: FA a Cs b Pb(I c Br d )3, wherein a+b=1, c+d=1, and the value of a is 0.70-0.95, the value of b is 0.05-0.30, the value of c is 0.7-0.98, and the value of d is 0.02-0.

30.

3. The three-dimensional mixed halide perovskite deep red light emitting material of claim 2, wherein, The a = 0.83, b = 0.17, c = 0.9, d = 0.1, chemical formula is expressed as FA 0.83 Cs 0.17 Pb(I 0.9 Br 0.1 )3.

4. The three-dimensional mixed halide perovskite deep red light emitting material of claim 1, wherein, The formula R-NH3 + Y - The organic ammonium salt additive molecule is selected from at least one of 4-vinylbenzylammonium iodide and 4-vinylbenzylammonium bromide, and the additive molecule containing the phosphonic acid functional group is octylphosphonic acid or its derivative.

5. A method for preparing the three-dimensional mixed halide perovskite deep red light-emitting material according to any one of claims 1-4 based on stage-defect-oriented regulation, characterized in that, The method comprises the following steps: S1. Dissolving a source of A-site cations, a source of B-site metal ions and a source of X-site halide anions in an organic solvent according to a set molar ratio to obtain a perovskite precursor solution with a chemical composition of ABX3; S2. To the perovskite precursor solution, an organic ammonium salt additive having the formula R-NH3 + Y - is added, stirred in the dark until complete dissolution, resulting in a precursor solution containing a first type of functional additive; S3. Rotating and coating the precursor solution obtained in step S2 on a substrate to form a liquid film, and adding an anti-solvent containing a phosphonic acid functional group additive to the liquid film during the phase transition of the liquid film from a liquid to a solid phase; S4. After the rotation and coating is completed, the thin film is subjected to step-by-step annealing to obtain a required three-dimensional mixed halide perovskite deep red light emitting material.

6. The production method according to claim 5, wherein The organic solvent is a mixed solvent of DMF and DMSO, and the volume ratio of the two is (2:1)~(8:1); the cation in the A-site cation source is FA + and a combination of Cs + ; in the perovskite precursor solution, the total molar amount of formamidinium ion and alkali metal cation, the molar amount of metal ion, and the molar amount of halide anion are in a ratio of 1:1:

3.

7. The production method according to claim 5, characterized by, said having the formula R-NH3 + Y - amount of 0.1 to 10 mol% of the amount of substance of the Pb 2+ amount of 3 to 5 μL per square centimeter of substrate area, the solvent being any one of toluene, chlorobenzene, ethyl acetate or a combination of at least two thereof, the concentration of the additive containing phosphonic acid functionality being 0.001 to 1 mg / mL.

8. The method of claim 5, wherein the step of preparing is characterized by, The procedure of the step-by-step annealing is that the first stage is annealing at a temperature of 30-70°C for 5-60 s, and the second stage is annealing at a temperature of 60-100°C for 1-20 min, and the annealing temperature of the second stage is higher than that of the first stage.

9. Use of the three-dimensional mixed halide perovskite deep red light emitting material according to any one of claims 1-4 in the preparation of optoelectronic devices, including but not limited to perovskite light emitting diodes, laser devices, lighting devices, optical communication devices, red light display devices.

10. An optoelectronic device, characterized in that An optoelectronic device comprising the three-dimensional mixed halide perovskite deep red light emitting material according to any one of claims 1-4.

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