Solar cell and laminated solar cell

Abstract

The present application provides a solar cell and a stacked solar cell, the solar cell comprising: a substrate; the first tunneling layer is positioned on one side of the substrate; the first passivation layer is located on the side, away from the substrate, of the first tunneling layer, and the first passivation layer is provided with a plurality of through holes; the hole transport layer is located in the through hole; the perovskite film layer, the electron transport layer, the first transparent conductive layer and the antireflection layer are sequentially stacked on the first passivation layer in the direction, away from the substrate, of the first passivation layer, and the first electrode is located on the side, away from the substrate, of the antireflection layer. The perovskite layer and the first passivation layer are in local contact, so that on the basis of ensuring the passivation effect of the first tunneling layer, the contact area of the hole transport layer and the first tunneling layer is increased, the interface series resistance is reduced, and the problem that the interface series resistance is large in order to meet the passivation effect of the solar cell in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a solar cell and a laminated solar cell. BACKGROUND

[0002] Currently, in order to reduce the non-radiative recombination loss caused by surface defects of the solar cell, it is usually necessary to deposit a passivation layer. However, these passivation materials generally have very low conductivity, and when the passivation layer is thin, the passivation effect is poor; when the passivation layer is thickened, the passivation effect is good, but at the same time, the interface series resistance is increased. In order to solve this problem, the prior art needs to accurately prepare an ultra-thin passivation layer with a thickness of only a few or even one nanometer (nm, one billionth of a meter). This thickness-sensitive and tunneling-effect carrier transport mode has high requirements for process and equipment, and is not conducive to the low-cost mass production of perovskite / silicon laminated solar cells. CONTENT OF THE UTILITY MODEL

[0003] The present application provides a solar cell and a laminated solar cell to solve the problem of large interface series resistance at the passivation site in the related art to meet the passivation effect of the solar cell.

[0004] According to one aspect of the present application, a solar cell is provided, comprising: a substrate; a first tunneling layer located on one side of the substrate; a first passivation layer located on a side of the first tunneling layer away from the substrate, the first passivation layer having a plurality of through holes; a hole transport layer located in the through holes, the hole transport layer being composed of a plurality of hole transport particles; a perovskite film layer, an electron transport layer, a first transparent conductive layer and an anti-reflection layer sequentially stacked on the first passivation layer in a direction away from the substrate; and a first electrode located on a side of the anti-reflection layer away from the substrate, the first electrode being electrically connected to the first transparent conductive layer.

[0005] Optionally, the through holes are diffusion holes of gas generated by a pore-forming agent coated on a side of the first passivation layer close to the substrate.

[0006] Optionally, the pore diameter of the through holes is 50-200 nm.

[0007] Optionally, the area of the surface of the side of the first passivation layer away from the substrate accounts for 20-70% of the area of the surface of the side of the first tunneling layer away from the substrate.

[0008] Optionally, the thickness of the first passivation layer is 11-50 nm.

[0009] Optionally, in a direction of the substrate pointing to the first tunneling layer, the thickness of the first passivation layer is greater than the maximum particle size of the hole transport particles.

[0010] Optionally, the shape of the hole transport particle comprises at least one of the following: a sphere, an ellipsoid and a polyhedron.

[0011] Optionally, the hole transport particles are distributed in the first passivation layer in an array form.

[0012] Optionally, the hole transport particles are irregularly distributed in the first passivation layer.

[0013] According to another aspect of the present application, a laminated solar cell is provided, comprising the solar cell, and the substrate in the solar cell is a heterojunction crystalline silicon bottom cell.

[0014] By the technical solution of the present application, a solar cell is provided, comprising a substrate, a first tunneling layer, a first passivation layer, a hole transport layer, a perovskite film layer, an electron transport layer, a first transparent conductive layer, an anti-reflection layer and a first electrode. The first tunneling layer is located on one side of the substrate. The first passivation layer is located on the side of the first tunneling layer away from the substrate, and the first passivation layer has a plurality of through holes. The hole transport layer is located in the through holes, and the hole transport layer is composed of a plurality of hole transport particles. The perovskite film layer, the electron transport layer, the first transparent conductive layer, the anti-reflection layer and the first electrode are sequentially laminated on the first passivation layer in the direction away from the substrate. By providing a plurality of through holes in the first passivation layer, the hole transport layer is located in the through holes, and the perovskite layer and the first passivation layer are in local contact, thereby improving the contact area of the hole transport layer and the first tunneling layer on the basis of ensuring the passivation effect of the first tunneling layer, and reducing the interface series resistance. The problem of large interface series resistance caused by the passivation effect of the solar cell in the related art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The accompanying drawings should not be construed as an inappropriate limitation on the present application. In the drawings:

[0016] Figure 1 is a cross-sectional structure schematic diagram of a solar cell provided according to an embodiment of the present application;

[0017] Figure 2 is Figure 1 is a cross-sectional structure schematic diagram of a hole transport particle regularly distributed in the first passivation layer in the solar cell of the present application;

[0018] Figure 3 is Figure 1 is a cross-sectional structure schematic diagram of another hole transport particle irregularly distributed in the first passivation layer in the solar cell of the present application;

[0019] Figure 4Figure 1 is a schematic diagram of a cross-sectional structure of a laminated solar cell provided by an embodiment of the present application.

[0020] In the above drawings, the following reference signs apply:

[0021] 1, substrate; 2, first tunneling layer; 3, first passivation layer; 4, hole transport layer; 5, perovskite film layer; 6, electron transport layer; 7, first transparent conductive layer; 8, anti-reflection layer; 9, first electrode; 10, base; 11, n-type hydrogenated amorphous silicon layer; 12, first intrinsic hydrogenated amorphous silicon layer; 13, second intrinsic hydrogenated amorphous silicon layer; 14, p-type hydrogenated amorphous silicon layer; 15, second transparent conductive layer; 16, second electrode; 17, buffer layer. DETAILED DESCRIPTION

[0022] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0023] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0024] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units need not be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0025] Perovskite / crystalline silicon tandem solar cells combine the advantages of single crystal silicon and perovskite, and have achieved an certified efficiency of 33.9%, which is a promising next-generation photovoltaic technology. For photovoltaic devices, interface problems are crucial. Therefore, interface passivation as a major strategy to reduce interface defects of perovskite photovoltaic devices has been extensively studied. For perovskite / crystalline silicon tandem solar cells, there are generally a large number of surface defects at the interface between the perovskite film and the hole transport layer, which are carrier recombination centers.

[0026] To reduce the loss of non-radiative recombination caused by surface defects, it is usually necessary to deposit a passivation layer. However, these passivation materials are generally low in electrical conductivity, and the passivation effect is poor when the passivation layer is thin; when the passivation layer is thickened, the passivation effect becomes better, but at the same time the interface series resistance is increased.

[0027] The prior art requires the accurate preparation of an ultra-thin passivation layer with a thickness of only a few or even one nanometer (nm, one billionth of a meter). This thickness-sensitive, tunneling effect carrier transport method has high requirements for processes and equipment, which is not conducive to the low-cost mass production of perovskite / silicon tandem solar cells. To solve the above problems, the design field of crystalline silicon solar cells will adopt local contact technology, such as passivation local hole contact of dielectric layers such as silicon oxide, aluminum oxide, and silicon nitride, which generally uses laser drilling technology. The passivation layer hole is a high-cost and low-yield technology, and laser drilling is the most mature process at present, but the laser scanning technology is limited in its industrial application in terms of cost and speed, as well as the damage to the silicon wafer caused by local heat. In addition, because the photogenerated carrier lifetime of the perovskite thin film is much lower than that of the crystalline silicon, the size of the hole is required to be in the nanometer scale, and laser drilling is difficult to meet the requirements.

[0028] Therefore, research is conducted on the above problems, and as shown in Figure 1 A solar cell is provided in the embodiments of the present application, which includes a substrate 1, a first tunneling layer 2 located on one side of the substrate 1, a first passivation layer 3 located on the side of the first tunneling layer 2 away from the substrate 1, the first passivation layer 3 having a plurality of through holes, a hole transport layer 4 located in the through holes, the hole transport layer 4 being composed of a plurality of hole transport particles, a perovskite film layer 5, an electron transport layer 6, a first transparent conductive layer 7, and an anti-reflection layer 8 sequentially stacked on the first passivation layer 3 in the direction away from the substrate 1, and a first electrode 9 located on the side of the anti-reflection layer 8 away from the substrate 1, the first electrode 9 being electrically connected to the first transparent conductive layer 7.

[0029] By providing a plurality of through holes in the first passivation layer, the hole transport layer is located in the through holes, and the perovskite layer is in local contact with the first passivation layer, thereby improving the contact area of the hole transport layer and the first tunneling layer while ensuring the passivation effect of the first tunneling layer, reducing the interface series resistance, and solving the problem of large interface series resistance caused by the passivation effect of the solar cell in the related art.

[0030] In the above optional implementation, as shown in Figure 1 The substrate 1 can be any one or more of silicon, monocrystalline silicon, and polycrystalline silicon, and can also be a bottom cell for preparing a stacked solar cell, which is not limited in the present application.

[0031] In the above optional implementation, as shown in Figure 1As shown, the material of the hole transport layer 4 can be poly(3,4-ethylenedioxythiophene) and organic semiconductor materials similar to the material, the main role of the hole transport layer 4 can help charge transmission in the device, increase the mobility of the carrier and reduce the recombination rate of the carrier, thereby improving the performance and efficiency of the device, the hole transport layer 4 can also effectively prevent charge recombination and leakage, improve the stability and reliability of the device, and the selection of the material of the hole transport layer 4 is not limited in the present application.

[0032] In the optional embodiment described above, as Figure 1 As shown, the first tunneling layer 2, the first passivation layer 3, the hole transport layer 4, the perovskite film layer 5, the electron transport layer 6, the first transparent conductive layer 7 and the anti-reflection layer 8 can be single-sided texturing or double-sided texturing. The texturing method can be any one of acid texturing, alkali texturing, electrochemical texturing, reactive ion etching texturing, laser texturing and mask texturing, which forms a small textured structure on the surface of the silicon wafer through different chemical or physical processes, thereby improving the conversion efficiency of light energy. The texturing process includes: acid texturing: using an acidic solution to treat the silicon wafer, forming a small concave-convex structure on the surface of the silicon wafer through a chemical reaction, increasing the surface area; alkali texturing: using an alkaline solution to treat the silicon wafer, forming a textured structure on the surface of the silicon wafer through a chemical reaction; electrochemical texturing: forming a specific structure on the surface of the silicon wafer through an electrochemical reaction; reactive ion etching texturing: using reactive ion etching technology to form a small concave-convex structure on the surface of the silicon wafer; laser texturing: using laser technology to form a specific textured structure on the surface of the silicon wafer; mask texturing: protecting part of the area of the silicon wafer from treatment through mask technology, thereby forming a textured structure in the specific area.

[0033] In the optional embodiment described above, as Figure 1 As shown, the material of the first electrode 9 can be any one or more of Ag, Cu and Au, and those skilled in the art can also reasonably select the type of material of the first electrode according to actual needs, which is not limited in the present application.

[0034] In some optional embodiments, as Figure 1 As shown, the through hole is a diffusion hole of the gas generated by the pore-forming agent coated on the side of the first passivation layer 3 close to the substrate 1.

[0035] In the above optional embodiments, a pore-forming layer is deposited on the first tunneling layer to create diffusion pores for the gas generated by the pore-forming agent. A first passivation layer is deposited uniformly on the pore-forming layer, and a heterojunction single-crystal silicon substrate containing a dense insulating passivation layer, a pore-forming layer, and a first tunneling layer is heated to generate pore-forming gas and obtain the first passivation layer. A monolayer hole transport material containing anchoring groups is deposited on the first passivation layer. Using a substance that can volatilize and generate gas after heating as a via can significantly reduce the complexity of the process, and the preparation process is low in cost and can be mass-produced.

[0036] In the above optional embodiments, the first passivation layer can be any one or more of sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), ammonium bicarbonate (NH4HCO3), ammonium chloride (NH4Cl), ammonium carbonate (NH4)2CO3, and diammonium hydrogen phosphate (NH4)2HPO3, used to prepare tandem solar cells, and this application does not make specific limitations.

[0037] In some alternative implementations, the aperture of the via is 50 nm to 200 nm.

[0038] In the above optional embodiments, by placing the hole transport layer in the via, the perovskite layer and the hole transport layer are no longer in complete contact, but in partial contact. This reduces the recombination of interfacial carriers caused by direct contact between the perovskite film layer and the hole transport layer, and reduces the series resistance loss in the traditional non-local contact passivation method.

[0039] In some alternative implementations, such as Figure 1 As shown, the area of ​​the surface of the first passivation layer 3 facing away from the substrate 1 accounts for 20% to 70% of the area of ​​the surface of the first tunneling layer 2 facing away from the substrate 1.

[0040] In the above optional embodiments, the area missing from the first passivation layer forms a via, and the hole transport layer is placed in the aforementioned pupil. By adjusting the area ratio between the first passivation layer and the first tunneling layer, i.e., adjusting the contact area between the hole transport layer and the perovskite layer, the growth position of the perovskite crystal nucleus can be effectively controlled, reducing the recombination of interfacial carriers caused by direct contact between the perovskite and the hole transport layer, promoting the conformal growth of the perovskite thin film, thereby improving the photoelectric conversion efficiency.

[0041] In some alternative implementations, such as Figure 1 As shown, the thickness of the first passivation layer 3 is 11 nm to 50 nm.

[0042] In the above optional embodiments, the thickness range is within the above range, which can make the thickness of the first passivation layer higher than the thickness of the monolayer hole transport material containing anchoring groups, so that the first passivation layer is equivalent to many protrusions, and the perovskite crystal nuclei will preferentially form on the protruding insulating passivation material, thereby promoting the conformal growth of the perovskite film.

[0043] In the above optional embodiments, the first passivation layer can be any one or more of Al2O3, SiO2 and ZrO2, and is distributed in a random mesh-like porous pattern on the first tunneling layer for the fabrication of stacked solar cells. This application does not make specific limitations.

[0044] In some alternative implementations, such as Figure 1 As shown, in the direction from the substrate 1 to the first tunneling layer 2, the thickness of the first passivation layer 3 is greater than the maximum particle size of the hole transport particles.

[0045] In the above optional embodiments, the thickness of the first passivation layer is greater than the thickness of the monolayer hole transport material containing anchoring groups, making the first passivation layer equivalent to numerous protrusions. Perovskite nuclei will preferentially form on the protruding insulating passivation material, thereby promoting conformal growth of the perovskite thin film. Alternatively, the thickness of the first passivation layer can be greater than the maximum particle size of the hole transport particles, effectively preventing hole transport particles from penetrating into the first tunneling layer, thereby reducing energy loss and improving the efficiency of the solar cell.

[0046] In some alternative implementations, the shape of the hole-transmitting particles includes at least one of the following: sphere, ellipsoid, and polyhedron.

[0047] In the above optional embodiments, the preparation method of the hole transport particles can be any one or more of slit coating, pneumatic spraying, electrostatic spraying and inkjet printing technologies. The preparation material is low in cost and easy to obtain, and presents a discontinuous distribution morphology of island, dot or rod, which is used to prepare tandem solar cells. This application does not make specific limitations.

[0048] In some alternative implementations, such as Figure 1 and Figure 2 As shown, hole transport particles are distributed in an array in the first passivation layer 3.

[0049] In the above optional embodiments, the hole transport particles in the hole transport layer 4 can be distributed in an array in the first passivation layer, or they can be distributed as follows: Figure 3 The disordered distribution shown can increase the contact area between the first electrode and the hole transport layer, increase the extraction efficiency of photogenerated carriers, and thus improve the photoelectric conversion efficiency of the solar cell.

[0050] In some alternative implementations, such as Figure 1and Figure 3 As shown in the figure, the hole transport particles are irregularly distributed in the first passivation layer 3.

[0051] In the optional embodiment described above, when the hole transport particles are irregularly distributed in the first passivation layer, the roughness of the surface of the first electrode can be increased, the light absorption capacity can be improved, the amount of photo-generated carriers can be increased, and thus the photoelectric conversion efficiency of the solar cell can be improved.

[0052] In the embodiments of the present application, a laminated solar cell is also provided, as shown in the figure, which comprises the solar cell described above, and the substrate 1 in the solar cell is a heterojunction crystalline silicon bottom cell. Figure 4 As shown in the figure, the hole transport particles are irregularly distributed in the first passivation layer 3.

[0053] In the optional embodiment described above, the solar cell (top cell) in the laminated solar cell described above is deposited with a pore-forming layer on the first tunneling layer in the direction away from the substrate, and a uniformly covered first passivation layer is deposited, and then the heterojunction monocrystalline silicon substrate containing the first passivation layer, the pore-forming layer and the first tunneling layer is heated to generate pore-forming gas, so as to obtain a first passivation layer with a random network of porous distribution. The single-molecule layer hole transport material containing an anchoring group has the characteristics of low cost and easy availability, which can greatly reduce the process complexity of opening the passivation layer, enable the perovskite and the hole transport layer to be locally contacted, thereby reducing the interface carrier recombination caused by the direct contact between the perovskite layer and the hole transport layer, and reducing the series resistance loss in the non-local contact passivation mode.

[0054] As shown in the figure, the hole transport particles are irregularly distributed in the first passivation layer 3. Figure 4 As shown in the figure, the hole transport particles are irregularly distributed in the first passivation layer 3. Figure 1 The description of the top cell of the laminated solar cell can be referred to the description in the figure, and the heterojunction crystalline silicon bottom cell can be used as the substrate of the top cell.

[0055] As shown in the figure, the hole transport particles are irregularly distributed in the first passivation layer 3. Figure 4As shown, there can be a buffer layer 17 between the first transparent conductive layer 7 and the anti-reflection layer 8 of the top cell, which can smooth the interface between the two layers, reduce interface reflection and scattering, and thus improve the light transmission efficiency. This can increase the amount of photon absorption in the solar cell and improve the photoelectric conversion efficiency. It can also prevent chemical reaction or electron migration between the first transparent conductive layer 7 and the anti-reflection layer 8, thereby protecting the stability and life of the entire structure. This can prolong the service life of the solar cell and improve reliability.

[0056] The material of the buffer layer described above can be any one or more of indium tin oxide (ITO), aluminum oxide (Al2O3), silicon nitride (SiNx), copper indium gallium selenide (CIGS), copper indium gallium sulfide (CIGS), zinc oxide (ZnO), and tin oxide (SnO2).

[0057] From the above description, it can be seen that the above-described embodiments of the present application achieve the following technical effects:

[0058] The above-described solar cell using the embodiments of the present application includes a substrate, a first tunneling layer, a first passivation layer, a hole transport layer, a perovskite film layer, an electron transport layer, a first transparent conductive layer, an anti-reflection layer, and a first electrode. A substance that can generate gas after heating is used as a pore-forming agent, which greatly reduces the process complexity. By making the thickness of the first passivation layer greater than the maximum particle size of the hole transport particles, the perovskite crystal nucleus can be preferentially formed on the protruding insulating passivation material, which promotes the conformal growth of the perovskite thin film, thereby reducing energy loss and improving the efficiency of the solar cell.

[0059] It should also be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles, or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or other elements inherent to such processes, methods, articles, or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element.

[0060] The above is only an embodiment of the present application and is not intended to limit the present application. Those skilled in the art can make various changes and modifications to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A solar cell, characterized in that, include; Substrate; The first tunneling layer is located on one side of the substrate; A first passivation layer is located on the side of the first tunneling layer opposite to the substrate, and the first passivation layer has a plurality of vias; A hole transport layer is located in the via, and the hole transport layer is composed of multiple hole transport particles; Along the direction opposite to the substrate of the first passivation layer, a perovskite film layer, an electron transport layer, a first transparent conductive layer and an anti-reflection layer are sequentially stacked on the first passivation layer; The first electrode is located on the side of the antireflective layer opposite to the substrate, and the first electrode is electrically connected to the first transparent conductive layer.

2. The solar cell according to claim 1, characterized in that, The via is a diffusion hole for gas generated by the pore-forming agent coated on the side of the first passivation layer near the substrate.

3. The solar cell according to claim 2, characterized in that, The aperture of the through hole is 50nm to 200nm.

4. The solar cell according to claim 1, characterized in that, The area of ​​the surface of the first passivation layer facing away from the substrate accounts for 20% to 70% of the area of ​​the surface of the first tunneling layer facing away from the substrate.

5. The solar cell according to claim 1, characterized in that, The thickness of the first passivation layer is 11 nm to 50 nm.

6. The solar cell according to claim 1, characterized in that, In the direction of the substrate pointing towards the first tunneling layer, the thickness of the first passivation layer is greater than the maximum particle size of the hole transport particles.

7. The solar cell according to claim 1, characterized in that, The shape of the hole-transmitting particle includes at least one of the following: sphere, ellipsoid, and polyhedron.

8. The solar cell according to claim 1, characterized in that, The hole transport particles are distributed in an array within the first passivation layer.

9. The solar cell according to claim 1, characterized in that, The hole transport particles are irregularly distributed in the first passivation layer.

10. A tandem solar cell, characterized in that, The solar cell includes any one of claims 1 to 9, wherein the substrate of the solar cell is a heterocrystalline silicon substrate.

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