A stable composite back electrode and a preparation method and application thereof

Abstract

The present application relates to a kind of stable composite back electrode and its preparation method and application, preparation method includes by magnetron sputtering on copper substrate Nickel film is deposited, and high temperature annealing is obtained Copper-nickel alloy substrate;By chemical vapor deposition method in-situ growth graphene layer on both sides of copper-nickel alloy substrate, and on the surface of one side graphene layer Coating modified binder;After heat treatment, it is obtained Composite back electrode.Compared with prior art, the preparation method of stable composite back electrode provided by the present application, perovskite solar cell, composite back electrode and the assembly method of perovskite solar cell significantly improve the working stability of perovskite solar cell under the premise of guaranteeing high conversion efficiency, and preparation cost is low, hot-pressing process is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and relates to a stable composite back electrode, its preparation method and application. Background Technology

[0002] A solar cell is a device that directly converts light energy into electrical energy through the photovoltaic effect or photochemical reaction; it is also known as a solar cell or photovoltaic cell. Due to its excellent photoelectric performance and low-cost solution-based fabrication process, perovskite solar cells have attracted significant attention in academia and industry. Generally, its device structure includes a transparent conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer, a back electrode, and various interface modification layers. Furthermore, perovskite solar cells are typically classified into two types: a standard device structure (transparent conductive substrate / electron transport layer / perovskite active layer / hole transport layer / back electrode) and an inverted device structure (transparent conductive substrate / hole transport layer / perovskite active layer / electron transport layer / back electrode). After ten years of research, the certified efficiency of perovskite solar cells based on the standard structure has reached 25.7%, approaching the efficiency record of monocrystalline silicon cells.

[0003] However, improving the long-term operational stability of perovskite solar cells is crucial for their commercialization. Besides stabilizing the perovskite crystal structure and developing stable charge transport layer materials, designing efficient, stable, and low-cost back electrode materials is essential. Silver and aluminum are commonly used back electrode materials in perovskite solar cells, but these materials readily react with halide anions generated from perovskite decomposition, forming insulating compounds such as silver iodide and aluminum iodide, thus hindering interfacial charge transport. Even with relatively stable gold electrodes, atoms can still diffuse into the perovskite active layer, forming deep-level defects and affecting device performance. Furthermore, precious metals are expensive and typically prepared using high-vacuum, high-temperature thermal evaporation methods, significantly increasing device fabrication costs. In contrast, copper, being insensitive to perovskite composition, is a very promising stable and low-cost back electrode material and has been widely used in stable inverse perovskite solar cells. However, its low work function (4.65 eV) prevents it from forming an ohmic contact with the valence band top (~5.2 eV) of hole transport materials commonly used in commercial devices. Furthermore, copper can still be oxidized by oxygen and water to form impurities such as basic copper carbonate. Studies have shown that at 85°C, copper atoms can also diffuse into the perovskite layer, reducing device efficiency. Besides metal electrodes, intrinsically stable carbon electrodes have also been used in perovskite solar cells. Devices based on carbon electrodes have recently achieved operational stability exceeding 9000 hours at 55°C. However, due to the charge transport problems inherent in carbon electrode systems, the conversion efficiency of this type of device remains below 20%. Therefore, there is an urgent need to develop low-cost back electrode materials that combine high stability, high efficiency, and tunable work function. Summary of the Invention

[0004] The purpose of this invention is to provide a stable composite back electrode and its preparation method and application, which is used to prepare a stable, efficient, and low-cost back electrode with adjustable work function, thereby facilitating the production and manufacturing of stable and efficient perovskite solar cells.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a stable composite back electrode includes: depositing a nickel thin film on a copper substrate by magnetron sputtering and annealing it at high temperature to obtain a copper-nickel alloy substrate, which is the composite back electrode.

[0007] Furthermore, the copper substrate is pretreated before magnetron sputtering;

[0008] The pretreatment process includes: chemically polishing the copper substrate with ammonium persulfate etching solution, followed by ultrasonic cleaning and drying; wherein, during the ultrasonic cleaning process, the cleaning solution used includes at least one of deionized water, ethanol, acetone, isopropanol, acetonitrile, and n-butanol.

[0009] Furthermore, the thickness of the nickel film is 100-300 nm; during the high-temperature annealing process, the annealing temperature is 500-1500℃, the annealing time is 0.5-2h, the annealing atmosphere is an Ar / H2 mixture or an N2 / H2 mixture, and the flow rate is 20-200 sccm.

[0010] A method for preparing a stable composite back electrode includes: growing graphene layers in situ on both sides of a copper-nickel alloy substrate by chemical vapor deposition to obtain a copper-nickel alloy carbide plate, which is the composite back electrode.

[0011] The copper-nickel alloy substrate is prepared using the method described above.

[0012] Furthermore, the chemical vapor deposition process is as follows: in a mixed atmosphere containing a gaseous organic carbon source and a hydrogen-containing mixed gas, the copper-nickel alloy substrate is annealed at 500-1500℃ for 0.5-2h, and then annealed again at 500-1500℃ for 0.5-2h in a hydrogen-containing mixed gas.

[0013] In the mixed atmosphere, the gaseous organic carbon source is at least one of methane, ethane, propane, n-butane, and isobutane, and the hydrogen-containing mixed gas is an Ar / H2 mixed gas or an N2 / H2 mixed gas, with a volume flow ratio of hydrogen-containing mixed gas to methane of 20:(1-3).

[0014] A method for preparing a stable composite back electrode includes: coating a modified binder on the surface of a graphene layer on one side of a copper-nickel carbide alloy plate to form a wet adhesive layer film; then removing harmful solvents through heat treatment to form a thin and uniform interfacial adhesive layer (thickness of 1-5 nm), thereby obtaining the composite back electrode.

[0015] The copper-nickel carbide alloy plate is prepared using the method described above.

[0016] Furthermore, the method for preparing the modified adhesive includes:

[0017] M1: The conductive additive is mixed with an organic solvent and ultrasonically dispersed for 1 hour to obtain a conductive additive dispersion.

[0018] M2: The conductive additive dispersion is mixed with the binder, and after standing and swelling and stirring evenly, the modified binder is obtained.

[0019] The conductive additives include carbon nanotubes, graphene, graphylene, carbon quantum dots, and molybdenum compounds (such as MoO). X MoS X The organic solvent includes at least one of benzene, chlorobenzene, toluene, xylene, isopropanol, and acetonitrile; the concentration of the conductive additive dispersion is not higher than 6 g / L.

[0020] The adhesive comprises at least one of ethylene-vinyl acetate copolymer (EVA), polyimide, polyethylene terephthalate, polydimethylsiloxane, polybutylene terephthalate, and polyethylene naphthalate;

[0021] The conductive additive has a mass percentage of 0.4-2.4% relative to the binder;

[0022] During the static swelling process, the swelling temperature is 60-100℃ and the swelling time is 0.5-2h;

[0023] During the stirring process, the stirring temperature is 20-40℃ and the stirring time is 5-15 hours.

[0024] Furthermore, the coating process of the modified adhesive is as follows: spin coating at a speed of 4500-6500 rpm for 15-45 seconds.

[0025] Furthermore, during the heat treatment process, the heat treatment temperature is 50-100℃, and the treatment time is 30-60 minutes.

[0026] A stable composite back electrode is prepared using the method described above.

[0027] An application of a stable composite back electrode includes using the composite back electrode as the back electrode of a perovskite solar cell, wherein the perovskite solar cell comprises a transparent conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a back electrode stacked sequentially.

[0028] The electron transport layer includes one or more of TiO2, SnO2, ZnO, SrTiO3, and BaSnO3;

[0029] The hole transport layer is made of one or more of the following materials: CuI, CuSCN, CuS, CuGaO2, molybdenum oxide, MoS2, copper phthalocyanine, nickel oxide, copper-nickel composite oxide, vanadium oxide, WO3, polymers of 3-hexylthiophene, poly[bis(4-phenyl)(4-butylphenyl)amine], poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], or polycarbazole-thiophene-benzothiadiazole-thiophene.

[0030] The method for preparing the perovskite solar cell includes:

[0031] The composite back electrode is pressed onto the hole transport layer using a hot pressing method, and preferably bonded using a heat-treated modified adhesive;

[0032] During the hot pressing process, the hot pressing pressure shall not exceed 9 bar, the hot pressing temperature shall be 50-200℃, and the hot pressing time shall not exceed 180 seconds.

[0033] Compared with the prior art, the present invention has the following characteristics:

[0034] 1) The composite back electrode fabrication method of this invention employs a copper foil with high intrinsic stability for nickel alloying, making its work function suitable for high-efficiency perovskite solar cell systems. Simultaneously, this alloy can serve as a substrate for preparing a high-quality graphene barrier layer via chemical vapor deposition. Utilizing intrinsic stability and the further protection of graphene, this composite back electrode can simultaneously protect the perovskite solar cell from the effects of oxygen, moisture, and reactions of internal components of the perovskite device. By using a graphene / EVA adhesive to create an ultrathin interfacial bonding layer to further modify the back electrode, the conversion efficiency of the final perovskite solar cell device approaches 21%.

[0035] 2) The composite back electrode prepared by this invention has advantages such as adjustable work function, intrinsic chemical stability, mass production capability, and the ability to realize efficient and stable large-area perovskite devices. Based on the above stable composite back electrode, the perovskite solar cell achieves a solar power density of 100 mW / cm² under one solar radiation (AM 1.5G spectrum). -2 After 5000 hours of continuous operation, the efficiency decreases by less than 5%.

[0036] 3) The composite electrode in this invention has a manufacturing cost that is only one-third that of the thermally evaporated gold electrode, which significantly reduces the manufacturing cost of the device.

[0037] 4) The stable composite back electrode preparation method, perovskite solar cell preparation method, and composite back electrode and perovskite solar cell assembly method provided by the present invention significantly improve the working stability of perovskite solar cells while ensuring high conversion efficiency. Moreover, the composite back electrode preparation cost is low, and its corresponding hot pressing process is suitable for industrial production. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the composite back electrode (serial number 3) in Example 1;

[0039] Figure 2 The graph shows the relationship between the mass ratio of graphene nanosheets to EVA and the volume resistance of the graphene / EVA binder in Example 3.

[0040] Figure 3 This is a graph showing the relationship between hot-pressing time (0-3 min) and performance parameters of perovskite solar cells in Example 5;

[0041] Figure 4 This is a graph showing the relationship between hot-pressing pressure (0-9 bar) and performance parameters of perovskite solar cells in Example 5;

[0042] Figure 5 This is a typical device (aperture area 1.04 cm²) of the encapsulated copper-nickel carbide composite back electrode (serial number 2) and a commercially available metal electrode, as shown in Example 7. 2 Long-term operational stability test chart;

[0043] Explanation of markings in the diagram:

[0044] 1-Copper-nickel alloy substrate; 2-Graphene layer. Detailed Implementation

[0045] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0046] Comparative Example 1:

[0047] A perovskite solar cell, the preparation method of which includes the following steps:

[0048] S1: Fabrication of a transparent conductive substrate:

[0049] S1-1: A glass substrate with a fluorine-doped tin oxide conductive layer was etched using zinc powder and 6M hydrochloric acid for 15 seconds. It was then ultrasonically cleaned with deionized water, ethanol, acetone, and isopropanol for 15 minutes each. Subsequently, it was dried in dry air with nitrogen gas and subjected to ultraviolet ozone treatment at a wavelength of 185 nm, a power of 2250 W, and an irradiation time of 20 minutes, resulting in a clean, patterned transparent conductive substrate with a fluorine-doped tin oxide conductive layer.

[0050] S2: Fabrication of the electron transport layer:

[0051] S2-1: A tin oxide nanoparticle aqueous dispersion (volume ratio of tin oxide nanoparticles to water of 1:9.5) was spin-coated on a fluorine-doped indium oxide conductive layer at a speed of 3000 rpm for 30 s. The resulting electron transport layer had a thickness of about 20 nm and an average particle size of about 2 nm.

[0052] S2-2: Transfer to a heating plate and anneal at 150°C for 30 minutes. Then, perform ultraviolet ozone treatment with a wavelength of 185nm, a power of 2250W, and an irradiation time of 20 minutes to obtain an electron transport layer with a thickness of approximately 20nm.

[0053] S3: Preparation of the perovskite active layer:

[0054] S3-1: Transfer the substrate with the electron transport layer into a glove box filled with inert gas;

[0055] S3-2: Using a mixture of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) as a solvent (V DMF :V DMSO =9:1), prepare a 1.5M lead iodide solution, and then spin-coat it onto the electron transport layer at a speed of 1500 rpm for 30 s to form a lead iodide film with a thickness of about 600 nm.

[0056] S3-3: Prepare a mixed solution of isopropanol containing formamidine iodide (FAI), methylamine iodide (MAI), and methylamine chloride (MACl) (feed ratio of 90mg:9mg:9mg:1mL), and spin-coat it onto a lead iodide film at a speed of 1800rpm for 30s to obtain an intermediate phase film with a thickness of approximately 900nm;

[0057] S3-4: The substrate with the mesophase film is placed in an air environment (ambient humidity of 30-35%RH) and annealed at 150°C for 15 min to obtain a perovskite active layer with a thickness of about 850 nm.

[0058] S4: Fabrication of the hole transport layer:

[0059] S4-1: Dissolve 520 mg of lithium bis(trifluoromethanesulfonyl)imide in 1 mL of acetonitrile to obtain the first feed solution; dissolve 72.3 mg of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene in 1 mL of chlorobenzene, and then mix with 17.5 μL of the first feed solution and 28.8 μL of 4-tert-butylpyridine (tBP) to obtain the doped feed solution;

[0060] S4-2: Spin-coat the doped raw material solution onto the perovskite active layer at a speed of 3000 rpm for 30 s to obtain a hole transport layer with a thickness of approximately 150 nm.

[0061] S5: Fabrication of perovskite solar cells:

[0062] A 100 nm thick silver electrode was deposited on the hole transport layer by thermal evaporation, with a vacuum degree of approximately 7 × 10⁻⁶. - 7 Torr yielded a perovskite solar cell (pore area 1.04 cm²). 2 Its performance parameters are as follows:

[0063] J SC =24.95mA cm -2 V OC =1.102V, FF=0.76, Eff.=20.89%.

[0064] Example 1:

[0065] A stable copper-nickel composite back electrode for perovskite solar cells is prepared by the following steps:

[0066] 1) Immerse a 1μm thick copper foil in a 0.2M ammonium persulfate aqueous etching solution and perform chemical polishing for 3 minutes;

[0067] 2) After removal, the copper foil is ultrasonically cleaned sequentially with deionized water, ethanol, acetone and isopropanol for 15 minutes each. Then it is dried in an oven at 70°C for 30 minutes to obtain the pretreated copper foil.

[0068] 3) The vacuum level of the chamber body is 1.5 × 10⁻⁶ using magnetron sputtering with DC sputtering. -7 Torr, with Ni of 99.99% purity as the target material, sputtering with an argon-oxygen mixture of 1:1 and a sputtering power of 120W, formed nickel layers of 100, 200, and 300 nm thicknesses on three pretreated copper foils, respectively. Then, under a 100 sccm Ar / H2 mixed reducing atmosphere (volume ratio 1:1), the electrodes were annealed at 1000 °C for 1 h to obtain a copper-nickel composite back electrode. Its work function is shown in Table 1.

[0069] 4) The copper-nickel composite back electrode was hot-pressed onto the functional layer—hole transport layer of the perovskite solar cell at 130℃ and 3 bar pressure (the preparation method of the rest is the same as that of Comparative Example 1). The hot-pressing time was 1 min, and the perovskite solar cell was obtained. Its performance parameters are shown in Table 1.

[0070] Table 1. Effects of different nickel layer thicknesses on the work function of the copper-nickel composite back electrode and the performance of perovskite solar cells (aperture area 1.04 cm²). 2 Impact of performance parameters

[0071]

[0072]

[0073] The testing method was as follows: a solar simulator (AM1.5G, 100mW cm) was used. -2 The solar cell parameters were obtained by measuring the current-voltage curve (JV) using a Wacom Denso Co., Japan, and a Keithley 2400 digital source meter. The solar simulator was calibrated using a standard silicon reference cell. The voltage range measured by the JV curve is -0.2V to 1.2V. WF: Work function; J SC Short-circuit current density; V OC : Open-circuit voltage; FF: Fill factor; Eff.: Conversion efficiency of perovskite solar cells.

[0074] As shown in the table above, when the nickel layer thickness is 200 nm, the work function of the copper-nickel composite back electrode exhibits optimal energy level matching with the valence band top of commonly used hole transport materials in conventional perovskite solar cells (such as CuI, CuSCN, CuS, CuGaO2, molybdenum oxide, MoS2, copper phthalocyanine, nickel oxide, copper-nickel composite oxide, vanadium oxide, WO3, polymers of 3-hexylthiophene, poly[bis(4-phenyl)(4-butylphenyl)amine], poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], or polycarbazole-thiophene-benzothiadiazole-thiophene). The corresponding perovskite solar cell exhibits the highest conversion efficiency, indicating that this device achieves optimal charge transport and collection.

[0075] Example 2:

[0076] A stable copper-nickel carbide composite back electrode for perovskite solar cells is prepared by the following steps:

[0077] 1) Immerse a 1μm thick copper foil in a 0.2M ammonium persulfate aqueous etching solution and perform chemical polishing for 3 minutes;

[0078] 2) After removal, the copper foil is ultrasonically cleaned sequentially with deionized water, ethanol, acetone and isopropanol for 15 minutes each. Then it is dried in an oven at 70°C for 30 minutes to obtain the pretreated copper foil.

[0079] 3) The vacuum level of the chamber body is 1.5 × 10⁻⁶ using magnetron sputtering with DC sputtering. -7 Torr, with Ni of 99.99% purity as the target material, sputtering with an argon-oxygen mixture of 1:1 and a sputtering power of 120W, forms a 200nm thick nickel layer on the pretreated copper foil. Then, it is annealed at 1000℃ for 1h in a 100sccm Ar / H2 mixed reducing atmosphere (volume ratio 1:1) to obtain a copper-nickel composite back electrode.

[0080] 4) Keeping the Ar / H2 mixed reducing gas flow rate constant, methane was introduced as the first organic carbon source at flow rates of 5, 10, and 15 sccm, respectively. Annealing was performed at 1000℃ for 0.5 h, then the methane flow was stopped, and the mixture was held at 1000℃ for 1 h to obtain a copper-nickel carbide composite back electrode. Its structure can be found in the attached diagram. Figure 1 The work functions are shown in Table 2;

[0081] 5) The copper-nickel carbide composite back electrode was hot-pressed onto the functional layer—hole transport layer of the perovskite solar cell at 130℃ and 3 bar pressure (the preparation method of the rest is the same as that of Comparative Example 1). The hot-pressing time was 1 min, and the perovskite solar cell was obtained. Its performance parameters are shown in Table 2.

[0082] Table 2. Effects of different methane flow rates on the work function of the copper-nickel carbide composite back electrode and the performance of the perovskite solar cell (pore area 1.04 cm²). 2 Impact of performance parameters

[0083]

[0084] Among them, J SC Short-circuit current density; V OC : Open-circuit voltage; FF: Fill factor; Eff.: Conversion efficiency of the perovskite solar cell. The test method is the same as in Example 1.

[0085] As can be seen from the table above, when the methane flow rate is 10 sccm, the graphene layer (serial number 2) grown in situ on the surface of copper-nickel alloy substrate 1 has high quality and can improve all performance parameters of perovskite solar cells, such as current density, voltage and fill factor.

[0086] Example 3:

[0087] This embodiment provides a method for preparing a graphene / EVA binder for assembling composite back electrodes and perovskite solar cells, including the following steps:

[0088] 1) Add 0-6 mg of graphene nanosheets to 10 mL of xylene and ultrasonically disperse for 1 h to form a graphene dispersion;

[0089] 2) Add 0.25g of EVA to the graphene dispersion, transfer it to an 80℃ oven and let it stand for 1 hour to swell, then stir for 10 hours at a stirring temperature of 25℃ to form uniform graphene nanosheet modified EVA (graphene / EVA binder).

[0090] The samples were divided into multiple experimental groups based on different mass ratios of graphene nanosheets to EVA, and the volume resistance of the resulting adhesives was tested using a dual-electrical-meter digital four-probe tester (ST2263 model). The test results are as follows: Figure 2 As shown.

[0091] As shown in the figure, when the relative mass ratio of graphene nanosheets is 1.6%, a stable conductive network has been formed in the graphene / EVA binder, and its bulk resistance has decreased by 7.5 orders of magnitude.

[0092] Example 4:

[0093] This embodiment provides a composite back electrode based on the graphene / EVA binder in Example 3 and a large-area perovskite solar cell (pore area 1.04 cm²). 2 The assembly method includes the following steps:

[0094] 1) Spin-coat 1 mL of EVA (serial number 1) or graphene / EVA binder (the relative mass ratio of graphene nanosheets is 1.6%, serial number 2) onto the copper-nickel carbide composite back electrode in Example 3 at a speed of 5500 rpm (carbon source flow rate 10 sccm). The spin-coating time is 30 s. Then anneal at 70 °C for 30 min to obtain a copper-nickel carbide composite back electrode with a binder layer.

[0095] 2) The hole transport layer, the functional layer of the perovskite solar cell, was hot-pressed at 130℃ and 3 bar onto the other parts using the same method as in Comparative Example 1. This allowed the hole transport layer to adhere to one side of the copper-nickel carbide composite back electrode bonding layer. The hot-pressing time was 1 min, resulting in a pore area of ​​1.04 cm². 2 The performance parameters of the perovskite solar cell are shown in Table 3.

[0096] Table 3. Effects of binder modification on performance parameters of perovskite solar cells

[0097]

[0098] Among them, JSC Short-circuit current density; V OC : Open-circuit voltage; FF: Fill factor; Eff.: Conversion efficiency of perovskite solar cells.

[0099] This demonstrates that modifying the binder can significantly improve the performance of large-area perovskite devices, achieving a large-area device efficiency of nearly 21%.

[0100] Example 5:

[0101] This embodiment is used to investigate the effects of hot-pressing pressure (0-9 bar) and hot-pressing time (0-3 min) on the performance parameters of perovskite solar cells;

[0102] The binder used was a graphene / EVA binder with a graphene nanosheet mass ratio of 1.6%, and the rest was the same as in Example 4.

[0103] Device series resistance (R) S The results of hot pressing time and pressure are as follows: Figure 3 , Figure 4 As shown. The series resistance of the device is based on a solar simulator (AM1.5G, 100mW cm). -2 The current-voltage curve (JV) was measured using a Wacom Denso Co., Japan and a Keithley 2400 digital source meter.

[0104] As shown in the figure, efficient charge transfer can be achieved using a hot-pressing pressure of 3 bar and a hot-pressing time of 1 minute. Excessive hot-pressing pressure and time may damage the perovskite and hole transport layer. Therefore, while ensuring charge transfer, the lowest possible pressure and shortest possible hot-pressing time should be selected.

[0105] Example 6:

[0106] This embodiment is used to compare and examine the work function and typical device (pore area 1.04 cm²) of the copper-nickel carbide composite back electrode (serial number 2) prepared in Example 2 with that of a commercially available metal electrode (Fujian Infineon Materials Co., Ltd.). 2The conversion efficiency and cost differences are shown in Table 4. Normalized cost refers to the cost of other electrodes (gold electrode: Lusheng, Liang, et al. All that glitters is not gold: Recent progress of alternative counter electrodes for perovskite solar cells[J]. Nano Energy, 2018.) obtained while ensuring device performance. Silver electrode was not selected for comparison because its stability differs significantly from gold and composite electrodes, making the comparison less meaningful. The cost of gold electrode includes raw materials, thermal evaporation, and equipment depreciation. The cost of composite electrode includes raw materials, magnetron sputtering, chemical vapor deposition, and equipment depreciation. All cost values ​​are based on actual laboratory preparation costs and depreciation.

[0107] Table 4

[0108] Composite electrode 5.1 21％ 1 gold 5.0 21％ 3.3

[0109] Therefore, it can be seen that, while ensuring the high conversion efficiency of perovskite devices, composite electrodes have a work function that is more compatible with hole transport materials, and their manufacturing cost is only 1 / 3 of that of commercial gold electrodes, which can effectively reduce the corresponding component costs.

[0110] Example 7:

[0111] This example is used to compare and examine the pore area of ​​1.04 cm² prepared in Example 2. 2 The differences in typical device conversion efficiency and long-term stability between the copper-nickel carbide composite back electrode (serial number 2) and the commercially available metal electrode (Fujian Infineon Materials Co., Ltd.) are shown in Table 5. The long-term stability testing system was a solar cell photoresistance testing system manufactured by Bunkoukeiki, Japan, and the testing conditions were an AM1.5G solar spectrum and 100mW cm⁻¹. -2 .

[0112] Specifically, Figure 5 This is a typical device (aperture area 1.04 cm²) using a packaged copper-nickel carbide composite back electrode (serial number 2) and a commercially available metal electrode (Fujian Infineon Materials Co., Ltd.). 2The results of long-term operational stability tests are as follows: Silver electrode devices (Ag devices) retained only 30% of their original efficiency after 500 hours of operation; gold electrode devices (Au devices), while exhibiting operational stability for 1500 hours, subsequently showed significant degradation; even devices using chemically stable carbon electrodes (SG devices) retained only about 60% of their initial efficiency after 2000 hours of operation. In contrast, copper-nickel carbide composite back electrode devices (CNG-10 devices) achieved operational stability for over 5000 hours, with the packaged devices retaining 95% of their initial efficiency after 5000 hours of continuous operation.

[0113] Table 5

[0114]

[0115]

[0116] It can be seen that the composite electrode can effectively collect interfacial charge. While ensuring the high conversion efficiency of the device, the graphene layer grown in situ effectively blocks the attack of perovskite components on the electrode, achieving working stability for up to 5000 hours.

[0117] Example 8:

[0118] This embodiment is used to compare and examine the copper-nickel carbide composite back electrode (serial number 2) prepared in Example 2 with the device based on a graphite layer prepared by screen printing in CN201580015052.9 (pore area 1.04 cm²). 2 The differences in device performance are shown in Table 6.

[0119] Table 6

[0120] Composite electrode 24.68 1.112 0.76 20.86 Screen printing graphite 22.70 1.101 0.72 17.99

[0121] Therefore, compared to devices based on graphite electrodes fabricated by screen printing, perovskite devices based on composite electrodes exhibit superior short-circuit current and fill factor, achieving a high conversion efficiency of nearly 21%. This demonstrates that composite electrodes can effectively avoid the charge accumulation problem inherent in printed graphite electrodes, significantly improving device efficiency.

[0122] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method of making a stable composite back electrode, characterized by, The preparation method includes: depositing a nickel thin film on a copper substrate by magnetron sputtering, followed by high-temperature annealing to obtain a copper-nickel alloy substrate; A copper-nickel alloy carbide plate was obtained by in-situ growth of graphene layers on both sides of a copper-nickel alloy substrate using chemical vapor deposition. A modified binder is coated on the surface of the graphene layer on one side of a copper-nickel carbide alloy plate, and then heat-treated to form a composite back electrode. The method for preparing the modified adhesive includes: M1: The conductive additive is mixed with an organic solvent to obtain a conductive additive dispersion; M2: The conductive additive dispersion is mixed with the binder, and after standing and swelling and stirring evenly, the modified binder is obtained. The conductive additive is graphene; the organic solvent includes at least one of benzene, chlorobenzene, toluene, xylene, isopropanol, and acetonitrile; the concentration of the conductive additive dispersion is not higher than 6 g / L. The adhesive is an ethylene-vinyl acetate copolymer; The conductive additive has a mass percentage of 0.4-2.4% relative to the binder. During the static swelling process, the swelling temperature is 60-100℃ and the swelling time is 0.5-2h; During the stirring process, the stirring temperature is 20-40℃, and the stirring time is 5-15 hours; During the heat treatment process, the heat treatment temperature is 50-100℃ and the treatment time is 30-60min.

2. The method of claim 1, wherein the stable composite back electrode is prepared by the steps of: The copper substrate is pretreated before magnetron sputtering; The pretreatment process includes: chemically polishing the copper substrate with ammonium persulfate etching solution, followed by ultrasonic cleaning and drying; wherein, during the ultrasonic cleaning process, the cleaning solution used includes at least one of deionized water, ethanol, acetone, isopropanol, acetonitrile, and n-butanol.

3. The method of claim 1, wherein the stable composite back electrode is prepared by the steps of: The nickel film thickness is 100-300 nm; during the high-temperature annealing process, the annealing temperature is 500-1500℃, the annealing time is 0.5-2 h, and the annealing atmosphere is an Ar / H2 mixture or an N2 / H2 mixture.

4. The method of claim 1, wherein the stable composite back electrode is prepared by the steps of: The chemical vapor deposition process is as follows: in a mixed atmosphere containing a gaseous organic carbon source and a hydrogen-containing mixed gas, the copper-nickel alloy substrate is annealed at 500-1500℃ for 0.5-2h, and then annealed again at 500-1500℃ for 0.5-2h in a hydrogen-containing mixed gas. In the mixed atmosphere, the gaseous organic carbon source is at least one of methane, ethane, propane, n-butane, and isobutane, and the hydrogen-containing mixed gas is an Ar / H2 mixed gas or an N2 / H2 mixed gas, with a volume flow ratio of hydrogen-containing mixed gas to methane of 20:(1-3).

5. A stable composite back electrode characterized in that, It is prepared by the method described in any one of claims 1 to 4.

6. Use of a stable composite back electrode according to claim 5, characterized in that The composite back electrode is used as the back electrode of a perovskite solar cell, which includes a transparent conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a back electrode stacked sequentially. The method for preparing the perovskite solar cell includes: The composite back electrode is pressed onto the hole transport layer using a hot-pressing method; During the hot pressing process, the hot pressing pressure shall not exceed 9 bar, the hot pressing temperature shall be 50-200℃, and the hot pressing time shall not exceed 180 seconds.

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