Solar cell and preparation method thereof, photovoltaic cell module and photovoltaic cell system

Abstract

The invention discloses a solar cell and a preparation method thereof, a photovoltaic cell module and a photovoltaic cell system, relates to the technical field of photovoltaic solar cells, and aims to solve the problem of poor charge injection effect between an absorption layer and a hole transport layer in the photovoltaic solar cell. The solar cell comprises an absorption layer, a first hole transport layer and a second hole transport layer. The material of the absorption layer comprises a perovskite material. The second hole transport layer is located on the side, away from the absorption layer, of the first hole transport layer and makes contact with the first hole transport layer. The material of the second hole transport energy layer comprises nickel oxide. Materials of the first hole transport layer comprise a self-assembly material and a first functional material. The first functional material includes an oxyacid group.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic solar cells, and in particular to a solar cell and a preparation method thereof, a photovoltaic cell assembly and a photovoltaic cell system. Background Art

[0002] In solar cells, due to the contact interface defects between the absorption layer and the hole transport layer, carriers accumulate and pile up at the interface of the solar cell, resulting in poor charge transport, affecting the charge injection effect, and affecting the working stability of the solar cell, as well as severely limiting the open circuit voltage (Voc) and fill factor (FF) of the solar cell. Summary of the invention

[0003] The purpose of the present application is to provide a solar cell and a preparation method thereof, a photovoltaic cell assembly and a photovoltaic cell system, aiming to solve the problem of poor charge injection effect between the absorption layer and the hole transport layer in the solar cell.

[0004] In order to achieve the above objectives, this application adopts the following technical solutions:

[0005] In a first aspect, the present application provides a solar cell, which includes an absorption layer, a first hole transport layer, and a second hole transport layer.

[0006] The material of the absorption layer includes a perovskite material. The second hole transport layer is located on a side of the first hole transport layer away from the absorption layer and is in contact with the first hole transport layer. The material of the second hole transport layer includes nickel oxide.

[0007] The material of the first hole transport layer includes: a self-assembly material and a first functional material. The first functional material includes an oxygen-containing acid group.

[0008] In the solar cell provided in the embodiment of the present application, the absorption layer is responsible for absorbing sunlight and generating photogenerated carriers (electrons and holes). The first hole transport layer optimizes the charge transfer path and improves the charge transfer efficiency. The second hole transport layer promotes the transmission of photogenerated holes from the absorption layer to the electrode. Nickel oxide improves the photoelectric conversion efficiency and improves the stability of the solar cell.

[0009] The oxygen-containing acid groups in the first functional material in the first hole transport layer can react with the hydroxyl groups to form chemical bonds, thereby reducing the hydroxyl content in the nickel oxide, passivating the contact interface defects between the absorption layer and the hole transport layer, reducing the non-radiative recombination caused by the defects, and enhancing the interface bonding force and charge transfer efficiency between the first hole transport layer and the second hole transport layer, thereby improving the charge injection effect between the absorption layer and the hole transport layer and improving the charge transfer efficiency. At the same time, the stability and durability of the second hole transport layer can also be enhanced, thereby improving the overall performance of the solar cell.

[0010] In addition, the self-assembled material and the first functional material work together, the self-assembled material optimizes the charge transfer path and improves the charge transfer efficiency, the first functional material reduces the hydroxyl group in the nickel oxide on the second hole transport layer, passivates the contact interface defects between the absorption layer and the hole transport layer, improves the charge injection effect between the absorption layer and the hole transport layer, reduces the non-radiative recombination caused by the defects, improves the carrier extraction efficiency, and jointly improves the efficiency and stability of the solar cell 100.

[0011] In some embodiments, the oxoacid group includes at least one of a carboxyl group, a boronic acid group, or a phosphonic acid group.

[0012] In some embodiments, the first functional material further includes: an amino group.

[0013] In some embodiments, the first functional material includes a linking group, and the linking group includes at least one of a phenyl group and a C1-C6 alkylene group.

[0014] In some embodiments, the first functional material includes at least one of p-aminobenzoic acid, glycine, and 4-aminobutyric acid.

[0015] In some embodiments, the mass ratio of the self-assembly material to the first functional material is in the range of 0.5:(0.05-3).

[0016] In some embodiments, the material of the first hole transport layer further includes: a second functional material. The second functional material includes: at least one of alkali metal halide, alkaline earth metal halide and ammonium halide.

[0017] In some embodiments, the second functional material further includes fluorine element.

[0018] In some embodiments, the second functional material includes at least one of potassium fluoride, sodium fluoride, and ammonium fluoride.

[0019] In some embodiments, the mass ratio of the self-assembly material to the second functional material is in the range of 0.5:(0.05-3).

[0020] In some embodiments, the self-assembled material includes at least one of (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, and [2-(9H-carbazol-9-yl)ethyl]phosphonic acid.

[0021] In some embodiments, the thickness of the first hole transport layer is in the range of 5 nm to 10 nm.

[0022] In some embodiments, the absorber layer has a thickness ranging from 550 nm to 600 nm.

[0023] In some embodiments, the second hole transport layer has a thickness ranging from 10 nm to 20 nm.

[0024] In a second aspect, the present application provides a method for preparing a solar cell, comprising:

[0025] A second hole transport layer is formed; the material of the second hole transport layer includes nickel oxide.

[0026] A first hole transport layer is formed on one side of the second hole transport layer; the second hole transport layer is in contact with the first hole transport layer; the material of the first hole transport layer includes: a self-assembly material and a first functional material. The first functional material includes an oxygen-containing acid group.

[0027] An absorption layer is formed on a side of the first hole transport layer away from the second hole transport layer. The material of the absorption layer includes a perovskite material.

[0028] In some embodiments, forming a first hole transport layer on one side of the second hole transport layer includes:

[0029] A first solution is coated on one side of the second hole transport layer and annealed, wherein the first solution includes a first functional material.

[0030] In some embodiments, the concentration of the first functional material in the first solution is in the range of 0.05 mg / mL to 3 mg / mL.

[0031] In some embodiments, the first solution further includes a second functional material; the concentration of the second functional material in the first solution is in the range of 0.05 mg / mL to 3 mg / mL.

[0032] In some embodiments, the second functional material includes at least one of an alkali metal halide, an alkaline earth metal halide, and an ammonium halide.

[0033] In some embodiments, the temperature of the annealing process is in a range of 90°C to 110°C.

[0034] In some embodiments, the annealing treatment time ranges from 8 min to 12 min.

[0035] In a third aspect, the present application provides a photovoltaic cell assembly, comprising: a solar cell as described in any one of the above embodiments.

[0036] It can be understood that the beneficial effects that can be achieved by the photovoltaic cell assembly provided in the above embodiments of the present application can refer to the beneficial effects of the solar cell mentioned above, and will not be repeated here.

[0037] In a fourth aspect, the present application provides a photovoltaic cell system, comprising: an inverter and a photovoltaic cell assembly as in the above embodiment, wherein the inverter is electrically connected to the photovoltaic cell assembly.

[0038] It can be understood that the beneficial effects that can be achieved by the photovoltaic cell system provided in the above embodiments of the present application can refer to the beneficial effects of the solar cell mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a schematic diagram of the structure of a solar cell in an embodiment of the present application;

[0041] Figure 2 This is a forward and reverse scan curve diagram of the current density-voltage test of the solar cell of Example 1 of the present application;

[0042] Figure 3 This is a current density-voltage curve test diagram of the solar cell of Comparative Example 1 and Example 1 of the present application;

[0043] Figure 4 This is a test diagram of the external quantum efficiency of the solar cells of Comparative Example 1 and Example 1 of the present application;

[0044] Figure 5 Schematic diagram of the function of materials used in the hole transport layer 20 in some embodiments of the present application;

[0045] Figure 6 This is a flow chart of a method for preparing a solar cell in some embodiments of the present application.

[0046] Reference numerals: 100 - solar cell, 10 - substrate, 20 - hole transport layer, 21 - first hole transport layer, 22 - second hole transport layer, 30 - absorption layer, 40 - electron transport layer, 50 - hole blocking layer and 60 - electrode. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "inside", "outside", etc. indicate directions or positional relationships based on the directions or relative positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. Unless otherwise specified, the above-mentioned directional description can be flexibly set in the process of actual application under the condition that the relative positional relationship shown in the accompanying drawings is met.

[0049] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0050] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. It can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In the present application, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, article or device including the element.

[0052] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0053] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0054] The embodiment of the present application provides a photovoltaic cell system, which includes a photovoltaic cell assembly and an inverter, wherein the inverter is electrically connected to the photovoltaic cell assembly.

[0055] In a photovoltaic cell system, the direct current generated by the photovoltaic cell modules is transmitted to the inverter through wires, and the inverter then converts it into alternating current for use by the power user.

[0056] The embodiment of the present application provides a photovoltaic cell assembly, including: a solar cell.

[0057] The solar cell may be a perovskite solar cell.

[0058] Perovskite solar cells are solar cells that use perovskite-type organic metal halide semiconductors as light-absorbing materials and have the advantages of high efficiency and low cost.

[0059] like Figure 1 As shown, the solar cell 100 is composed of a transparent conductive substrate 10, a hole transport layer 20, an absorption layer 30 and an electrode 60. The absorption layer 30 is the core of the solar cell and is responsible for absorbing sunlight and generating photogenerated electrons and holes.

[0060] In some examples, the solar cell 100 further includes an electron transport layer 40 and a hole blocking layer 50 located between the absorption layer 30 and the electrode 60 , and the hole blocking layer 50 is closer to the electrode 60 than the electron transport layer 40 .

[0061] For example, the material of the electron transport layer 40 may be C60.

[0062] For example, the material of the hole blocking layer 50 may be 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

[0063] Illustratively, the electrode 60 may be silver.

[0064] It can be understood that the absorption layer 30 is composed of a perovskite material, which has excellent light absorption performance and charge separation ability. When sunlight irradiates the absorption layer 30, photons are absorbed and excite electron-hole pairs, which are separated in the absorption layer 30 to form free electrons and holes. Subsequently, the free electrons and holes are respectively guided out by the electron transport layer and the hole transport layer, and form a current in the external circuit, thereby converting light energy into electrical energy.

[0065] The hole transport layer 20 helps holes to be transported from the absorption layer 30 to an external circuit, thereby improving the photoelectric conversion efficiency of the solar cell 100 . The performance of the hole transport material directly affects the stability and efficiency of the solar cell 100 .

[0066] In the solar cell 100, due to the contact interface defects between the absorption layer 30 and the hole transport layer 20, carriers will accumulate and pile up at the interface of the solar cell, resulting in poor charge transport, affecting the charge injection effect, and affecting the working stability of the solar cell 100, as well as severely limiting the open circuit voltage (Voc) and fill factor (FF) of the solar cell 100.

[0067] Based on this, an embodiment of the present application provides a solar cell 100. Figure 1 As shown, the solar cell 100 includes: an absorption layer 30 , a first hole transport layer 21 and a second hole transport layer 22 .

[0068] The material of the absorption layer 30 includes a perovskite material. The second hole transport layer 22 is located on a side of the first hole transport layer 21 away from the absorption layer and contacts the first hole transport layer 21. The material of the second hole transport layer 22 includes nickel oxide and hydroxyl groups in nickel oxide.

[0069] The material of the first hole transport layer 21 includes: a self-assembly material and a first functional material. The first functional material includes an oxygen-containing acid group.

[0070] The main function of the hole transport layer 20 material is to transport holes to facilitate the transport of charges within the solar cell 100. In the solar cell 100, the hole transport material can receive holes excited from the absorption layer 30 and transport them to the anode of the solar cell 100, thereby completing the separation and collection of charges.

[0071] The perovskite material of the absorption layer 30 has high photoelectric conversion efficiency and good stability. In the solar cell 100, the absorption layer 30 is responsible for absorbing sunlight and generating photogenerated carriers (electrons and holes).

[0072] The self-assembled material of the first hole transport layer 21 can arrange itself into an ordered structure, thereby optimizing the charge transport path and improving the charge transport efficiency.

[0073] The nickel oxide of the second hole transport layer 22 is located between the first hole transport layer 21 and the electrode 60, which can further promote the transmission of photogenerated holes from the absorption layer 30 to the electrode 60. Nickel oxide is a semiconductor material with a wide band gap and good conductivity. Its special energy level structure and material design enable nickel oxide to efficiently transport holes, thereby improving the photoelectric conversion efficiency. In addition, the nickel oxide material has good chemical stability and thermal stability, which can improve the stability of the solar cell 100. One of the most effective hole transport materials for the stable operation of the solar cell 100. Moreover, the nickel oxide-based inverted solar cell 100 is also highly compatible with the development of flexible or stacked solar cells 100.

[0074] However, the hydroxyl groups in the nickel oxide will harm the absorption layer 30. The hydroxyl groups are derived from the chemical reactions in the preparation process or post-processing steps of the nickel oxide, that is, the hydroxyl groups will react with the ions in the absorption layer 30 to form unstable compounds, thereby affecting the stability and photoelectric performance of the absorption layer 30. In addition, due to the contact interface defects at the interface between the substrate and the nickel oxide, and the nickel oxide and the perovskite layer, the heterogeneous interface contact formed will cause carrier accumulation and accumulation of invalid charge transport at the interface of the solar cell, leading to non-radiative recombination, contact interface collapse and other problems.

[0075] Therefore, the oxygen-containing acid groups in the first functional material in the first hole transport layer 21 can react with the hydroxyl groups to form chemical bonds, thereby reducing the hydroxyl content in the nickel oxide, passivating the contact interface defects between the absorption layer 30 and the hole transport layer 20, reducing the non-radiative recombination caused by the defects, and enhancing the interface bonding force and charge transfer efficiency between the first hole transport layer 21 and the second hole transport layer 22, thereby improving the charge injection effect between the absorption layer 30 and the hole transport layer 20 and improving the charge transfer efficiency. At the same time, the stability and durability of the second hole transport layer 22 can also be enhanced, thereby improving the overall performance of the solar cell 100.

[0076] In addition, the self-assembled material and the first functional material work together, the self-assembled material optimizes the charge transfer path and improves the charge transfer efficiency, the first functional material reduces the hydroxyl group in the nickel oxide on the second hole transport layer 22, passivates the contact interface defects between the absorption layer 30 and the hole transport layer 20, improves the charge injection effect between the absorption layer 30 and the hole transport layer 20, reduces the non-radiative recombination caused by the defects, improves the carrier extraction efficiency, and jointly improves the efficiency and stability of the solar cell 100.

[0077] In some embodiments, the oxoacid group comprises at least one of a carboxyl group, a boronic acid group, or a phosphonic acid group.

[0078] It can be understood that at least one of the carboxyl group, the boric acid group or the phosphonic acid group can form a stable chemical bond with the hydroxyl group on the surface of the nickel oxide, thereby adhering to the surface of the nickel oxide; as a hole transport material, the nickel oxide has some defects on the surface, such as oxygen vacancies, metal ion vacancies, etc., which will affect the electrical properties and stability of the nickel oxide. By introducing the first functional material that can react with the hydroxyl group in the nickel oxide, these defects can be passivated, reducing the adverse effects on the performance of the solar cell 100 and improving the performance of the solar cell 100. In addition, the first functional material can be located between the nickel oxide and the absorption layer 30, slowing down the heterogeneous interface contact between the nickel oxide and the perovskite layer, reducing non-radiative recombination, and further improving the performance of the solar cell 100; it can also improve the interface compatibility between the first functional material and the nickel oxide, promote the effective transmission of holes, and thus improve the performance of the solar cell 100.

[0079] In some embodiments, the first functional material further includes: an amino group.

[0080] It can be understood that the amino group can be connected to the group (such as the phosphonic acid group) in the self-assembled material through an ionic bond, so that the self-assembled material is more closely connected to the nickel oxide, further improving the heterogeneous interface contact between the absorption layer 30 and the hole transport layer 20, reducing non-radiative recombination, and further improving the performance of the solar cell 100.

[0081] In some embodiments, the first functional material further comprises: a connecting group. The connecting group comprises: at least one of a phenyl group and a C1-C6 alkylene group.

[0082] It can be understood that the linking group is located between the oxygen-containing acid group and the amino group, playing the role of a spacer and a bridge, ensuring that the first functional material has good stability and durability.

[0083] Phenyl is an aromatic atomic group. The aromaticity makes the arylene group relatively stable chemically, which helps to enhance the charge transport performance and stability of the material.

[0084] The alkylene group of C1 to C6 is a chain structure composed of carbon and hydrogen atoms, which has good flexibility, so that the alkylene group can adapt to different spatial configuration requirements when connecting the first functional material and the third group, and has small steric hindrance; and the alkylene group is relatively stable chemically and not easy to react, which helps to ensure the stability of the hole transport material during preparation and use.

[0085] In some embodiments, the first functional material includes at least one of p-aminobenzoic acid, glycine, and 4-aminobutyric acid.

[0086] It can be understood that p-aminobenzoic acid, glycine and 4-aminobutyric acid all contain amino groups and carboxyl groups; taking p-aminobenzoic acid as an example, Figure 5 As shown, the amino group in p-aminobenzoic acid can be connected to the group (such as the phosphonic acid group) in the self-assembly material through an ionic bond, so that the self-assembly material is tightly connected to the nickel oxide, thereby improving the performance of the solar cell 100; the carboxyl group can react with the hydroxyl group on the surface of the nickel oxide to form a chemical bond, thereby reducing the interface defects of the nickel oxide layer, improving the interface compatibility between the self-assembly material and the nickel oxide, and promoting the effective transmission of holes, thereby improving the performance of the solar cell 100.

[0087] In some embodiments, the mass ratio of the self-assembly material to the first functional material is in the range of 0.5:(0.05-3).

[0088] Illustratively, the mass ratio of the self-assembly material to the first functional material can be 0.5:0.05, 0.5:1.5, 0.5:2, 0.5:2.5 or 0.5:3, etc., which is not limited here.

[0089] Through the above configuration, the self-assembled material can be further closely connected with the nickel oxide, thereby improving the interface performance between the first hole transport layer 21 and the nickel oxide layer, promoting the effective transport of holes, and thus improving the performance of the solar cell 100 .

[0090] In some embodiments, the material of the first hole transport layer further includes: a second functional material. The second functional material includes: at least one of alkali metal halide, alkaline earth metal halide and ammonium halide.

[0091] Halogen is a highly electronegative element that can form stable ionic bonds with cations. In the second functional material, halogen exists in the form of anions. Halogen anions can form ionic dipole effects with polar parts of the self-assembled material molecules (such as the electron cloud around nitrogen atoms), which helps to stabilize the hole transport layer 20, promote the effective transfer of charges between layers, and improve the carrier extraction efficiency.

[0092] Illustratively, the halogen may be fluorine, chlorine, bromine, iodine, and the like.

[0093] The halogen ions in the second functional material can form an ion dipole effect with the self-assembly material (e.g., the carbazole group in the self-assembly material molecule), which can enhance the connection between the absorption layer 30 and the hole transport layer 20, passivate the surface defects of the perovskite, improve the stability of the interface, and improve the interface contact performance between the absorption layer 30 and the hole transport layer 20. At the same time, it can also promote the uniform growth of the perovskite crystals, further improving the efficiency and stability of the solar cell 100.

[0094] The alkali metal elements, alkaline earth metal elements and ammonium ions in the second functional material can stabilize the lattice structure of the perovskite, reduce defects at the grain boundaries, passivate defects on the surface of the perovskite, thereby reducing non-radiative recombination caused by defects and improving the extraction efficiency of carriers. In addition, the perovskite material includes iodine. The alkali metal elements can be connected to the iodine in the perovskite material. Figure 5 As shown, alkali metal elements and alkaline earth metal elements (such as potassium) can pair with iodine defects in the perovskite material to form connections, thereby passivating iodine interstitial defects and inhibiting non-radiative electron-hole recombination, thereby improving the photoelectric conversion efficiency and stability of the solar cell 100.

[0095] Illustratively, the alkali metal element may be lithium, sodium, potassium, and the like.

[0096] Illustratively, the alkaline earth metal element may be magnesium, calcium, strontium, barium, and the like.

[0097] Therefore, the self-assembled material and the second functional material work together, the self-assembled material transports holes, and the second functional material optimizes the performance of the solar cell 100 by passivating perovskite surface defects, enhancing interface connections and promoting uniform growth of perovskite crystals, thereby jointly improving the efficiency and stability of the solar cell 100.

[0098] In some embodiments, the second functional material further includes fluorine element.

[0099] The fluorine element can combine with the defect sites in the absorption layer 30 to reduce the number of defects, thereby reducing the charge recombination phenomenon and improving the photoelectric conversion efficiency; the fluorine element can change the electron cloud distribution around the passivation group, optimize the interface contact between the absorption layer 30 and the hole transport layer 20, and improve the charge transfer efficiency; moreover, through the interaction between the fluorine element and iodine, the stability of the perovskite film can be significantly enhanced, thereby extending the service life of the solar cell 100.

[0100] like Figure 5 As shown, the fluoride ions in potassium fluoride can form an ion dipole effect with the polar part (such as carbazole group) in the self-assembled material, which helps to stabilize the hole transport layer 20, promote the effective transfer of charge between layers, and improve the carrier extraction efficiency. It not only improves the hole transport performance, but also reduces non-radiative recombination through synergistic passivation, thereby further improving the performance of the solar cell 100.

[0101] In some embodiments, the second functional material includes at least one of potassium fluoride, sodium fluoride, and ammonium fluoride.

[0102] It can be understood that at least one of the second functional materials of potassium fluoride, sodium fluoride and ammonium fluoride can passivate the defects on the surface of the perovskite, thereby reducing charge recombination and improving the extraction efficiency of carriers.

[0103] In some embodiments, the mass ratio of the self-assembly material to the second functional material is in the range of 0.5:(0.05-3).

[0104] Illustratively, the mass ratio of the self-assembly material to the second functional material can be 0.5:0.05, 0.5:1.5, 0.5:2, 0.5:2.5 or 0.5:3, etc., which is not limited here.

[0105] Through the above configuration, the interface compatibility between the hole transport material and the nickel oxide can be further improved, the effective transport of holes can be promoted, and the performance of the solar cell 100 can be improved.

[0106] In some embodiments, the self-assembled material includes at least one of (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, and [2-(9H-carbazol-9-yl)ethyl]phosphonic acid.

[0107] It can be understood that (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [2-(9H-carbazole-9-yl)ethyl]phosphonic acid all contain carbazole groups and phosphonic acid groups. Taking (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid as an example, Figure 5 As shown in the figure, the carbazole group in the molecular structure of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid forms a stable conjugated system with a benzene ring and a pyridine ring, which makes the carbazole group have a high hole mobility and good electron donation, and can effectively receive and transmit holes excited from the photoactive layer; the carbazole group is an aromatic compound with excellent photoelectric properties, and the phosphonic acid group can react with the hydroxyl group on the surface of nickel oxide. Therefore, any one of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [2-(9H-carbazole-9-yl)ethyl]phosphonic acid can improve the performance of the nickel oxide surface, reduce surface defects, and improve the hole transmission efficiency. Furthermore, the carbazole group can form an ion dipole effect with a halogen (such as fluorine), which helps to stabilize the hole transport layer 20 and promote the effective transfer of charges between layers, thereby improving the performance of the solar cell 100 .

[0108] In some embodiments, the thickness of the first hole transport layer 21 is in the range of 5 nm to 10 nm.

[0109] For example, the thickness of the first hole transport layer 21 may be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, etc., which is not limited here.

[0110] It can be understood that, through the above arrangement, the hole transport efficiency can be enhanced, and the effective transport of charges between the absorption layer 30 and the hole transport layer can be promoted.

[0111] In some embodiments, the absorption layer 30 has a thickness ranging from 550 nm to 600 nm.

[0112] Illustratively, the thickness of the absorption layer 30 may be 550 nm, 560 nm, 570 nm, 580 nm, 590 nm or 600 nm, etc., which is not limited herein.

[0113] It can be understood that, through the above configuration, the absorption layer 30 can fully absorb sunlight while maintaining a relatively high photoelectric conversion efficiency.

[0114] In some embodiments, the absorption layer 30 further includes 4-fluoro-phenylethyl ammonium iodide on one side close to the hole transport layer 20. 4-fluoro-phenylethyl ammonium iodide can promote the growth of perovskite crystals along a specific direction (e.g., (100) orientation), thereby improving the crystallinity and orientation of the crystals; 4-fluoro-phenylethyl ammonium iodide can also spontaneously form a layered perovskite structure at the grain boundary and surface of the perovskite crystal, effectively passivating defects and improving the performance of the solar cell 100.

[0115] In some embodiments, the second hole transport layer 22 has a thickness ranging from 10 nm to 20 nm.

[0116] For example, the thickness of the second hole transport layer 22 may be 10 nm, 12 nm, 14 nm, 16 nm, 18 nm or 20 nm, etc., which is not limited here.

[0117] It can be understood that the second hole transport layer 22 can effectively promote the transport of photogenerated holes from the absorption layer 30 to the electrode 60, while blocking the reverse flow of electrons, thereby reducing charge recombination and improving the photoelectric conversion efficiency of the battery.

[0118] The embodiment of the present application provides a method for preparing a solar cell 100. Figure 6 As shown, the method for preparing the solar cell 100 includes: S1 to S3.

[0119] S1: forming a second hole transport layer 22; the material of the second hole transport layer 22 includes nickel oxide.

[0120] S2: forming a first hole transport layer 21 on one side of the second hole transport layer 22; the second hole transport layer 22 is in contact with the first hole transport layer 21; the material of the first hole transport layer 21 includes: a self-assembly material and a first functional material; the first functional material includes an oxygen-containing acid group.

[0121] S3: forming an absorption layer 30 on a side of the first hole transport layer 21 away from the second hole transport layer 22; the material of the absorption layer 30 includes a perovskite material.

[0122] In some embodiments, S2 forms a first hole transport layer 21 on one side of the second hole transport layer 22 , including: S2.1 ˜ S2.2 .

[0123] S2.1: coating a first solution on one side of the second hole transport layer 22 , wherein the first solution includes a first functional material.

[0124] S2.2: performing annealing treatment on the first solution.

[0125] In some embodiments, the concentration of the first functional material in the first solution is in the range of 0.05 mg / mL to 3 mg / mL.

[0126] Illustratively, the concentration of the first functional material in the first solution can be 0.05 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL or 3 mg / mL, etc., which is not limited here.

[0127] It should be noted that the mass of the first functional material used in the preparation process is the mass of the first functional material in the prepared solar cell 100. For example, 3 mg of p-aminobenzoic acid (PABA) is added to 1 ml of anhydrous ethanol to dissolve to form 3 mg / mL of p-aminobenzoic acid, which is then coated to form a hole transport layer 20 to prepare the solar cell 100. The mass of p-aminobenzoic acid in the solar cell 100 is 3 mg.

[0128] In some embodiments, the first solution further comprises a second functional material. The concentration of the second functional material in the first solution ranges from 0.05 mg / mL to 3 mg / mL. The second functional material comprises: at least one of an alkali metal halide, an alkaline earth metal halide and an ammonium halide.

[0129] Illustratively, the concentration of the second functional material in the first solution can be 0.05 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL or 3 mg / mL, etc., which is not limited here.

[0130] It should be noted that the mass of the second functional material used in the preparation process is the mass of the second functional material in the prepared solar cell 100 .

[0131] In some embodiments, the temperature of the annealing process is in a range of 90°C to 110°C.

[0132] Illustratively, the temperature of the annealing treatment may be 90° C., 95° C., 100° C., 105° C., or 110° C., etc., which is not limited herein.

[0133] In some embodiments, the annealing treatment time ranges from 8 min to 12 min.

[0134] For example, the annealing time may be 8 min, 9 min, 10 min, 11 min or 12 min, etc., which is not limited here.

[0135] The present application is further described in detail below by taking several specific experiments as examples and combining with the accompanying drawings.

[0136] Example 1

[0137] Embodiment 1 provides a solar cell 100. The preparation method of the solar cell 100 is as follows:

[0138] R1: The FTO conductive glass was scrubbed with tsa-tsa-klin, and then ultrasonicated with a detergent, deionized water, and anhydrous ethanol for 20 min respectively, dried with nitrogen, and treated with a plasma cleaner for 10 min to obtain substrate 10;

[0139] R2: The nickel oxide nanocrystalline powder is dispersed in pure water by ultrasonication to form a 10 mg / ml nickel oxide precursor liquid; the nickel oxide precursor liquid is spin-coated onto FTO at 4000 rpm for 40 seconds, and then annealed at 150° C. for 10 minutes to form a second hole transport layer 22 with a thickness of 10 nm;

[0140] R3: Add 1 ml of anhydrous ethanol to 0.05 mg of p-aminobenzoic acid and 0.5 mg of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid to dissolve, and mix 0.05 mg / ml of p-aminobenzoic acid and 0.5 mg / ml of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid to form a first hole transport layer 21 material solution; then spin-coat the first hole transport layer 21 material solution at 5000 rpm for 30 seconds, and anneal at 100° C. for 10 minutes after the spin coating to form a first hole transport layer 21 with a thickness of 8 nm;

[0141] R4: MABr, CsI, PbI2, FAI, PbBr2 are configured to form a perovskite solution of Cs0.05(FA0.92MA0.08)0.95Pb(I0.92Br0.08)3 with a concentration of 1.4M, and 4-fluoro-phenylethylammonium iodide is dissolved in ethyl acetate to form a 4-fluoro-phenylethylammonium iodide solution with a concentration of 0.2mg / ml. Then the perovskite solution is spin-coated on the second hole transport layer 22 at 4000rpm for 40s, and 200μL of 4-fluoro-phenylethylammonium iodide solution is added 10s before the end of spin coating. After the spin coating is completed, annealing is performed at 120°C for 20min to form an absorption layer 30 with a thickness of 580nm;

[0142] R5: Using C60 powder to form an electron transport layer 40 with a thickness of 30 nm on the absorption layer 30 by high temperature evaporation;

[0143] R6: dissolving 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in an isopropanol solution to form a BCP solution with a concentration of 0.5 mg / ml; spin coating the BCP solution on the electron transport layer 40 at 4000 rpm for 30 seconds to form a hole blocking layer 50;

[0144] R7: A silver metal electrode 60 with a thickness of 100 nm is evaporated on the hole blocking layer 50 .

[0145] Example 2

[0146] Example 2 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 1, except that in R3, the amount of p-aminobenzoic acid used is 1 mg, and the obtained p-aminobenzoic acid concentration is 1 mg / ml.

[0147] Example 3

[0148] Example 3 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 1, except that in R3, the amount of p-aminobenzoic acid used is 6 mg, and the obtained p-aminobenzoic acid concentration is 6 mg / ml.

[0149] Example 4

[0150] Embodiment 4 provides a solar cell 100, and the preparation method of the solar cell 100 is the same as that of Embodiment 1, except that 1 mg of potassium fluoride is further added to R3; specifically, 1 ml of anhydrous ethanol is added to 0.05 mg of p-aminobenzoic acid, 1 mg of potassium fluoride and 0.5 mg of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid to dissolve, and 0.05 mg / ml of p-aminobenzoic acid, 1 mg / ml of potassium fluoride and 0.5 mg / ml of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid are mixed evenly to form a first hole transport layer 21 material solution.

[0151] Example 5

[0152] Example 5 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 4, except that in R3, the amount of p-aminobenzoic acid used is 1 mg, and the obtained p-aminobenzoic acid concentration is 1 mg / ml.

[0153] Example 6

[0154] Example 6 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 4, except that in R3, the amount of p-aminobenzoic acid used is 3 mg, and the obtained p-aminobenzoic acid concentration is 3 mg / ml.

[0155] Example 7

[0156] Example 7 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 4, except that in R3, the amount of p-aminobenzoic acid used is 6 mg, and the obtained p-aminobenzoic acid concentration is 6 mg / ml.

[0157] Example 8

[0158] Example 8 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 5, except that in R3, the amount of potassium fluoride used is 0.05 mg, and the obtained concentration of potassium fluoride is 0.05 mg / ml.

[0159] Example 9

[0160] Example 9 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 5, except that in R3, the amount of potassium fluoride used is 6 mg, and the obtained potassium fluoride concentration is 6 mg / ml.

[0161] Example 10

[0162] Embodiment 10 provides a solar cell 100, and the preparation method of the solar cell 100 is the same as that of Embodiment 1, except that, in R3, p-aminobenzoic acid is not added to the first hole transport layer 21 material solution; specifically, 1 ml of anhydrous ethanol is added to 0.05 mg of potassium fluoride and 0.5 mg of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid to dissolve, and 0.05 mg / ml of potassium fluoride and 0.5 mg / ml of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid are mixed evenly to form the first hole transport layer 21 material solution.

[0163] Embodiment 11

[0164] Example 11 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 10, except that in R3, the amount of potassium fluoride used is 1 mg, and the obtained concentration of potassium fluoride is 1 mg / ml.

[0165] Example 12

[0166] Example 12 provides a solar cell 100. The preparation method of the solar cell 100 is the same as that of Example 10, except that in R3, the amount of potassium fluoride used is 6 mg, and the obtained potassium fluoride concentration is 6 mg / ml.

[0167] Comparative Example 1

[0168] Comparative Example 1 provides a solar cell 100, and the preparation method of the solar cell 100 is the same as that of Example 1, except that potassium fluoride and para-aminobenzoic acid are not added to the first hole transport layer 21 material solution in S3; specifically: 1 ml of anhydrous ethanol is added to 0.5 mg of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid to dissolve and form a first hole transport layer 21 material solution.

[0169] Performance Testing

[0170] 1. Current density-voltage (JV) test: The solar cell 100 of the above embodiment and comparative example was tested for JV using a Keithley 2400 source under simulated amplitude modulation, and a solar simulator based on a xenon lamp was used for 1.5G illumination (100 mW / cm2), and the effective area of ​​the device was 0.16 cm2. The results are shown in Table 1. Figure 2 and Figure 3 shown.

[0171] Table 1 Performance test results of embodiments and comparative examples

[0172]

[0173]

[0174] As can be seen from Table 1, the open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency of the solar cell 100 of Examples 1 to 9 are all higher than those of Comparative Example 1, indicating that the solar cell 100 of Examples 1 to 9 can maintain a higher voltage in the open circuit state, can generate more current under the short circuit condition, has a higher efficiency at the maximum output power point and performs better in converting light energy into electrical energy, thereby improving the performance of the solar cell 100.

[0175] like Figure 2 As shown, Figure 2 1 is the forward and reverse sweep curves of the current density-voltage test of the solar cell 100 of Example 5. It can be seen that the difference between the forward and reverse sweep curves is small, indicating that the performance of the solar cell 100 of Example 5 is relatively stable.

[0176] like Figure 3 As shown, Figure 3 3 is a current density-voltage curve test diagram of the solar cell 100 of Example 5 and Comparative Example 1. It can be seen that the open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency of the solar cell 100 of Example 5 are higher than those of Comparative Example 1, indicating that the performance of the solar cell 100 of Example 5 is better than that of the solar cell 100 of Comparative Example 1.

[0177] 2. External quantum efficiency test

[0178] The solar cell 100 of the above-mentioned Example 5 and Comparative Example 1 was tested using the Zhuoli Hanguang Solar Cell 100 Quantum Efficiency Test System SCS-600MAX. The results are as follows: Figure 4 shown.

[0179] like Figure 4 As shown, Figure 4 is a test graph of the external quantum efficiency of the solar cell 100 of Example 5 and Comparative Example 1. Figure 4 It can be seen that the main light response range of the solar cell 100 of comparative example 1 is 300nm~800nm ​​band, and the integrated current density is 24.13mA / cm2, which is consistent with the short-circuit current density result of the current density-voltage test. The main light response range of the solar cell 100 of Example 5 is 300nm~800nm ​​band, and the integrated current density is 25.59mA / cm2, which is consistent with the short-circuit current density result of the current density-voltage test. It shows that the solar cell 100 of Example 5 has a higher light energy conversion efficiency in the same wavelength range, thereby generating a larger short-circuit current density.

[0180] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A solar cell, characterized in that: include: Absorption layer; the material of the absorption layer includes perovskite material; a first hole transport layer; as well as, a second hole transport layer, located on a side of the first hole transport layer away from the absorption layer and in contact with the first hole transport layer; The material of the second hole transport layer includes nickel oxide; The material of the first hole transport layer includes: a self-assembly material and a first functional material; the first functional material includes an oxygen-containing acid group.

2. The solar cell according to claim 1, characterized in that The oxygen-containing acid group includes at least one of a carboxyl group, a boric acid group or a phosphonic acid group.

3. The solar cell according to claim 1, characterized in that The first functional material further includes: amino group.

4. The solar cell according to claim 1, characterized in that The first functional material includes a connecting group, and the connecting group includes at least one of a phenyl group and a C1-C6 alkylene group.

5. The solar cell according to claim 4, characterized in that: The first functional material includes at least one of p-aminobenzoic acid, glycine and 4-aminobutyric acid.

6. The solar cell according to claim 1, characterized in that The mass ratio of the self-assembly material to the first functional material is in the range of 0.5:(0.05-3).

7. The solar cell according to any one of claims 1 to 6, characterized in that: The material of the first hole transport layer also includes: a second functional material; The second functional material includes at least one of an alkali metal halide, an alkaline earth metal halide and an ammonium halide.

8. The solar cell according to claim 7, characterized in that: The second functional material also includes: fluorine element.

9. The solar cell according to claim 8, characterized in that The second functional material includes at least one of potassium fluoride, sodium fluoride and ammonium fluoride.

10. The solar cell according to claim 7, characterized in that: The mass ratio of the self-assembly material to the second functional material is in the range of 0.5:(0.05-3).

11. The solar cell according to any one of claims 1 to 10, characterized in that: The self-assembly material includes at least one of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [2-(9H-carbazole-9-yl)ethyl]phosphonic acid.

12. The solar cell according to claim 1, characterized in that The thickness of the first hole transport layer is in the range of 5 nm to 10 nm.

13. The solar cell according to claim 1, characterized in that The thickness of the absorption layer ranges from 550nm to 600nm.

14. The solar cell according to claim 1, characterized in that The thickness of the second hole transport layer is in the range of 10 nm to 20 nm.

15. A method for preparing a solar cell, wherein the solar cell is the solar cell according to any one of claims 1 to 14, characterized in that: include: forming a second hole transport layer; the material of the second hole transport layer includes nickel oxide; forming a first hole transport layer on one side of the second hole transport layer; The second hole transport layer is in contact with the first hole transport layer; The material of the first hole transport layer includes: a self-assembly material and a first functional material; the first functional material includes an oxygen-containing acid group; The absorption layer is formed on a side of the first hole transport layer away from the second hole transport layer; the material of the absorption layer includes a perovskite material.

16. The method for preparing a solar cell according to claim 15, characterized in that: The forming of the first hole transport layer on one side of the second hole transport layer comprises: A first solution is coated on one side of the second hole transport layer and subjected to annealing treatment, wherein the first solution includes the first functional material.

17. The method for preparing a solar cell according to claim 16, characterized in that: The concentration of the first functional material in the first solution is in the range of 0.05 mg / mL to 3 mg / mL.

18. The method for preparing a solar cell according to claim 16, characterized in that: The first solution further includes a second functional material; the concentration of the second functional material in the first solution is in the range of 0.05 mg / mL to 3 mg / mL; and / or, The second functional material includes at least one of an alkali metal halide, an alkaline earth metal halide and an ammonium halide.

19. The method for preparing a solar cell according to claim 16, characterized in that: The temperature range of the annealing treatment is 90° C. to 110° C.; and / or the time range of the annealing treatment is 8 min to 12 min.

20. A photovoltaic cell assembly, characterized in that: include: A solar cell as claimed in any one of claims 1 to 14.

21. A photovoltaic cell system, characterized in that: include: An inverter and the photovoltaic cell assembly as claimed in claim 20, wherein the inverter is electrically connected to the photovoltaic cell assembly.

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