Solar cell and method of manufacturing the same, photovoltaic module, and photovoltaic system

Abstract

The application discloses a solar cell and a preparation method thereof, a photovoltaic module and a photovoltaic system, relates to the photovoltaic technical field, and the solar cell comprises a narrow-bandgap perovskite cell and a wide-bandgap perovskite cell which are sequentially stacked, the narrow-bandgap perovskite cell comprises a first hole transport layer, a first perovskite layer and a first electron transport layer which are sequentially stacked, the wide-bandgap perovskite cell comprises a second hole transport layer, a second perovskite layer and a second electron transport layer which are sequentially stacked in a direction away from the narrow-bandgap perovskite cell, and a first composite layer and an edge structure arranged in the circumferential direction of the first composite layer are arranged on the side of the first electron transport layer facing the wide-bandgap perovskite cell, 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 disclosed by the application has good cell performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular, to a solar cell and a preparation method thereof, a photovoltaic module and a photovoltaic system. BACKGROUND

[0002] With the development of photovoltaic technology, the efficiency of the current single-junction device gradually approaches the Shockley-Queisser efficiency limit. In order to break this limit, a perovskite-based tandem solar cell is an effective method. At present, the main research direction of the perovskite-based tandem solar cell is a perovskite / Si, perovskite / perovskite and perovskite / perovskite / Si double-junction solar cell and triple-junction device. However, when preparing the top perovskite film, the base has a step and the thickness of the wide-bandgap film is thin, so it is difficult to prepare a perovskite film with good coverage and no pores, thereby affecting the performance and stability of the device. SUMMARY

[0003] In a first aspect of the present application, a solar cell is provided, comprising a narrow-bandgap perovskite cell and a wide-bandgap perovskite cell stacked in sequence, the narrow-bandgap perovskite cell comprising a first hole transport layer, a first perovskite layer and a first electron transport layer stacked in sequence, the wide-bandgap perovskite cell comprising a second hole transport layer, a second perovskite layer and a second electron transport layer stacked in sequence away from the narrow-bandgap perovskite cell; a first recombination layer is arranged on the side of the first electron transport layer facing the wide-bandgap perovskite cell, and an edge structure is arranged circumferentially around the first recombination layer, and a gap exists between the inner wall of the edge structure and the outer wall of the first recombination layer.

[0004] Thus, by using the solar cell of the present application, the area of the first recombination 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, the circumferential edge structure arranged around the first recombination layer can reduce the probability of the solution containing perovskite before the first electron transport layer being spun on one side of the first electron transport layer and then leaving the first electron transport layer under the action of centrifugal force, thereby playing a blocking role and improving the residence time (liquid retention capacity) 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 recombination layer is 100-2000 μm.

[0006] In some embodiments, the cross section of the edge structure is arranged in axial symmetry.

[0007] In some embodiments, the edge structure comprises a plurality of spaced substructures, and the distance between each substructure is equal.

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

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

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

[0011] In some embodiments, the first perovskite layer has a band gap of 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 a1 is in the range of 0.9 - 1, b1 is in the range of 0.9 - 1, c1 is in the range of 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 PbI3, FA 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 )3.

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

[0014] In some embodiments, the second perovskite layer has a band gap of 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, where a2 is in the range of 0.5 - 0.9, b2 is in the range of 0.3 - 0.9; for example the second perovskite layer comprises FA0.7 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.

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

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

[0018] In some embodiments, the second recombination layer has a thickness of 15 nm to 30 nm.

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

[0020] In a second aspect of the present application, a method for preparing the solar cell of the first aspect is provided, comprising: sequentially preparing a first hole transport layer, a first perovskite layer and a first electron transport layer to obtain a narrow-bandgap perovskite cell; preparing a first composite layer on a side of the first electron transport layer facing the wide-bandgap perovskite cell, and preparing an edge structure on the periphery 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; sequentially preparing a second hole transport layer, a second perovskite layer and a second electron transport layer on a side of the composite layer away from the narrow-bandgap perovskite cell 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 dissolving a perovskite with a band gap width of 1.3 eV-1.60 eV in a solvent to form a first mixed solution, spin coating the first mixed solution at a speed of 1000 rpm-2500 rpm for 10 s-35 s on one side of the first hole transport layer, then spin coating at a speed of 4000 rpm-6000 rpm for 20 s-50 s, and adding chlorobenzene to the first mixed solution before the end of spin coating, and annealing to obtain the first perovskite layer.

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

[0023] In a third aspect of the present application, a photovoltaic module is provided, comprising at least one cell string, the cell string comprising at least two solar cells as described above.

[0024] In a fourth aspect of the present application, a photovoltaic system is provided, comprising the photovoltaic module as described above. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0027] Figure 2 FIG. 2 is a structural diagram of a solar cell according to another embodiment of the present application; Figure 1partial structural schematic diagram in the figure;

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

[0029] Figure 4 morphology diagram of the second perovskite layer prepared in the embodiment 1 and the comparative example 1 of the present application;

[0030] Figure 5 current density-voltage curve diagram of the solar cell prepared in the embodiment 1 and the comparative example 1 of the present application.

[0031] Explanation of Reference Signs:

[0032] 100, narrow band gap perovskite cell; 200, wide band gap 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 DESCRIPTION

[0033] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, but there will be cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters well known, repeated description of practically identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy, facilitating understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided so that those skilled in the art can 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 one of ordinary skill in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; unless otherwise stated, the values of the parameters mentioned in the present application can be measured by various measurement methods commonly used in the art (for example, can be tested according to the methods given in the embodiments of the present application).

[0035] The terms "comprise" and "have" and any variations thereof in the specification and claims of the present application are open-ended expressions, i.e. including the contents indicated by the present application, but not excluding other aspects.

[0036] In the description of the present application, the orientation or positional relationship indicated by the terms "width", "thickness" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0037] In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. "First feature", "second feature" can include one or more of the features.

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

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

[0040] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0041] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0042] With the development of photovoltaic technology, the efficiency of single-junction devices is gradually approaching the Shockley-Queisser efficiency limit. In order to break this limit, a perovskite-based tandem solar cell is an effective method. At present, the main research direction of perovskite-based tandem solar cells is perovskite / Si, perovskite / perovskite double-junction solar cells and perovskite / perovskite / Si triple-junction devices. However, the double-junction device or the triple-junction device is difficult to prepare a perovskite film with good coverage and no pores when preparing a top perovskite film due to the steps of the substrate and the thin thickness of the wide-bandgap film, thereby affecting the performance and stability of the device.

[0043] In the first aspect of the present application, the present application provides a solar cell, which refers to Figure 1The solar cell comprises a narrow-bandgap perovskite cell 100 and a wide-bandgap perovskite cell 200 stacked in sequence, the narrow-bandgap perovskite cell 100 comprises a first hole transport layer 06, a first perovskite layer 07 and a first electron transport layer 08 stacked in sequence, and the wide-bandgap perovskite cell 200 comprises a second hole transport layer 10, a second perovskite layer 11 and a second electron transport layer 12 stacked in sequence away from the narrow-bandgap perovskite cell 100; the first electron transport layer 08 is provided with a first composite layer 09 and an edge structure 14 arranged in the circumferential direction of the first composite layer 09 on one side facing the wide-bandgap perovskite cell 200, and 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 the present application, in the structure of the stacked cell, the area of the first composite layer 09 between the series structures is generally smaller than that of other charge transport layers or functional layers, which is mainly to avoid the lateral transmission of charges and reduce the occurrence of non-radiative recombination. The small-area composite layer will form a step in the device, which 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 three-junction device or a perovskite / perovskite two-junction device, due to the thin thickness of the perovskite layer (second perovskite layer 11) of the top cell, the step formed by the first composite layer 09 between the perovskite and the perovskite will seriously affect the film formation and crystallization of the top second perovskite layer 11. The present application designs the structure of the first composite layer 09 between the perovskite and the perovskite in the three-junction device or the two-junction device, and uses the edge structure 14, which 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 three-junction or two-junction device.

[0045] It can be understood that the perovskite / perovskite / silicon three-junction device refers to a cell with different bandgaps of perovskite materials in the top and middle layers, and a silicon-based absorption layer structure in the bottom layer. The perovskite / perovskite two-junction device is a series solar cell based on perovskite material, which is composed of two layers of perovskite materials with different bandgaps. Through reasonable design of the bandgap, higher 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 the spin coating method as an example, since the second hole transport layer 10 is relatively thin, after the first composite layer 09 and the second hole transport layer 10 are 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 the perovskite leaves the first electron transport layer 08 under the action of centrifugal force. The edge structure 14 plays a blocking role, improves the residence time (liquid retention capacity) of the perovskite solution on the first transport layer, and 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 arranged on the circumference of the composite layer and has a gap between the composite layer, which is within the protection scope of the present application.

[0048] As an example, Figure 2 The present application Figure 1 The 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 is shown in the figure, 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 further improve the performance and stability of the solar cell.

[0050] In some embodiments, the cross section of the edge structure 14 is arranged in axial symmetry, whereby the edge structure 14 is a regular morphology, on the one hand, facilitating the preparation of the above-mentioned edge structure 14 by using a mask plate, and on the other hand, after the solution containing perovskite before the perovskite is spin-coated to one side of the first electron transport layer 08, the blocking effect of the edge structure 14 is more uniform, which can further improve the film forming quality of the second perovskite layer 11, and further improve the performance and stability of the solar cell.

[0051] In some embodiments, the edge structure 14 comprises a plurality of spaced substructures, and the distance between each of the substructures is equal. In this way, the edge structure 14 is convenient to prepare by using a mask plate, and can save materials and have a better blocking effect.

[0052] In some embodiments, please refer toFigure 1 The solar cell is a three-junction device, further comprising a silicon bottom cell 300 arranged on the side of the narrow-bandgap perovskite cell 100 away from the wide-bandgap perovskite cell 200, the projected area of the first composite layer 09 on the silicon bottom cell 300 is S1, 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, 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 and the projected area of the other transport layer within the above range can further avoid lateral transport of charges, reduce the occurrence of non-radiative recombination, and further improve the performance of the solar cell.

[0053] In addition, the three-junction solar cell (the wide-bandgap perovskite cell 200 absorbs short-wave solar light, so that other waveband solar light transmits; the narrow-bandgap perovskite cell 100 absorbs solar light between the short-wave and long-wave bands and transmits long-wave solar light; and the silicon bottom cell 300 is used to absorb long-wave solar light) provided by the present application 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 10-20 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 lateral transport of charges, reduce the occurrence of non-radiative recombination, and at the same time have 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 lateral transport of charges, reduce the occurrence of non-radiative recombination, and at the same time have good light transmittance and carrier transport effect.

[0056] In some embodiments, the thickness of the edge structure 14 is 10-20 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 effectively improve the film forming quality of the top cell (wide-bandgap perovskite cell 200) and the performance of the three-junction or two-junction device.

[0057] In some embodiments, the material of the edge structure 14 includes a transparent conductive oxide, which includes at least one of indium tin oxide, fluorine-doped tin dioxide, and indium zinc oxide. The transparent conductive oxide can improve the film forming quality of the second perovskite layer 11, and has good light transmission 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. It can improve the utilization of light, and improve the photoelectric conversion efficiency of the perovskite battery and the efficiency of the solar cell.

[0059] In some embodiments, the band gap 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. Controlling the band gap of the first perovskite layer 07 within the above range, the band gap is narrower, which can greatly widen 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 a1 ranges from 0.9 to 1, b1 ranges from 0.9 to 1, and c1 ranges from 0.95 to 1. For 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 PbI3, FA 0.95 Cs 0.05 Pb(I 0.98 Br 0.02At least one of the following 3. The above-mentioned perovskites have a narrow band gap, which can significantly broaden the absorption spectrum range of solar cells and improve solar energy conversion efficiency.

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

[0062] In some embodiments, the band gap 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 band gap of the second perovskite layer 11 within the above range results in a wider band gap, which can significantly 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 a2 ranges from 0.5 to 0.9, and b2 ranges from 0.3 to 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 0.75 Cs 0.25 Pb(I 0.367 Br 0.633The perovskite has a wide band gap, which can greatly widen the absorption spectrum range of the solar cell and improve the solar energy conversion efficiency.

[0064] In some embodiments, referring to Figure 1 , the first electrode 13 is arranged on the side of the wide-band-gap perovskite solar cell 200 away from the narrow-band-gap perovskite solar cell 100, and the projected area of the first electrode 13 on the first electron transport layer 08 is greater than or equal to the projected area of the first recombination layer 09 on the first electron transport layer 08. In this way, the 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 three-junction device, and further comprises a silicon bottom cell 300 arranged on the side of the narrow-band-gap perovskite solar cell 100 away from the wide-band-gap perovskite solar cell 200. The second recombination layer 05 is arranged between the silicon bottom cell 300 and the narrow-band-gap perovskite solar cell 100. The second recombination layer 05 has good light transmission and carrier transport effects, and can avoid the lateral transport of charges and reduce the occurrence of non-radiative recombination, thereby improving the performance of the solar cell.

[0066] In some embodiments, the projected area of the second recombination layer 05 on the silicon bottom cell 300 is less than 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. In this way, the lateral transport of charges can be further avoided, the occurrence of non-radiative recombination can be reduced, and the performance of the solar cell can be improved.

[0067] In some embodiments, similar to the circumferential structure of the first recombination layer 09, the circumferential structure of the second recombination layer 05 can also be arranged with a gap from the first edge structure. When the first perovskite layer 07 is prepared, the film formation quality of the first perovskite layer 07 in the narrow-band-gap perovskite solar cell 100 can be effectively improved, and the film formation quality of the narrow-band-gap perovskite solar cell 100 and the performance of the three-junction or two-junction device can be effectively improved.

[0068] In some embodiments, the projected area of the second recombination layer 05 on the silicon bottom cell 300 is S3, 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, and S3 / S2=0.2-0.8, for example, 0.2, 0.5, 0.8, etc. By controlling the ratio of the projected area of the second recombination layer 05 on the silicon bottom cell 300 to the projected area of the other transport layers within the above range, the lateral transport of charges can be further avoided, the occurrence of non-radiative recombination can be reduced, and the performance of the solar cell can be improved.

[0069] In some embodiments, the second recombination layer 05 has a thickness of 15-30 nm; for example, it can be 15 nm, 20 nm, 30 nm, etc. Controlling the thickness of the second recombination layer 05 within the above range can further avoid lateral transmission of charges, reduce the occurrence of non-radiative recombination, while having good light transmittance and carrier transport effect.

[0070] In some embodiments, the second recombination layer 05 comprises a transparent conductive oxide, which comprises at least one of indium tin oxide, fluorine-doped tin dioxide, and indium zinc oxide. The above transparent conductive oxide can avoid lateral transmission of charges, reduce the occurrence of non-radiative recombination, while having good light transmittance and carrier transport effect.

[0071] In some embodiments, the silicon bottom cell 300 is provided with a second electrode 01 on the side 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 recombination layer 05 on the silicon bottom cell 300. In this way, lateral transmission of charges can be avoided, and the occurrence of non-radiative recombination can be reduced.

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

[0073] In some embodiments, the material of the first electron transport layer 08, the second electron transport layer 12, and the third electron transport layer 04 each independently comprises, but is not limited to, transparent oxides such as TiO2, SnO2, and ZnO, and the thickness of the first electron transport layer 08, the second electron transport layer 12, and the third electron transport layer 04 each independently is 20-50 nm, 10-30 nm, and 20-50 nm; the first hole transport layer 06, the second hole transport layer 10, and the third hole transport layer 02 each independently comprises, but is not limited to, organic small molecule materials (PTAA, HTM-1, HTM-2, etc.), inorganic materials (NiO, CuO, etc.), and the thickness of the first hole transport layer 06, the second hole transport layer 10, and the third hole transport layer 02 each independently is 1-15 nm, 1-25 nm, and 1-25 nm; the material of the bottom cell material layer 03 comprises, 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 material of the first electrode 13 and the second electrode 01 independently includes, but is not limited to, a transparent conductive oxide (ITO, FTO, IZO, etc.), a conductive polymer, and a metal electrode (Ag, Au, etc.), and the thickness of the first electrode 13 and the second electrode 01 is independently 20-40 nm, 200-500 nm.

[0075] In the second aspect of the present application, a preparation method of the solar cell of the first aspect is provided. The solar cell prepared by the method has a perovskite / perovskite / silicon triple-junction device or a perovskite / perovskite double-junction device. Since the thickness of the perovskite layer (the second perovskite layer 11) of the top cell is thin, the step formed by the first composite layer 09 between the perovskite and the perovskite seriously affects the film formation and crystallization of the top second perovskite layer 11. The present application designs the structure of the first composite layer 09 between the perovskite and the perovskite in the triple-junction device or the double-junction device, and uses the edge structure 14, which can effectively improve the film formation quality of the second perovskite layer 11 in the wide-bandgap perovskite cell 200, and 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.

[0076] Referring to Figure 3 The preparation method of the solar cell 100 of the embodiments of the present application includes:

[0077] S100: sequentially preparing 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 comprising a silicon bottom cell 300 arranged on the side of the narrow-bandgap perovskite cell 100 away from the wide-bandgap perovskite cell 200, and the silicon bottom cell 300 comprises a third electron transport layer 04, a bottom cell material layer 03, and a third hole transport layer 02 sequentially arranged in the direction away from the narrow-bandgap perovskite cell 100. The preparation method of each layer is as follows:

[0079] An n-type c-Si wafer with a bulk resistivity of 1.5 ± 0.5 Ωcm is used as a 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 surface of the wafer, and finally loaded into a plasma enhanced chemical vapor deposition (PECVD). During the PECVD process, (i) a-Si:H / (n) μc-SiOx:H electron transport layer (third electron transport layer 04) is deposited on the front side, and (i) a-Si:H / (p) μc-Si:H hole transport layer (third hole transport layer 02) is deposited on the other side. Subsequently, a 10-20 nm and 15-50 nm thick ITO conductive layer is deposited on the front and back sides of the silicon wafer, respectively, using a radio frequency magnetron sputtering technique. Finally, a layer of silver paste screen is printed on the back of the wafer, and the resulting cell is placed in an oven at 150-180°C for curing.

[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 band gap 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 the 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 the spin coating can partially miscible with the precursor solvent, quickly "extract" the residual solvent, shorten the solvent evaporation time, and force the perovskite to quickly nucleate and crystallize.

[0084] In some embodiments, the concentration of the perovskite in the first mixed solution 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 the perovskite in the first mixed solution within the above range can effectively regulate the current distribution of the triple-junction device, while avoiding the introduction of a large number of defects, and preparing a first perovskite layer 07 with good quality.

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

[0086] S200: A first composite layer 09 is prepared on the side of the first electron transport layer 08 facing the wide-bandgap perovskite battery 200, and an edge structure 14 is prepared on the circumference 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, by evaporation.

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

[0089] S300: A second hole transport layer 10, a second perovskite layer 11, and a second electron transport layer 12 are sequentially prepared on the side of the composite layer away from the narrow-bandgap perovskite battery 100, to obtain a wide-bandgap perovskite battery 200, thereby 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 a conventional method 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: A perovskite with a bandgap width of 1.60 eV-2.5 eV is dissolved in a solvent to form a second mixed solution, the second mixed solution is spin coated on the side of the second hole transport layer 10 away from the narrow-bandgap perovskite battery 100, and before the spin coating is completed, anisole is added to the second mixed solution, and annealing is performed to obtain a first perovskite layer 07.

[0093] In some embodiments, the concentration of perovskite in the second mixed solution 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 uniformly at a low rotation speed and control the thickness of the thin film at a high rotation speed, thereby preparing a second perovskite layer 11 with good quality.

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

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

[0096] In summary, the preparation method of the above-mentioned solar cell and the prepared solar cell, in a perovskite / perovskite / silicon triple-junction device or a perovskite / perovskite double-junction device, since the thickness of the perovskite layer (second perovskite layer 11) of the top cell is relatively thin, the step formed by the first composite layer 09 between the perovskite and the perovskite will seriously affect the film formation and crystallization of the top second perovskite layer 11. The present application designs the structure of the first composite layer 09 between the perovskite and the perovskite in the triple-junction device or the double-junction device, uses the edge structure 14, which 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.

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

[0098] In some embodiments, the solar cells can be connected together by series welding, so as to collect the electrical energy generated by the individual solar cells for subsequent transmission.

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

[0100] For example, the photovoltaic module further comprises an encapsulation layer and a cover plate, the encapsulation layer is used to cover the surface of the cell string, and the cover plate is used to cover the surface of the encapsulation layer away from the cell string.

[0101] In the fourth aspect of the present application, a photovoltaic system is provided, which comprises the photovoltaic module as described above.

[0102] The photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., or a device or apparatus using solar energy to generate electricity, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. It can be understood that the application scenarios of the photovoltaic system are not limited to the above, that is, the photovoltaic system can be applied in all fields requiring solar energy to generate electricity. For example, the photovoltaic system can comprise a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of a plurality of photovoltaic modules, for example, a plurality of photovoltaic modules can form a plurality of photovoltaic arrays, the photovoltaic array is connected to the combiner box, the combiner box can combine the current generated by the photovoltaic array, the combined current flows through the inverter to convert into alternating current required by the power grid, and then is connected to the power grid to realize solar power supply.

[0103] The scheme of the present application is described below by means of specific examples. It should be noted that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. If the specific technology or condition is not specified in the examples, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0104] Example 1

[0105] Silicon bottom cell preparation: n-type c-Si wafers with bulk resistivity of 1.5±0.5 Ωcm were used as substrates. The wafers were first processed in dilute KOH solution, then subjected to standard RCA cleaning, followed by dilute hydrofluoric acid (HF) etching to remove the oxide layer formed on the surface of the wafer, and finally loaded into a plasma-enhanced chemical vapor deposition (PECVD). During the PECVD process, (i) a-Si:H / (n) μc-SiOx:H electron transport layer (third electron transport layer 04) was deposited on the front side, and (i) a-Si:H / (p) μc-Si:H hole transport layer (third hole transport layer 02) was deposited on the other side. Subsequently, 10-20 nm and 15-50 nm thick ITO conductive layers were deposited on the front and back sides of the silicon wafer, respectively, using radio frequency magnetron sputtering technology. Finally, a layer of silver paste screen was printed on the back side of the wafer, and the resulting cell was placed in an oven at 150-180°C for curing, obtaining a silicon bottom cell.

[0106] 1. The silicon bottom cell was irradiated under UV light for 15 minutes, then a SAM solution (MEo-2PACz:2PACz was 3:1, total concentration was 0.5 mg / mL) was spin-coated at 4000 rpm for 30 seconds, and then annealed at 100°C for 10 minutes to obtain a SAM layer with a thickness of 2 nm, obtaining a first hole transport layer with a thickness of 2 nm.

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

[0108] 3. The first electron transport layer (C 60 layer with a thickness of 15 nm, SnO2 layer with a thickness of 30 nm) and IZO (composite layer) with a thickness of 20 nm were sequentially evaporated onto the above device, and after the IZO evaporation was completed, a 20 nm layer was plated on the edge of the composite IZO layer using a mask, as shown in the edge structure ITO in the edge structure shown in 1. Figure 1 and Figure 2

[0109] 4. Then 15 nm of NiO x ​A SAM solution (MEo-2PACz:2PACz is 3:1, total concentration is 0.5 mg / mL) is spin-coated at 4000 rpm for 30 seconds, and then annealed at 100°C for 10 minutes to obtain a SAM layer with a thickness of 2 nm, and then a NiO x layer with a thickness of 12 nm is deposited by electron beam evaporation to form a second hole transport layer, and the total thickness of the SAM layer and the second hole transport layer is 17 nm.

[0110] 5. A broadband perovskite (FA 0.7 Cs 0.3 Pb(I 0.333 Br 0.667 )3) is dissolved 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 and then 4000 rpm for 40 s, and 160 microliters of anisole are added dropwise in the last 10 s, and then annealed at 100°C for 20 minutes to obtain a second perovskite layer with a thickness of 400 nm.

[0111] 7. A second electron transport layer (a C 60 layer with a thickness of 15 nm), a first electrode (IZO 30 nm, Ag 400 nm), and an anti-reflective film (MgF2 110 nm) are sequentially deposited on 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 of the ITO is the edge structure ITO shown in FIG. 2. Figure 2

[0114] Example 3

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

[0116] Comparative Example 1

[0117] The preparation process is basically the same as that of Example 1, except that no edge structure is prepared.

[0118] The morphology of the second perovskite layer prepared in Example 1 and Comparative Example 1 is shown in FIG. 4. From the film morphology, it can be found that after introducing the edge structure to the periphery of the composite layer, the quality of the broadband perovskite film (the second perovskite layer) is greatly improved, and it can be found that in Comparative Example 1, a clear boundary is formed at the step of the composite layer, which will cause uneven stress distribution in the second perovskite layer, seriously affecting the film quality, and ultimately greatly affecting the device performance. Figure 4

[0119] ​​​The open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, and energy conversion efficiency Eff of the solar cell were tested according to the IEC 61730 standard, and the test results are shown in Table 1 and Figure 5 .

[0120] Figure 5 The current density-voltage curve of the perovskite cell prepared in Example 1 and Comparative Example 1 is shown in FIG. 1, and it can be seen that the solar cell of the present application has significantly better performance in all aspects than Comparative Example 1. Figure 3

[0121] Table 1

[0122]

[0123] As can be seen from Table 1, in the solar cells of Examples 1-3 of the present application, by structurally designing the composite layer between the perovskite and the perovskite in the triple-junction device and using an edge structure, the film formation quality of the second perovskite layer in the wide-bandgap perovskite cell can be effectively improved, the film formation quality of the top cell (wide-bandgap perovskite cell) and the performance of the triple-junction device can be effectively improved. Comparative Example 1 does not use an edge structure, and 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-described embodiments. The above-described embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the components of the embodiments are also included in the scope of the present application.​

Claims

1. A solar cell, characterized in that, The invention includes a narrow bandgap perovskite cell and a wide bandgap perovskite cell stacked sequentially. The narrow bandgap perovskite cell includes a first hole transport layer, a first perovskite layer and a first electron transport layer stacked sequentially. The wide bandgap perovskite cell includes a second hole transport layer, a second perovskite layer and a second electron transport layer stacked sequentially along a direction away from the narrow bandgap perovskite cell. The first electron transport layer has a first composite layer and an edge structure disposed around the first composite layer on the side facing the wide-bandgap perovskite solar cell. There is a gap between the inner wall of the edge structure and the 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 100μm-2000μm; and / or, The cross-section of the edge structure is arranged in an axisymmetric manner; and / or, The edge structure includes multiple spaced substructures, with equal distances between each substructure.

3. The solar cell according to claim 1 or 2, characterized in that, The thickness of the first perovskite layer is 600 nm-1200 nm; 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 300 nm-500 nm; 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 includes (FA) a1 MA (1-a1) ) b1 Cs (1-b1) Pb(I c1 Br (1-c1) )3, where a1 ranges from 0.9 to 1, b1 ranges from 0.9 to 1, and c1 ranges from 0.95 to 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 to 0.9 and b2 ranges from 0.3 to 0.

9.

5. The solar cell according to claim 1 or 2, characterized in that, The wide-bandgap perovskite solar cell has a first electrode on the side opposite to the narrow-bandgap perovskite solar cell, and the projected area of ​​the first electrode on the first electron transport layer is greater than or equal to the 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 also includes a silicon base cell disposed on the side of the narrow bandgap perovskite cell away from the wide bandgap perovskite cell. A second composite layer is provided between the silicon base 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, The silicon substrate cell has a second electrode on the side opposite to the narrow bandgap perovskite cell, and the projected area of ​​the second electrode on the silicon substrate cell is greater than or equal to the projected area of ​​the second composite layer on the silicon substrate cell.

8. A method for preparing a solar cell according to any one of claims 1-7, characterized in that, include: A narrow bandgap perovskite solar cell was obtained by sequentially fabricating a first hole transport layer, a first perovskite layer, and a first electron transport layer. On the side of the first electron transport layer facing the wide-bandgap perovskite solar 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 opposite to the narrow bandgap perovskite solar cell to obtain a wide bandgap perovskite solar cell, thus obtaining a solar cell.

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

10. The method according to claim 8, characterized in that, The second perovskite layer was prepared using the following method: A second mixed solution is formed by dissolving perovskite with a bandgap width of 1.60 eV-2.5 eV in a solvent. On the side of the second hole transport layer opposite to the narrow bandgap perovskite solar cell, the second mixed solution is spin-coated at 600 rpm-2000 rpm for 10 s-20 s, and then spin-coated at 3000 rpm-6000 rpm for 30 s-50 s. Before the spin-coating is completed, anisole is added to the second mixed solution, and the mixture is annealed to obtain the first perovskite layer.

11. A photovoltaic module, characterized in that, It includes at least one battery string, the battery string comprising at least two solar cells according to any one of claims 1-7, or solar cells prepared using the method according to any one of claims 8-10.

12. A photovoltaic system, characterized in that, Includes the photovoltaic module as described in claim 11.

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