Perovskite solar cells and photovoltaic modules

Abstract

The present application provides a perovskite solar cell and a photovoltaic module. The perovskite solar cell includes: a perovskite layer including a first surface and a second surface opposite to each other along its thickness direction; a hole transport layer disposed on the first surface; and an electron transport layer disposed on the second surface. The electron transport layer includes at least two sub-layers, the electron transport layer includes a doping material, and the bottom energy level of the conduction band of each sub-layer is lower than the bottom energy level of the conduction band of the hole transport layer; the top energy level of the valence band of each sub-layer is lower than the top energy level of the valence band of the hole transport layer. The energy level structure of the perovskite solar cell according to the embodiments of the present application can ensure the efficient transport of carriers and improve the photoelectric conversion efficiency of the perovskite solar cell.

Description

Technical Field

[0001] This application belongs to the technical field of solar cells, and particularly relates to a perovskite solar cell and a photovoltaic module. Background Art

[0002] A perovskite solar cell is a solar cell that uses an organometallic halide perovskite material as a light-absorbing layer, and has excellent optoelectronic properties and a simple preparation method, bringing new space and hope for photovoltaic power generation.

[0003] In the production process of perovskite solar cells, how to further improve their photoelectric conversion efficiency is an urgent problem to be solved. Summary of the Invention

[0004] Embodiments of this application provide a perovskite solar cell and a photovoltaic module, which can improve the photoelectric conversion efficiency of the perovskite solar cell.

[0005] An embodiment of the first aspect of this application provides a perovskite solar cell, which includes a perovskite layer, a hole transport layer, and an electron transport layer. The perovskite layer includes a first surface and a second surface that are opposite to each other along its thickness direction. The hole transport layer is disposed on the first surface. The electron transport layer is disposed on the second surface, and the electron transport layer includes at least two sub-layers. The electron transport layer includes a doping material, and the bottom energy level of the conduction band of each sub-layer is less than the bottom energy level of the conduction band of the hole transport layer; the top energy level of the valence band of each sub-layer is less than the top energy level of the valence band of the hole transport layer.

[0006] In the perovskite solar cell of this application, by doping a doping material in the electron transport layer to regulate the energy level structure, the formation of the built-in electric field in the perovskite solar cell can be ensured, and the efficient transport of carriers can be ensured. At the same time, the difference in the bottom energy level of the conduction band can ensure the unidirectional transport of electrons, and the difference in the top energy level of the valence band can ensure the unidirectional transport of holes, which can effectively improve the photoelectric conversion efficiency of the perovskite solar cell. At the same time, the perovskite solar cell of this application can inhibit the migration of halogens in the perovskite layer, improve the structural stability of the perovskite solar cell, and thus further improve the photoelectric conversion efficiency of the perovskite solar cell.

[0007] In any implementation manner, the difference between the bottom energy level of the conduction band of the sub-layer of the electron transport layer close to the second surface and the bottom energy level of the conduction band of the perovskite layer is -1.0 eV to 1.0 eV. Optionally, the difference between the bottom energy level of the conduction band of the sub-layer and the bottom energy level of the conduction band of the perovskite layer is -0.3 eV to 0.3 eV; the above numerical range can improve the transport efficiency of electrons.

[0008] In any implementation manner, the top energy level of the valence band of the sub-layer of the electron transport layer close to the second surface is less than the top energy level of the valence band of the perovskite layer, which can avoid the recombination of holes and electrons to a certain extent and reduce the current of the perovskite solar cell.

[0009] In any embodiment, the difference between the Fermi level of the sub-layer of the electron transport layer near the second surface and the perovskite layer is ≤ 1.5 eV. The above difference range can ensure that the electron transport layer is of electron-conductive type and improve the electron transport efficiency.

[0010] In any embodiment, the difference between the bottom energy level of the conduction band and the Fermi level of the sub-layer of the electron transport layer near the second surface is ≤ 1.5 eV. The above difference range can reduce the unnecessary band bending between the electron transport layer and the perovskite layer, improve the carrier transport rate, and thus improve the photoelectric conversion efficiency of the perovskite solar cell.

[0011] In any embodiment, the difference between the bottom energy level of the conduction band and the top energy level of the valence band of the sub-layer of the electron transport layer near the second surface is ≥ 1.5 eV. The sub-layer satisfying the above numerical range has a relatively large band gap, can filter ultraviolet light, and avoids damage to the perovskite layer by ultraviolet light.

[0012] In any embodiment, the electron transport layer includes a first sub-layer, a second sub-layer, and a third sub-layer that are sequentially stacked in a direction away from the second surface. Among them, the first sub-layer is a tin oxide layer including a first doping material, and the first doping material includes alkali metals, alkaline earth metals, transition metals, poor metals, metalloids, non-metallic elements, ionic liquids, carboxylic acids, phosphoric acids, carbon derivatives, self-assembled monolayers, or organic high molecular polymers; the electron transport layer including three sub-layers can flexibly regulate the energy levels of each layer, which is beneficial to improving the extraction efficiency and transport efficiency of carriers.

[0013] In any embodiment, the alkali metal includes at least one of Li, K, Na, Rb, and Cs.

[0014] The alkaline earth metal includes at least one of Be, Sr, and Ba.

[0015] The transition metal includes at least one of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au.

[0016] The poor metal includes at least one of Al, Ga, In, Sn, Tl, Pb, and Bi.

[0017] The metalloid includes at least one of B, Si, Ge, As, Sb, and Te.

[0018] The non-metallic element includes at least one of F, Cl, Br, I, P, S, and Se.

[0019] The ionic liquid includes at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, ammonium chloride, ammonium sulfide, tetramethylammonium hydroxide, and 2,2,2-trifluoroethanol.

[0020] The carboxylic acid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 4-imidazoleacetic acid hydrochloride, and acetic acid.

[0021] The carbon derivative includes at least one of carbon quantum dots, carbon nanotubes, graphene, C60, C60 derivatives, graphitic carbon nitride, and C9.

[0022] The self-assembled monolayer includes at least one of 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane, and glycine.

[0023] The organic polymer includes at least one of polystyrene, polyethoxyethyleneimine, polyethylene oxide, and triphenylphosphine oxide.

[0024] The above-mentioned first doping material can effectively improve the energy level of the electron transport layer and regulate the energy level structure of the perovskite solar cell.

[0025] In any embodiment, the second sublayer includes an imide compound layer, a quinone compound layer, a fullerene layer, a perovskite-type oxide layer, a fluoride layer, or an oxide layer. The first sublayer and the second sublayer cooperate with each other to effectively improve the energy level structure of the electron transport layer.

[0026] In some embodiments, the imide compound layer includes an imide compound or a derivative of an imide compound. The imide compound includes: phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide.

[0027] The quinone compound layer includes a quinone compound or a derivative of a quinone compound. The quinone compound includes benzoquinone, naphthoquinone, phenanthraquinone, or anthraquinone.

[0028] The perovskite-type oxide layer includes strontium titanate, calcium titanate, barium titanate, lithium titanate, iron titanate, nickel titanate, or cobalt titanate.

[0029] The fluoride layer includes lithium fluoride or calcium fluoride.

[0030] The oxide layer includes an oxide layer of the following elements: Ce, Mg, Si, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, or Cr.

[0031] The second sublayer made of the above materials can effectively improve the energy level structure of the electron transport layer.

[0032] In any embodiment, the third sub-layer includes a metal oxide layer or a metal oxide layer containing a second doping material, and the metal oxide layer includes a SnO2 layer, an In2O3 layer, a ZnO layer, a CdO layer, a NiO layer, a CdIn2O4 layer, a Cd2SnO4 layer, a Zn2SnO4 layer, a MgIn2O4 layer, a ZnIn2O4 layer, a CoIn3O6 layer, a ZnV2O6 layer, a CuAlO2 layer or a CuGaO2 layer. The first sub-layer, the second sub-layer and the third sub-layer cooperate with each other to effectively improve the energy level structure of the electron transport layer.

[0033] In any embodiment, the SnO2 layer includes a second doping material, and the elements of the second doping material include at least one of F, Sb, P, As, Te and Cl.

[0034] The In2O3 layer includes a second doping material, and the elements of the second doping material include at least one of W, Mn, Zr, Ti, Sb, F and Ag.

[0035] The ZnO layer includes a second doping material, and the elements of the second doping material include at least one of Ga, In, F, N, B and Al.

[0036] The third sub-layer containing the above-mentioned second doping material can effectively improve the energy level structure of the electron transport layer.

[0037] The second aspect of the present application provides a photovoltaic module, including the perovskite solar cell according to any embodiment of the first aspect of the present application. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the drawings without creative efforts.

[0039] Figure 1 It is a schematic structural diagram of a perovskite solar cell provided by some embodiments of the present application;

[0040] Figure 2 It is a schematic structural diagram of a perovskite solar cell provided by some other embodiments of the present application;

[0041] Figure 3 It is a schematic structural diagram of a perovskite solar cell provided by some other embodiments of the present application.

[0042] In the drawings, the drawings are not necessarily drawn to actual scale.

[0043] Among them, the reference numerals in the drawings:

[0044] X, thickness direction;

[0045] 10, perovskite layer; 10a, first surface; 10b, second surface;

[0046] 20, hole transport layer;

[0047] 30, electron transport layer; 31, first sub-layer; 32, second sub-layer; 33, third sub-layer;

[0048] 40, first electrode; 50, second electrode. Detailed implementation manners

[0049] Hereinafter, embodiments of the perovskite solar cell and photovoltaic module of the present application are specifically disclosed with appropriate reference to the drawings. However, there may be cases where unnecessary details are omitted. For example, there may be cases where details of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0050] The "ranges" disclosed in the present application are defined in the form of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include or exclude the end values and can be combined arbitrarily, 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, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when a certain parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] If there is no special instruction, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0052] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0053] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0054] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application mean open-ended, and can also be closed-ended. For example, "comprising" and "including" can mean that other components not listed can also be included, or can also mean that only the listed components are included.

[0055] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0056] The perovskite solar cell includes a perovskite layer, a hole transport layer, an electron transport layer, and electrodes. The working process of the perovskite cell mainly includes: the generation and separation of excitons, the transport of free carriers, the collection of carriers, and the generation of current. The specific process is as follows: In the perovskite solar cell, sunlight is absorbed by the perovskite layer. The perovskite layer absorbs photons to generate excitons. Due to the low Coulomb force binding in the perovskite layer, the excitons are then separated into free electrons and holes. The separated free carriers are transported in the perovskite layer and transmitted out through the transport layer. The electron transport layer plays a role in transporting electrons and blocking holes, and the hole transport layer plays a role in transporting holes and blocking electrons. The electrons and holes transmitted out through the transport layer are respectively collected by the electrodes to form current and voltage.

[0057] In addition, during the working process of the perovskite cell, carriers will recombine at the interface between the perovskite layer and the transport layer, and the recombination of carriers will seriously affect the efficiency of the perovskite solar cell.

[0058] In order to improve the photoelectric conversion efficiency of perovskite solar cells, the inventors improved perovskite solar cells by regulating the energy level structure through a bulk doping method. Regulating the energy level structure can reduce the recombination of photo-generated carriers to a certain extent, improve the extraction and transport efficiency of electrons, and thus increase the open-circuit voltage and current.

[0059] [Perovskite solar cell]

[0060] An embodiment of the first aspect of the present application provides a perovskite solar cell.

[0061] Figure 1 The structural schematic diagram of the perovskite solar cell provided by some embodiments of the present application is shown. As Figure 1 shown, the perovskite solar cell includes a perovskite layer 10, a hole transport layer 20, and an electron transport layer 30. The perovskite layer 10 includes a first surface 10a and a second surface 10b that are opposite to each other along its thickness direction X. The hole transport layer 20 is disposed on the first surface 10a. The electron transport layer 30 is disposed on the second surface 10b. The electron transport layer 30 includes at least two sub-layers 30a. The electron transport layer 30 includes a doping material. The bottom energy level of the conduction band of each sub-layer 30a is less than the bottom energy level of the conduction band of the hole transport layer 20, and the bottom energy level of the conduction band of each sub-layer 30a is less than the top energy level of the valence band of the hole transport layer 20.

[0062] For the perovskite solar cell according to the embodiment of the present application, the energy level structure is regulated by doping a doping material in the electron transport layer 30, so that the bottom energy level of the conduction band of each sub-layer 30a in the electron transport layer 30 is less than the bottom energy level of the conduction band of the hole transport layer 20, the top energy level of the valence band of each sub-layer 30a is less than the top energy level of the valence band of the hole transport layer 20, and there is an energy level difference between the energy levels of each sub-layer 30a and the energy levels of the hole transport layer 20. The existence of the energy level difference can ensure the formation of the built-in electric field in the perovskite solar cell and ensure the efficient transport of carriers. At the same time, the energy level difference at the bottom of the conduction band can ensure the unidirectional transport of electrons, and the energy level difference at the top of the valence band can ensure the unidirectional transport of holes, which can effectively improve the photoelectric conversion efficiency of the perovskite solar cell. At the same time, the embodiment of the present application can inhibit the migration of halogens in the perovskite layer 10 and improve the structural stability of the perovskite solar cell.

[0063] The large energy level difference between each sub-layer 30a and the hole transport layer 20 can further ensure the formation of the built-in electric field in the perovskite solar cell and ensure the efficient transport of carriers.

[0064] In some embodiments, the energy difference between the bottom energy level of the conduction band of the perovskite layer 10 and the sub-layer 30a of the electron transport layer 30 near the second surface 10b is -1.0 eV to 1.0 eV. Optionally, the energy difference between the bottom energy level of the conduction band of the perovskite layer 10 and the sub-layer 30a of the electron transport layer 30 near the second surface 10b is -0.3 eV to 0.3 eV. The energy level difference between the sub-layer 30a of the electron transport layer 30 near the second surface 10b and the perovskite layer 10 satisfying the above numerical range can improve the electron transport efficiency. And the energy difference of the bottom energy level of the conduction band within the above range can reduce the recombination of photo-generated carriers and improve the open voltage and current.

[0065] In some embodiments, the top energy level of the valence band of the sub-layer 30a of the electron transport layer 30 near the second surface 10b is less than the top energy level of the valence band of the perovskite layer 10. The top energy level of the valence band of the sub-layer 30a of the electron transport layer 30 near the second surface 10b can more effectively block holes from the perovskite layer 10, and can to a certain extent avoid the recombination of holes and electrons, reducing the current of the perovskite solar cell.

[0066] In some embodiments, the energy difference between the sub-layer 30a of the electron transport layer 30 near the second surface 10b and the Fermi level of the perovskite layer 10 is ≤ 1.5 eV. The above difference range can ensure that the electron transport layer 30 is of electron-conductive type and improve the electron transport efficiency.

[0067] Since severe band bending can form a barrier on the carrier transport channel, affecting the performance of the perovskite solar cell. In some embodiments, the energy difference between the bottom energy level of the conduction band and the Fermi level of the sub-layer 30a of the electron transport layer 30 near the second surface 10b is ≤ 1.5 eV. The above difference range can reduce the unnecessary band bending between the electron transport layer 30 and the perovskite layer 10, improve the carrier transport rate, and thus improve the photoelectric conversion efficiency of the perovskite solar cell.

[0068] In some embodiments, the energy difference between the bottom energy level of the conduction band and the top energy level of the valence band of the sub-layer 30a of the electron transport layer 30 near the second surface 10b is ≥ 1.5 eV. The sub-layer satisfying the above numerical range has a large band gap, can filter ultraviolet light, and avoids damage to the perovskite layer 10 by ultraviolet light.

[0069] [Electron transport layer]

[0070] As a transport layer, the electron transport layer 30 can effectively transport electrons, reduce the carrier recombination at the interface between the perovskite layer 10 and the electron transport layer 30, and improve the photoelectric conversion efficiency of the perovskite solar cell.

[0071] In the embodiments of the present application, the electron transport layer 30 includes at least two sub-layers 30a.

[0072] Exemplarily, the electron transport layer 30 includes two sub-layers 30a, namely a first sub-layer 31 and a second sub-layer 32; or the electron transport layer 30 includes three sub-layers 30a, namely a first sub-layer 31, a second sub-layer 32 and a third sub-layer 33; or the electron transport layer 30 includes four sub-layers, namely a first sub-layer 31, a second sub-layer 32, a third sub-layer 33 and a fourth sub-layer, and so on. The above description of the electron transport layer 30 is only an exemplary description and is not used to limit the specific number of layers of the electron transport layer 30.

[0073] Figure 2 FIG. shows a schematic structural diagram of a perovskite solar cell provided by some embodiments of the present application. As Figure 2 shown, in some embodiments, the electron transport layer 30 includes three sub-layers, namely a first sub-layer 31, a second sub-layer 32 and a third sub-layer 33. The first sub-layer 31, the second sub-layer 32 and the third sub-layer 33 are sequentially stacked in a direction away from the second surface 10b. The first sub-layer 31 is disposed close to the perovskite layer 10, the third sub-layer 33 is disposed away from the perovskite layer 10, and the second sub-layer 32 is located between the first sub-layer 31 and the third sub-layer 33. The electron transport layer 30 including three sub-layers can flexibly regulate the energy levels of each layer, which is beneficial to improving the extraction efficiency and transport efficiency of carriers.

[0074] The first sub-layer 31 is a tin oxide layer containing a first doping material. The first doping material includes alkali metals, alkaline earth metals, transition metals, poor metals, metalloids, non-metallic elements, ionic liquids, carboxylic acids, phosphoric acids, carbon derivatives, self-assembled monolayers or organic high molecular polymers. The tin oxide layer has good energy level alignment and high mobility itself, and can achieve efficient electron extraction and transport. By doping the first doping material in the first sub-layer 31, the first doping material can regulate the energy level of the first sub-layer 31, passivate the bulk defects of the material, improve the carrier concentration and mobility, and thus improve the photoelectric conversion efficiency of the perovskite solar cell.

[0075] By selecting the first doping material, the energy level of the electron transport layer 30 can be effectively improved, and the energy level structure of the perovskite cell can be adjusted. Next, specific examples of the first doping material will be given.

[0076] As some examples of alkali metals, the alkali metals include at least one of Li, K, Na, Rb and Cs.

[0077] As some examples of alkaline earth metals, the alkaline earth metals include at least one of Be, Sr and Ba.

[0078] Some examples of transition metals include at least one of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt, and Au.

[0079] Some examples of poor metals include at least one of Al, Ga, In, Sn, Tl, Pb, and Bi.

[0080] Some examples of metalloids include at least one of B, Si, Ge, As, Sb, and Te.

[0081] Some examples of non-metal elements include at least one of F, Cl, Br, I, P, S, and Se.

[0082] Some examples of ionic liquids include at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, ammonium chloride, ammonium sulfide, tetramethylammonium hydroxide, and 2,2,2-trifluoroethanol.

[0083] Some examples of carboxylic acids include at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 4-imidazoleacetic acid hydrochloride, and acetic acid.

[0084] Some examples of carbon derivatives include at least one of carbon quantum dots, carbon nanotubes, graphene, C60, C60 derivatives, graphitic carbon nitride, and C9.

[0085] Some examples of self-assembled monolayers include at least one of 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane, and glycine.

[0086] Some examples of organic high molecular polymers include at least one of polystyrene, polyethoxyethyleneimine, polyethylene oxide, and triphenylphosphine oxide.

[0087] The second sublayer 32 includes an imide compound layer, a quinone compound layer, a fullerene layer, a perovskite-type oxide layer, a fluoride layer, or an oxide layer. The first sublayer 31 and the second sublayer 32 cooperate with each other to effectively improve the energy level structure of the electron transport layer 30.

[0088] Some examples of the imide compound layer include an imide compound or a derivative of an imide compound, and the imide compound includes: phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide.

[0089] As some examples of quinone compounds, the quinone compound layer includes quinone compounds or derivatives of quinone compounds, and the quinone compounds include: benzoquinone, naphthoquinone, phenanthraquinone or anthraquinone.

[0090] As some examples of perovskite oxide layers, the perovskite oxide layers include strontium titanate, calcium titanate, barium titanate, lithium titanate, iron titanate, nickel titanate or cobalt titanate.

[0091] As some examples of fluoride layers, the fluoride layers include lithium fluoride or calcium fluoride.

[0092] As some examples of oxide layers, the oxide layers include oxide layers of the following elements: Ce, Mg, Si, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga or Cr.

[0093] The third sub-layer 33 includes a metal oxide layer or a metal oxide layer containing a second doping material. The metal oxide layer includes a SnO2 layer, an In2O3 layer, a ZnO layer, a CdO layer, a NiO layer, a CdIn2O4 layer, a Cd2SnO4 layer, a Zn2SnO4 layer, a MgIn2O4 layer, a ZnIn2O4 layer, a CoIn3O6 layer, a ZnV2O6 layer, a CuAlO2 layer or a CuGaO2 layer. The first sub-layer 31, the second sub-layer 32 and the third sub-layer 33 cooperate with each other and can effectively improve the energy level structure of the electron transport layer 30.

[0094] As some examples of the SnO2 layer, the SnO2 layer includes a second doping material, and the elements of the second doping material include at least one of F, Sb, P, As, Te and Cl.

[0095] As some examples of the In2O3 layer, the In2O3 layer includes a second doping material, and the elements of the second doping material include at least one of W, Mn, Zr, Ti, Sb, F and Ag.

[0096] As some examples of the ZnO layer, the ZnO layer includes a second doping material, and the elements of the second doping material include at least one of Ga, In, F, N, B and Al.

[0097] [Hole transport layer]

[0098] The hole transport layer 20, as a transport layer, can effectively transport holes, reduce the carrier recombination at the interface between the perovskite layer 10 and the hole transport layer 20, and improve the photoelectric conversion efficiency of the perovskite solar cell. The material of the hole transport layer 20 can be selected from conventional materials in the art and is not limited herein.

[0099] [Perovskite layer]

[0100] The perovskite layer 10 serves as a light absorption layer and can convert photons into holes and electrons. The material thereof can be selected from conventional materials in the art and is not limited herein.

[0101] The perovskite solar cell of the embodiment of the present application further includes a first electrode and a second electrode. At least one of the first electrode and the second electrode is a transparent electrode. As an example, the transparent electrode is an FTO conductive glass electrode.

[0102] Figure 3 The structural schematic diagram of the perovskite solar cell provided by some embodiments of the present application is shown, as Figure 3 shown, the perovskite solar cell includes a first electrode 40, a hole transport layer 20, a perovskite layer 10, an electron transport layer 30, and a second electrode 50 sequentially arranged along its thickness direction X. Among them, the electron transport layer 30 includes a first sub-layer 31, a second sub-layer 32, and a third sub-layer 33.

[0103] [Preparation method of perovskite solar cell]

[0104] The second aspect of the present application provides a preparation method of a perovskite solar cell for preparing the perovskite solar cell of the first aspect of the present application. The conduction band bottom energy level of each sub-layer of the electron transport layer of the prepared perovskite solar cell is less than the conduction band bottom energy level of the hole transport layer; the valence band top energy level of each sub-layer is less than the valence band top energy level of the hole transport layer.

[0105] [Photovoltaic module]

[0106] The third aspect of the present application further provides a photovoltaic module, including the perovskite solar cell of any embodiment of the first aspect of the present application, or the perovskite solar cell prepared by the method of the second aspect of the present application. The perovskite solar cell can be used as a power source of the photovoltaic module or as an energy storage unit of the photovoltaic module.

[0107] Example

[0108] The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present application are obvious to those skilled in the art. 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 according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0109] Examples 1 - 21

[0110] Preparation of FTO Conductive Glass Electrode

[0111] Take a set of FTO conductive glasses with a specification of 2.0 cm × 2.0 cm. The surface of the FTO conductive glasses is cleaned twice with acetone and isopropanol in sequence, immersed in deionized water and ultrasonically treated for 10 min, then dried in a blast drying oven and placed in a glove box (N2 atmosphere).

[0112] Preparation of electron transport layer, which includes a first sub - layer and a second sub - layer.

[0113] Preparation of the second sub - layer

[0114] Add a second doping material to the second host material to form a second mixture.

[0115] Spin - coat the second mixture on the FTO conductive glass electrode at a speed of 4000 rpm to 6500 rpm, and heat it at a constant temperature on a constant - temperature hot stage. The coating thickness is 10 - 30 nm.

[0116] Preparation of the first sub - layer

[0117] Add a first doping material to the first host material to form a first mixture.

[0118] Spin - coat the first mixture on the second sub - layer at a speed of 4000 rpm to 6500 rpm, and heat it at a constant temperature on a constant - temperature hot stage. The coating thickness is 10 - 30 nm.

[0119] Preparation of perovskite layer

[0120] Spin - coat the M solution with a concentration of 1.5 mol / L on the obtained first sub - layer at a speed of 3000 rpm to 4500 rpm. Then move the obtained product to a constant - temperature hot stage, heat it at 100 °C for 30 min, and after cooling to room temperature, form a perovskite layer with a thickness of 500 nm.

[0121] Preparation of hole transport layer

[0122] Continue to spin - coat the ethyl acetate solution of copper oxide with a concentration of 0.1 mol / L on the perovskite layer at a speed of 4500 rpm to 6000 rpm, heat it at 100 °C for 60 min, and the thickness is 30 - 60 nm.

[0123] Preparation of Ag electrode

[0124] Put the aforementioned sample into a vacuum coating machine. Under a vacuum condition of 5×10 -4 Pa, evaporate and deposit an Ag electrode on the surface of the obtained hole - transporting layer. The thickness of the Ag electrode is 80 nm.

[0125] The types of related substances in Examples 1 to 21 are shown in Table 1:

[0126] Table 1

[0127]

[0128]

[0129] In Table 1, the aqueous solution of SnO2 nanocolloid means that SnO2 particles are distributed in the aqueous solution with a particle size of 10 - 50 nm. Perylene diimide is Perylene tetracarboxylic acid diimide, abbreviated as PDI. FAMAPbI3 is formamidinium methylammonium lead iodide perovskite. MAPbI3 is methylammonium lead iodide perovskite. MAPbI2Br is methylammonium lead iodide bromide perovskite. FA 0.85 Cs 0.15 PbI3 is formamidinium cesium lead iodide perovskite. FA 0.9 Cs 0.1 PbI3 is formamidinium cesium lead iodide perovskite. FA 0.9 MA 0.1 PbI3 is formamidinium methylammonium lead iodide perovskite. MAPbBr3 is methylammonium lead bromide perovskite. DMF refers to N,N - dimethylformamide, and its English name is N,N - Dimethylformamide.

[0130] Examples 22 - 40

[0131] Preparation of FTO Conductive Glass Electrode

[0132] Take a set of FTO conductive glasses with a specification of 2.0 cm × 2.0 cm. The surface of the FTO conductive glass is cleaned twice with acetone and isopropanol in sequence, immersed in deionized water and ultrasonically treated for 10 min, then dried in a blast drying oven and placed in a glove box (N2 atmosphere).

[0133] Preparation of a layer including a first sub - layer, a second sub - layer and a third sub - layer

[0134] Preparation of the third sub - layer

[0135] Dope a third doping material in the third host material to form a third mixture;

[0136] Magnetron sputter the third mixture (target) on the FTO conductive glass electrode. Among them, the sputtering power is 1000 W, the ratio of argon to oxygen is 1:1, the pressure is 0.25 Pa, the sputtering thickness is 10 - 30 nm, and it is heated at 150 °C for 20 min.

[0137] Preparation of the second sub - layer

[0138] Add a second doping material to the second host material to form a second mixture,

[0139] Spin-coat the second mixture on the FTO conductive glass electrode at a speed of 4000 rpm to 6500 rpm, and heat it on a constant-temperature hot stage. The coating thickness is 10 to 30 nm.

[0140] Preparation of the first sub - layer

[0141] Add the first doping material to the first host material to form the first mixture.

[0142] Spin-coat the first mixture on the second sub-layer at a speed of 4000 rpm to 6500 rpm, and heat it on a constant-temperature hot stage. The coating thickness is 10 to 30 nm.

[0143] Preparation of perovskite layer

[0144] Spin-coat the DMF solution of FA 0.9 MA 0.1 PbI3 with a concentration of 1.5 mol / L on the obtained electron transport layer at a speed of 3000 rpm to 4500 rpm, then move it to a constant-temperature hot stage and heat it at 100 °C for 30 min. After cooling to room temperature, a perovskite layer with a thickness of 500 nm is formed.

[0145] Preparation of hole transport layer

[0146] Continue to spin-coat the ethyl acetate solution of copper oxide with a concentration of 0.1 mol / L on the perovskite layer at a speed of 4500 rpm to 6000 rpm, and heat it at 100 °C for 60 min. The thickness is 30 to 60 nm.

[0147] Preparation of Ag electrode

[0148] Put the aforementioned sample into a vacuum coating machine, and evaporate an Ag electrode on the surface of the hole transport layer under a vacuum condition of 5×10 -4 Pa. The thickness of the Ag electrode is 80 nm.

[0149] The types of related substances in Examples 22 to 40 are shown in Table 2:

[0150] Table 2

[0151]

[0152]

[0153] Comparative Examples 1 - 7

[0154] Preparation of FTO Conductive Glass Electrode

[0155] Take a set of FTO conductive glasses with a specification of 2.0 cm × 2.0 cm. The surface of the FTO conductive glasses is cleaned twice with acetone and isopropanol in sequence, immersed in deionized water for ultrasonic treatment for 10 min, dried in a blast drying oven, and then placed in a glove box (N2 atmosphere).

[0156] Preparation of electron transport layer, which includes a first sub - layer and a second sub - layer

[0157] Preparation of the second sub - layer

[0158] Spin-coat the F solution with a concentration on the FTO conductive glass electrode at a speed of 4000 rpm to 6500 rpm, heat it at 100 °C for 10 min, and the thickness is 10 - 30 nm. The specific types of the F solution are shown in Table 5.

[0159] Preparation of the first sub - layer

[0160] Spin-coat the 3 wt.% SnO2 nano-colloidal aqueous solution on the second sub-layer at 4000 rpm to 6500 rpm, and then heat it on a constant temperature hot stage at 150 °C for 15 min, and the thickness is 30 - 60 nm.

[0161] Preparation of perovskite layer

[0162] Spin-coat the M solution with a concentration of 1.5 mol / L on the first sub-layer at a speed of 3000 rpm to 4500 rpm, then move it to a constant temperature hot stage, heat it at 100 °C for 30 min, and after cooling to room temperature, form a perovskite layer with a thickness of 500 nm. The specific types of the M solution are shown in Table 5.

[0163] Preparation of hole transport layer

[0164] Spin-coat the S solution with a concentration of 0.1 mol / L on the perovskite layer at a speed of 4500 rpm to 6000 rpm, heat it at 100 °C for 60 min, and the thickness is 30 - 60 nm. The specific types of the S solution are shown in Table 3.

[0165] Table 3

[0166]

[0167] Among them, H101 in Table 3 represents triphenylene-based triphenylamine, CzPAF-SBF represents N-(4-aniline)carbazole-spirobifluorene, and Z101 represents 4-((E)-4-(bis(4-((E)-4-(dibutylamino)styryl)phenyl)amino)styryl)-N-(4-((E)((E)-4-(dibutylamino)styryl)phenyl)amino)phenyl)-N-phenylaniline.

[0168] Preparation of Ag electrode

[0169] Put the aforementioned sample into a vacuum coating machine, and evaporate an Ag electrode on the surface of the hole transport layer under a vacuum condition of 5×10 -4 Pa. The thickness of the Ag electrode is 80 nm.

[0170] Performance Test Method for Perovskite Solar Cells

[0171] 1. Energy band distribution testing method

[0172] Use an ultraviolet photoelectron spectrometer (UPS) and an X-ray photoelectron spectrometer (XPS) to test the energy band distributions of each sub-layer, the hole transport layer, and the perovskite absorption layer in the obtained electron transport layer. The test conditions are normal temperature, normal pressure, and atmospheric environment, and a He I lamp (21.2 eV) is used as the light source. Exemplarily, the models of the UPS and XPS equipment are Escalab 250Xi (Thermo Scientific).

[0173] 2. Power conversion efficiency testing method

[0174] The energy conversion efficiency is obtained through voltage-current characteristic testing. The intensity of the simulated solar light source is standard AM1.5G, and the test conditions are normal temperature, normal pressure, and atmospheric environment. Exemplarily, the model of the test equipment is OptoSolar IVS-KA5000.

[0175] Performance Test Results of Perovskite Solar Cells

[0176] It should be noted that in the following description, CBM represents the bottom energy level of the conduction band, VBM represents the top energy level of the valence band, and FLP represents the Fermi energy level difference. Among them, CBM1 represents the bottom energy level of the conduction band of the first sub-layer, CBM2 represents the bottom energy level of the conduction band of the second sub-layer, CBM3 represents the bottom energy level of the conduction band of the third sub-layer, CBM4 represents the bottom energy level of the conduction band of the hole transport layer, and CBM5 represents the bottom energy level of the conduction band of the perovskite layer.

[0177] 1. The performance test results of Examples 1 to 8 and Comparative Examples 1 to 4 are shown in Table 4.

[0178] Table 4

[0179]

[0180] As can be seen from Table 4, compared with Comparative Examples 1 to 4, the bottom energy levels of the conduction bands of each sub-layer of the perovskite solar cells in Examples 1 to 8 are less than the bottom energy level of the conduction band of the hole transport layer, the electron transport efficiency of the first sub-layer is relatively high, the top energy levels of the valence bands of each sub-layer are less than the top energy level of the valence band of the hole transport layer, and the electron transport efficiency of the electron transport layer is relatively high, which is beneficial to improving the power conversion efficiency of the perovskite solar cells.

[0181] 2. The performance test results of Examples 9 to 14 and Comparative Examples 5 to 7 are shown in Tables 5 and 6.

[0182] Table 5

[0183]

[0184] Table 6

[0185]

[0186] As can be seen from Tables 5 and 6, compared with Comparative Examples 5 to 7, the energy level difference between the conduction band bottom of the first sub-layer and the perovskite layer of the perovskite solar cells in Examples 9 to 14 is -1.0 eV to 1.0 eV. Especially when the energy level difference between the conduction band bottom of the first sub-layer and the perovskite layer is -0.3 eV to 0.3 eV, the electron transport efficiency of the first sub-layer is relatively high, which is beneficial to improving the power conversion efficiency of the perovskite solar cells.

[0187] Compared with Comparative Examples 5 and 6, the valence band top energy level of the first sub-layer of the perovskite solar cells in Examples 9 to 14 is less than that of the perovskite layer, and the electron transport efficiency of the first sub-layer can be further improved, which is further beneficial to improving the power conversion efficiency of the perovskite solar cells.

[0188] 3. The performance test results of Examples 11, 13 to 21 are shown in Tables 7 and 8.

[0189] Table 7

[0190]

[0191] Table 8

[0192]

[0193] As can be seen from Tables 7 and 8, compared with Example 19, the energy level difference FLP1 - FLP5 between the Fermi level of the first sub-layer and the perovskite layer of the perovskite solar cells in Examples 11, 13 to 18 is ≤ 1.5 eV, and the electron transport efficiency of the first sub-layer is relatively high, which is beneficial to improving the power conversion efficiency of the perovskite solar cells.

[0194] Compared with Example 20, the energy level difference CBM1 - FLP1 between the conduction band bottom and the Fermi level of the first sub-layer of the perovskite solar cells in Examples 11, 13 to 18 is ≤ 1.5 eV, and its power conversion efficiency is higher.

[0195] Compared with Example 21, the difference in the bottom energy level of the conduction band and the top energy level of the valence band, CBM-VBM, of the first sub-layer of the perovskite solar cells in Examples 13 to 18 is ≥1.5 eV, and their power conversion efficiency is higher.

[0196] 4. The performance test results of Examples 22 to 40 are shown in Table 9.

[0197] Table 9

[0198]

[0199] As can be seen from Table 9, compared with Example 1, the electron transport layer of the perovskite solar cells in Examples 22 to 40 includes three sub-layers, which is beneficial to improving the power conversion efficiency of the perovskite solar cells.

[0200] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A perovskite solar cell, characterized in that, Comprising: A perovskite layer including a first surface and a second surface opposite to each other along its thickness direction; A hole transport layer disposed on the first surface; And An electron transport layer disposed on the second surface, the electron transport layer including a doping material, the electron transport layer including at least two sub-layers, the bottom energy level of the conduction band of each sub-layer being less than the bottom energy level of the conduction band of the hole transport layer; the top energy level of the valence band of each sub-layer being less than the top energy level of the valence band of the hole transport layer, The difference between the sub-layer of the electron transport layer close to the second surface and the bottom energy level of the conduction band of the perovskite layer is -1.0 eV to 1.0 eV, The difference between the sub-layer of the electron transport layer close to the second surface and the Fermi level of the perovskite layer is ≤ 1.5 eV, The difference between the bottom energy level of the conduction band and the Fermi level of the sub-layer of the electron transport layer close to the second surface is ≤ 1.5 eV.

2. The perovskite solar cell according to claim 1, wherein The difference between the sub-layer of the electron transport layer close to the second surface and the bottom energy level of the conduction band of the perovskite layer is -0.3 eV to 0.3 eV.

3. The perovskite solar cell according to claim 1, wherein The top energy level of the valence band of the sub-layer of the electron transport layer close to the second surface is less than the top energy level of the valence band of the perovskite layer.

4. The perovskite solar cell according to claim 1, wherein The difference between the bottom energy level of the conduction band and the top energy level of the valence band of the sub-layer of the electron transport layer close to the second surface is ≥ 1.5 eV.

5. The perovskite solar cell according to claim 1, characterized in that, The electron transport layer includes a first sub-layer, a second sub-layer and a third sub-layer stacked in sequence in a direction away from the second surface, wherein the first sub-layer is a tin oxide layer including a first doping material, and the first doping material includes an alkali metal, an alkaline earth metal, a transition metal, a poor metal, a metalloid, a non-metal element, an ionic liquid, a carboxylic acid, a phosphoric acid, a carbon derivative, a self-assembled monolayer or an organic polymer.

6. The perovskite solar cell according to claim 5, wherein The alkali metal includes at least one of Li, K, Na, Rb and Cs; The alkaline earth metal includes at least one of Be, Sr and Ba; The transition metal includes at least one of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Ta, Pt and Au; The poor metal includes at least one of Al, Ga, In, Sn, Tl, Pb and Bi; The metalloid includes at least one of B, Si, Ge, As, Sb and Te; The non-metal element includes at least one of F, Cl, Br, I, P, S and Se; The ionic liquid includes at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, ammonium chloride, ammonium sulfide, tetramethylammonium hydroxide and 2,2,2-trifluoroethanol; The carboxylic acid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 4-imidazoleacetic acid hydrochloride and acetic acid; The carbon derivatives include at least one of carbon quantum dots, carbon nanotubes, graphene, C60, C60 derivatives, graphitic carbon nitride, and C9; The self-assembled monolayers include at least one of 4-pyridinecarboxylic acid, dopamine, 3-aminopropyltriethoxysilane, and glycine; The organic polymer includes at least one of polystyrene, polyethoxyethyleneimine, polyethylene oxide, and triphenylphosphine oxide.

7. The perovskite solar cell according to claim 5, wherein The second sublayer includes an imide compound layer, a quinone compound layer, a fullerene layer, a perovskite-type oxide layer, a fluoride layer, or an oxide layer.

8. The perovskite solar cell according to claim 7, wherein The imide compound layer includes an imide compound or a derivative of the imide compound, and the imide compound includes phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide; The quinone compound layer includes a quinone compound or a derivative of the quinone compound, and the quinone compound includes benzoquinone, naphthoquinone, phenanthraquinone, or anthraquinone; The perovskite-type oxide layer includes strontium titanate, calcium titanate, barium titanate, lithium titanate, iron titanate, nickel titanate, or cobalt titanate; The fluoride layer includes lithium fluoride or calcium fluoride; The oxide layer includes an oxide layer of the following elements: Ce, Mg, Si, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, or Cr.

9. The perovskite solar cell according to claim 5, characterized in that, The third sublayer includes a metal oxide layer or a metal oxide layer containing a second doping material, and the metal oxide layer includes a SnO2 layer, an In2O3 layer, a ZnO layer, a CdO layer, a NiO layer, a CdIn2O4 layer, a Cd2SnO4 layer, a Zn2SnO4 layer, a MgIn2O4 layer, a ZnIn2O4 layer, a CoIn3O6 layer, a ZnV2O6 layer, a CuAlO2 layer, or a CuGaO2 layer.

10. The perovskite solar cell according to claim 9, wherein The SnO2 layer includes a second doping material, and the elements of the second doping material include at least one of F, Sb, P, As, Te, and Cl; The In2O3 layer includes a second doping material, and the elements of the second doping material include at least one of W, Mn, Zr, Ti, Sb, F, and Ag; The ZnO layer includes a second doping material, and the elements of the second doping material include at least one of Ga, In, F, N, B, and Al.

11. A photovoltaic module, characterized in that, Comprising the perovskite solar cell according to any one of claims 1 to 10.

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