Preparation method of perovskite quantum dot conductive film with epitaxial heterojunction and its products and applications

Abstract

The present application discloses a preparation method of a perovskite quantum dot conductive film with an epitaxial heterojunction, its products and applications, and belongs to the field of semiconductor heterojunction technology. The preparation method of the present application comprises: providing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand respectively, and mixing the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand to form a perovskite heterojunction precursor solution, and then pouring the perovskite heterojunction precursor solution on a substrate, and sequentially performing film forming and annealing treatment to obtain a perovskite quantum dot conductive film with an epitaxial heterojunction. The present application efficiently constructs an epitaxial heterostructure in one step through the interaction between the first ligand and the second ligand, which not only simplifies the preparation steps and removes the limitation of the lattice matching of the substrate material, making it suitable for industrial production, but also gives the perovskite quantum dot conductive film with an epitaxial heterojunction stability in the natural environment.

Description

Technical Field

[0001] The present application belongs to the technical field of semiconductor heterojunction materials, and in particular relates to a method for preparing a perovskite quantum dot conductive film with an epitaxial heterojunction, and its products and applications. Background Art

[0002] Metal halide perovskites are widely used in optoelectronic applications such as solar cells, LEDs, and detectors due to their advantages, including tunable band gaps, high color purity, simple preparation, and low cost. However, the intrinsic phase of iodine-based perovskite materials (CsPbI3, FAPbI3) is unstable at room temperature, significantly hindering the achievement of high-quality optical properties in iodine-based perovskite quantum dot conductive films and their application in high-efficiency optoelectronic devices. Therefore, it is necessary to develop strategies for preparing iodine-based perovskite quantum dot conductive films with stable intrinsic phases and good conductivity.

[0003] Semiconductor epitaxial heterostructures are semiconductor structures that are integrated and produced from two or more different semiconductor materials. Currently, the common preparation method for metal halide perovskite heterojunctions is a two-step growth method. For example, Xu Sheng et al. prepared a perovskite single crystal substrate and then used a solvent evaporation method to prepare another perovskite material on the substrate to obtain a heteroepitaxial perovskite single crystal composite material; Huang Wei et al. dissolved lead halide and organic ligands in a polar organic solvent and vigorously oscillated to obtain a precursor solution of the perovskite substrate. They then prepared another perovskite nanocrystal by hot injection and dispersed it in a non-polar organic solvent. They then used an anti-solvent method to prepare a shaped perovskite heterojunction material, that is, while vigorously stirring the perovskite substrate precursor solution, a toluene solution of perovskite nanocrystals was added.

[0004] However, the two-step growth method for preparing semiconductor epitaxial heterostructures has the following defects and shortcomings: First, the preparation of perovskite single crystals / nanocrystals requires stringent requirements and a complex process, which is not suitable for industrial production; second, the controllability of crystal solution growth is poor, which cannot be extended to the microscopic scale and cannot meet the performance requirements of large-area flexible foldable scenarios; third, the excellent optoelectronic properties of perovskite single crystals / nanocrystals formed in the solution phase are difficult to integrate into solid-state optoelectronic devices without loss, which greatly limits the application of perovskite single crystals / nanocrystals in solid-state optoelectronic devices. Summary of the Invention

[0005] This application discloses a method for preparing a perovskite quantum dot conductive film with an epitaxial heterojunction, its products and applications, aiming to solve the technical problems of the two-step growth method for preparing semiconductor epitaxial heterostructures, which is complex and demanding, not suitable for large-scale production, and the large size, rigidity and solid-state integrated photoelectric loss of the formed perovskite single crystals / nanocrystals.

[0006] To achieve the above objectives, the first aspect of the present application provides a method for preparing a perovskite quantum dot conductive film with an epitaxial heterojunction. The preparation method of the present application comprises the following steps:

[0007] providing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand respectively;

[0008] mixing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand to obtain a perovskite heterojunction precursor solution;

[0009] The perovskite heterojunction precursor solution is poured onto the substrate, and film formation and annealing are performed in sequence to obtain a perovskite quantum dot conductive film with an epitaxial heterojunction;

[0010] The first ligand has a structure of formula [i], and the first ligand can interact with the perovskite quantum dot precursor solution to form a zero-dimensional quantum dot:

[0011]

[0012] The second ligand has a structure of formula [ii] or [iii], and the second ligand is capable of interacting with the perovskite matrix precursor to form a two-dimensional or quasi-two-dimensional perovskite:

[0013]

[0014] in, Indicates a connection point;

[0015] Ar is an aromatic ring; R is an aromatic aliphatic branched chain or an alkane aliphatic branched chain;

[0016] X is an isopropylamine cationic side chain or a tert-butylamine cationic side chain;

[0017] Y is one of -F, -Cl, -Br, -I, -CH3, and -OCH3;

[0018] M is an amine-substituted alkane fatty branched chain;

[0019] N is one of -F, -Cl, -Br, -I, and -CH3.

[0020] In some embodiments, the first ligand is a 4-bromo-α,α-dimethyl-benzylamine ligand or a 1-(1-naphthyl)ethylamine ligand;

[0021] The second ligand is one of a phenylethylamine ligand, a 4-bromophenylethylamine ligand, and a butylamine ligand.

[0022] In some embodiments, the perovskite quantum dot precursor solution and the perovskite matrix precursor solution both contain a mixed solvent, and cesium iodide and lead iodide dissolved in the mixed solvent;

[0023] The mixed solvent contains dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of (1-4):1.

[0024] In some embodiments, the molar ratio of cesium iodide to lead iodide in the perovskite quantum dot precursor solution is (0.2-1):1.

[0025] In some embodiments, the molar ratio of cesium iodide to lead iodide in the perovskite matrix precursor solution is (n-1):n, where n≥1.

[0026] In some embodiments, the mass ratio of the first ligand to lead iodide in the perovskite quantum dot precursor solution containing the first ligand is (0.2-1.6):1.

[0027] In some embodiments, when the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand are mixed, the volume ratio of the perovskite quantum dot precursor solution containing the first ligand to the perovskite matrix precursor solution containing the second ligand is (1-7):1.

[0028] In some embodiments, the molar ratio of the first ligand to the second ligand in the perovskite heterojunction precursor solution is (3-7):1.

[0029] In some embodiments, the annealing treatment is performed at a temperature of 70-80° C. and for a time of 8-10 minutes.

[0030] The second aspect of the present application provides a perovskite quantum dot conductive film with an epitaxial heterojunction prepared by the preparation method of the present application.

[0031] The third aspect of the present application provides an application of the perovskite quantum dot conductive film with an epitaxial heterojunction in a solid-state optoelectronic device.

[0032] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present application include at least:

[0033] The preparation method provided by the present application introduces a first ligand into a perovskite quantum dot precursor solution and a second ligand into a perovskite matrix precursor solution and then performs a mixing treatment, thereby utilizing the interaction between the first ligand and the second ligand to efficiently construct an epitaxial heterostructure in one step. On the one hand, it simplifies the preparation steps and removes the limitation of lattice matching of the substrate material, and can enable the precursor solution components to directly in situ crystallize and grow on any substrate (such as SiO2 glass substrate, indium tin oxide conductive glass substrate, quartz substrate, silicon wafer, sapphire, flexible polydimethylsiloxane substrate, flexible polyethylene terephthalate substrate) to form perovskite quantum dots with epitaxial heterojunctions, and is compatible with the preparation process of large-area optoelectronic solid-state films, and is suitable for large-scale industrial production; on the other hand, it can It can avoid the damage to the phase stability of perovskite quantum dots caused by post-treatment in the two-step synthesis step to improve the conductivity of the quantum dot film, so that the prepared perovskite quantum dot conductive film with epitaxial heterojunction can maintain good long-term stability in the natural environment; thirdly, quantum dots of different sizes and uniform size distribution can be obtained by regulating the concentration of the first ligand. Since quantum dots of different sizes have different band gaps, continuous and controllable spectrum adjustment can be achieved, and the adjustment step can be as fine as ~2nm; fourthly, the optoelectronic properties of the perovskite quantum dot conductive film with epitaxial heterojunction can be greatly retained, so that the prepared perovskite quantum dot conductive film with epitaxial heterojunction can be losslessly integrated into solid-state optoelectronic devices, promoting the application of epitaxial heterostructures in solid-state optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some of the embodiments described in this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0035] Figure 1 TEM image of a perovskite quantum dot (CsPbI3) conductive film A with an epitaxial heterojunction provided in an embodiment of the present application;

[0036] Figure 2 The fluorescence intensity of the perovskite quantum dot conductive film A with an epitaxial heterojunction provided in an embodiment of the present application after being placed for different times;

[0037] Figure 3 TEM image of a perovskite quantum dot (CsPbI3) conductive film B with an epitaxial heterojunction provided in an embodiment of the present application;

[0038] Figure 4 TEM image of a perovskite quantum dot (CsPbI3) conductive film C with an epitaxial heterojunction provided in an embodiment of the present application;

[0039] Figure 5 TEM image of a perovskite quantum dot (CsPbI3) conductive film D with an epitaxial heterojunction provided in an embodiment of the present application;

[0040] Figure 6 A physical picture of a large-area (10 cm×10 cm) quantum dot conductive film E with an epitaxial heterojunction provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, B exists alone, and both A and B exist. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0043] In the following description of this embodiment, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0044] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0045] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0046] It will be understood by those skilled in the art that the numerical ranges in the examples of the present application are to be understood as also specifically disclosing each intermediate value between the upper and lower limits of the ranges. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded within the range.

[0047] Unless otherwise indicated, the technical / scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which this application belongs. Although this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

[0048] In a first aspect, an embodiment of the present application provides a method for preparing a perovskite quantum dot conductive film having an epitaxial heterojunction. The preparation method of the embodiment of the present application comprises:

[0049] providing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand respectively;

[0050] mixing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand to obtain a perovskite heterojunction precursor solution;

[0051] The perovskite heterojunction precursor solution is poured onto the substrate, and film formation and annealing are performed in sequence to obtain a perovskite quantum dot conductive film with an epitaxial heterojunction;

[0052] The first ligand has a structure of formula [i], and the first ligand can interact with the perovskite quantum dot precursor solution to form a zero-dimensional quantum dot:

[0053]

[0054] The second ligand has a structure of formula [ii] or [iii], and the second ligand is capable of interacting with the perovskite matrix precursor to form a two-dimensional or quasi-two-dimensional perovskite:

[0055]

[0056] in, Indicates a connection point;

[0057] Ar is an aromatic ring, for example, one of a thiophene ring, a benzene ring, a naphthalene ring, and an anthracene ring;

[0058] R is an aromatic aliphatic branched chain or an alkane aliphatic branched chain, for example, one of propyl, isopropyl, butyl, and isobutyl;

[0059] X is an isopropylamine cationic side chain or a tert-butylamine cationic side chain;

[0060] Y is one of -F, -Cl, -Br, -I, -CH3, and -OCH3;

[0061] M is an amine-substituted alkane aliphatic branched chain, for example, one of a methylamine branched chain, an ethylamine branched chain, an isopropylamine branched chain, and a methylenediamine branched chain;

[0062] N is one of -F, -Cl, -Br, -I, and -CH3.

[0063] The embodiments of the present application achieve efficient and controllable construction of epitaxial heterostructures in one step by rationally designing the ligand chemical structure, thereby improving the phase stability of perovskite quantum dots. Specifically:

[0064] Different choices of organic amine ligands will result in different tendencies for self-assembly to form epitaxial heterostructures. In order to ensure strong coupling between particles and obtain more epitaxial heterostructure particles, the embodiment of the present application selects aromatic compounds with dense stacking and conjugation as precursors for ligand design. On the one hand, by designing the aromatic compound to have an amino head anchoring group, it can be used to interact with the perovskite, wherein the steric hindrance of the chemical structure around the amino head anchoring group is the key to affecting the formation of perovskites of different dimensions. Therefore, in order to achieve perovskite materials with heterogeneous properties, the embodiment of the present application selects aromatic organic amine ligands with different steric hindrances, that is, the tendency to change the perovskite dimension by changing the steric hindrance of the α-carbon adjacent to the amino head group. On the other hand, considering the efficient and effective injection and transport of carriers, the matrix in the heterostructure should have a wider band gap to obtain a type-I energy band arrangement. In the embodiment of the present application, zero-dimensional perovskite quantum dots are selected as the luminescent center perovskite material, and layered perovskite is selected as the wide-bandgap matrix perovskite material, that is, the first ligand X-Ar-Y (X is the head amino anchor group, Ar is the chemical structure skeleton, and Y is the tail group) that induces the luminescent center of the zero-dimensional perovskite quantum dot and the second ligand M-Ar-N / MRN (M is the head amino anchor group, Ar / R is the chemical structure skeleton, and N is the tail group) that induces the layered perovskite matrix are introduced into the perovskite heterojunction precursor solution, thereby utilizing the interaction between the two ligands to induce self-assembly to form an epitaxial heterostructure. Thirdly, there is a strong interaction between the first ligand X-Ar-Y and the second ligand M-Ar-N / MRN, which can obtain a strongly coupled epitaxial heterostructure. By regulating the electron-withdrawing property of the tail group N of the second ligand M-Ar-N / MRN, the density distribution of the π electron cloud of the aromatic ring is affected, and the interaction between the first ligand X-Ar-Y and the second ligand M-Ar-N / MRN is enhanced, thereby enhancing the self-assembly driving force, increasing the tendency to form epitaxial heterostructures, and improving the phase stability of quantum dots in the film.

[0065] Based on the above description, it can be seen that the preparation method provided in the embodiment of the present application introduces a first ligand into the perovskite quantum dot precursor solution and introduces a second ligand into the perovskite matrix precursor solution and then performs a mixing process, thereby utilizing the interaction between the first ligand and the second ligand to efficiently construct an epitaxial heterostructure in one step. On the one hand, the preparation steps are simplified and the limitation of the lattice matching of the substrate material is removed. The precursor solution components can be directly in situ crystallized and grown on any substrate (such as SiO2 glass substrate, indium tin oxide conductive glass substrate, quartz substrate, silicon wafer, sapphire, flexible polydimethylsiloxane substrate, flexible polyethylene terephthalate substrate) to form perovskite quantum dots with epitaxial heterojunctions, and are compatible with the preparation process of large-area optoelectronic solid-state films, and are suitable for large-scale industrial production; On the other hand, it can avoid the damage to the phase stability of the perovskite quantum dots caused by the post-processing operations performed in the two-step synthesis step to improve the conductivity of the quantum dot film, so that the prepared perovskite quantum dot conductive film with epitaxial heterojunction can maintain good long-term stability in the natural environment; thirdly, quantum dots of different sizes and uniform size distribution can be obtained by regulating the concentration of the first ligand. Since quantum dots of different sizes have different band gaps, continuous and controllable spectrum adjustment can be achieved, and the adjustment step size can be refined to ~2nm; fourthly, the optoelectronic properties of the perovskite quantum dot conductive film with epitaxial heterojunction can be greatly retained, so that the prepared perovskite quantum dot conductive film with epitaxial heterojunction can be losslessly integrated into solid-state optoelectronic devices, promoting the application of epitaxial heterostructures in solid-state optoelectronic devices.

[0066] In a specific embodiment, the first ligand is preferably 4-bromo-α,α-dimethyl-benzylamine hydroiodide or 1-(1-naphthyl)ethylamine hydroiodide;

[0067] The second ligand is preferably one of phenethylamine hydroiodide, 4-bromophenethylamine hydroiodide, and butylamine hydroiodide.

[0068] In a specific embodiment, the perovskite quantum dot precursor solution and the perovskite matrix precursor solution both contain a mixed solvent and cesium iodide and lead iodide dissolved in the mixed solvent, wherein the mixed solvent is preferably dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of (1 to 4):1. The volume ratio of dimethyl sulfoxide to N,N-dimethylformamide is specifically 1:1, 2:1, 3:1, 4:1, or any other ratio within this volume ratio range.

[0069] In a specific embodiment, the molar ratio of cesium iodide to lead iodide in the perovskite quantum dot precursor solution is preferably (0.2-1):1. The molar ratio of cesium iodide to lead iodide is specifically any one of 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, and 1:1.

[0070] In a specific embodiment, the molar ratio of cesium iodide to lead iodide in the perovskite matrix precursor solution is preferably (n-1):n, where n is ≥ 1. The molar ratio of cesium iodide to lead iodide can be 0:1, 1:2, 2:3, 3:4, 3:5, etc.

[0071] In a specific embodiment, the molar ratio of the first ligand to lead iodide in the induced perovskite quantum dot precursor solution is preferably (0.2-1.6):1. The molar ratio of the first ligand to lead iodide is specifically 0.2:1, 0.6:1, 1.0:1, 1.4:1, 1.6:1, or any other ratio within the molar ratio range.

[0072] It should be noted that the embodiment of the present application can effectively regulate the particle size of the formed quantum dots by controlling the molar ratio of the first ligand X-Ar-Y and lead iodide (PbI2) in the induced perovskite quantum dot precursor solution, which is convenient, simple and highly controllable.

[0073] In a specific embodiment, when the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand are mixed, the volume ratio of the perovskite quantum dot precursor solution containing the first ligand to the perovskite matrix precursor solution containing the second ligand is preferably (1 to 7): 1. The volume ratio of the perovskite quantum dot precursor solution containing the first ligand to the perovskite matrix precursor solution containing the second ligand can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, or any other ratio within this molar ratio range.

[0074] It should be noted that the embodiments of the present application can effectively control the relative content of quantum dots and matrix in the epitaxial heterostructure by controlling the molar ratio of the perovskite quantum dot precursor containing the first ligand and the perovskite matrix precursor containing the second ligand.

[0075] In a specific embodiment, the molar ratio of the first ligand to the second ligand in the perovskite heterojunction precursor solution is preferably (3-7): 1. The molar ratio of the first ligand to the second ligand is specifically 3:1, 4:1, 5:1, 6:1, 7:1, or any other ratio within the molar ratio range.

[0076] It should be noted that the embodiments of the present application effectively regulate the relative content of quantum dots and matrix in the heterostructure by controlling the molar ratio of the first ligand to the second ligand, thereby ensuring effective injection of carriers and obtaining a highly efficient light-emitting film.

[0077] In a specific embodiment, the annealing temperature is preferably 70-80°C, and the time is preferably 8-10 minutes. The annealing temperature can be 70°C, 72°C, 75°C, 78°C, 80°C, or any one within the temperature range, and the annealing time can be 8 minutes, 9 minutes, 10 minutes, or any one within the time range. The embodiment of the present application effectively controls the crystallization process by controlling the annealing temperature to 70-80°C.

[0078] In the second aspect, the embodiments of the present application provide a perovskite quantum dot conductive film with an epitaxial heterojunction prepared by the preparation method of the present application. Among them, based on the method of the embodiment of the present application, an epitaxial heterostructure can be efficiently constructed in one step, and the damage to the phase stability of the perovskite quantum dots in the two-step synthesis step can be avoided, as well as the photoelectric performance of the perovskite quantum dot conductive film with continuous and controllable spectrum adjustment and great retention of the epitaxial heterojunction can be achieved. Therefore, the perovskite quantum dot conductive film with an epitaxial heterojunction prepared by the embodiment of the present application has excellent photoelectric performance, multi-scenario application prospects, good market competitiveness and good long-term stability in the natural environment.

[0079] Thirdly, embodiments of the present application provide applications of the perovskite quantum dot conductive film with an epitaxial heterojunction in solid-state optoelectronic devices. The perovskite quantum dot conductive film with an epitaxial heterojunction according to the present application exhibits excellent optoelectronic properties and good long-term stability in natural environments. Therefore, when the perovskite quantum dot conductive film with an epitaxial heterojunction according to the embodiments of the present application is used in solid-state optoelectronic devices, the devices can exhibit excellent optoelectronic properties and long-term stability.

[0080] The technical solution of the present application will be further described below in conjunction with specific embodiments.

[0081] Example 1

[0082] This embodiment provides a method for preparing a perovskite quantum dot (CsPbI3) conductive film A having an epitaxial heterojunction, comprising the following steps:

[0083] S101: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0958 g of 4-bromo-α,α-dimethyl-benzylamine hydroiodide in 1 mL of a mixed solvent (DMSO:DMF=4:1). Seal and shake overnight to allow full dissolution. Then, filter using a filter with a pore size of 0.22 μm to obtain a perovskite quantum dot precursor solution containing the first ligand, which is stored in a nitrogen atmosphere until use.

[0084] S102: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0524 g of 4-bromophenylethylamine hydroiodide in 1 mL of a mixed polar solvent (DMSO:DMF=4:1). Seal the container and shake overnight to allow it to fully dissolve. Then, filter the container using a filter with a pore size of 0.22 μm to obtain a perovskite matrix precursor solution containing the second ligand. Store the solution in a nitrogen atmosphere until ready for use.

[0085] S103: Mix the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand in a volume ratio of 5:1, seal and stir or shake overnight to fully mix them, and then obtain the perovskite heterojunction precursor solution, which is stored in a nitrogen atmosphere for later use.

[0086] S104: a 2×2 cm 2 The transparent glass substrate was placed on the spin coater, and after adding 80-120 μL of the perovskite heterojunction precursor solution to the transparent glass substrate, the spin coating time was set to 40 s and the rotation speed was set to 4000 rpm to start the spin coating process.

[0087] S105: After the spin coating is completed, the transparent glass substrate is removed and transferred to a hot stage, the heating temperature is set to 75°C, annealed for 10 minutes, and cooled to obtain a perovskite quantum dot (CsPbI3) conductive film A with an epitaxial heterojunction.

[0088] In order to illustrate the practical effect of the technical solution of this application, the perovskite quantum dot conductive film A with epitaxial heterojunction was tested by transmission electron microscopy (TEM). The results were as follows: Figure 1 As shown. Among them, Figure 1 TEM image of perovskite quantum dot conductive film A with epitaxial heterojunction.

[0089] according to Figure 1 It can be seen that the perovskite quantum dot conductive film A with an epitaxial heterojunction forms perovskite quantum dot particles with a double epitaxial heterojunction, indicating that the present application can utilize the interaction between the first ligand and the second ligand to efficiently construct perovskite quantum dots with an epitaxial heterojunction in one step by introducing a first ligand into the perovskite quantum dot precursor solution and a second ligand into the perovskite matrix precursor solution and then performing a mixing treatment.

[0090] In order to illustrate the stability of the perovskite quantum dot conductive film A with epitaxial heterojunction prepared in Example 1, the present application monitored the fluorescence intensity changes of the perovskite quantum dot conductive film A with epitaxial heterojunction placed in a natural environment for different time periods. The results are as follows: Figure 2 As shown. Among them, Figure 2 The fluorescence intensity of the perovskite quantum dot conductive film A with an epitaxial heterojunction is placed at different times.

[0091] according to Figure 2 It can be seen that the perovskite quantum dot conductive film A with epitaxial heterojunction exhibits good stability.

[0092] Example 2

[0093] This embodiment provides a method for preparing a perovskite quantum dot (CsPbI3) conductive film B with an epitaxial heterojunction, comprising the following steps:

[0094] S201: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0274 g of 4-bromo-α,α-dimethyl-benzylamine hydroiodide in 1 mL of a mixed solvent (DMSO:DMF=4:1), seal and shake overnight to allow it to fully dissolve, and then filter using a filter with a pore size of 0.22 μm to obtain a perovskite quantum dot precursor solution containing the first ligand, which is stored in a nitrogen atmosphere for later use.

[0095] S202: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0397 g of phenylethylamine hydroiodide in 1 mL of a mixed polar solvent (DMSO:DMF=4:1). Seal and shake overnight to allow full dissolution. Filter through a filter with a pore size of 0.22 μm to obtain a perovskite matrix precursor solution containing the second ligand, which is stored in a nitrogen atmosphere for later use.

[0096] S203: Mix the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand in a volume ratio of 5:1, seal and stir or shake overnight to fully mix them, and then obtain the perovskite heterojunction precursor solution, which is stored in a nitrogen atmosphere for later use.

[0097] S204: The 2×2cm 2 The transparent glass substrate was placed on the spin coater, and after adding 80-120 μL of the perovskite heterojunction precursor solution to the transparent glass substrate, the spin coating time was set to 40 s and the rotation speed was set to 4000 rpm to start the spin coating process.

[0098] S205: After the spin coating is completed, the transparent glass substrate is removed and transferred to a hot stage, the heating temperature is set to 70° C., annealing is performed for 10 minutes, and cooling is performed to obtain a perovskite quantum dot (CsPbI 3 ) conductive film C with an epitaxial heterojunction.

[0099] In order to illustrate the practical effect of the technical solution of this application, the perovskite quantum dot conductive film B with epitaxial heterojunction was tested by transmission electron microscopy (TEM). The results are as follows: Figure 3 As shown. Among them, Figure 3TEM image of perovskite quantum dot conductive film B with epitaxial heterojunction.

[0100] according to Figure 3 It can be seen that the perovskite quantum dot conductive film B with an epitaxial heterojunction forms perovskite quantum dot particles with an epitaxial heterostructure with a single interface, indicating that the present application can utilize the interaction between the first ligand and the second ligand to efficiently construct perovskite quantum dots with an epitaxial heterojunction in one step by introducing a first ligand into the perovskite quantum dot precursor solution and a second ligand into the perovskite matrix precursor solution and then performing a mixing treatment.

[0101] Example 3

[0102] This embodiment provides a method for preparing a perovskite quantum dot (CsPbI3) conductive film C with an epitaxial heterojunction, comprising the following steps:

[0103] S301: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0274 g of 4-bromo-α,α-dimethyl-benzylamine hydroiodide in 1 mL of a mixed solvent (DMSO:DMF=4:1), seal and shake overnight to allow it to fully dissolve, and then filter using a filter with a pore size of 0.22 μm to obtain a perovskite quantum dot precursor solution containing the first ligand, which is stored in a nitrogen atmosphere for later use.

[0104] S302: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0320 g of butylamine hydroiodide (second ligand) in 1 mL of a mixed polar solvent (DMSO:DMF=4:1). Seal and shake overnight to allow full dissolution. Filter through a filter with a pore size of 0.22 μm to obtain a perovskite matrix precursor solution containing the second ligand, which is stored in a nitrogen atmosphere for later use.

[0105] S303: Mix the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand in a volume ratio of 5:1, seal and stir or shake overnight to fully mix them, and then obtain the perovskite heterojunction precursor solution, which is stored in a nitrogen atmosphere for later use.

[0106] S304: The 2×2cm 2 The transparent glass substrate was placed on the spin coater, and after adding 80-120 μL of the perovskite heterojunction precursor solution to the transparent glass substrate, the spin coating time was set to 40 s and the rotation speed was set to 4000 rpm to start the spin coating process.

[0107] S305: After the spin coating is completed, the transparent glass substrate is removed and transferred to a hot stage, the heating temperature is set to 80°C, annealed for 8 minutes, and cooled to obtain a perovskite quantum dot (CsPbI3) conductive film C with an epitaxial heterojunction.

[0108] In order to illustrate the practical effect of the technical solution of this application, the perovskite quantum dot conductive film C with epitaxial heterojunction was tested by transmission electron microscopy (TEM). The results are as follows: Figure 4 As shown. Among them, Figure 4 TEM image of the perovskite quantum dot conductive film C with epitaxial heterojunction.

[0109] according to Figure 4 It can be seen that the perovskite quantum dot conductive film C with an epitaxial heterojunction forms perovskite quantum dot particles with an epitaxial heterostructure with a single interface, indicating that the present application can utilize the interaction between the first ligand and the second ligand to efficiently construct perovskite quantum dots with an epitaxial heterojunction in one step by introducing a first ligand into the perovskite quantum dot precursor solution and a second ligand into the perovskite matrix precursor solution and then performing a mixing treatment.

[0110] Example 4

[0111] This embodiment provides a method for preparing a perovskite quantum dot (CsPbI3) conductive film D having an epitaxial heterojunction, comprising the following steps:

[0112] S401: Dissolve 0.0234 g of CsI, 0.0922 g of PbI2 and 0.0838 g of 1-(1-naphthyl)ethylamine hydroiodide in 1 mL of a mixed solvent (DMSO:DMF=4:1). Seal and shake overnight to allow full dissolution. Then, filter using a filter with a pore size of 0.22 μm to obtain a perovskite quantum dot precursor solution containing the first ligand, which is stored in a nitrogen atmosphere for later use.

[0113] S402: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0524 g of 4-bromophenylethylamine hydroiodide in 1 mL of a mixed polar solvent (DMSO:DMF=4:1). Seal and shake overnight to allow full dissolution. Filter through a filter with a pore size of 0.22 μm to obtain a perovskite matrix precursor solution containing the second ligand, which is stored in a nitrogen atmosphere until use.

[0114] S403: Mix the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand in a volume ratio of 5:1, seal and stir or shake overnight to fully mix them, and then obtain the perovskite heterojunction precursor solution, which is stored in a nitrogen atmosphere for later use.

[0115] S404: The 2×2cm 2 The transparent glass substrate was placed on the spin coater, and after adding 80-120 μL of the perovskite heterojunction precursor solution to the transparent glass substrate, the spin coating time was set to 40 s and the rotation speed was set to 4000 rpm to start the spin coating process.

[0116] S405: After the spin coating is completed, the transparent glass substrate is removed and transferred to a hot stage, the heating temperature is set to 75°C, annealed for 10 minutes, and cooled to obtain a perovskite quantum dot (CsPbI3) conductive film D with an epitaxial heterojunction.

[0117] In order to illustrate the practical effect of the technical solution of this application, the perovskite quantum dot conductive film D with epitaxial heterojunction was tested by transmission electron microscopy (TEM). The results are as follows: Figure 5 As shown. Among them, Figure 5 TEM image of perovskite quantum dot conductive film D with epitaxial heterojunction.

[0118] according to Figure 5 It can be seen that the perovskite quantum dot conductive film D with an epitaxial heterojunction forms perovskite quantum dot particles with multiple epitaxial interfaces, and the perovskite quantum dot particles with a double epitaxial heterojunction are dominant. This indicates that the present application can utilize the interaction between the first ligand and the second ligand to efficiently construct perovskite quantum dots with an epitaxial heterojunction in one step by introducing a first ligand into the perovskite quantum dot precursor solution and a second ligand into the perovskite matrix precursor solution and then performing a mixing treatment.

[0119] Example 5

[0120] This embodiment provides a method for preparing a large-area conductive film E of perovskite quantum dots (CsPbI3) with an epitaxial heterojunction, comprising the following steps:

[0121] S501: Dissolve 0.0312 g of CsI, 0.0922 g of PbI2 and 0.0958 g of 4-bromo-α,α-dimethyl-benzylamine hydroiodide in 1 mL of a mixed solvent (DMSO:DMF=4:1), seal and shake overnight to fully dissolve it, and then filter it through a filter with a pore size of 0.22 μm to obtain a perovskite quantum dot precursor solution containing the first ligand, which is stored in a nitrogen atmosphere for later use.

[0122] S502: Dissolve 0.0260 g of CsI, 0.0922 g of PbI2 and 0.0654 g of 4-bromophenylethylamine hydroiodide in 1 mL of a mixed polar solvent (DMSO:DMF=4:1). Seal and shake overnight to allow for full dissolution. Filter through a filter with a pore size of 0.22 μm to obtain a perovskite matrix precursor solution containing the second ligand, which is stored in a nitrogen atmosphere until use.

[0123] S503: Mix the perovskite quantum dot precursor solution containing the first ligand and the perovskite matrix precursor solution containing the second ligand in a volume ratio of 5:1, seal and stir or shake overnight to fully mix them, and then obtain the perovskite heterojunction precursor solution, which is stored in a nitrogen atmosphere for later use.

[0124] S504: Control the air humidity during scraping to ≤25% and the ambient temperature to ≤20℃. 2 The transparent glass substrate is placed on the scraping instrument platform, and the height between the device for loading the perovskite heterojunction precursor liquid and the glass substrate is set to 2-3 μm, the corresponding movement speed is 130-150 mm / s, the nitrogen scraper speed is 50-60 mm / s, the nitrogen pressure is 0.2 MPa, and the scraping process begins.

[0125] S505: After the coating is completed, the transparent glass substrate is removed and transferred to a hot stage, the heating temperature is set to 80° C., annealing is performed for 8 minutes, and cooling is performed to obtain a perovskite quantum dot (CsPbI 3 ) conductive film E with an epitaxial heterojunction.

[0126] To illustrate the practical effect of the technical solution of this application, a large area (10×10 cm 2 ) conductive film E, the result is Figure 6 As shown. Among them, Figure 6 For large-area (10×10cm) perovskite quantum dots with epitaxial heterojunction 2 ) Actual picture of conductive film E.

[0127] according to Figure 6 It can be seen that the perovskite quantum dot conductive film E with an epitaxial heterojunction exhibits bright red fluorescence, and the luminescence peak of the film is located at ~640nm, indicating that the fluorescence emitted by the perovskite quantum dot conductive film E with an epitaxial heterojunction is in the pure red light region, with uniform luminescence and high color purity.

[0128] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0129] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for preparing a perovskite quantum dot conductive film with an epitaxial heterojunction, characterized in that: The method comprises: providing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand respectively; mixing a perovskite quantum dot precursor solution containing a first ligand and a perovskite matrix precursor solution containing a second ligand to obtain a perovskite heterojunction precursor solution; The perovskite heterojunction precursor solution is poured onto the substrate, and film formation and annealing are performed in sequence to obtain a perovskite quantum dot conductive film with an epitaxial heterojunction; The first ligand is 4-bromo- α , α -dimethyl-benzylamine hydroiodide or 1-(1-naphthyl)ethylamine hydroiodide; the second ligand is one of phenylethylamine hydroiodide, 4-bromophenylethylamine hydroiodide, and butylamine hydroiodide; The perovskite quantum dot precursor solution and the perovskite matrix precursor solution both contain dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of (4-1):1, as well as cesium iodide and lead iodide, and the molar ratio of cesium iodide to lead iodide is 0.6:1; The molar ratio of the first ligand to lead iodide in the perovskite quantum dot precursor solution is (0.2-1.6):1; the molar ratio of the first ligand to the second ligand is (3-7):

1.

2. The preparation method according to claim 1, characterized in that The annealing temperature is 70-80°C and the time is 8-10 min.

3. A perovskite quantum dot conductive film with an epitaxial heterojunction prepared according to the method of claim 1 or 2.

4. Use of the perovskite quantum dot conductive film with epitaxial heterojunction according to claim 3 in solid-state optoelectronic devices.

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