Perovskite heterojunction solar cell and preparation method thereof

Abstract

The invention provides a perovskite heterojunction solar cell and a preparation method thereof. The perovskite heterojunction solar cell provided by the invention comprises a substrate electrode, a hole transport layer, a two-dimensional material functional layer, a perovskite light absorption layer, an electron transport layer and a top electrode which are stacked in sequence, wherein the two-dimensional material functional layer is a WSe2 thin film, the thickness of the WSe2 thin film is 3-50 nm, and the number of layers of a WSe2 material in the WSe2 thin film is 4-70. According to the perovskite heterojunction solar cell, the WSe2 thin film is introduced between the hole transport layer and the perovskite light absorption layer to serve as the two-dimensional material function layer, an effective built-in electric field is formed, the separation efficiency and mobility of carriers are improved, recombination of photon-generated carriers is reduced, and therefore the photoelectric conversion efficiency and stability of the perovskite heterojunction solar cell are improved, and the perovskite heterojunction solar cell is suitable for being applied to the field of solar cell devices. The perovskite solar cell has a wide application prospect in the field of perovskite solar cells.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a perovskite heterojunction solar cell and a preparation method thereof. Background Art

[0002] With growing global energy demand and increasingly severe environmental issues, solar energy has attracted widespread attention as a clean, renewable energy source. Perovskite solar cells have become a research hotspot due to their high photoelectric conversion efficiency, low cost, and simple fabrication process. However, the instability of perovskite materials, particularly their rapid degradation under moisture and thermal stress, has limited their commercialization.

[0003] In order to improve the photoelectric conversion efficiency and stability of perovskite solar cells, researchers have tried many methods, but mainly focused on perovskite materials. However, there is less research on how to form a heterojunction structure to improve the photoelectric conversion efficiency and stability of solar cells.

[0004] In view of this, this application is hereby filed. Summary of the Invention

[0005] The main purpose of the present application is to provide a method to solve the problem that researchers in the prior art mainly focus on perovskite materials to improve the photoelectric conversion efficiency and stability of perovskite solar cells, and how to form a heterojunction structure to improve the photoelectric conversion efficiency and stability of perovskite solar cells.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a perovskite heterojunction solar cell is provided, which includes a substrate electrode, a hole transport layer, a two-dimensional material functional layer, a perovskite light absorption layer, an electron transport layer and a top electrode stacked in sequence; wherein, the two-dimensional material functional layer is a WSe2 thin film, the thickness of the WSe2 thin film is 5-50nm, and the number of layers of WSe2 material in the WSe2 thin film is 4-70.

[0007] Furthermore, the number of layers of WSe2 material in the WSe2 film is 7-43, preferably 7-29, and more preferably 7-14.

[0008] Furthermore, the thickness of the WSe2 film is 5-30 nm, preferably 5-20 nm, and more preferably 5-10 nm.

[0009] Furthermore, the substrate electrode includes a transparent conductive glass substrate and a transparent conductive oxide attached to the transparent conductive glass substrate, wherein the transparent conductive oxide includes at least one of indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, preferably indium tin oxide or fluorine-doped tin oxide.

[0010] Furthermore, the thickness of the substrate electrode is 100-400 nm, preferably 250-350 nm, and more preferably 300 nm.

[0011] Furthermore, the hole transport layer material includes NiO x , CuSCN or CuI, wherein x is 1-1.5, and the material of the hole transport layer is preferably NiO x .

[0012] Furthermore, the thickness of the hole transport layer is 10-40 nm, preferably 25-35 nm, and more preferably 30 nm.

[0013] Furthermore, the material of the perovskite light-absorbing layer includes at least one of a long-chain organic amine salt, a short-chain organic amine salt, an alkali metal halide, and a divalent metal halide.

[0014] Furthermore, the thickness of the perovskite light-absorbing layer is 300-800 nm, preferably 400-700 nm, and more preferably 500-600 nm.

[0015] Furthermore, the material of the electron transport layer includes one of TiO2, SnO2 or fullerene derivatives, preferably fullerene C 60 .

[0016] Furthermore, the thickness of the electron transport layer is 10-100 nm, preferably 20-80 nm, more preferably 30-60 nm, and most preferably 30-50 nm.

[0017] Furthermore, the material of the top electrode includes at least one of gold, silver, copper or amorphous carbon, preferably copper.

[0018] Furthermore, the thickness of the top electrode is 50-500 nm, preferably 100-400 nm, and more preferably 200-300 nm.

[0019] According to another aspect of the present application, a method for preparing the above-mentioned perovskite heterojunction solar cell is provided, which comprises the following steps: providing a substrate electrode, depositing a hole transport layer on the surface of the substrate electrode, transferring the WSe2 thin film to the surface of the hole transport layer to form a two-dimensional material functional layer, spin coating the surface of the two-dimensional material functional layer to prepare a perovskite light absorption layer, depositing an electron transport layer on the surface of the perovskite light absorption layer, and depositing a top electrode on the surface of the electron transport layer to obtain a solar cell.

[0020] Furthermore, the substrate electrode is cleaned and dried with an organic solvent and water in sequence, and then a hole transport layer is deposited on the surface of the substrate electrode.

[0021] Furthermore, the hole transport layer is formed by physical vapor deposition.

[0022] Furthermore, the electron transport layer is formed by chemical vapor deposition.

[0023] Furthermore, the top electrode is formed by thermal evaporation deposition.

[0024] Further, the WSe2 film is transferred to the surface of the hole transport layer, placed at 90-110°C for 15-25 minutes, and then the electron transport layer is deposited on the surface of the WSe2 film.

[0025] Furthermore, the preparation method of the perovskite light absorbing layer includes: providing a perovskite precursor solution, spin-coating the perovskite precursor solution on the surface of the hole transport layer and performing annealing treatment to obtain the perovskite light absorbing layer.

[0026] By applying the technical solution of this application, a WSe2 thin film is introduced as a two-dimensional material functional layer between the hole transport layer and the perovskite light-absorbing layer. This creates an effective built-in electric field, improves the separation efficiency and mobility of carriers, reduces the recombination of photogenerated carriers, and thus improves the photoelectric conversion efficiency of solar cells. Furthermore, the introduction of the WSe2 thin film also slows the degradation rate of the perovskite material and improves the stability of perovskite solar cells, which has broad application prospects in the field of optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0028] Figure 1 A graph showing the relationship between the open circuit voltage and the short circuit current density of the perovskite heterojunction solar cell provided in Example 1;

[0029] Figure 2 The relationship spectrum between the open circuit voltage and short circuit current density of the perovskite heterojunction solar cell provided in Comparative Example 1. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the embodiments.

[0031] As analyzed in the background of this application, the commercialization of perovskite solar cells is limited by the instability of the perovskite material, especially its rapid degradation under moisture and thermal stress. In order to improve the photoelectric conversion efficiency and stability of perovskite solar cells, researchers have mainly focused on perovskite materials, but there is less research on how to form a heterojunction structure to improve the photoelectric conversion efficiency and stability of solar cells. To address this problem, this application provides a perovskite heterojunction solar cell and a method for preparing the same.

[0032] In a first typical embodiment of the present application, a perovskite heterojunction solar cell is provided, which includes a substrate electrode, a hole transport layer, a two-dimensional material functional layer, a perovskite light absorption layer, an electron transport layer and a top electrode stacked in sequence, wherein the two-dimensional material functional layer is a WSe2 thin film, the thickness of the WSe2 thin film is 5-50nm, and the number of layers of WSe2 material in the WSe2 thin film is 4-70.

[0033] Tungsten diselenide (WSe2) is a typical transition metal chalcogenide (TMD) with unique physical and chemical properties, such as direct bandgap semiconductor characteristics and high electron mobility. These characteristics make WSe2 show great application potential in optoelectronic devices. The direct bandgap characteristics of WSe2 give it advantages in light absorption and carrier separation, while its high electron mobility helps improve the response speed and efficiency of devices.

[0034] In order to improve the photoelectric conversion efficiency and stability of perovskite solar cells, introducing a suitable interface layer into the perovskite solar cell structure has become an effective strategy. Among them, WSe2 is considered to be an ideal window layer material due to its excellent conductivity and optical properties.

[0035] This application introduces a WSe2 thin film as a two-dimensional material functional layer between the hole transport layer and the perovskite light-absorbing layer, forming an effective built-in electric field, improving the separation efficiency and mobility of carriers, and reducing the recombination of photogenerated carriers, thereby improving the photoelectric conversion efficiency of perovskite heterojunction solar cells. At the same time, the introduction of the WSe2 thin film also slows the degradation rate of the perovskite material and improves the stability of perovskite heterojunction solar cells, which has broad application prospects in the field of optoelectronic devices.

[0036] In the present application, the thickness of the WSe2 film is 3 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or a range consisting of any two values. The number of layers of WSe2 material in the WSe2 film is 4, 5, 6, 7, 8, 9, 10, 14, 15, 20, 25, 29, 30, 35, 40, 50, 60, 70, or a range consisting of any two values.

[0037] In some embodiments, when the number of layers of WSe2 material in the WSe2 film is 7-43, the perovskite heterojunction solar cell has better photoelectric conversion efficiency and stability, especially when the number of layers of WSe2 material is 7-29, its photoelectric conversion efficiency is higher, especially when the number of layers of WSe2 material is 7-14, the photoelectric conversion efficiency and stability of the perovskite heterojunction solar cell are better.

[0038] In some embodiments, the thickness of the WSe2 film is 5-30 nm, which is more conducive to improving the stability and photoelectric conversion efficiency of the perovskite heterojunction solar cell, especially when the thickness of the WSe2 film is 5-20 nm, the stability of the perovskite heterojunction solar cell is further improved, especially when the thickness of the WSe2 film is 5-10 nm, the photoelectric conversion efficiency and stability of the perovskite heterojunction solar cell are higher.

[0039] In some embodiments, the substrate electrode includes a transparent conductive glass substrate and a transparent conductive oxide attached to the transparent conductive glass substrate, wherein the transparent conductive oxide includes any one or more of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO). In particular, when the transparent conductive oxide is indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), it is more conducive to improving the stability of the perovskite heterojunction solar cell.

[0040] In some embodiments, the thickness of the substrate electrode is 100-400 nm, which is more conducive to improving the stability of the perovskite heterojunction solar cell. In particular, when the thickness of the substrate electrode is 250-350 nm, the stability of the perovskite heterojunction solar cell is even better. In particular, when the thickness of the substrate electrode is 300 nm, the stability of the perovskite heterojunction solar cell is the best.

[0041] Typically, but not limited to, the thickness of the substrate electrode is 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, or a range consisting of any two of these values.

[0042] In some embodiments, the material of the hole transport layer includes NiO x (x is 1-1.5), CuSCN or CuI, it is beneficial to improve the photoelectric conversion efficiency of solar cells. Especially when the hole transport layer material is NiO x When (x is 1), perovskite heterojunction solar cells have excellent photoelectric conversion efficiency and are more conducive to reducing costs.

[0043] In some embodiments, when the thickness of the hole transport layer is 10-40 nm, the perovskite heterojunction solar cell has excellent photoelectric conversion efficiency, especially when the thickness of the hole transport layer is 25-35 nm, which is more conducive to improving the photoelectric conversion efficiency while reducing costs. In particular, when the thickness of the hole transport layer is 30 nm, the perovskite heterojunction solar cell is more conducive to balancing lower preparation costs and better photoelectric conversion efficiency and stability.

[0044] Typically, but not limited to, the thickness of the hole transport layer is 10 nm, 15 nm, 20 nm, 25 nm, 28 nm, 30 nm, 32 nm, 35 nm, 40 nm, or a range consisting of any two of these values.

[0045] In some embodiments, the material of the perovskite light-absorbing layer includes any one or more of a long-chain organic amine salt, a short-chain organic amine salt, an alkali metal halide, and a divalent metal halide.

[0046] Specifically, long-chain organic amine salts include, but are not limited to, any one or more of isopropylamine hydroiodide, naphthylamine hydroiodide, benzylamine hydroiodide, phenylethylamine hydroiodide, phenyltrimethylamine hydroiodide, butylamine hydroiodide, isobutylamine hydroiodide, tert-butylamine hydroiodide, ethylamine hydroiodide, hexylamine hydroiodide, octylamine hydroiodide, aniline hydroiodide, amphetamine, ethylenediamine dihydroiodide, 1,4-phenylenediamine dihydroiodide, decanediamine dihydroiodide, propylenediamine dihydroiodide, ethylenedioxybisethylamine dihydroiodide, 1,6-hexanediamine dihydroiodide, 1,8-octanediamine dihydroiodide, 1,4-phenylenediamine dihydroiodide, m-phenylenediamine dihydroiodide, o-phenylenediamine dihydroiodide, and 1,4-dimethyldiamine dihydroiodide.

[0047] The short-chain organic amine salt includes but is not limited to at least one of formamidine hydrochloride, methylamine hydrochloride, dimethylamine hydrochloride, formamidine hydrobromide, methylamine hydrobromide, dimethylamine hydrobromide, formamidine hydroiodide, methylamine hydroiodide, and dimethylamine hydroiodide; the alkali metal halide is selected from at least one of CsI, RbI, KI, NaI, LiI, CsBr, RbBr, KBr, NaBr, LiBr, CsCl, RbCl, KCl, NaCl, and LiCl.

[0048] The divalent metal halide includes but is not limited to at least one of PbI2, PbBr2, PbCl2, GeI2, GeBr2, GeCl2, SnI2, SnBr2, and SnCl2.

[0049] In some embodiments, the thickness of the perovskite light absorbing layer is 300-800 nm, which is beneficial to improving the photoelectric conversion efficiency and stability of the perovskite heterojunction solar cell. In particular, when the thickness of the perovskite light absorbing layer is 400-700 nm, it is more beneficial to improving the photoelectric conversion efficiency and stability of the perovskite heterojunction solar cell. In particular, when the thickness of the perovskite light absorbing layer is 500-600 nm, the photoelectric conversion efficiency and stability of the perovskite heterojunction solar cell are even better.

[0050] Typically, but not limited to, the thickness of the perovskite light absorbing layer is 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, or a range consisting of any two values.

[0051] In some embodiments, the material of the electron transport layer includes any one or more of TiO2, SnO2 or fullerene derivatives. 60 When the electron transport layer has a better electron transport efficiency.

[0052] Fullerene derivatives are derivatives of C60 or other fullerene molecules. Fullerenes are molecules composed of carbon atoms. The spherical C60 fullerene molecule is known for its soccer-ball-like structure and is also called a "buckyball." C60 fullerene consists of 60 carbon atoms arranged in pentagons and hexagons to form a closed sphere. Besides C60, there are other types of fullerenes, such as C70, which consists of 70 carbon atoms and is shaped like an ellipse.

[0053] In some embodiments, the thickness of the electron transport layer is 10-100 nm, which is more conducive to improving the stability of the perovskite heterojunction solar cell. In particular, when the thickness of the electron transport layer is 20-80 nm, it is more conducive to improving the photoelectric conversion efficiency of the perovskite heterojunction solar cell. In particular, when the thickness of the electron transport layer is 30-60 nm, it is more conducive to taking into account excellent photoelectric conversion efficiency and stability. When the thickness of the electron transport layer is 30-50 nm, the perovskite heterojunction solar cell has better photoelectric conversion rate and stability while being more conducive to reducing costs.

[0054] Typically, but not limited to, the thickness of the electron transport layer is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 90 nm, 100 nm, or a range consisting of any two values.

[0055] In some embodiments, the material of the top electrode includes any one or more of gold, silver, copper or amorphous carbon. In particular, when the top electrode is copper, it is more conducive to reducing costs while taking into account the stability of the perovskite heterojunction solar cell.

[0056] In some embodiments, when the thickness of the top electrode is 50-500 nm, it is more conducive to improving the photoelectric conversion efficiency of the perovskite heterojunction solar cell, especially when the thickness of the top electrode is 100-400 nm, the perovskite heterojunction solar cell is more conducive to taking into account excellent stability and photoelectric conversion efficiency, especially when the thickness of the top electrode is 200-300 nm, it is more conducive to improving stability and photoelectric conversion efficiency, and is conducive to reducing costs.

[0057] Typically, but not limited to, the thickness of the top electrode is 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, or a range consisting of any two of these values.

[0058] In a second typical embodiment of the present application, a method for preparing the above-mentioned perovskite heterojunction solar cell is provided, and the preparation method includes the following steps: step S1, providing a substrate electrode, and depositing a hole transport layer on the surface of the substrate electrode; step S2, transferring the WSe2 thin film to the surface of the hole transport layer away from the substrate electrode to form a two-dimensional material functional layer; step S3, spin coating the surface of the two-dimensional material functional layer to prepare a perovskite light absorbing layer; step S4, depositing an electron transport layer on the surface of the perovskite light absorbing layer; step S5, depositing a top electrode on the surface of the electron transport layer away from the WSe2 thin film to obtain a perovskite heterojunction solar cell.

[0059] The preparation method of the perovskite heterojunction solar cell provided in the present application has a simple process and is easy to operate, which is conducive to large-scale production and further reduces the preparation cost.

[0060] In some embodiments, a WSe2 thin film is obtained by stripping a bulk WSe2 single crystal. Specifically, a tape stripping technique is used in which a WSe2 single crystal is placed on a layer of tape, which is then covered with another layer of tape. The WSe2 single crystal is stripped by gently pressing and slowly peeling off the top layer of tape to obtain a WSe2 thin film.

[0061] In some embodiments, in step S1, the substrate electrode is first cleaned with an organic solvent and water to remove impurities and oil on the surface, and then dried to ensure the cleanliness of the substrate electrode. The drying method is, for example, to dry the surface of the substrate electrode using a dust-free cloth or a nitrogen gun.

[0062] The above-mentioned organic solvents are commonly used solvents in the art, including but not limited to acetone, isopropyl alcohol, etc.

[0063] In some embodiments, in step S1 , the hole transport layer is formed by physical vapor deposition to improve the stability of the combination of the hole transport layer and the substrate electrode.

[0064] In some specific embodiments, the preparation of the hole transport layer includes the following steps: depositing a layer of NiO on the substrate electrode by physical vapor deposition (PVD) technology. x (x is 1-1.5) as a hole transport layer and then undergoes annealing. The annealing temperature is controlled at 200-400 ° C to enhance the NiO x The crystallinity and stability of the NiO layer. x The thickness of the layer is controlled between 20-40 nm to further improve hole transport.

[0065] In some embodiments, in step S2, the WSe2 film is transferred to the surface of the hole transport layer, and is placed at 90-110°C for 15-25 minutes for heat treatment so that the WSe2 film is tightly combined with the hole transport layer, and then the electron transport layer is deposited on the surface of the WSe2 film.

[0066] Specifically, the temperature of the heating treatment is 90°C, 92°C, 95°C, 98°C, 100°C, 102°C, 105°C, 108°C, 110°C or a range consisting of any two numerical values; the temperature of the heating treatment is 15min, 18min, 20min, 22min, 25min or a range consisting of any two numerical values.

[0067] In some specific embodiments, the WSe2 film is transferred to the surface of the hole transport layer according to the following steps:

[0068] (1) PDMS (polydimethylsiloxane) sheet transfer: The PDMS sheet is placed in contact with the WSe2 film, and the WSe2 film is adhered by the viscosity of PDMS. Then the PDMS sheet is quickly peeled off and the WSe2 film is transferred to the surface of the PDMS sheet.

[0069] (2) Transfer to the hole transport layer: The PDMS sheet with the WSe2 film is placed in contact with the hole transport layer and placed at 100°C for 20 minutes using a temperature control table to allow the WSe2 film to be tightly bonded to the hole transport layer. Then, the PDMS sheet is slowly lifted, leaving the WSe2 film on the surface of the hole transport layer.

[0070] In some embodiments, a method for preparing a perovskite light absorbing layer includes: providing a perovskite precursor solution, spin-coating the perovskite precursor solution on a surface of a hole transport layer, and performing an annealing treatment to obtain the perovskite light absorbing layer.

[0071] Illustratively, the annealing temperature is 80-150°C, such as 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or a range consisting of any two values.

[0072] Exemplarily, the spin coating speed is 3000-5000 rpm and the spin coating time is 30-60 s, so as to improve the spin coating efficiency.

[0073] In some specific embodiments, the perovskite light absorbing layer is formed according to the following steps:

[0074] (1) Weigh a certain amount of FAI (formamidine hydroiodide), MACl (methylammonium chloride), and PbI2 (the molar ratio of the three is 1.0:0.1:1) in a glass bottle, add a certain amount of solvent DMFA (dimethylformamide), place the glass bottle in an ultrasonic container, and ultrasonicate until the solids are completely dissolved to form a perovskite precursor solution;

[0075] (2) Spin coating the perovskite precursor solution on the hole transport layer. The rotation speed can be set to 3000-5000 rpm and the spin coating time is 30-60 s. The obtained product is then placed on a heating table for annealing to form a perovskite film (600 nm). The annealing temperature is 80-150 ° C. The solvent is removed to obtain a perovskite light absorbing layer.

[0076] In some embodiments, the electron transport layer is formed by chemical vapor deposition to improve the density of the electron transport layer and the perovskite light absorbing layer, thereby improving the efficiency of electron transport.

[0077] In some embodiments, the top electrode is formed by thermal evaporation deposition. Specifically, a layer of metal or non-metal is deposited on the electron transport layer using thermal evaporation technology to serve as the top electrode to improve electrical contact and collection performance.

[0078] In a third typical embodiment of the present application, a photoelectric device is further provided, which includes the perovskite heterojunction solar cell provided by the first aspect or the perovskite heterojunction solar cell obtained by the preparation method provided by the second aspect.

[0079] The optoelectronic device provided in the present application utilizes a perovskite heterojunction solar cell to introduce a WSe2 thin film as a two-dimensional material functional layer between the hole transport layer and the perovskite light absorption layer, thereby forming an effective heterojunction built-in electric field, improving the carrier separation efficiency and mobility, and reducing the recombination of photogenerated carriers, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell, and thus making the optoelectronic device have good application potential.

[0080] The beneficial effects of the present application will be further illustrated below with reference to examples and comparative examples.

[0081] Example 1

[0082] This embodiment provides a perovskite heterojunction solar cell, which includes a substrate electrode, a hole transport layer, a two-dimensional material functional layer, a perovskite light absorption layer, an electron transport layer and a top electrode stacked in sequence, wherein the substrate electrode is ITO conductive glass with a thickness of 300nm; the hole transport layer is made of NiO x (x=1), with a thickness of 30nm; the two-dimensional material functional layer is a WSe2 film, and the number of WSe2 material layers in the WSe2 film is 7, with a thickness of 5nm; the material of the perovskite light absorption layer is FAPbI3, with a thickness of 600nm, and the material of the electron transport layer is fullerene C 60 , with a thickness of 40nm; the material of the top electrode is copper, with a thickness of 250nm.

[0083] The above-mentioned perovskite heterojunction solar cell is prepared according to the following steps:

[0084] (1) Cleaning the ITO conductive glass substrate: Provide a 300nm thick ITO conductive glass substrate. Use acetone, isopropyl alcohol, and deionized water to clean the ITO conductive glass substrate in sequence to remove impurities and oil stains on the surface of the ITO conductive glass substrate. Then use a dust-free cloth or nitrogen gun to blow dry the substrate surface to ensure cleanliness.

[0085] (2) Preparation of hole transport layer: On the ITO conductive glass, a layer of NiO with a thickness of 30nm was deposited by physical vapor deposition (PVD) technology as a hole transport layer, and then annealed. The annealing temperature was controlled at 300℃ to enhance the NiO x crystallinity and stability of the layer.

[0086] (3) Preparation of two-dimensional material functional layer: Place the bulk WSe2 single crystal on tape, then cover it with another layer of tape. By gently pressing and slowly peeling off the upper tape, a WSe2 film with a thickness of 5 nm and 7 WSe2 material layers is peeled off.

[0087] The peeled WSe2 film is placed in contact with a polydimethylsiloxane (PDMS) sheet, and the sheet is adhered using the stickiness of PDMS. The PDMS sheet is then quickly peeled off to transfer the WSe2 film to the surface of the PDMS sheet.

[0088] The PDMS sheet with the WSe2 film was placed in contact with the hole transport layer and placed at 100°C for 20 minutes using a temperature control table to allow the WSe2 film to tightly bond to the hole transport layer (NiO layer). Then the PDMS sheet was slowly lifted, leaving the WSe2 film on the surface of the hole transport layer (NiO layer).

[0089] (4) Preparation of perovskite light-absorbing layer: weigh a certain amount of FAI (formamidine hydroiodide), MACl (methylammonium chloride), and PbI2 (the molar ratio of the three is 1.0:0.1:1) in a glass bottle, add a certain amount of solvent DMF (dimethylformamide), place the glass bottle in an ultrasonic container, and ultrasonicate until the solid is completely dissolved to form a perovskite precursor solution; spin-coat the perovskite precursor solution on the two-dimensional material functional layer, the speed can be set to 4000 rpm, the spin-coating time is 45 s, and then place the obtained product on a heating table for annealing to form a perovskite film (600 nm), the annealing temperature is 120°C, and the solvent is removed to obtain a perovskite light-absorbing layer.

[0090] (5) Preparation of electron transport layer: On the perovskite light absorption layer, a layer of fullerene C60 with a thickness of 40 nm is deposited by chemical vapor deposition (CVD) technology as an electron transport layer.

[0091] (6) Preparation of the top electrode: A layer of copper with a thickness of 250 nm was deposited on the electron transport layer by thermal evaporation technology as the top electrode, thereby obtaining the above-mentioned perovskite heterojunction solar cell.

[0092] Example 2

[0093] The difference between this embodiment and Example 1 is that the thickness of the WSe2 film serving as the two-dimensional material functional layer is 3 nm, and the number of layers of WSe2 material in the WSe2 film is 4.

[0094] Example 3

[0095] The difference between this embodiment and Example 1 is that the thickness of the WSe2 film serving as the two-dimensional material functional layer is 10 nm, and the number of layers of WSe2 material in the WSe2 film is 14.

[0096] Example 4

[0097] The difference between this embodiment and Example 1 is that the thickness of the WSe2 film serving as the two-dimensional material functional layer is 30 nm, and the number of layers of WSe2 material in the WSe2 film is 43.

[0098] Example 5

[0099] The difference between this embodiment and Example 1 is that the thickness of the WSe2 film serving as the two-dimensional material functional layer is 50 nm, and the number of layers of WSe2 material in the WSe2 film is 70.

[0100] Example 6

[0101] The difference between this embodiment and embodiment 1 is that the thickness of the perovskite light absorbing layer is 300 nm.

[0102] Example 7

[0103] The difference between this embodiment and embodiment 1 is that the thickness of the perovskite light absorbing layer is 800 nm.

[0104] Example 8

[0105] The difference between this embodiment and embodiment 1 is that the thickness of the ITO conductive glass is 250 nm, the hole transport layer (TiO x The thickness of the electron transport layer (fullerene C 60 The thickness of the copper layer is 300 nm and the thickness of the top electrode is 300 nm.

[0106] Example 9

[0107] The difference between this embodiment and embodiment 1 is that the thickness of the ITO conductive glass is 350 nm, the hole transport layer (TiO x The thickness of the electron transport layer (fullerene C 60 The thickness of the top electrode (copper layer) is 200 nm.

[0108] Example 10

[0109] The difference between this embodiment and embodiment 1 is that the thickness of the ITO conductive glass is 400 nm, the hole transport layer (TiO x The thickness of the electron transport layer (fullerene C 60 The thickness of the top electrode (copper layer) is 100 nm.

[0110] Example 11

[0111] The difference between this embodiment and embodiment 1 is that the thickness of the ITO conductive glass is 100 nm, the hole transport layer (TiO x The thickness of the electron transport layer (fullerene C 60 The thickness of the top electrode (copper layer) is 400 nm.

[0112] Comparative Example 1

[0113] The difference between this comparative example and Example 1 is that no two-dimensional material functional layer is provided.

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 1 is that MoS2 film is used instead of WSe2 film as the two-dimensional material functional layer.

[0116] Comparative Example 3

[0117] The difference between this comparative example and Example 1 is that the thickness of the WSe2 film serving as the two-dimensional material functional layer is 1.4 nm, and the number of layers of WSe2 material in the WSe2 film is 2.

[0118] Test example

[0119] The perovskite heterojunction solar cells provided in the above examples and comparative examples were tested for performance, photoelectric conversion efficiency, and stability. The results are shown in Table 1.

[0120] Among them, (1) the detection method of photoelectric conversion efficiency is: under room temperature, using a 3A solar simulator at 100mW / cm 2 Under the light intensity, the photoelectric conversion efficiency of the perovskite heterojunction solar cell was tested, and the effective area of the cell was 0.049cm 2 .

[0121] Table 1

[0122]

[0123] Figure 1 The relationship between the open circuit voltage and short circuit current density of the perovskite heterojunction solar cell provided in Example 1 is shown in FIG. Figure 1 It can be seen that when the open circuit voltage of the titanium ore heterojunction solar cell provided in Example 1 is 1.098 V, the short circuit current density is 24.31 mA / cm 2 .

[0124] Figure 2 The relationship between the open circuit voltage and short circuit current density of the perovskite solar cell provided in Comparative Example 1 is shown in FIG. Figure 2 It can be seen that when the open circuit voltage of the perovskite solar cell provided in Comparative Example 1 is 1.058 V, the short circuit current density is 25.13 mA / cm 2 .

[0125] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0126] The perovskite heterojunction solar cells provided in Examples 1-11 of the present application form an effective built-in electric field by introducing a WSe2 thin film (with a thickness of 3-50nm and a number of layers of WSe2 material of 4-70) as a two-dimensional material functional layer between the hole transport layer and the perovskite light absorbing layer, thereby improving the separation efficiency and mobility of carriers and reducing the recombination of photogenerated carriers, thereby improving the photoelectric conversion efficiency of the perovskite heterojunction solar cell. In contrast, in Comparative Example 1, when the two-dimensional material functional layer is not provided, its photoelectric conversion efficiency is greatly reduced. It can be seen from Comparative Example 2 that when the two-dimensional material functional layer is a MoS2 thin film, its photoelectric conversion efficiency is also significantly reduced. And it can be seen from Comparative Example 3 that when the thickness of the two-dimensional material functional layer is less than 3nm, its photoelectric conversion efficiency is also significantly reduced. It can be seen from this that the present application forms an effective built-in electric field by introducing WSe2 thin film as a two-dimensional material functional layer between the hole transport layer and the perovskite light absorption layer, thereby improving the carrier separation efficiency and mobility, reducing the recombination of photogenerated carriers, and thus improving the photoelectric conversion efficiency and stability of perovskite heterojunction solar cells, and has broad application prospects in the field of perovskite solar cells.

[0127] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A perovskite heterojunction solar cell, characterized in that: The perovskite heterojunction solar cell includes a substrate electrode, a hole transport layer, a two-dimensional material functional layer, a perovskite light absorption layer, an electron transport layer and a top electrode stacked in sequence; wherein the two-dimensional material functional layer is a WSe2 thin film, the thickness of the WSe2 thin film is 3-50nm, and the number of layers of WSe2 material in the WSe2 thin film is 4-70.

2. The perovskite heterojunction solar cell according to claim 1, characterized in that The number of layers of WSe2 material in the WSe2 film is 7-43, preferably 7-29, more preferably 7-14; And / or, the thickness of the WSe2 film is 5-30 nm, preferably 5-20 nm, more preferably 5-10 nm.

3. The perovskite heterojunction solar cell according to claim 1, characterized in that The substrate electrode comprises a transparent conductive glass substrate and a transparent conductive oxide attached to the transparent conductive glass substrate, wherein the transparent conductive oxide comprises at least one of indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, preferably indium tin oxide or fluorine-doped tin oxide; And / or, the thickness of the substrate electrode is 100-400 nm, preferably 250-350 nm, more preferably 300 nm.

4. The perovskite heterojunction solar cell according to claim 1, characterized in that The material of the hole transport layer includes NiO x , CuSCN or CuI, wherein x is 1-1.5, and the material of the hole transport layer is preferably NiO x ; And / or, the thickness of the hole transport layer is 10-40 nm, preferably 25-35 nm, more preferably 30 nm.

5. The perovskite heterojunction solar cell according to claim 1, characterized in that: The material of the perovskite light-absorbing layer includes at least one of a long-chain organic amine salt, a short-chain organic amine salt, an alkali metal halide, and a divalent metal halide; And / or, the thickness of the perovskite light absorbing layer is 300-800 nm, preferably 400-700 nm, more preferably 500-600 nm.

6. The perovskite heterojunction solar cell according to claim 1, characterized in that The material of the electron transport layer includes one of TiO2, SnO2 or fullerene derivatives, preferably fullerene C 60 ; And / or, the thickness of the electron transport layer is 10-100 nm, preferably 20-80 nm, more preferably 30-60 nm, and most preferably 30-50 nm.

7. The perovskite heterojunction solar cell according to any one of claims 1 to 6, characterized in that The material of the top electrode includes at least one of gold, silver, copper or amorphous carbon, preferably copper; And / or, the thickness of the top electrode is 50-500 nm, preferably 100-400 nm, more preferably 200-300 nm.

8. A method for preparing a perovskite heterojunction solar cell according to any one of claims 1 to 7, characterized in that: The preparation method includes the following steps: providing a substrate electrode, depositing a hole transport layer on the surface of the substrate electrode, transferring a WSe2 thin film to the surface of the hole transport layer to form the two-dimensional material functional layer, spin coating the surface of the two-dimensional material functional layer to prepare the perovskite light absorption layer, depositing an electron transport layer on the surface of the perovskite light absorption layer, and depositing a top electrode on the surface of the electron transport layer to obtain the solar cell.

9. The method for preparing a perovskite heterojunction solar cell according to claim 8, wherein: After the substrate electrode is cleaned and dried with an organic solvent and water in sequence, the hole transport layer is deposited on the surface of the substrate electrode; And / or, the hole transport layer is formed by physical vapor deposition; And / or, the electron transport layer is formed by chemical vapor deposition; And / or, the top electrode is formed by thermal evaporation deposition.

10. The method for preparing a perovskite heterojunction solar cell according to claim 8 or 9, characterized in that: The WSe2 film is transferred to the surface of the hole transport layer, placed at 90-110° C. for 15-25 minutes, and then the electron transport layer is deposited on the surface of the WSe2 film; And / or, the method for preparing the perovskite light absorbing layer includes: providing a perovskite precursor solution, spin-coating the perovskite precursor solution on the surface of the hole transport layer and performing annealing treatment to obtain the perovskite light absorbing layer.

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