Carbon electrode and preparation method and application thereof

Abstract

The invention provides a carbon electrode and a preparation method and application thereof. The preparation method comprises the following steps: coating a substrate with carbon slurry to obtain a wet carbon film, and then coating the wet carbon film with liquid alkane to obtain the carbon electrode. The liquid alkane is introduced to the surface of the wet carbon film, and by means of the characteristic that the liquid alkane and the solvent of the carbon slurry are immiscible, the boiling point of a double-liquid system is reduced, the volatilization speed of the solvent in the carbon slurry is increased, the curing temperature of the carbon electrode is further reduced, and perovskite can be prevented from being decomposed at high temperature; and the damage of the solvent in the carbon slurry to the perovskite layer and other functional layers is greatly reduced, so that the efficiency of the subsequently prepared perovskite solar cell or laminated solar cell is remarkably improved. In addition, the preparation method is simple in process and low in cost, and has good development potential.

Description

Technical Field

[0001] This invention belongs to the field of solar energy technology, specifically relating to a carbon electrode, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells, as an emerging photovoltaic technology, have attracted widespread attention due to their excellent photoelectric performance, low cost, and simple fabrication process. Furthermore, perovskite's tunable bandgap allows it to be used in perovskite / crystalline silicon tandem cells, with a theoretical efficiency exceeding 45%, and a current high efficiency of 34.6%, making it considered a next-generation mainstream photovoltaic technology.

[0003] However, current perovskite / crystalline silicon tandem solar cells still primarily use the silver electrode found in crystalline silicon cells, typically fabricating silver grid lines on the light-incident surface via screen printing. The silver grid lines collect and transport photogenerated carriers, but they also block some sunlight, leading to efficiency loss. While silver grid lines are well-established in crystalline silicon cells, in perovskite / crystalline silicon tandem cells, even with low-temperature silver paste, the curing temperature remains excessively high (>170℃). Furthermore, the solvents used in silver pastes often contain alcohols, which can penetrate the transport layer and perovskite layer, damaging the functional layers; the high curing temperature further accelerates this process.

[0004] Therefore, how to avoid damage to the perovskite and other functional layers caused by high temperatures and solvents during the electrode deposition process, and improve device performance, is an urgent technical problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a carbon electrode, its preparation method, and its applications. This invention introduces liquid alkanes onto the surface of a wet carbon film. Utilizing the immiscibility of the liquid alkanes with the carbon slurry solvent, the boiling point of the two-liquid system is lowered, accelerating the evaporation rate of the solvent in the carbon slurry and further reducing the curing temperature of the carbon electrode, thus preventing the decomposition of perovskite at high temperatures. Furthermore, it significantly reduces the damage to the perovskite layer and other functional layers caused by the solvent in the carbon slurry, resulting in a significant improvement in the efficiency of subsequently fabricated perovskite solar cells or tandem solar cells. In addition, this preparation method is simple, low-cost, and has good development potential.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a carbon electrode, the method comprising the following steps:

[0008] A carbon slurry is coated onto a substrate to obtain a wet carbon film, and then liquid alkane is coated onto the wet carbon film to obtain the carbon electrode.

[0009] It should be noted that the greater the thickness of the carbon electrode, the smaller the sheet resistance, and the less energy is lost at the electrode. Common methods typically involve annealing to directly remove the solvent, thus converting the wet film into a dry film. However, as the carbon electrode thickness increases, the corresponding annealing temperature also increases.

[0010] To address this, the present invention introduces liquid alkanes onto the surface of the wet carbon film. Utilizing the immiscibility of the liquid alkanes with the carbon slurry solvent, the boiling point of the two-liquid system is lowered, accelerating the evaporation rate of the solvent in the carbon slurry and further reducing the curing temperature of the carbon electrode, thus preventing the perovskite from decomposing at high temperatures. Furthermore, it significantly reduces the damage to the perovskite layer and other functional layers caused by the solvent in the carbon slurry, resulting in a significant improvement in the efficiency of the subsequently fabricated perovskite solar cells or tandem solar cells. In addition, this fabrication method is simple, low-cost, and has good development potential.

[0011] It should be noted that if the degree of miscibility between the two liquids is very small and can be ignored, they can be approximated as forming an immiscible binary system. In such a binary system, as long as both liquids are present, the vapor pressure of the system is higher than the vapor pressure of either pure component, meaning the boiling point of the system is lower than the boiling point of either pure component, regardless of the proportion of the components.

[0012] It should be noted that the present invention does not limit the substrate. For example, it may be a glass substrate, a crystalline silicon substrate, or a glass substrate on which a perovskite solar cell functional layer has been deposited.

[0013] Preferably, the carbon slurry comprises carbon material and solvent.

[0014] Preferably, the carbon material in the carbon slurry includes any one or a combination of at least two of graphite, carbon black, carbon nanotubes, carbon fibers, or graphene.

[0015] Preferably, the solvent of the carbon slurry includes any one or a combination of at least two of the following: water, methanol, acrylic resin, diethylene glycol butyl ether, diethylene glycol propyl ether, propylene glycol methyl ether, or terpineol.

[0016] Preferably, the viscosity of the carbon slurry is 1000-30000 cps, for example, it can be 1000 cps, 5000 cps, 10000 cps, 15000 cps, 20000 cps, 25000 cps or 30000 cps, etc.

[0017] Preferably, the solid content of the carbon slurry is 20-80 wt%, for example, it can be 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt%.

[0018] Preferably, the carbon paste is coated by screen printing.

[0019] Preferably, the specific steps of the screen printing method include:

[0020] Carbon paste is poured into one end of the screen, and a squeegee is used to apply pressure to the carbon paste area of ​​the screen while moving it towards the other end of the screen. This causes the carbon paste to be squeezed from the mesh of the patterned area onto the substrate by the squeegee during the movement, thereby forming a wet carbon film.

[0021] Preferably, the thickness of the wet carbon film is 10-100 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0022] Preferably, the liquid alkane includes any one or a combination of at least two of cyclohexane, cyclopentane, n-hexane, n-pentane, n-heptane, or isooctane, and is more preferably cyclopentane and / or n-pentane.

[0023] It should be noted that the preferred liquid alkanes meet the following three conditions: (1) they are immiscible with the main solvent of the carbon paste; (2) they have a low boiling point; and (3) they will not damage the perovskite layer.

[0024] Preferably, the liquid alkane is coated by screen printing.

[0025] Preferably, the specific steps of the screen printing method include:

[0026] Replace the screen with another one, with the same pattern as the screen used to prepare the wet carbon film. Then, pour liquid alkane into one end of the screen and apply pressure to the liquid alkane portion of the screen with a scraper while moving it toward the other end. This causes the liquid alkane to be squeezed from the mesh of the patterned portion onto the surface of the wet carbon film by the scraper during the movement. Repeat the above steps 10-500 times (e.g., 10, 50, 100, 200, 300, 400, or 500 times, etc.).

[0027] Preferably, during the liquid alkane coating process, the temperature of the substrate is controlled at 30-50℃, for example, it can be 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃ or 50℃, etc.

[0028] In this invention, if the temperature of the substrate is too low, the solvent in the carbon paste cannot be completely removed, resulting in solvent residue. Over time, this residue will penetrate into the functional layer of the perovskite solar cell, thereby damaging the functional layer. If the temperature of the substrate is too high, it will accelerate the penetration of the solvent in the carbon paste into the perovskite layer and other functional layers, resulting in a decrease in both the open-circuit voltage and current density of the device.

[0029] In a second aspect, the present invention provides a carbon electrode, which is prepared by the preparation method described in the first aspect.

[0030] Thirdly, the present invention provides a perovskite solar cell, the perovskite solar cell comprising a conductive substrate, a perovskite light-absorbing layer, an electron transport layer and a carbon electrode as described in the second aspect, all stacked together.

[0031] Preferably, the conductive substrate comprises conductive glass. For example, the conductive glass may be ITO (indium tin oxide) conductive glass, FTO (fluorine-doped tin oxide) conductive glass, or IZO (indium zinc oxide) conductive glass, etc.

[0032] Preferably, the chemical formula of the perovskite light-absorbing layer is ABX3, wherein A includes any one or a combination of at least two of formamidinium ions, methylamine ions, or cesium ions, B includes lead ions, and X includes any one or a combination of at least two of chloride ions, bromide ions, or iodide ions.

[0033] Preferably, a hole transport layer is further disposed between the conductive substrate and the perovskite light-absorbing layer, the hole transport layer comprising a nickel oxide layer and / or a monomolecular self-assembled layer.

[0034] Preferably, the electron transport layer includes C 60 Layer and / or SnO2 layer.

[0035] Thirdly, the present invention provides a tandem solar cell, the tandem solar cell comprising a crystalline silicon base cell, a tunneling layer, a first charge transport layer, a perovskite light-absorbing layer, a second charge transport layer, and a carbon electrode as described in the second aspect, all stacked together.

[0036] Preferably, the crystalline silicon bottom cell includes a stacked metal back electrode, an ITO layer, a p-type amorphous silicon layer, a first amorphous silicon intrinsic layer, a monocrystalline silicon layer, a second amorphous silicon intrinsic layer, and an n-type amorphous silicon layer, wherein the n-type amorphous silicon layer is close to the tunneling layer.

[0037] Preferably, the metal back electrode includes an Ag gate electrode.

[0038] Preferably, the thickness of the ITO layer is 5-30nm, for example, it can be 5nm, 10nm, 15nm, 20nm, 25nm or 30nm.

[0039] Preferably, the thickness of the p-type amorphous silicon layer and the n-type amorphous silicon layer are each independently 5-15 nm, for example, 5 nm, 10 nm or 15 nm.

[0040] Preferably, the tunneling layer comprises an ITO layer or an IZO (indium zinc oxide) layer.

[0041] Preferably, the thickness of the tunneling layer is 5-30nm, for example, it can be 5nm, 10nm, 15nm, 20nm, 25nm or 30nm.

[0042] Preferably, the charges transported by the first charge transport layer and the second charge transport layer are of opposite polarity.

[0043] Preferably, the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer.

[0044] Preferably, the hole transport layer comprises a monomolecular self-assembled layer and / or a nickel oxide layer. For example, the monomolecular self-assembled layer may be a [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid layer.

[0045] Preferably, the electron transport layer includes C 60 The layer and / or SnO2 layer have a thickness of 20-50nm, for example, it can be 20nm, 30nm, 40nm or 50nm, etc.

[0046] Preferably, the perovskite light-absorbing layer is a wide-bandgap perovskite light-absorbing layer with a thickness of 300-1000nm, such as 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm.

[0047] Preferably, a buffer layer and a protective layer are further stacked between the second charge transport layer and the carbon electrode, with the buffer layer close to the second charge transport layer and the protective layer close to the carbon electrode.

[0048] Preferably, the buffer layer includes a SnO2 layer with a thickness of 5-20 nm, for example, it can be 5 nm, 10 nm, 15 nm or 20 nm.

[0049] Preferably, the protective layer includes an ITO layer with a thickness of 40-80 nm, such as 40 nm, 50 nm, 60 nm, 70 nm or 80 nm.

[0050] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The present invention introduces liquid alkanes on the surface of wet carbon film. By taking advantage of the immiscibility between liquid alkanes and carbon paste solvents, the boiling point of the two-liquid system is reduced, the evaporation rate of solvents in carbon paste is accelerated, and the curing temperature of carbon electrode is further reduced, thereby reducing the impact on the device during electrode printing and curing. Furthermore, the damage of solvents in carbon paste to perovskite layer and other functional layers is greatly reduced, resulting in a significant improvement in the efficiency of subsequent perovskite solar cells or tandem solar cells.

[0053] (2) The preparation method provided by the present invention is simple and low in cost, and has good development potential. Attached Figure Description

[0054] Figure 1 The process flow diagram for preparing the carbon electrode provided by this invention.

[0055] Figure 2 This is a schematic diagram of the structure of the stacked solar cell provided by the present invention.

[0056] Among them, 1-screen; 2-carbon slurry; 3-scraper; 4-substrate; 5-liquid alkane; 6-crystalline silicon bottom cell; 7-tunneling layer; 8-hole transport layer; 9-wide bandgap perovskite light-absorbing layer; 10-electron transport layer; 11-buffer layer; 12-protective layer; 13-carbon electrode. Detailed Implementation

[0057] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0058] Example 1

[0059] This embodiment provides a method for preparing a carbon electrode, the process flow diagram of which is shown below. Figure 1 As shown, the preparation method includes the following steps:

[0060] (1) The carbon paste 2 is printed onto the substrate 4 using screen printing process 1 to obtain a wet carbon film. The specific printing steps include:

[0061] Carbon paste 2 is poured into one end of the screen 1. A certain pressure is applied to the carbon paste 2 part of the screen 1 with a scraper 3, while moving towards the other end of the screen 1. This causes the carbon paste 2 to be squeezed from the mesh of the pattern part onto the substrate 4 by the scraper 3 during the movement, thereby forming a wet carbon film with a thickness of 10μm.

[0062] The carbon slurry 2 comprises a carbon material and a solvent, wherein the carbon material is graphite, the solvent is methanol, the slurry viscosity of the carbon slurry 2 is 15000 cps, and the solid content of the carbon slurry 2 is 20 wt%.

[0063] (2) Then, liquid alkane 5 is printed onto the wet carbon film using screen printing process 1 to obtain the carbon electrode. The specific printing steps include:

[0064] The substrate temperature of the substrate 4 obtained in the adsorption step (1) is controlled at 30°C. Then, a screen is placed on the surface of the wet carbon film, and its pattern is exactly the same as that of the screen 1 used to prepare the wet carbon film. Liquid alkane 5 is poured into one end of the screen 1. A certain pressure is applied to the liquid alkane 5 part of the screen 1 with a scraper 3, while moving towards the other end of the screen 1, so that the liquid alkane 5 is squeezed from the mesh of the pattern part to the surface of the wet carbon film by the scraper 3 during the movement. Repeat the above steps 10 times.

[0065] Among them, liquid alkane 5 is cyclopentane.

[0066] Example 2

[0067] This embodiment provides a method for preparing a carbon electrode, the method comprising the following steps:

[0068] (1) The carbon paste is printed onto the substrate using screen printing technology to obtain a wet carbon film. The specific printing steps include:

[0069] Carbon paste is poured into one end of the screen, and a squeegee is used to apply pressure to the carbon paste area of ​​the screen while moving towards the other end of the screen. This causes the carbon paste to be squeezed from the mesh of the patterned area onto the substrate by the squeegee during the movement, thereby forming a wet carbon film with a thickness of 50μm.

[0070] The carbon slurry comprises carbon material and solvent, wherein the carbon material is carbon black, the solvent is diethylene glycol butyl ether, the slurry viscosity of the carbon slurry is 20000 cps, and the solid content of the carbon slurry is 50 wt%.

[0071] (2) Then, liquid alkane is printed onto the wet carbon film using a screen printing process to obtain the carbon electrode. The specific printing steps include:

[0072] The substrate temperature of the substrate obtained in the adsorption step (1) is controlled at 40°C. Then, a screen is placed on the surface of the wet carbon film, and its pattern is exactly the same as that of the screen used to prepare the wet carbon film. Liquid alkanes are poured into one end of the screen, and a certain pressure is applied to the liquid alkanes part of the screen with a scraper while moving towards the other end of the screen. This allows the liquid alkanes to be squeezed from the mesh of the patterned part onto the surface of the wet carbon film by the scraper during the movement. Repeat the above steps 200 times.

[0073] The liquid alkane is n-pentane.

[0074] Example 3

[0075] This embodiment provides a method for preparing a carbon electrode, the method comprising the following steps:

[0076] (1) The carbon paste is printed onto the substrate using screen printing technology to obtain a wet carbon film. The specific printing steps include:

[0077] Carbon paste is poured into one end of the screen, and a certain pressure is applied to the carbon paste area of ​​the screen with a scraper while moving towards the other end of the screen. This causes the carbon paste to be squeezed from the mesh of the patterned area onto the substrate by the scraper during the movement, thereby forming a wet carbon film with a thickness of 100μm.

[0078] The carbon slurry comprises carbon material and solvent, wherein the carbon material is carbon nanotubes, the solvent is propylene glycol methyl ether, the slurry viscosity is 30,000 cps, and the solid content of the carbon slurry is 80 wt%.

[0079] (2) Then, liquid alkane is printed onto the wet carbon film using a screen printing process to obtain the carbon electrode. The specific printing steps include:

[0080] The substrate temperature of the substrate obtained in the adsorption step (1) is controlled at 50°C. Then, a screen is placed on the surface of the wet carbon film, and its pattern is exactly the same as that of the screen used to prepare the wet carbon film. Liquid alkanes are poured into one end of the screen, and a certain pressure is applied to the liquid alkanes part of the screen with a scraper while moving towards the other end of the screen. This allows the liquid alkanes to be squeezed from the mesh of the patterned part onto the surface of the wet carbon film by the scraper during the movement. Repeat the above steps 500 times.

[0081] The liquid alkane is cyclohexane.

[0082] Example 4

[0083] The difference between this embodiment and embodiment 1 is that the liquid alkane in step (2) is cyclohexane.

[0084] The remaining preparation methods and parameters are consistent with those in Example 1.

[0085] Example 5

[0086] The difference between this embodiment and embodiment 1 is that the liquid alkane in step (2) is n-pentane.

[0087] The remaining preparation methods and parameters are consistent with those in Example 1.

[0088] Example 6

[0089] The difference between this embodiment and embodiment 1 is that the liquid alkane in step (2) is n-hexane.

[0090] The remaining preparation methods and parameters are consistent with those in Example 1.

[0091] Example 7

[0092] The difference between this embodiment and embodiment 1 is that the substrate temperature in step (2) is controlled at 40°C.

[0093] The remaining preparation methods and parameters are consistent with those in Example 1.

[0094] Example 8

[0095] The difference between this embodiment and embodiment 1 is that the substrate temperature in step (2) is controlled at 50°C.

[0096] The remaining preparation methods and parameters are consistent with those in Example 1.

[0097] Example 9

[0098] The difference between this embodiment and embodiment 1 is that the substrate temperature in step (2) is controlled at room temperature (i.e., 25°C).

[0099] The remaining preparation methods and parameters are consistent with those in Example 1.

[0100] Example 10

[0101] The difference between this embodiment and embodiment 1 is that the substrate temperature in step (2) is controlled at 60°C.

[0102] The remaining preparation methods and parameters are consistent with those in Example 1.

[0103] Comparative Example 1

[0104] The difference between this comparative example and Example 1 is that step (2) is omitted, and the wet carbon film obtained in step (1) is directly dried at 120°C for 15 minutes to obtain the carbon electrode.

[0105] The remaining preparation methods and parameters are consistent with those in Example 1.

[0106] Comparative Example 2

[0107] The difference between this comparative example and Example 1 is that the liquid alkane in step (2) is replaced with chloroform.

[0108] The remaining preparation methods and parameters are consistent with those in Example 1.

[0109] Application Example 1

[0110] This application example provides a tandem solar cell, the structural schematic of which is shown below. Figure 2 As shown, the stacked solar cell includes a crystalline silicon base cell 6, a tunneling layer 7, a hole transport layer 8, a wide-bandgap perovskite light-absorbing layer 9, an electron transport layer 10, a buffer layer 11, a protective layer 12, and a carbon electrode 13 stacked together. The carbon electrode 13 is prepared using the preparation method described in Example 1.

[0111] The crystalline silicon bottom cell 6 includes stacked silver grid electrodes, an ITO layer, a p-type amorphous silicon layer, a first amorphous silicon intrinsic layer, an n-type monocrystalline silicon layer, a second amorphous silicon intrinsic layer, and an n-type amorphous silicon layer. The n-type amorphous silicon layer is close to the tunneling layer 7. The thickness of the ITO layer is 15 nm, the thickness of the p-type amorphous silicon layer and the n-type amorphous silicon layer are both 8 nm, and the thickness of the first amorphous silicon intrinsic layer and the second amorphous silicon intrinsic layer are both 10 nm.

[0112] The tunneling layer 7 is an ITO layer with a thickness of 15 nm;

[0113] The hole transport layer 8 is stacked sequentially with a nickel oxide layer and a self-assembled layer of 15 nm thickness along the direction away from the tunneling layer 7. The material of the self-assembled layer is [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid.

[0114] The chemical formula of the wide-bandgap perovskite light-absorbing layer 9 is Cs. 0.22 FA 0.78 Pb(I 0.85 Br 0.15 )3, the wide-bandgap perovskite light-absorbing layer 9 is doped with 5 wt% MAPbCl3, and the thickness of the wide-bandgap perovskite light-absorbing layer 9 is 600 nm;

[0115] The electron transport layer 10 is a C material with a thickness of 20 nm. 60 The buffer layer 11 is a SnO2 layer with a thickness of 17 nm, and the protective layer 12 is an ITO layer with a thickness of 55 nm.

[0116] This application example also provides a method for fabricating the above-mentioned tandem solar cell, the method comprising the following steps:

[0117] (1) Clean the textured n-type monocrystalline silicon, and then deposit an amorphous silicon intrinsic layer on each side of the textured surface of the n-type monocrystalline silicon by plasma-enhanced chemical vapor deposition. Then, deposit a p-type amorphous silicon layer on the amorphous silicon intrinsic layer on one side by low-temperature plasma-enhanced chemical vapor deposition (PECVD) and deposit an n-type amorphous silicon layer on the amorphous silicon intrinsic layer on the other side. Then, deposit an ITO layer on the p-type amorphous silicon layer by magnetron sputtering. Deposit a tunneling layer 7 of ITO material on the n-type amorphous silicon layer. Then, prepare silver gate electrode on the ITO layer by screen printing.

[0118] (2) A nickel oxide layer is deposited on the tunneling layer 7 by magnetron sputtering, followed by the deposition of a self-assembled layer of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid by wet deposition. A wide-bandgap perovskite light-absorbing layer 9 is then coated onto the self-assembled layer, and finally, C is deposited on the wide-bandgap perovskite light-absorbing layer 9 by vacuum evaporation. 60 Layer, and then use atomic layer deposition on C 60 A SnO2 layer is deposited on the layer, and a protective layer 12 of ITO is deposited on the SnO2 layer by magnetron sputtering.

[0119] (3) A carbon electrode 13 layer is prepared on the protective layer 12, and the carbon electrode 13 layer is prepared by the preparation method described in Example 1.

[0120] Application Example 2-10

[0121] The difference between Application Example 2-10 and Application Example 1 is that the carbon electrode layer in step (3) is prepared by the preparation method described in Example 2-10.

[0122] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0123] Application Comparative Example 1

[0124] The difference between this comparative example and application example 1 is that the carbon electrode layer in step (3) is prepared using the preparation method described in comparative example 1.

[0125] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0126] Application Comparative Example 2

[0127] The difference between this comparative example and application example 1 is that the carbon electrode layer in step (3) is prepared using the preparation method described in comparative example 2.

[0128] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0129] Application Comparative Example 3

[0130] The difference between this comparative example and Example 1 is that step (3) is replaced with the following steps:

[0131] Silver paste is poured into one end of the screen, and a scraper is used to apply pressure to the silver paste area of ​​the screen while moving it towards the other end. During the movement, the silver paste is squeezed from the mesh of the patterned area onto the protective layer by the scraper. The thickness of the formed silver paste wet film is controlled to be 30μm. Then, it is placed in a curing chamber for high-temperature curing at 160℃ for 20 minutes to obtain a silver electrode.

[0132] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0133] Performance testing

[0134] The photoelectric performance of the tandem solar cells provided in the above application examples and comparative examples was tested. Specific test parameters included open-circuit voltage (V). oc ), short-circuit current (J) sc Fill factor (FF) and power conversion efficiency (PCE) were measured over a 1 cm² area. 2 The testing instruments include a solar simulator and a digital source meter. The solar simulator measures a light intensity of 100 mW / cm². 2 .

[0135] The test results are shown in Table 1.

[0136] Table 1

[0137]

[0138]

[0139] analyze:

[0140] As shown in the table above, the carbon electrode fabrication method provided by this invention reduces the impact on the device during electrode printing and curing, and significantly reduces the damage of the solvent in the carbon paste to the perovskite layer and other functional layers, resulting in a significant improvement in the efficiency of the subsequently fabricated perovskite solar cells or tandem solar cells. The tandem solar cell fabricated based on this invention can operate normally, with a maximum open-circuit voltage of 1.86V and a maximum short-circuit current of 19.98mA / cm². 2 The photoelectric conversion efficiency reaches up to 24.82%.

[0141] As can be seen from Application Examples 1 and 9-10, if the substrate temperature is controlled at room temperature, the solvent in the carbon paste cannot be completely removed due to the low temperature of the substrate, resulting in a decrease in the short-circuit current of the tandem solar cell and a reduction in the photoelectric conversion efficiency of the cell. If the substrate temperature is controlled at 60°C, the high temperature of the substrate accelerates the penetration of the solvent into the perovskite layer and other functional layers, resulting in a decrease in both the open-circuit voltage and short-circuit current of the tandem solar cell and a reduction in the photoelectric conversion efficiency of the cell.

[0142] As can be seen from Application Example 1 and Application Comparative Example 1, if the wet carbon film is dried directly to obtain the carbon electrode, it needs to be dried at 120°C for at least 15 minutes. This heating process will cause the perovskite and other functional layers to decompose, ultimately resulting in lower device performance.

[0143] As can be seen from Application Example 1 and Application Comparative Example 2, if liquid alkanes are replaced with chloroform, since chloroform is a solvent with a boiling point similar to that of liquid alkanes but compatible with carbon slurry solvents, the addition of chloroform cannot significantly reduce the boiling point of the carbon slurry solvent. Therefore, the solvent cannot be completely removed under low temperature conditions, resulting in the carbon electrode failing to solidify.

[0144] As can be seen from Application Example 1 and Application Comparative Example 3, if a high-temperature cured silver electrode is used instead of a carbon electrode, the temperature and heating time of the curing conditions are higher than those in Application Example 1. Therefore, the decomposition of the perovskite layer is more severe, resulting in lower efficiency.

[0145] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a carbon electrode, characterized in that, The preparation method includes the following steps: A carbon slurry is coated onto a substrate to obtain a wet carbon film, and then liquid alkane is coated onto the wet carbon film to obtain the carbon electrode.

2. The preparation method according to claim 1, characterized in that, The carbon material in the carbon slurry includes any one or a combination of at least two of graphite, carbon black, carbon nanotubes, carbon fibers, or graphene. Preferably, the solvent of the carbon slurry includes any one or a combination of at least two of the following: water, methanol, acrylic resin, diethylene glycol butyl ether, diethylene glycol propyl ether, propylene glycol methyl ether, or terpineol. Preferably, the viscosity of the carbon slurry is 1000-30000 cps; Preferably, the solid content of the carbon slurry is 20-80 wt%.

3. The preparation method according to claim 1 or 2, characterized in that, The carbon paste is coated using screen printing. Preferably, the thickness of the wet carbon film is 10-100 μm.

4. The preparation method according to any one of claims 1-3, characterized in that, The liquid alkane includes any one or a combination of at least two of cyclohexane, cyclopentane, n-hexane, n-pentane, n-heptane, or isooctane, preferably cyclopentane and / or n-pentane; Preferably, the liquid alkane is coated by screen printing.

5. The preparation method according to any one of claims 1-4, characterized in that, During the liquid alkane coating process, the temperature of the substrate is controlled at 30-50℃.

6. A carbon electrode, characterized in that, The carbon electrode is prepared using the preparation method described in any one of claims 1-5.

7. A perovskite solar cell, characterized in that, The perovskite solar cell includes a conductive substrate, a perovskite light-absorbing layer, an electron transport layer, and a carbon electrode as described in claim 6, all stacked together.

8. A tandem solar cell, characterized in that, The stacked solar cell includes a crystalline silicon base cell, a tunneling layer, a first charge transport layer, a perovskite light-absorbing layer, a second charge transport layer, and a carbon electrode as described in claim 6, all stacked together.

9. The tandem solar cell according to claim 8, characterized in that, The crystalline silicon bottom cell includes a stacked metal back electrode, an ITO layer, a p-type amorphous silicon layer, a first amorphous silicon intrinsic layer, a monocrystalline silicon layer, a second amorphous silicon intrinsic layer, and an n-type amorphous silicon layer, wherein the n-type amorphous silicon layer is close to the tunneling layer. Preferably, the tunneling layer includes an ITO layer or an IZO layer; Preferably, the thickness of the tunneling layer is 5-30 nm.

10. The tandem solar cell according to claim 8 or 9, characterized in that, The charges transported by the first charge transport layer and the second charge transport layer are of opposite electrical nature; Preferably, the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer; Preferably, the hole transport layer comprises a monomolecular self-assembled layer and / or a nickel oxide layer; Preferably, the perovskite light-absorbing layer is a wide-bandgap perovskite light-absorbing layer with a thickness of 300-1000 nm.

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