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

Abstract

The invention discloses a solar cell and a preparation method thereof, a photovoltaic module and a photovoltaic system, and relates to the technical field of photovoltaic.The solar cell comprises a narrow-band-gap perovskite cell and a wide-band-gap perovskite cell which are sequentially stacked, the narrow-band-gap perovskite cell comprises a first hole transport layer, a first perovskite layer and a first electron transport layer which are sequentially stacked, and the wide-band-gap perovskite cell comprises a second hole transport layer, a second perovskite layer and a second electron transport layer which are sequentially stacked in the direction away from the narrow-band-gap perovskite cell. One side, facing the broadband gap perovskite cell, of the first electron transport layer is provided with a first composite layer and an edge structure arranged in the circumferential direction of the first composite layer, and a gap exists between the inner wall of the edge structure and the outer wall of the composite layer, so that the solar cell is good in cell performance.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and more specifically, to solar cells, their preparation methods, photovoltaic modules, and photovoltaic systems. Background Art

[0002] With the development of photovoltaic technology, the efficiency of current single-junction devices is gradually approaching the Shockley-Queisser efficiency limit. To break through this limit, perovskite-based tandem solar cells are an effective method. Currently, the main research directions of perovskite-based tandem solar cells are double-junction solar cells such as perovskite / Si and perovskite / perovskite, and perovskite / perovskite / Si triple-junction devices. However, when preparing the top perovskite thin film in a double-junction device or a triple-junction device, due to the steps on the substrate and the relatively thin thickness of the wide-bandgap thin film, it is difficult to prepare a perovskite thin film with good coverage and no holes, thereby affecting the performance and stability of the device. Summary of the Invention

[0003] In a first aspect of the present application, a solar cell is proposed, which includes a narrow-bandgap perovskite cell and a wide-bandgap perovskite cell stacked in sequence. The narrow-bandgap perovskite cell includes a first hole transport layer, a first perovskite layer, and a first electron transport layer stacked in sequence. The wide-bandgap perovskite cell includes a second hole transport layer, a second perovskite layer, and a second electron transport layer stacked in sequence along the direction away from the narrow-bandgap perovskite cell; a first composite layer is provided on one side of the first electron transport layer facing the wide-bandgap perovskite cell, and an edge structure is provided on the circumference of the first composite layer, and there is a gap between the inner wall of the edge structure and the outer wall of the first composite layer.

[0004] Thus, by using the solar cell of the present application, the area of the first composite layer is smaller than that of the first transport layer, avoiding the lateral transport of charges and reducing the occurrence of non-radiative recombination. In addition, an edge structure is provided circumferentially on the first composite layer, which can reduce the probability of the solution containing perovskite leaving the first electron transport layer under the action of centrifugal force after being spin-coated on one side of the first electron transport layer, playing a blocking role and increasing the residence time (liquid retention ability) of the perovskite solution on the first transport layer, which can improve the film-forming quality of the second perovskite layer, and further improve the performance and stability of the solar cell.

[0005] In some embodiments, the distance between the inner wall of the edge structure and the outer wall of the first composite layer is 100 μm - 2000 μm.

[0006] In some embodiments, the cross-section of the edge structure is axially symmetrically arranged.

[0007] In some embodiments, the edge structure includes a plurality of sub-structures arranged at intervals, and the distances between the sub-structures are equal.

[0008] In some embodiments, the thickness of the first composite layer is 10 nm - 20 nm.

[0009] In some embodiments, the thickness of the edge structure is 10 nm - 20 nm.

[0010] In some embodiments, the thickness of the first perovskite layer is 600 nm - 1200 nm.

[0011] In some embodiments, the band gap of the first perovskite layer is 1.3 eV - 1.60 eV.

[0012] In some embodiments, the first perovskite layer comprises (FA a1 MA (1-a1) ) b1 Cs (1-b1) Pb(I c1 Br (1-c1) ) 3 , where the range of a1 is 0.9 - 1, the range of b1 is 0.9 - 1, and the range of c1 is 0.95 - 1. For example, (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 ) 3 , (FA 0.95 MA 0.05 ) 0.97 Cs 0.03 Pb(I 0.98 Br 0.02 ) 3 , (FA 0.95 MA 0.05 ) 0.95 Cs 0.05 PbI 3 , FA 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 ) 3 and at least one of the following.

[0013] In some embodiments, the thickness of the second perovskite layer is 300 nm - 500 nm.

[0014] In some embodiments, the band gap of the second perovskite layer is 1.60 eV - 2.5 eV.

[0015] In some embodiments, the second perovskite layer comprises FA a2 Cs (1-a2) Pb(I b2 Br(1-b2) ) 3 , wherein the range of a2 is 0.5 - 0.9, and the range of b2 is 0.3 - 0.9; for example, the second perovskite layer includes FA 0.7 Cs 0.3 Pb(I 0.34 Br 0.66 ) 3 , FA 0.7 MA 0.1 Cs 0.2 Pb(I 0.4 Br 0.6 ) 3 , FA 0.65 MA 0.15 Cs 0.2 Pb(I 0.4 Br 0.6 ) 3 , FA 0.7 Cs 0.3 Pb(I 0.333 Br 0.667 ) 3 , FA 0.7 Cs 0.3 Pb(I 0.4 Br 0.6 ) 3 , FA 0.75 Cs 0.25 Pb(I 0.367 Br 0.633 ) 3 . At least one of the above.

[0016] In some embodiments, a first electrode is provided on a side of the wide-bandgap perovskite cell facing away from the narrow-bandgap perovskite cell, and a projected area of the first electrode on the first electron transport layer is greater than or equal to a projected area of the first composite layer on the first electron transport layer.

[0017] In some embodiments, the solar cell is a triple-junction device, and further includes a silicon bottom cell provided on a side of the narrow-bandgap perovskite cell facing away from the wide-bandgap perovskite cell, and a second composite layer is provided between the silicon bottom cell and the narrow-bandgap perovskite cell.

[0018] In some embodiments, the thickness of the second composite layer is 15 nm - 30 nm.

[0019] In some embodiments, a second electrode is provided on a side of the silicon bottom cell facing away from the narrow-bandgap perovskite cell, and a projected area of the second electrode on the silicon bottom cell is greater than or equal to a projected area of the second composite layer on the silicon bottom cell.

[0020] In a second aspect of the present application, a method for preparing the solar cell described in the first aspect is proposed, including: sequentially preparing a first hole transport layer, a first perovskite layer, and a first electron transport layer to obtain a narrow-bandgap perovskite cell; on a side of the first electron transport layer facing the wide-bandgap perovskite cell, preparing a first composite layer and preparing an edge structure in the circumferential direction of the first composite layer so that there is a gap between the inner wall of the edge structure and the outer wall of the first composite layer; on a side of the composite layer facing away from the narrow-bandgap perovskite cell, sequentially stacking a second hole transport layer, a second perovskite layer, and a second electron transport layer to obtain a wide-bandgap perovskite cell, thereby obtaining a solar cell. Thus, by using the above method, the prepared solar cell has excellent performance.

[0021] In some embodiments, the first perovskite layer is prepared by the following method: dissolving a perovskite with a bandgap width of 1.3 eV - 1.60 eV in a solvent to form a first mixed solution, on one side of the first hole transport layer, spin-coating the first mixed solution at a rotation speed of 1000 rpm - 2500 rpm for 10 s - 35 s, then spin-coating at a rotation speed of 4000 rpm - 6000 rpm for 20 s - 50 s, and before the end of spin-coating, adding chlorobenzene to the first mixed solution and annealing to obtain the first perovskite layer.

[0022] In some embodiments, the second perovskite layer is prepared by the following method: dissolving a perovskite with a bandgap width of 1.60 eV - 2.5 eV in a solvent to form a second mixed solution, on a side of the second hole transport layer facing away from the narrow-bandgap perovskite cell, spin-coating the second mixed solution at a rotation speed of 600 rpm - 2000 rpm for 10 s - 20 s, then spin-coating at a rotation speed of 3000 rpm - 6000 rpm for 30 s - 50 s, and before the end of spin-coating, adding anisole to the second mixed solution and annealing to obtain the first perovskite layer.

[0023] In a third aspect of the present application, a photovoltaic module is proposed, including at least one battery string, and the battery string includes at least two of the aforementioned solar cells.

[0024] In a fourth aspect of the present application, a photovoltaic system is proposed, including the aforementioned photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0026] Figure 1 is a structural diagram of the solar cell according to an embodiment of the present application;

[0027] Figure 2 is Figure 1Partial structural schematic diagram in;

[0028] Figure 3 Flow chart of the preparation method of the solar cell according to the embodiment of the present application;

[0029] Figure 4 Morphology diagrams of the second perovskite layer prepared in Example 1 and Comparative Example 1 of the present application;

[0030] Figure 5 Current density-voltage curve diagrams of the solar cells prepared in Example 1 and Comparative Example 1 of the present application.

[0031] Explanation of reference numerals:

[0032] 100, narrow-bandgap perovskite cell; 200, wide-bandgap perovskite cell; 300, silicon bottom cell; 01, second electrode; 02, third hole transport layer; 03, bottom cell material layer; 04, third electron transport layer; 05, second composite layer; 06, first hole transport layer; 07, first perovskite layer; 08, first electron transport layer; 09, first composite layer, 10, second hole transport layer; 11, second perovskite layer; 12, second electron transport layer; 13, first electrode; 14, edge structure. Detailed implementation manners

[0033] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the drawings, but there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0034] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the art belonging to the technical field of the present application; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; unless otherwise stated, the numerical values of the various parameters mentioned in the present application can be measured by various commonly used measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of the present application).

[0035] The terms "comprising" and "having" and any variations thereof in the description and claims of the present application are open expressions, that is, including the content specified in the present application, but not excluding other aspects.

[0036] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "width" and "thickness" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0037] In the description of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. The "first feature" and "second feature" may include one or more of such features.

[0038] In the description of the present application, the meaning of "a plurality of" is two or more.

[0039] In the description of the present application, "A and / or B" may include the case of A alone, the case of B alone, and any one of the cases of A and B, where A and B are only for example and may be any technical features connected by "and / or" in the present application.

[0040] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0041] If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0042] With the development of photovoltaic technology, the efficiency of current single-junction devices is gradually approaching the Shockley-Queisser efficiency limit. To break through this limit, perovskite-based tandem solar cells are an effective method. Currently, the main research directions of perovskite-based tandem solar cells are double-junction solar cells such as perovskite / Si and perovskite / perovskite, and perovskite / perovskite / Si triple-junction devices. However, when preparing the top perovskite thin film in a double-junction device or a triple-junction device, due to the steps on the substrate and the relatively thin thickness of the wide-bandgap thin film, it is difficult to prepare a perovskite thin film with good coverage and no holes, thereby affecting the performance and stability of the device.

[0043] In the first aspect of the present application, the present application proposes a solar cell. Refer to Figure 1, the solar cell includes a narrow-bandgap perovskite cell 100 and a wide-bandgap perovskite cell 200 stacked in sequence. The narrow-bandgap perovskite cell 100 includes a first hole transport layer 06, a first perovskite layer 07, and a first electron transport layer 08 stacked in sequence. The wide-bandgap perovskite cell 200 includes a second hole transport layer 10, a second perovskite layer 11, and a second electron transport layer 12 stacked in sequence along the direction away from the narrow-bandgap perovskite cell 100. A first composite layer 09 is provided on one side of the first electron transport layer 08 facing the wide-bandgap perovskite cell 200, and an edge structure 14 is provided on the circumference of the first composite layer 09. There is a gap between the inner wall of the edge structure 14 and the outer wall of the first composite layer 09.

[0044] In this application, in the structure of the tandem cell, the area of the first composite layer 09 between the series structures is usually smaller than that of other charge transport layers or functional layers. This is mainly to avoid the lateral transport of charges and reduce the occurrence of non-radiative recombination. The smaller-area composite layer will form a step in the device, and this step will affect the film formation and crystallization of the second perovskite layer 11, especially when the thickness of the second perovskite layer 11 is small. In a perovskite / perovskite / silicon triple-junction device or a perovskite / perovskite double-junction device, due to the thin thickness of the perovskite layer (the second perovskite layer 11) of the top cell, the step formed by the first composite layer 09 between the perovskites will seriously affect the film formation and crystallization of the top second perovskite layer 11. By structurally designing the first composite layer 09 between the perovskites in the triple-junction device or the double-junction device and using the edge structure 14, the present invention can effectively improve the film formation quality of the second perovskite layer 11 in the wide-bandgap perovskite cell 200 and can effectively improve the film formation quality of the top cell (the wide-bandgap perovskite cell 200) and the performance of the triple-junction or double-junction device.

[0045] It can be understood that a perovskite / perovskite / silicon triple-junction device refers to a battery with perovskite materials of different bandgaps in the top and middle layers and a silicon-based absorption layer structure in the bottom layer. A perovskite / perovskite double-junction device is a tandem solar cell based on perovskite materials, consisting of two perovskite materials with different bandgaps. By reasonably designing the bandgaps, more efficient light absorption and charge separation can be achieved.

[0046] It can be understood that, taking the preparation of the second perovskite layer 11 by spin coating as an example, since the thickness of the second hole transport layer 10 is relatively thin, after the first composite layer 09 and the second hole transport layer 10 are respectively prepared on one side of the narrow-bandgap perovskite solar cell 100, the step is still obvious, which will affect the film-forming quality of the second perovskite layer 11. The existence of the edge structure 14 can reduce the probability that the solution containing perovskite before spin-coating on one side of the first electron transport layer 08 leaves the first electron transport layer 08 under the action of centrifugal force. The edge structure 14 plays a blocking role and improves the residence time (liquid retention ability) of the perovskite solution on the first transport layer, which can improve the film-forming quality of the second perovskite layer 11.

[0047] It can be understood that the present application does not limit the specific form of the edge structure 14. As long as the edge structure 14 is provided on the circumference of the composite layer and there is a gap between the edge structure 14 and the composite layer, it is within the protection scope of the present application.

[0048] As an example, Figure 2 for the present application Figure 1 is a schematic three-dimensional structure diagram of the first electron transport layer 08, the first composite layer 09 and the edge structure 14 in the present application. Figure 2 Three forms of the edge structure 14 are given in the figure, but the present application is not limited thereto. The morphology of the edge structure 14 is preferably a regular morphology (for example Figure 2 the three forms), so as to facilitate the preparation of the above-mentioned edge structure 14 by using a mask plate.

[0049] In some embodiments, the distance between the inner wall of the edge structure 14 and the outer wall of the first composite layer 09 is 100 μm - 2000 μm; for example, it can be 100 μm, 500 μm, 1000 μm, 1500 μm, 2000 μm, etc. Controlling the distance between the two within the above range can further improve the film-forming quality of the formed second perovskite layer 11, and thus improve the performance and stability of the solar cell.

[0050] In some embodiments, the cross-section of the edge structure 14 is axially symmetrically arranged. Thus, the edge structure 14 has a regular morphology. On the one hand, it is convenient to prepare the above-mentioned edge structure 14 by using a mask plate. On the other hand, after the solution before perovskite is spin-coated on one side of the first electron transport layer 08, the blocking effect of the edge structure 14 is relatively uniform, which can further improve the film-forming quality of the second perovskite layer 11, and thus improve the performance and stability of the solar cell.

[0051] In some embodiments, the edge structure 14 includes a plurality of sub-structures arranged at intervals, and the distances between the sub-structures are equal. Thus, the edge structure 14 is convenient to be prepared by using a mask plate, and can save materials and has a good blocking effect.

[0052] In some embodiments, please refer toFigure 1 , the solar cell is a triple-junction device, and further includes a silicon bottom cell 300 disposed on a side of the narrow-bandgap perovskite cell 100 away from the wide-bandgap perovskite cell 200. A projected area of the first composite layer 09 on the silicon bottom cell 300 is S1, and a projected area of any one of the first hole transport layer 06, the first perovskite layer 07, and the first electron transport layer 08 on the silicon bottom cell 300 is S2, where S1 / S2 = 0.2 - 0.8. For example, S1 / S2 can be 0.2, 0.4, 0.5, 0.7, 0.8, etc. Controlling the ratio of the projected area of the first composite layer 09 on the silicon bottom cell 300 to the projected area of other transport layers within the above range can further avoid the lateral transport of charges, reduce the occurrence of non-radiative recombination, and thereby improve the performance of the solar cell.

[0053] In addition, the triple-junction solar cell provided by the present invention (the wide-bandgap perovskite cell 200 absorbs sunlight in the short-wave band, allowing sunlight in other bands to pass through; the narrow-bandgap perovskite cell 100 absorbs sunlight in the band between the short wave and the long wave and allows long-wave sunlight to pass through; the silicon bottom cell 300 is used to absorb long-wave sunlight) makes full use of the solar spectrum and improves the conversion efficiency of the solar cell.

[0054] In some embodiments, the thickness of the first composite layer 09 is 10 nm - 20 nm. For example, the thickness of the first composite layer 09 can be 10 nm, 13 nm, 15 nm, 17 nm, 20 nm, etc. Controlling the thickness of the first composite layer 09 within the above range can further avoid the lateral transport of charges, reduce the occurrence of non-radiative recombination, and at the same time has good light transmittance and carrier transport effect.

[0055] In some embodiments, the material of the first composite layer 09 includes a transparent conductive oxide, and the transparent conductive oxide includes at least one of indium tin oxide, fluorine-doped tin dioxide, and indium zinc oxide. The above transparent conductive oxide can avoid the lateral transport of charges, reduce the occurrence of non-radiative recombination, and at the same time has good light transmittance and carrier transport effect.

[0056] In some embodiments, the thickness of the edge structure 14 is 10 nm - 20 nm. For example, it can be 10 nm, 13 nm, 15 nm, 17 nm, 20 nm, etc. Controlling the thickness of the edge structure 14 within the above range can better improve the film-forming quality of the second perovskite layer 11, and can effectively improve the film-forming quality of the top cell (wide-bandgap perovskite cell 200) and the performance of the triple-junction or double-junction device.

[0057] In some embodiments, the material of the edge structure 14 includes a transparent conductive oxide, and the transparent conductive oxide includes at least one of indium tin oxide, fluorine-doped tin dioxide, and indium zinc oxide. The above-mentioned transparent conductive oxide can improve the film-forming quality of the second perovskite layer 11 and has good light transmittance and carrier transport effect.

[0058] In some embodiments, the thickness of the first perovskite layer 07 is 600 nm - 1200 nm. For example, it can be 600 nm, 800 nm, 1000 nm, 1200 nm, etc., which can improve the utilization of light, improve the photoelectric conversion efficiency of the perovskite battery, and improve the efficiency of the solar cell.

[0059] In some embodiments, the bandgap of the first perovskite layer 07 is 1.3 eV - 1.60 eV. For example, it can be 1.3 eV, 1.4 eV, 1.5 eV, 1.6 eV, etc. By controlling the bandgap of the first perovskite layer 07 within the above range, the bandgap is relatively narrow, which can greatly broaden the absorption spectrum range of the solar cell and improve the solar energy conversion efficiency.

[0060] In some embodiments, the first perovskite layer 07 includes (FA a1 MA (1-a1) ) b1 Cs (1-b1) Pb(I c1 Br (1-c1) ) 3 , where the range of a1 is 0.9 - 1, the range of b1 is 0.9 - 1, and the range of c1 is 0.95 - 1. As an example, a1 can be 0.9, 0.95, 1, etc., b1 can be 0.9, 0.95, 1, etc., and c1 can be 0.95, 0.97, 1, etc. For example, the first perovskite layer 07 includes FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 ) 3 , (FA 0.95 MA 0.05 ) 0.97 Cs 0.03 Pb(I 0.98 Br 0.02 ) 3 , (FA 0.95 MA 0.05 ) 0.95 Cs 0.05 PbI 3 , FA 0.95 Cs 0.05 Pb(I 0.98 Br 0.02) 3 at least one of the above. The perovskite has a narrow bandgap, which can greatly broaden the absorption spectrum range of the solar cell and improve the solar energy conversion efficiency.

[0061] In some embodiments, the thickness of the second perovskite layer 11 is 300 nm - 500 nm. For example, it can be 300 nm, 400 nm, 500 nm, etc. Controlling the thickness of the second perovskite layer 11 within the above range can improve the utilization of light, improve the photoelectric conversion efficiency of the perovskite battery, and improve the efficiency of the solar cell 100.

[0062] In some embodiments, the bandgap of the second perovskite layer 11 is 1.60 eV - 2.5 eV. For example, it can be 1.60 eV, 1.8 eV, 2 eV, 2.3 eV, 2.5 eV, etc. Controlling the bandgap of the second perovskite layer 11 within the above range, with a relatively wide bandgap, can greatly broaden the absorption spectrum range of the solar cell and improve the solar energy conversion efficiency.

[0063] In some embodiments, the second perovskite layer 11 includes FA a2 Cs (1-a2) Pb(I b2 Br (1-b2) ) 3 , where the range of a2 is 0.5 - 0.9 and the range of b2 is 0.3 - 0.9; as an example, a2 can be 0.5, 0.7, 0.9, etc., and b2 can be 0.3, 0.5, 0.7, 0.9, etc. For example, the second perovskite layer 11 includes FA 0.7 Cs 0.3 Pb(I 0.34 Br 0.66 ) 3 , FA 0.7 MA 0.1 Cs 0.2 Pb(I 0.4 Br 0.6 ) 3 , FA 0.65 MA 0.15 Cs 0.2 Pb(I 0.4 Br 0.6 ) 3 , FA 0.7 Cs 0.3 Pb(I 0.333 Br 0.667 ) 3 , FA 0.7 Cs 0.3 Pb(I 0.4 Br 0.6 ) 3 , FA 0.75Cs 0.25 Pb(I 0.367 Br 0.633 ) 3 At least one of the above, the perovskite has a wide bandgap, which can greatly broaden the absorption spectrum range of the solar cell and improve the solar energy conversion efficiency.

[0064] In some embodiments, referring to Figure 1 , a first electrode 13 is provided on a side of the wide-bandgap perovskite cell 200 facing away from the narrow-bandgap perovskite cell 100, and a projected area of the first electrode 13 on the first electron transport layer 08 is greater than or equal to a projected area of the first composite layer 09 on the first electron transport layer 08. Thus, lateral transport of charges can be avoided, and the occurrence of non-radiative recombination can be reduced.

[0065] In some embodiments, referring to Figure 1 , the solar cell is a triple-junction device, and further includes a silicon bottom cell 300 provided on a side of the narrow-bandgap perovskite cell 100 facing away from the wide-bandgap perovskite cell 200. A second composite layer 05 is provided between the silicon bottom cell 300 and the narrow-bandgap perovskite cell 100. The second composite layer 05 has good light transmittance and carrier transport function, and can avoid lateral transport of charges, reduce the occurrence of non-radiative recombination, and thereby improve the performance of the solar cell.

[0066] In some embodiments, a projected area of the second composite layer 05 on the silicon bottom cell 300 is smaller than a projected area of any one of the first hole transport layer 06, the first perovskite layer 07, and the first electron transport layer 08 on the silicon bottom cell 300. Thus, lateral transport of charges can be further avoided, the occurrence of non-radiative recombination can be reduced, and thereby the performance of the solar cell can be improved.

[0067] In some embodiments, similar to the circumferential structure of the first composite layer 09, the circumference of the second composite layer 05 can also be provided with a first edge structure having a gap around it, so as to effectively improve the film-forming quality of the first perovskite layer 07 in the narrow-bandgap perovskite cell 100 when the first perovskite layer 07 is prepared, and can effectively improve the film-forming quality of the narrow-bandgap perovskite cell 100 and the performance of the triple-junction or double-junction device.

[0068] In some embodiments, the projected area of the second composite layer 05 on the silicon bottom cell 300 is S3, and the projected area of any one of the first hole transport layer 06, the first perovskite layer 07, and the first electron transport layer 08 on the silicon bottom cell 300 is S2, where S3 / S2 = 0.2 - 0.8. For example, it can be 0.2, 0.5, 0.8, etc. Controlling the ratio of the projected area of the second composite layer 05 on the silicon bottom cell 300 to the projected area of other transport layers within the above range can further avoid the lateral transport of charges, reduce the occurrence of non-radiative recombination, and thus improve the performance of the solar cell.

[0069] In some embodiments, the thickness of the second composite layer 05 is 15 - 30 nm; for example, it can be 15 nm, 20 nm, 30 nm, etc. Controlling the thickness of the second composite layer 05 within the above range can further avoid the lateral transport of charges, reduce the occurrence of non-radiative recombination, and at the same time have good light transmittance and carrier transport function.

[0070] In some embodiments, the second composite layer 05 includes a transparent conductive oxide, and the transparent conductive oxide includes at least one of indium tin oxide, fluorine-doped tin dioxide, and indium zinc oxide. The above transparent conductive oxide can avoid the lateral transport of charges, reduce the occurrence of non-radiative recombination, and at the same time have good light transmittance and carrier transport function.

[0071] In some embodiments, a second electrode 01 is provided on the side of the silicon bottom cell 300 facing away from the narrow-bandgap perovskite cell 100, and the projected area of the second electrode 01 on the silicon bottom cell 300 is greater than or equal to the projected area of the second composite layer 05 on the silicon bottom cell 300. In this way, the lateral transport of charges can be avoided, and the occurrence of non-radiative recombination can be reduced.

[0072] In some embodiments, refer to Figure 1 , the silicon bottom cell 300 includes a third electron transport layer 04, a bottom cell material layer 03, and a third hole transport layer 02 stacked in sequence in the direction away from the narrow-bandgap perovskite cell 100.

[0073] In some embodiments, the materials of the first electron transport layer 08, the second electron transport layer 12, and the third electron transport layer 04 independently include, but are not limited to, TiO 2 , SnO 2, transparent oxides such as ZnO, the thicknesses of the first electron transport layer 08, the second electron transport layer 12, and the third electron transport layer 04 are each independently 20 - 50 nm, 10 - 30 nm, 20 - 50 nm; the first hole transport layer 06, the second hole transport layer 10, and the third hole transport layer 02 each independently include but are not limited to organic small molecule materials (such as PTAA, HTM-1, HTM-2, etc.), inorganic materials (such as NiO, CuO, etc.), and the thicknesses of the first hole transport layer 06, the second hole transport layer 10, and the third hole transport layer 02 are each independently 1 - 15 nm, 1 - 25 nm, 1 - 25 nm; the material of the bottom cell material layer 03 includes but is not limited to silicon, group III-V semiconductor materials, group II-VI semiconductor materials, and perovskite, and the thickness of the bottom cell material layer 03 is 80 μm - 120 μm.

[0074] In some embodiments, the materials of the first electrode 13 and the second electrode 01 each independently include but are not limited to transparent conductive oxides (such as ITO, FTO, IZO, etc.), conductive polymers, and metal electrodes (such as Ag, Au, etc.), and the thicknesses of the first electrode 13 and the second electrode 01 are each independently 20 - 40 nm, 200 - 500 nm.

[0075] In the second aspect of the present application, the present application proposes a method for preparing the solar cell described in the first aspect. For the solar cell prepared by this method, in a perovskite / perovskite / silicon triple-junction device or a perovskite / perovskite double-junction device, due to the relatively thin thickness of the perovskite layer (the second perovskite layer 11) of the top cell, the step formed by the first composite layer 09 between perovskites will seriously affect the film formation and crystallization of the top second perovskite layer 11. By structurally designing the first composite layer 09 between perovskites in the triple-junction device or the double-junction device and using the edge structure 14, the present invention can effectively improve the film formation quality of the second perovskite layer 11 in the wide-bandgap perovskite cell 200, and can effectively improve the film formation quality of the top cell (wide-bandgap perovskite cell 200) and the performance of the triple-junction or double-junction device.

[0076] Refer to Figure 3 , the method for preparing the solar cell 100 according to the embodiment of the present application includes:

[0077] S100: sequentially prepare the first hole transport layer 06, the first perovskite layer 07, and the first electron transport layer 08 to obtain the narrow-bandgap perovskite cell 100.

[0078] In some embodiments, the solar cell is a triple-junction device, further including a silicon bottom cell 300 disposed on a side of the narrow-bandgap perovskite cell 100 away from the wide-bandgap perovskite cell 200. The silicon bottom cell 300 includes a third electron transport layer 04, a bottom cell material layer 03, and a third hole transport layer 02 sequentially stacked in a direction away from the narrow-bandgap perovskite cell 100. The preparation methods of each layer are as follows:

[0079] An n-type c-Si wafer with a bulk resistivity of 1.5 ± 0.5 Ω·cm is used as a substrate. First, the wafer is processed in a dilute KOH solution, then subjected to a standard RCA cleaning, then etched with dilute hydrofluoric acid (HF) to remove the oxide layer formed on the wafer surface, and finally the wafer is loaded into plasma-enhanced chemical vapor deposition (PECVD). During the PECVD process, an (i)a-Si:H / (n)μc-SiOx:H electron transport layer (the third electron transport layer 04) is deposited on the front side, and an (i)a-Si:H / (p)μc-Si:H hole transport layer (the third hole transport layer 02) is deposited on the other side. Subsequently, ITO conductive layers with thicknesses of 10 - 20 nm and 15 - 50 nm are respectively deposited on the front and back sides of the silicon wafer by radio frequency magnetron sputtering. Finally, a layer of silver paste screen is printed on the back side of the wafer, and the obtained cell is cured in an oven at 150 - 180 °C.

[0080] In some embodiments, the first hole transport layer 06, the first perovskite layer 07, and the first electron transport layer 08 can be prepared by conventional methods in the art. For example, the first hole transport layer 06 and the first perovskite layer 07 are prepared by spin coating, and the first electron transport layer 08 is prepared by evaporation.

[0081] In some embodiments, the first perovskite layer 07 is prepared by the following method:

[0082] S101: Dissolve a perovskite with a bandgap width of 1.3 eV - 1.60 eV in a solvent to form a first mixed solution. Spin coat the first mixed solution on one side of the first hole transport layer 06, and before the end of spin coating, add chlorobenzene to the first mixed solution, and anneal to obtain the first perovskite layer 07.

[0083] Adding chlorobenzene to the first mixed solution before the end of spin coating can be partially miscible with the precursor solvent, quickly "extract" the residual solvent, shorten the solvent evaporation time, and force the perovskite to nucleate and crystallize quickly.

[0084] In some embodiments, in the first mixed solution, the concentration of perovskite is 1.3 mol / L - 1.9 mol / L. For example, it can be 1.3 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, etc. Controlling the concentration of perovskite in the first mixed solution within the above range can effectively regulate the current distribution of the triple-junction device, and at the same time avoid introducing a large number of defects, thereby preparing a first perovskite layer 07 with better quality.

[0085] In some embodiments, the spin coating includes spin coating for 10 s - 35 s (such as 10 s, 20 s, 30 s, 35 s, etc.) at a rotation speed of 1000 rpm - 2500 rpm (for example, the rotation speed can be 1000 rpm, 2000 rpm, 2500 rpm, etc.), and then spin coating for 20 s - 50 s (such as 20 s, 30 s, 40 s, 50 s, etc.) at a rotation speed of 4000 rpm - 6000 rpm (for example, the rotation speed can be 4000 rpm, 5000 rpm, 6000 rpm, etc.). By spin coating at different rotation speeds above, first at a low rotation speed and then at a high rotation speed, a first perovskite layer 07 with better quality can be prepared.

[0086] S200: Prepare a first composite layer 09 on the side of the first electron transport layer 08 facing the wide-bandgap perovskite cell 200, and prepare an edge structure 14 in the circumferential direction of the first composite layer 09, so that there is a gap between the inner wall of the edge structure 14 and the outer wall of the first composite layer 09.

[0087] In some embodiments, the first composite layer 09 can be prepared by a conventional preparation method in the art. For example, it is prepared by evaporation.

[0088] In some embodiments, the edge structure 14 can be prepared by evaporation in combination with a mask template.

[0089] S300: Prepare a second hole transport layer 10, a second perovskite layer 11, and a second electron transport layer 12 stacked in sequence on the side of the composite layer facing away from the narrow-bandgap perovskite cell 100 to obtain a wide-bandgap perovskite cell 200, thus obtaining a solar cell.

[0090] In some embodiments, the second hole transport layer 10, the second perovskite layer 11, and the second electron transport layer 12 can be prepared by conventional methods in the art. For example, the first hole transport layer 06 is prepared by sputtering and / or spin coating, the second perovskite layer 11 is prepared by spin coating, and the second electron transport layer 12 is prepared by evaporation.

[0091] In some embodiments, the second perovskite layer 11 is prepared by the following method:

[0092] S301: Dissolve perovskite with a bandgap width of 1.60 eV - 2.5 eV in a solvent to form a second mixed solution. Spin-coat the second mixed solution on the side of the second hole transport layer 10 facing away from the narrow-bandgap perovskite solar cell 100. Before the end of spin-coating, add anisole to the second mixed solution and anneal to obtain the first perovskite layer 07.

[0093] In some embodiments, in the second mixed solution, the concentration of perovskite is 0.9 mol / L - 1.3 mol / L. For example, it can be 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.3 mol / L, etc. Controlling the concentration of perovskite in the second mixed solution within the above range can make the solution spread evenly at a low rotation speed and control the film thickness using a high rotation speed, thereby preparing a second perovskite layer 11 with better quality.

[0094] In some embodiments, the spin-coating includes spin-coating for 10 - 20 s (such as 10 s, 15 s, 20 s, etc.) at a rotation speed of 600 - 2000 rpm (such as the rotation speed can be 1600 rpm, 1000 rpm, 2000 rpm, etc.), and then spin-coating for 30 - 50 s (such as 30 s, 40 s, 50 s, etc.) at a rotation speed of 3000 - 6000 rpm (such as the rotation speed can be 3000 rpm, 5000 rpm, 6000 rpm, etc.). By spin-coating at different rotation speeds above, first at a low rotation speed and then at a high rotation speed, the current distribution of the triple-junction device can be regulated, and at the same time, good thickness uniformity can be obtained, thereby preparing a second perovskite layer 11 with better quality.

[0095] In some embodiments, the solar cell further includes a first electrode 13 and a second electrode 01, and the first electrode 13 and the second electrode 01 can be prepared by evaporation.

[0096] In summary, for the preparation method of the above-mentioned solar cell proposed in this application, in the perovskite / perovskite / silicon triple-junction device or perovskite / perovskite double-junction device, since the thickness of the perovskite layer (the second perovskite layer 11) of the top cell is relatively thin, the step formed by the first composite layer 09 between perovskite and perovskite will seriously affect the film formation and crystallization of the top second perovskite layer 11. By structurally designing the first composite layer 09 between perovskite and perovskite in the triple-junction device or double-junction device and using the edge structure 14, the film formation quality of the second perovskite layer 11 in the wide-bandgap perovskite solar cell 200 can be effectively improved, and the film formation quality of the top cell (wide-bandgap perovskite solar cell 200) and the performance of the triple-junction or double-junction device can be effectively improved.

[0097] In a third aspect of the present application, a photovoltaic module is proposed, which includes at least one battery string, and the battery string includes at least two solar cells as described in the first aspect, or solar cells prepared by the method described in the second aspect.

[0098] In some embodiments, the solar cells can be connected together by string soldering, so as to collect the electric energy generated by a single solar cell for subsequent transmission.

[0099] In some embodiments, the solar cells can be arranged at intervals or stacked in a shingled form.

[0100] Exemplarily, the photovoltaic module further includes an encapsulation layer and a cover plate. The encapsulation layer is used to cover the surface of the battery string, and the cover plate is used to cover the surface of the encapsulation layer away from the battery string.

[0101] In a fourth aspect of the present application, a photovoltaic system is proposed, which includes the aforementioned photovoltaic module.

[0102] The photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a rooftop power station, a water surface power station, etc., and can also be applied to devices or apparatuses that use solar energy for power generation, such as a user solar power supply, a solar street lamp, a solar vehicle, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields that require solar power generation. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a busbar trunking box, and an inverter. The photovoltaic array can be an array combination of multiple photovoltaic modules. For example, multiple photovoltaic modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the busbar trunking box, and the busbar trunking box can collect the current generated by the photovoltaic array. After the collected current flows through the inverter and is converted into alternating current required by the commercial power grid, it is connected to the commercial power grid to achieve solar power supply.

[0103] The solution of the present application will be described below through specific embodiments. It should be noted that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0104] Example 1

[0105] Preparation of silicon-based battery: An n-type c-Si wafer with a bulk resistivity of 1.5 ± 0.5 Ωcm is used as the substrate. First, the wafer is processed in a dilute KOH solution, then subjected to standard RCA cleaning, then etched with dilute hydrofluoric acid (HF) to remove the oxide layer formed on the wafer surface, and finally the wafer is loaded into plasma-enhanced chemical vapor deposition (PECVD). During the PECVD process, an (i)a-Si:H / (n)μc-SiOx:H electron transport layer (the third electron transport layer 04) is deposited on the front side, and an (i)a-Si:H / (p)μc-Si:H hole transport layer (the third hole transport layer 02) is deposited on the other side. Subsequently, ITO conductive layers with thicknesses of 10 - 20 nm and 15 - 50 nm are deposited on the front and back sides of the silicon wafer respectively by radio frequency magnetron sputtering technology. Finally, a layer of silver paste screen is printed on the back side of the wafer, and the obtained battery is cured in an oven at 150 - 180 °C to obtain the silicon-based battery.

[0106] 1. Irradiate the silicon-based battery under UV light for 15 minutes, then spin-coat the SAM solution (MEo-2PACz:2PACz = 3:1, total concentration of 0.5 mg / mL) at 4000 rpm for 30 seconds, and then anneal at 100 °C for 10 minutes to obtain a SAM layer with a thickness of 2 nm, obtaining the first hole transport layer with a thickness of 2 nm.

[0107] 2. Intermediate bandgap perovskite (FA 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 ) 3 ) is dissolved in a mixed solution of DMF:DMSO = 4:1 with a concentration of 1.7 mol / mL. The spin-coating parameters are 2000 rpm for 25 s and then 5000 rpm for 30 s, and 200 μL of chlorobenzene is dropped in the last 10 s, and then annealed at 100 °C for 20 minutes to obtain the first perovskite layer with a thickness of 1 μm.

[0108] 3. Sequentially evaporate the first electron transport layer (a C 60 layer with a thickness of 15 nm, a SnO 2 layer with a thickness of 30 nm) and an IZO (composite layer) with a thickness of 20 nm onto the above device. After the IZO evaporation is completed, a 20 nm layer is plated on the edge of the composite layer IZO using a mask plate, as shown in Figure 1 and Figure 2 in Figure 1. The distance between the inner wall of the edge structure and the outer wall of the first composite layer is 1000 μm.

[0109] 4. Then sputter 15 nm of NiO x, spin-coat the SAM solution (MEo-2PACz:2PACz = 3:1, total concentration 0.5 mg / mL) at 4000 rpm for 30 seconds, then anneal at 100 °C for 10 minutes to obtain a SAM layer with a thickness of 2 nm, NiO x The NiO and SAM layers form the second hole transport layer with a total thickness of 17 nm.

[0110] 5. Dissolve the wide-bandgap perovskite (FA 0.7 Cs 0.3 Pb(I 0.333 Br 0.667 ) 3 ) in a mixed solution of DMF:DMSO = 4:1 with a concentration of 1.0 mol / mL. The spin-coating parameters are 1000 rpm for 10 s then 4000 rpm for 40 s, and 160 μL of anisole is added dropwise 10 s before the end, then anneal at 100 °C for 20 minutes to obtain the second perovskite layer with a thickness of 400 nm.

[0111] 7. Evaporate the second electron transport layer (C layer with a thickness of 12 nm, SnO layer with a thickness of 15 nm), the first electrode (30 nm of IZO, 400 nm of Ag), and the antireflection film (MgF with a thickness of 110 nm) 60 layer, SnO layer with a thickness of 15 nm) 2 layer), the first electrode (30 nm of IZO, 400 nm of Ag), and the antireflection film (MgF with a thickness of 110 nm) 2 ) onto the above device to obtain a solar cell.

[0112] Example 2

[0113] The preparation process is basically the same as that of Example 1, except that the edge structure uses the ITO edge structure shown in Figure 2 Figure 2.

[0114] Example 3

[0115] The preparation process is basically the same as that of Example 1, except that the edge structure uses the ITO edge structure shown in Figure 2 Figure 3.

[0116] Comparative Example 1

[0117] The preparation process is basically the same as that of Example 1, except that the edge structure is not prepared.

[0118] The morphologies of the second perovskite layers prepared in Example 1 and Comparative Example 1 are shown in Figure 4As shown, from the perspective of the thin film morphology, after introducing an edge structure in the circumferential direction of the composite layer in Example 1, the quality of the wide-bandgap perovskite thin film (the second perovskite layer) has been greatly improved. It can be found that in Comparative Example 1, an obvious demarcation will form at the steps of the composite layer, which will lead to uneven stress distribution in the second perovskite layer, seriously affecting the film-forming quality and ultimately greatly affecting the device performance.

[0119] Following the IEC 61730 standard, the open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF (Fill Factor), and energy conversion efficiency Eff (Efficiency) of the above solar cells were tested. The test results are shown in Table 1 and Figure 5 .

[0120] Figure 5 Figure Figure 3 shows the current density-voltage curves of the perovskite cells prepared in Example 1 and Comparative Example 1. As can be seen, the performance of the solar cells in the embodiments of the present invention is significantly better than that of Comparative Example 1 in all aspects.

[0121] Table 1

[0122]

[0123] As can be seen from Table 1, in the solar cells of Embodiments 1-3 of the present application, by designing the structure of the composite layer between perovskites in the triple-junction device and using an edge structure, the film-forming quality of the second perovskite layer in the wide-bandgap perovskite cell can be effectively improved, and the film-forming quality of the top cell (wide-bandgap perovskite cell) and the performance of the triple-junction device can be effectively improved. In Comparative Example 1, without using an edge structure, the short-circuit current, open-circuit voltage, and efficiency of the solar cell are significantly reduced.

[0124] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same effect as the technical idea within the technical scope of the present application are included in the technical scope of the present application. In addition, within the scope of not departing from the gist of the present application, various modifications that can be thought of by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A solar cell, characterized in that: It comprises a narrow-bandgap perovskite cell and a wide-bandgap perovskite cell stacked in sequence, wherein the narrow-bandgap perovskite cell comprises a first hole transport layer, a first perovskite layer and a first electron transport layer stacked in sequence, and the wide-bandgap perovskite cell comprises a second hole transport layer, a second perovskite layer and a second electron transport layer stacked in sequence in a direction away from the narrow-bandgap perovskite cell; A first composite layer and an edge structure arranged around the first composite layer are provided on a side of the first electron transport layer facing the wide bandgap perovskite cell, and a gap is provided between an inner wall of the edge structure and an outer wall of the first composite layer.

2. The solar cell according to claim 1, characterized in that The distance between the inner wall of the edge structure and the outer wall of the first composite layer is 100 μm-2000 μm; and / or, The cross section of the edge structure is arranged in an axisymmetric manner; and / or, The edge structure includes a plurality of substructures arranged at intervals, and the distances between the substructures are equal.

3. The solar cell according to claim 1 or 2, characterized in that: The thickness of the first perovskite layer is 600nm-1200nm; and / or, The band gap of the first perovskite layer is 1.3 eV-1.60 eV; The thickness of the second perovskite layer is 300nm-500nm; and / or, The band gap of the second perovskite layer is 1.60 eV-2.5 eV.

4. The solar cell according to claim 1 or 2, characterized in that: The thickness of the first composite layer is 10nm-20nm; and / or, The thickness of the edge structure is 10nm-20nm; and / or, The first perovskite layer comprises (FA a1 MA (1-a1) ) b1 Cs (1-b1) Pb(I c1 Br (1-c1) )3, wherein a1 is in the range of 0.9-1, b1 is in the range of 0.9-1, and c1 is in the range of 0.95-1; and / or, The second perovskite layer includes FA a2 Cs (1-a2) Pb(I b2 Br (1-b2) )3, where a2 ranges from 0.5-0.9 and b2 ranges from 0.3-0.

9.

5. The solar cell according to claim 1 or 2, characterized in that: A first electrode is provided on a side of the wide bandgap perovskite cell facing away from the narrow bandgap perovskite cell, and a projected area of ​​the first electrode on the first electron transport layer is greater than or equal to a projected area of ​​the first composite layer on the first electron transport layer.

6. The solar cell according to claim 1 or 2, characterized in that: The solar cell is a triple-junction device and further comprises a silicon bottom cell arranged on the side of the narrow-bandgap perovskite cell away from the wide-bandgap perovskite cell, and a second composite layer is arranged between the silicon bottom cell and the narrow-bandgap perovskite cell.

7. The solar cell according to claim 6, characterized in that: The thickness of the second composite layer is 15nm-30nm; and / or, A second electrode is provided on a side of the silicon bottom cell facing away from the narrow bandgap perovskite cell, and a projection area of ​​the second electrode on the silicon bottom cell is greater than or equal to a projection area of ​​the second composite layer on the silicon bottom cell.

8. A method for preparing the solar cell according to any one of claims 1 to 7, characterized in that: include: sequentially preparing a first hole transport layer, a first perovskite layer and a first electron transport layer to obtain a narrow bandgap perovskite cell; On the side of the first electron transport layer facing the wide bandgap perovskite cell, a first composite layer is prepared, and an edge structure is prepared in the circumferential direction of the first composite layer, so that there is a gap between the inner wall of the edge structure and the outer wall of the first composite layer; A second hole transport layer, a second perovskite layer and a second electron transport layer are sequentially stacked on the side of the composite layer away from the narrow-bandgap perovskite cell to obtain a wide-bandgap perovskite cell and a solar cell.

9. The method according to claim 8, characterized in that The first perovskite layer is prepared by the following method: A perovskite with a band gap width of 1.3eV-1.60eV is dissolved in a solvent to form a first mixed solution. On one side of the first hole transport layer, the first mixed solution is spin-coated at a rotation speed of 1000rpm-2500rpm for 10s-35s, and then spin-coated at a rotation speed of 4000rpm-6000rpm for 20s-50s. Before the end of spin coating, chlorobenzene is added to the first mixed solution, and annealing is performed to obtain a first perovskite layer.

10. The method according to claim 8, characterized in that The second perovskite layer is prepared by the following method: A perovskite with a band gap width of 1.60eV-2.5eV is dissolved in a solvent to form a second mixed solution. On the side of the second hole transport layer away from the narrow band gap perovskite battery, the second mixed solution is spin-coated at a rotation speed of 600rpm-2000rpm for 10s-20s, and then spin-coated at a rotation speed of 3000rpm-6000rpm for 30s-50. Before the end of spin coating, anisole is added to the second mixed solution, and annealing is performed to obtain a first perovskite layer.

11. A photovoltaic module, characterized in that: The invention comprises at least one battery string, wherein the battery string comprises at least two solar cells according to any one of claims 1 to 7, or solar cells prepared by the method according to any one of claims 8 to 10.

12. A photovoltaic system, characterized in that: The photovoltaic module according to claim 11.

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