Preparation method of hexagonal boron nitride modified perovskite heterostructure and application of hexagonal boron nitride modified perovskite heterostructure in improvement of PSCs thermal management

Abstract

The invention provides a preparation method of a hexagonal boron nitride modified perovskite heterostructure and application of the hexagonal boron nitride modified perovskite heterostructure in improvement of PSCs thermal management. A perovskite precursor solution used for preparing a photoactive layer is improved, and ester modified hexagonal boron nitride molecules are added into the perovskite precursor solution. Effective coupling of hexagonal boron nitride and perovskite crystal lattices is enhanced through coordination of ester, the intrinsic thermal conductivity characteristic of hexagonal boron nitride is reserved, heat distribution in a device is optimized by constructing an efficient heat dissipation network, effective heat dissipation is promoted, the effectiveness of the device in the aspect of long-term stability is further improved, and the performance of the device is improved. And the heat conduction performance of the perovskite thin film is improved, so that the preparation of the high-temperature stable perovskite solar cell is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic chemical materials and relates to perovskite solar cells, and specifically to a method for preparing a hexagonal boron nitride-modified perovskite heterostructure and its application in preparing perovskite solar cells (PSCs) with efficient thermal management. Background Art

[0002] Perovskite solar cells (PSCs), a representative of third-generation photovoltaic technology, have achieved power conversion efficiencies (PCEs) exceeding 27.0%, demonstrating performance potential comparable to crystalline silicon cells. However, long-term device stability, particularly performance degradation under high-temperature conditions, has become a key bottleneck restricting their commercial application. Research has shown that the temperature rise caused by the photothermal effect during PSC operation (e.g., device temperatures can reach above 65°C under actual operating conditions) significantly accelerates material degradation kinetics. For example, Jiang et al. reported that the T80 lifetime (the time required for the efficiency to decay to 80% of the initial value) of pin-type PSCs at 85°C was only 360 hours, nearly 40 times lower than the 14,580 hours at 25°C, highlighting the crucial role of temperature on stability. This thermally induced degradation is primarily due to the thermally activated diffusion of halide ions in the perovskite lattice, the volatilization of organic components, and the enhanced non-radiative recombination at interfaces, ultimately leading to irreversible degradation of device performance.

[0003] In response to the above problems, developing efficient thermal management strategies to reduce the operating temperature of the device is a key way to improve the operational stability of PSCs. Hexagonal boron nitride is considered to be an ideal heat dissipation enhancement material due to its high thermal conductivity, wide band gap and chemical inertness. However, the uniform dispersion of hexagonal boron nitride in the perovskite matrix and its compatibility with photogenerated carrier transport still face challenges. Existing studies mostly use physical blending methods to introduce hexagonal boron nitride, but it is easy to cause interface defects and charge recombination, which restricts efficiency improvement. Therefore, how to construct a hexagonal boron nitride / perovskite heterostructure with synergistic optimization of efficient heat dissipation and charge transport is a difficulty in current research. Summary of the Invention

[0004] The present invention is directed to the above-mentioned problems and provides a method for preparing a hexagonal boron nitride-modified perovskite heterostructure and its application in the preparation of related perovskite solar cells to improve their thermal stability and thermal conductivity.

[0005] The research concept of this invention is as follows: the perovskite precursor solution used to prepare the photoactive layer is improved by adding ester-modified hexagonal boron nitride molecules to the perovskite precursor solution. The ester's coordination effect enhances the effective coupling between the hexagonal boron nitride and the perovskite lattice while retaining the intrinsic thermal conductivity of the hexagonal boron nitride. By constructing an efficient heat dissipation network, this method optimizes heat distribution within the device and promotes efficient heat dissipation, thereby enhancing the device's long-term stability and improving the thermal conductivity of the perovskite film, thereby enabling the preparation of high-temperature stable perovskite solar cells.

[0006] Based on the above research, the technical solutions specifically adopted in the present invention are as follows:

[0007] In a first aspect, the present invention provides a method for preparing a hexagonal boron nitride-modified perovskite heterostructure, wherein an ester-modified functionalized hexagonal boron nitride solution is added to a perovskite precursor solution, mixed to prepare an improved perovskite precursor solution, and spin-coated on a hole transport layer of a perovskite solar cell, and heated and annealed to obtain a perovskite film as a perovskite absorption layer.

[0008] Preferably, the perovskite precursor is selected from any one of the following materials: Cs x FA y MA 1-x-y Pb(I z Br 1-z )3, where x is 0~1, y is 0~1, and z is 0~1; CH3NH3PbI3; MAPb x Sn 1-x I3, where x is 0 to 1; CH(NH2)2PbI3; FAPb x Sn 1- x I3, where x is 0~1; Cs x MA 1-x Pb(I y Br 1-y )3, where x is 0~1, y is 0~1; Cs x FA 1-x Pb(I y Br 1-y )3, where x is 0~1; y is 0~1; FA x MA 1-x Pb(I y Br 1-y )3, where x is 0~1; y is 0~1; CsPb(I x Br 1-x )3, where x is 0~1; CsSn(I x Br 1-x)3, where x is 0 to 1; (PEA)2(MA) n-1 Pb n I 3n+1 , where n is an integer starting from 1.

[0009] More preferably, Cs x FA y MA 1-x-y Pb(I z Br 1-z )3 perovskite precursor solution, the preparation method comprises the following steps: dissolving cesium iodide, methylamine bromide, lead bromide, formamidine hydroiodide, and lead iodide powder in a molar ratio of 1:1~5:0.05~5:1~30:1~30 in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide being 2~8:1, stirring at room temperature overnight to obtain the Cs x FA y MA 1-x-y Pb(I z Br 1-z )3 solution.

[0010] The most preferred 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 The preparation method of the perovskite precursor solution comprises the following steps: dissolving cesium iodide, methylamine bromide, lead bromide, formamidine hydroiodide, and lead iodide powder in a molar ratio of 1:2:3.1:16.2:16.9 in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide, wherein the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is 2-8:1, and stirring at room temperature overnight to obtain the Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 of solution.

[0011] Preferably, the ester-modified functionalized hexagonal boron nitride is hexagonal boron nitride prepared based on the ester-assisted ball milling method, and its mass fraction in the improved perovskite precursor solution is 7%, and its solvent is at least one of the perovskite precursor solvents, such as N,N-dimethylformamide.

[0012] Furthermore, the ester is selected from any one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, ethyl acetate, ethylene carbonate, propylene carbonate, trimethyl citrate, and ethylene glycol oxalate.

[0013] The specific steps of the ester-assisted ball milling method are as follows: micron-sized hexagonal boron nitride powder and ester are added to a steel grinding jar containing 8 mm diameter steel balls in a mass ratio of 1:4, maintaining the ball-to-powder mass ratio at 50:1; the ball mill speed is set to 400 rpm, and the ball milling is continued for 12 hours. After the ball milling is completed, the product is collected and repeatedly washed with deionized water and ethanol until the pH value is close to neutral; the sample is placed in a vacuum oven for drying and then dispersed in ethanol and ultrasonically treated for 1 hour to obtain a uniformly dispersed hexagonal boron nitride solution. The dispersed hexagonal boron nitride solution is then centrifuged at 2000 rpm for 30 minutes to remove agglomerates and thick layer materials. The supernatant after centrifugation is the final product.

[0014] In a second aspect, the present invention provides a perovskite solar cell having a structure, from bottom to top, comprising: a conductive substrate layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a back electrode. The perovskite light-absorbing layer is a functionalized hexagonal boron nitride-doped perovskite film, prepared as described above in the first aspect.

[0015] Preferably, the material of the conductive substrate layer is selected from FTO conductive glass or ITO conductive glass, wherein the thickness of the substrate is 1-2 mm and the layer thickness is 200-600 nm;

[0016] The thickness of the hole transport layer is 10-50 nm, and the material is selected from any one of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), poly(3,4-ethylenedioxythiophene) (PEDOT:PSS), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)]amine (PTAA);

[0017] The thickness of the perovskite light-absorbing layer is 500-1500 nm;

[0018] The thickness of the electron transport layer is 20 nm, and the material is selected from [6,6]-phenyl-C 61 -Methyl butyrate ([6,6]-Phenyl-C 61 -butyric acid methyl ester, PC 61 BM);

[0019] The hole blocking layer has a thickness of 5 nm and is made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Bathocuproine, BCP).

[0020] The thickness of the back electrode is 100 nm and the material is selected from silver.

[0021] In a third aspect, the present invention provides a method for preparing the above-mentioned perovskite solar cell, comprising the following steps:

[0022] Step (1), spin coating a hole transport layer material solution on the surface of a clean conductive substrate layer, which serves as the hole transport layer;

[0023] Step (2), spin-coating the perovskite precursor solution on the hole transport layer prepared above in an inert atmosphere to form a perovskite light absorbing layer film, which serves as the perovskite light absorbing layer;

[0024] Step (3), spin coating an electron transport layer material solution on the surface of the perovskite light absorbing layer, and the layer serves as the electron transport layer;

[0025] Step (4), spin coating a hole blocking layer material solution on the surface of the electron transport layer, and the layer serves as a hole blocking layer;

[0026] Step (5): evaporating metal on the hole blocking layer to serve as a back electrode.

[0027] Preferably, in step (1), the conductive substrate layer is treated as follows: the conductive substrate is ultrasonically cleaned three times in sequence with deionized water, acetone, and ethanol, and then dried to completely remove the solvent and moisture; the cleaned conductive substrate is dried and treated with ultraviolet ozone for 10 to 30 minutes, and the layer is used as the conductive substrate layer; the hole transport layer material solution is spin-coated under the following conditions: 3000 rpm, 30 seconds, and heated and annealed at a temperature of 80 to 130 ° C for 3 to 20 minutes;

[0028] In step (2), the spin coating conditions of the perovskite precursor solution are as follows: 1000 rpm, 5 s, 4000 rpm, 20 s; heating at a temperature of 80-130 °C for 5-40 min;

[0029] In step (3), the spin coating conditions for the electron transport layer material solution are as follows: 2000 rpm, 45 s;

[0030] In step (4), the conditions for spin coating the hole blocking layer material solution are as follows: 4000 rpm, 45 s; heating at a temperature of 60~90°C for 5~20 min.

[0031] Furthermore, the hole transport layer material solution is prepared by: dissolving the hole transport layer material in anhydrous ethanol to form a hole transport layer material solution with a concentration of 0.1 to 1 mg / mL;

[0032] The preparation method of the electron transport layer material solution is as follows: dissolving the electron transport layer material in chlorobenzene to form an electron transport layer material solution with a concentration of 20 mg / mL;

[0033] The hole blocking layer material solution is prepared by dissolving the hole blocking layer material in anhydrous ethanol to form a hole blocking layer material solution with a concentration of 0.5 mg / mL.

[0034] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0035] The perovskite solar cell prepared by this method exhibits excellent thermal stability. After 2640 hours of aging testing at 85°C under continuous illumination, the device still maintained over 95% of its initial efficiency. This result fully demonstrates the effectiveness of ester-modified hexagonal boron nitride in improving the long-term stability of the device.

[0036] The introduction of ester-modified hexagonal boron nitride significantly improves the thermal conductivity of the perovskite film. Thermal conductivity measurements show that ester-modified hexagonal boron nitride increases the thermal conductivity of the perovskite film by 30.7% and reduces the device operating temperature by 12.9°C (under one-sun illumination). Finite element analysis further confirms that ester-modified hexagonal boron nitride optimizes heat distribution within the device by creating a highly efficient heat dissipation network, promoting efficient heat dissipation.

[0037] In the perovskite solar cell prepared by the present invention, the perovskite absorption layer is applicable to a variety of different types of perovskite layers, such as CH3NH3PbI3, MAPb x Sn 1-x I3、Cs x FA y MA 1-x-y Pb(I z Br 1-z )3, etc., and has wide applicability.

[0038] The hexagonal boron nitride and ester compounds used in the present invention are both commercial products and do not require further processing, thus having high practicality and operability.

[0039] The present invention adopts a simple layer-by-layer coating method, which makes the preparation process simple and economical, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of scanning electron microscopy of hexagonal boron nitride prepared in Example 1. a and b are the morphologies of BN-0 and BN-1, respectively.

[0041] Figure 2 Figures 1 and 2 are schematic scanning electron micrographs of the perovskite light-absorbing layer films prepared in Example 1 and Comparative Example 1. Figure a shows the morphology of the perovskite light-absorbing layer film undoped with hexagonal boron nitride; b shows the morphology of the perovskite light-absorbing layer film doped with BN-0; and c shows the morphology of the perovskite light-absorbing layer film doped with BN-1.

[0042] Figure 3 Schematic diagram of thermal conductivity data of the perovskite light-absorbing layer films prepared in Example 1 and Comparative Example 1.

[0043] Figure 4 Schematic diagram of the current density-voltage curves obtained in the reverse scanning mode for the perovskite solar cells prepared in Example 1 and Comparative Example 1.

[0044] Figure 5 1 is a schematic diagram showing the long-term operational stability of the perovskite solar cells prepared in Example 1 and Comparative Example 1, as evaluated by tracking their maximum power points under continuous one-sun illumination at 85°C. DETAILED DESCRIPTION

[0045] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] " Scope " disclosed herein is in the form of lower limit and upper limit. Can be respectively one or more lower limits, and one or more upper limits. A given range is limited by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges that can be limited in this way are inclusive and combinable, i.e. any lower limit can be combined with any upper limit to form a range. For example, for a particular parameter, a range of 100 ~ 140 and 500 ~ 900 is listed, and it is understood that a range of 100 ~ 140 and 500 ~ 900 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range 3,4 and 5 are listed, then the following ranges can all be expected: 1 ~ 2, 1 ~ 4, 1 ~ 5, 2 ~ 3, 2 ~ 4 and 2 ~ 5.

[0047] In this disclosure, unless otherwise specified, the numerical range "a to b" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0" and "5" are listed herein, and "0 to 5" is merely an abbreviation for these numerical combinations.

[0048] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0049] Example 1 Preparation of perovskite solar cells

[0050] Step 1: Preparation of ester-modified hexagonal boron nitride

[0051] Micron-sized hexagonal boron nitride powder and trimethyl phosphate were added to a steel grinding jar containing 8 mm diameter steel balls (the mass ratio of hexagonal boron nitride to trimethyl phosphate was 1:4), maintaining a ball-to-powder ratio of 50:1. The planetary ball mill was set to 400 rpm and milling was continued for 12 hours. After milling, the product was collected and repeatedly washed with deionized water and ethanol until the pH reached near neutral. The sample was then dried in a vacuum oven. The dried sample was dispersed in ethanol and sonicated for 1 hour to obtain a uniformly dispersed hexagonal boron nitride solution. The dispersed hexagonal boron nitride solution was centrifuged at 2000 rpm for 30 minutes to remove agglomerates and thick flakes. The supernatant after centrifugation was the final product. After removing the ethanol, the hexagonal boron nitride sample obtained was designated BN-1. As a control, an untreated hexagonal boron nitride sample was designated BN-0.

[0052] Step 2: Preparation of perovskite precursor solution and charge transport layer material solution

[0053] Preparation of hole transport layer material solution:

[0054] 2PACz (1.1 × 10 -6 mol, 0.3 mg) was dissolved in 1 mL of anhydrous ethanol and stirred overnight to obtain a 0.3 mg / mL 2PACz solution.

[0055] Preparation of perovskite precursor solution:

[0056] Cesium iodide (0.07 mol, 18.2 mg), methylamine bromide (0.14 mol, 21.9 mg), lead bromide (0.217 mol, 79.6 mg), formamidine hydroiodide (1.134 mol, 195.1 mg), and lead iodide powder (1.183 mol, 545.4 mg) were dissolved in 1 mL of a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide (the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide was 4:1). The mixture was stirred at room temperature overnight to obtain a Cs solution with a concentration of 1.4 mol / L. 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 Perovskite precursor solution. A solution of BN-1 in N,N-dimethylformamide was added to the perovskite precursor solution to a concentration of 7% to achieve uniform distribution of BN-1 in the perovskite film.

[0057] Preparation of electron transport layer material solution:

[0058] Using [6,6]-phenyl-C 61 -Methyl butyrate ([6,6]-Phenyl-C 61 -butyric acid methylester, PC 61 BM) as the electron transport layer material.

[0059] PC 61 BM (2×10 -5 mol, 20 mg) was dissolved in 1 mL of chlorobenzene and stirred at room temperature for 24 h to obtain PC 61 BM solution, namely electron transport layer material solution.

[0060] 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Bathocuproine, BCP) (1×10 -6 mol, 0.5 mg) was dissolved in 1 mL of anhydrous ethanol and stirred at room temperature for 24 h to obtain a BCP solution, i.e., a hole blocking layer material solution.

[0061] Step 3: Preparation of perovskite solar cells

[0062] The cleaning steps of the conductive substrate are: the conductive substrate is repeatedly ultrasonically cleaned three times in sequence with deionized water, acetone, and ethanol, and then dried until the solvent and moisture are completely removed.

[0063] The cleaned ITO conductive glass (Nippon Sheet Glass, Wuhan Jingge Solar Technology Co., Ltd., 8 Ω / m 2 , length × width = 1.5 cm × 1.3 cm, glass substrate thickness of 1 mm, conductive layer thickness of 300 nm) and dried, and treated with UV-ozone cleaning machine for 20 min. This layer was used as the conductive glass substrate layer.

[0064] The hole transport layer material solution 2PACz solution was spin-coated on a clean ITO surface. The spin-coating parameters were: 3000 rpm, 30 s, heating annealing at 100 °C for 10 min, and the thickness was 20 nm. This layer served as the hole transport layer.

[0065] 50 μL of BN-1 doped Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45The perovskite precursor solution was spin-coated onto the prepared hole transport layer at the following spin-coating parameters: 1000 rpm for 5 seconds, then 4000 rpm for 20 seconds. The solution was then heated at 100°C for 30 minutes to form a perovskite light-absorbing layer. The perovskite absorber layer, prepared in a nitrogen glove box, had a thickness of 550 nm and served as the perovskite light-absorbing layer.

[0066] Spin-coat the electron transport layer material solution, PC, on the surface of the perovskite light absorbing layer. 61 BM solution, spin coating parameters are: 2000 rpm, 45 s; thickness is 20 nm, this layer serves as the electron transport layer.

[0067] The hole blocking layer material, namely BCP solution, was spin-coated on the surface of the electron transport layer. The spin-coating parameters were: 4000 rpm, 45s; heated at 70 °C for 15 min, and the thickness was 5 nm. This layer served as the hole blocking layer.

[0068] Metal silver was evaporated on the hole blocking layer using an evaporation apparatus with a thickness of 100 nm as the back electrode.

[0069] The fabricated perovskite solar cell has the following structure, from bottom to top: a conductive glass substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a back electrode. The glass substrate is 1 mm thick, the conductive layer is 300 nm thick, the hole transport layer is 20 nm thick, the perovskite light-absorbing layer is 550 nm thick, the electron transport layer is 20 nm thick, the hole blocking layer is 5 nm thick, and the back electrode is 100 nm thick.

[0070] Comparative Example 1 Preparation of non-hexagonal boron nitride-doped perovskite solar cell:

[0071] The cleaned ITO conductive glass (Wuhan Jingge Solar Technology Co., Ltd., 8 Ω / m 2 , length × width = 1.5 cm × 1.3 cm, glass substrate thickness of 1 mm, conductive layer thickness of 300 nm) and dried, and treated with UV ozone cleaning machine for 20 min. This layer was used as the conductive glass substrate layer.

[0072] The hole transport layer material solution 2PACz solution was spin-coated on a clean ITO surface. The spin-coating parameters were: 3000 rpm, 30 s, heating annealing at 100 °C for 10 min, and a thickness of 20 nm. This layer served as the hole transport layer.

[0073] 50 μL Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br0.45 The perovskite precursor solution was spin-coated onto the prepared hole transport layer at the following spin-coating parameters: 1000 rpm for 5 seconds, then 4000 rpm for 20 seconds. The solution was then heated at 100°C for 30 minutes to form a perovskite light-absorbing layer. The perovskite absorber layer, prepared in a nitrogen glove box, had a thickness of 550 nm and served as the perovskite light-absorbing layer.

[0074] Spin-coat the electron transport layer material solution, PC, on the surface of the perovskite light absorbing layer. 61 BM solution, spin coating parameters are: 2000 rpm, 45 s; thickness is 20 nm, this layer serves as the electron transport layer.

[0075] The hole blocking layer material, namely BCP solution, was spin-coated on the surface of the electron transport layer. The spin-coating parameters were: 4000 rpm, 45 s; heated at 70 °C for 15 min, and the thickness was 5 nm. This layer served as the hole blocking layer.

[0076] Metal silver was evaporated on the hole blocking layer using an evaporation apparatus with a thickness of 100 nm as the back electrode.

[0077] The fabricated perovskite solar cell has the following structure, from bottom to top: a conductive glass substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a back electrode. The glass substrate is 1 mm thick, the conductive layer is 300 nm thick, the hole transport layer is 20 nm thick, the perovskite light-absorbing layer is 550 nm thick, the electron transport layer is 20 nm thick, the hole blocking layer is 5 nm thick, and the back electrode is 100 nm thick.

[0078] Effect comparison

[0079] 1. Morphology Characterization and Thermal Conductivity Comparison

[0080] Figure 1 This is a scanning electron micrograph of the hexagonal boron nitride prepared in Example 1. a and b show the morphologies of BN-0 and BN-1, respectively. The image shows clear separation between the layers of the ester-modified hexagonal boron nitride (BN-1), facilitating thorough mixing with the perovskite precursor solution.

[0081] Figure 2Figures 1 and 2 are scanning electron micrographs of the perovskite light-absorbing layer films prepared in Example 1 and Comparative Example 1. Figure a shows the morphology of the perovskite light-absorbing layer film undoped with hexagonal boron nitride; b shows the morphology of the perovskite light-absorbing layer film doped with BN-0; and c shows the morphology of the perovskite light-absorbing layer film doped with BN-1. The figures show that both BN-0 and BN-1-doped perovskite films contain nanoscale lamellae structures, while the lamellae formed by BN-1 are more uniform. This structure forms an effective heat conduction channel, which helps improve the thermal management capabilities of the perovskite film and device.

[0082] Figure 3 The thermal conductivity data of the perovskite light absorbing layer films prepared in Example 1 and Comparative Example 1 are shown in FIG. The results show that the thermal conductivity of the undoped perovskite film is 0.26 W m -1 K -1 The thermal conductivity of the BN-0 doped perovskite film is 0.31 W m -1 K -1 The thermal conductivity of the BN-1 doped perovskite film is 0.34 W m -1 K -1 The ester-modified hexagonal boron nitride increased the thermal conductivity of the perovskite film by 30.8%.

[0083] II. Performance Characterization Test of Perovskite Solar Cells Prepared in Example 1 and Comparative Example 1

[0084] The assembled perovskite solar cells were subjected to a solar simulator at 100 mW cm -2 The photoelectric conversion efficiency was tested under standard light. The effective area of ​​the cell is 0.0625 cm 2 . Figure 4 Schematic diagram of the current density-voltage (J-V) curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1 obtained in the reverse scanning mode, with photoelectric conversion efficiencies of 23.47% and 21.66%, respectively.

[0085] Power conversion efficiency (PCE) is the most fundamental and core parameter for evaluating solar cells. It can be calculated from the current-voltage (IV) curve obtained by testing the cell under AM 1.5G standard solar irradiation conditions. The calculation formula is as follows:

[0086] (1.1)

[0087] Among them, P in Indicates the incident light power density (intensity of incident light). SCis the short-circuit photocurrent density, that is, the current density when the circuit is in a short-circuit state, at which time the battery voltage is 0 V. V OC is the open-circuit photovoltage, which is the potential difference across the battery measured when the battery is in the open circuit state. At this moment, the current flowing through the circuit is 0 A. FF is the fill factor, which is determined by the maximum power per unit area of ​​the solar cell (P max ) divided by V OC and J SC The ratio of is calculated and takes values ​​in the range of 0 to 1, as shown in formula (1.2).

[0088] (1.2)

[0089] Photovoltaic conversion efficiency is the most important parameter for evaluating solar cell performance. Before testing, a solar simulator (Solar IV-150A, Zolix) was used to simulate a standard sunlight AM 1.5G (100 mW cm -2 ) was used as the light source to illuminate the solar cell. The light intensity was calibrated using a standard Newport calibrated KG5 filtered silicon reference cell. A Keithley 2400 digital source meter was used in a normal working environment at 0.15 V s -1 The J-V curves of the devices were measured at a scan rate (voltage sweep range of -0.2 to 1.3 V with a step size of 10 mV). The active area of ​​the device was limited to 0.0625 cm using a metal mask. 2 .

[0090] Figure 5 The figure shows the long-term operational stability of the perovskite solar cells prepared in Example 1 and Comparative Example 1, as assessed by tracking their maximum power point (MPP) under continuous one-sun illumination at 85°C. The graph shows that after 2540 hours of continuous operation, the perovskite solar cell prepared in Example 1 maintained over 95% of its initial efficiency, while the perovskite solar cell prepared in Comparative Example 1 rapidly degraded to 63.5% of its initial performance after 585 hours of continuous operation. These results demonstrate that the introduction of BN-1 optimizes the device's thermal management capabilities and improves its operational stability under high-temperature conditions.

[0091] Examples 2 to 4 are variations of Example 1. Some materials in Example 1 are equivalently replaced. In Example 2, the ester used to modify hexagonal boron nitride is replaced with ethylene glycol oxalate. In Example 3, the conductive substrate glass is replaced. In Example 4, the back electrode is replaced. Similar technical effects can be achieved. The details are as follows:

[0092] Example 2

[0093] Step 1: Preparation of ester-modified hexagonal boron nitride

[0094] 0.2 g of micron-sized hexagonal boron nitride powder and 0.8 g of ethylene glycol oxalate were added to a steel grinding jar containing 8 mm diameter steel balls, maintaining a ball-to-powder mass ratio of 50:1. The planetary ball mill was set to 400 rpm and milling was continued for 12 hours. After ball milling, the product was collected and repeatedly washed with deionized water and ethanol until the pH value was close to neutral. The sample was then dried in a vacuum oven. The dried sample was dispersed in ethanol and sonicated for 1 hour to obtain a uniformly dispersed hexagonal boron nitride solution. The dispersed hexagonal boron nitride solution was centrifuged at 2000 rpm for 30 minutes to remove agglomerates and thick flakes. The supernatant after centrifugation was the final product, designated BN-2. As a control, an untreated hexagonal boron nitride sample was designated BN-0.

[0095] Step 2: Preparation of perovskite precursor solution and charge transport layer material solution

[0096] Preparation of hole transport layer material solution:

[0097] 2PACz (1.1 × 10 -6 mol, 0.3 mg) was dissolved in 1 mL of anhydrous ethanol and stirred overnight to obtain a 0.3 mg / mL 2PACz solution;

[0098] Preparation of perovskite precursor solution:

[0099] Cesium iodide (0.07 mol, 18.2 mg), methylamine bromide (0.14 mol, 21.9 mg), lead bromide (0.217 mol, 79.6 mg), formamidine hydroiodide (1.134 mol, 195.1 mg), and lead iodide powder (1.183 mol, 545.4 mg) were dissolved in 1 mL of a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide (the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide was 4:1). The mixture was stirred at room temperature overnight to obtain a Cs solution with a concentration of 1.4 mol / L. 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 Perovskite precursor solution: Add a solution of BN-2 in N,N-dimethylformamide to the perovskite precursor solution to a concentration of 7% to achieve uniform distribution of BN-2 in the perovskite film.

[0100] Preparation of electron transport layer material solution:

[0101] Using PC 61 BM is used as the electron transport layer material.

[0102] PC 61 BM (2×10 -5 mol, 20 mg) was dissolved in 1 mL of chlorobenzene and stirred at room temperature for 24 h to obtain PC 61 BM solution, namely electron transport layer material solution.

[0103] BCP (1 × 10 -6 mol, 0.5 mg) was dissolved in 1 mL of anhydrous ethanol and stirred at room temperature for 24 h to obtain a BCP solution, i.e., a hole blocking layer material solution.

[0104] Step 3: Preparation of perovskite solar cells

[0105] The cleaned ITO conductive glass (Wuhan Jingge Solar Technology Co., Ltd., 8 Ω / m 2 , length × width = 1.5 cm × 1.3 cm, glass substrate thickness of 1 mm, conductive layer thickness of 300 nm) and dried, and treated with UV ozone cleaning machine for 20 min. This layer was used as the conductive glass substrate layer.

[0106] The hole transport layer material solution 2PACz solution was spin-coated on a clean ITO surface. The spin-coating parameters were: 3000 rpm, 30 s, heating annealing at 100 °C for 10 min, and the thickness was 20 nm. This layer served as the hole transport layer.

[0107] 50 μL of BN-2 doped Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 The perovskite precursor solution was spin-coated onto the prepared hole transport layer at the following spin-coating parameters: 1000 rpm for 5 seconds, then 4000 rpm for 20 seconds. The solution was then heated at 100°C for 30 minutes to form a perovskite light-absorbing layer. The perovskite absorber layer, prepared in a nitrogen glove box, had a thickness of 550 nm and served as the perovskite light-absorbing layer.

[0108] Spin-coat the electron transport layer material solution, PC, on the surface of the perovskite light absorbing layer. 61 BM solution, spin coating parameters are: 2000 rpm, 45 s; thickness is 20 nm, this layer serves as the electron transport layer.

[0109] The hole blocking layer material, namely BCP solution, was spin-coated on the surface of the electron transport layer. The spin-coating parameters were: 4000 rpm, 45s; heated at 70 °C for 15 min, and the thickness was 5 nm. This layer served as the hole blocking layer.

[0110] Metal silver was evaporated on the hole blocking layer using an evaporation apparatus with a thickness of 100 nm as the back electrode.

[0111] The fabricated perovskite solar cell has the following structure, from bottom to top: a conductive glass substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a back electrode. The glass substrate is 1 mm thick, the conductive layer is 300 nm thick, the hole transport layer is 20 nm thick, the perovskite light-absorbing layer is 550 nm thick, the electron transport layer is 20 nm thick, the hole blocking layer is 5 nm thick, and the back electrode is 100 nm thick.

[0112] Example 3

[0113] The conductive substrate in Example 1 was replaced with FTO conductive glass (purchased from Wuhan Jingge Solar Technology Co., Ltd., 14 Ω / m 2 , length × width = 1.5 cm × 1.3 cm, glass substrate thickness is 2 mm, conductive layer thickness is 500 nm), and the rest is the same as in Example 1.

[0114] Example 4

[0115] The back electrode in Example 1 is replaced with metal copper, and the rest is the same as Example 1.

[0116] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments using the above technical content without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A method for preparing a hexagonal boron nitride-modified perovskite heterostructure, characterized in that: An ester-modified functionalized hexagonal boron nitride solution is added to a perovskite precursor solution, mixed to prepare an improved perovskite precursor solution, which is then spin-coated on a hole transport layer of a perovskite solar cell and heated and annealed to obtain a perovskite film as a perovskite absorber layer. Wherein, the perovskite precursor is selected from any one of the following materials: Cs x FA y MA 1-x-y Pb(I z Br 1-z )3, where x is 0~1, y is 0~1, and z is 0~1; CH3NH3PbI3; MAPb x Sn 1-x I3, where x is 0 to 1; CH(NH2)2PbI3; FAPb x Sn 1-x I3, where x is 0~1; Cs x MA 1-x Pb(I y Br 1-y )3, where x is 0~1, y is 0~1; Cs x FA 1-x Pb(I y Br 1-y )3, where x is 0~1; y is 0~1; FA x MA 1-x Pb(I y Br 1-y )3, where x is 0~1; y is 0~1; CsPb(I x Br 1-x )3, where x is 0~1; CsSn(I x Br 1-x )3, where x is 0 to 1; (PEA)2(MA) n-1 Pb n I 3n+1 , where n is an integer starting from 1; The ester-modified functionalized hexagonal boron nitride is hexagonal boron nitride prepared based on an ester-assisted ball milling method.

2. The preparation method according to claim 1, wherein: in, The mass fraction of the functionalized hexagonal boron nitride in the improved perovskite precursor solution is 7%, and the solvent is at least one of the perovskite precursor solvents; The ester is selected from any one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, ethyl acetate, ethylene carbonate, propylene carbonate, trimethyl citrate, and ethylene glycol oxalate.

3. The preparation method according to claim 2, wherein: in, The specific steps of the ester-assisted ball milling method are as follows: micron-sized hexagonal boron nitride powder and ester are added to a steel grinding jar containing 8 mm diameter steel balls in a mass ratio of 1:4, maintaining the ball-to-powder mass ratio at 50:1; the ball mill speed is set to 400 rpm, and the ball milling is continued for 12 hours. After the ball milling is completed, the product is collected and repeatedly washed with deionized water and ethanol until the pH value is close to neutral; the sample is placed in a vacuum oven for drying and then dispersed in ethanol and ultrasonically treated for 1 hour to obtain a uniformly dispersed hexagonal boron nitride solution. The dispersed hexagonal boron nitride solution is then centrifuged at 2000 rpm for 30 minutes to remove agglomerates and thick layer materials. The supernatant after centrifugation is the final product.

4. The preparation method according to claim 1, wherein: in, The perovskite precursor solution is selected from Cs x FA y MA 1-x-y Pb(I z Br 1-z )3 perovskite precursor solution, the preparation method comprises the following steps: dissolving cesium iodide, methylamine bromide, lead bromide, formamidine hydroiodide, and lead iodide powder in a molar ratio of 1:1~5:0.05~5:1~30:1~30 in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide being 2~8:1, stirring at room temperature overnight to obtain the Cs x FA y MA 1-x-y Pb(I z Br 1-z )3 solution.

5. The preparation method according to claim 1, wherein: in, The perovskite precursor solution is selected from Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 The preparation method of the perovskite precursor solution comprises the following steps: dissolving cesium iodide, methylamine bromide, lead bromide, formamidine hydroiodide, and lead iodide powder in a molar ratio of 1:2:3.1:16.2:16.9 in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide, wherein the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is 2-8:1, and stirring at room temperature overnight to obtain the Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 of solution.

6. A perovskite solar cell, characterized in that: The structure from bottom to top is: a conductive substrate layer, a hole transport layer, a perovskite light absorbing layer, an electron transport layer, a hole blocking layer, and a back electrode; wherein the perovskite light absorbing layer is a functionalized hexagonal boron nitride-doped perovskite film, and the preparation method is as shown in any one of claims 1 to 5.

7. The perovskite solar cell according to claim 6, characterized in that in, The conductive substrate layer is made of a material selected from FTO conductive glass or ITO conductive glass, wherein the thickness of the substrate is 1-2 mm and the thickness of the conductive layer is 200-600 nm; The hole transport layer has a thickness of 10 to 50 nm, and the material is selected from any one of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), poly(3,4-ethylenedioxythiophene) (PEDOT:PSS), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)]amine (PTAA); The thickness of the perovskite light absorbing layer is 500-1500 nm; The thickness of the electron transport layer is 20 nm, and the material is selected from [6,6]-phenyl-C 61 -Methyl butyrate ([6,6]-Phenyl-C 61 -butyric acid methyl ester, PC 61 BM); The hole blocking layer has a thickness of 5 nm and is made of a material selected from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Bathocuproine, BCP); The thickness of the back electrode is 100 nm, and the material is selected from silver.

8. The method for preparing a perovskite solar cell according to claim 6 or 7, characterized in that: The steps include: Step (1), spin coating a hole transport layer material solution on the surface of a clean conductive substrate layer, which serves as the hole transport layer; Step (2), spin-coating the perovskite precursor solution on the hole transport layer prepared above in an inert atmosphere to form a perovskite light absorbing layer film, which serves as the perovskite light absorbing layer; Step (3), spin coating an electron transport layer material solution on the surface of the perovskite light absorbing layer, and the layer serves as the electron transport layer; Step (4), spin coating a hole blocking layer material solution on the surface of the electron transport layer, and the layer serves as a hole blocking layer; Step (5): evaporating metal on the hole blocking layer to serve as a back electrode.

9. The method for preparing a perovskite solar cell according to claim 8, wherein: in, In step (1), the conductive substrate layer is treated as follows: the conductive substrate is repeatedly ultrasonically cleaned three times with deionized water, acetone, and ethanol, and then dried to completely remove the solvent and moisture; the cleaned conductive substrate is dried and treated with ultraviolet ozone for 10 to 30 minutes, and the layer is used as the conductive substrate layer; The conditions for spin coating the hole transport layer material solution are as follows: 3000 rpm, 30 s, heating annealing at 80-130 °C for 3-20 min; In step (2), the spin coating conditions of the perovskite precursor solution are as follows: 1000 rpm, 5 s, 4000 rpm, 20 s; heating at a temperature of 80-130 °C for 5-40 min; In step (3), the spin coating conditions for the electron transport layer material solution are as follows: 2000 rpm, 45 s; In step (4), the conditions for spin coating the hole blocking layer material solution are as follows: 4000 rpm, 45 s; heating at a temperature of 60~90 °C for 5~20 min.

10. The method for preparing a perovskite solar cell according to claim 8, wherein: in, The hole transport layer material solution is prepared by dissolving the hole transport layer material in anhydrous ethanol to form a hole transport layer material solution with a concentration of 0.1 to 1 mg / mL; The preparation method of the electron transport layer material solution is as follows: dissolving the electron transport layer material in chlorobenzene to form an electron transport layer material solution with a concentration of 20 mg / mL; The hole blocking layer material solution is prepared by dissolving the hole blocking layer material in anhydrous ethanol to form a hole blocking layer material solution with a concentration of 0.5 mg / mL.

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