Solar cell and preparation method thereof, hole transport layer, power utilization device and power generation device

Abstract

The invention relates to the technical field of solar cells, in particular to a solar cell and a preparation method thereof, a hole transport layer, a power utilization device and a power generation device. The solar cell comprises a first electrode, a hole transport layer, a light absorption layer and a second electrode which are arranged in sequence. One side, facing the light absorption layer, of the hole transport layer is provided with a plurality of concave surfaces. The side, facing the light absorption layer, of the hole transport layer is provided with a plurality of concave surfaces, the concave surfaces increase the surface area between the hole transport layer and the light absorption layer, a larger contact interface is formed between the light absorption layer and the hole transport layer, the photoelectric response area of light and the light absorption layer is increased, meanwhile, the increase of the surface area is beneficial to prolonging the propagation path of the light in the device, and the photoelectric response efficiency is improved. Therefore, the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a solar cell and its preparation method, hole transport layer, power supply device, and power generation device. Background Technology

[0002] A solar cell is a device that directly converts light energy into electrical energy through the photoelectric effect or photochemical effect.

[0003] The absorption of light energy by solar cells affects their performance, and there is a problem of light loss during the process of light entering solar cells. Summary of the Invention

[0004] The main objective of this invention is to provide a solar cell that improves the photoelectric conversion efficiency of solar cells.

[0005] To achieve the above objectives, the present invention proposes a solar cell, which includes a first electrode, a hole transport layer, a light-absorbing layer, and a second electrode arranged sequentially.

[0006] The hole transport layer has multiple concave surfaces on the side facing the light-absorbing layer.

[0007] The hole transport layer has multiple concave surfaces on the side facing the light-absorbing layer. These concave surfaces increase the surface area between the hole transport layer and the light-absorbing layer, resulting in a larger contact interface between them. This increases the photoelectric response area of ​​the light and the light-absorbing layer. At the same time, the increased surface area helps to extend the propagation path of light in the light-absorbing layer, improving light utilization and thus enhancing the photoelectric conversion efficiency of the solar cell.

[0008] Optionally, the shapes of the plurality of concave surfaces include spherical concave surfaces or near-spherical concave surfaces;

[0009] And / or, the plurality of said concave surfaces are distributed in an array.

[0010] In one embodiment, the shapes of the plurality of concave surfaces include spherical concave surfaces or near-spherical concave surfaces. The spherical concave surfaces or near-spherical concave surfaces have a light-focusing effect and can improve the incident efficiency of light.

[0011] In one embodiment, the multiple concave surfaces are arranged in an array, indicating that the multiple concave surfaces are arranged in an orderly manner, and the orderly structure can increase the surface area.

[0012] Optionally, the structure formed by the plurality of concave surfaces includes an array of hemispherical shells.

[0013] In one embodiment, the structure composed of multiple concave surfaces includes a hemispherical shell array. The hole transport layer structure can be considered to include this hemispherical shell array, which is an inverse opal structure. Inverse opal is a special photonic crystal with a photonic bandgap effect, which improves light transmittance, allowing light to be effectively absorbed by the light-absorbing layer after passing through the hole transport layer. The hemispherical shell array structure of the hole transport layer can provide a larger surface area, resulting in a larger contact interface between the light-absorbing layer and the hole transport layer. This increases the photoelectric response area between the light and the light-absorbing layer, extends the light propagation path in the device, improves light utilization, and thus enhances the photoelectric conversion efficiency of the solar cell.

[0014] It is understandable that the hemispherical shell alignment is a single-layer structure. When using a template to prepare the inverse opal structure, a single layer of template is used to prepare a single layer of hemispherical shell alignment.

[0015] Optionally, the hemispherical shell array has a spherical shell array on the side facing the first electrode.

[0016] It is understandable that the inverse opal structure prepared using a single-layer template consists of a single-layer hemispherical shell array located on the surface of the hole transport layer; the inverse opal structure prepared using a double-layer template consists of a single-layer spherical shell array and a single-layer hemispherical shell array, wherein the hemispherical shell array is located on the surface of the hole transport layer and the spherical shell array is located inside the hole transport layer; and the inverse opal structure prepared using a triple-layer template consists of two spherical shell arrays and a single-layer hemispherical shell array.

[0017] It is understandable that as the number of array layers increases, the photoelectric conversion efficiency will decrease. The more array layers there are, the thicker the hole transport layer will become, and an excessively thick hole transport layer will affect carrier transport.

[0018] Optionally, the radius of the spherical concave surface is from 25 nm to 500 nm.

[0019] In this application, the radius of the spherical concave surface is between 25 nm and 500 nm. The radius meets the above range, which helps the light transmittance.

[0020] Optionally, the thickness of the hole transport layer ranges from 10 nm to 50 nm.

[0021] Optionally, the refractive index of the hole transport layer is less than the refractive index of the light-absorbing layer.

[0022] Optionally, the hole transport layer is made of at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and poly(ethylenedioxythiophene-polystyrene sulfonate).

[0023] Understandably, the thickness of the hole transport layer affects performance. An excessively thick layer can impair hole transport; for example, it affects both the transport and extraction efficiency of holes. An overly thick hole transport layer may slow down hole transport, increase the probability of charge recombination, and lower the open-circuit voltage of the cell. Conversely, an excessively thin layer may not adequately cover the first electrode; for instance, if it's too thin, the light-absorbing layer might directly contact the first electrode, causing leakage current and reducing device efficiency. Therefore, employing the aforementioned thickness of the hole transport layer can improve the photoelectric conversion efficiency of solar cells.

[0024] In this application, the refractive index of the hole transport layer is less than that of the light-absorbing layer. When incident light enters a medium with a low refractive index, its propagation direction will shift towards the normal, and the refraction angle will become smaller. At the interface between the hole transport layer and the light-absorbing layer, the normal is towards the center of the sphere. The closer the light is to the normal during the refraction process, the less likely it is to escape from the side of the solar cell. Therefore, the refractive index of the hole transport layer is less than that of the light-absorbing layer, and more light enters the light-absorbing layer, which helps to improve the photoelectric conversion efficiency of the solar cell.

[0025] In this application, the hole transport layer material includes at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and poly(ethylenedioxythiophene-polystyrene sulfonate).

[0026] Optionally, the refractive index of the hole transport layer ranges from 1.8 to 2.1.

[0027] Optionally, the refractive index of the light-absorbing layer ranges from 2.3 to 2.6.

[0028] In this application, the refractive index of the hole transport layer meets the above-mentioned range, which helps to improve the absorption of light in the light-absorbing layer.

[0029] In this application, the refractive index of the light-absorbing layer meets the above-mentioned range, which helps to improve the absorption of light in the light-absorbing layer.

[0030] Optionally, a first passivation layer is provided between the hole transport layer and the light-absorbing layer;

[0031] And / or, an electron transport layer is provided between the light-absorbing layer and the second electrode.

[0032] In this application, a first passivation layer is provided between the hole transport layer and the light-absorbing layer. It is understood that the passivation layer is used to passivate surface / interface defects of the hole transport layer, reduce charge carrier recombination, and thus improve the photoelectric conversion efficiency of the battery. In particular, the hole transport layer of the inverse opal structure of this application has an uneven thickness, especially in the structure of a single-layer hemispherical array. In the thinnest region, the light-absorbing layer may directly contact the first electrode, generating leakage current. To reduce this risk, a first passivation layer is provided between the light-absorbing layer and the hole transport layer.

[0033] In this application, an electron transport layer is provided between the light-absorbing layer and the second electrode.

[0034] Optionally, the refractive index of the hole transport layer is less than the refractive index of the first passivation layer;

[0035] And / or, the thickness of the first passivation layer is less than the maximum depth of the concave surface;

[0036] And / or, a second passivation layer is provided between the light-absorbing layer and the electron transport layer;

[0037] And / or, a barrier layer is provided between the electron transport layer and the second electrode.

[0038] In this application, the refractive index of the hole transport layer is less than that of the first passivation layer. Since the incident light will deviate towards the normal when it enters the medium with a low refractive index, it is not easy for it to exit from the side. In the process of light entering the first passivation layer from the hole transport layer, it helps to increase the probability of light entering the first passivation layer.

[0039] In this application, the thickness of the first passivation layer is less than the maximum depth of the concave surface, so as to avoid the passivation layer from completely covering the concave surface and make the surface of the first passivation layer also concave, which helps to increase the surface area between the first passivation layer and the light-absorbing layer.

[0040] For example, when the concave surface is a spherical concave surface, the thickness of the first passivation layer is less than the radius of the spherical concave surface. In this way, the contact interface between the first passivation layer and the light-absorbing layer is still spherical, which helps the light to be deflected from the first passivation layer into the light-absorbing layer towards the normal and to converge towards the center of the sphere, thereby increasing the probability of the light entering the light-absorbing layer.

[0041] In this application, a second passivation layer is provided between the light-absorbing layer and the electron transport layer to reduce charge carrier recombination.

[0042] This application incorporates a barrier layer between the electron transport layer and the second electrode. This barrier layer has a deep valence band level, effectively blocking majority carriers (holes) from transporting to the second electrode. In other words, the barrier layer typically has a deep valence band level. This design effectively blocks majority carriers (holes) from passing through while allowing minority carriers (electrons) to transport to the second electrode. This selective transport helps reduce recombination of electrons and holes before they reach the second electrode, thereby improving the photoelectric conversion efficiency of the solar cell.

[0043] Furthermore, during the deposition process using physical vapor deposition techniques such as magnetron sputtering, high-energy particles may damage the underlying film layer, causing lattice defects or changes in chemical structure. Barrier layers can act as protective layers to reduce this damage. In other words, barrier layers can improve the crystal quality and interface quality of the electron transport layer, thereby enhancing electron transport efficiency and overall device performance.

[0044] Optionally, the thickness of the first passivation layer ranges from 0.5 nm to 3 nm;

[0045] And / or, the refractive index of the first passivation layer ranges from 1.9 to 2.3;

[0046] And / or, the material of the first passivation layer includes at least one of 3-triethoxysilylpropionitrile, 2-aminothiazolyl-4-acetic acid, and 1-hydroxy-4-carbonylbenzene.

[0047] In this application, the thickness of the first passivation layer ranges from 0.5 nm to 3 nm. It is understood that an excessively thick passivation layer can affect the transport of charge carriers. The thickness of the first passivation layer within the above range can reduce the impact of the passivation layer thickness on the charge carriers.

[0048] In this application, the refractive index of the first passivation layer meeting the above-mentioned range helps to improve the absorption of light in the light-absorbing layer.

[0049] The material of the first passivation layer in this application includes at least one of 3-triethoxysilylpropionitrile, 2-aminothiazolyl-4-acetic acid, and 1-hydroxy-4-carbonylbenzene.

[0050] Optionally, the material of the second passivation layer includes at least one of piperazine, N-methyl-1,3-propanediammonium diiodide, 3-aminopyridine, and ferrocene;

[0051] And / or, the material of the barrier layer includes at least one of indium tungsten oxide, indium tin oxide, copper bath, and zirconium acetylacetonate;

[0052] And / or, the material of the electron transport layer includes at least one of [6,6]-phenyl-C61-butyrate, [6,6]-phenyl-C71-butyrate, fullerene and its derivatives, tin dioxide, and zinc oxide.

[0053] In this application, the material of the second passivation layer includes at least one of piperazine, N-methyl-1,3-propanediammonium diiodide, 3-aminopyridine, and ferrocene; the material of the barrier layer includes at least one of indium tungsten oxide, indium tin oxide, copper bath, and zirconium acetylacetonate; and the material of the electron transport layer includes at least one of methyl [6,6]-phenyl-C61-butyrate, methyl [6,6]-phenyl-C71-butyrate, fullerene and its derivatives, tin dioxide, and zinc oxide.

[0054] Optionally, the light-absorbing layer comprises a crystalline material;

[0055] And / or, the band gap of the light-absorbing layer ranges from 1.20 eV to 2.30 eV;

[0056] And / or, the thickness of the light-absorbing layer ranges from 400 nm to 1000 nm;

[0057] And / or, the material of the first electrode includes at least one of FTO, ITO, AZO, BZO, and IZO;

[0058] And / or, the material of the second electrode includes an inorganic conductive material, which includes at least one of Ag, Cu, graphite, Au, Al, IZO, and ITO.

[0059] In this application, when the light-absorbing layer includes a crystalline material, the hole transport layer serves as the substrate supporting the light-absorbing layer. During the preparation of the light-absorbing layer on the surface of the hole transport layer in the hemispherical shell array structure, the ordered hemispherical shell structure can assist in the crystal growth of the light-absorbing layer, increase the grain size of the light-absorbing layer, reduce surface roughness, reduce grain boundaries and defects, enhance light absorption, reduce carrier recombination, and improve photoelectric conversion efficiency.

[0060] In this application, the bandgap of the light-absorbing layer ranges from 1.20 eV to 2.30 eV. Perovskites with bandgap ranges of 1.20 eV to 2.30 eV can cover a wide spectrum from ultraviolet to near-infrared, meaning they can utilize most of the energy in the solar spectrum. Perovskites with bandgap ranges of 1.20 eV to 2.30 eV typically exhibit excellent carrier dynamics characteristics, including long carrier lifetimes and high mobility, which are beneficial for improving the performance of solar cells. This type of perovskite material can maintain good performance under different illumination conditions, including weak light or scattered light conditions, which helps to improve the environmental adaptability of solar cells. The thickness of the light-absorbing layer in this application ranges from 400 nm to 1000 nm, which helps to balance the generation and extraction of carriers and ensures that recombination loss does not occur due to excessive thickness before photogenerated carriers diffuse to the second electrode or interface layer for collection.

[0061] In this application, the material of the first electrode includes at least one of FTO, ITO, AZO, BZO, and IZO, and the material of the second electrode includes an inorganic conductive material, which includes at least one of Ag, Cu, graphite, Au, Al, IZO, and ITO.

[0062] Optionally, the light-absorbing layer is made of perovskite, which has the structural formula ABX3, wherein A includes inorganic cations and / or organic cations, B includes inorganic cations, and X includes inorganic anions and / or organic anions.

[0063] The light-absorbing layer in this application is made of perovskite, which is typically a class of materials with an ABX3 structure, for example, where the A site is Cs. + CH3NH2 + With CH2(NH2) + B is Pb 2+ or Sn 2+ X is a halide ion Cl. - ,Br - with I - It is a cubic close-packed structure formed by hydrogen bonding between halide octahedral BX6 and A-site cations. This organic-inorganic hybrid lead halide perovskite has advantages such as low cost, high visible light internal absorption coefficient, high carrier mobility, tunable band gap, and easy synthesis by solution method.

[0064] Optionally, the radius of A is larger than the radius of B;

[0065] And / or, the B comprises a divalent metal cation;

[0066] And / or, A includes at least one of methylamino, formamidinyl, cesium ion, and rubidium;

[0067] And / or, the B includes Pb 2+ Sn 2+ At least one of them;

[0068] And / or, the X includes Cl - ,Br - I - At least one of them.

[0069] In this application, the radius of A is larger than the radius of B. The larger A-site ion can reduce the lattice stress caused by the smaller B-site ion, which helps maintain the stability of the perovskite structure. B includes a divalent metal cation, which can usually form a more stable octahedral structure, which is crucial for maintaining the stability of the entire perovskite crystal structure. In this application, A includes at least one of methylamino, formamidinyl, cesium ion, and rubidium; B includes Pb. 2+ Sn 2+ At least one of them; X includes Cl - ,Br - I - At least one of them.

[0070] Optionally, this application provides a hole transport layer for use in a solar cell, the solar cell comprising a first electrode and a hole transport layer disposed sequentially, the hole transport layer having a plurality of concave surfaces on the side opposite to the first electrode.

[0071] Optionally, the shapes of the plurality of concave surfaces include spherical concave surfaces or near-spherical concave surfaces;

[0072] And / or, the plurality of said concave surfaces are distributed in an array.

[0073] Optionally, the structure formed by the plurality of concave surfaces includes an array of hemispherical shells;

[0074] And / or, the thickness of the hole transport layer ranges from 10 nm to 50 nm;

[0075] And / or, the material of the hole transport layer includes at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and poly(ethylenedioxythiophene-polystyrene sulfonate).

[0076] Optionally, this application also provides a method for preparing a solar cell, comprising:

[0077] Prepare the first electrode and fabricate an opal template on the first electrode;

[0078] A hole transport layer is prepared on the opal template, and the opal template is removed to obtain a hole transport layer with multiple concave surfaces on the side opposite to the first electrode.

[0079] That is, in order to prepare a hole transport layer with an inverse opal structure, an opal template is prepared on the first electrode, a hole transport layer is prepared on the opal template, and the opal template is removed to obtain a hole transport layer with multiple concave surfaces on the side opposite to the first electrode.

[0080] Optionally, the step of preparing an opal template on the first electrode includes:

[0081] The first electrode is placed in a container and immersed in a solution. A spherical particle solution is added to the container, and a surfactant solution is added dropwise. A spherical particle interface is formed at the interface between the solution and the atmosphere. After drying, an opal template is obtained on the first electrode.

[0082] Optionally, the step of preparing a hole transport layer on the opal template, removing the opal template, and obtaining the hole transport layer of the hemispherical shell array includes:

[0083] A hole transport layer is prepared on the opal template, the hole transport layer is annealed, and the opal template is immersed in an organic solvent to dissolve the opal template, thereby obtaining a hole transport layer of a hemispherical shell array.

[0084] In the process of preparing the opal template, the first electrode is placed in a container and immersed in a solution. A spherical particle solution is added to the container, and a surfactant solution is added dropwise. A spherical particle interface is formed at the interface between the solution and the atmosphere. After drying, the opal template is obtained on the first electrode.

[0085] To rapidly crystallize the hole transport layer material into a film, resulting in better crystallinity and larger grains to increase transmittance, a hole transport layer was prepared on an opal template and then annealed. The opal template was then immersed in an organic solvent to dissolve it, yielding a hole transport layer of a hemispherical shell array.

[0086] Optionally, in the step of preparing an opal template on the first electrode, the number of layers of the opal template is any one of one, two, or three layers;

[0087] And / or, in the step of preparing a hole transport layer on the opal template, the preparation method includes any one of magnetron sputtering, atomic deposition, and spin coating.

[0088] To obtain any one of the single-layer hemispherical shell array, double-layer hemispherical shell array, or triple-layer hemispherical shell array, the number of layers of the opal template can be set to one, two, or three layers.

[0089] In the step of preparing the hole transport layer, any one of magnetron sputtering, atomic deposition, or spin coating can be used.

[0090] Optionally, after the step of preparing a hole transport layer on the opal template, the method further includes preparing a light-absorbing layer on the hole transport layer and annealing the light-absorbing layer.

[0091] Optionally, this application also provides an electrical device, which includes a solar cell as described above.

[0092] Optionally, this application also provides a power generation device, which includes a solar cell as described above.

[0093] The hole transport layer of this application has multiple concave surfaces on the side facing the light-absorbing layer. The concave surfaces increase the surface area between the hole transport layer and the light-absorbing layer, resulting in a larger contact interface between the two layers. This increases the photoelectric response area between the light and the light-absorbing layer. At the same time, the increased surface area helps to extend the propagation path of light in the light-absorbing layer, improves light utilization, and thus improves the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0094] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0095] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application;

[0096] Figure 2 This is a schematic diagram of the structure of a solar cell according to another embodiment of this application;

[0097] Figure 3 This is a scanning electron microscope (SEM) image of the hole transport layer in Embodiment 1 of this application;

[0098] Figure 4 This is a cross-sectional structural diagram of the hole transport layer in Embodiment 1 of this application;

[0099] Figure 5 This is a cross-sectional structural diagram of the hole transport layer according to another embodiment of this application;

[0100] Figure 6 This is a cross-sectional structural diagram of the first electrode, hole transport layer, and light-absorbing layer in Embodiment 1 of this application;

[0101] Figure 7 This is a schematic diagram of the structure of the opal template in Embodiment 1 of this application;

[0102] Figure 8 This is a transmittance diagram of light passing through the hole transport layer in Embodiment 1 and Comparative Example 1 of this application.

[0103] Explanation of icon numbers:

[0104]

[0105]

[0106] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0107] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0108] The following detailed description of embodiments of the solar cell of this application is provided with appropriate reference to the accompanying drawings. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0109] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0110] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0111] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0112] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0113] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0114] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0115] In recent years, solar cells have developed rapidly, with efficiency improving dramatically. For example, the single-junction photoelectric conversion efficiency of perovskite solar cells has reached 26.7%, showing promising commercial prospects. The typical structure of a standard perovskite solar cell is: transparent conductive oxide / electron transport layer / perovskite light-absorbing layer / hole transport layer / metal second electrode. The structure of an inverted perovskite solar cell is: transparent conductive oxide / hole transport layer / perovskite light-absorbing layer / electron transport layer / metal second electrode, where the positions of the electron transport layer and hole transport layer are reversed.

[0116] The mainstream formal structure is FTO / SnO x The transmittance of visible light exceeds 80%, approaching the 85% transmittance of TCO glass, while the inverted structure only has around 70%. For example, the light-receiving surface of an inverted perovskite solar cell is a transparent conductive glass (TCO) / hole transport layer (e.g., NiO). x (e.g., x is 1 to 2), however, only about 70% of the visible light reaches the perovskite after passing through the TCO and hole transport layer. Increasing the transmittance of the hole transport layer and thus increasing the light utilization rate of the perovskite layer are effective ways to improve photoelectric conversion efficiency.

[0117] To improve the photoelectric conversion efficiency of solar cells, such as Figure 1As shown, the present invention proposes a solar cell, which includes a first electrode, a hole transport layer, a light-absorbing layer, and a second electrode arranged in sequence; the hole transport layer has multiple concave surfaces on the side facing the light-absorbing layer.

[0118] A concave surface refers to a surface or shape that curves inward to form a recessed space.

[0119] The hole transport layer has multiple concave surfaces on the side facing the light-absorbing layer. These concave surfaces increase the surface area between the hole transport layer and the light-absorbing layer, resulting in a larger contact interface between them. This increases the photoelectric response area of ​​the light and the light-absorbing layer. At the same time, the increased surface area helps to extend the propagation path of light in the light-absorbing layer, improving light utilization and thus enhancing the photoelectric conversion efficiency of the solar cell.

[0120] In one embodiment, the shapes of the multiple concave surfaces include spherical concave surfaces or near-spherical concave surfaces; and / or, the multiple concave surfaces are arranged in an array. The shapes of the multiple concave surfaces, including spherical concave surfaces or near-spherical concave surfaces, have a light-focusing effect, which can improve the incident light efficiency. The array arrangement of the multiple concave surfaces indicates that the multiple concave surfaces are arranged in an orderly manner, and the orderly structure can increase the surface area. It is understood that "near-spherical" refers to a shape similar to a sphere, where each part of a spherical concave surface is at a distance r from the center of the sphere, and some parts of a near-spherical concave surface may have distances greater than or less than r from the center of the sphere.

[0121] In one embodiment, the structure consisting of multiple concave surfaces includes an array of hemispherical shells.

[0122] In one embodiment, the structure composed of multiple concave surfaces includes a hemispherical shell array. The hole transport layer structure can be considered to include this hemispherical shell array, which is an inverse opal structure. Inverse opal is a special photonic crystal with a photonic bandgap effect, which improves light transmittance, allowing light to be effectively absorbed by the light-absorbing layer after passing through the hole transport layer. The hemispherical shell array structure of the hole transport layer can provide a larger surface area, resulting in a larger contact interface between the light-absorbing layer and the hole transport layer. This increases the photoelectric response area between the light and the light-absorbing layer, extends the light propagation path in the device, improves light utilization, and thus enhances the photoelectric conversion efficiency of the solar cell.

[0123] It is understandable that the hemispherical shell alignment is a single-layer structure. When using a template to prepare the inverse opal structure, a single layer of template is used to prepare a single layer of hemispherical shell alignment.

[0124] In one embodiment, the hemispherical shell array has a spherical shell array on the side facing the first electrode.

[0125] It is understandable that the inverse opal structure prepared using a single-layer template consists of a single-layer hemispherical shell array located on the surface of the hole transport layer; the inverse opal structure prepared using a double-layer template consists of a single-layer spherical shell array and a single-layer hemispherical shell array, such as... Figure 5 As shown, the hemispherical shell array is located on the surface of the hole transport layer, and the spherical shell array is located inside the hole transport layer; the inverse opal structure prepared by the three-layer template consists of two spherical shell arrays and one hemispherical shell array.

[0126] It is understandable that as the number of array layers increases, the photoelectric conversion efficiency will decrease. The more array layers there are, the thicker the hole transport layer will become, and an excessively thick hole transport layer will affect carrier transport.

[0127] like Figure 2 As shown, another solar cell proposed in this invention includes a first electrode 1, a hole transport layer 2, a light-absorbing layer 3, an electron transport layer 4, and a second electrode 5 arranged sequentially; the hole transport layer 2 has a hemispherical shell array structure.

[0128] The first electrode can be a transparent structure with light-transmitting characteristics, allowing sunlight to pass through it and enter the battery.

[0129] The hole transport layer has the function of transporting holes, which is used to transport holes to the first electrode and prevent holes from diffusing in the opposite direction.

[0130] The light-absorbing layer includes a light-absorbing material. The light-absorbing material absorbs photons from sunlight to generate excitation, which in turn excites electrons in the valence band to generate photogenerated holes and electron pairs.

[0131] The electron transport layer, located between the second electrode and the light-absorbing layer, is a layered structure used to transport electrons. It is composed of electron-transporting materials to transport electrons to the second electrode and prevent electrons from diffusing in the opposite direction.

[0132] The second electrode's main function is to collect electrons from the electron transport layer.

[0133] hemispherical shell array, such as Figure 3 and Figure 4 As shown, Figure 3 This is a scanning electron microscope image of the hole transport layer. Figure 4 This is a schematic cross-sectional view of the hole transport layer. As can be seen, multiple hemispherical shells are arranged adjacently to form a hemispherical shell array. The interior of each shell is hollow. This hemispherical shell array structure is an inverse opal structure. The inverse opal structure is a special type of photonic crystal that exhibits a photonic bandgap effect, which can improve light transmittance.

[0134] It is understandable that the periodic, ordered porous structure of the inverse opal structure makes it selective for light incident. Light of a specific wavelength selected will undergo diffuse reflection, and photons entering it are like being "trapped" and will be continuously reflected in the inverse opal structure until they are absorbed by the light-absorbing layer. Therefore, setting the hole transport layer as an inverse opal structure can improve the light transmittance.

[0135] The hemispherical array structure of the hole transport layer can provide a larger surface area, resulting in a larger contact interface between the light-absorbing layer and the hole transport layer. This increases the photoelectric response area between the light and the light-absorbing layer, extends the propagation path of light in the device, and improves the utilization rate of light.

[0136] In other words, the hole transport layer structure includes a hemispherical array, which is an inverse opal structure. Inverse opal is a special photonic crystal with a photonic bandgap effect, which improves light transmittance, allowing light to be effectively absorbed by the light-absorbing layer after passing through the hole transport layer. The hemispherical array structure of the hole transport layer can provide a larger surface area, resulting in a larger contact interface between the light-absorbing layer and the hole transport layer. This increases the photoelectric response area between the light and the light-absorbing layer, extends the light propagation path in the device, improves light utilization, and ultimately enhances the photoelectric conversion efficiency of the solar cell.

[0137] Understandably, this is because the mainstream formal structure is FTO / SnO. x With a visible light transmittance exceeding 85%, approaching that of glass, SnO employs an inverse opal structure in its formal structure. x The increase in transmittance is negligible. The formal structure basically does not have the problem of low transmittance caused by the hole transport layer in the inverse structure.

[0138] In one embodiment, the thickness of the hole transport layer ranges from 10 nm to 50 nm; in another embodiment, the refractive index of the hole transport layer is less than that of the light-absorbing layer; in one embodiment, the radius of the spherical concave surface is from 25 nm to 500 nm, for example, the radius of the hemispherical shell in the hemispherical shell array is from 25 nm to 500 nm; in one embodiment, the material of the hole transport layer includes at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and polyethylenedioxythiophene-polystyrene sulfonate; in one embodiment, the light-absorbing layer includes a crystalline material.

[0139] Taking the hole transport layer of a hemispherical shell array as an example, the thickness of the hole transport layer refers to the size of the thickest part of the hole transport layer, such as... Figure 6 As shown, the spacing D at the maximum width in the hemispherical shell array.

[0140] Understandably, the thickness of the hole transport layer in a hemispherical shell array can be measured as follows: a cross-section of the hole transport layer of the hemispherical shell array is made, and the cross-section is tested using a scanning electron microscope to obtain an image of the cross-section. The thickness of the hole transport layer corresponding to the image is then measured.

[0141] Understandably, the thickness of the hole transport layer affects performance. An excessively thick layer can impair hole transport; for example, it affects both the transport and extraction efficiency of holes. An overly thick hole transport layer may slow down hole transport, increase the probability of charge recombination, and lower the open-circuit voltage of the cell. Conversely, an excessively thin layer may not adequately cover the first electrode; for instance, if it's too thin, the light-absorbing layer might directly contact the first electrode, causing leakage current and reducing device efficiency. Therefore, employing the aforementioned thickness of the hole transport layer can improve the photoelectric conversion efficiency of solar cells.

[0142] The values ​​in the range of 10nm to 50nm include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 10nm, 20nm, 30nm, 40nm, 50nm, etc., and the range values ​​between any two of the above point values.

[0143] Refractive index, also known as the refractive index of light, is a physical quantity used to describe the degree to which the speed of light changes when it travels from one medium to another, and the degree to which the direction of light propagation is deflected. It is the ratio of the speed of light in a vacuum to the speed of light in the given medium.

[0144] In one embodiment, the refractive index of the hole transport layer is lower than that of the light-absorbing layer. This is because when incident light enters a medium with a lower refractive index, the propagation direction shifts towards the normal, resulting in a smaller refraction angle, as follows: Figure 6 As shown, at the interface between the hole transport layer 2 and the light-absorbing layer 3, the normal points towards the center of the sphere. The closer the light is to the normal during refraction, the less likely it is to escape from the side. Therefore, the refractive index of the hole transport layer is less than that of the light-absorbing layer, and more light enters the light-absorbing layer, which helps to improve the photoelectric conversion efficiency of the solar cell.

[0145] Methods for testing refractive index: Ellipsometers can be used. An ellipsometer is a technique that obtains the optical properties of a thin film by measuring the change in polarization state of linearly polarized light after reflection from a material surface. Specifically, the ellipsometer measures the ellipticity parameters Δ (Delta) and Ψ (Psi) of the reflected light; these parameters are related to the optical properties of the material surface. By fitting these parameters to a model, properties such as the refractive index and absorptivity of the thin film can be calculated.

[0146] The basic operation of an ellipsometer includes the following steps: First, linearly polarized light is generated using a light source. Then, a polarization state generator (PSG) modulates the light to produce elliptically polarized light, which is then projected onto the sample. The reflected light passes through a polarization state analyzer (PSA) to analyze the polarization state of the reflected light. Finally, a photodetector measures the intensity of the reflected light, thereby obtaining the ellipsometric parameters Δ and Ψ.

[0147] The ellipsometer measurements need to be fitted using specialized data analysis software. This software uses a computational model of the sample to predict the values ​​of Δ and Ψ and compares them with experimental measurements. By adjusting parameters in the model, such as film thickness and optical constants, the optimal match between experimental and model data can be found, thus obtaining the film thickness and optical properties. For example, the refractive index of the hole transport layer can be measured using the method described in application number CN202111658726.0.

[0148] In one embodiment, the radius of the hemispherical shells in the hemispherical shell array is between 25 nm and 500 nm. The radius of the hemispherical shells within the above range contributes to light transmittance.

[0149] Understandably, the radius of the hemispheres in the hemisphere array can be measured using a scanning electron microscope to obtain an image of the hemisphere array, and the radius of the corresponding hemisphere in the image can then be measured.

[0150] In one embodiment, the hole transport layer material includes at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and poly(ethylenedioxythiophene-polystyrene sulfonate).

[0151] In one embodiment, it is also understood that when the light-absorbing layer comprises a crystalline material, the hole transport layer serves as the substrate supporting the light-absorbing layer. During the fabrication of the light-absorbing layer on the surface of the hole transport layer in the hemispherical array structure, the ordered hemispherical structure can assist in the crystalline growth of the light-absorbing layer, increasing the grain size and reducing surface roughness. This can reduce grain boundaries and defects, enhance light absorption, reduce carrier recombination, and improve photoelectric conversion efficiency. It is understood that larger grains can provide a more direct and less obstructed path for charge carriers, thereby improving charge transport efficiency. Increased grain size can improve light scattering, helping more photons to be absorbed by the battery, thus improving photoelectric conversion efficiency. Larger grains help reduce structural deformation caused by temperature changes or mechanical stress, thereby improving the long-term stability of the battery. It is understood that reduced surface roughness helps reduce surface recombination of charges, thereby improving the overall photoelectric conversion efficiency of the battery. A smoother surface helps reduce light scattering and reflection, allowing more photons to be absorbed by the light-absorbing layer, thereby increasing the generation of photogenerated charge carriers. A smooth surface facilitates more efficient transport of charge carriers between the light-absorbing layer and the second electrode or transport layer, reducing energy loss during transport. Reduced surface roughness decreases defect sites, improving the efficient separation and transport of electron-hole pairs.

[0152] The values ​​in the range of 25nm to 500nm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 25nm, 30nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., as well as the range values ​​between any two of the above point values.

[0153] In one embodiment, the refractive index of the hole transport layer ranges from 1.8 to 2.1; in another embodiment, the refractive index of the light-absorbing layer ranges from 2.3 to 2.6; in one embodiment, a first passivation layer is provided between the hole transport layer and the light-absorbing layer; in another embodiment, a second passivation layer is provided between the light-absorbing layer and the electron transport layer; in another embodiment, a blocking layer is provided between the electron transport layer and the second electrode; in one embodiment, the material of the light-absorbing layer includes perovskite, the perovskite having the structural formula ABX3, wherein A is an inorganic cation and / or an organic cation, B is an inorganic cation and / or an organic cation, and X is an inorganic anion and / or an organic anion.

[0154] In this application, the refractive index of the hole transport layer meets the above-mentioned range, which helps to improve the absorption of light in the light-absorbing layer.

[0155] In this application, the refractive index of the light-absorbing layer meets the above-mentioned range, which helps to improve the absorption of light in the light-absorbing layer.

[0156] In this application, a first passivation layer is provided between the hole transport layer and the light-absorbing layer. It is understood that the passivation layer is used to passivate surface / interface defects of the hole transport layer, reduce charge carrier recombination, and thus improve the photoelectric conversion efficiency of the battery. In particular, the hole transport layer of the inverse opal structure of this application has an uneven thickness. Especially in the structure of a single-layer hemispherical array, in the thinnest region, the light-absorbing layer may directly contact the first electrode, generating leakage current. To reduce this risk, a first passivation layer is provided between the light-absorbing layer and the hole transport layer.

[0157] In this application, a second passivation layer is provided between the light-absorbing layer and the electron transport layer to reduce charge carrier recombination.

[0158] This application incorporates a barrier layer between the electron transport layer and the second electrode. This barrier layer has a deep valence band level, effectively blocking majority carriers (holes) from transporting to the second electrode. In other words, the barrier layer typically has a deep valence band level. This design effectively blocks majority carriers (holes) from passing through while allowing minority carriers (electrons) to transport to the second electrode. This selective transport helps reduce recombination of electrons and holes before they reach the second electrode, thereby improving the photoelectric conversion efficiency of the solar cell.

[0159] Furthermore, during the deposition process using physical vapor deposition techniques such as magnetron sputtering, high-energy particles may damage the underlying film layer, causing lattice defects or changes in chemical structure. Barrier layers can act as protective layers to reduce this damage. In other words, barrier layers can improve the crystal quality and interface quality of the electron transport layer, thereby enhancing electron transport efficiency and overall device performance.

[0160] The light-absorbing layer in this application is made of perovskite, which is typically a class of materials with an ABX3 structure, for example, where the A site is Cs. + CH3NH2 + With CH2(NH2) + B is Pb 2+ or Sn 2+ X is a halide ion Cl. - ,Br - with I - It is a cubic close-packed structure formed by hydrogen bonding between halide octahedral BX6 and A-site cations. This organic-inorganic hybrid lead halide perovskite has advantages such as low cost, high visible light internal absorption coefficient, high carrier mobility, tunable band gap, and easy synthesis by solution method.

[0161] In one embodiment, the refractive index of the hole transport layer is less than the refractive index of the first passivation layer; in one embodiment, the thickness of the first passivation layer is less than the maximum depth of the concave surface, for example, the thickness of the first passivation layer is less than the radius of the hemisphere in the hemispherical array, and the maximum depth of the concave surface refers to the perpendicular distance from the lowest point in the concave geometry to the reference plane (the plane where the light-absorbing layer is located); in one embodiment, the radius of A is greater than the radius of B; in one embodiment, B comprises a divalent metal cation; in one embodiment, the bandgap of the light-absorbing layer ranges from 1.20 eV to 2.30 eV; in one embodiment, the thickness of the light-absorbing layer ranges from 400 nm to 1000 nm. nm; In one embodiment, the material of the first passivation layer includes at least one of 3-triethoxysilylpropionitrile, 2-aminothiazolyl-4-acetic acid, and 1-hydroxy-4-carbonylbenzene; In one embodiment, the material of the second passivation layer includes at least one of piperazine, N-methyl-1,3-propanediammonium diiodide, 3-aminopyridine, and ferrocene; In one embodiment, the material of the barrier layer includes at least one of indium tungsten oxide, indium tin oxide, copper bath, and zirconium acetylacetonate; In one embodiment, the material of the first electrode includes at least one of FTO, ITO, AZO, BZO, and IZO; In one embodiment, the material of the electron transport layer includes at least one of methyl [6,6]-phenyl-C61-butyrate, methyl [6,6]-phenyl-C71-butyrate, fullerene and its derivatives, tin dioxide, and zinc oxide; In one embodiment, the material of the second electrode includes an inorganic conductive material, which includes at least one of Ag, Cu, graphite, Au, Al, IZO, and ITO.

[0162] In this application, the refractive index of the hole transport layer is less than that of the first passivation layer. Since the incident light will deviate towards the normal when it enters the medium with a low refractive index, it is not easy for it to exit from the side. In the process of light entering the first passivation layer from the hole transport layer, it helps to increase the probability of light entering the first passivation layer.

[0163] In this application, the thickness of the first passivation layer is less than the radius of the hemispherical shell in the hemispherical shell array. In this way, the contact interface between the first passivation layer and the light-absorbing layer is still spherical, which helps the light to be deflected from the first passivation layer into the light-absorbing layer towards the normal and to converge towards the center of the sphere, thereby increasing the probability of the light entering the light-absorbing layer.

[0164] In this application, the radius of A is larger than that of B. The larger A-site ion can reduce the lattice stress caused by the smaller B-site ion, which helps maintain the stability of the perovskite structure. B includes divalent metal cations, which can usually form a more stable octahedral structure, which is crucial for maintaining the stability of the entire perovskite crystal structure. In this application, the bandgap range of the light-absorbing layer is 1.20 eV to 2.30 eV. Perovskites with a bandgap in the range of 1.20 eV to 2.30 eV can cover a wide spectrum from ultraviolet to near-infrared, which means that they can utilize most of the energy in the solar spectrum. Perovskites with a bandgap in the range of 1.20 eV to 2.30 eV usually have excellent carrier dynamics characteristics, including long carrier lifetime and high mobility, which is beneficial to improving the performance of solar cells. Perovskite materials with this type of bandgap can maintain good performance under different illumination conditions, including weak light or scattered light conditions, which helps to improve the environmental adaptability of solar cells. The thickness of the light-absorbing layer in this application ranges from 400 nm to 1000 nm, which helps to balance the generation and extraction of charge carriers and ensures that recombination loss will not occur due to excessive thickness before the photogenerated charge carriers diffuse to the second electrode or are collected at the interface layer.

[0165] The material of the first passivation layer in this application includes at least one of 3-triethoxysilylpropionitrile, 2-aminothiazolyl-4-acetic acid, and 1-hydroxy-4-carbonylbenzene. These materials are self-assembled molecules with π-π conjugation. The π-π conjugated part can interact with the perovskite. In addition, the nitrile group, carboxyl group, hydroxyl group, etc. in the molecule can form chemical bonds with the hole transport layer to achieve anchoring. That is, the first passivation layer strengthens the tightness between the perovskite thin layer and the hole transport layer, reduces the generation of pinholes, passivates surface defects, reduces non-radiative recombination, and improves the photoelectric conversion efficiency of the solar cell.

[0166] The material of the second passivation layer includes at least one of piperazine, N-methyl-1,3-propanediammonium diiodide, 3-aminopyridine, and ferrocene; the material of the barrier layer includes at least one of indium tungsten oxide, indium tin oxide, copper bath, and zirconium acetylacetonate; the material of the first electrode includes at least one of FTO, ITO, AZO, BZO, and IZO. The FTO conductive glass is fluorine-doped SnO2 transparent conductive glass (SnO2:F), abbreviated as FTO. The ITO conductive glass is deposited on a sodium-calcium-based or silicon-boron-based substrate glass using a magnetron sputtering method. The upper layer is made of indium tin oxide (commonly known as ITO) film. AZO is the abbreviation for aluminum-doped zinc oxide (ZnO) transparent conductive glass, BZO is boron-doped zinc oxide, and IZO is indium zinc oxide. The electron transport layer material includes at least one of [6,6]-phenyl-C61-butyrate methyl ester, [6,6]-phenyl-C71-butyrate methyl ester, fullerene and its derivatives, tin dioxide, and zinc oxide. The second electrode material includes inorganic conductive materials, including at least one of Ag, Cu, graphite, Au, Al, IZO, and ITO.

[0167] In one embodiment, the thickness of the first passivation layer ranges from 0.5 nm to 3 nm; in one embodiment, the refractive index of the first passivation layer ranges from 1.9 to 2.3; in one embodiment, A comprises at least one selected from methylamino, formamidinyl, cesium ions, and rubidium; in one embodiment, B comprises Pb. 2+ Sn 2+ At least one of them; in one embodiment, X includes Cl - ,Br - I - At least one of them.

[0168] In one embodiment, the thickness of the first passivation layer ranges from 0.5 nm to 3 nm. It is understood that an excessively thick passivation layer can affect the transport of charge carriers, and the thickness of the first passivation layer within the above range can reduce the impact of the passivation layer thickness on the charge carriers.

[0169] The values ​​in the range of 0.5nm to 3nm include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 0.5nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, etc., as well as the range values ​​between any two of the above point values.

[0170] In one embodiment, the refractive index of the first passivation layer meeting the above-mentioned range helps to improve light absorption in the light-absorbing layer.

[0171] In one embodiment, A comprises at least one selected from methylamino, formamidinyl, cesium ion, and rubidium; B comprises Pb. 2+ Sn2+ At least one of them; X includes Cl - ,Br - I - At least one of them.

[0172] In one embodiment, this application provides a hole transport layer for use in a solar cell. The solar cell includes a first electrode and a hole transport layer disposed sequentially, and the hole transport layer has multiple concave surfaces on the side opposite to the first electrode.

[0173] In one embodiment, the shapes of the plurality of concave surfaces include spherical concave surfaces or near-spherical concave surfaces; and / or, the plurality of concave surfaces are distributed in an array.

[0174] In one embodiment, the structure comprising multiple concave surfaces includes a hemispherical shell array; and / or, the thickness of the hole transport layer ranges from 10 nm to 50 nm; and / or, the material of the hole transport layer includes at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and polyethylenedioxythiophene-polystyrene sulfonate.

[0175] In one embodiment, this application also provides a method for fabricating a solar cell, comprising: preparing a first electrode; fabricating an opal template on the first electrode; fabricating a hole transport layer on the opal template; removing the opal template to obtain a hole transport layer having multiple concave surfaces on the side opposite to the first electrode.

[0176] That is, in order to prepare a hole transport layer with an inverse opal structure, an opal template is prepared on the first electrode, a hole transport layer is prepared on the opal template, and the opal template is removed to obtain a hole transport layer with multiple concave surfaces on the side opposite to the first electrode.

[0177] In one embodiment, the step of preparing an opal template on the first electrode includes: placing the first electrode in a container, immersing it in a solution, adding a spherical particle solution to the container, adding a surfactant solution dropwise, forming a spherical particle interface at the interface between the solution and the atmosphere, and drying to obtain an opal template on the first electrode; in another embodiment, the step of preparing a hole transport layer on the opal template, removing the opal template, and obtaining a hole transport layer of a hemispherical shell array includes: preparing a hole transport layer on the opal template, annealing the hole transport layer, and immersing the opal template in an organic solvent to dissolve the opal template to obtain a hole transport layer of a hemispherical shell array.

[0178] In the process of preparing the opal template, the first electrode is placed in a container and immersed in a solution. A spherical particle solution is added to the container, and a surfactant solution is added dropwise. A spherical particle interface is formed at the interface between the solution and the atmosphere. After drying, the opal template is obtained on the first electrode.

[0179] To rapidly crystallize the hole transport layer material into a film, resulting in better crystallinity and larger grains to increase transmittance, a hole transport layer was prepared on an opal template and then annealed. The opal template was then immersed in an organic solvent to dissolve it, yielding a hole transport layer of a hemispherical shell array.

[0180] In one embodiment, in the step of preparing an opal template on the first electrode, the number of layers of the opal template is any one of one, two, or three layers; in one embodiment, in the step of preparing a hole transport layer on the opal template, the preparation method includes any one of magnetron sputtering, atomic deposition, or spin coating.

[0181] To obtain any one of the single-layer hemispherical shell array, double-layer hemispherical shell array, or triple-layer hemispherical shell array, the number of layers of the opal template can be set to one, two, or three layers.

[0182] In the step of preparing the hole transport layer, any one of magnetron sputtering, atomic deposition, or spin coating can be used.

[0183] In one embodiment, after the step of preparing a hole transport layer on an opal template, the method further includes preparing a light-absorbing layer on the hole transport layer and annealing the light-absorbing layer.

[0184] In one embodiment, this application also provides an electrical device, which includes a solar cell as described above.

[0185] Electrical appliances refer to devices or systems that consume electrical energy and convert it into other forms of energy. Electrical appliances may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these. Since solar cells employ all the technical solutions of the above embodiments, they possess at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0186] In one embodiment, this application also provides a power generation device, which includes a solar cell as described above.

[0187] A power generation device refers to a device or system capable of converting some form of energy into electrical energy. The power generation device in this application utilizes solar cells to receive sunlight and convert light energy into electrical energy. For example, a power generation device is a solar panel, typically composed of multiple solar cells, which converts sunlight into electrical energy. Since the solar cell employs all the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0188] Example

[0189] Preparation of opal precursor solution: Polystyrene (PS) microsphere colloids were prepared by emulsion polymerization. First, 135 mL of deionized water was added to a 250 mL three-necked flask and heated to 80 °C in a water bath. Then, 0.06 g of sodium dodecyl sulfate (SDS) and 15 g of styrene monomer were added to the mixture, and after stirring for 10 minutes, 0.15 g of potassium persulfate (KPS) was added, and stirring continued for 25 hours. After natural cooling, a 200 nm PS microsphere colloidal solution was obtained. The particle size of the PS microspheres could be controlled by adjusting the reaction temperature, stirring time, stirring speed, and the type and concentration of the initiator during emulsion polymerization.

[0190] NiO x Preparation of precursor solution: Dissolve 0.1 mmol of Ni(Ac)₂·4H₂O in 1 mL of isopropanol, add ethanolamine (EA), Ni 2+ / The molar ratio of EA was maintained at 1:1. The solution was stored in a sealed glass bottle and stirred overnight in air at 70°C to obtain a homogeneous green solution.

[0191] Example 1

[0192] Substrate preparation: First, the FTO substrate was ultrasonically cleaned for 10 minutes each with deionized water, ethanol, and acetone.

[0193] Preparation of the opal template: The above PS colloidal solution was diluted with ethanol and deionized water at a 1:1 volume ratio. The prepared FTO substrate was placed in a circular petri dish and surrounded by deionized water. 100 μL of PS emulsion was slowly added to the center of the petri dish, followed by the dropwise addition of 2% sodium dodecyl sulfate aqueous solution, forming an ordered monolayer PS sphere interface at the water-air interface. Finally, the sample was dried in a 60°C oven to obtain a monolayer ordered opal template.

[0194] Preparation of hole transport layer: NiO was spin-coated onto an FTO / opal template at 1500 rpm at room temperature. x Precursor solution for 30 s, then NiO x The film was annealed at 200°C for 1 hour. NiO x The thickness is 20 nm. Then FTO / opal template / NiO is applied. x The sample was soaked in chlorobenzene / toluene / dichloromethane to dissolve the PS spherical template, and then dried to obtain a single-layer inverse opal structure NiO. x The refractive index is 2.0.

[0195] Preparation of the light-absorbing layer: PbI₂ and MAI methylammonium iodide (molar ratio = 1:1) were dissolved in a mixed solution of DMF and DMSO (volume ratio = 4:1) to obtain a 1.2 M perovskite precursor solution. The solution was then filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter. In an argon-filled glove box, 60 μL of the perovskite precursor solution was spread over the hole transport layer and spin-coated at 4000 rpm for 30 s. 200 μL of the antisolvent chlorobenzene was rapidly and uniformly added to the perovskite film between the 8th and 10th s after the start of spin-coating. The sample was annealed at 105 °C for 10 min to obtain a well-crystallized perovskite layer with a refractive index of 2.5.

[0196] Preparation of electron transport layer: A layer of PCBM (chlorobenzene solution of 20 mg / mL [6,6]-phenyl-C61-butyrate) was spin-coated on the perovskite layer at 1500 rpm for 45 seconds and annealed at 100 °C for 40 min.

[0197] Preparation of the barrier layer: BCP copper bath solution (0.5 mg / mL isopropanol solution) was spin-coated onto PCBM at 5000 rpm for 60 s to obtain a barrier layer (10 nm).

[0198] Preparation of the second electrode: A gold layer of approximately 50 nm was deposited using a vacuum deposition apparatus as the second electrode.

[0199] Example 2

[0200] Based on Example 1, a NiO with a double-layered inverse opal structure was prepared. x .

[0201] Preparation of the opal template: The above PS colloidal solution was diluted with ethanol and deionized water at a 1:1 volume ratio. The prepared FTO substrate was placed in a circular petri dish and surrounded by deionized water. 300 μL of PS emulsion was slowly added to the center of the petri dish, followed by the dropwise addition of 2% sodium dodecyl sulfate aqueous solution, forming an ordered bilayer PS sphere interface at the water-air interface. Finally, the sample was dried in a 60°C oven to obtain a bilayer ordered opal template.

[0202] Preparation of the hole transport layer: At room temperature, a NiOx precursor solution was spin-coated onto an FTO / opal template at 1500 rpm for 30 s, and then NiO was... x The film was annealed at 200°C for 1 hour. The NiOx thickness was 20 nm. Then, FTO / opal template / NiO was applied. x The sample was soaked in chlorobenzene / toluene / dichloromethane to dissolve the PS spherical template, and then dried to obtain NiO with a double-layered inverse opal structure. x .

[0203] Example 3

[0204] Based on Example 1, a first passivation layer (with a thickness of 0.5 nm and a refractive index of 2.1) is provided between the hole transport layer and the light absorption layer.

[0205] Preparation of passivation layer: In NiO with inverse opal structure x Me-4PACz solution (methyl 4-(N,N-dimethylamino)phenyl-C61-butyrate 0.5 mg / mL ethanol solution) was spin-coated at 4000 rpm for 30 s, followed by annealing at 100 °C for 10 min to obtain the passivation layer Me-4PACz.

[0206] Examples 4 and 5

[0207] The material of the hole transport layer was adjusted based on Example 1.

[0208] Comparative Example 1

[0209] Based on Example 1, the hole transport layer has a non-inverse opal structure. NiO was spin-coated onto a clean FTO substrate at 1500 rpm at room temperature. x Precursor solution for 30 s, then NiO x The thin film was annealed at 200°C for 1 hour, NiO x The thickness is 20nm.

[0210] Scanning electron microscopy (SEM) test

[0211] The samples were tested using a ZEISS sigma 300 scanning electron microscope, and then the morphology of the samples was observed according to standard JY / T010-1996. For example... Figure 7 The image shown is a scanning electron microscope (SEM) image of PS microspheres on an FTO surface. Figure 3 As shown, this is an inverse opal NiO on an FTO surface. x Scanning electron microscope image.

[0212] Transmittance testing was performed using a UV-Vis-NIR spectrophotometer. A blank sample or no sample was placed in the sample chamber. In the instrument control window, the wavelength range of 300nm-800nm ​​was entered, and baseline calibration was initiated by clicking "OK". After baseline calibration, the sample to be tested was placed in the sample end of the sample chamber, and the cover was closed. Sample information was entered in the instrument control window to perform the test. Figure 8 As shown, the FTO / inverse opal structure hole transport layer in Test Example 1 and the FTO / hole transport layer in Comparative Example 1 are tested.

[0213] Photovoltaic conversion efficiency of perovskite solar cells

[0214] The current-voltage characteristic curves of the battery under illumination were measured using a four-channel Keithley 2400SMU digital source meter. Under atmospheric conditions, the simulated solar light source used was an AM 1.5G solar irradiance source at 100 mW / cm². 2 Battery performance was tested under a specific light source.

[0215] The photoelectric conversion efficiency is calculated as follows:

[0216] PCE = Pout / Popt

[0217] =Voc×Jsc×(Vmpp×Jmpp) / (Voc×Jsc)

[0218] =Voc×Jsc×FF

[0219] Where Pout, Popp, Vmpp, Jmpp, Voc, and Jsc are the battery's operating output power, incident light power, battery's maximum power point voltage, battery's maximum power point current, open-circuit voltage, and short-circuit current, respectively.

[0220] Table 1. List of Experimental Data

[0221]

[0222] As shown in Table 1, setting the hole transport layer as an inverse opal structure improves the light transmittance through the hole transport layer and also enhances the photoelectric conversion efficiency of the solar cell. Furthermore, the photoelectric conversion efficiency decreases with increasing number of inverse opal structure array layers, indicating that a larger number of inverse opal structure array layers leads to a thicker hole transport layer, which can negatively impact carrier transport.

[0223] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A solar cell, characterized in that, The solar cell includes a first electrode, a hole transport layer, a light absorption layer, and a second electrode which are arranged in sequence; One side of the hole transport layer facing the light absorption layer has a plurality of concave surfaces.

2. The solar cell as described in claim 1, characterized in that, The shapes of the plurality of concave surfaces include spherical concave surfaces or quasi-spherical concave surfaces; And / or, the plurality of concave surfaces are arranged in an array.

3. The solar cell as described in claim 1 or 2, characterized in that, The structure formed by the plurality of concave surfaces includes a hemispherical shell array.

4. The solar cell as described in claim 3, characterized in that, One side of the hemispherical shell array facing the first electrode has a spherical shell array.

5. The solar cell according to any one of claims 2 to 4, characterized in that, The radius of the spherical concave surface is from 25 nm to 500 nm.

6. The solar cell according to any one of claims 1 to 5, characterized in that, The thickness range of the hole transport layer is from 10 nm to 50 nm.

7. The solar cell according to any one of claims 1 to 6, characterized in that, The refractive index of the hole transport layer is less than that of the light absorption layer.

8. The solar cell according to any one of claims 1 to 7, characterized in that, The material of the hole transport layer includes at least one of nickel oxide, poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine), and poly(ethylenedioxythiophene)-polystyrene sulfonate.

9. The solar cell as claimed in claim 7, characterized in that, The refractive index range of the hole transport layer is from 1.8 to 2.

1.

10. The solar cell as claimed in claim 7, characterized in that, The refractive index range of the light absorption layer is from 2.3 to 2.

6.

11. The solar cell according to any one of claims 1 to 10, characterized in that, A first passivation layer is provided between the hole transport layer and the light absorption layer; And / or, an electron transport layer is provided between the light absorption layer and the second electrode.

12. The solar cell as described in claim 11, characterized in that, The refractive index of the hole transport layer is less than that of the first passivation layer; And / or, the thickness of the first passivation layer is less than the maximum depth of the concave surface; And / or, a second passivation layer is provided between the light absorption layer and the electron transport layer; And / or, a blocking layer is provided between the electron transport layer and the second electrode.

13. The solar cell as described in claim 11 or 12, characterized in that, The thickness range of the first passivation layer is from 0.5 nm to 3 nm; [[ID= ​ 14. The solar cell as described in claim 12 or 13, characterized in that, ​ ​ ​ 15. The solar cell according to any one of claims 1 to 14, characterized in that, ​ ​ ​ 16. The solar cell according to any one of claims 1 to 15, characterized in that, ​ ​ ​ 17. The solar cell as described in claim 16, characterized in that, ​ And / or, the B comprises a divalent metal cation; And / or, A includes at least one of methylamino, formamidinyl, cesium ion, and rubidium; And / or, the B includes Pb 2+ Sn 2+ At least one of them; And / or, the X includes Cl - ,Br - I - At least one of them.

18. A hole transport layer, applied to a solar cell, characterized in that, The solar cell includes a first electrode and a hole transport layer arranged sequentially, and the hole transport layer has multiple concave surfaces on the side opposite to the first electrode.

19. The hole transport layer as described in claim 18, characterized in that, The shapes of the plurality of concave surfaces include spherical concave surfaces or near-spherical concave surfaces; And / or, the plurality of said concave surfaces are distributed in an array.

20. The hole transport layer as described in claim 18 or 19, characterized in that, The structure formed by the multiple concave surfaces includes a hemispherical shell array; And / or, the thickness of the hole transport layer ranges from 10 nm to 50 nm; And / or, the material of the hole transport layer includes at least one of nickel oxide, poly(4-phenyl)(2,4,6-trimethylphenyl)amine, and poly(ethylenedioxythiophene-polystyrene sulfonate).

21. A method for preparing a solar cell, characterized in that, include: Prepare the first electrode and fabricate an opal template on the first electrode; A hole transport layer is prepared on the opal template, and the opal template is removed to obtain a hole transport layer with multiple concave surfaces on the side opposite to the first electrode.

22. The method for preparing a solar cell as described in claim 21, characterized in that, The step of preparing an opal template on the first electrode includes: The first electrode is placed in a container and immersed in a solution. A spherical particle solution is added to the container, and a surfactant solution is added dropwise. A spherical particle interface is formed at the interface between the solution and the atmosphere. After drying, an opal template is obtained on the first electrode.

23. The method for preparing a solar cell as described in claim 21 or 22, characterized in that, The step of preparing a hole transport layer on the opal template, removing the opal template, and obtaining the hole transport layer of the hemispherical shell array includes: A hole transport layer is prepared on the opal template, the hole transport layer is annealed, and the opal template is immersed in an organic solvent to dissolve the opal template, thereby obtaining a hole transport layer of a hemispherical shell array.

24. The method for preparing a solar cell according to any one of claims 21 to 23, characterized in that, In the step of preparing an opal template on the first electrode, the number of layers of the opal template is any one of one, two, or three layers; And / or, in the step of preparing a hole transport layer on the opal template, the preparation method includes any one of magnetron sputtering, atomic deposition, and spin coating.

25. The method for preparing a solar cell according to any one of claims 21 to 24, characterized in that, After the step of preparing a hole transport layer on the opal template, the method further includes preparing a light-absorbing layer on the hole transport layer and annealing the light-absorbing layer.

26. An electrical appliance, characterized in that, The electrical device includes a solar cell as claimed in any one of claims 1 to 17.

27. A power generation device, characterized in that, The power generation device includes a solar cell as described in any one of claims 1 to 17.

Images