A conductive paste and its preparation method and application in porous back electrode

Abstract

The present invention relates to a conductive paste and a preparation method thereof and an application in a porous back electrode, belonging to the technical field of electrode preparation of photovoltaic devices. The conductive paste in the present invention includes conductive medium particles, a pore former, a binder and a solvent; the conductive medium particles include at least one of metal nitrides, metal carbides, metal borides, metal oxides and metal silicides. Among them, the conductive medium particles, as the main component of the porous back electrode, have high conductivity and high temperature stability. The conductive paste of the present invention includes one or more of metal nitrides, metal carbides, metal borides, metal oxides and metal silicides, thereby increasing the overall conductivity of the porous back electrode, making the carrier transmission on the porous back electrode less hindered, thereby improving the performance of the perovskite solar cell.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode preparation of photovoltaic devices, and more specifically, to a conductive paste and a preparation method thereof and an application in a porous back electrode, and in particular to a preparation method for a high-performance porous back electrode of a mesoscopic perovskite solar cell. Background Art

[0002] In the past decade, perovskite solar cells have developed rapidly, and their photoelectric conversion efficiency has increased from 3.8% to 25.7% in just a few years. Perovskite solar cells are third-generation thin-film solar photovoltaic cells that use semiconductor materials with similar crystal structures to perovskites as light-absorbing materials. They have outstanding advantages such as high photoelectric conversion efficiency, solution preparation, and low cost. They have broad application prospects and are expected to trigger an energy revolution in related fields. The electrode of a perovskite solar cell is one of the core parts of the device and greatly affects the performance of the device.

[0003] There are many types of electrode materials, and metals are currently the most widely used electrode materials, including gold, silver, etc. The high conductivity of metal electrodes is conducive to higher efficiency of devices. However, due to the high price of precious metals and the complex deposition method, it is not conducive to the production of large-area devices. In addition, metal electrodes are not stable enough, and metal clusters or ions can easily diffuse into the perovskite absorption layer, resulting in a decrease in device performance. These unfavorable factors will hinder the commercialization of perovskite solar cells. Carbon materials such as graphite, carbon black, carbon nanotubes, and graphene can solve these problems well as electrode materials. They have the advantages of low cost, good stability, good conductivity, and work function close to that of gold electrodes (4.8eV and 5.1eV, respectively). In addition, carbon electrode materials are hydrophobic, which is beneficial to block the penetration of water into perovskite, thereby improving the stability of the device.

[0004] The high conductivity of the porous back electrode in the mesoscopic perovskite solar cell is the basis for ensuring the excellent performance of the device. The large resistance of the electrode will hinder the transmission of carriers, thereby limiting the performance of the device. Graphite is widely used in porous back electrodes because of its high conductivity. In addition, the addition of a small amount of carbon black can build a conductive channel between graphite sheets, which is beneficial to the improvement of the overall conductivity of the porous back electrode. At the same time, the addition of carbon black can increase the viscosity of the electrode slurry and improve the quality of screen printing. However, the conductivity of the back electrode based on carbon black and graphite is far inferior to that of the metal electrode. Among them, carbon black is an amorphous carbon material with a concentric circle structure of graphite layer stacking, so its conductivity is very poor, not as good as graphite with directional arrangement and orientation. Therefore, the use of more suitable conductive materials to replace the carbon black in the traditional porous back electrode is expected to further improve the conductivity of the porous back electrode, which is beneficial to improve the performance of mesoscopic perovskite solar cells. Summary of the invention

[0005] In view of the defects of the prior art and the need for improvement, the present invention provides a conductive slurry, a preparation method thereof, and an application in a porous back electrode. In the present invention, the electrode slurry includes the following components: conductive medium particles, a binder, a pore former, and a solvent, wherein the conductive medium particles include at least one of metal nitrides, metal carbides, metal borides, metal oxides, and metal silicides. By adding a highly conductive and high temperature resistant material as a conductive medium, the overall conductivity of the porous back electrode can be increased, so that the carrier transmission on the porous back electrode is less hindered, thereby improving the performance of the mesoscopic perovskite solar cell. This solves the technical problems of the poor conductivity of the porous back electrode and the poor performance of the mesoscopic perovskite solar cell in the prior art.

[0006] According to a first aspect of the present invention, there is provided a conductive paste, comprising conductive medium particles, a binder and a solvent; the boiling point of the solvent is greater than 100° C.; the conductive medium particles comprise a metal compound, and the metal compound is at least one of a metal nitride, a metal carbide, a metal boride, a metal oxide and a metal silicide;

[0007] When the adhesive has a pore-forming effect, the adhesive also acts as a pore-forming agent;

[0008] When the adhesive does not have a pore-forming effect, the conductive paste further includes a pore-forming agent.

[0009] Preferably, the metal nitride is at least one of titanium nitride, niobium nitride, zirconium nitride, hafnium nitride, tantalum nitride and vanadium nitride;

[0010] The metal carbide is at least one of titanium carbide, niobium carbide, vanadium carbide, tantalum carbide, zirconium carbide, chromium carbide and tungsten carbide;

[0011] The metal boride is at least one of titanium diboride, zirconium diboride, niobium diboride, hafnium diboride, rhodium diboride, tantalum diboride, molybdenum diboride, lanthanum hexaboride, cesium hexaboride, praseodymium hexaboride, samarium hexaboride, gadolinium hexaboride and dysprosium hexaboride;

[0012] The metal oxide is at least one of rubidium dioxide, iridium dioxide and lead dioxide;

[0013] The metal silicide is at least one of titanium disilicide and cobalt disilicide.

[0014] Preferably, the conductive medium particles further include graphite, carbon black, graphene, carbon nanotubes, activated carbon or doped semiconductors;

[0015] Preferably, the doped semiconductor is fluorine-doped tin oxide, tin-doped indium oxide, aluminum-doped zinc oxide or antimony-doped tin oxide.

[0016] Preferably, in the conductive paste, the ratio of the mass of the conductive medium particles to the sum of the mass of the binder and the pore-forming agent is (5-10):(1-3); the mass proportion of the metal compound in the conductive medium particles is 20%-40%.

[0017] Preferably, the binder is one or more of zirconium oxide, cellulose, polyethylene glycol, starch and polyvinyl pyrrolidone;

[0018] The pore-forming agent is one or more of cellulose, polystyrene and polyvinyl pyrrolidone.

[0019] The solvent is one or more of n-butanol, terpineol and ethylene glycol.

[0020] According to another aspect of the present invention, a method for preparing any one of the conductive pastes is provided, wherein the conductive medium particles, the binder and the solvent are mixed, or the conductive medium particles, the binder, the pore-forming agent and the solvent are mixed, the boiling point of the solvent is greater than 100° C., and a low boiling point solvent is added, wherein the low boiling point solvent is one or more of ethanol and isopropanol, and after sufficient mixing, the low boiling point solvent is removed by rotary evaporation to obtain the electrode slurry.

[0021] According to another aspect of the present invention, there is provided a use of any one of the conductive pastes for preparing a porous back electrode;

[0022] Preferably, the back electrode is a porous back electrode of a mesoscopic perovskite solar cell.

[0023] Preferably, the application is specifically: coating the electrode slurry on a substrate by screen printing or doctor blade coating, and heating to remove the binder, pore former and solvent, so as to obtain a porous back electrode.

[0024] According to another aspect of the present invention, a porous back electrode is provided, which is obtained by the application.

[0025] According to another aspect of the present invention, a mesoscopic perovskite solar cell is provided, comprising the porous back electrode.

[0026] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0027] (1) The present invention provides a method for preparing a highly conductive slurry and applying it to a porous back electrode. The carbon black with poor conductivity in the porous back electrode of a mesoscopic perovskite solar cell is replaced with a high-temperature resistant highly conductive medium, including metal nitrides, metal carbides, metal borides, metal oxides, and metal silicides, which can effectively improve the overall conductivity of the porous back electrode, reduce the transmission barrier of carriers on the electrode, and help improve the performance of the mesoscopic perovskite solar cell.

[0028] (2) Existing electrode conductive pastes contain metal particles, which have good conductivity. However, metal conductive medium particles will be oxidized when calcined at high temperature in air, which is not conducive to the performance of printable mesoscopic perovskite solar cells. The conductive paste of the present invention uses non-metallic conductive medium particles, which include at least one of metal nitride, metal carbide, metal boride, metal oxide and metal silicide. They have the characteristics of high temperature stability and high conductivity, and are suitable for preparing high-temperature porous back electrodes in printable mesoscopic perovskite solar cells.

[0029] (3) The present invention uses TiN to replace CB in the porous back electrode, which can reduce the resistivity of the electrode from 0.0198Ω·cm to 0.0098Ω·cm, and the resistivity is reduced by 50%.

[0030] (4) The present invention uses NbN to replace CB in the porous back electrode, which can reduce the resistivity of the electrode from 0.0198Ω·cm to 0.014Ω·cm, a 29% reduction in resistivity.

[0031] (5) The present invention uses TaC to replace CB in the porous back electrode, which can reduce the resistivity of the electrode from 0.0198Ω·cm to 0.0088Ω·cm, a reduction of 56%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of a mesoscopic perovskite solar cell based on a high-performance porous back electrode provided in an embodiment of the present invention.

[0033] Figure 2 It is a statistical graph of test results of the resistivity of the high-performance porous back electrode provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] The present invention discloses a conductive paste, comprising conductive medium particles, a pore former, a binder and a solvent; the conductive medium particles comprise a metal compound, and the metal compound is at least one of metal nitride, metal carbide, metal boride, metal oxide and metal silicide.

[0036] In some embodiments, the metal nitride is at least one of titanium nitride, niobium nitride, zirconium nitride, hafnium nitride, tantalum nitride and vanadium nitride;

[0037] In some embodiments, the metal carbide is at least one of titanium carbide, niobium carbide, vanadium carbide, tantalum carbide, zirconium carbide, chromium carbide and tungsten carbide.

[0038] In some embodiments, the metal boride is at least one of titanium diboride, zirconium diboride, niobium diboride, hafnium diboride, rhodium diboride, tantalum diboride, molybdenum diboride, lanthanum hexaboride, cesium hexaboride, praseodymium hexaboride, samarium hexaboride, gadolinium hexaboride and dysprosium hexaboride.

[0039] In some embodiments, the metal oxide is at least one of rubidium dioxide, iridium dioxide and lead dioxide.

[0040] In some embodiments, the metal silicide is at least one of titanium disilicide and cobalt disilicide.

[0041] In some embodiments, the conductive medium particles include graphite, carbon black, graphene, carbon nanotubes, activated carbon or doped semiconductors;

[0042] Preferably, the doped semiconductor is fluorine-doped tin oxide, tin-doped indium oxide, aluminum-doped zinc oxide or antimony-doped tin oxide.

[0043] In some embodiments, in the conductive paste, the metal compound accounts for 5-30% by mass, the remaining conductive medium particles account for 5-30% by mass, the binder accounts for 1-5% by mass, the pore former accounts for 1-10% by mass, and the rest is solvent.

[0044] The preparation method of the electrode slurry of the present invention comprises the following steps: weighing the conductive medium particles, the binder, the pore former and the solvent according to the proportion; adding an appropriate amount of a low boiling point solvent, including one or more of ethanol and isopropanol; then ball milling for 24-80 hours at a rotation speed of 300-350 r / min to mix and disperse evenly; and then removing the ethanol by rotary evaporation to obtain the electrode slurry.

[0045] Preferably, the electrode slurry can be used to prepare a porous back electrode of a mesoscopic perovskite solar cell.

[0046] The present invention provides a mesoscopic perovskite solar cell, which has the structure of: a dense hole blocking layer, a mesoporous electron transport layer, a mesoporous spacer layer, a porous back electrode and a perovskite filled in the mesoporous electron transport layer are sequentially arranged on a transparent conductive substrate. Figure 1 It is a schematic diagram of the structure of a mesoscopic perovskite solar cell based on a high-performance porous back electrode provided in an embodiment of the present invention.

[0047] In some embodiments, the method for preparing the mesoscopic perovskite solar cell comprises the following steps:

[0048] (1) Spraying a thin dense layer of TiO2 on a transparent conductive glass substrate as a barrier layer;

[0049] (2) screen printing TiO2 slurry on the TiO2 dense layer and annealing at 500° C. to form a TiO2 mesoporous electron transport layer;

[0050] (3) screen printing ZrO2 slurry on the TiO2 mesoporous layer and drying it at 75° C. to form a ZrO2 spacer layer;

[0051] (4) screen printing the electrode slurry obtained by the preparation method on the ZrO2 spacer layer, and then annealing at 400°C for 40 minutes to obtain a porous back electrode;

[0052] (5) The perovskite precursor solution is dripped into the porous back electrode surface and annealed and crystallized to finally obtain a perovskite solar cell.

[0053] Example 1

[0054] The porous back electrode slurry of the perovskite solar cell of this embodiment includes the following components:

[0055] Graphite: 6.5g;

[0056] Titanium nitride: 1g;

[0057] Zirconium oxide: 1.25g;

[0058] Ethyl cellulose: 1.2 g;

[0059] Terpineol: 23g;

[0060] The preparation method of the porous back electrode slurry of the perovskite solar cell of this embodiment includes the following steps: weighing a certain amount of graphite (PG: pyrolytic graphite), titanium nitride (TiN), zirconium oxide (ZrO2), ethyl cellulose, pinene alcohol, and an appropriate amount of ethanol, and placing these materials in a clean zirconium oxide ball mill, ball milling at a speed of 300r / min for 48h, then taking them out, and then rotary evaporating to remove the ethanol to obtain a gray-black porous back electrode slurry.

[0061] Then, a porous back electrode was prepared on the substrate by screen printing. After printing, the substrate was dried on a 75°C hot plate, and then transferred to another hot plate for program annealing. Specifically, the temperature of the hot plate was gradually increased from room temperature to 400°C (heating rate was 10°C / min), and then kept at 400°C for 40 minutes and then cooled naturally to obtain a porous back electrode.

[0062] Preferably, when the substrate is glass, the porous back electrode can be used to test its resistivity; when the substrate is mesoporous ZrO2, the porous back electrode is used to prepare perovskite solar cells.

[0063] The perovskite solar cell of this embodiment uses the back electrode slurry obtained by the method to prepare a porous back electrode, and the specific steps include:

[0064] (1) Spraying a thin dense layer of TiO2 on a fluorine-doped tin oxide glass substrate;

[0065] (2) screen printing TiO2 slurry on the TiO2 dense layer and annealing at 500° C. to form a TiO2 mesoporous layer;

[0066] (3) screen printing ZrO2 slurry on the TiO2 mesoporous layer and drying it at 75° C. to form a ZrO2 spacer layer;

[0067] (4) screen printing the back electrode slurry obtained by the preparation method on the ZrO2 spacer layer, and then annealing at 400°C for 40 minutes to obtain a porous back electrode;

[0068] (5) A methylamine formamidinium lead iodide perovskite precursor solution is dripped onto the surface of the porous back electrode and annealed and crystallized to finally obtain a perovskite solar cell.

[0069] Example 2

[0070] The porous back electrode slurry of the perovskite solar cell of this embodiment includes the following components:

[0071] Graphite: 6.5g;

[0072] Niobium nitride: 1g;

[0073] Zirconium oxide: 1.25g;

[0074] Ethyl cellulose: 1.2 g;

[0075] Terpineol: 23g;

[0076] The preparation method of the porous back electrode slurry of the perovskite solar cell of this embodiment includes the following steps: weighing a certain amount of graphite (PG: pyrolytic graphite), niobium nitride (NbN), zirconium oxide (ZrO2), ethyl cellulose, pinene alcohol, and an appropriate amount of ethanol, and placing these materials in a clean zirconium oxide ball mill, ball milling at a speed of 300r / min for 48h, then taking them out, and then rotary evaporating to remove the ethanol to obtain a gray-black porous back electrode slurry.

[0077] Then, a porous back electrode was prepared on the substrate by screen printing. After printing, the substrate was placed on a 75°C hot plate for drying, and then the substrate was transferred to another hot plate for program annealing. Specifically, the temperature of the hot plate was gradually increased from room temperature to 400°C (heating rate was 10°C / min), and then kept at 400°C for 40 minutes and then cooled naturally to obtain a porous back electrode.

[0078] Preferably, when the substrate is glass, the back electrode can be used to test its resistivity; when the substrate is mesoporous ZrO2, the back electrode is used to prepare perovskite solar cells.

[0079] The perovskite solar cell of this embodiment uses the back electrode slurry obtained by the method to prepare a porous back electrode, and the specific steps include:

[0080] (1) Spraying a thin dense layer of TiO2 on a fluorine-doped tin oxide glass substrate;

[0081] (2) screen printing TiO2 slurry on the TiO2 dense layer and annealing at 500° C. to form a TiO2 mesoporous layer;

[0082] (3) screen printing ZrO2 slurry on the TiO2 mesoporous layer and drying it at 75° C. to form a ZrO2 spacer layer;

[0083] (4) screen printing the back electrode slurry obtained by the preparation method on the ZrO2 spacer layer, and then annealing at 400°C for 40 minutes to obtain a porous back electrode;

[0084] (5) A methylamine formamidinium lead iodide perovskite precursor solution is dripped onto the surface of the porous back electrode and annealed and crystallized to finally obtain a perovskite solar cell.

[0085] Example 3

[0086] The porous back electrode slurry of the perovskite solar cell of this embodiment includes the following components:

[0087] Graphite: 6.5g;

[0088] Tantalum carbide: 1g;

[0089] Zirconium oxide: 1.25g;

[0090] Ethyl cellulose: 1.2 g;

[0091] Terpineol: 23g;

[0092] The preparation method of the porous back electrode slurry of the perovskite solar cell of this embodiment includes the following steps: weighing a certain amount of graphite (PG: pyrolytic graphite), tantalum carbide (TaC), zirconium oxide (ZrO2), ethyl cellulose, pinene alcohol, and an appropriate amount of ethanol, and placing these materials in a clean zirconium oxide ball mill, ball milling at a speed of 300r / min for 48h, then taking them out, and then rotary evaporating to remove the ethanol to obtain a gray-black porous back electrode slurry.

[0093] Then, a porous back electrode was prepared on the substrate by screen printing. After printing, the substrate was placed on a 75°C hot plate for drying, and then the substrate was transferred to another hot plate for program annealing. Specifically, the temperature of the hot plate was gradually increased from room temperature to 400°C (heating rate was 10°C / min), and then kept at 400°C for 40 minutes and then cooled naturally to obtain a porous back electrode.

[0094] Preferably, when the substrate is glass, the back electrode can be used to test its resistivity; when the substrate is mesoporous ZrO2, the back electrode is used to prepare perovskite solar cells.

[0095] The perovskite solar cell of this embodiment uses the back electrode slurry obtained by the method to prepare a porous back electrode, and the specific steps include:

[0096] (1) Spraying a thin dense layer of TiO2 on the FTO glass substrate;

[0097] (2) screen printing TiO2 slurry on the TiO2 dense layer and annealing at 500° C. to form a TiO2 mesoporous layer;

[0098] (3) screen printing ZrO2 slurry on the TiO2 mesoporous layer and drying it at 75° C. to form a ZrO2 spacer layer;

[0099] (4) screen printing the back electrode slurry obtained by the preparation method on the ZrO2 spacer layer, and then annealing at 400°C for 40 minutes to obtain a porous back electrode;

[0100] (5) A methylamine formamidinium lead iodide perovskite precursor solution is dripped onto the surface of the porous back electrode and annealed and crystallized to finally obtain a perovskite solar cell.

[0101] Comparative Example 1

[0102] The porous back electrode slurry of the perovskite solar cell of this comparative example includes the following components:

[0103] Graphite: 6.5g;

[0104] Carbon black: 2g;

[0105] Zirconium oxide: 1.25g;

[0106] Ethyl cellulose: 1.2 g;

[0107] Terpineol: 23g;

[0108] The preparation method of the perovskite solar cell and the preparation method of the porous back electrode of this comparative example are exactly the same as those of Examples 1, 2, and 3, with the only difference being that the conductive medium of the porous back electrode adopts the components of a traditional carbon back electrode, including carbon black and graphite.

[0109] Comparative Example 2

[0110] The porous back electrode slurry of the perovskite solar cell of this comparative example includes the following components:

[0111] Graphite: 8.5g;

[0112] Zirconium oxide: 1.25g;

[0113] Ethyl cellulose: 1.2 g;

[0114] Terpineol: 23g;

[0115] The preparation method of the perovskite solar cell and the preparation method of the porous back electrode of this comparative example are exactly the same as those of Examples 1, 2, and 3, with the only difference being that the conductive medium of the porous back electrode only includes graphite.

[0116] Test Example

[0117] In order to verify the technical effect of the high-performance porous back electrode described in the present invention, the resistivity of the porous back electrodes prepared with different back electrode slurries was jointly tested by four-probe and step profiler.

[0118] Experimental results refer to Figure 2As shown in Table 1, the resistivity of the porous back electrode based on CB and PG is 0.0198Ω·cm, and the resistivity of the porous back electrode based on pure PG (equivalent PG replacing CB) is 0.0092Ω·cm, indicating that replacing CB with PG can reduce the resistance of the porous back electrode and increase its conductivity. This is because pyrolytic graphite is composed of stacked graphite layers composed of hexagonal rings of carbon, which is highly oriented, making the lateral conductivity of graphite very good, comparable to that of metals. However, if only graphite is used as a conductive medium particle, the printing performance of the carbon slurry will be poor, and the carbon film will be loose and easy to peel off, thus affecting the device performance. Carbon black has an amorphous structure, a low degree of graphitization, and a concentric circle orientation of graphite layers. Therefore, the aggregates of carbon black appear as strings of nanoparticles, making its conductivity far inferior to that of pyrolytic graphite. However, a highly conductive pure PG porous electrode is obtained by the method of the present invention, which means that the conductivity of the porous back electrode can be improved by replacing the CB with poor conductivity in the traditional carbon back electrode with a high-temperature resistant high-conductivity material through this method, which is conducive to the preparation of high-performance perovskite solar cells.

[0119] See also Figure 2 The resistivity of the porous back electrodes based on TiN and PG, NbN and PG, TaC and PG are 0.00098Ω·cm, 0.014Ω·cm, and 0.0088Ω·cm, respectively, while the resistivity of the traditional porous carbon back electrode based on PG and CB components is 0.0198Ω·cm, indicating that replacing the CB in the traditional porous back electrode with conductive media such as TiN, NbN, and TaC can improve the conductivity of the porous back electrode. In addition, the conductivity of the porous back electrodes based on TiN and PG, TaC and PG is comparable to that based on pure graphite electrodes, so they may have better performance.

[0120] Table 1 Resistivity of different porous back electrodes

[0121]

[0122]

[0123] The back electrode material replacing CB in the present invention is not limited to PG, TiN, NbN, TaC, and other high-temperature stable and highly conductive media can be used, including metal nitrides, carbides, borides, oxides, and silicides. Specifically including: titanium nitride, niobium nitride, zirconium nitride, hafnium nitride, tantalum nitride, vanadium nitride, titanium carbide, niobium carbide, vanadium carbide, tantalum carbide, zirconium carbide, chromium carbide, tungsten carbide, titanium diboride, zirconium diboride, niobium diboride, hafnium diboride, rhodium diboride, tantalum diboride, molybdenum diboride, lanthanum hexaboride, cesium hexaboride, praseodymium hexaboride, samarium hexaboride, gadolinium hexaboride, dysprosium hexaboride, rubidium dioxide, iridium dioxide, lead dioxide, titanium disilicide, titanium disilicide, and cobalt disilicide.

[0124] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of conductive paste for preparing porous back electrode, characterized in that: The conductive paste comprises conductive medium particles, a binder, a pore former and a solvent; the boiling point of the solvent is greater than 100° C.; the binder is zirconium oxide; the conductive medium particles comprise a metal compound, and the metal compound is at least one of metal nitride, metal carbide, metal boride, metal oxide and metal silicide; The metal nitride is at least one of titanium nitride, niobium nitride, zirconium nitride, hafnium nitride, tantalum nitride and vanadium nitride; The metal carbide is at least one of titanium carbide, niobium carbide, vanadium carbide, tantalum carbide, zirconium carbide, chromium carbide and tungsten carbide; The metal boride is at least one of titanium diboride, zirconium diboride, niobium diboride, hafnium diboride, rhodium diboride, tantalum diboride, molybdenum diboride, lanthanum hexaboride, cesium hexaboride, praseodymium hexaboride, samarium hexaboride, gadolinium hexaboride and dysprosium hexaboride; The metal oxide is at least one of rubidium dioxide, iridium dioxide and lead dioxide; The metal silicide is at least one of titanium disilicide and cobalt disilicide; The ratio of the mass of the conductive medium particles to the sum of the mass of the binder and the pore-forming agent is (5-10): (1-3); the mass proportion of the metal compound in the conductive medium particles is 20%-40%; The application is specifically as follows: screen printing the conductive paste on the spacer layer, and heating to remove the binder, pore former and solvent, so as to obtain a porous back electrode.

2. The use according to claim 1, characterized in that The back electrode is a porous back electrode of a mesoscopic perovskite solar cell.

3. The use according to claim 1, characterized in that The conductive medium particles also include graphite, carbon black, graphene, carbon nanotubes, activated carbon or doped semiconductors.

4. The use according to claim 3, characterized in that The doped semiconductor is fluorine-doped tin oxide, tin-doped indium oxide, aluminum-doped zinc oxide or antimony-doped tin oxide.

5. The use according to claim 1, characterized in that The pore-forming agent is one or more of cellulose, polystyrene and polyvinyl pyrrolidone; The solvent is one or more of n-butanol, terpineol and ethylene glycol.

6. The use according to claim 1, characterized in that After the conductive medium particles, binder, pore former and solvent are mixed, the boiling point of the solvent is greater than 100° C., a low boiling point solvent is added, and the low boiling point solvent is one or more of ethanol and isopropanol. After fully mixing, the low boiling point solvent is removed by rotary evaporation to obtain the electrode slurry.

7. A porous back electrode, characterized in that: Obtained by applying any one of claims 1 to 6.

8. A mesoscopic perovskite solar cell, characterized in that: Comprising the porous back electrode as claimed in claim 7.

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