Electron transport layer precursor, trans-perovskite cell and preparation method

Abstract

The invention provides an electron transport layer precursor, a trans-perovskite cell and a preparation method, and the preparation method of the electron transport layer precursor comprises the following steps: dispersing tin dioxide nanoparticles in an organic solvent, adding carboxylic acid into the organic solvent to adjust the pH value to 5.5-6.5, and then carrying out ultrasonic dispersion to obtain the electron transport layer precursor. Tin dioxide nanoparticles are dispersed in an organic solvent by using carboxylic acid, the pH value is adjusted to 5.5-6.5, carboxyl in an acidic medium can be coordinated with Sn-OH groups on the surface of tin dioxide, and residual carboxylate ions (-COO-) can provide electrostatic repulsive force, so that the dispersion of tin dioxide is facilitated; meanwhile, carbon chains of carboxylic acid molecules can provide certain steric hindrance, and agglomeration of tin dioxide nanoparticles is avoided.

Description

Technical Field

[0001] This invention relates to the field of inverted perovskite solar cell technology, specifically to an electron transport layer precursor, an inverted perovskite solar cell, and a preparation method thereof. Background Technology

[0002] Invert perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field in recent years due to their advantages such as high photoelectric conversion efficiency, low cost, and ability to be stacked with silicon solar cells to break through the efficiency limit of single cells.

[0003] Currently, most inverted perovskite solar cells (PSCs) are based on fullerenes and their derivatives as electron transport materials. However, the high cost and poor mechanical properties of fullerenes limit their value in commercial applications. Furthermore, ion movement between the electron transport layer and the perovskite layer not only leads to severe defect recombination but also acts as defect sites, accelerating perovskite degradation. Replacing fullerenes with tin oxide via atomic layer deposition (ALD) can suppress perovskite ion movement and significantly improve the stability of PSCs. However, the expensive ALD equipment and lengthy deposition time increase the device's equipment and time costs, hindering its competitiveness in the commercial market.

[0004] Chinese invention patent 202410313356.4 discloses a method for preparing high-efficiency perovskite solar cells based on a carboxylate gelled electron transport layer, using carboxylate gelled tin oxide to prepare the electron transport layer. This application uses water as a solvent, but in the process of preparing inverted perovskite solar cells, water as a solvent would damage the perovskite light-absorbing layer at the bottom of the electron transport layer. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides an electron transport layer precursor, an inverse perovskite solar cell and a preparation method thereof, aiming to solve the technical problems of long preparation time and high cost of tin dioxide electron transport layer by atomic deposition.

[0006] In a first aspect, this application provides a method for preparing an electron transport layer precursor, comprising the following steps: dispersing tin dioxide nanoparticles in an organic solvent, adding carboxylic acid to adjust the pH to 5.5-6.5, and then ultrasonically dispersing to obtain the electron transport layer precursor.

[0007] In the technical solution of this application embodiment, the tin dioxide electron transport layer can suppress the migration of perovskite ions and significantly improve the stability of PSCs. However, the current liquid phase preparation method of tin dioxide uses water as a solvent. When the electron transport layer precursor is coated on the perovskite light-absorbing layer, it will destroy the structure of the perovskite light-absorbing layer. Therefore, using water as a solvent is not suitable for inverted perovskite solar cells.

[0008] However, in organic solvents such as isopropanol, tin dioxide nanoparticles tend to aggregate, leading to poor film formation. Therefore, in this invention, carboxylic acid is used as a dispersant, and the pH is adjusted to 5.5-6.5. In acidic media, the carboxyl groups can coordinate with the Sn-OH groups on the surface of tin dioxide, and the remaining carboxylate ions (-COO) - The presence of tin dioxide nanoparticles provides electrostatic repulsion, which is beneficial for tin dioxide dispersion. Simultaneously, the carbon chains of carboxylic acid molecules provide steric hindrance, preventing the aggregation of tin dioxide nanoparticles. A pH of 5.5–6.5 increases the ionization degree of carboxylic acid particles, maximizing steric hindrance and achieving a uniform distribution of nanoparticles. This results in a uniformly dispersed tin dioxide nanoparticle dispersion, which is then used as a precursor for the electron transport layer of an inverted perovskite solar cell. Spin-coating this dispersion onto the surface of a perovskite thin film yields a low-cost, high-efficiency, and stable perovskite solar cell, enhancing its commercial competitiveness.

[0009] Furthermore, in some embodiments, the diameter of the tin dioxide nanoparticles is 20-50 nm.

[0010] Furthermore, in some embodiments, the carboxylic acid includes at least one of acetic acid, propionic acid, and citric acid.

[0011] Furthermore, in some embodiments, the organic solvent includes at least one selected from isopropanol, toluene, and chlorobenzene. Preferably, the organic solvent is isopropanol.

[0012] In the technical solutions of this application embodiment, solvents such as isopropanol are selected to avoid damage to the perovskite layer.

[0013] Furthermore, in some embodiments, the mass ratio of tin dioxide nanoparticles to carboxylic acid is 20:(0.3~2.4).

[0014] In the technical solutions of this application embodiment, the mass ratio of tin dioxide nanoparticles to carboxylic acid includes, but is not limited to, the range described above. Within this range, the tin dioxide nanoparticles achieve the optimal dispersion effect. If the carboxylic acid mass ratio is too low, it is difficult to achieve effective dispersion of the tin dioxide nanoparticles; if the carboxylic acid mass ratio is too high, a large amount of carboxylic acid without electron transport capability will remain in the final electron layer, affecting the final performance of the device.

[0015] Furthermore, in some embodiments, the concentration of tin dioxide nanoparticles in the electron transport layer precursor is 1~6 mg / mL.

[0016] Secondly, this application provides an electron transport layer precursor, which is prepared by the above-described method.

[0017] Thirdly, this application provides an inverted perovskite solar cell, comprising a transparent substrate, a conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode stacked sequentially, wherein the electron transport layer is formed from the aforementioned electron transport layer precursor.

[0018] Fourthly, this application provides a method for preparing an inverted perovskite solar cell, comprising the following steps: S1. Hole transport layer and perovskite light-absorbing layer are coated sequentially on a transparent substrate; S2. Spin-coat the electron transport layer precursor onto the perovskite light-absorbing layer, and anneal it to obtain the electron transport layer. S3. A back electrode is deposited on the electron transport layer to obtain an inverse perovskite solar cell.

[0019] Furthermore, in some embodiments, the spin coating speed is 500~4000 rpm and the spin coating time is 20~60s.

[0020] Furthermore, in some embodiments, the annealing temperature is 70~100°C and the annealing time is 5~20 min.

[0021] The advantages of this application, which differ from existing technical solutions, include: 1. This invention utilizes carboxylic acid to disperse tin dioxide nanoparticles in an organic solvent and adjusts the pH to 5.5-6.5. In the acidic medium, the carboxyl groups can coordinate with the Sn-OH groups on the surface of tin dioxide, and the remaining carboxylate ions (-COO) - The presence of carboxylic acid molecules provides electrostatic repulsion, which is beneficial for the dispersion of tin dioxide. Simultaneously, the carbon chains of the carboxylic acid molecules provide steric hindrance, preventing the aggregation of tin dioxide nanoparticles. This results in a uniformly dispersed tin dioxide nanoparticle dispersion, which is then used as a precursor for the electron transport layer of an inverted perovskite solar cell. By spin-coating this dispersion onto the surface of a perovskite thin film, a low-cost, high-efficiency, and stable perovskite solar cell can be obtained, enhancing the commercial competitiveness of perovskite solar cells.

[0022] 2. This invention provides a liquid-phase preparation method for tin oxide electron layers that can be used in inverted perovskite solar cells. This method is simple to prepare and low in cost. It not only solves the stability problem of conventional fullerene electron transport layers, but also significantly reduces the fabrication cost of devices, and has broad market application potential.

[0023] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0025] Figure 1 This is a schematic diagram of the inverted perovskite solar cell structure provided in Embodiment 1 of this application.

[0026] Figure 2 This is a statistical efficiency comparison chart between Example 1 and Comparative Example 1 of this application.

[0027] Figure 3 The images show the JV curves before and after aging for Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0028] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0030] Currently, most inverted perovskite solar cells (PSCs) are based on fullerenes and their derivatives as electron transport materials. However, the high cost and poor mechanical properties of fullerenes limit their value in commercial applications. Furthermore, ion movement between the electron transport layer and the perovskite layer not only leads to severe defect recombination but also acts as defect sites, accelerating perovskite degradation. Replacing fullerenes with tin oxide via atomic layer deposition (ALD) can suppress perovskite ion movement and significantly improve the stability of PSCs. However, the expensive ALD equipment and lengthy deposition time increase the device's equipment and time costs, hindering its competitiveness in the commercial market.

[0031] To address the technical challenges of long preparation time and high cost in atomic deposition of tin dioxide electron transport layers, this application provides an electron transport layer precursor, an inverse perovskite solar cell, and a preparation method. In this invention, tin dioxide nanoparticles are dispersed in an organic solvent using carboxylic acid, and the pH is adjusted to 5.5-6.5. In the acidic medium, the carboxyl groups can coordinate with the Sn-OH groups on the surface of tin dioxide, and the remaining carboxylate ions (-COO)... -The carboxylic acid molecules can provide electrostatic repulsion, which is beneficial for the dispersion of tin dioxide. At the same time, the carbon chains of the carboxylic acid molecules can provide a certain degree of steric hindrance, preventing the aggregation of tin dioxide nanoparticles.

[0032] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0033] I. Preparation Method Example 1 A type of inverted perovskite solar cell, such as Figure 1 As shown, the structure includes a transparent substrate, a conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode, which are sequentially stacked. The fabrication method of the inverted perovskite solar cell includes the following steps: S1: Fabrication of patterned transparent conductive substrate: S1-1: A glass substrate with a fluorine-doped tin oxide conductive layer was etched for 15 s using zinc powder and 6 mol / L hydrochloric acid. It was then ultrasonically cleaned with deionized water, ethanol, acetone, and isopropanol, respectively, for 15 min each. Subsequently, it was dried in dry air with nitrogen gas and subjected to ultraviolet ozone treatment; the ultraviolet light wavelength was 185 nm, the power was 2250 W, and the irradiation time was 20 min, resulting in a clean, patterned transparent conductive substrate with a fluorine-doped tin oxide conductive layer.

[0034] S2: Fabrication of the hole transport layer: S2-1: Dissolve 30 mg of nickel acetylacetone in 20 mL of an acetonitrile / ethanol mixture with a volume ratio of 95:5 to form NiO with a concentration of 1.5 mg / mL. x Precursor solution.

[0035] S2-2: Transfer the conductive glass substrate to 500 o On a C-type titanium plate heating stage, a nickel oxide precursor solution was uniformly sprayed onto the FTO glass using a high-pressure nitrogen spray gun within 10 minutes, followed by continuous 500°C treatment on the substrate. o Heating at C for 30 minutes forms a dense nickel oxide layer with a thickness of approximately 15-20 nm, followed by natural cooling to 120°C. o C.

[0036] S2-3: Prepare a SAM solution by mixing 1.0 mg of [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate (Me-4PACz) and other SAMs with 1 mL of ethanol.

[0037] S2-4: The SAM solution was spin-coated onto a surface-hydroxylated nickel oxide substrate at a speed of 4000 rpm for 30 s, and then annealed at 100 ℃ for 10 min to obtain a nickel oxide / SAMs bilayer hole transport layer.

[0038] S3: Preparation of the perovskite light-absorbing layer: S3-1: A perovskite solution with a total concentration of 1.4 mol / L is prepared using a mixture of dimethylformamide and dimethyl sulfoxide as solvent (volume ratio = 4:1) and cesium iodide, formamidine iodide, lead iodide, and methylamine chloride as solutes (molar ratio = 0.05:0.95:1.05:0.12).

[0039] S3-2: The perovskite solution was spin-coated onto the hole transport layer at 1000 rpm for 12 s. The spin-coating time was then increased to 5000 rpm for 38 s. During the 38th-40th s of the total spin-coating time, 150 μL of chlorobenzene was rapidly added dropwise onto the precursor solution film to obtain an intermediate phase film. The perovskite intermediate phase was then annealed at 100 °C for 20 min to obtain a perovskite light-absorbing layer with a thickness of approximately 600 nm.

[0040] S4: Fabrication of the electron transport layer: S4-1: Add 20 mg of tin dioxide nanoparticles and 0.6 mg of acetic acid to 5 mL of isopropanol, and ultrasonically disperse for 45 min to obtain a uniformly dispersed tin dioxide nanoparticle dispersion. S4-2: Tin dioxide nanoparticle dispersion was spin-coated onto a surface-hydroxylated nickel oxide substrate at a speed of 2000 rpm for 30 s, and then annealed at 100 ℃ for 10 min to obtain an electron transport layer.

[0041] S5: Fabrication of perovskite solar cells: A vacuum evaporation apparatus was used, with a hole area of ​​0.09 cm². 2 Using a mask template, a 90 nm copper electrode is deposited on the hole transport layer at a rate of 1 Å / s to obtain a perovskite solar cell.

[0042] Example 2 A method for preparing an inverted perovskite solar cell differs from Example 1 in that the amount of acetic acid added in step S4-1 is 0.3 mg / L, while the other steps are the same as in Example 1.

[0043] Example 3 A method for preparing an inverted perovskite solar cell differs from Example 1 in that the amount of acetic acid added in step S4-1 is 0.9 mg / L, while the other steps are the same as in Example 1.

[0044] Example 4 A method for preparing an inverted perovskite solar cell differs from Example 1 in that the amount of acetic acid added in step S4-1 is 1.2 mg / L, while the other steps are the same as in Example 1.

[0045] Example 5 A method for preparing an inverted perovskite solar cell differs from Example 1 in that acetic acid is replaced with propionic acid in step S4-1, and the amount added is 0.3 mg / L. All other steps are the same as in Example 1.

[0046] Example 6 A method for preparing an inverted perovskite solar cell differs from Example 1 in that acetic acid is replaced with propionic acid in step S4-1, and the amount added is 0.6 mg / L. All other steps are the same as in Example 1.

[0047] Example 7 A method for preparing an inverted perovskite solar cell differs from Example 1 in that acetic acid is replaced with propionic acid in step S4-1, and the amount added is 1.2 mg / L. All other steps are the same as in Example 1.

[0048] Example 8 A method for preparing an inverted perovskite solar cell differs from Example 1 in that acetic acid is replaced with citric acid in step S4-1, and the amount added is 0.6 mg / L. All other steps are the same as in Example 1.

[0049] Example 9 A method for preparing an inverted perovskite solar cell differs from Example 1 in that acetic acid is replaced with citric acid in step S4-1, and the amount added is 1.2 mg / L. All other steps are the same as in Example 1.

[0050] Example 10 A method for preparing an inverted perovskite solar cell differs from Example 1 in that acetic acid is replaced with citric acid in step S4-1, and the amount added is 2.4 mg / L. All other steps are the same as in Example 1.

[0051] Example 11 A method for preparing an inverted perovskite solar cell differs from Example 1 in that the ultrasonic dispersion time in step S4-1 is 15 min, while the other steps are the same as in Example 1.

[0052] Example 12 A method for preparing an inverted perovskite solar cell differs from Example 1 in that the ultrasonic dispersion time in step S4-1 is 30 min, while the other steps are the same as in Example 1.

[0053] Example 13 A method for preparing an inverted perovskite solar cell differs from Example 1 in that the ultrasonic dispersion time in step S4-1 is 60 min, while the other steps are the same as in Example 1.

[0054] Comparative Example 1 A method for preparing an inverted perovskite solar cell differs from Example 1 in that propionic acid is not added in step S4-1.

[0055] Comparative Example 2 A method for preparing an inverted perovskite solar cell, which differs from Comparative Example 1 in that the ultrasonic dispersion time in step S4-1 is 15 min.

[0056] Comparative Example 3 A method for preparing an inverted perovskite solar cell, which differs from Comparative Example 1 in that the ultrasonic dispersion time in step S4-1 is 30 min.

[0057] Comparative Example 4 A method for preparing an inverted perovskite solar cell differs from Comparative Example 1 in that the ultrasonic dispersion time in step S4-1 is 60 min.

[0058] II. Testing Methods At AM1.5G (100mW cm -2 Under simulated solar conditions at Wacom Denso Co., Ltd. in Japan, the current density-voltage (JV) curve of the perovskite solar cell was measured using a Keithley 2400 digital source meter to obtain the V value of the perovskite solar cell. OC J SC Information such as FF and PCE is displayed. Measurements are performed using either a forward (-0.2 to 1.3 V) scan or a reverse (1.3 to -0.2 V) scan. The delay time and step voltage are set to 20 ms and 20 mV, respectively.

[0059] III. Analysis of Test Results for Each Embodiment and Comparative Example (1) The performance parameters of the perovskite solar cells obtained in each embodiment and comparative example were tested, and the test results are shown in Table 1 below.

[0060] Table 1. Aperture area 0.09 cm² 2 Perovskite solar cell performance parameters

[0061] The power conversion efficiency (PCE) of perovskite solar cells reflects the quality of the electron transport layer fabricated on the perovskite substrate. Table 1 shows that in Comparative Examples 1-4, the lack of carboxylic acid resulted in poor uniformity of the electron layer film due to tin oxide agglomeration in solution, leading to severe carrier recombination and significantly reduced Voc and FF. In contrast, Examples 1-13 exhibited higher Voc and FF due to the uniform distribution of the electron layer, reducing carrier recombination and resulting in a significant improvement in device efficiency.

[0062] (2) Fifty perovskite solar cells prepared according to Example 1 and Comparative Example 1 were taken respectively for conversion efficiency testing. The test results are shown in the figure. Figure 2 The conversion efficiencies of the perovskite solar cells prepared in Example 1 and Comparative Example 1 both exhibit a normal distribution, indicating that the data can reflect the true distribution of the device. The comparison shows that the efficiency distribution of Comparative Example 1 is more discrete than that of Example 1, indicating that the efficiency reproducibility of the inverted perovskite solar cells prepared based on the present invention is better, and it is easier to reproduce high-efficiency inverted perovskite solar cells.

[0063] (3) The inverted perovskite solar cells prepared in Example 1 and Comparative Example 1 were subjected to an aging test based on the ISOS-L-3 aging protocol, operating continuously for 1200 hours. This test was conducted on a solar cell light resistance testing system (Bunkoukeiki, Japan) under AM1.5G sunlight (100 mW cm⁻¹). -2 ).

[0064] Figure 3 The JV curves of the inverted perovskite solar cells prepared in Example 1 and Comparative Example 1 before and after aging are shown. It can be seen that after aging, the Voc, Jsc and FF of Comparative Example 1 decreased significantly, and the device efficiency eventually decreased to 66% of the original efficiency. However, due to the more stable electronic layer structure, the photovoltaic parameters of Example 1 decreased significantly, and the device maintained more than 90% of the initial efficiency. This shows that the inverted perovskite solar cell based on liquid-phase dispersed tin oxide electronic layer prepared in this invention has stronger stability.

[0065] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing an electron transport layer precursor, characterized in that, The process includes the following steps: dispersing tin dioxide nanoparticles in an organic solvent, adding carboxylic acid to adjust the pH to 5.5-6.5, and then ultrasonically dispersing to obtain an electron transport layer precursor.

2. The method for preparing the electron transport layer precursor according to claim 1, characterized in that, The diameter of the tin dioxide nanoparticles is 20~50nm.

3. The method for preparing the electron transport layer precursor according to claim 1, characterized in that, The carboxylic acid includes at least one selected from acetic acid, propionic acid, and citric acid; and / or The organic solvent includes at least one of isopropanol, toluene, and chlorobenzene.

4. The method for preparing the electron transport layer precursor according to claim 1, characterized in that, The mass ratio of tin dioxide nanoparticles to carboxylic acid is 20:(0.3~2.4); and / or The concentration of tin dioxide nanoparticles in the electron transport layer precursor is 1~6 mg / mL.

5. The method for preparing the electron transport layer precursor according to claim 1, characterized in that, The ultrasonic dispersion time is 15~60 min.

6. An electron transport layer precursor, characterized in that, It is prepared by any one of claims 1 to 5.

7. A trans-perovskite solar cell, characterized in that, It includes a transparent substrate, a conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a back electrode, which are stacked sequentially. The electron transport layer is obtained from the electron transport layer precursor described in claim 6.

8. A method for preparing a trans-perovskite solar cell as described in claim 7, comprising the following steps: S1. Hole transport layer and perovskite light-absorbing layer are coated sequentially on a transparent substrate; S2. Spin-coat the electron transport layer precursor onto the perovskite light-absorbing layer, and anneal it to obtain the electron transport layer. S3. A back electrode is deposited on the electron transport layer to obtain an inverse perovskite solar cell.

9. The method for preparing an inverse perovskite solar cell according to claim 8, characterized in that, In step S2, the spin coating speed is 500~4000 rpm and the spin coating time is 20~60s.

10. The method for preparing an inverse perovskite solar cell according to claim 8, characterized in that, The annealing temperature is 70~100℃, and the annealing time is 5~20min.

Images