Solar cell and manufacturing method therefor, photovoltaic power generation system, and electric device

Abstract

A solar cell and a manufacturing method therefor, a photovoltaic power generation system, and an electric device. The solar cell comprises a conductive base layer, a first light absorption layer arranged on the conductive base layer, and a first electron transport layer stacked with the first light absorption layer. The band gap width of the first light absorption layer ranges from 0.90 eV to 1.60 eV. For the solar cell, there is no need to provide a hole transport layer between the conductive base layer and the first light absorption layer, thereby simplifying the structure and the manufacturing process of a solar cell device, and reducing the time and costs for manufacturing the solar cell; in addition, the obtained solar cell also has high photoelectric conversion efficiency.

Description

Solar cell and preparation method thereof, photovoltaic power generation system and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410268644.2, filed on March 8, 2024, entitled “Solar cells and methods for preparing the same, photovoltaic power generation systems and electrical equipment,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of new energy technologies, and in particular to solar cells and methods for preparing the same, photovoltaic power generation systems, and electrical equipment. Background Art

[0004] As a key technology in the field of new energy, solar cells have expanded beyond the military and aerospace sectors into numerous fields, including industry, commerce, agriculture, communications, home appliances, and public utilities. Perovskite solar cells are one of the most promising and promising solar cells, boasting high efficiency, environmental friendliness, and low cost.

[0005] Currently, perovskite solar cells typically have a separate hole transport layer in their structure, resulting in a complex manufacturing process, long manufacturing time, and high manufacturing costs. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art.

[0006] Summary of the Invention

[0007] The main technical problem solved by this application is to provide a solar cell and its preparation method, a photovoltaic power generation system and electrical equipment, which can simplify the solar cell device structure and preparation process, reduce the time and cost of solar cell preparation, and at the same time, the obtained solar cell also has a high photoelectric conversion efficiency.

[0008] To solve the above technical problems, the present application adopts a technical solution: providing a solar cell comprising a conductive substrate, a first light-absorbing layer disposed on the conductive substrate, and a first electron transport layer stacked with the first light-absorbing layer; the band gap width of the first light-absorbing layer is 0.90eV-1.60eV. With this arrangement, a hole transport layer need not be disposed between the conductive substrate and the first light-absorbing layer of the solar cell, which can simplify the device structure and preparation process of the solar cell, reduce the time and cost of solar cell preparation, and simultaneously achieve a high photoelectric conversion efficiency.

[0009] In one embodiment, the conductive base layer is a first electrode, and the solar cell includes the first electrode, a first light absorbing layer disposed on the first electrode, and a first electron transport layer and a second electrode stacked on the first light absorbing layer. In this embodiment, the solar cell is a single-junction solar cell, and a hole transport layer is not required between the first electrode and the first light absorbing layer of the solar cell. This simplifies the device structure and preparation process of the single-junction solar cell, reduces the time and cost of solar cell preparation, and also achieves a high photoelectric conversion efficiency.

[0010] In one embodiment, the conductive base layer is an interjunction conductive layer, and the solar cell further includes a second light absorbing layer disposed on a side of the interjunction conductive layer away from the first light absorbing layer. In this embodiment, the solar cell is a tandem solar cell, and a hole transport layer need not be disposed between the interjunction conductive layer and the first light absorbing layer of the solar cell. This simplifies the device structure and fabrication process of the tandem solar cell, and reduces the time and cost of solar cell fabrication.

[0011] In one embodiment, the second light absorbing layer has a bandgap width of 1.60 eV to 2.50 eV. The second light absorbing layer has a wider bandgap than the first light absorbing layer. Stacking two light absorbing layers with different bandgaps enables the tandem solar cell to more fully utilize various wavelengths of the solar spectrum, achieving spectral complementarity and improving photon utilization. Furthermore, by combining the advantages of different types of solar cells, the resulting effects complement each other, thereby improving photoelectric conversion efficiency.

[0012] In one embodiment, the solar cell further comprises a second electron transport layer disposed between the interjunction conductive layer and the second light absorbing layer; and a hole transport layer disposed on a side of the second light absorbing layer away from the second electron transport layer. The electron transport layer can enhance electron transport, and the hole transport layer can enhance hole transport. The second electron transport layer and the hole transport layer can reduce non-radiative carrier recombination caused by direct contact between the second light absorbing layer and the electrode and the interjunction conductive layer.

[0013] In one embodiment, a solar cell includes a first electrode, a hole transport layer stacked with the first electrode, a second light absorbing layer, a second electron transport layer, an interjunction conductive layer, a first light absorbing layer disposed on the interjunction conductive layer, and a first electron transport layer and a second electrode stacked with the first light absorbing layer. In this embodiment, the solar cell is a tandem solar cell comprising two solar sub-cells, which can improve photon utilization and photoelectric conversion efficiency. Furthermore, at least one solar sub-cell can be provided without a hole transport layer, which optimizes the manufacturing process, simplifies the solar cell device structure, and improves the stability of the top sub-cell, thereby improving the stability of the solar cell.

[0014] In one embodiment, the first light absorbing layer contains additives, the additives comprising At least one of the following: wherein R1 comprises a carbon chain having 1-12 carbon atoms; R2 comprises any one of a thiol group, an amino group, and an aryl group; and X comprises any one of an iodide ion, a chloride ion, a bromide ion, a tetrafluoroborate ion, and a thiocyanate ion. These additives can promote hole extraction and passivate defects in the first light-absorbing layer. Thus, while simplifying the solar cell device structure, they can also maintain solar cell performance, improving short-circuit current, open-circuit voltage, and photoelectric conversion efficiency.

[0015] In one embodiment, the additive includes one or more of 5-aminopentanoic acid hydrobromide, 2-aminoethyl acid hydrobromide, 7-aminoheptyl acid hydrobromide, 12-aminododecanoic acid hydrobromide, 5-aminopentanoic acid hydroiodide, 5-aminolevulinic acid hydrochloride, 5-aminopentanoic acid hydrogen hydrochloride, 5-amino-5-phenylpentane hydrochloride, and 5-aminopentanoic acid. These additives can promote hole extraction and passivate defects in the first light absorption layer, thereby simplifying the solar cell device structure while taking into account the performance of the solar cell, thereby facilitating improvements in short-circuit current, open-circuit voltage, and photoelectric conversion efficiency.

[0016] In one embodiment, the first light absorbing layer comprises a perovskite material APb y Sn 1-y X3, 0<y<1; A includes organic amine ions and Cs + One or more of; X includes Cl - Br - and I - By adjusting the components of the perovskite material, after part of the lead element is replaced by tin, the band gap of the perovskite material becomes narrower, and thus the absorption spectrum becomes wider, thereby improving the light absorption capacity of the first light absorption layer.

[0017] In one embodiment, the perovskite material APb y Sn 1-y The total molar amount of Pb and Sn in X3 is less than or equal to 5% of the total molar amount of the additive. Within this range, the additive doping ratio can promote hole extraction and passivate defects in the light absorption layer while reducing the effect of the additive on the conductivity of the first light absorption layer.

[0018] In one embodiment, the solar cell further includes a hole-blocking layer disposed between the first electron transport layer and the second electrode. The hole-blocking layer comprises one or more of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline, tin dioxide, zinc oxide, and cerium oxide. The thickness of the hole-blocking layer is 5 nm to 15 nm. The hole-blocking layer has a low valence band energy level, effectively preventing hole injection. This reduces energy and charge losses caused by interfacial charge recombination, thereby improving the device's energy conversion efficiency.

[0019] To solve the above technical problems, another technical solution adopted in this application is: to provide a method for preparing a solar cell, comprising: providing a conductive base layer; disposing a light absorption layer precursor liquid on the conductive base layer to form a first light absorption layer, the band gap width of the first light absorption layer being 0.90 eV-1.60 eV; and disposing a first electron transport layer on the first light absorption layer. In the solar cell prepared by the above method, no hole transport layer is disposed between the conductive base layer and the first light absorption layer, thereby simplifying the device structure and preparation process of the solar cell, and reducing the time and cost of solar cell preparation. At the same time, the obtained solar cell also has a high photoelectric conversion efficiency.

[0020] In one embodiment, the light absorbing layer precursor solution further comprises an additive, the additive comprising At least one of the following, wherein R1 comprises a carbon chain having 1-12 carbon atoms; R2 comprises any one of a thiol group, an amino group, and an aryl group; and X comprises any one of an iodide ion, a chloride ion, a bromide ion, a tetrafluoroborate ion, and a thiocyanate ion. Including these additives in the first light-absorbing layer can promote hole extraction and passivate defects in the first light-absorbing layer. This simplifies the solar cell device structure while maintaining solar cell performance, improving short-circuit current and open-circuit voltage, and enhancing photoelectric conversion efficiency.

[0021] In one embodiment, the first light-absorbing layer comprises a perovskite material. The precursor solution for the light-absorbing layer comprises a mixed solution of formamidine iodine, methylamine iodine, lead iodide, stannous iodide, and stannous fluoride. The solvent of the solution comprises N,N-dimethylformamide and dimethyl sulfoxide. Among light-absorbing materials, perovskite materials offer the advantages of low cost and high photoelectric conversion efficiency. Furthermore, perovskite materials can achieve bandgap control by adjusting their composition to meet diverse application requirements.

[0022] In one embodiment, the step of applying the light absorbing layer precursor solution to the conductive base layer includes: providing the light absorbing layer precursor solution and spin coating the light absorbing layer precursor solution on the conductive base layer to form the first light absorbing layer. The spin coating method is simple and efficient, and the prepared light absorbing layer film is relatively uniform.

[0023] In one embodiment, the step of spin-coating a light-absorbing layer precursor solution on a conductive substrate to form a first light-absorbing layer includes: performing spin coating in two steps: the first step is performed at a spin-coating speed of 2000-6000 rpm for 5-20 seconds; and the second step is performed at a spin-coating speed of 3000-6000 rpm for 30-90 seconds. The lower spin-coating speed in the first step facilitates evenly disposing the light-absorbing layer precursor solution on the conductive substrate; the addition of an anti-solvent during the second step facilitates rapid extraction of the solvent from the light-absorbing layer precursor solution, promoting the nucleation and growth of light-absorbing material seed crystals.

[0024] To solve the above technical problems, another technical solution adopted by the present application is to provide a photovoltaic power generation system, comprising any of the above solar cells. The photovoltaic power generation system has at least the same advantages as the solar cell.

[0025] To solve the above technical problems, another technical solution adopted by the present application is to provide an electrical device comprising any of the above solar cells. The electrical device has at least the same advantages as the solar cell.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] FIG1 is a schematic structural diagram of a single-junction solar cell according to one or more embodiments;

[0029] FIG2 is a schematic structural diagram of a tandem solar cell according to one or more embodiments;

[0030] FIG3 is a schematic diagram of the solar cell structure according to Comparative Example 1 and Example 1;

[0031] FIG4 is a schematic diagram of the solar cell structure according to Comparative Example 2 and Example 2;

[0032] In the attached figure:

[0033] 100. Single-junction solar cell; 200. Tandem solar cell; 11. First electrode; 12. Interjunction conductive layer; 13. Second electrode; 21. Hole transport layer; 22. First electron transport layer; 23. Second electron transport layer; 31. First light absorption layer; 32. Second light absorption layer. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and effect of this application clearer and more specific, the following embodiments of the technical solution of this application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0036] In the description of the embodiments of the present application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0037] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0038] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0039] Amounts, ratios, and other numerical values ​​are presented herein in a range format. It should be understood that such range format is used for convenience and brevity and should be interpreted flexibly to include not only the values ​​explicitly specified as range limits, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0040] If not otherwise specified, all steps of the present application may be performed sequentially, randomly, or in parallel, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially, or may include steps (a) and (b) performed simultaneously in parallel. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0041] As a key technology in the field of new energy, solar cells have expanded from military and aerospace applications into numerous fields, including industry, commerce, agriculture, communications, household appliances, and public utilities. Perovskite solar cells (PSCs) are one of the most promising solar cells, boasting high efficiency, environmental friendliness, and low cost.

[0042] Currently, solar cells typically require a separate layer of material as a hole transport layer to improve hole transport efficiency. On the one hand, this complicates the solar cell manufacturing process, prolongs the manufacturing time, and increases the manufacturing cost, hindering the commercial mass production of solar cells. On the other hand, during the use of solar cells, the hole transport layer material may experience performance degradation due to increased temperature. For example, in perovskite solar cells, the commonly used hole transport layer material is poly (3,4-ethylenedioxythiophene:polystyrene sulfonate) (PEDOT:PSS). PEDOT:PSS itself is an acidic solution with poor thermal stability. When the perovskite solar cell device is operated for a long time, the device performance will be significantly reduced.

[0043] Research has found that developing a high-performance solar cell device structure without a hole transport layer is an effective way to solve the above problems.

[0044] Based on this, the present application provides a solar cell, which includes a conductive base layer, a first light absorption layer arranged on the conductive base layer, and a first electron transport layer stacked with the first light absorption layer; the band gap width of the first light absorption layer is 0.90eV-1.60eV.

[0045] The first light absorbing layer is used to absorb light and directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. The first electron transport layer is used to efficiently transport free electrons generated by the first light absorbing layer and effectively block the passage of free holes.

[0046] In one embodiment, there is no other functional layer between the first light absorbing layer and the first electron transporting layer, that is, the first electron transporting layer is adjacent to a side of the first light absorbing layer away from the conductive base layer.

[0047] In another embodiment, other functional layers, such as a passivation layer, a hole blocking layer, etc., are provided between the first light absorbing layer and the first electron transport layer. The functional layers are beneficial to improving the interface transport performance of the solar cell.

[0048] In one embodiment, the first light absorbing layer has a narrow band gap, so that its energy level is relatively matched to that of the conductive base layer, and no hole transport layer is provided between the conductive base layer and the first light absorbing layer. This simplifies the device structure and preparation process of the solar cell, and reduces the time and cost of solar cell preparation. Furthermore, since the preparation of the hole transport layer is omitted, the long high-temperature annealing step in the preparation of the hole transport layer is eliminated, thereby effectively reducing the performance degradation caused by high temperature and improving the stability of the solar cell.

[0049] In one embodiment, no hole transport layer or other functional layers are disposed between the conductive base layer and the first light absorbing layer, i.e., the first light absorbing layer is immediately adjacent to the conductive base layer. In other embodiments, no hole transport layer is disposed between the conductive base layer and the first light absorbing layer, but other functional layers, such as a passivation layer or an electron blocking layer, may be disposed.

[0050] In one embodiment, the conductive base layer is a first electrode. The first electrode is a transparent conductive substrate with high conductivity and high visible light transmittance, and functions to collect positive charges. When the band gap width of the first light absorbing layer is 0.90 eV-1.60 eV, a narrower band gap is selected to relatively match its energy level with that of the first electrode. In the absence of a hole transport layer, this improves the transport performance of holes from the first light absorbing layer to the first electrode, reduces non-radiative recombination of carriers at the interface between the first light absorbing layer and the first electrode, thereby reducing hole loss and improving the photoelectric conversion efficiency of the solar cell.

[0051] In another embodiment, the conductive base layer is an interjunction conductive layer, or in other words, a tunnel junction. The tunnel junction is used to connect two different solar sub-cells to enable recombination of electrons and holes from different solar sub-cells. When the first light absorption layer has a bandgap of 0.90 eV to 1.60 eV, it can absorb lower-energy photons and can be combined with a solar sub-cell having a wider bandgap light absorption layer, thereby improving the utilization of the solar spectrum and thereby enhancing the photoelectric conversion efficiency of the solar cell.

[0052] In one embodiment, when the solar cell is a single-junction solar cell, the conductive base layer is the first electrode. Please refer to FIG1 , which is a schematic diagram of the structure of a single-junction solar cell according to one or more embodiments of the present application. As shown in FIG1 , the single-junction solar cell 100 includes a first electrode 11, a first light absorbing layer 31 disposed on the first electrode 11, and a first electron transport layer 22 and a second electrode 13 stacked on the first light absorbing layer 31. In this embodiment, the single-junction solar cell 100 does not have a hole transport layer disposed between the first electrode 11 and the first light absorbing layer 31.

[0053] The first electrode 11 is a transparent conductive substrate with high conductivity and high visible light transmittance. It functions as a charge collector and has a thickness of 10 nm to 1000 nm. The first light absorbing layer 31 absorbs light and directly converts light energy into electrical energy through the photoelectric effect or photochemical effect. The thickness of the first light absorbing layer 31 is 200 nm to 1000 nm; for example, it can be 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, etc. The first electron transport layer 22 efficiently transports free electrons generated by the first light absorbing layer 31, effectively blocks the passage of free holes, and forms an ohmic contact with the first light absorbing layer 31 at the interface. The thickness of the first electron transport layer 22 is 15 nm to 50 nm, and can be 20 nm, 25 nm, 35 nm, etc. The second electrode 13 functions as a free charge collector and has a thickness of 50 nm to 200 nm, and can be 60 nm, 80 nm, 100 nm, etc.

[0054] The single-junction solar cell device with the above structure does not have a hole transport layer between the first electrode and the first light-absorbing layer, thereby simplifying the device structure and manufacturing process, and reducing the time and cost of solar cell production. Furthermore, the probability of solar cell performance degradation caused by ambient temperature is reduced, which can broaden the application environment and extend the service life of the solar cell.

[0055] In one embodiment, the solar cell further includes a hole blocking layer (not shown) disposed between the first electron transport layer 22 and the second electrode 13; the hole blocking layer comprises a material comprising 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP), tin dioxide (SnO2), zinc oxide (ZnO), cerium oxide (CeO x1 , 1.5≤x1≤2), which may be one or more of BCP and SnO2; the thickness of the hole blocking layer is 5nm-15nm, and may be 7nm, 9nm, 11nm, etc. The hole blocking layer has a low valence band energy level, which can effectively prevent hole injection; thus, it can reduce energy and charge losses caused by interfacial charge recombination, thereby improving the energy conversion efficiency of the device.

[0056] In one embodiment, when the solar cell is a tandem solar cell, the conductive base layer is an interjunction conductive layer, and the solar cell further includes a second light absorbing layer disposed on a side of the interjunction conductive layer away from the first light absorbing layer.

[0057] Among them, the interjunction conductive layer is a tunnel junction, which can also be called an interconnection layer, a charge recombination junction, etc. The tunnel junction is a PN structure that can generate a tunneling current and connect two solar sub-cells to form a tandem solar cell. A tandem solar cell can be composed of two solar sub-cells with light absorption layers of different band gaps. Through the differentiation of the band gap, it can absorb sunlight of a wider range of wavelengths, reduce photon thermal loss, and break the SQ limit (Shockley-Queisser limit) efficiency of a single-junction solar cell. Depending on the material of the light absorption layer, there are different types of tandem solar cells, including all-perovskite tandem solar cells, perovskite / crystalline silicon tandem solar cells, silicon-based tandem solar cells, perovskite / organic tandem solar cells, etc.

[0058] In one embodiment, the second light-absorbing layer has a bandgap of 1.60 eV to 2.50 eV. Compared to the first light-absorbing layer, the second light-absorbing layer has a wider bandgap, allowing it to absorb higher-energy photons. The remaining lower-energy photons pass through the sub-cell to the solar sub-cell with the first light-absorbing layer, which has a narrower bandgap and therefore absorbs lower-energy photons. By stacking two sub-cells with different bandgaps, a tandem solar cell can broaden the range of the solar spectrum it can absorb, improving energy utilization and photoelectric conversion efficiency.

[0059] In one embodiment, the solar cell further includes a second electron transport layer disposed between the interjunction conductive layer and the second light absorbing layer; and a hole transport layer disposed on a side of the second light absorbing layer away from the second electron transport layer.

[0060] The second light-absorbing layer has a wide bandgap and a low energy level match with the electrode material. The hole transport layer facilitates hole transport and prevents free holes from diffusing in the opposite direction, improving the interfacial transport performance between the second light-absorbing layer and the electrode. The thickness of the hole transport layer ranges from 0.5nm to 50nm.

[0061] The second electron transport layer can efficiently transport the free electrons generated by the second light absorbing layer, effectively block the passage of free holes, and form an ohmic contact at the interface with the second light absorbing layer. The thickness of the second electron transport layer is 5nm-100nm.

[0062] In one embodiment, please refer to FIG2 , which is a schematic diagram of the structure of a tandem solar cell according to one or more embodiments of the present application. As shown in FIG2 , the tandem solar cell 200 includes a first electrode 11, a hole transport layer 21 stacked with the first electrode 11, a second light absorbing layer 32, a second electron transport layer 23, an interjunction conductive layer 12, a first light absorbing layer 31 disposed on the interjunction conductive layer 12, and a first electron transport layer 22 and a second electrode 13 stacked with the first light absorbing layer 31.

[0063] In this embodiment, the solar cell is a tandem solar cell comprising a top solar sub-cell and a bottom solar sub-cell. Sunlight is incident on the top solar sub-cell. The top solar sub-cell has a wide-bandgap second light-absorbing layer 32, while the bottom solar sub-cell has a narrow-bandgap first light-absorbing layer 31. This differentiated bandgap combination improves photon utilization and photoelectric conversion efficiency. A tandem solar cell can have not only two sub-cells, but also more than two sub-cells.

[0064] At the same time, the bottom solar cell with at least a first light absorption layer having a narrow band gap does not need to be provided with a hole transport layer, thereby optimizing the preparation process. On the one hand, it can simplify the structure of solar cell devices and reduce manufacturing time and manufacturing costs. On the other hand, in the preparation process of the stacked solar cell, the top sub-cell is prepared first, and then the bottom sub-cell is prepared; the preparation of the hole transport layer of the bottom solar sub-cell is omitted, and there is no long high-temperature annealing step in the preparation process of the hole transport layer, thereby effectively reducing the performance degradation of the top solar sub-cell caused by high temperature, which is beneficial to improving the stability of the top solar sub-cell, thereby improving the stability of the overall solar cell. However, in the existing stacked solar cells, because both sub-cells prepare the hole transport layer, they undergo two long high-temperature annealing processes in the preparation of the hole transport layer. From the perspective of long-term use, the stability is poor and the conversion efficiency decreases quickly.

[0065] In one embodiment, the tandem solar cell 200 further includes a hole blocking layer disposed between the first electron transport layer 22 and the second electrode 13. The hole blocking layer comprises one or more materials selected from the group consisting of 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline, tin dioxide, zinc oxide, and cerium oxide, and may be BCP and SnO2. The thickness of the hole blocking layer is 5 nm to 15 nm, and may be 7 nm. The hole blocking layer has a low valence band energy level, effectively preventing hole injection. This reduces energy and charge losses caused by interfacial charge recombination, thereby improving the device's energy conversion efficiency.

[0066] In one embodiment, the tandem solar cell 200 further includes a substrate layer (not shown). The substrate layer is a transparent substrate layer. The substrate layer is made of glass and / or a polymer; the polymer includes, but is not limited to, one or more of polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), and polydimethylsiloxane (PDMS).

[0067] In some embodiments, the material of the first electrode 11 is a transparent conductive oxide material, including any one of fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), and indium-doped zinc oxide (IZO).

[0068] In some embodiments, the material of the hole transport layer 21 includes one or more of metal oxide materials, polymer materials, organic small molecule self-assembled molecular materials and their derivatives and materials obtained by doping or passivation thereof. For example, but not limited to metal oxide materials, such as nickel oxide (NiO x2 , 1.5≥x2≥1), molybdenum oxide (MoO x3 , 3≥x3≥2.5), tungsten oxide (WO x4 , 3≥x4≥2.5); polymer materials, such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS); organic small molecule self-assembled molecular materials, such as carbazole or triphenylamine materials containing phosphoric acid or carboxylic acid groups, etc.

[0069] In some embodiments, the material of the electron transport layer (the first electron transport layer 22 and the second electron transport layer 23) is at least one of the following materials and their derivatives and materials obtained by doping or passivation, and the electron transport material includes but is not limited to at least one of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, semiconductor material oxides, titanates, and fluorides. Imides include at least one of perylene imide and its derivatives, naphthalene imide and its derivatives, phthalimide, succinimide, N-bromosuccinimide, glutarimide or maleimide. Quinone compounds include at least one of benzoquinone, naphthoquinone, phenanthrenequinone or anthraquinone. Fullerenes and their derivatives include [6,6]-phenyl C 61 Methyl butyrate (PC 61 BM), [6,6]-phenyl C 71 -Methyl butyrate (PC 71 BM), fullerene C 60 (C 60 ), Fullerene C 70 (C 70 ). The metal element in the metal oxide includes at least one of magnesium (Mg), nickel (Ni), cadmium (Cd), zinc (Zn), indium (In), lead (Pb), molybdenum (Mo), tungsten (W), antimony (Sb), bismuth (Bi), copper (Cu), mercury (Hg), titanium (Ti), silver (Ag), manganese (Mn), iron (Fe), vanadium (V), tin (Sn), zirconium (Zr), strontium (Sr), gallium (Ga), and chromium (Cr). The semiconductor material oxide includes silicon oxide. The titanate includes at least one of strontium titanate and calcium titanate. The fluoride includes at least one of lithium fluoride and calcium fluoride.

[0070] In some embodiments, the electrode material of the second electrode 13 includes one or more of an organic conductive material, an inorganic conductive material, and an organic-inorganic mixed conductive material, including silver (Ag), copper (Cu), carbon (C), gold (Au), aluminum (Al), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), indium-doped zinc oxide (IZO), etc.

[0071] In one embodiment, the first light absorbing layer 31 includes a perovskite material APb y Sn 1-y X3, 0<y<1; A includes organic amine ions and Cs + One or more of; X includes Cl - Br - and I - One or more of .

[0072] Perovskite material APb y Sn1-y In X3, A is any one of an inorganic cation, an organic cation, or an organic-inorganic mixed cation, and can be a methylammonium ion (CH3NH3 + , MA + ), n-butylammonium ion (HC(NH2)2 + , FA + ), cesium ions (Cs + ) at least one; X is any one of an inorganic anion, an organic anion, or an organic-inorganic mixed anion, and may be a chloride ion (Cl - ), bromide ion (Br - ) or iodide ion (I - ) at least one of the following. The perovskite material may also include A2CDX6, wherein C is any one of an inorganic cation, an organic cation, or an organic-inorganic mixed cation, and may be a silver ion (Ag + ); D any one of inorganic cations, organic cations, organic-inorganic mixed cations, which may be bismuth cations (Bi 3+ ), antimony cation (Sb 3+ ), indium cations (In 3+ The thickness of the perovskite layer is 600 nm-1500 nm, and can be 600 nm, 800 nm, 1000 nm, 1200 nm, 1500 nm, etc.

[0073] When perovskite materials are used in the first light absorption layer of solar cells, they have the advantages of high light absorption coefficient, large carrier mobility and adjustable optical band gap. 2+ / Sn 2+ ratio, the band gap of the first light absorbing layer can be adjusted. 2+ The band gap of the first light absorption layer narrows due to the increased proportion of tin and lead. In addition, the first light absorption layer of perovskites containing tin and lead exhibits band bending when the thickness is large. This results in the formation of a band barrier at the interface between the first light absorption layer and the conductive substrate, reducing the probability of electrons flowing from the first light absorption layer to the conductive substrate and reducing non-radiative recombination of carriers.

[0074] In one embodiment, some or all of the tin ions (Sn 2+ ) can be replaced by elements of the same group as tin, such as germanium (Ge).

[0075] According to some embodiments of the present application, the first light absorbing layer contains additives, and the additives include wherein R1 comprises a carbon chain having 1 to 12 carbon atoms; R2 comprises any one of a thiol group, an amino group, and an aryl group; and X comprises any one of an iodide ion, a chloride ion, a bromide ion, a tetrafluoroborate ion, and a thiocyanate ion.

[0076] One end is amino group (-NH2), the other end is carboxyl group (-COOH), it belongs to amino acid molecules, It is an amino acid salt molecule formed by amino acid molecules. Both amino acid molecules and amino acid salt molecules carry -NH3 that can release protons. + Cations and proton-accepting -COO - Anions and halogen anions. Halogen and pseudohalogen anions inhibit the formation of iodine vacancies in the perovskite bulk and interface. Amino groups coordinate with iodide ions to reduce trap states and inhibit iodide migration. Carboxyl groups coordinate with lead and tin ions to inhibit the decomposition of perovskites, effectively passivating surface defects and improving solar cell device stability. This arrangement improves the extraction and transport efficiency of hole carriers, further enhancing the photoelectric conversion efficiency of solar cells without a hole transport layer and suppressing the recombination of electrons and holes.

[0077] Amino acid salt molecules are introduced into the solar cell device based on the structure without hole transport layer. The transparent conductive substrate is anchored to the negatively charged carboxyl end and forms a dipole, forming a built-in electric field. The direction of the electric field points from the perovskite to the substrate interface. The electric field drives the transfer of holes to the substrate interface and repels electrons at the same time, which helps the transfer of electrons from the perovskite surface to the electron transport layer, promotes the charge extraction on the interface, and can effectively make up for the lack of short-circuit current.

[0078] R1 includes a carbon chain with 1-12 carbon atoms, which can adjust the solubility of the additive to match the perovskite host in the first light absorbing layer.

[0079] R2 includes any one of a thiol group, an amino group, and an aryl group. Among them, the thiol group (-SH) and the amino group (-NH2) can provide active hydrogen to interact with the strong electronegative groups of the adjacent carrier transport layer, which can induce the orderly stacking of the interface of the adjacent carrier transport layer, thereby improving the carrier transport performance and improving the performance of the solar cell device. The aryl group can be a phenyl group, or a phenyl group with a functional group, that is, the phenyl group can have a substituent, including but not limited to a hydroxyl group, a carbonyl group, an aldehyde group, etc. The aryl group can be enriched at the interface of the first light absorption layer, blocking the migration of anions in the first light absorption layer, and improving the stability of the solar cell; at the same time, the stacking of organic condensed ring molecules in the adjacent carrier transport layer can be induced by π-π interaction, making their arrangement more orderly, thereby improving the carrier transport performance and improving the performance of the solar cell device.

[0080] X includes iodide ions (I - ), chloride ion (Br - ), bromide ion (Cl - ), tetrafluoroborate ion (BF4 - ), thiocyanate ion (SCN - ) can inhibit the formation of perovskite bulk phase and interface iodine vacancies. The amino group can coordinate with iodide ions to reduce trap states and inhibit the migration of iodide ions, thereby reducing non-radiative recombination losses of electrons at the interface and internally, achieving a passivation effect and significantly improving the open-circuit voltage of the solar cell.

[0081] In one embodiment, the additive includes one or more of 5-aminovaleric acid hydrobromide, 2-aminoethyl acid hydrobromide, 7-aminoheptyl acid hydrobromide, 12-aminododecanoic acid hydrobromide, 5-aminovaleric acid hydroiodide, 5-aminolevulinic acid hydrochloride, 5-aminovaleric acid hydrogen hydrochloride, 5-amino-5-phenylpentane hydrochloride, and 5-aminovaleric acid.

[0082] The above additives can promote hole extraction and passivate defects in the first light absorption layer, thereby simplifying the solar cell device structure while taking into account the performance of the solar cell, which is beneficial to improving the short-circuit current and open-circuit voltage and improving the photoelectric conversion efficiency.

[0083] In one embodiment, the perovskite material APb y Sn 1-y The total molar amount of Pb and Sn in X3 is less than or equal to 5% of the total molar amount of the additive. For example, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, etc., or a range consisting of any two of the above values, such as 0.5%-1%, 2%-4%, 3%-5%, etc. The doping ratio of the additive within this range can both promote hole extraction and passivate defects in the first light absorption layer, while also reducing the impact of the additive on the conductivity of the first light absorption layer.

[0084] The present application also provides a method for preparing a solar cell, comprising: providing a conductive base layer; disposing a light absorption layer precursor liquid on the conductive base layer to form a first light absorption layer, wherein the band gap width of the first light absorption layer is 0.90 eV-1.60 eV; and disposing a first electron transport layer on the first light absorption layer.

[0085] The conductive base layer can be a first electrode or an interjunction conductive layer. In one embodiment, referring to FIG1 , the conductive base layer of a single-junction solar cell 100 is a first electrode 11. In another embodiment, referring to FIG2 , the conductive base layer of a tandem solar cell 200 is an interjunction conductive layer 12.

[0086] The solar cell prepared by the above method does not have a hole transport layer between the conductive base layer and the first light absorption layer, thereby simplifying the device structure and preparation process of the solar cell, and reducing the time and cost of solar cell preparation. At the same time, the obtained solar cell also has a high photoelectric conversion efficiency.

[0087] When the solar cell is a stacked structure, since there is no preparation step for the hole transport layer, the impact of high temperature on the performance of the top sub-cell is reduced, the efficiency loss of the top sub-cell is reduced, and the stability and photoelectric conversion efficiency of the solar cell are improved.

[0088] In one embodiment, the light absorbing layer precursor solution further comprises an additive, the additive comprising At least one of the following, wherein R1 comprises a carbon chain having 1-12 carbon atoms; R2 comprises any one of a thiol group, an amino group, and an aryl group; and X comprises any one of an iodide ion, a chloride ion, a bromide ion, a tetrafluoroborate ion, and a thiocyanate ion. These additives can promote hole extraction and passivate defects in the first light-absorbing layer. Thus, while simplifying the solar cell device structure, they can also maintain solar cell performance, improving short-circuit current and open-circuit voltage, and enhancing photoelectric conversion efficiency.

[0089] In one embodiment, the first light absorbing layer includes a perovskite material, the light absorbing layer precursor includes a mixed solution of formamidine iodine, methylamine iodine, lead iodide, stannous iodide, and stannous fluoride, and the solvent of the mixed solution includes N,N-dimethylformamide and dimethyl sulfoxide.

[0090] When the first light absorbing layer includes a perovskite material, the light absorbing layer precursor solution is prepared by dissolving the perovskite component in an organic solvent. The perovskite component includes formamidinium iodide, methylamine iodide, lead iodide, stannous iodide, and stannous fluoride, which are mixed in a specific molar ratio, such as 0.7:0.3:0.4:0.6:0.05; and N,N-dimethylformamide and dimethyl sulfoxide are mixed in a specific volume ratio, such as 2:1 or 3:1.

[0091] Among light-absorbing materials, perovskite materials have the advantages of low cost and high photoelectric conversion efficiency. In addition, perovskite materials can achieve band gap regulation by adjusting the components to meet different application requirements.

[0092] In one embodiment, the step of disposing the light absorbing layer precursor liquid on the conductive base layer includes: providing the light absorbing layer precursor liquid, and spin-coating the light absorbing layer precursor liquid on the conductive base layer to form a first light absorbing layer.

[0093] The light-absorbing layer precursor solution includes a perovskite precursor solution. The above-mentioned preparation method is a one-step solution method. This method involves dissolving the entire perovskite precursor in a solvent to obtain the perovskite precursor solution, then directly spin-coating the perovskite precursor solution to form the perovskite film in one step. The overall process is simple. The first light-absorbing layer can also be prepared using a two-step solution method and vapor deposition.

[0094] In one embodiment, the step of spin-coating a light absorbing layer precursor liquid on a conductive base layer to form a first light absorbing layer includes: spin coating in two steps, the first step having a spin coating speed of 2000-6000 revolutions per minute and a spin coating time of 5-20 seconds; the second step having a spin coating speed of 3000-6000 revolutions per minute and a spin coating time of 30-90 seconds.

[0095] In the process before the second step spin coating ends (for example, after the first step spin coating ends), an anti-solvent can be added dropwise. Anti-solvent refers to a poor solvent for light absorbing materials (for example, perovskite materials), including chlorobenzene, toluene, anisole, ethyl acetate, etc. In the spin coating process of the perovskite precursor solution, a certain amount of anti-solvent is evenly added dropwise, and excessive solvent is rapidly volatilized after being extracted by the anti-solvent. The supersaturation of the precursor in the wet film increases rapidly, promoting the rapid nucleation of the mesophase. In the subsequent mesophase thin film annealing process, the slow volatilization of the complexing solvent also delays crystallization rate, and the crystal growth kinetics process of rapid nucleation and slow crystallization can be achieved. Except utilizing anti-solvent, the solvent in the perovskite precursor solution can also be extracted out quickly by vacuum flash evaporation.

[0096] The first step of spin coating has a low speed, which is conducive to making the perovskite precursor solution evenly disposed on the conductive base layer; the second step of spin coating is conducive to the rapid extraction of the solvent in the perovskite precursor solution and the promotion of the nucleation and growth of perovskite seed crystals.

[0097] In one embodiment, the step of disposing the light absorbing layer precursor liquid on the conductive base layer further comprises: disposing the light absorbing layer precursor liquid on the conductive base layer and forming a first light absorbing layer after heat treatment.

[0098] The heat treatment process involves placing the coated first light-absorbing layer film in a high-temperature furnace or hot plate for heat treatment (also known as annealing), typically at temperatures between 100°C and 500°C. Heat treatment promotes the growth of crystals in the first light-absorbing layer, modulates crystal morphology, helps reduce defects, and improves photoelectric conversion efficiency. It also helps completely remove residual organic matter and solvents, improving the purity of the film.

[0099] According to some embodiments of the present application, the present application also provides a photovoltaic power generation system, which includes any of the above-mentioned solar cells.

[0100] Photovoltaic power generation system refers to a power generation system that uses the photovoltaic effect to directly convert solar radiation energy into electrical energy. It is divided into a stand-alone photovoltaic power generation system (Stand-alone PV System) and a grid-connected photovoltaic power generation system (Grid-connected PV System). The stand-alone photovoltaic power generation system consists of a solar photovoltaic array composed of photovoltaic modules, a battery pack, a charge controller, a power electronic converter (inverter), and a load. The grid-connected photovoltaic power generation system consists of a photovoltaic array, a high-frequency DC / DC boost circuit, a power electronic converter (inverter), and a system monitoring system.

[0101] The photovoltaic power generation system includes a plurality of electrically connected photovoltaic modules, where a plurality refers to an integer number of two or more.

[0102] According to some embodiments of the present application, the present application further provides an electrical device, which includes the solar cell provided by the above solution, and the solar cell is used to provide electrical energy to the electrical device.

[0103] The electrical equipment includes common equipment that includes the solar cells of the present application, such as those used in the fields of communications, transportation, industry, agriculture, and lighting. Examples of electrical equipment include satellites, communications equipment, traffic lights, lighthouses, wireless phone booths, drilling monitoring equipment, power systems, camping lanterns, electric vehicles, and electronic device chargers.

[0104] The electrical equipment can be powered solely by solar cells, or by a combination of solar cells and energy storage batteries, i.e., the electrical equipment is equipped with both solar cells and energy storage batteries. Energy storage batteries are not limited to primary batteries or secondary batteries, and include, but are not limited to, lithium-ion secondary batteries and sodium-ion secondary batteries.

[0105] The beneficial effects of the present application are further illustrated below with reference to the examples.

[0106] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0107] 1. Solar cell device production

[0108] Example 1:

[0109] (1) Cleaning a transparent conductive glass with indium tin oxide (ITO) strips etched on its surface with deionized water, glass cleaner, deionized water, acetone, and anhydrous ethanol in sequence, then immersing the cleaned indium tin oxide transparent conductive film substrate in a beaker of anhydrous ethanol and sealing it with tin foil for storage;

[0110] (2) Cesium iodide, formamidine iodine, methylamine iodine, lead iodide, stannous iodide, and stannous fluoride are mixed in a molar ratio of 0.1:0.6:0.3:0.5:0.5:0.05 to obtain a perovskite precursor, and an additive 5-aminovaleric acid hydrobromide is added to the perovskite precursor. Based on the total molar amount of Pb and Sn in the perovskite precursor, the molar amount of the additive accounts for 1%, and the mixture is dissolved in a solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) with a volume ratio of 2:1;

[0111] (3) drying the indium tin oxide transparent conductive film substrate with nitrogen and performing a UV ozone cleaning treatment for 15 minutes;

[0112] (4) Place the cleaned transparent conductive glass substrate in a nitrogen glove box; use a pipette to absorb 100 μL of the filtered perovskite precursor solution and evenly drop it onto the transparent conductive glass substrate; use a two-step spin coating method to prepare the perovskite wet film: the first step is to spin at a speed of 2000 rpm and a spin coating time of 10 seconds; the second step is to spin at a speed of 5000 rpm and a spin coating time of 50 seconds, and 400 μL of chlorobenzene is added 20 seconds before the end of the spin coating. After the spin coating is completed, the film is placed on a hot plate at a temperature of 100 degrees Celsius for 10 minutes of annealing treatment to complete the preparation process of the perovskite film and obtain Cs 0.1 FA 0.6 MA 0.3 Pb 0.5 Sn 0.5 The I3 perovskite layer has a thickness of 800 nm. All the above processes were completed in a nitrogen glove box.

[0113] (5) Fullerene (electron transport layer), 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (hole blocking layer) and copper (metal electrode) were deposited by vacuum evaporation with thicknesses of 25 nm, 6 nm and 100 nm, respectively, to complete the preparation of solar cell 1.

[0114] Example 2:

[0115] (1) First electrode: The transparent conductive glass with indium tin oxide (ITO) strips etched on the surface was cleaned with deionized water, glass cleaner, deionized water, acetone, and anhydrous ethanol in sequence, and dried before use in the next step.

[0116] (2) Hole transport layer: 0.3 mg of [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphoric acid (MeO-4PACz) was added to 1 mL of ethanol and stirred. The ethanol solution of MeO-4PACz was spin-coated onto the substrate cleaned in step (1) at a spin-coating speed of 1000 rpm for 30 s. The substrate was then transferred to a hot plate and annealed at 100°C for 15 min to obtain a hole transport layer.

[0117] (3) Second light absorption layer: 123 mg FAI, 59 mg FABr, 46 mg CsI, 25 mg CsBr, 428 mg PbI2, and 209 mg PbBr2 were added to 1 mL DMF:DMSO = 3:1 (volume ratio) solvent, stirred at 700 rpm on a magnetic stirrer for 12 h, and filtered to obtain a perovskite precursor solution; 100 μL of the prepared perovskite precursor solution was added dropwise to the hole transport layer prepared in step (2) at a speed of 1000 rpm for 10 s, and then spin-coated for 40 s at an acceleration of 1000 rpm / s and a speed of 5000 rpm. 400 μL of ethyl acetate was added after about 30 s, and finally the spin-coated perovskite was annealed on a hot plate at 100 ° C for 10 min to obtain FA 0.8 Cs 0.2 Pb(I 0.65 Br 0.35 )3 perovskite layer with a thickness of 350nm.

[0118] (4) Second electron transport layer: a 10 nm layer of C was evaporated on the wide bandgap second light absorbing layer prepared in step (3). 60 , as an electron transport layer.

[0119] (5) Interjunction conductive layer: Use atomic layer deposition equipment to deposit the C prepared in step (4) 60 A 20nm SnO layer is prepared on the film layer x (1.5≤x≤2); in the prepared SnO x A 0.5 nm Au layer is prepared on the (1.5≤x≤2) substrate.

[0120] (6) First light absorbing layer: The first light absorbing layer is prepared on the substrate on which the interlayer conductive layer has been prepared in step (5), and cesium iodide, formamidine iodine, methylamine iodine, lead iodide, stannous iodide, and stannous fluoride are mixed in a molar ratio of 0.1:0.6:0.3:0.5:0.5:0.05 to obtain a perovskite precursor, and an additive 5-aminovaleric acid hydrobromide is added to the perovskite precursor. Based on the total molar amount of Pb and Sn in the perovskite precursor, the molar amount of the additive accounts for 1%. Dissolve in a 2:1 volume ratio of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solvent; use a pipette to draw 100 microliters of the filtered perovskite precursor solution and evenly drop it onto a transparent conductive glass substrate; use a two-step spin coating method to prepare a perovskite wet film: the first step is to spin at a speed of 2000 rpm and a spin coating time of 10 seconds; the second step is to spin at a speed of 5000 rpm and a spin coating time of 50 seconds, and 400 microliters of chlorobenzene is added 20 seconds before the end. After the spin coating is completed, the film is placed on a hot plate at a temperature of 100 degrees Celsius for 10 minutes of annealing to complete the preparation process of the perovskite film and obtain Cs 0.1 FA 0.6 MA 0.3 Pb 0.5 Sn 0.5 The I3 perovskite layer has a thickness of 800nm, and the above processes are all completed in a nitrogen glove box;.

[0121] (7) First electron transport layer: Use evaporation equipment to evaporate 25nm of C on the substrate where the first light absorption layer has been prepared in step (6). 60 .

[0122] (8) Second electrode: A 100 nm thick Cu electrode was evaporated on the first electron transport layer in step (7) to obtain a solar cell 2.

[0123] Example 3-Example 10:

[0124] On the basis of Example 1, the type of additive in step (2) was changed. Examples 3-10 respectively used 2-aminoethyl acid hydrobromide, 7-aminoheptyl acid hydrobromide, 12-aminododecanoic acid hydrobromide, 5-aminopentanoic acid hydroiodide, 5-aminopentanoic acid hydrogen hydrochloride, 5-aminolevulinic acid hydrochloride, 5-amino-5-phenylpentane hydrochloride, and 5-aminopentanoic acid. The other steps remained unchanged to obtain solar cells 3-10.

[0125] Example 11-Example 12:

[0126] On the basis of Example 1, the amount of additive added in step (2) was changed from 1% to 3% and 5% in Example 11 and Example 12 respectively, while other steps remained unchanged, to obtain solar cells 11 and 12.

[0127] Example 13:

[0128] Based on Example 1, the additive in step (2) was removed. After step (1), a 1.5 mg / mL 5-aminovaleric acid hydrobromide solution (using ethanol as the solvent) was spin-coated (1000 rpm, 30 seconds) onto the indium tin oxide transparent conductive film substrate and heated on a hot plate at 100° C. for 10 minutes. Steps (2) to (5) were moved to the end of the aforementioned steps, yielding solar cell 13.

[0129] Example 14: Based on Example 2, the additive in step (6) is removed, and other parameters and steps remain unchanged.

[0130] Comparative Example 1:

[0131] 1) Cleaning a transparent conductive glass having indium tin oxide (ITO) strips etched on its surface with deionized water, glass cleaner, deionized water, acetone, and anhydrous ethanol in sequence, then immersing the cleaned indium tin oxide transparent conductive film substrate in a beaker of anhydrous ethanol and sealing it with tin foil for storage;

[0132] (2) Cesium iodide, formamidine iodine, methylamine iodine, lead iodide, stannous iodide, and stannous fluoride were mixed in a molar ratio of 0.1:0.6:0.3:0.5:0.5:0.05 to obtain a perovskite precursor, and the mixture was dissolved in a solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 2:1;

[0133] (3) drying the indium tin oxide transparent conductive film substrate with nitrogen and performing a UV ozone cleaning treatment for 15 minutes;

[0134] (4) Use a pipette to draw 100 μL of PEDOT:PSS solution and evenly drop it onto the cleaned transparent conductive glass substrate at a speed of 3000 rpm for 30 seconds. After the spin coating is completed, place it on a hot plate at 150°C for annealing for 30 minutes to prepare a hole transport layer;

[0135] (5) Place the indium tin oxide transparent conductive film substrate prepared in step 4 into a nitrogen glove box; use a pipette to absorb 100 microliters of the filtered perovskite precursor solution and evenly drop it onto the transparent conductive glass substrate; use a two-step spin coating method to prepare the perovskite wet film: the first step is to spin-coat at a speed of 2000 rpm and a spin-coating time of 10 seconds; the second step is to spin-coat at a speed of 5000 rpm and a spin-coating time of 50 seconds, and 400 microliters of chlorobenzene are added 20 seconds before the end of the spin coating. After the spin coating is completed, the film is placed on a hot plate at a temperature of 100 degrees Celsius for 10 minutes of annealing treatment to complete the preparation process of the perovskite film and obtain Cs 0.1 FA 0.6 MA 0.3 Pb 0.5 Sn 0.5 The I3 perovskite layer has a thickness of 800 nm. All the above processes were completed in a nitrogen glove box.

[0136] (6) The electron transport layer fullerene, the hole blocking layer 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline and the metal electrode copper were evaporated to thicknesses of 25 nm, 6 nm and 100 nm respectively by vacuum evaporation to complete the preparation of solar cell 3.

[0137] Comparative Example 2: Compared with Example 14, a hole transport layer was also made on the bottom sub-cell. The specific preparation method was the same as that of Comparative Example 1, and other parameters and steps remained unchanged.

[0138] Comparative Example 3: Compared with Example 2, a hole transport layer was also made on the bottom sub-cell. The specific preparation method was the same as that of Comparative Example 1, and other parameters and steps remained unchanged.

[0139] 2. Solar cell device performance test

[0140] (1) Bandgap testing of perovskite materials

[0141] Test samples: The preparation method of Example 1 was used to prepare the entire perovskite cell sample; the preparation method of Example 2 was used to prepare the entire perovskite cell sample.

[0142] Test method: UV-Vis Diffuse Reflectance (UV-Vis DRS) - Use an integrating sphere to test UV-Vis Diffuse Reflectance, use a background test blank sample, test the background baseline, and after the baseline correction is completed, place the sample in the sample card slot for testing to obtain the UV-Vis Diffuse Reflectance spectrum.

[0143] Data processing:

[0144] Formula: Eg (eV) = hc / λg = 1240 / λg (nm)

[0145] Eg is the bandgap; λg is the band edge wavelength of the semiconductor. The λg value in the UV-Vis DRS spectrum is obtained by data processing, and the Eg value is calculated.

[0146] Test results:

[0147] In Example 1, the band gap of the perovskite material is 1.23-1.26 eV;

[0148] In Example 2, the band gap of the perovskite material in the first light absorbing layer is 1.23-1.26 eV; the band gap of the perovskite material in the second light absorbing layer is 1.75-1.79 eV.

[0149] (2) IV measurement method:

[0150] By changing the bias voltage point and measuring the current at the same time, the IV characteristics of the sample under test can be obtained.

[0151] a) Place the test fixture containing the sample cell on the sample holder so that it is located in the measurement plane and ensure that the sample cell is located at the center of the solar simulator's output light spot (or the normal line of the photovoltaic cell is parallel to the center line of the solar simulator's light beam);

[0152] b) Using Guangyan's solar simulator, which complies with the national standard IEC61215 for testing, and using crystalline silicon solar cells to calibrate the light intensity to reach the intensity of one sun, at 1000W / m 2 Under the condition of irradiance, a mask is installed on the sample battery to be tested, and the temperature of the sample battery is controlled by a temperature monitoring device so that the temperature of the sample is maintained at (30±5℃) during the measurement process;

[0153] c) Set the scanning direction, voltage range, scanning interval voltage and scanning interval time. It is recommended that the scanning interval should not be greater than 0.02V and the interval between two adjacent points should not be less than 0.3s. Measure the forward and reverse current-voltage characteristics of the sample battery under test and record the open circuit voltage V OC , short-circuit current J SC .

[0154] Calculation formula: Fill factor FF = J m *V m / V OC *J SC , energy conversion efficiency PCE=V OC *J SC *FF / P in .P in is the incident light intensity, which is equal to 10 3 W / m 2 .

[0155] The test results are shown in Table 1.

[0156] Table 1 Test parameters of various embodiments and comparative examples

[0157] Note: There is no hole transport layer in Examples 1 and 3-12; the bottom sub-cell in Example 2 has no hole transport layer, while the top sub-cell has a hole transport layer; in Example 13, 5-aminovaleric acid hydrobromide is not doped in the perovskite material, but is layered separately.

[0158] 3. Analysis of solar cell device performance test results

[0159] Please refer to Table 1.

[0160] Example 1 and Examples 3-13 are single-junction solar cells, and the energy conversion efficiency of the resulting solar cell devices is relatively high, basically above 21%. This shows that even in the absence of a hole transport layer, the single-junction solar cell devices in the embodiments herein can achieve a relatively high photoelectric conversion efficiency, and there is no substantial reduction in efficiency relative to the device with a hole transport layer (Comparative Example 1). Moreover, the additives can be directly doped in the perovskite layer or layered separately, both of which can have a relatively high conversion efficiency. Therefore, the solar cell structure provided in this application can provide a relatively high photoelectric conversion efficiency while simplifying the device structure and preparation process.

[0161] Furthermore, in Example 1, Examples 3-9 and Examples 11-12, the additives used are amino acid salt molecules. In Examples 1 and 3-5, the carbon chain R1 lengths of the additives varied; in Examples 1 and 6-7, the salt-forming anions X of the additives varied; and in Examples 1 and 8-9, the side chain functional groups R2 of the additives varied. Test results indicate that all of these additives can improve the energy conversion efficiency of battery devices.

[0162] In Example 10, the additive 5-aminovaleric acid belongs to the amino acid molecule It can also improve the energy conversion efficiency of battery devices.

[0163] In Example 1 and Examples 11-12, the amount of additives added is different, indicating that based on the total molar amount of Pb and Sn in the perovskite material, when the amount of additives added (molar ratio) is less than or equal to 5%, the energy conversion efficiency of the solar cell device can be improved.

[0164] Examples 2 and 14 are stacked solar cells, and the energy conversion efficiency of the solar cell devices is also relatively high; this shows that even in the absence of a hole transport layer, the devices in the embodiments of this article can also have a relatively high conversion efficiency; at the same time, the additives also have a relatively obvious improvement on the stacked solar cell devices.

[0165] Compared with Comparative Examples 2 and 3, Examples 2 and 14 have a design without a hole transport layer, and although the conversion efficiency is reduced to a certain extent, the reduction is small. Furthermore, from the perspective of long-term effects, because there is no hole transport layer in Examples 2 and 14, not only the preparation process is optimized, the solar cell device structure is simplified, and the manufacturing time and cost are reduced. On the other hand, in the preparation process of the stacked solar cell, the top sub-cell is prepared first, and then the bottom sub-cell is prepared. The preparation of the hole transport layer of the bottom solar sub-cell is omitted, and there is no long-term high-temperature annealing step in the preparation process of the hole transport layer. Therefore, the performance degradation of the top solar sub-cell caused by high temperature is effectively reduced, which is beneficial to improving the stability of the top solar sub-cell, thereby improving the stability of the overall solar cell. In other words, from the perspective of long-term device stability and efficiency, the effects of Examples 2 and 14 are better than those of Comparative Examples 2 and 3.

[0166] In summary, the solar cell structure provided in the present application simplifies the device structure and preparation process while providing higher photoelectric conversion efficiency.

[0167] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A solar cell, wherein: The solar cell includes a conductive base layer, a first light absorbing layer disposed on the conductive base layer, and a first electron transport layer stacked with the first light absorbing layer; The band gap width of the first light absorbing layer is 0.90 eV-1.60 eV.

2. The solar cell according to claim 1, wherein The conductive base layer is a first electrode, and the solar cell includes the first electrode, the first light absorbing layer disposed on the first electrode, and a first electron transport layer and a second electrode stacked with the first light absorbing layer.

3. The solar cell according to claim 1, wherein The conductive base layer is an interjunction conductive layer, and the solar cell further includes a second light absorbing layer arranged on a side of the interjunction conductive layer away from the first light absorbing layer.

4. The solar cell according to claim 3, wherein The band gap width of the second light absorbing layer is 1.60 eV-2.50 eV.

5. The solar cell according to claim 3 or 4, wherein The solar cell further includes a second electron transport layer disposed between the interjunction conductive layer and the second light absorbing layer; and a hole transport layer disposed on a side of the second light absorbing layer away from the second electron transport layer.

6. The solar cell according to claim 5, wherein The solar cell includes a first electrode, the hole transport layer, the second light absorption layer, the second electron transport layer, the interjunction conductive layer stacked with the first electrode, the first light absorption layer arranged on the interjunction conductive layer, and a first electron transport layer and a second electrode stacked with the first light absorption layer.

7. The solar cell according to any one of claims 1 to 6, wherein: The first light absorbing layer contains additives, and the additives include at least one of: R1 includes a carbon chain having 1 to 12 carbon atoms; R2 includes any one of thiol, amino, and aryl; X includes any one of iodide ion, chloride ion, bromide ion, tetrafluoroborate ion, and thiocyanate ion.

8. The solar cell according to claim 7, wherein The additives include one or more of 5-aminovaleric acid hydrobromide, 2-aminoethyl acid hydrobromide, 7-aminoheptyl acid hydrobromide, 12-aminododecanoic acid hydrobromide, 5-aminovaleric acid hydroiodide, 5-aminolevulinic acid hydrochloride, 5-aminovaleric acid hydrogen hydrochloride, 5-amino-5-phenylvaleric acid hydrochloride, and 5-aminovaleric acid.

9. The solar cell according to any one of claims 1 to 8, wherein: The first light absorbing layer comprises a perovskite material APbySn1-yX3, 0<y<1; A includes one or more of organic amine ions and Cs+; X includes one or more of Cl-, Br- and I-.

10. The solar cell according to any one of claims 7 to 9, wherein: Based on the total molar amount of Pb and Sn in the perovskite material APbySn1-yX3, the molar amount of the additive is less than or equal to 5%.

11. The solar cell according to claim 2 or 6, wherein The solar cell further includes a hole blocking layer disposed between the first electron transport layer and the second electrode; The hole blocking layer includes materials such as 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline, One or more of tin, zinc oxide, and cerium oxide.

12. The solar cell according to claim 11, wherein The thickness of the hole blocking layer is 5nm-15nm.

13. A method for preparing a solar cell, wherein: include: Providing a conductive base layer; Disposing a light absorbing layer precursor liquid on the conductive base layer to form a first light absorbing layer, wherein the band gap width of the first light absorbing layer is 0.90 eV-1.60 eV; A first electron transport layer is disposed on the first light absorbing layer.

14. The method for preparing a solar cell according to claim 13, wherein: The light absorbing layer precursor solution further comprises an additive, wherein the additive comprises at least one of and , wherein, R1 includes a carbon chain having 1 to 12 carbon atoms; R2 includes any one of thiol, amino, and aryl; X includes any one of iodide ion, chloride ion, bromide ion, tetrafluoroborate ion, and thiocyanate ion.

15. The method for preparing a solar cell according to claim 13 or 14, wherein: The first light absorbing layer includes a perovskite material, and the light absorbing layer precursor solution includes: A mixed solution of formamidine iodine, methylamine iodine, lead iodide, stannous iodide and stannous fluoride, wherein the solvent of the mixed solution comprises N,N-dimethylformamide and dimethyl sulfoxide.

16. The method for preparing a solar cell according to any one of claims 13 to 15, wherein: The step of placing the light absorbing layer precursor liquid on the conductive base layer comprises: A light absorbing layer precursor solution is provided, and the light absorbing layer precursor solution is spin-coated on the conductive base layer to form the first light absorbing layer.

17. The method for preparing a solar cell according to claim 16, wherein: The step of spin coating the light absorbing layer precursor solution on the conductive base layer to form the first light absorbing layer comprises: The spin coating is carried out in two steps. The first step is at a spin coating speed of 2000-6000 rpm and a spin coating time of 5-20 seconds. The second step is at a spin coating speed of 3000-6000 rpm and a spin coating time of 30-90 seconds.

18. A photovoltaic power generation system, wherein: A solar cell comprising the solar cell according to any one of claims 1 to 12, or a solar cell prepared by the method for preparing a solar cell according to any one of claims 13 to 17.

19. An electrical device, wherein: A solar cell comprising the solar cell according to any one of claims 1 to 12, or a solar cell prepared by the method for preparing a solar cell according to any one of claims 13 to 17.

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