Voltage-controllable perovskite photovoltaic cell and preparation method thereof

Abstract

The application discloses a perovskite photovoltaic cell with controllable voltage and a preparation method thereof. The preparation method comprises the following steps: determining the required number of sub-cells according to a target voltage, dividing a conductive substrate into multiple independent areas, and widening the preset width of the last sub-cell in each independent area; sequentially preparing a perovskite functional layer and a metal electrode layer on the surface of the conductive substrate, and performing P1, P2 and P3 scribing; performing P4 scribing on the surface of the last sub-cell in each independent area to penetrate the metal electrode layer, so that the widened area becomes a strip-shaped anode of an adjacent independent area; and conducting treatment on the surface of the strip-shaped anode to obtain a perovskite photovoltaic cell comprising multiple parallel sub-cell units. The application can reduce the voltage of full series connection to a single area voltage value under the premise that the light-receiving surface is consistent with the appearance of a conventional perovskite cell, and realizes voltage regulation of a perovskite large voltage to a target voltage.

Description

Technical Field

[0001] This invention belongs to the field of perovskite photovoltaic cell technology, specifically relating to a voltage-controllable perovskite photovoltaic cell and its preparation method. Background Technology

[0002] Perovskite solar cells are a new type of photovoltaic cell that relies on perovskite structural materials for photoelectric conversion, and belong to the third generation of solar cells.

[0003] Existing perovskite photovoltaic cells with multiple sub-cells connected in series typically employ a structure of horizontally connected sub-cells of equal width and vertical leads. This results in a fixed cell voltage that cannot be flexibly adjusted. To regulate voltage while maintaining a consistent appearance of the perovskite photovoltaic cells, it is usually necessary to directly split the series structure to reduce voltage. However, this method is prone to sub-cell current mismatch, and the positive electrode, acting as a dead zone, occupies part of the sub-cell width after splitting, further reducing the current of that sub-cell and lowering the overall output current of the cell. Simultaneously, the insufficient conductivity of the positive electrode after splitting also limits the improvement of cell efficiency, failing to simultaneously meet the dual requirements of controllable voltage and high photoelectric efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a voltage-controllable perovskite photovoltaic cell and its preparation method. Under the premise that the appearance of the light-receiving surface is consistent with that of conventional perovskite cells, the voltage of the entire series can be reduced to the voltage value of a single region, thereby achieving voltage regulation from the high voltage of the perovskite cell to the target voltage.

[0005] This invention provides the following technical solution: In a first aspect, a method for preparing a voltage-controllable perovskite photovoltaic cell is provided, comprising the following steps: The required number of sub-cells is determined based on the target voltage. The conductive substrate is divided into multiple independent regions based on the required number of sub-cells and the preset width of the sub-cells. The preset width of the last sub-cell in each independent region is widened. According to the preset width of each sub-cell, P1 lines are drawn on the surface of the conductive substrate to divide the preset sub-cell area into each independent region. A perovskite functional layer is prepared on a conductive substrate with P1 lines drawn, and P2 lines are drawn on the surface of the perovskite functional layer to separate the perovskite functional layers of each sub-cell. A metal electrode layer is deposited on the surface of the perovskite functional layer after P2 scribing, and P3 scribing is performed to separate the metal electrode layers of each sub-cell. A P4 line is drawn through the metal electrode layer on the surface of the last sub-cell in each independent region to widen the area and make it a strip-shaped positive electrode of the adjacent independent region. The surface of the strip-shaped positive electrode is made conductive, and then the current-carrying terminals of each independent region are electrically connected by lateral positive electrode leads and lateral negative electrode leads respectively located on both sides of each sub-cell, to obtain a perovskite photovoltaic cell containing multiple parallel sub-cell units.

[0006] Furthermore, the preset width of the last sub-cell in each independent region is 10% to 15% wider than the preset width of the other sub-cells in that independent region.

[0007] Furthermore, the conductive substrate is FTO conductive glass or ITO conductive glass; And / or, the metal electrode layer is a gold electrode or a silver electrode.

[0008] Furthermore, the method for preparing the perovskite functional layer includes the following steps: An electron transport layer is formed on a conductive substrate with P1 scribing using one of magnetron sputtering, liquid phase deposition or slot coating. A perovskite layer is formed on the surface of the electron transport layer using spin coating or slot coating methods; A hole transport layer is formed on the surface of the perovskite layer using spin coating or slot coating methods, thus obtaining the perovskite functional layer.

[0009] Furthermore, the electron transport layer is a SnO2 wire thin film layer or a TiO2 wire thin film layer; And / or, the perovskite layer is a formamidinium lead iodide perovskite layer; And / or, the hole transport layer is a Spiro hole transport layer.

[0010] Furthermore, the P4 scribing is performed in situ using ultraviolet laser cutting, and the width of the P4 scribing is 40~50μm.

[0011] Furthermore, the conductivity treatment includes: sequentially depositing a layer of silver nanowires and a layer of reduced graphene oxide on the surface of the strip-shaped positive electrode.

[0012] Furthermore, the conductivity treatment includes: electroplating a silver layer on the surface of the strip-shaped positive electrode, and then performing alloying sintering to form a copper-silver solid solution alloy layer.

[0013] Furthermore, the conductivity treatment includes printing a carbon nanotube-doped silver conductive paste on the surface of the strip-shaped positive electrode.

[0014] In a second aspect, a voltage-controllable perovskite photovoltaic cell is provided, which is prepared using the method described in any one of the first aspects.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention determines the required number of sub-cells based on the target voltage, and then divides the conductive substrate into multiple independent regions. The preset width of the last sub-cell in each independent region is widened. After the subsequent P3 scribing is completed, a P4 scribing is made on the surface of the last sub-cell in each independent region, penetrating the metal electrode layer, so that the widened area becomes the strip-shaped positive electrode of the adjacent independent region. On the one hand, it can reduce the voltage of the entire series to the voltage value of a single region under the premise that the light-receiving surface is consistent with the appearance of conventional perovskite cells, realize the voltage regulation from the high voltage of perovskite to the target voltage, and adapt to photovoltaic application scenarios with different voltage requirements. On the other hand, it avoids the current mismatch problem caused by the dead zone generated by the existing splitting method, and the photoelectric conversion efficiency of the cell is almost unaffected. (2) By performing conductive treatment on the surface of the strip-shaped positive electrode, the present invention can significantly improve the electrode conductivity, thereby further ensuring the output efficiency and stability of the battery; (3) The present invention uses lateral positive and lateral negative leads respectively located on both sides of each sub-cell to electrically connect the current terminals of each independent region, thereby obtaining a perovskite photovoltaic cell containing multiple parallel sub-cell units. On the one hand, the total voltage is regulated, and the parallel characteristics are used to ensure the consistency of the current of each sub-cell unit. On the other hand, the vertical lead design of the existing perovskite cell is abandoned, and lateral leads arranged along the edges of both sides of the cell are used to connect the current terminals of each independent region. This does not occupy the light-receiving area, and the lead path is shortened by more than 50%, reducing the resistance loss of the lead. Attached Figure Description

[0016] Figure 1 This is a front view of a perovskite photovoltaic cell in an embodiment of the present invention; Figure 2 This is a cross-sectional view of a perovskite photovoltaic cell in an embodiment of the present invention; Figure 3 This is a partial cross-sectional view of the perovskite photovoltaic cell in an embodiment of the present invention; Figure 4 This is a front view of another perovskite photovoltaic cell in an embodiment of the present invention; Figure 5 This is a cross-sectional view of another perovskite photovoltaic cell in an embodiment of the present invention.

[0017] The markings in the diagram are as follows: 1. Sub-cell; 101. Last sub-cell in an independent region; 2. Strip-shaped positive electrode; 3. P4 line; 4. Lateral positive electrode lead; 5. Lateral negative electrode lead; 6. Sub-cell unit; 7. Conductive substrate; 8. P1 line; 9. Perovskite functional layer; 10. P2 line; 11. Metal electrode layer; 12. P3 line. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] It should be noted that, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] Example 1

[0021] like Figures 1-3 As shown, this embodiment provides a method for fabricating a voltage-controllable perovskite photovoltaic cell, the steps of which are as follows: Step 1: Partitioning.

[0022] The required number of sub-cells is determined based on the target voltage. The conductive substrate is divided into multiple independent regions based on the required number of sub-cells and the preset width of the sub-cells. The preset width of the last sub-cell in each independent region is widened.

[0023] In this embodiment, the conductive substrate is divided into 3 independent regions, each containing 5 sub-cells designed in series. The preset width of the first 4 sub-cells in each independent region (based on the width of the perovskite layer) is 5 mm, and the preset width of the last sub-cell (based on the width of the perovskite layer) is 5.5 mm (1.1 times the conventional width).

[0024] Step 2: Base cleaning.

[0025] A 100mm×100mm ITO conductive glass was used as the conductive substrate 7. It was ultrasonically cleaned with acetone, ethanol and deionized water for 15 minutes in sequence, dried with nitrogen, and then treated with ultraviolet ozone for 20 minutes to improve the surface hydrophilicity.

[0026] Step 3: Draw a line on P1.

[0027] Based on the preset width of each sub-cell, a laser etching process (wavelength 532nm, energy density 0.5J / cm²) is used to scribble line 8 on the cleaned conductive substrate 7, with a line width of 45μm, to divide the preset sub-cell area into each independent region.

[0028] Step 4: Fabrication of the electron transport layer.

[0029] Titanium dioxide slurry was mixed with ethanol at a mass ratio of 1:5 and sonicated for 30 minutes to obtain a titanium dioxide precursor solution. The conductive substrate with P1 markings was removed, dried with nitrogen, and then subjected to UV-ozone treatment for 20 minutes to enhance surface hydrophilicity and adhesion. Subsequently, the titanium dioxide precursor solution was filtered and coated using a slit-plate method to form a titanium dioxide liquid film. The liquid film was then dried using an air knife and annealed at 100°C for 30 minutes on a hot plate to obtain a titanium dioxide film serving as an electron transport layer.

[0030] Step 5: Preparation of the perovskite layer.

[0031] Preparation of precursor mixed solution: Lead iodide (PbI2), methylamine iodine (MAI) and dimethyl sulfoxide (DMSO) are mixed in 1:1:1 molar ratio into 1 mL of N,N-dimethylformamide (DMF) and stirred evenly to obtain a precursor solution with a solid content of 78%.

[0032] Take out the conductive substrate with the electron transport layer, filter the above precursor solution, apply the perovskite wet film by slit coating, dry it with an air knife, and then transfer it to a hot oven and heat it at 120°C for 30 minutes to further anneal and remove residual solvent, thus obtaining the perovskite layer.

[0033] Step 6: Preparation of the hole transport layer.

[0034] Preparation of the hole transport material solution: 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-MeOTAD) was added to chlorobenzene, followed by the addition of 4-tert-butylpyridine and a lithium salt solution to obtain the Spiro solution. The lithium salt was lithium bis(trifluoromethane)sulfonylimide. The concentration of Spiro-MeOTAD in chlorobenzene was 72.3 mg / mL, the concentration of 4-tert-butylpyridine in chlorobenzene was 30 μL / mL, and the concentration of lithium salt in chlorobenzene was 17.5 μL / mL. The Spiro solution was slit-coated onto a perovskite layer and dried with an air knife to obtain the Spiro hole transport layer.

[0035] Step 7: Draw a line on P2.

[0036] The aforementioned electron transport layer, perovskite layer, and hole transport layer constitute the perovskite functional layer 9. A P2 line 10 with a line width of 30 μm is etched on the surface of the perovskite functional layer 9 using a laser etching process (wavelength 532 nm, energy density 0.5 J / cm²) to separate the perovskite functional layers of each sub-cell.

[0037] Step 8: Preparation of the metal electrode layer.

[0038] A 100 nm thick Ag metal electrode, i.e., metal electrode layer 11, was deposited by thermal evaporation at a rate of 0.1 nm / s and a vacuum degree ≤ 5 × 10⁻⁻⁻⁶. 4 Pa. In this embodiment, a positive electrode is designed to be connected to the first sub-cell in the first independent region.

[0039] Step 9: Draw a line on P3.

[0040] Laser etching (wavelength 532nm, energy density 0.5J / cm²) was used to scribing lines 12 (P3) with a line width of 50μm on the surface of the metal electrode 11 to separate the metal electrode layers of each sub-cell.

[0041] Step 10: Draw a line on page 4.

[0042] A 355nm ultraviolet laser is used to perform in-situ cutting on the surface of the last sub-cell 101 in each independent region. The cutting depth penetrates the metal electrode layer 11, and the line width is 45μm. This completes the P4 scribing 3, achieving electrical isolation between regions. The widened area after cutting becomes the strip-shaped positive electrode 2 of the adjacent independent region.

[0043] Step 11: Conductivity treatment.

[0044] A layer of silver nanowires (diameter 20~50nm, length 5~10μm) and a layer of reduced graphene oxide are sequentially deposited on the surface of the strip-shaped positive electrode 2, and the total thickness of the composite coating is controlled at 100~200nm.

[0045] Step 12, horizontal lead wire.

[0046] Ag lateral positive electrode leads 4 and Ag lateral negative electrode leads 5 are prepared on both sides of each sub-cell 1 by screen printing, and the current-carrying terminals of each independent region are electrically connected to obtain a perovskite photovoltaic cell containing multiple parallel sub-cell units 6.

[0047] Step 13, encapsulation.

[0048] Flexible encapsulation was achieved using POE film and four-sided sealant. The cut battery components were bonded to a transparent flexible barrier film, with the adhesive layer thickness controlled between 300 and 400 μm. Encapsulation was completed by vacuuming for 600 seconds and laminating for 600 seconds at 60 kPa pressure and 120°C. After encapsulation, edge cleaning and lead wire treatment were performed for easy testing.

[0049] Example 2

[0050] The difference between this embodiment and embodiment 1 is that: in step 1, the preset width of the last sub-battery in the independent area is 5.65mm (1.13 times the conventional width); in step 11, the conductive treatment method is: electroplating a silver layer on the surface of the strip positive electrode with a silver layer thickness of 50nm, and then alloying and sintering at 150℃ to form a copper-silver solid solution alloy layer.

[0051] Example 3

[0052] The difference between this embodiment and Embodiment 1 is that: in step 1, the preset width of the last sub-cell in the independent area is 5.75 mm (1.15 times the conventional width); the conductivity treatment method in step 11 is: printing silver conductive paste doped with multi-walled carbon nanotubes on the surface of the strip positive electrode, the diameter of the multi-walled carbon nanotubes is 10~20 nm, the aspect ratio is 500:1, and the doping amount of multi-walled carbon nanotubes is 2% of the paste.

[0053] Comparative Example 1 The difference between this comparative example and Example 1 is that the conductive treatment in step 11 is not performed.

[0054] Comparative Example 2 The difference between this comparative example and Example 2 is that the conductive treatment in step 11 is not performed.

[0055] Comparative Example 3 The difference between this comparative example and Example 3 is that the conductive treatment in step 11 is not performed.

[0056] Comparative Example 4 This comparative example uses existing technology to prepare perovskite photovoltaic cells. The difference from Example 1 is that: the partitioning in step 1, the P4 marking in step 10, and the conductivity treatment in step 11 are not performed; 15 sub-cells are connected in series, and no horizontal leads are used in step 12, but a traditional vertical lead structure is used.

[0057] Performance testing The output voltage, photoelectric conversion efficiency, current uniformity, and stability of Examples 1-3 and Comparative Example 4 were tested, and the results are shown in Table 1 below. The positive electrode conductivity and contact resistance of Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 2 below.

[0058] Output voltage test conditions: AM1.5G standard sunlight (100mW / cm²). Photovoltaic conversion efficiency test conditions: AM1.5G standard sunlight; Current uniformity test conditions: Infrared thermal imaging + current distribution test to obtain the current deviation in each region; Stability test conditions: 85℃ / 85% RH damp heat aging for 1000h, test efficiency retention rate; Positive electrode conductivity testing conditions: four-probe method; Contact resistance test conditions: Transmission line model method (TLM), T / CPIA 0051-2023.

[0059] Table 1. Comparison of electrical performance test results between Examples 1-3 and Comparative Example 4

[0060] As shown in Table 1, the comparison of electrical performance between Examples 1-3 and Comparative Example 4 shows that after special P4 scribing treatment, the voltage is accurately controlled and reduced from 15V to the target value of 5V; and the photoelectric conversion efficiency does not decrease significantly, with an efficiency retention rate of over 90%.

[0061] Table 2 Comparison of electrical performance test results between Examples 1-3 and Comparative Examples 1-3

[0062] As shown in Table 2, comparing Comparative Example 1 and Example 1, after conductivity treatment, the conductivity of the positive electrode increased from 6.3 × 10⁻⁶. 7 S / m increased to 1.2×10 8 S / m, conductivity increased by 87.3%, and sheet resistance increased from 15Ω / m 2 Reduced to 5Ω / m 2 The surface resistivity decreased by 66.7%; comparing Comparative Example 2 and Example 2, after conductivity treatment, the conductivity of the positive electrode decreased from 5.9 × 10⁻⁶. 7 S / m increased to 9.5×10 7 The conductivity increased by 61.0% (S / m), and the contact resistance decreased from 20 mΩ to 8 mΩ, a reduction of 60%. Comparing Comparative Example 3 with Example 3, after conductivity treatment, the conductivity of the positive electrode increased from 5.8 × 10⁻⁶. 7 S / m increased to 1.05×10 8 S / m, conductivity increased by 81.0%, contact resistance from 12Ω / m 2 Reduced to 4Ω / m 2 The resistance decreased by 66.7%. This indicates that by performing a conductive treatment on the surface of the strip-shaped positive electrode, the present invention can significantly improve the electrode conductivity, further ensuring the output efficiency and stability of the battery.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. For example, the specific steps of steps 2 to 9 in Example 1 can be achieved using other existing methods for preparing perovskite photovoltaic cells. The number of sub-cells is not limited to 15; see [link to relevant documentation]. Figure 4 and Figure 5In some other embodiments, the number of sub-cells can be more.

[0064] It should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing a voltage-controllable perovskite photovoltaic cell, characterized in that, Includes the following steps: The required number of sub-cells is determined based on the target voltage. The conductive substrate is divided into multiple independent regions based on the required number of sub-cells and the preset width of the sub-cells. The preset width of the last sub-cell in each independent region is widened. According to the preset width of each sub-cell, P1 lines are drawn on the surface of the conductive substrate to divide the preset sub-cell area into each independent region. A perovskite functional layer is prepared on a conductive substrate with P1 lines drawn, and P2 lines are drawn on the surface of the perovskite functional layer to separate the perovskite functional layers of each sub-cell. A metal electrode layer is deposited on the surface of the perovskite functional layer after P2 scribing, and P3 scribing is performed to separate the metal electrode layers of each sub-cell. A P4 line is drawn through the metal electrode layer on the surface of the last sub-cell in each independent region to widen the area and make it a strip-shaped positive electrode of the adjacent independent region. The surface of the strip-shaped positive electrode is made conductive, and then the current-carrying terminals of each independent region are electrically connected by lateral positive electrode leads and lateral negative electrode leads respectively located on both sides of each sub-cell, to obtain a perovskite photovoltaic cell containing multiple parallel sub-cell units.

2. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The preset width of the last sub-cell in each independent region is 10% to 15% wider than the preset width of the other sub-cells in that independent region.

3. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The conductive substrate is FTO conductive glass or ITO conductive glass; And / or, the metal electrode layer is a gold electrode or a silver electrode.

4. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The method for preparing the perovskite functional layer includes the following steps: An electron transport layer is formed on a conductive substrate with P1 scribing using one of magnetron sputtering, liquid phase deposition or slot coating. A perovskite layer is formed on the surface of the electron transport layer using spin coating or slot coating methods; A hole transport layer is formed on the surface of the perovskite layer using spin coating or slot coating methods, thus obtaining the perovskite functional layer.

5. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 4, characterized in that, The electron transport layer is a SnO2 wire thin film layer or a TiO2 wire thin film layer; And / or, the perovskite layer is a formamidinium lead iodide perovskite layer; And / or, the hole transport layer is a Spiro hole transport layer.

6. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The P4 scribing is performed using an ultraviolet laser for in-situ laser cutting, and the width of the P4 scribing is 40~50μm.

7. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The conductivity treatment includes: sequentially depositing a layer of silver nanowires and a layer of reduced graphene oxide on the surface of the strip-shaped positive electrode.

8. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The conductivity treatment includes: electroplating a silver layer on the surface of the strip-shaped positive electrode, followed by alloying and sintering to form a copper-silver solid solution alloy layer.

9. The method for preparing a voltage-controllable perovskite photovoltaic cell according to claim 1, characterized in that, The conductivity treatment includes printing a carbon nanotube-doped silver conductive paste onto the surface of a strip-shaped positive electrode.

10. A voltage-controllable perovskite photovoltaic cell, characterized in that, It is prepared by the method described in any one of claims 1 to 9.

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