Solar cell and preparation method thereof

Abstract

The invention relates to a solar cell and a preparation method thereof. The solar cell comprises a light absorption layer, a hole modification layer and a hole transmission layer which are arranged in a stacked mode. The hole modification layer is located between the light absorption layer and the hole transmission layer; the material of the hole modification layer comprises at least one of self-assembled monomolecular layer materials and at least one of polyoxometallate. According to the solar cell, the hole extraction capability of the hole transport layer can be improved, the hole mobility of an interface is improved, and the high photoelectric conversion efficiency of the solar cell is further achieved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a solar cell and its preparation method. Background Technology

[0002] Single-junction perovskite solar cells typically consist of a transparent conductive layer, an electron transport layer, a perovskite layer, a hole transport layer, and electrodes (nip structure) or a transparent conductive layer, hole transport layer, perovskite layer, electron transport layer, and electrodes (pin structure). The perovskite layer is a light-absorbing layer; when the perovskite solar cell is exposed to sunlight, it absorbs light and generates excitons. At the interface between the perovskite layer and the charge transport layer, the excitons dissociate, generating charge carriers (electrons and holes). Electrons enter the electron transport layer, and holes enter the hole transport layer. The electrons and holes reach the working electrode and counter electrode, respectively, and generate current through the external circuit.

[0003] However, the hole transport layer in traditional solar cells has a limited ability to extract holes generated by the light-absorbing layer, resulting in a low hole mobility at the interface between the light-absorbing layer and the hole transport layer, which in turn limits the improvement of the conversion efficiency of solar cells. Summary of the Invention

[0004] Therefore, it is necessary to provide a solar cell and its fabrication method. The solar cell of this application can improve the hole extraction capability of the hole transport layer and increase the hole mobility at the interface between the light-absorbing layer and the hole transport layer, thereby achieving a higher photoelectric conversion efficiency of the solar cell.

[0005] In a first aspect, this application provides a solar cell, including a light-absorbing layer, a hole-modifying layer, and a hole-transporting layer stacked together; the hole-modifying layer is located between the light-absorbing layer and the hole-transporting layer; the material of the hole-modifying layer includes at least one of self-assembled monolayer materials and at least one of polyoxometalates.

[0006] In some embodiments, the mass ratio of the self-assembled monolayer material to the polyoxometalate in the hole-modified layer is 1:(0.1~0.3).

[0007] In some embodiments, the self-assembled monolayer material includes at least one of 2PACz, MeO-PACz, and Me-4PACz.

[0008] In some embodiments, the polyoxometalate includes XM 12 O 40 X2M 18 O 62 XM6O 24 XM9O 32and XM 12 O 42 At least one of the following, wherein X is selected from at least one of P, Si, and As, and M is selected from Mo. 6+ W 6+ and V 5+ At least one of them.

[0009] In some embodiments, the polyoxometalate includes at least one of phosphomolybdic acid and phosphotungstic acid.

[0010] In some embodiments, the surface roughness Rz of the hole-modified layer is less than 2 nm.

[0011] In some embodiments, the solar cell includes at least one of a perovskite solar cell, a perovskite / silicon tandem cell, and a perovskite / perovskite tandem cell.

[0012] In some embodiments, the light-absorbing layer is a perovskite layer, which comprises a material having the following general chemical formula: ABY3, wherein A is selected from FA. + MA + Cs + and Rb + At least one of them, B is selected from Pb 2+ Sn 2+ and Sr 2+ At least one of them, Y is selected from Cl - ,Br - and I - At least one of them.

[0013] In some embodiments, the material of the hole transport layer includes at least one of metal oxide hole transport materials.

[0014] Secondly, this application provides a method for fabricating a solar cell, comprising the following steps:

[0015] A hole-modifying layer is prepared on the surface of a hole transport layer, wherein the material of the hole-modifying layer includes at least one of self-assembled monolayer materials and at least one of polyoxometalates;

[0016] A light-absorbing layer is prepared on the surface of the hole-modified layer.

[0017] In some embodiments, the method for preparing the hole-modified layer includes the following steps:

[0018] The self-assembled monolayer material and the polyoxometalate are mixed in a solvent to obtain a mixed solution;

[0019] The mixed solution is coated onto the surface of the hole transport layer and then annealed to obtain the hole-modified layer.

[0020] In the aforementioned solar cell, the hole modification layer located between the hole transport layer and the light-absorbing layer comprises at least one of self-assembled monolayer materials and at least one of polyoxometalates. Compared to solar cells without a hole modification layer where the hole transport layer is in direct contact with the light-absorbing layer, the hole modification layer of this application can effectively passivate vacancy defects on the surface of the hole transport layer, improve the film quality of the light-absorbing layer, and thus improve the conversion efficiency of the solar cell. Compared to solar cells that only use self-assembled monolayer materials as the hole modification layer, in the hole modification layer of the solar cell of this application, the polyoxometalates can effectively alleviate the spontaneous aggregation of the self-assembled monolayer materials, thereby reducing the uneven coverage of the hole modification layer on the hole transport layer caused by the aggregation of the self-assembled monolayer materials. This reduces the problems of energy level mismatch, hole transport obstruction, and recombination aggravation caused by uneven coverage, thereby improving the hole extraction capability of the hole transport layer, increasing the hole mobility at the interface, and thus improving the conversion efficiency of the solar cell. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a solar cell provided in one embodiment of this application.

[0022] Explanation of reference numerals in the attached figures

[0023] 1-Bottom electrode; 2-First transparent conductive layer; 3-First doped silicon layer; 4-First intrinsic silicon layer; 5-Silicon substrate; 6-Second intrinsic silicon layer; 7-Second doped silicon layer; 8-Carrier recombination layer; 9-Hole transport layer; 10-Hole modification layer; 11-Perovskite layer; 12-Passivation layer; 13-Electron modification layer; 14-Electron transport layer; 15-Second transparent conductive layer; 16-Top electrode. Detailed Implementation

[0024] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] The inventors discovered that in traditional solar cells, the poor bandgap matching between the hole transport layer and the perovskite layer leads to poor hole extraction capability of the hole transport layer. Self-assembled monolayers (SAMs) materials have tunable work functions, enabling bandgap continuity with both the perovskite and hole transport materials, thus optimizing the hole extraction capability of the hole transport layer. However, SAMs materials possess polar heads and nonpolar tails. This structure causes SAMs to spontaneously aggregate into island-like structures in solvents, resulting in poor uniformity of SAM coverage on the hole transport layer when preparing hole-modifying layers. This, in turn, easily leads to energy level mismatch, hindered hole transport, and increased recombination among the perovskite layer, hole-modifying layer, and hole transport layer.

[0030] To solve the above problems, refer to Figure 1 As shown, one embodiment of this application provides a solar cell, including a light-absorbing layer, a hole-modifying layer 10, and a hole-transporting layer 9 stacked together; the hole-modifying layer 10 is located between the light-absorbing layer and the hole-transporting layer 9; the material of the hole-modifying layer 10 includes at least one of self-assembled monolayer materials and at least one of polyoxometalates.

[0031] In the aforementioned solar cell, the hole modification layer 10, located between the hole transport layer 9 and the light-absorbing layer, is made of at least one of self-assembled monolayer materials and at least one of polyoxometalates. Compared to solar cells without a hole modification layer 10 where the hole transport layer 9 is in direct contact with the light-absorbing layer, the hole modification layer 10 of this application can effectively passivate vacancy defects on the surface of the hole transport layer 9, improve the film quality of the light-absorbing layer, and thus improve the conversion efficiency of the solar cell. Compared to solar cells that use only self-assembled monolayer materials as hole modification layers 10, the polyoxometalates in the hole modification layer 10 of the solar cell of this application can effectively alleviate the spontaneous aggregation of self-assembled monolayer materials, thereby reducing the uneven coverage of the hole modification layer 10 on the hole transport layer 9 caused by the aggregation of self-assembled monolayer materials. This reduces the problems of energy level mismatch, hole transport obstruction, and recombination aggravation caused by uneven coverage, thereby improving the hole extraction capability of the hole transport layer 9, increasing the hole mobility at the interface, and thus improving the conversion efficiency of the solar cell.

[0032] Specifically, polyoxometalates (POMs) have oxygen atoms (terminal oxygen O-) enriched on their surface, exhibiting a high negative charge density, which allows them to interact with positively charged hole transport layers (such as NiO). xStrong bonds are formed on the surface of SAMs, and polar groups (such as phosphonic acid groups) in SAMs materials are fixed through hydrogen bonds and dipole interactions, inhibiting the aggregation of SAMs materials. Simultaneously, the rigid, large-size structure of POMs materials can physically separate SAMs molecules, reducing the intermolecular packing density. Furthermore, taking perovskite solar cells as an example, POMs materials also possess a suitable band structure, with their conduction band located between the perovskite material and the hole transport material (such as NiO). x The presence of these elements facilitates hole extraction. Furthermore, taking perovskite tandem solar cells as an example, POMs materials possess both Lewis acidity (metal sites) and Brønsted acidity (surface protonated oxygen), enabling them to passivate uncoordinated Pb through Lewis acid sites. 2+ and I - Furthermore, it can adsorb free MA⁺ / FA⁺ ions at the interface through Brønsted acid sites, inhibiting ion migration and penetration, and blocking electrochemical corrosion pathways. Additionally, some POMs materials (such as [H₂W₂]) can... 12 O 40 ] 6- It exhibits characteristic absorption in the near-infrared region (700nm~1000nm), and can transfer high-energy photon energy to silicon-based solar cells through a downconversion mechanism, compensating for the insufficient red light response of perovskite and further improving the conversion efficiency of solar cells.

[0033] Understandable Figure 1 The example shown is merely a perovskite / silicon-based tandem solar cell, illustrating the structure of one type of solar cell in this application. It should not be construed as a limitation on the specific structure of the solar cell in this application.

[0034] In some embodiments, the mass ratio of the self-assembled monolayer material to the polyoxometalate in the hole-modified layer 10 is 1:(0.1~0.3).

[0035] Within the aforementioned mass ratio range of the self-assembled monolayer material and the polyoxometalate, it is convenient to achieve a better improvement effect of the polyoxometalate on the aggregation of the self-assembled monolayer material, as well as better band continuity between the hole modification layer 10 and the light-absorbing layer and the hole transport layer 9. Optionally, in the hole modification layer 10, the mass ratio of the self-assembled monolayer material to the polyoxometalate is 1:0.1, 1:0.15, 1:0.2, 1:0.25, or 1:0.3, or the mass ratio of the self-assembled monolayer material to the polyoxometalate in the hole modification layer 10 can also be within the range between any two of the above mass ratios.

[0036] In some embodiments, the self-assembled monolayer material includes at least one of 2PACz, MeO-PACz, and Me-4PACz.

[0037] In some embodiments, polyoxometalates include XM 12 O 40 X2M 18 O 62 XM6O 24 XM9O 32 and XM 12 O 42 At least one of the following, wherein X is selected from at least one of P, Si, and As, and M is selected from Mo. 6+ W 6+ and V 5+ At least one of them.

[0038] In some embodiments, polyoxometalates include phosphomolybdic acid (H3[PMo)2] 12 O 40 ]) and phosphotungstic acid (H3[PW) 12 O 40 At least one of the following: ])

[0039] In some embodiments, the surface roughness Rz of the hole-modified layer 10 is less than 2 nm.

[0040] Understandably, blending SAMs with POMs can alleviate SAMs aggregation, resulting in a significantly reduced surface roughness Rz in the prepared hole-modified layer 10. This, in turn, improves the uniformity of perovskite film formation when preparing the perovskite layer 11 on the surface of the hole-modified layer 10. The surface roughness Rz of the hole-modified layer 10 prepared using only SAMs is typically above 6 nm.

[0041] In some embodiments, the solar cell includes at least one of perovskite solar cells, perovskite / silicon tandem cells, and perovskite / perovskite tandem cells.

[0042] In some embodiments, the light-absorbing layer is a perovskite layer 11, which comprises a material having the following general chemical formula: ABY3, wherein A is selected from F. + MA + Cs + and Rb + At least one of them, B is selected from Pb 2+ Sn 2+ and Sr 2+ At least one of them, Y is selected from Cl - ,Br - and I - At least one of them.

[0043] In some embodiments, the material of the hole transport layer 9 includes at least one of metal oxide hole transport materials.

[0044] For the hole transport layer 9, which includes a metal oxide hole transport material, the self-assembled monolayer material in the hole modification layer of this application can achieve a good anchoring effect on the surface of the hole transport layer 9. The hole modification layer 10 prepared on the surface of the hole transport layer 9 has good stability, which facilitates a more uniform coverage effect of the hole modification layer on the hole transport layer, thereby reducing the problems of energy level mismatch, hole transport obstruction, and recombination aggravation caused by uneven coverage.

[0045] In some embodiments, the material of the hole transport layer 9 includes NiO. x .

[0046] The material for hole transport layer 9 includes NiO. x In a solar cell with a perovskite layer 11 as the light-absorbing layer, the self-assembled monolayer material in the hole-modifying layer can achieve a good anchoring effect on the surface of the hole transport layer 9. Simultaneously, the polyoxometalate also possesses a suitable band structure, with its conduction band located between the perovskite material and NiO. x Therefore, the hole modification layer 10 enables better energy level matching between the perovskite layer 11, the hole modification layer 10, and the hole transport layer 9, thereby improving the hole extraction capability of the hole transport layer 9.

[0047] In some embodiments, the solar cell includes a transparent conductive layer, a hole transport layer 9, a hole modification layer 10, a perovskite layer 11, an electron transport layer 14, and a metal electrode, which are stacked sequentially.

[0048] Refer again Figure 1 As shown, in some embodiments, the solar cell includes a bottom cell structure, a carrier recombination layer 8, a hole transport layer 9, a hole modification layer 10, a perovskite layer 11, an electron transport layer 14, and a top electrode 16, which are stacked sequentially.

[0049] In some embodiments, the solar cell further includes a passivation layer 12 disposed between the perovskite layer 11 and the electron transport layer 14.

[0050] In some embodiments, the solar cell further includes an electron modification layer 13 disposed between the perovskite layer 11 and the electron transport layer 14.

[0051] In some embodiments, the solar cell further includes a second transparent conductive layer 15 disposed between the electron transport layer 14 and the top electrode 16.

[0052] In some embodiments, the bottom cell structure includes a bottom electrode 1, a first transparent conductive layer 2, a first doped silicon layer 3, a first intrinsic silicon layer 4, a silicon substrate 5, a second intrinsic silicon layer 6, and a second doped silicon layer 7, which are stacked sequentially. A carrier recombination layer 8 is disposed on the surface of the second doped silicon layer 7 away from the silicon substrate 5. The doping types of the first doped silicon layer 3 and the second doped silicon layer 7 are opposite.

[0053] In some embodiments, the material of each transparent conductive layer independently includes at least one of ITO, IZO, IWO, ICO, and AZO.

[0054] In some embodiments, the material of the charge carrier composite layer 8 includes at least one of ITO, IZO, IWO, ICO, and AZO.

[0055] In some embodiments, the material of the electron transport layer 14 includes at least one of SnO2, TiO2, ZnO, and In2O3.

[0056] In some embodiments, the material of the electronic modification layer 13 includes at least one of fullerene and its derivatives.

[0057] In some embodiments, the material of the passivation layer 12 includes LiF.

[0058] Another embodiment of this application provides a method for fabricating a solar cell, comprising the following steps:

[0059] A hole modification layer 10 is prepared on the surface of the hole transport layer 9. The material of the hole modification layer 10 includes at least one of self-assembled monolayer materials and at least one of polyoxometalates.

[0060] A light-absorbing layer is prepared on the surface of the hole-modified layer 10.

[0061] In some embodiments, the method for preparing the hole-modified layer 10 includes the following steps:

[0062] A mixed solution is obtained by mixing self-assembled monolayer materials and polyoxometalates in a solvent;

[0063] The mixed solution is coated onto the surface of the hole transport layer 9 and then annealed to obtain the hole modification layer 10.

[0064] In some embodiments, the solvent includes at least one of ethanol and isopropanol.

[0065] In some embodiments, the average particle size of the self-assembled monolayer material and polyoxometalates in the mixed solution is 100 nm to 150 nm.

[0066] It is understood that the average particle size here refers to the common average particle size of the mixed solute composed of self-assembled monolayer material and polyoxometalate in the mixed solution. Blending self-assembled monolayer material with polyoxometalate can reduce the aggregation of self-assembled monolayer material in the solvent, thereby achieving a lower average particle size. The average particle size of the self-assembled monolayer material in the solution is typically above 500 nm. Optionally, the average particle size of the self-assembled monolayer material and polyoxometalate in the mixed solution can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm, or the average particle size of the self-assembled monolayer material and polyoxometalate in the mixed solution can also be within the range of any two of the above average particle sizes.

[0067] In some implementations, the annealing process takes 8 to 30 minutes.

[0068] Optionally, the annealing time can be 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min or 30 min, or the annealing time can be within any two of the above times.

[0069] In some embodiments, the annealing temperature is 80°C to 120°C.

[0070] Optionally, the annealing temperature is 80°C, 90°C, 100°C, 110°C or 120°C, or the annealing temperature may be within any two of the above temperatures.

[0071] In some embodiments, the method for fabricating a solar cell includes the following steps:

[0072] Provide silicon-based solar cells;

[0073] A hole transport layer 9 is prepared on the surface of the carrier recombination layer 8 of a silicon-based solar cell;

[0074] A mixed solution is obtained by mixing self-assembled monolayer materials and polyoxometalates in a solvent;

[0075] The mixed solution was coated on the surface of the hole transport layer 9 and then annealed to prepare the hole modification layer 10.

[0076] A perovskite layer 11 is prepared on the surface of the hole-modified layer 10;

[0077] A passivation layer 12, an electron modification layer 13, and an electron transport layer 14 are sequentially stacked on the surface of the perovskite layer 11.

[0078] A second transparent conductive layer 15 is prepared on the surface of the electron transport layer 14;

[0079] A top electrode 16 is fabricated on the surface of the second transparent conductive layer 15, and a bottom electrode 1 is fabricated on the surface of the silicon substrate cell away from the hole transport layer 9.

[0080] The following are specific embodiments.

[0081] Example 1

[0082] Methods for manufacturing solar cells:

[0083] (1) Weigh MeO-2PACz and phosphomolybdic acid at a mass ratio of 1:0.1, dissolve them in ethanol, and mix them at 800 rpm for 30 min at room temperature to obtain a mixed solution.

[0084] (2) Take a commercial-grade silicon substrate cell with a thickness of 150 μm and heat it on a heating stage at 150 °C for 15 min to activate the silicon substrate cell.

[0085] (3) The activated silicon substrate cell was placed on the carrier plate of the magnetron sputtering equipment, and the hole transport layer 9 was prepared by sputtering. The magnetron sputtering used NiO with a content of 99.99%. X The rotating target and magnetron sputtering process have a pressure of 0.52 Pa and a process atmosphere of Ar:O2 = 700 sccm:5 sccm. The hole transport layer 9 has a thickness of 22 nm.

[0086] (4) Use a pipette to pick up 100 μL of the mixed solution and spin coat it onto the hole transport layer 9 at a speed of 4000 rpm for 30 s with an acceleration of 2000 rpm / s. Then anneal at 100 °C for 10 min.

[0087] (5) The battery cell with hole modification layer 10 is placed in the evaporation equipment for co-evaporation of PbI2+CsBr to prepare lead skeleton.

[0088] (6) Weigh 300 mg of FAI, 70 mg of MABr and 40 mg of MACl, dissolve them in 5 mL of ethanol to prepare a cationic solution, and use a pipette to spin-coat 100 µL of the cationic solution onto the lead skeleton. The spin-coating conditions are: spin-coating speed of 4000 rpm, acceleration of 4000 rpm / s, spin-coating time of 30 s, and then anneal at 135 °C for 30 min.

[0089] (7) Passivation layer 12LiF and electron modification layer 13C are deposited in a metal electrode evaporation apparatus. 60 The LiF and C60 films were deposited sequentially at a rate of <0.5 Å / s, with thicknesses of 1 nm and 25 nm, respectively.

[0090] (8) Place the battery cell obtained in step (7) into the ALD device and perform chemical deposition of SnO2. The process temperature is 80℃ and the process time is 40min. The thickness of the electron transport layer 14 is 18nm.

[0091] (9) After the ALD process is completed, the second transparent conductive layer 15 is sputtered in the PVD equipment to obtain an IZO layer with a thickness of 100 nm.

[0092] (10) The front and back silver electrodes are vapor-deposited in the coating equipment. The thickness of the front electrode is 200 nm and the thickness of the back electrode is 150 nm.

[0093] (11) A LiF antireflection layer was deposited in a metal electrode coating equipment with a film thickness of 160 nm.

[0094] Example 2

[0095] The preparation method of the solar cell in Example 2 is basically the same as that in Example 1. The only difference is that the mass ratio of MeO-2PACz to phosphomolybdic acid in Example 2 is 1:0.15.

[0096] Example 3

[0097] The preparation method of the solar cell in Example 3 is basically the same as that in Example 1. The only difference is that the mass ratio of MeO-2PACz to phosphomolybdic acid in Example 3 is 1:0.2.

[0098] Example 4

[0099] The preparation method of the solar cell in Example 4 is basically the same as that in Example 1, except that the mass ratio of MeO-2PACz to phosphomolybdic acid in Example 4 is 1:0.25.

[0100] Example 5

[0101] The preparation method of the solar cell in Example 5 is basically the same as that in Example 1, except that the mass ratio of MeO-2PACz to phosphomolybdic acid in Example 5 is 1:0.3.

[0102] Example 6

[0103] The preparation method of the solar cell in Example 6 is basically the same as that in Example 3, except that the polyoxometalate in Example 6 is phosphotungstic acid.

[0104] Example 7

[0105] The preparation method of the solar cell in Example 7 is basically the same as that in Example 3, except that the self-assembled monolayer material in Example 7 is 2PACz.

[0106] Example 8

[0107] The preparation method of the solar cell in Example 8 is basically the same as that in Example 3, except that the self-assembled monolayer material in Example 8 is Me-4PACz.

[0108] Comparative Example 1

[0109] The preparation method of the solar cell in Comparative Example 1 is basically the same as that in Example 1, except that the hole modification layer 10 is prepared using only MeO-2PACz solution in Comparative Example 1.

[0110] Comparative Example 2

[0111] The preparation method of the solar cell in Comparative Example 2 is basically the same as that in Example 1. The only difference is that in Comparative Example 2, only phosphomolybdic acid solution is used to prepare the hole modification layer 10.

[0112] The solar cells in Examples 1-8 and Comparative Examples 1-2 were tested, and the test results are shown in the table below:

[0113]

[0114] The test results above show that the hole modification layer 10 prepared in Examples 1-8 comprises a self-assembled monolayer material and a polyoxometalate tandem solar cell. Compared with the tandem solar cells in Comparative Examples 1 and 2 that only use self-assembled monolayer materials or polyoxometalates as the hole modification layer 10, these cells achieve higher open-circuit voltage and conversion efficiency. In Example 3, the mass ratio of MeO-2PACz to phosphomolybdic acid is 1:0.2, which achieves higher fill factor, open-circuit voltage, and conversion efficiency compared to other examples.

[0115] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A solar cell, characterized by, The solar cell comprises a light-absorbing layer, a hole-modifying layer and a hole-transporting layer arranged in a stack; the hole-modifying layer is located between the light-absorbing layer and the hole-transporting layer; the material of the hole-modifying layer comprises at least one of a self-assembled monolayer material and at least one of a polyoxometalate.

2. The solar cell according to claim 1, characterized in that, In the hole-modifying layer, the mass ratio of the self-assembled monolayer material to the polyoxometalate is 1: (0.1-0.3).

3. The solar cell according to claim 1, characterized in that, The self-assembled monolayer material comprises at least one of 2PACz, MeO-PACz and Me-4PACz.

4. The solar cell according to claim 1, characterized in that, The polyoxometalate includes at least one of XM 12 O 40 , X2M 18 O 62 , XM6O 24 , XM9O 32 , and XM 12 O 42 , wherein X is selected from at least one of P, Si, and As, and M is selected from at least one of Mo 6+ , W 6+ , and V 5+ .

5. The solar cell according to claim 4, characterized in that, The polyoxometalate comprises at least one of phosphomolybdic acid and phosphotungstic acid.

6. The solar cell according to claim 1, characterized in that, The surface roughness Rz of the hole-modifying layer is less than 2 nm.

7. The solar cell according to any one of claims 1 to 6, wherein The solar cell comprises at least one of a perovskite solar cell, a perovskite / silicon-based stacked cell and a perovskite / perovskite stacked cell.

8. The solar cell according to any one of claims 1 to 6, wherein The light-absorbing layer is a perovskite layer, the perovskite layer comprising a material having a general chemical formula of ABY3, wherein A is selected from at least one of FA + , MA + , Cs + , and Rb + , B is selected from at least one of Pb 2+ , Sn 2+ , and Sr 2+ , and Y is selected from at least one of Cl - , Br - , and I - ; and / or, The material of the hole-transporting layer comprises at least one of a metal oxide hole-transporting material.

9. A method of producing a solar cell, characterized by, The method comprises the following steps: Preparation of a hole-modifying layer on the surface of a hole-transporting layer, wherein the material of the hole-modifying layer comprises at least one of a self-assembled monolayer material and at least one of a polyoxometalate; Preparation of a light-absorbing layer on the surface of the hole-modifying layer.

10. The method for manufacturing a solar cell according to claim 9, wherein The preparation method of the hole-modifying layer comprises the following steps: Mixing the self-assembled monolayer material and the polyoxometalate in a solvent to obtain a mixed solution; Coating the mixed solution on the surface of the hole-transporting layer and performing annealing treatment to obtain the hole-modifying layer.

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