Perovskite solar cells, photovoltaic modules

Abstract

The application provides a perovskite solar cell and a photovoltaic module. The perovskite solar cell comprises a first electrode, a second electrode and a light-absorbing layer between the first electrode and the second electrode. The perovskite solar cell further comprises a first hole transport layer and a second hole transport layer. The first hole transport layer is between the second hole transport layer and the light-absorbing layer. The second hole transport layer is between the first electrode and the light-absorbing layer, or the second hole transport layer is between the second electrode and the light-absorbing layer. The first hole transport material of the first hole transport layer is selected from one of PTAA, doped or undoped nickel oxide with a first doping element. The second hole transport material of the second hole transport layer comprises at least one of a P-type transition metal oxide semiconductor material and a P-type transition metal halide semiconductor material capable of isolating water and oxygen.

Description

[0001] This application is a divisional application based on the invention with application number 202180094972.X, application date December 3, 2021, applicant CATL, and invention title "Perovskite Solar Cells and Photovoltaic Modules". Technical Field

[0002] This application belongs to the field of solar cell technology, specifically relating to a perovskite solar cell and a photovoltaic module. Background Technology

[0003] With the development of modern industry, global energy shortages and environmental pollution have become increasingly prominent, making solar cells, as an ideal renewable energy source, increasingly important. Solar cells, also known as photovoltaic cells, are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. Improving the photoelectric conversion efficiency of solar cells has always been a research focus. Perovskite solar cells utilize perovskite materials as the light-absorbing layer, and they rapidly achieved high photoelectric conversion efficiency within a few years of their invention, attracting widespread attention in recent years. When perovskite materials absorb incident sunlight, they generate electron-hole pairs, which are then separated into electrons and holes and transported to the cathode and anode, respectively. Accelerating hole transport and preventing electron-hole recombination are crucial for improving the photoelectric conversion efficiency of perovskite solar cells. Summary of the Invention

[0004] The purpose of this application is to provide a perovskite solar cell and photovoltaic module, which aims to improve the hole extraction and transmission efficiency of the hole transport layer, increase the turn-on voltage and current of the perovskite solar cell, and improve the photoelectric conversion efficiency and lifespan of the perovskite solar cell.

[0005] This application provides a perovskite solar cell, comprising a first electrode, a second electrode, and a light-absorbing layer located between the first electrode and the second electrode. The perovskite solar cell further includes a first hole transport layer and a second hole transport layer. The first hole transport layer is located between the second hole transport layer and the light-absorbing layer, or the second hole transport layer is located between the first electrode and the light-absorbing layer, or the second hole transport layer is located between the second electrode and the light-absorbing layer. The first hole transport material of the first hole transport layer is selected from PTAA, nickel oxide doped or undoped with a first doping element, and the second hole transport material of the second hole transport layer includes at least one of a P-type transition metal oxide semiconductor material capable of isolating water and oxygen, and a P-type transition metal halide semiconductor material.

[0006] In the perovskite solar cell of this application, the first hole transport material is located close to the light-absorbing layer, enabling efficient extraction of holes from the light-absorbing layer. The second hole transport material has better surface wettability and film-forming properties, thereby improving the bonding strength between the overall hole transport layer and the electrode. The second hole transport material can also form a passivation protective layer on the surface of the first hole transport layer to passivate the surface of the first hole transport layer and prevent the first hole transport material from denaturing or degrading upon contact with air; at the same time, the passivation protective layer can also isolate water and oxygen, preventing water and oxygen from corroding the first hole transport material, thus better utilizing the hole extraction and transport capabilities of the first hole transport material. The second hole transport material can also improve the overall conductivity of the hole transport layer, thereby further improving the hole extraction and transport efficiency. The second hole transport material has fewer internal crystal defects and can also block further migration of charged halide ions, thereby improving the stability of the perovskite solar cell. Therefore, this application can effectively reduce the recombination of electrons and holes, improve the extraction and transport efficiency of holes, and enable more holes to be transported to one of the first electrode and the second electrode, thereby improving the turn-on voltage and current of the perovskite solar cell, and improving the photoelectric conversion efficiency and lifespan of the perovskite solar cell.

[0007] In any embodiment of this application, the energy difference ΔVBM1 between the valence band top level of the second hole transport layer and the first hole transport layer is -1.0 eV to 1.0 eV. In the perovskite solar cell of this application, the second hole transport layer and the first hole transport layer have a suitable energy difference between their valence band top levels, and the hole transport layer as a whole has a suitable energy level gradient, which is beneficial for reducing electron-hole recombination, improving hole extraction and transport efficiency, and reducing energy loss. When the energy difference between the second hole transport layer and the first hole transport layer is too large, it will cause excessive energy loss due to hole transitions between energy levels. Optionally, the energy difference ΔVBM1 between the second hole transport layer and the first hole transport layer is -0.3 eV to 0.3 eV. A smaller energy difference between the second hole transport layer and the first hole transport layer is beneficial for further reducing electron-hole recombination, improving hole transport efficiency, and reducing energy loss.

[0008] In any embodiment of this application, the first doping element includes at least one selected from alkali metals, alkaline earth metals, transition metals, and halogens. Optionally, the alkali metal element includes at least one selected from Li, Na, K, Rb, and Cs. Optionally, the alkaline earth metal element includes at least one selected from Be, Mg, Ca, Sr, and Ba. Optionally, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au. Optionally, the halogen element includes at least one selected from F, Cl, Br, and I. After nickel oxide is doped with the first doping element, the photoelectric properties of the first hole transport layer can be altered, thereby better matching the energy levels of the first hole transport layer and the light-absorbing layer, improving the hole extraction efficiency, and ultimately improving the photoelectric conversion efficiency of the perovskite solar cell.

[0009] In any embodiment of this application, the mass percentage of the first dopant element is ≤20% based on the total mass of the first hole transport material. Optionally, the mass percentage of the first dopant element is 5%~15%. Choosing an appropriate doping amount is beneficial for better adjusting the band structure of the first hole transport layer. If the mass percentage of the first dopant element is too high, it may damage the crystal structure of nickel oxide, causing a large band structure deviation and affecting the hole extraction and transport capabilities of the first hole transport layer.

[0010] In any embodiment of this application, the second hole transport material includes at least one of the following materials, either doped or undoped by a second doping element: MoO3, CuO, Cu2O, CuI, NiMgLiO, CuGaO2, CuGrO2, and CoO. These hole transport materials can better isolate water and oxygen, inhibit the corrosion of the first hole transport material by water and oxygen, and improve hole transport efficiency.

[0011] In any embodiment of this application, the second doping element includes at least one selected from alkali metals, alkaline earth metals, transition metals, metal-depleted elements, metalloids, halogens, nonmetals, ionic liquids, carboxylic acids, phosphoric acid, carbon derivatives, self-assembled monomers, and polymers. Optionally, the alkali metal element includes at least one selected from Li, Na, K, Rb, and Cs. Optionally, the alkaline earth metal element includes at least one selected from Be, Mg, Ca, Sr, and Ba. Optionally, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au. Optionally, the metal-depleted element includes at least one selected from Al, Ga, In, Sn, Tl, Pb, and Bi. Optionally, the metalloid element includes at least one selected from B, Si, Ge, As, Sb, and Te. Optionally, the halogen element includes at least one selected from F, Cl, Br, and I. Optionally, the nonmetal element includes at least one selected from P, S, and Se. Optionally, the ionic liquid includes at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, NH4Cl, (NH4)2S, tetramethylammonium hydroxide aqueous solution, and trifluoroethanol. Optionally, the carboxylic acid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 4-imidazolium acetate hydrochloride, and acetic acid. Optionally, the carbon derivative includes carbon quantum dots, carbon nanotubes, graphene, and C. 60 g-C3N4, C9, NPC 60 -OH, DPC 60 At least one of the following. Optionally, the self-assembled monomer includes at least one of 2-phenylethylamine hydroiodate, N,N-diethylaniline, 9,9-bis(4-aminophenyl)fluorene, 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane, and glycine. Optionally, the polymer includes at least one of styrene, polyethyleneimine, polyethylene oxide, and tris(N,N-tetramethylene)phosphoramide.

[0012] By doping the second hole transport material, the band structure of the second hole transport layer can be adjusted, resulting in a suitable valence band top energy difference and energy gradient between the second and first hole transport layers. This reduces electron-hole recombination, improves hole extraction and transport efficiency, and increases the turn-on voltage and current of perovskite solar cells. Doping the second hole transport material also improves its conductivity.

[0013] In any embodiment of this application, the mass percentage of the second dopant element is ≤30% based on the total mass of the second hole transport material. Optionally, the mass percentage of the second dopant element is 5%~25%. Selecting an appropriate doping amount is beneficial for better adjusting the band structure of the second hole transport layer, so that the second hole transport layer and the first hole transport layer have a suitable valence band top energy level difference and a suitable energy level gradient, thereby reducing electron-hole recombination and improving hole extraction and transport efficiency.

[0014] In any embodiment of this application, the energy difference ΔVBM2 between the valence band top level of the first hole transport layer and the light-absorbing layer is -1.0 eV to 1.0 eV. Optionally, the energy difference ΔVBM2 between the valence band top level of the first hole transport layer and the light-absorbing layer is -0.3 eV to 0.3 eV. Having the energy difference between the valence band top level of the first hole transport layer and the light-absorbing layer within a suitable range is beneficial for the first hole transport layer to extract holes from the light-absorbing layer more efficiently.

[0015] In any embodiment of this application, the energy difference between the conduction band top level of the second hole transport layer and the light-absorbing layer is ≥0.5 eV. When the energy difference between the conduction band top level of the second hole transport layer and the light-absorbing layer is within a suitable range, it can block electron transport and reduce the recombination of electrons and holes.

[0016] In any embodiment of this application, the energy difference between the conduction band top level of the first hole transport layer and the light-absorbing layer is ≥0.5 eV. When the energy difference between the conduction band top level of the first hole transport layer and the light-absorbing layer is within a suitable range, it can block electron transport and reduce the recombination of electrons and holes.

[0017] In any embodiment of this application, the difference between the Fermi level and the top valence band level of the second hole transport layer is ≤1.5 eV. A smaller difference between the Fermi level and the top valence band level of the second hole transport layer ensures that the second hole transport layer has better P-type semiconductor characteristics, which is beneficial for improving hole transport capability.

[0018] In any embodiment of this application, the difference between the Fermi level and the top valence band level of the first hole transport layer is ≤1.5 eV. A smaller difference between the Fermi level and the top valence band level of the first hole transport layer ensures that the first hole transport layer has better P-type semiconductor characteristics, which is beneficial for improving hole extraction and transport capabilities.

[0019] In any embodiment of this application, the band gap of the second hole transport layer is ≥1.5 eV. A second hole transport layer with a larger band gap can better filter ultraviolet light and reduce the damage of ultraviolet light to light-absorbing materials.

[0020] In any embodiment of this application, the thickness of the second hole transport layer is 1 nm to 300 nm. Optionally, the thickness of the second hole transport layer is 1 nm to 100 nm.

[0021] In any embodiment of this application, the thickness of the first hole transport layer is 5 nm to 1000 nm. Optionally, the thickness of the first hole transport layer is 10 nm to 200 nm.

[0022] In any embodiment of this application, the thickness ratio of the first hole transport layer to the thickness of the second hole transport layer is 1:1 to 10:1. Compared with the first hole transport layer, the second hole transport layer is thinner, denser, and more stable, which is beneficial to improving the hole transport rate.

[0023] In any embodiment of this application, the light-absorbing layer comprises a perovskite material.

[0024] In any embodiment of this application, one of the first electrode and the second electrode is a transparent electrode. Optionally, the transparent electrode is an FTO electrode or an ITO electrode.

[0025] In any embodiment of this application, one of the first electrode and the second electrode is a metal electrode or a conductive carbon electrode. Optionally, the metal electrode is selected from one or more of gold, silver, aluminum, and copper electrodes.

[0026] In any embodiment of this application, the perovskite solar cell further includes an electron transport layer located between the light-absorbing layer and the second electrode or the first electrode, and the light-absorbing layer located between the first hole transport layer and the electron transport layer. The electron transport layer can reduce the potential barrier between the electrode and the light-absorbing layer, promote electron transport, and effectively block holes, suppressing electron-hole recombination.

[0027] A second aspect of this application provides a photovoltaic module, including the perovskite solar cell of the first aspect of this application.

[0028] The photovoltaic module of this application includes the perovskite solar cell provided in this application, and therefore has at least the same advantages as the perovskite solar cell. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of one embodiment of the perovskite solar cell of this application.

[0031] Figure 2This is a schematic diagram of another embodiment of the perovskite solar cell of this application. Detailed Implementation

[0032] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the perovskite solar cells and photovoltaic modules of this application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0033] 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.

[0034] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0035] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0036] 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 method may also 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 it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0037] 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.

[0038] 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).

[0039] Perovskite solar cells utilize perovskite material as a light-absorbing layer. When sunlight strikes the layer, it is absorbed by the perovskite. The energy of the photons excites electrons previously bound to atomic nuclei, creating free electrons. Each excitation generates a hole, forming an electron-hole pair. These pairs are then separated into electrons and holes, which flow to the cathode and anode of the perovskite solar cell, respectively. During electron and hole transport, some carrier losses are inevitable, such as electron-hole recombination. The hole transport layer is a crucial functional layer in perovskite solar cells, playing a vital role in extracting and transporting holes while simultaneously blocking electrons to prevent electron-hole recombination. This is essential for improving the photoelectric conversion efficiency of perovskite solar cells.

[0040] The hole transport layer of perovskite solar cells is typically made of nickel oxide (NiO). xAs an inorganic hole transport material, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is used as an organic hole transport material. Both materials are inexpensive and possess high structural stability. Nickel oxide and PTAA also have suitable work functions and band positions, which better match the energy level structure of the perovskite material in the light-absorbing layer, ensuring hole extraction and transport. However, nickel oxide and PTAA films exhibit poor surface wettability, affecting film quality. Furthermore, the Ni content in the bulk phase after nickel oxide film formation... 3+ This enables it to conduct electricity through holes, while the portion of Ni present on the surface... 3+ It readily reacts with oxygen in the environment to form NiO and NiOOH, which not only increases the resistivity of the hole transport layer surface but also hinders hole extraction and transport. PTAA is a polymeric hole transport material, which typically has high resistivity, also making it unfavorable for hole extraction and transport.

[0041] In view of the above problems, the inventors improved the structure of the hole transport layer.

[0042] The first aspect of the embodiments of this application provides a perovskite solar cell. Figure 1 This is a schematic diagram of one embodiment of the perovskite solar cell of this application. Figure 2 This is a schematic diagram of another embodiment of the perovskite solar cell of this application. Figure 1 and Figure 2 As shown, the perovskite solar cell includes a first electrode 1, a second electrode 5, and a light-absorbing layer 3 located between the first electrode 1 and the second electrode 5. The perovskite solar cell also includes a first hole transport layer 21 and a second hole transport layer 22, with the first hole transport layer 21 located between the second hole transport layer 22 and the light-absorbing layer 3. Figure 1 As shown, the second hole transport layer 22 is located between the first electrode 1 and the light-absorbing layer 3. Figure 2 As shown, the second hole transport layer 22 is located between the second electrode 5 and the light-absorbing layer 3.

[0043] The first hole transport material of the first hole transport layer 21 is selected from PTAA, nickel oxide doped or undoped with a first doping element. The second hole transport material of the second hole transport layer 22 is selected from at least one of a P-type transition metal oxide semiconductor material capable of isolating water and oxygen, and a P-type transition metal halide semiconductor material.

[0044] The first hole transport material is close to the light-absorbing layer, which can efficiently extract holes from the light-absorbing layer. The second hole transport material has better surface wettability and film-forming properties, which helps to improve the bonding strength between the hole transport layer as a whole and the electrode (e.g., the first electrode or the second electrode).

[0045] The second hole transport material can also form a passivation protective layer on the surface of the first hole transport layer to passivate the surface of the first hole transport layer and prevent the first hole transport material from denaturing or degrading due to contact with air (e.g., some Ni on the surface of nickel oxide). 3+ The first hole transport layer is susceptible to hole extraction and transport due to its tendency to react with oxygen in the environment to form NiO and NiOOH. The second hole transport material is selected from at least one of p-type transition metal oxide semiconductor materials and p-type transition metal halide semiconductor materials that can isolate water and oxygen. Therefore, the second hole transport material can also inhibit the corrosion of the first hole transport material (e.g., PTAA, nickel oxide) by water and oxygen. Therefore, combining the first and second hole transport layers can better utilize the hole extraction and transport capabilities of the first hole transport layer. The shallow surface of the nickel oxide film contains NiO. 2+ Oxygen vacancies reduce charge and hinder hole extraction and transport. The transition metal cations in the second hole transport material can diffuse into the shallow surface of nickel oxide to some extent, replenishing lost charge and vacancies, passivating the nickel oxide surface, and isolating it from water and oxygen, thus better utilizing nickel oxide's hole extraction and transport capabilities.

[0046] After the second hole transport material forms a passivation protective layer on the nickel oxide surface, it can also reduce the resistivity of the nickel oxide surface, improve the conductivity of the first hole transport layer surface and the hole transport layer as a whole, and thus improve the hole extraction and transport efficiency. Furthermore, PTAA is a polymeric hole transport material with typically high resistivity. Combining the first and second hole transport layers can improve the overall conductivity of the hole transport layer, thereby improving the hole extraction and transport efficiency.

[0047] The light-absorbing materials in perovskite solar cells are typically halide perovskite materials (e.g., inorganic halide perovskite materials, organic halide perovskite materials, or organic-inorganic hybrid halide perovskite materials). These materials have attracted widespread attention due to their advantages such as large carrier diffusion lengths, easily tunable band gaps, high defect tolerance, and low manufacturing costs. However, halide perovskite materials themselves have poor stability and are prone to decomposition under the influence of water and oxygen, accelerating the aging of perovskite solar cells. Ion migration is another important characteristic of halide perovskite materials. The migration and accumulation of charged ions can lead to significant changes in the doping concentration of the light-absorbing layer and the built-in electric field, and may even cause local crystal structure alterations. Ion migration and accumulation can also cause local chemical doping effects, altering the Fermi level in the ion accumulation region, causing the level to bend, thereby affecting the separation, transport, and extraction of photogenerated carriers. Ion migration is closely related to defects. Defects inside the crystal provide a path for ions to migrate. In the perovskite solar cell of the present invention, the second hole transport material has fewer internal defects and is more compact and stable than the first hole transport layer. It can block further migration of charged halide ions, thereby improving the stability of the perovskite solar cell.

[0048] Therefore, the perovskite solar cell of this application can effectively reduce the recombination of electrons and holes, improve the extraction and transport efficiency of holes, and enable more holes to be transported to one of the first electrode and the second electrode, thereby improving the turn-on voltage and current of the perovskite solar cell, and improving the photoelectric conversion efficiency and lifespan of the perovskite solar cell.

[0049] In some embodiments, the first hole transport material is selected from nickel oxide doped with a first doping element. Doping nickel oxide with the first doping element can alter the photoelectric properties of the first hole transport layer, such as transparency, band structure, work function, carrier density, and conductivity, thereby better matching the energy levels of the first hole transport layer and the light-absorbing layer, improving hole extraction efficiency, and ultimately enhancing the photoelectric conversion efficiency of the perovskite solar cell.

[0050] In some embodiments, the first dopant element includes at least one selected from alkali metals, alkaline earth metals, transition metals, and halogens. Selecting a suitable first dopant element facilitates better adjustment of the band structure of the first hole transport layer.

[0051] As an example, the alkali metal element includes at least one selected from Li, Na, K, Rb, and Cs. Optionally, the alkali metal element includes at least one selected from Li, Na, and K.

[0052] As an example, the alkaline earth metal element includes at least one selected from Be, Mg, Ca, Sr, and Ba. Optionally, the alkaline earth metal element includes at least one selected from Be, Mg, and Ca. Further, the alkaline earth metal element includes Mg.

[0053] As an example, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au. Optionally, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Cu, and Mo. Further, the transition metal element includes at least one selected from Co and Cu.

[0054] As an example, the halogen element includes at least one selected from F, Cl, Br, and I. Optionally, the halogen element includes at least one selected from F and Cl.

[0055] There are no particular restrictions on the form of the first dopant element; for example, it can be in atomic, molecular, or ionic form. As an example, the precursors used to form the first dopant element include, but are not limited to, at least one of alkali metal elements, alkaline earth metal elements, transition metal elements, halogen elements, alkali metal halides, alkaline earth metal halides, and transition metal halides.

[0056] In some embodiments, the mass percentage of the first dopant element is ≤20% based on the total mass of the first hole transport material. For example, the mass percentage of the first dopant element is a range consisting of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or higher. Optionally, the mass percentage of the first dopant element is 1%~20%, 2%~20%, 3%~20%, 4%~20%, 5%~20%, 1%~15%, 2%~15%, 3%~15%, 4%~15%, 5%~15%, 1%~10%, 2%~10%, 3%~10%, 4%~10%, 1%~5%, 2%~5%, 3%~5%, or 4%~5%. Selecting an appropriate doping amount is beneficial for better adjusting the band structure of the first hole transport layer. If the mass percentage of the first dopant element is too high, it may damage the crystal structure of nickel oxide, causing a large band structure deviation and affecting the hole extraction and transmission capabilities of the first hole transport layer.

[0057] The type and content of the first doping element can be selected according to requirements. The first doping element can be one type or a combination of multiple types.

[0058] In some embodiments, the second hole transport material of the second hole transport layer 22 includes at least one of the following materials, either doped or undoped by a second doping element: MoO3, CuO, Cu2O, CuI, NiMgLiO, CuGaO2, CuGrO2, and CoO. These hole transport materials can better isolate water and oxygen, inhibit the corrosion of the first hole transport material (e.g., PTAA, nickel oxide), and improve hole transport efficiency. The transition metal cations of these hole transport materials have radii close to those of nickel ions, allowing them to better diffuse into the shallow surface of nickel oxide, thus replenishing related charge losses and vacancies, passivating the nickel oxide surface, and isolating water and oxygen.

[0059] Optionally, the second hole transport material of the second hole transport layer 22 includes at least one of the following materials that are doped or undoped by the second doping element: MoO3, CuI, and NiMgLiO.

[0060] In some embodiments, the second hole transport material is doped with a second dopant element. By doping the second hole transport material, the band structure of the second hole transport layer can be adjusted, resulting in a suitable valence band top energy difference and energy level gradient between the second and first hole transport layers. This reduces electron-hole recombination, improves hole extraction and transport efficiency, and increases the turn-on voltage and current of the perovskite solar cell. Doping the second hole transport material also improves its conductivity.

[0061] In some embodiments, the second dopant element includes at least one of alkali metals, alkaline earth metals, transition metals, metal-poor elements, metalloids, halogens, nonmetals, ionic liquids, carboxylic acids, phosphoric acid, carbon derivatives, self-assembled monomolecules, and polymers. Selecting a suitable second dopant element facilitates better tuning of the band structure of the second hole transport layer.

[0062] As an example, the alkali metal element includes at least one selected from Li, Na, K, Rb, and Cs. Optionally, the alkali metal element includes at least one selected from Li, Na, and K.

[0063] As an example, the alkaline earth metal element includes at least one selected from Be, Mg, Ca, Sr, and Ba. Optionally, the alkaline earth metal element includes at least one selected from Be, Mg, and Ca. Further, the alkaline earth metal element includes Mg.

[0064] As an example, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au. Optionally, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Ni, Cu, and Mo. Further, the transition metal element includes at least one selected from Co and Cu.

[0065] As an example, the depleted metal element includes at least one selected from Al, Ga, In, Sn, Tl, Pb, and Bi. Optionally, the depleted metal element includes at least one selected from Al and Ga. Further, the depleted metal element includes Al.

[0066] As an example, the metalloid element includes at least one selected from B, Si, Ge, As, Sb, and Te. Optionally, the metalloid element includes at least one selected from B and Sb. Further, the metalloid element includes B.

[0067] As an example, the halogen element includes at least one selected from F, Cl, Br, and I. Optionally, the halogen element includes at least one selected from F and Cl.

[0068] As an example, the nonmetallic element includes at least one of P, S, and Se. Optionally, the nonmetallic element includes P.

[0069] As an example, the ionic liquid includes at least one selected from 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), NH4Cl, (NH4)2S, tetramethylammonium hydroxide aqueous solution (TMAH), and trifluoroethanol. Optionally, the ionic liquid includes at least one selected from BMIMBF4 and NH4Cl. Further, the ionic liquid includes NH4Cl.

[0070] As an example, the carboxylic acid includes at least one selected from ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), 4-imidazolium acetate hydrochloride (ImAcHCl), and acetic acid. Optionally, the carboxylic acid includes EDTA.

[0071] As an example, the carbon derivatives include carbon quantum dots, carbon nanotubes, graphene, and C. 60 g-C3N4, C9, NPC 60 -OH, DPC 60 At least one of the following. Optionally, the carbon derivative includes carbon quantum dots.

[0072] As an example, the self-assembled monomolecule includes at least one selected from 2-phenylethylamine hydroiodide (PEAI), N,N-diethylaniline (DEA), 9,9-bis(4-aminophenyl)fluorene (FDA), 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane (APTES), and glycine. Optionally, the self-assembled monomolecule includes at least one selected from PEAI, DEA, FDA, and dopamine. Further, the self-assembled monomolecule includes PEAI.

[0073] As an example, the polymer includes at least one of polystyrene (PS), polyethyleneimine (PEIE), polyethylene oxide (PEO), and tris(N,N-tetramethylene)phosphoramide (TPPO). Optionally, the polymer includes PEIE.

[0074] There are no particular restrictions on the morphology of the second dopant element; for example, it can be in atomic, molecular, or ionic form. As examples, precursors used to form the second dopant element include, but are not limited to, at least one of the following: alkali metal elements, alkaline earth metal elements, transition metal elements, metal-poor elements, metalloid elements, halogen elements, non-metallic elements, ionic liquids, carboxylic acids, phosphoric acid, carbon derivatives, self-assembled monomolecules, polymers, alkali metal halides, alkaline earth metal halides, transition metal halides, metal-poor halides, and metalloid halides.

[0075] In some embodiments, the mass percentage of the second dopant element is ≤30% based on the total mass of the second hole transport material. For example, the mass percentage of the second dopant element is a range consisting of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or higher. Optionally, the mass percentage of the second dopant element is 1%~30%, 2%~30%, 3%~30%, 4%~30%, 5%~30%, 1%~25%, 2%~25%, 3%~25%, 4%~25%, 5%~25%, 1%~20%, 2%~20%, 3%~20%, 4%~20%, 5%~20%, 1%~15%, 2%~15%, 3%~15%, 4%~15%, 5%~15%, 1%~10%, 2%~10%, 3%~10%, 4%~10%, 1%~5%, 2%~5%, 3%~5%, or 4%~5%. Selecting an appropriate doping amount helps to better adjust the band structure of the second hole transport layer, ensuring that the second hole transport layer and the first hole transport layer have a suitable valence band top energy difference and a suitable energy level gradient, reducing electron-hole recombination and improving hole extraction and transport efficiency. If the mass percentage of the second dopant element is too high, it may damage the crystal structure of the second hole transport material, causing a large band structure deviation and affecting the performance of the second hole transport layer.

[0076] The types and amounts of the second doping element can be selected according to requirements. The second doping element can be one type or a combination of multiple types.

[0077] In some embodiments, the energy difference ΔVBM1 between the valence band top level of the second hole transport layer 22 and the first hole transport layer 21 is -1.0 eV to 1.0 eV. In perovskite solar cells, efficient hole transport relies on good energy level matching between the light-absorbing layer and the hole transport layer. In the perovskite solar cell of this application embodiment, the hole transport layer as a whole has a suitable energy level gradient, and the energy difference ΔVBM1 between the valence band top level of the second hole transport layer and the first hole transport layer is -1.0 eV to 1.0 eV. When the second hole transport layer and the first hole transport layer have a suitable energy difference between their valence band top levels, electron-hole recombination can be effectively reduced, hole extraction and transport efficiency can be improved, and more holes can be transported to either the first electrode or the second electrode, thereby improving the turn-on voltage and current of the perovskite solar cell, and increasing the photoelectric conversion efficiency and lifespan of the perovskite solar cell. When the difference between the valence band top energy level of the second hole transport layer and the first hole transport layer is too large, it will cause excessive energy loss of holes during transitions between energy levels. For example, in some cases, it may generate extra phonons, which not only consumes charge energy but also affects the thermal stability of perovskite solar cells.

[0078] In some embodiments, the energy difference ΔVBM1 between the valence band top level of the second hole transport layer 22 and the first hole transport layer 21 is -0.8 eV to 0.8 eV, -0.7 eV to 0.7 eV, -0.6 eV to 0.6 eV, -0.5 eV to 0.5 eV, -0.4 eV to 0.4 eV, or -0.3 eV to 0.3 eV. A smaller energy difference between the valence band top level of the second hole transport layer and the first hole transport layer is beneficial for further reducing electron-hole recombination, improving hole transport efficiency, and reducing energy loss.

[0079] In some embodiments, the energy difference ΔVBM2 between the valence band top level of the first hole transport layer 21 and the light-absorbing layer 3 is -1.0 eV to 1.0 eV. Optionally, the energy difference ΔVBM2 between the first hole transport layer 21 and the light-absorbing layer 3 is -0.8 eV to 0.8 eV, -0.7 eV to 0.7 eV, -0.6 eV to 0.6 eV, -0.5 eV to 0.5 eV, -0.4 eV to 0.4 eV, or -0.3 eV to 0.3 eV. A suitable range of energy difference between the valence band top levels of the first hole transport layer and the light-absorbing layer facilitates more efficient hole extraction from the light-absorbing layer by the first hole transport layer.

[0080] In some embodiments, the energy difference between the conduction band top level of the second hole transport layer 22 and the light-absorbing layer 3 is ≥0.5 eV. When the energy difference between the conduction band top levels of the second hole transport layer and the light-absorbing layer is within a suitable range, it can block electron transport and reduce the recombination of electrons and holes.

[0081] In some embodiments, the energy difference between the conduction band top level of the first hole transport layer 21 and the light-absorbing layer 3 is ≥0.5 eV. When the energy difference between the conduction band top levels of the first hole transport layer and the light-absorbing layer is within a suitable range, it can block electron transport and reduce the recombination of electrons and holes.

[0082] In some embodiments, the difference between the Fermi level and the top valence band level of the second hole transport layer 22 is ≤1.5 eV. A smaller difference between the Fermi level and the top valence band level of the second hole transport layer ensures that the second hole transport layer has better P-type semiconductor characteristics, which is beneficial for improving hole transport capability.

[0083] In some embodiments, the difference between the Fermi level and the top valence band level of the first hole transport layer 21 is ≤1.5 eV. A smaller difference between the Fermi level and the top valence band level of the first hole transport layer ensures that the first hole transport layer has better P-type semiconductor characteristics, which is beneficial for improving hole extraction and transport capabilities.

[0084] In some embodiments, the band gap of the second hole transport layer 22 is ≥1.5 eV. A second hole transport layer with a larger band gap can better filter ultraviolet light and reduce the damage of ultraviolet light to light-absorbing materials (e.g., perovskite materials).

[0085] The thickness of the first hole transport layer 21 is not specifically limited and can be selected according to actual needs. In some embodiments, the thickness of the first hole transport layer 21 is 5nm to 1000nm. Optionally, the thickness of the first hole transport layer 21 is 10nm to 200nm.

[0086] The thickness of the second hole transport layer 22 is not specifically limited and can be selected according to actual needs. In some embodiments, the thickness of the second hole transport layer 22 is 1 nm to 300 nm. Optionally, the thickness of the second hole transport layer 22 is 1 nm to 100 nm.

[0087] In some embodiments, the thickness ratio of the first hole transport layer 21 to the thickness of the second hole transport layer 22 is 1:1 to 10:1. Optionally, the thickness ratio of the first hole transport layer 21 to the thickness of the second hole transport layer 22 is 1.5:1 to 10:1, 2:1 to 10:1, 3:1 to 10:1, 4:1 to 10:1, or 5:1 to 10:1. Compared with the first hole transport layer, the second hole transport layer is thinner, has a denser film, and is more stable, thereby improving the hole transport rate.

[0088] In some embodiments, the light-absorbing layer 3 comprises a perovskite material. As an intrinsic semiconductor material, the perovskite material can transport both electrons and holes; therefore, in a perovskite solar cell, it can serve as both a light-absorbing layer and an electron or hole transport layer.

[0089] The types of perovskite materials are not specifically limited and can be selected according to actual needs. In some embodiments, perovskite materials may include one or more of inorganic halide perovskite materials, organic halide perovskite materials, and organic-inorganic hybrid halide perovskite materials. The molecular formula of the perovskite material may be ABX3, where A represents an inorganic cation, an organic cation, or a mixed organic-inorganic cation, B represents an inorganic cation, an organic cation, or a mixed organic-inorganic cation, and X represents an inorganic anion, an organic anion, or a mixed organic-inorganic anion.

[0090] As an example, A is selected from CH3NH3 + (MA) + CH(NH2)2 + (FA) + ), Li + Na + K + 、Rb + Cs + One or more of them. Optionally, A is selected from CH3NH3. + CH(NH2)2 + Cs + One or more of them.

[0091] As an example, B is selected from Pb. 2+ Sn 2+ Be 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Zn 2+ 、Ge 2+ Fe 2+ Co 2+ Ni 2+ One or more of them. Optionally, B is selected from Pb. 2+ Sn 2+ One or two of them.

[0092] As an example, X is selected from F - Cl - ,Br - I - One or more of them. Optionally, X is selected from Cl. - ,Br - I - One or more of them.

[0093] In some embodiments, the perovskite material includes, but is not limited to, one or more of CH3NH3PbI3 (MAPbI3), CH(NH2)2PbI3 (FAPbI3), CsPbI3, CsPbI2Br, and CsPbIBr2.

[0094] In some embodiments, the thickness of the light-absorbing layer 3 is 50 nm to 2000 nm.

[0095] In some embodiments, the material of the first electrode 1 is not specifically limited and can be selected according to actual needs. For example, the material of the first electrode 1 is an organic conductive material, an inorganic conductive material, or a mixed organic-inorganic conductive material.

[0096] In some embodiments, the material of the second electrode 5 is not specifically limited and can be selected according to actual needs. For example, the material of the second electrode 5 is an organic conductive material, an inorganic conductive material, or a mixed organic-inorganic conductive material.

[0097] In some embodiments, one of the first electrode 1 and the second electrode 5 is a transparent electrode. In some embodiments, both the first electrode 1 and the second electrode 5 are transparent electrodes. Optionally, the transparent electrode is an FTO (fluorine-doped tin oxide, SnO2:F) electrode, an ITO (indium-doped tin oxide, SnO2:In2O3) electrode, an AZO (aluminum-doped zinc oxide) electrode, a BZO (boron-doped zinc oxide) electrode, or an IZO (indium zinc oxide) electrode. Optionally, the transparent electrode is an FTO electrode or an ITO electrode.

[0098] In some embodiments, one of the first electrode 1 and the second electrode 5 is a metal electrode or a conductive carbon electrode. Optionally, the metal electrode is selected from one or more of gold, silver, aluminum, and copper electrodes.

[0099] In some embodiments, the thickness of the first electrode 1 is not specifically limited and can be selected according to actual needs. For example, it can be 50 nm to 1000 nm.

[0100] In some embodiments, the thickness of the second electrode 5 is not specifically limited and can be selected according to actual needs. For example, it can be 10 nm to 500 nm.

[0101] like Figure 1 and Figure 2 As shown, in some embodiments, the perovskite solar cell further includes an electron transport layer 4. The electron transport layer 4 is located between the light-absorbing layer 3 and the second electrode 5 or the first electrode 1, and the light-absorbing layer 3 is located between the first hole transport layer 21 and the electron transport layer 4. The electron transport layer can reduce the potential barrier between the electrode and the light-absorbing layer, promote electron transport, and effectively block holes, suppressing electron-hole recombination.

[0102] In some embodiments, the thickness of the electron transport layer 4 is not specifically limited and can be selected according to actual needs. For example, it can be 20 nm to 300 nm.

[0103] In some embodiments, the electron transport material of the electron transport layer 4 is not specifically limited and can be selected according to actual needs. For example, the electron transport material is selected from organic electron transport materials, inorganic electron transport materials, or organic-inorganic hybrid electron transport materials.

[0104] As an example, the electron transport material is selected from at least one of the following materials: imide compounds, quinone compounds, fullerenes and their derivatives, 2,2',7,7'-tetratetra(N,N-p-methoxyaniline)-9,9'-spirodifluorene (Spiro-OMeTAD), methoxytriphenylamine-fluoroformamidinium (OMeTPA-FA), poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), poly3-hexylthiophene (P3HT), triphenylamine with a triphenylene core (H101), and 3,4-ethylenedioxythiophene-methoxy Triphenylamine (EDOT-OMeTPA), N-(4-aniline)carbazole-spirobisfluorene (CzPAF-SBF), polythiophene, metal oxides (metal elements selected from Mg, Ni, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, or Cr), silicon dioxide (SiO2), strontium titanate (SrTiO3), calcium titanate (CaTiO3), lithium fluoride (LiF), calcium fluoride (CaF2), and cuprous thiocyanate (CuSCN).

[0105] Optionally, the electron transport material is selected from one or more fullerenes and their derivatives. For example, the electron transport material is selected from PC. 60 BM, PC 70 One or more of the BMs. The conduction band bottom level of fullerenes and their derivatives can be better matched with the conduction band bottom level of the light-absorbing layer, thereby promoting electron extraction and transport.

[0106] In some embodiments, the perovskite solar cell includes a first electrode 1, a second hole transport layer 22, a first hole transport layer 21, a light-absorbing layer 3, an electron transport layer 4, and a second electrode 5, arranged sequentially. The energy difference ΔVBM1 between the top valence band of the second hole transport layer 22 and the first hole transport layer 21 is -1.0 eV to 1.0 eV. The first hole transport material of the first hole transport layer 21 is selected from PTAA, nickel oxide doped or undoped with a first doping element, and the second hole transport material of the second hole transport layer 22 includes at least one of the following materials doped or undoped with a second doping element: MoO3, CuI, and NiMgLiO.

[0107] In some embodiments, the perovskite solar cell includes a first electrode 1, an electron transport layer 4, a light-absorbing layer 3, a first hole transport layer 21, a second hole transport layer 22, and a second electrode 5, arranged sequentially. The energy difference ΔVBM1 between the top valence band of the second hole transport layer 22 and the first hole transport layer 21 is -1.0 eV to 1.0 eV. The first hole transport material of the first hole transport layer 21 is selected from PTAA, nickel oxide doped or undoped with a first doping element, and the second hole transport material of the second hole transport layer 22 includes at least one of the following materials doped or undoped with a second doping element: MoO3, CuI, and NiMgLiO.

[0108] The perovskite solar cell of the first aspect of this application is not limited to the structure described above, and may also include other functional layers. For example, in some embodiments, the perovskite solar cell further includes a hole-blocking layer located between the light-absorbing layer and the electron transport layer. In some embodiments, the perovskite solar cell further includes an electrode modification layer for modifying the first electrode or the second electrode. The electrode modification layer can reduce the energy level barrier between the light-absorbing layer and the first electrode or the second electrode, thereby playing the role of transporting holes while blocking electrons or transporting electrons while blocking holes.

[0109] Perovskite solar cells can be fabricated according to methods known in the art. One exemplary fabrication method includes the steps of: fabricating a first electrode, forming a second hole transport layer on the first electrode, forming a first hole transport layer on the second hole transport layer, forming a light-absorbing layer on the first hole transport layer, forming an electron transport layer on the light-absorbing layer, and forming a second electrode on the electron transport layer. Another exemplary fabrication method includes: fabricating a first electrode, forming an electron transport layer on the first electrode, forming a light-absorbing layer on the electron transport layer, forming a first hole transport layer on the light-absorbing layer, forming a second hole transport layer on the first hole transport layer, and forming a second electrode on the second hole transport layer.

[0110] The methods for forming the above-mentioned films are not specifically limited and can be any film-forming methods known in the art, such as chemical bath deposition, chemical vapor deposition, electrochemical deposition, physical epitaxial growth, thermal evaporation, atomic layer deposition, precursor liquid slot coating, precursor liquid blade coating, sol-gel method, magnetron sputtering, pulsed laser deposition, etc.

[0111] The band distribution of each film layer can be determined by X-ray photoelectron spectroscopy (XPS) or ultraviolet photoelectron spectroscopy (UPS).

[0112] The perovskite solar cell of the first aspect of the embodiments of this application can be used alone as a single-junction perovskite solar cell, or it can be made into a tandem solar cell with perovskite or other types of solar cells, such as a perovskite-perovskite tandem solar cell or a perovskite-crystalline silicon tandem solar cell.

[0113] photovoltaic modules A second aspect of the embodiments of this application also provides a photovoltaic module, the photovoltaic module including the perovskite solar cell of the first aspect of the embodiments of this application, the perovskite solar cell can be used as the power source of the photovoltaic module after being connected in series and parallel and encapsulated.

[0114] In some embodiments, the photovoltaic module includes a single-junction perovskite solar cell, a perovskite-perovskite tandem solar cell, or a perovskite-crystalline silicon tandem solar cell according to the first aspect of the present application.

[0115] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0116] Example 1 Preparation of ITO electrodes: Take a set of ITO-coated glass substrates with dimensions of 2.0 cm × 2.0 cm, clean the surface twice with acetone and isopropanol respectively, then immerse them in deionized water for ultrasonic treatment for 10 min, dry them in a forced-air drying oven, and then place them in a glove box (N2 atmosphere).

[0117] Preparation of the second hole transport layer: A precursor solution was prepared by adding KCl to a CuI chlorobenzene solution with a concentration of 0.08 mol / L, wherein the concentration of KCl was 3 g / L. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300℃ for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0118] Preparation of the first hole transport layer: NiO with a concentration of 3wt% was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm. x The nanocolloid aqueous solution was then heated at 300°C for 60 min on a constant temperature hot stage to obtain a first hole transport layer with a thickness of 15 nm.

[0119] Preparation of light-absorbing layer: A MAPbI3 dimethylformamide solution with a concentration of 1.5 mol / L was spin-coated onto the first hole transport layer at a speed of 3000 rpm to 4500 rpm. The layer was then heated at 100 °C for 30 min on a constant temperature hot stage and cooled to room temperature to obtain an absorbing layer with a thickness of 800 nm.

[0120] Fabrication of electron transport layer: PC at a concentration of 20 mg / mL was spin-coated onto the obtained absorbent layer at a speed of 800 rpm to 1500 rpm. 60 The BM chlorobenzene solution was then heated at 100°C for 10 min on a constant temperature hot plate to obtain an electron transport layer with a thickness of 60 nm.

[0121] Preparation of Ag electrode: The aforementioned sample was placed in a vacuum coating machine and subjected to a 5×10⁻⁶ temperature. -4 An Ag electrode with a thickness of 100 nm was deposited on the surface of the obtained electron transport layer under vacuum conditions of Pa.

[0122] The final perovskite solar cell structure obtained in Example 1 is ITO / doped CuI / NiO. x / MAPbI3 / PC 60 BM / Ag.

[0123] Example 2 Preparation of ITO electrodes: Same as Example 1.

[0124] Preparation of the second hole transport layer: A precursor solution was prepared by adding KI to a CuI aqueous solution with a concentration of 0.08 mol / L, wherein the concentration of KI was 3 g / L. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300 °C for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0125] Preparation of the first hole transport layer A PTAA toluene solution with a concentration of 2 mg / mL was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm, and then heated at 100 °C for 10 min on a constant temperature hot plate to obtain a first hole transport layer with a thickness of 15 nm.

[0126] Preparation of light-absorbing layer: Same as Example 1.

[0127] Fabrication of electron transport layer: Same as Example 1.

[0128] Preparation of Ag electrode: Same as Example 1.

[0129] The final perovskite solar cell structure obtained in Example 2 is ITO / doped CuI / PTAA / MAPbI3 / PC. 60 BM / Ag.

[0130] Example 3 Preparation of ITO electrodes: Same as Example 1.

[0131] Preparation of the second hole transport layer A precursor solution was prepared by adding KCl to a 0.08 mol / L MoO3 chlorobenzene solution, wherein the concentration of KCl was 3 g / L. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300℃ for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0132] Preparation of the first hole transport layer NiO with a concentration of 3wt% was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm. x The nanocolloid aqueous solution was then heated at 300°C for 60 min on a constant temperature hot stage to obtain a first hole transport layer with a thickness of 15 nm.

[0133] Preparation of light-absorbing layer: Same as Example 1.

[0134] Fabrication of electron transport layer:Same as Example 1.

[0135] Preparation of Ag electrode: Same as Example 1.

[0136] The final perovskite solar cell structure obtained in Example 3 is ITO / doped MoO3 / NiO. x / MAPbI3 / PC 60 BM / Ag.

[0137] Example 4 Preparation of ITO electrodes: Same as Example 1.

[0138] Preparation of the second hole transport layer: A precursor solution was prepared by adding KCl to a 0.08 mol / L MoO3 colloidal aqueous solution, wherein the concentration of KCl was 3 g / L. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300℃ for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0139] Preparation of the first hole transport layer A PTAA toluene solution with a concentration of 2 mg / mL was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm, and then heated at 100 °C for 10 min on a constant temperature hot plate to obtain a first hole transport layer with a thickness of 15 nm.

[0140] Preparation of light-absorbing layer: Same as Example 1.

[0141] Fabrication of electron transport layer: Same as Example 1.

[0142] Preparation of Ag electrode: Same as Example 1.

[0143] The final perovskite solar cell structure obtained in Example 4 is ITO / doped MoO3 / PTAA / MAPbI3 / PC. 60 BM / Ag.

[0144] Example 5 Preparation of ITO electrodes: Same as Example 1.

[0145] Preparation of the second hole transport layer A precursor solution was prepared by adding KCl to a NiMgLiO chlorobenzene solution with a concentration of 0.08 mol / L and a KCl concentration of 3 g / L. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300 °C for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0146] Preparation of the first hole transport layer NiO with a concentration of 3wt% was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm. x The nanocolloid aqueous solution was then heated at 300°C for 60 min on a constant temperature hot stage to obtain a first hole transport layer with a thickness of 15 nm.

[0147] Preparation of light-absorbing layer: Same as Example 1.

[0148] Fabrication of electron transport layer: Same as Example 1.

[0149] Preparation of Ag electrode: Same as Example 1.

[0150] The final perovskite solar cell structure obtained in Example 5 is ITO / doped NiMgLiO / NiO x / MAPbI3 / PC 60 BM / Ag.

[0151] Example 6 Preparation of ITO electrodes: Same as Example 1.

[0152] Preparation of the second hole transport layer: A precursor solution was prepared by adding KCl to a NiMgLiO colloidal aqueous solution with a concentration of 0.08 mol / L, wherein the concentration of KCl was 3 g / L. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300℃ for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0153] Preparation of the first hole transport layer: A PTAA toluene solution with a concentration of 2 mg / mL was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm, and then heated at 100 °C for 10 min on a constant temperature hot plate to obtain a first hole transport layer with a thickness of 15 nm.

[0154] Preparation of light-absorbing layer: Same as Example 1.

[0155] Fabrication of electron transport layer: Same as Example 1.

[0156] Preparation of Ag electrode: Same as Example 1.

[0157] The final perovskite solar cell structure obtained in Example 6 is ITO / doped NiMgLiO / PTAA / MAPbI3 / PC. 60 BM / Ag.

[0158] Example 7 Preparation of ITO electrodes: Same as Example 1.

[0159] Preparation of the second hole transport layer: A precursor solution was prepared by adding lithium carbonate to a 0.08 mol / L MoO3 colloidal aqueous solution, wherein the concentration of lithium carbonate was 10%. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300 °C for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0160] Preparation of the first hole transport layer: A PTAA toluene solution with a concentration of 2 mg / mL was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm, and then heated at 100 °C for 10 min on a constant temperature hot plate to obtain a first hole transport layer with a thickness of 15 nm.

[0161] Preparation of light-absorbing layer: Same as Example 1.

[0162] Fabrication of electron transport layer: Same as Example 1.

[0163] Preparation of Ag electrode: Same as Example 1.

[0164] The final perovskite solar cell structure obtained in Example 7 is ITO / doped MoO3 / PTAA / MAPbI3 / PC. 60 BM / Ag.

[0165] Example 8 Preparation of ITO electrodes: Same as Example 1.

[0166] Preparation of the second hole transport layer: A precursor solution was prepared by adding lithium carbonate to a 0.08 mol / L MoO3 colloidal aqueous solution, wherein the concentration of lithium carbonate was 6%. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300 °C for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0167] Preparation of the first hole transport layer: NiO with a concentration of 3wt% was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm. x The nanocolloid aqueous solution was then heated at 300°C for 60 min on a constant temperature hot stage to obtain a first hole transport layer with a thickness of 15 nm.

[0168] Preparation of light-absorbing layer: Same as Example 1.

[0169] Fabrication of electron transport layer: Same as Example 1.

[0170] Preparation of Ag electrode: Same as Example 1.

[0171] The final perovskite solar cell structure obtained in Example 8 is ITO / doped MoO3 / NiO. x / MAPbI3 / PC 60 BM / Ag.

[0172] Example 9 Preparation of ITO electrodes: Same as Example 1.

[0173] Preparation of the second hole transport layer: A precursor solution was prepared by adding CoCl2 to a Cu2O colloidal aqueous solution with a concentration of 0.08 mol / L, wherein the concentration of CoCl2 was 10%. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300℃ for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0174] Preparation of the first hole transport layer: A PTAA toluene solution with a concentration of 2 mg / mL was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm, and then heated at 100 °C for 10 min on a constant temperature hot plate to obtain a first hole transport layer with a thickness of 15 nm.

[0175] Preparation of light-absorbing layer: Same as Example 1.

[0176] Fabrication of electron transport layer: Same as Example 1.

[0177] Preparation of Ag electrode: Same as Example 1.

[0178] The final perovskite solar cell structure obtained in Example 9 is ITO / doped Cu2O / PTAA / MAPbI3 / PC. 60 BM / Ag.

[0179] Example 10 Preparation of ITO electrodes: Same as Example 1.

[0180] Preparation of the second hole transport layer: A precursor solution was prepared by adding CoCl2 to a Cu2O colloidal aqueous solution with a concentration of 0.08 mol / L, wherein the concentration of CoCl2 was 20%. The precursor solution was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 300℃ for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0181] Preparation of the first hole transport layer: NiO with a concentration of 3wt% was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm. x The nanocolloid aqueous solution was then heated at 300°C for 60 min on a constant temperature hot stage to obtain a first hole transport layer with a thickness of 15 nm.

[0182] Preparation of light-absorbing layer: Same as Example 1.

[0183] Fabrication of electron transport layer: Same as Example 1.

[0184] Preparation of Ag electrode: Same as Example 1.

[0185] The final perovskite solar cell structure obtained in Example 10 is ITO / doped Cu2O / NiO. x / MAPbI3 / PC 60 BM / Ag.

[0186] Comparative Example 1 Preparation of ITO electrodes: Same as Example 1.

[0187] Preparation of hole transport layer NiO with a concentration of 6wt% was spin-coated onto the obtained ITO glass substrate at a speed of 4000 rpm to 6000 rpm. xA 25 nm thick hole transport layer was obtained by heating a CuI-mixed chlorobenzene solution, wherein the mass ratio of nickel oxide to CuI was 1:1, and then heating it at 300 °C for 60 min on a constant temperature hot stage.

[0188] Preparation of light-absorbing layer: Same as Example 1.

[0189] Fabrication of electron transport layer: Same as Example 1.

[0190] Preparation of Ag electrode: Same as Example 1.

[0191] The final perovskite solar cell structure obtained in Comparative Example 1 is ITO / NiO. x +CuI / MAPbI3 / PC 60 BM / Ag.

[0192] Comparative Example 2 Preparation of ITO electrodes: Same as Example 1.

[0193] Preparation of hole transport layer: A PTAA-CuI mixed chlorobenzene solution with a concentration of 2 mg / mL was spin-coated onto the obtained ITO glass substrate at a speed of 4000 rpm to 6000 rpm. The mass ratio of PTAA to CuI was 1:1. The substrate was then heated at 100 °C for 15 min on a constant temperature hot stage to obtain a hole transport layer with a thickness of 25 nm.

[0194] Preparation of light-absorbing layer: Same as Example 1.

[0195] Fabrication of electron transport layer: Same as Example 1.

[0196] Preparation of Ag electrode: Same as Example 1.

[0197] The final perovskite solar cell structure obtained in Comparative Example 2 is ITO / PTAA+CuI / MAPbI3 / PC. 60 BM / Ag.

[0198] Comparative Example 3 Preparation of ITO electrodes: Same as Example 1.

[0199] Preparation of the second hole transport layer: A solution of tri(isopropoxy)vanadium oxide in isopropanol was spin-coated onto the obtained ITO glass substrate at a speed of 5000 rpm to 6500 rpm, and then heated at 120 °C for 15 min on a constant temperature hot stage to obtain a second hole transport layer with a thickness of 10 nm.

[0200] Preparation of the first hole transport layer: NiO with a concentration of 3wt% was spin-coated onto the obtained second hole transport layer at a speed of 4000 rpm to 6000 rpm. x The nanocolloid aqueous solution was then heated at 300°C for 60 min on a constant temperature hot stage to obtain a first hole transport layer with a thickness of 15 nm.

[0201] Preparation of light-absorbing layer: Same as Example 1.

[0202] Fabrication of electron transport layer: Same as Example 1.

[0203] Preparation of Ag electrode: Same as Example 1.

[0204] The final perovskite solar cell structure obtained in Comparative Example 3 is ITO / V2O5 / NiO. x / MAPbI3 / PC 60 BM / Ag.

[0205] Test section The band distributions of the hole transport layer and the light-absorbing layer were measured using an Escalab 250Xi X-ray photoelectron spectroscopy (XPS) instrument (from Thermo Scientific) at room temperature and pressure. The results are shown in Table 1.

[0206] Table 2 presents the test results of open-circuit voltage Voc, short-circuit current density Jsc, fill factor, and power conversion efficiency of the perovskite solar cells prepared in Examples 1-10 and Comparative Examples 1-3 under standard simulated sunlight irradiation (AM1.5G).

[0207] Table 1 Table 2 As can be seen from the test results in Table 2, compared with Comparative Examples 1 and 2, the perovskite solar cells prepared in Examples 1-10 have higher open-circuit voltage Voc, short-circuit current density Jsc, fill factor, and power conversion efficiency.

[0208] The test results in Table 2 also show that Comparative Example 3 used V2O5 as the second hole transport material, but the performance of the prepared perovskite solar cell was worse than that of Examples 1-10. Possible reasons include: V2O5 is slightly soluble in water at room temperature and has a certain degree of hygroscopicity; furthermore, V2O5 is a strong oxidizing agent, and in the absence of encapsulation, it is easily consumed by reducing agents in the environment, forming powder or mesoporous states, thus introducing additional water and oxygen from the environment into the perovskite solar cell, and therefore failing to effectively isolate water and oxygen. In addition, the lattice matching degree between V2O5 and nickel oxide is not ideal, resulting in poor protection and passivation of the first hole transport layer. Therefore, the interfacial impedance and defect density between the first and second hole transport layers are high, affecting hole extraction and transport.

[0209] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A perovskite solar cell, comprising: First electrode; Second electrode; as well as The light-absorbing layer located between the first electrode and the second electrode. in, One of the first electrode and the second electrode is a transparent electrode, or both of them are transparent electrodes. The perovskite solar cell further includes a first hole transport layer and a second hole transport layer, wherein the first hole transport layer is located between the second hole transport layer and the light-absorbing layer, and the second hole transport layer is located between the first electrode and the light-absorbing layer, or the second hole transport layer is located between the second electrode and the light-absorbing layer. The first hole transport material of the first hole transport layer is selected from PTAA, nickel oxide doped with a first doping element, or undoped. The second hole transport material of the second hole transport layer includes at least one of a P-type transition metal oxide semiconductor material and a P-type transition metal halide semiconductor material that can isolate water and oxygen.

2. The perovskite solar cell according to claim 1, wherein the difference ΔVBM1 between the second hole transport layer and the top valence band energy level of the first hole transport layer is -1.0eV to 1.0eV, and optionally -0.3eV to 0.3eV.

3. The perovskite solar cell according to claim 1 or 2, wherein the first doping element comprises at least one selected from alkali metals, alkaline earth metals, transition metals, and halogens. Optionally, the alkali metal element includes at least one selected from Li, Na, K, Rb, and Cs. Optionally, the alkaline earth metal element includes at least one selected from Be, Mg, Ca, Sr, and Ba. Optionally, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au. Optionally, the halogen element includes at least one of F, Cl, Br, and I.

4. The perovskite solar cell according to any one of claims 1-3, wherein, Based on the total mass of the first hole transport material, the mass percentage of the first dopant element is ≤20%, and optionally 5%~15%.

5. The perovskite solar cell according to any one of claims 1-4, wherein, The second hole transport material includes at least one of the following materials, either doped or undoped by a second doping element: MoO3, CuO, Cu2O, CuI, NiMgLiO, CuGaO2, CuGrO2, and CoO. Optionally, the second hole transport material includes at least one of the following materials that are doped or undoped by the second doping element: MoO3, CuI, and NiMgLiO.

6. The perovskite solar cell according to claim 5, wherein, The second doping element includes at least one of the following: alkali metal, alkaline earth metal, transition metal, metal-poor element, metalloid, halogen, nonmetal, ionic liquid, carboxylic acid, phosphoric acid, carbon derivative, self-assembled monomer, and polymer. Optionally, the alkali metal element includes at least one selected from Li, Na, K, Rb, and Cs. Optionally, the alkaline earth metal element includes at least one selected from Be, Mg, Ca, Sr, and Ba. Optionally, the transition metal element includes at least one selected from Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au. Optionally, the metal-poor element includes at least one selected from Al, Ga, In, Sn, Tl, Pb, and Bi. Optionally, the metalloid element includes at least one selected from B, Si, Ge, As, Sb, and Te. Optionally, the halogen element includes at least one selected from F, Cl, Br, and I. Optionally, the nonmetallic element includes at least one of P, S, and Se. Optionally, the ionic liquid comprises at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, NH4Cl, (NH4)2S, tetramethylammonium hydroxide aqueous solution, and trifluoroethanol. Optionally, the carboxylic acid includes at least one selected from ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 4-imidazolium acetate hydrochloride, and acetic acid. Optionally, the carbon derivatives include carbon quantum dots, carbon nanotubes, graphene, and C. 60 g-C3N4, C9, NPC 60 -OH, DPC 60 At least one of them, Optionally, the self-assembled monomolecule includes at least one selected from 2-phenylethylamine hydroiodate, N,N-diethylaniline, 9,9-bis(4-aminophenyl)fluorene, 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane, and glycine. Optionally, the polymer includes at least one of styrene, polyethyleneimine, polyethylene oxide, and tris(N,N-tetramethylene)phosphoramide.

7. The perovskite solar cell according to claim 5 or 6, wherein, Based on the total mass of the second hole transport material, the mass percentage of the second dopant element is ≤30%, optionally 5%~25%.

8. The perovskite solar cell according to any one of claims 5-7, wherein, The second hole transport material includes at least one of CuI, MoO3, NiMgLiO, K-doped CuI, K-doped MoO3, Li-doped MoO3, K-doped NiMgLiO, and Co-doped Cu2O.

9. The perovskite solar cell according to any one of claims 1-8, wherein, The energy difference ΔVBM2 between the top valence band of the first hole transport layer and the light-absorbing layer is -1.0eV to 1.0eV, and optionally -0.3eV to 0.3eV.

10. The perovskite solar cell according to any one of claims 1-9, wherein, The difference between the conduction band top level of the second hole transport layer and the light-absorbing layer is ≥0.5 eV, and / or, The difference between the top conduction band energy level of the first hole transport layer and the light-absorbing layer is ≥0.5eV.

11. The perovskite solar cell according to any one of claims 1-10, wherein, The difference between the Fermi level and the top valence band level of the second hole transport layer is ≤1.5 eV, and / or, The difference between the Fermi level and the top valence band level of the first hole transport layer is ≤1.5 eV.

12. The perovskite solar cell according to any one of claims 1-11, wherein, The band gap of the second hole transport layer is ≥1.5eV.

13. The perovskite solar cell according to any one of claims 1-12, wherein, The thickness of the second hole transport layer is 1 nm to 300 nm, optionally 1 nm to 100 nm, and / or The thickness of the first hole transport layer is 5nm~1000nm, optionally 10nm~200nm. Optionally, the ratio of the thickness of the first hole transport layer to the thickness of the second hole transport layer is 1:1 to 10:

1.

14. The perovskite solar cell according to any one of claims 1-13, wherein, The light-absorbing layer comprises a perovskite material; and / or, The thickness of the light-absorbing layer is 50 nm to 2000 nm.

15. The perovskite solar cell according to any one of claims 1-14, wherein, The transparent electrode is an FTO electrode, an ITO electrode, an AZO electrode, a BZO electrode, or an IZO electrode. Optionally, the transparent electrode is an FTO electrode or an ITO electrode.

16. The perovskite solar cell according to any one of claims 1-15, wherein, One of the first electrode and the second electrode is a metal electrode or a conductive carbon electrode. Optionally, the metal electrode is selected from one or more of the following: gold electrode, silver electrode, aluminum electrode, and copper electrode.

17. The perovskite solar cell according to any one of claims 1-16, wherein, The perovskite solar cell further includes an electron transport layer located between the light-absorbing layer and the second electrode or the first electrode, and the light-absorbing layer located between the first hole transport layer and the electron transport layer.

18. The perovskite solar cell according to claim 17, wherein, The perovskite solar cell comprises a first electrode, a second hole transport layer, a first hole transport layer, a light-absorbing layer, an electron transport layer, and a second electrode arranged sequentially. Alternatively, the perovskite solar cell may include a first electrode, an electron transport layer, a light-absorbing layer, a first hole transport layer, a second hole transport layer, and a second electrode arranged sequentially.

19. A photovoltaic module comprising a perovskite solar cell according to any one of claims 1-18.

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