CN218351478U

CN218351478U - Solar cell and photovoltaic module

Info

Publication number: CN218351478U
Application number: CN202222291255.0U
Authority: CN
Inventors: 徐孟雷; 李白茹; 杨洁; 张昕宇
Original assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Current assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Priority date: 2022-08-29
Filing date: 2022-08-29
Publication date: 2023-01-20
Anticipated expiration: 2032-08-29

Abstract

The application relates to a solar cell and a photovoltaic module, comprising a bottom cell, a first electrode, a second electrode and a third electrode, wherein the bottom cell comprises a front surface and a back surface which are opposite; the perovskite top battery comprises a hole transmission layer, a perovskite layer, an electron transmission layer and a conductive composite layer which are arranged on the surface of the composite layer in a stacking mode, the conductive composite layer comprises at least one group of first conductive layers and second conductive layers which are arranged in a stacking mode, the second conductive layers are arranged between the first conductive layers and the electron transmission layer, the first conductive layers comprise first transparent conductive film layers, and the second conductive layers comprise metal conductive film layers corresponding to metalized areas and second transparent conductive film layers corresponding to non-metalized areas; a back electrode located on the back side of the bottom cell. The existence of metal conductive film layer in this application conductive composite layer can improve conductive composite layer's electric conductive property for solar cell need not set up positive electrode, can obtain higher electric conductive property, thereby improves the conversion efficiency of battery.

Description

Solar cell and photovoltaic module

Technical Field

The present application relates to the field of photovoltaic cell technology, and in particular, to a solar cell and a photovoltaic module.

Background

With the increasing energy crisis and environmental pollution, the demand of human beings for renewable energy sources is increasing. Solar energy has the advantages of safety, no pollution, no geographical condition limitation and the like, and is one of various renewable energy sources which is most widely applied and has the greatest development prospect. Among various technologies for effectively utilizing solar energy, photovoltaic power generation is undoubtedly one of the most promising directions. Among a plurality of novel solar cells, the perovskite solar cell has the advantages of high efficiency, solution-soluble preparation, low cost and the like, the solar conversion efficiency of the perovskite solar cell is close to that of a silicon-based solar cell, and with the deep research on the silicon-based solar cell, the cell efficiency of the perovskite solar cell is close to the theoretical maximum efficiency, so that the improvement of the photoelectric conversion efficiency of the perovskite solar cell becomes the key of the development in the field.

The laminated cell technology is one of the most effective ways for improving the photoelectric conversion efficiency of the solar cell, and since the perovskite material has very strong absorption in a visible light region of 350-700 nm, and silicon absorbs near infrared light of 700-1100 nm, the silicon/perovskite laminated structure solar cell composed of perovskite and silicon is increasingly researched, and the efficiency is higher than that of a monocrystalline silicon cell or a perovskite cell. However, the existing silicon/perovskite solar cell with a laminated structure has poor conductivity, so that the improvement of the conversion efficiency of the cell is limited to a certain extent.

Therefore, there is an urgent need to further improve the conductivity of the silicon/perovskite solar cell with a stacked structure to improve the photoelectric conversion efficiency of the cell.

SUMMERY OF THE UTILITY MODEL

In view of this, the present application provides a solar cell and a photovoltaic module, in which the solar cell has excellent conductivity, and the conversion efficiency of the solar cell can be improved while the manufacturing cost can be reduced.

In a first aspect, the present application provides a solar cell comprising:

a bottom cell comprising opposing front and back sides;

the perovskite top battery comprises a hole transmission layer, a perovskite layer, an electron transmission layer and a conductive composite layer which are arranged on the surface of the composite layer in a stacked mode, the conductive composite layer comprises at least one group of first conductive layer and at least one group of second conductive layer which are arranged in a stacked mode, the second conductive layer is arranged between the first conductive layer and the electron transmission layer, the first conductive layer comprises a first transparent conductive film layer, and the second conductive layer comprises a metal conductive film layer corresponding to a metalized area and a second transparent conductive film layer corresponding to a non-metalized area;

a back electrode located on the back side of the bottom cell.

In one possible embodiment, the material of the metal conductive film layer is any one of Ni, cu, al, ni, sn, zn, ag, and Au.

In one possible embodiment, the thickness of the metal conductive film layer is 0.1nm to 10nm.

In one possible embodiment, the conductive composite layer has a thickness of 20nm to 200nm.

In one possible embodiment, the conductive composite layer further includes a third conductive layer between the second conductive layer and the electron transport layer, the third conductive layer including a third transparent conductive film layer.

In one possible embodiment, the thickness of the second conductive layer is greater than the thickness of the first conductive layer.

In one possible embodiment, the solar cell further includes a front electrode on the surface of the first conductive layer located at the outermost layer.

In a possible implementation mode, the transverse grid line spacing of the front electrode is 1 mm-4 mm; and/or the longitudinal grid line spacing of the front electrode is 1-4 mm.

In one possible embodiment, the ratio of the height of the front electrode to the height of the rear electrode is greater than or equal to 0.1.

In a second aspect, the present application provides a photovoltaic module comprising a plurality of strings of solar cells, each string of solar cells being formed by electrically connecting solar cells of the first aspect.

The technical scheme of the application has at least the following beneficial effects:

the utility model provides a solar cell, its conductive property that can improve the conductive composite layer through setting up the metal conductive film layer that corresponds to metallization region in the conductive composite layer to make solar cell need not set up positive electrode, can obtain higher conductive property, improve laminate cell charge collection efficiency, thereby improve the conversion efficiency of battery. In addition, the second conducting layer is located between first conducting layer and the electron transport layer in this application, and first conducting layer is in the outmost of battery promptly, can play the effect of the electrically conductive rete of protection metal, avoids the electrically conductive rete of metal to receive external influence.

Drawings

In order to clearly illustrate the embodiments or technical solutions of the present application, the drawings used in the embodiments or technical solutions of the present application will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic structural diagram of a solar cell according to the present application;

FIG. 2 is a schematic diagram of a solar cell with a second conductive layer of the four-layer structure of the present application;

FIG. 3 is a flow chart of the solar cell fabrication process of the present application;

FIG. 4 is a schematic diagram of a bottom cell of the present application;

FIG. 5 is a schematic structural view of a bottom cell and a composite layer of the present application;

FIG. 6 is a schematic structural view of a hole transport layer, a perovskite layer and an electron transport layer formed on the surface of a composite layer according to the present application;

FIG. 7 is a schematic structural diagram of a second conductive layer formed on the surface of the electron transport layer according to the present application;

FIG. 8 is a schematic structural diagram of a composite conductive layer of the present application including a second conductive layer and a third transparent conductive layer;

FIG. 9 is a schematic structural diagram of a composite conductive layer of the present application including a first conductive layer, a second conductive layer, and a third transparent conductive layer;

fig. 10 is a schematic structural view illustrating a front electrode formed on a surface of an outermost first conductive layer according to the present application;

FIG. 11 is a schematic structural diagram of a solar cell including a front electrode according to the present application;

fig. 12 is a schematic structural view of a photovoltaic module according to the present application.

In the figure: 1-bottom cell;

2-a composite layer;

3-perovskite top cells;

31-a hole transport layer;

32-perovskite layer;

33-electron transport layer;

34-a conductive composite layer;

341-first conductive layer;

342-a second conductive layer;

3421-a metal conductive film layer;

3422-a second transparent conductive film layer;

343-a third conductive layer;

4-a back electrode;

5-a front electrode;

1000-a photovoltaic module;

100-solar cell;

200-a first cover plate;

300-a first encapsulating adhesive layer;

400-a second packaging glue layer;

500-second cover plate.

Detailed Description

For better understanding of the technical solutions of the present application, the following detailed descriptions of the embodiments of the present application are provided with reference to the accompanying drawings.

It should be understood that the embodiments described are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be understood that the term "and/or" as used herein is merely a relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter associated objects are in an "or" relationship.

In the conventional silicon/perovskite laminated structure solar cell, the transparent conductive layer is mostly a thin film made of materials such as ITO, IZO and TCO, and the conductivity is poor, and in order to improve the conductivity of the cell, an electrode made of metal needs to be deposited on the surface of the transparent conductive layer to improve the conductivity, however, the price of the electrode (usually gold, silver, etc.) is expensive, so that the cost of the solar cell is increased.

Therefore, the present application provides a solar cell 100, in which the conductivity of the solar cell 100 is high and the cost is low.

As shown in fig. 1, the solar cell 100 of the present application is a schematic structural diagram of the solar cell 100 of the present application, and includes:

a bottom cell 1, the bottom cell 1 comprising opposing front and back sides;

the composite layer 2 and the perovskite top battery 3 are positioned on the front surface of the bottom battery 1, the perovskite top battery 3 comprises a hole transport layer 31, a perovskite layer 32, an electron transport layer 33 and a conductive composite layer 34 which are arranged on the surface of the composite layer 2 in a laminated mode, the conductive composite layer 34 comprises at least one group of first conductive layer 341 and second conductive layer 342 which are arranged in a laminated mode, the second conductive layer 342 is positioned between the first conductive layer 341 and the electron transport layer 33, the first conductive layer 341 comprises a first transparent conductive film layer, and the second conductive layer 342 comprises a metal conductive film layer 3421 corresponding to a metalized area and a second transparent conductive film layer 3422 corresponding to a non-metalized area;

a back electrode 4 located on the back side of the bottom cell 1.

In the above scheme, the conductive layer 3421 corresponding to the metalized region is disposed in the conductive composite layer 34, so that the conductive performance of the conductive composite layer 34 can be improved, the solar cell 100 does not need to have the front electrode 5, and a high conductive performance can be obtained, thereby improving the charge collection efficiency of the tandem cell and improving the conversion efficiency of the cell. In addition, in this application, the second conductive layer 342 is located between the first conductive layer 341 and the electron transport layer 33, that is, the first conductive layer 341 is located at the outermost layer of the battery, which can protect the metal conductive film layer 3421 and prevent the metal conductive film layer 3421 from being affected by the outside.

This application pertinence sets up the electrically conductive rete of metal 3421 in the metallization region of electrically conductive composite bed, compares with the metal level that sets up the whole layer, does not influence the absorption of battery to the sunlight when this application can improve the electric conductivity of electrically conductive composite bed, and then makes the photoelectric conversion efficiency of battery have higher promotion.

It is to be understood that since the solar cell 100 of the present application does not include the front electrode 5, the metalized region of the present application refers to a region of the second conductive layer 342 corresponding to the back electrode 4, and the non-metalized region refers to a region of the second conductive layer 342 other than the metalized region.

The present application does not limit the type of the bottom cell 1, and the bottom cell 1 may be, for example, a heterojunction cell (HIJ cell), a PERC cell, a PERT cell, a TOPCon cell, or the like.

Illustratively, when the base cell 1 is a heterojunction cell, the heterojunction cell includes a crystalline silicon substrate having opposite front and back surfaces, the front surface of the semiconductor substrate is sequentially provided with an intrinsic type hydrogenated amorphous silicon layer, a P type hydrogenated amorphous silicon layer, and a front transparent conductive layer, the composite layer is located on the surface of the transparent conductive layer, the back surface of the crystalline silicon substrate is sequentially provided with an intrinsic type hydrogenated amorphous silicon layer, an n type hydrogenated amorphous silicon layer, and a back transparent conductive layer, the back electrode 4 is located on the surface of the transparent conductive layer, the front surface of the semiconductor substrate refers to the surface facing sunlight, and the back surface of the semiconductor substrate refers to the surface facing away from sunlight.

Illustratively, when the bottom cell 1 is a PERT cell, the PERT cell includes a first passivation layer, a second passivation layer, an n-type silicon wafer, a P-type doped emitter, a tunneling layer, and a doped polysilicon layer, which are sequentially disposed from bottom to top, wherein a gate line of the back electrode 4 is embedded into the bottoms of the first passivation layer and the second passivation layer to contact with the n-type silicon wafer, and the P-type doped emitter, the tunneling layer, and the doped polysilicon layer form a tunneling junction. Wherein: the first passivation layer includes a silicon nitride layer, a silicon oxide layer, or a stacked structure of silicon nitride and silicon oxide. The second passivation layer includes a phosphorus diffusion layer. The tunneling layer includes at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon carbide layer. The doped polycrystalline silicon layer is at least one of polycrystalline or nanocrystalline silicon oxide, silicon nitride or silicon carbide processed at high temperature.

Illustratively, when the bottom cell is a TOPCon cell, the TOPCon cell includes a front passivation layer, an n-type silicon wafer, a tunneling layer and a doped polysilicon layer, which are sequentially disposed from bottom to top, the back electrode 4 is embedded in the bottom surface of the front passivation layer and contacts with the n-type silicon wafer, the doped polysilicon layer contacts with the composite layer, and the front passivation layer includes a silicon nitride layer, a silicon oxide layer or a stacked structure of silicon nitride and silicon oxide. The tunneling layer includes at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon carbide layer. The doped polycrystalline silicon layer is at least one of polycrystalline or nanocrystalline silicon oxide, silicon nitride or silicon carbide processed at high temperature. The tunneling layer and the doped polysilicon layer jointly form a passivation contact structure.

In the present application, the composite layer 2 includes a tunnel junction or a transparent conductive substance, the tunnel junction can combine the photo-generated electrons generated by the perovskite top cell 3 and the photo-generated holes generated by the bottom cell 1 in the tunnel junction, and for example, the transparent conductive substance may be TCOs, IZO (indium-doped zinc oxide), ITO, a transparent electrode Ag, and the like, which have good photon permeability and conductivity, and can connect the bottom cell 1 and the perovskite top cell 3 to realize ohmic contact, thereby ensuring the combination of electrons and holes inside the cell, and thereby improving the band gap matching between the bottom cell 1 and the top cell.

In some embodiments, the metal conductive film layer 3421 is made of any one of Ni, cu, al, ni, sn, zn, ag and Au, and the conductivity of the metal conductive film layer 3421 made of the above materials is greater than that of the transparent conductive film layer (generally, ITO, IZO, TCO film, etc.), which can improve the lateral transmission of electrons in the conductive composite layer 34, so as to improve the conductivity of the conductive composite layer 34, thereby reducing the series resistance of the battery, improving the charge transmission capability, improving the short circuit density of the solar cell 100, and improving the fill factor, thereby effectively improving the photoelectric conversion efficiency of the solar cell 100. Preferably, the material of the metal conductive film layer 3421 includes at least one of Ni, cu, al, sn, and Zn having unstable properties, which is relatively low in cost, and since the surface of the metal conductive film layer 3421 is covered with the first transparent conductive film layer, ni, cu, al, sn, and Zn having unstable properties can still exhibit high conductive performance.

In some embodiments, at least one of the first conductive layer 341 and the second conductive layer 342 stacked on the conductive composite layer 34 is provided, that is, the two-layer structure of the first conductive layer 341 and the second conductive layer 342 in this application is a composite layer structure of one group, two groups, three groups, four groups, and the like, and the number of the groups of the first conductive layer 341 and the second conductive layer 342 in this application is not limited, and can be customized according to the conductive performance requirement of the solar cell 100. As shown in fig. 1, the solar cell 100 is a two-layer structure, one of which is a first transparent conductive layer, and the other is a second conductive layer 342, wherein the first transparent conductive layer is located at the outermost layer of the solar cell 100. As shown in fig. 2, in the solar cell 100 having two sets of four-layer structure, when the number of the conductive composite layers 34 in the solar cell 100 is greater than or equal to 2 sets, the materials of the metal conductive film layers 3421 in different sets may be the same or different. In some embodiments, when the materials of the different groups of metal conductive film layers 3421 are different, the instability of the metal conductive film layer 3421 far away from the electron transport layer 33 is smaller than the instability of the metal conductive film layer 3421 near the electron transport layer 33, thereby improving the electrical performance of the battery.

In some embodiments, the thickness of the metal conductive film layer 3421 is 0.1nm to 10nm, specifically, the thickness of the metal conductive film layer 3421 is 0.1nm, 0.5nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, and the like, and in some embodiments, the thickness of the metal conductive film layer 3421 is the thickness of the second conductive layer 342.

In some embodiments, the thickness of the conductive composite layer 34 is 20nm to 200nm, and in particular, the thickness of the conductive composite layer 34 may be 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 100nm, 120nm, 150nm, 180nm, and 200nm. Compared with the thickness of the transparent conducting layer of the conventional silicon/perovskite laminated cell, the thickness of the conducting composite layer 34 is equivalent, namely the conducting performance of the cell can be improved on the premise of not changing the thickness of the conducting layer. Preferably, the thickness of the conductive composite layer 34 is 50nm to 150nm.

In some embodiments, the conductive composite layer 34 further includes a third conductive layer 343, the third conductive layer 343 is located between the second conductive layer 342 and the electron transport layer 33, and the third conductive layer 343 includes a third transparent conductive film layer, i.e., in the conductive composite layer 34 of the solar cell 100 of the present application, both surfaces of the second conductive layer 342 are provided with transparent conductive layers.

In some embodiments, the thickness of the second conductive layer 342 is greater than that of the first conductive layer 341, and the second conductive layer 342 includes the metal conductive film layer 3421, so that the conductivity of the conductive composite layer 34 can be further improved and the carrier collection efficiency can be improved by defining the thickness of the second conductive layer 342 to be greater than that of the first conductive layer 341.

It is understood that when the solar cell 100 includes the front electrode 5, the metal conductive film layer 3421 may correspond to the position of the front electrode 5 and also correspond to the position of the back electrode 4; preferably, in order to enable the solar cell 100 to absorb more sunlight, the metal conductive film layer 3421 may correspond to the position of the front electrode 5.

In some embodiments, the solar cell 100 further includes a front electrode 5 on the surface of the outermost first conductive layer 341. The conductivity of the solar cell 100 can be further improved by the synergistic effect of the metal conductive film layer 3421 of the metalized region and the front electrode 5.

In some embodiments, the material of the front electrode 5 is any one of Ag and Au.

In some embodiments, the material of the back electrode 4 is any one of Ag and Au.

In some embodiments, when the solar cell 100 of the present application includes the front electrode 5, the present application may reduce the usage amount of the front electrode 5 by providing the conductive composite layer 34, and specifically, may reduce the manufacturing cost while ensuring the conductivity of the cell by increasing (enlarging) the pitch of the grid lines of the front electrode 5.

The transverse grid line spacing of the front electrode 5 is 1 mm-4 mm, specifically, the transverse grid line spacing of the front electrode 5 is 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm and 4mm, and the transverse grid line spacing of the conventional silicon/perovskite battery is generally 0.5 mm-2 mm. The longitudinal grid line spacing of the front electrode 5 is 1 mm-4 mm, specifically, the longitudinal grid line spacing of the front electrode 5 is 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm and 4mm. The distance between the grid lines of the front electrode 5 is larger than the conventional electrode grid line distance, so that the using amount of the electrode can be saved, and the conductivity of the battery is not influenced while the cost is saved.

In some embodiments, the ratio of the height of the front electrode 5 to the height of the back electrode 4 is greater than or equal to 0.1, specifically, the ratio of the height of the front electrode 5 to the height of the back electrode 4 may be 0.1, 0.15, 0.20, 0.25, 0.30, 0.50 and 0.70, and it is understood that the height of the back electrode 4 of the present application is the same as the height of the back electrode 4 and the front electrode 5 in a conventional silicon/perovskite stacked cell. The present application can reduce the usage amount of the front electrode 5 by providing the conductive composite layer 34, specifically, can reduce the height of the front electrode 5, thereby ensuring the conductivity of the battery and reducing the manufacturing cost, preferably, the ratio of the height of the front electrode 5 to the height of the back electrode 4 is 0.10 to 0.30.

The present application further provides a method for manufacturing the solar cell 100, as shown in fig. 3, including the following steps:

providing a bottom cell 1, the bottom cell 1 comprising opposing front and back sides;

forming a composite layer 2 and a perovskite top cell 3 on the front surface of a bottom cell 1, wherein the perovskite top cell 3 comprises a hole transport layer 31, a perovskite layer 32, an electron transport layer 33 and a conductive composite layer 34 which are arranged on the surface of the composite layer 2 in a stacking mode, the conductive composite layer 34 comprises at least one set of a first conductive layer 341 and a second conductive layer 342 which are arranged in a stacking mode, the second conductive layer 342 is located between the first conductive layer 341 and the electron transport layer 33, the first conductive layer 341 comprises a first transparent conductive film layer, and the second conductive layer 342 comprises a metal conductive film layer 3421 corresponding to a metalized area and a second transparent conductive film layer 3422 corresponding to a non-metalized area;

a back electrode 4 is formed on the back surface of the bottom cell 1.

In the above solution, the conductive composite layer 34 is formed on the surface of the electron transport layer 33, the conductive composite layer 34 includes the first conductive layer 341 and the second conductive layer 342 that are stacked, where the second conductive layer 342 includes the metal conductive film layer 3421 corresponding to the metalized region and the second transparent conductive film layer 3422 corresponding to the non-metalized region, and due to the existence of the metal conductive film layer 3421, the conductivity of the conductive composite layer 34 can be improved, so that the solar cell 100 can obtain higher conductivity without the front electrode 5, thereby improving the charge collection efficiency of the stacked cell, and finally improving the conversion efficiency of the cell. In addition, in this application, the second conductive layer 342 is located between the first conductive layer 341 and the electron transport layer 33, that is, the first conductive layer 341 is located at the outermost layer of the battery, which can protect the metal conductive film layer 3421 and prevent the metal conductive film layer 3421 from being affected by the outside.

This application pertinence sets up the electrically conductive rete of metal 3421 in the metallization region of electrically conductive composite bed, compares with the metal level that sets up whole layer, does not influence the absorption of battery to the sunlight when this application can improve the electric conductivity of electrically conductive composite bed, and then makes the photoelectric conversion efficiency of battery have higher promotion.

It is to be understood that the solar cell 100 of the present application is a stacked cell of a silicon cell and a perovskite solar cell 100, and any modification, equivalent replacement, improvement, etc. made by those skilled in the art without departing from the concept of the present application shall be included in the protection scope of the present application.

The production method of the present application is described below according to specific examples.

Step S100, providing a bottom cell 1, wherein the bottom cell 1 includes opposite front and back surfaces, and the structure of the bottom cell 1 is shown in fig. 4.

In some embodiments, the base cell 1 of the present application includes forming the base cell 1 on a surface of a semiconductor substrate. The present application does not limit the type and the preparation method of the bottom cell 1, and the bottom cell 1 may be, for example, a heterojunction cell (HIJ cell), a P-type cell (PERT cell), a TOPCon cell, and the like.

Step S200 is to form the composite layer 2 on the front surface of the bottom cell 1, and the resulting structure is shown in fig. 5.

In this step, the composite layer 2 includes a tunnel junction or a transparent conductive substance, the tunnel junction can combine the photo-generated electrons generated by the perovskite top cell 3 and the photo-generated holes generated by the bottom cell 1 in the tunnel junction, and for example, the transparent conductive substance may be TCOs, IZO (indium-doped zinc oxide), ITO, a transparent electrode Ag, and the like, which have good photon permeability and conductivity, and can connect the bottom cell 1 and the perovskite top cell 3 to realize ohmic contact, thereby ensuring that the electrons and holes inside the cells are combined, and thereby improving the band gap matching between the bottom cell 1 and the perovskite top cell 3.

Step S300 is to form the perovskite-roof battery 3 on the surface of the composite layer 2.

Step S301 is to form a hole transport layer 31, a perovskite layer 32, and an electron transport layer 33 in this order on the surface of the composite layer 2, and the resulting structure is shown in fig. 6.

In some embodiments, the hole transport layer 31 refers to a layer that extracts and transports holes from photogenerated excitons of the perovskite layer 32, including but not limited to organic based materials, such as 2,2', 7' -tetrakis [ N, N-bis (4-methoxyphenyl) amino]-9,9' -spirobifluorene (Spiro-OMeTAD), poly [ bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine]Any one of (PTAA) and poly 3-hexylthiophene (P3 HT); the inorganic material is CuI, cuSCN, tiO ₂ And SnO ₂ Any one of them.

In some embodiments, the thickness of the hole transport layer 31 is 1nm to 200nm, and the thickness of the hole transport layer 31 may be 1nm, 5nm, 10nm, 20nm, 50nm, 80nm, 100nm, 120nm, 156nm, 170nm, 180nm, 195nm, 200nm, or the like, and the thickness of the hole transport layer 31 is controlled within the above range, which is beneficial to increase of the open-circuit voltage and the fill factor.

In some embodiments, the hole transport layer 31 is formed by any one of magnetron sputtering, high-temperature spray coating, and spin coating.

The perovskite cell refers to a solar cell 100 fabricated using a perovskite layer 32, and the perovskite in the perovskite layer 32 refers to a structure ABX ₃ And crystalline materials of similar structure, wherein:

a is a monovalent cation, including but not limited to Rb ⁺ 、Na ⁺ 、K ⁺ 、Cs ⁺ 、HN＝CHNH ₃ ⁺ (denoted as FA), CH ₃ NH ₃ ⁺ (denoted as MA).

B is a divalent cation comprisingBut is not limited to Sn ²⁺ 、Pb ²⁺ Any one of them.

X is selected from halogen anions (F) ^- 、Cl ^- And Br ^- Etc.), O ^2- 、S ^2- Any one of them.

In the structure, B is positioned at the center of a cubic unit cell body, X is positioned at the center of a cubic face, and A is positioned at the vertex position of the cube. Compared with a structure connected in a common-edge and coplanar manner, the perovskite battery has a more stable structure and is beneficial to diffusion and migration of defects.

Perovskite layer 32 for use in the present application includes, but is not limited to, methylamine lead iodide, (Cs) _x (FA) _1-x PbI ₃ 、(FA) _x (MA) _1-x PbI ₃ 、(FA) _x (MA) _1-x PbI _y Cl _1-y 、(FAPbI ₃ ) _x (MAPbBr ₃ ) _1-x Etc.; wherein x =0 to 1, y =0 to 1.

Upon exposure to sunlight, perovskite layer 32 first absorbs photons to generate electron-hole pairs, which carriers either become free carriers or form excitons due to differences in the binding energy of the perovskite excitons. Furthermore, because these perovskite materials tend to have a lower probability of carrier recombination and higher carrier mobility, the diffusion distance and lifetime of carriers are longer. For example, methylamine lead iodide (CH) ₃ NH ₃ PbI ₃ ) Has a carrier diffusion length of at least 100nm and CH ₃ NH ₃ PbI _3-X Cl _X Even more than 1 μm, x =0 to 1, the solar cell 100 prepared by the perovskite layer 32 can obtain superior performance. Preferably, the perovskite layer material is lead methylamine iodide (CH) ₃ NH ₃ PbI ₃ )。

In some embodiments, the perovskite layer 32 has a thickness of 300nm to 800nm, and the perovskite layer 32 may have a thickness of 300nm, 350nm, 380nm, 420nm, 480nm, 500nm, 600nm, 630nm, 680nm, 700nm, 720nm, 750nm, 800nm, or the like, and the thickness of the perovskite layer 32 may be controlled within the above range, which is advantageous for absorption of light and suppression of carrier recombination.

In some embodiments, the perovskite layer 32 is formed using any one of spin coating, spray coating, knife coating, or evaporation.

The perovskite layer 32 of the present application has the characteristics of low cost and solution preparation, is convenient to prepare by a roll-to-roll technique which does not require vacuum conditions, and is easier to produce than conventional silicon cells.

The electron transport layer 33 (ETM) refers to a layer for extracting and transporting electrons from photogenerated excitons of the perovskite layer 32, and includes, but is not limited to, inorganic materials including, for example, znO and MoO, or polymer materials ₃ Any one of the above; the organic material includes any one of fullerene derivatives (PCBM) and C60.

In some embodiments, the thickness of the electron transport layer 33 is 10nm to 50nm, and the thickness of the electron transport layer 33 may be 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, or the like, and the thickness of the electron transport layer 33 is controlled within the above range, which facilitates electron transport.

In some embodiments, the electron transport layer 33 is formed using any one of spray coating, blade coating, evaporation, or spin coating.

It is understood that the hole transport layer 31, the perovskite layer 32 and the electron transport layer 33 may be prepared by the same method, or may be prepared by different methods.

Step S302 is to form a composite conductive layer on the surface of the electron transit layer 33.

In step S3021, a second conductive layer 342 is formed on the surface of the electron transport layer 33, as shown in fig. 7, the second conductive layer 342 includes a metal conductive film layer 3421 corresponding to the metalized region and a second transparent conductive film layer corresponding to the non-metalized region.

In some embodiments, before forming the second conductive layer 342 on the surface of the electron transport layer 33, the third conductive layer 343 is formed on the surface of the electron transport layer 33, and then the second conductive layer 342 is formed on the surface of the third conductive layer 343, so that the battery structure is shown in fig. 8.

In some embodiments, the third conductive layer 343 includes a transparent conductive film layer including any one of ITO, IZO, and TCO films.

In some embodiments, third conductive layer 343 is formed by a physical vapor deposition process, which may include any one of magnetron sputtering, thermal evaporation, and electron beam physical deposition.

In some embodiments, a screen printing process in combination with a sintering process may be used to form the metal conductive film layer 3421 corresponding to the metalized region and the second transparent conductive film layer 3422 corresponding to the non-metalized region. Of course, the material can also be prepared by a physical vapor deposition process, and the physical vapor deposition process includes any one of magnetron sputtering, thermal evaporation and electron beam physical deposition.

In some embodiments, the metal conductive film layer 3421 is derived from any one of a Ni source, a Cu source, an Al source, a Ni source, a Sn source, a Zn source, an Ag source, and an Au source, and the conductivity of the metal conductive film layer 3421 made of the above materials is greater than that of a transparent conductive film layer (typically ITO, IZO, TCO film, and the like), and the price is low, so that the conductivity of the conductive composite layer 34 is improved while the cost is reduced, thereby reducing the series resistance of the battery, improving the charge transfer capability, improving the short circuit density of the solar cell 100, and also improving the fill factor, thereby effectively improving the photoelectric conversion efficiency of the solar cell 100.

In some embodiments, an etching process may also be used to form the metal conductive film layer 3421 corresponding to the metalized region and the second transparent conductive film layer corresponding to the non-metalized region. That is, a transparent conductive film layer is formed on the surface of the electron transport layer 33, and then the transparent conductive film layer is removed by etching in the metalized region of the transparent conductive film layer, and then the metal conductive film layer 3421 is formed by a deposition process or a screen printing process.

In some embodiments, the second transparent conductive film layer 3422 includes any one of ITO, IZO and TCO thin film.

Step S3022 is to form a first conductive layer 341 on the surface of the second conductive layer 342, and the resulting structure is shown in fig. 9.

In some embodiments, the first conductive layer 341 is formed by any one of a sputtering process and a deposition process.

In some embodiments, the first conductive layer 341 (i.e., the first transparent conductive film layer) includes any one of ITO, IZO, and TCO films. It is understood that the materials of the first transparent conductive film layer and the second transparent conductive film layer 3422 may be the same or different.

In some embodiments, when the first conductive layer 341 and the second conductive layer 342 are provided in 2 or more groups, the steps S3021 and S3022 may be repeated.

In some embodiments, the solar cell 100 of the present application further comprises: that is, step S400 is to form the front electrode 5 on the surface of the composite conductive layer, and the resulting structure is shown in fig. 10.

In some embodiments, the front electrode 5 is prepared by any one of vacuum evaporation, electron beam deposition, electroplating, and screen printing.

In some embodiments, the distance between the transverse grid lines of the front electrode 5 is 1mm to 4mm, specifically, the distance between the transverse grid lines of the front electrode 5 is 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm and 4mm, the distance between the transverse grid lines of the conventional silicon/perovskite battery is generally 0.5mm to 2mm, the distance between the transverse grid lines of the front electrode 5 of the present application is greater than the distance between the conventional transverse grid lines, the electrode usage can be saved, the cost is saved, and the conductivity of the battery is not affected.

In some embodiments, the pitch of the longitudinal grid lines of the front electrode 5 is 1mm to 4mm, and specifically, the pitch of the longitudinal grid lines of the front electrode 5 is 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, and 4mm.

In some embodiments, the ratio of the height of the front electrode 5 to the height of the back electrode 4 is greater than or equal to 10%, specifically, the ratio of the height of the front electrode 5 to the height of the back electrode 4 may be 10%, 15%, 20%, 25%, 30%, 50% and 70%, and controlling the height of the front electrode 5 within the above range indicates that the front electrode 5 is used in a smaller amount to ensure the conductivity of the battery and reduce the manufacturing cost, and preferably, the ratio of the height of the front electrode 5 to the height of the back electrode 4 is 10% to 30%.

In step S400, a back electrode 4 is formed on the back surface of the bottom cell 1, and the solar cell 100 is obtained.

It is understood that the present application can selectively prepare the front electrode 5, that is, the present application can prepare the solar cell 100 without the front electrode 5 and only with the back electrode 4, and the cell structure is shown in fig. 1; the present application also allows the preparation of a solar cell 100 having both front and

back electrodes

5 and 4, the cell structure being shown in fig. 11.

In some embodiments, the material of the back electrode 4 includes any one of Ag and Au.

In some embodiments, the back electrode 4 is prepared by any one of vacuum evaporation, electron beam deposition, electroplating, and screen printing.

In some embodiments, the pitch of the gate lines of the back electrode 4 is 0.2 μm to 3 μm, and specifically, the pitch of the gate lines of the back electrode 4 may be 0.2 μm, 0.5 μm, 1 μm, 2 μm, and 3 μm.

In some embodiments, the height of the back electrode is 20nm to 70nm, and specifically, the height of the back electrode may be 20nm, 30nm, 40nm, 50nm, 60nm, and 70nm.

In a third aspect, the present application provides a photovoltaic module 1000 comprising a string of solar cells as described above formed by electrical connections.

Specifically, referring to fig. 12, the photovoltaic module 1000 includes a first cover plate 200, a first encapsulant layer 300, a solar cell string, a second encapsulant layer 400, and a second cover plate 500.

In some embodiments, the solar cell string includes a plurality of solar cells 100 connected by conductive tapes, and the connection manner between the solar cells 100 may be partial lamination or splicing.

In some embodiments, the first cover plate 200 and the second cover plate 500 may be transparent or opaque cover plates, such as glass cover plates and plastic cover plates.

The two sides of the first packaging adhesive layer 300 are respectively contacted and attached with the first cover plate 200 and the battery string, and the two sides of the second packaging adhesive layer 400 are respectively contacted and attached with the second cover plate 500 and the battery string. The first and second encapsulant layers 300 and 400 may be ethylene-vinyl acetate copolymer (EVA) adhesive films, polyethylene octene co-elastomer (POE) adhesive films, or polyethylene terephthalate (PET) adhesive films, respectively.

The photovoltaic module 1000 may also be encapsulated in a side edge full-enclosure manner, that is, the side edge of the photovoltaic module 1000 is completely encapsulated and encapsulated by using an encapsulation tape, so as to prevent the photovoltaic module 1000 from generating a lamination offset phenomenon in the lamination process.

The photovoltaic module 1000 further includes an edge sealing member, which is fixedly sealed to a portion of the edge of the photovoltaic module 1000. The edge sealing member may be fixedly sealed to the edge of the photovoltaic module 1000 near the corner. The edge sealing member may be a high temperature resistant tape. The high-temperature-resistant adhesive tape has excellent high-temperature-resistant characteristic, cannot be decomposed or fall off in the laminating process, and can ensure reliable packaging of the photovoltaic module 1000. Wherein, two ends of the high temperature resistant adhesive tape are respectively fixed on the second cover plate 500 and the first cover plate 200. The two ends of the high-temperature-resistant adhesive tape can be respectively bonded with the second cover plate 500 and the first cover plate 200, and the middle part of the high-temperature-resistant adhesive tape can limit the side edge of the photovoltaic module 1000, so that the photovoltaic module 1000 is prevented from laminating and deviating in the laminating process.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, comprising:

a bottom cell comprising opposing front and back sides;

a back electrode located on the back side of the bottom cell.

2. The solar cell according to claim 1, wherein the metal conductive film layer is made of any one of Ni, cu, al, ni, sn, zn, ag, and Au.

3. The solar cell according to claim 1, wherein the metal conductive film layer has a thickness of 0.1nm to 10nm.

4. The solar cell of claim 1, wherein the thickness of the conductive composite layer is 20nm to 200nm.

5. The solar cell of claim 1, wherein the conductive composite layer further comprises a third conductive layer between the second conductive layer and the electron transport layer, the third conductive layer comprising a third transparent conductive film layer.

6. The solar cell of claim 1, wherein the thickness of the second conductive layer is greater than the thickness of the first conductive layer.

7. The solar cell of claim 1, further comprising a front side electrode on a surface of the outermost first conductive layer.

8. The solar cell of claim 7, wherein the pitch of the transverse grid lines of the front electrode is 1-4 mm; and/or the longitudinal grid line spacing of the front electrode is 1 mm-4 mm.

9. The solar cell of claim 7, wherein a ratio of a height of the front electrode to a height of the back electrode is 0.1 or greater.

10. A photovoltaic module comprising a plurality of strings of solar cells, each string of solar cells being formed by electrically connecting solar cells according to any one of claims 1 to 9.