Preparation method of nickel oxide thin film and preparation method of perovskite solar cell

Abstract

The invention provides a preparation method of a nickel oxide thin film and a preparation method of a perovskite solar cell. The preparation method of the nickel oxide film comprises the following steps: providing a transparent conductive substrate, wherein the transparent conductive substrate is provided with a first surface; a nickel oxide material is deposited on the first surface, heat treatment and passivation treatment are carried out on the nickel oxide material to form a nickel oxide thin film, and heat treatment is carried out in the humidity atmosphere. According to the invention, the conductivity and the film quality of the nickel oxide film are remarkably improved, so that the problem that the conductivity and the film quality of the nickel oxide film are relatively poor is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and in particular to a method for preparing a nickel oxide thin film, a nickel oxide thin film, a method for preparing a perovskite solar cell, and a perovskite solar cell. Background Art

[0002] The hole transport layer is a key material in perovskite solar cells, which is used to transport and collect photogenerated holes, thus playing an important role in the performance and efficiency of perovskite solar cells. The hole transport layers commonly used in perovskite solar cells mainly include Spiro-OMeTAD and PEDOT:PSS. However, Spiro-OMeTAD has poor stability and is expensive, while PEDOT:PSS has certain acidity and water absorption and poor stability. Therefore, inorganic hole transport layers have received increasing attention due to their excellent stability and high carrier mobility. Among them, NiO x Due to its good hole transport properties, its application in perovskite solar cells is becoming more and more prominent. x The hole transport layer has a series of advantages such as high hole mobility, relative stability, easy preparation, low cost and matching with the perovskite valence band.

[0003] However, NiO x The hole transport layer has the following main disadvantages: first, the interface contact between NiOx and the perovskite film is poor, which is not conducive to the growth of high-quality perovskite films and may produce certain interface defects; second, pure NiO x The conductivity of the film is not good enough, which limits the improvement of the short-circuit current (Jsc) of perovskite solar cells based on nickel oxide hole transport layers.

[0004] Therefore, how to prepare high-quality NiOx thin films remains an urgent problem to be solved. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing a nickel oxide film to solve the problems of poor conductivity and film quality of the nickel oxide film in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing a nickel oxide thin film is provided, comprising: providing a transparent conductive substrate, the transparent conductive substrate having a first surface; depositing a nickel oxide material onto the first surface; performing a heat treatment and a passivation treatment on the nickel oxide material deposited onto the first surface to form a nickel oxide thin film, wherein the heat treatment is performed in a humid atmosphere.

[0007] Optionally, the nickel oxide material deposited on the first surface is subjected to heat treatment, including: placing the transparent conductive substrate in a first container to perform heat treatment on the nickel oxide material, wherein the humidity in the first container is 20-45%.

[0008] Optionally, the heat treatment temperature is 100-200° C., and the heat treatment time is 20-60 min.

[0009] Optionally, the nickel oxide material deposited on the first surface is passivated, including: using a glow discharge plasma treatment technology to passivate the nickel oxide material in a gas atmosphere including carbon dioxide.

[0010] Optionally, the passivation treatment time is 4 to 10 minutes.

[0011] Optionally, depositing the nickel oxide material onto the first surface includes: depositing the nickel oxide material onto the first surface using a magnetron sputtering method.

[0012] According to another aspect of the present invention, a nickel oxide thin film is provided, which is prepared by using the above-mentioned method for preparing the nickel oxide thin film.

[0013] According to another aspect of the present invention, there is provided a method for preparing a perovskite solar cell, comprising: providing a transparent conductive substrate having a nickel oxide thin film, wherein the nickel oxide thin film is prepared by the method for preparing the nickel oxide thin film as described above; sequentially forming a perovskite absorption layer, an electron transport layer and an electrode layer on a side of the nickel oxide thin film away from the transparent conductive substrate; wherein the perovskite absorption layer is located on a side of the nickel oxide thin film away from the transparent conductive substrate, the electron transport layer is located on a side of the perovskite absorption layer away from the nickel oxide thin film, and the electrode layer is located on a side of the electron transport layer away from the perovskite absorption layer.

[0014] Optionally, after the step of forming the electron transport layer and before the step of forming the electrode layer, the preparation method further includes: forming a buffer layer on a side of the electron transport layer away from the perovskite absorption layer, so that the buffer layer is located between the electron transport layer and the electrode layer.

[0015] According to another aspect of the present invention, a perovskite solar cell is provided, which is prepared by the above-mentioned method for preparing a perovskite solar cell.

[0016] According to another aspect of the present invention, there is provided a stacked cell, comprising a first solar cell and a second solar cell which are stacked, wherein at least one of the first solar cell and the second solar cell comprises a perovskite solar cell as described above, and the first solar cell and the second solar cell have different band gap widths.

[0017] The technical solution of the present invention is applied to provide a method for preparing a nickel oxide thin film, which can make the Ni in the nickel oxide material be heated by heat-treating the nickel oxide material deposited on the transparent conductive substrate in a humid atmosphere. 3+ Reacts with H2O in the air to generate Ni 2+ , which regulates the Ni 3+ content, thereby improving the optical transmittance of the nickel oxide film, and promoting the crystallization of nickel oxide to improve the hole mobility. In addition, by passivating the surface of the nickel oxide material, the defect state and hydroxyl content on the surface of the nickel oxide can be reduced. Therefore, compared with the nickel oxide film that has not been heat-treated and passivated, after heat treatment and passivation treatment, the conductivity and film quality of the nickel oxide film are significantly improved, thereby solving the problem of poor conductivity and film quality of the nickel oxide film in the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 The figure shows the influence of annealing humidity on the conversion efficiency of a solar cell including the nickel oxide thin film in a method for preparing the nickel oxide thin film according to an embodiment of the present invention;

[0020] Figure 2 The figure shows the influence of the passivation time on the conversion efficiency of a solar cell including the nickel oxide thin film in the method for preparing the nickel oxide thin film according to an embodiment of the present invention;

[0021] Figure 3 A schematic cross-sectional structure diagram of a perovskite solar cell according to an embodiment of the present invention is shown;

[0022] Figure 4 The optical transmittance of the nickel oxide film according to an embodiment of the present invention in different wavelength ranges is shown;

[0023] Figure 5 The current density of the semi-transparent perovskite solar cell formed by the nickel oxide thin film according to the embodiment of the present invention at different voltages is shown;

[0024] Figure 6 The normalized efficiency of the device formed by the nickel oxide thin film according to the embodiment of the present invention during the storage time of 1200 hours is shown.

[0025] The above drawings include the following reference numerals:

[0026] 10. Transparent conductive substrate; 20. Nickel oxide film; 30. Perovskite absorption layer; 40. Electron transport layer; 50. Buffer layer; 60. Electrode layer; 601. Transparent conductive oxide layer; 602. Metal layer. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] As described in the background art, NiO x The hole transport layer has the following main disadvantages: the first is NiO x The interface contact between the NiO film and the perovskite film is poor, which is not conducive to the growth of high-quality perovskite films and may produce certain interface defects. x The conductivity of the film is not good enough, which limits the improvement of the short-circuit current (Jsc) of the perovskite solar cell based on the nickel oxide hole transport layer. In order to solve the above technical problems, the present application provides a method for preparing a nickel oxide film, a nickel oxide film, a method for preparing a perovskite solar cell, and a perovskite solar cell.

[0031] According to the first aspect of the present application, a method for preparing a nickel oxide thin film is provided. The method comprises: providing a transparent conductive substrate, the transparent conductive substrate having a first surface; depositing a nickel oxide material on the first surface; performing a heat treatment and a passivation treatment on the nickel oxide material deposited on the first surface to form a nickel oxide thin film, wherein the heat treatment is performed in a humid atmosphere.

[0032] In a specific embodiment, the method for preparing the nickel oxide thin film can be: providing a transparent conductive substrate having a first surface, depositing a nickel oxide material on the first surface of the transparent conductive substrate, first heat-treating the nickel oxide material, wherein the heat treatment is performed in a humid atmosphere, and then passivating the nickel oxide material after the heat treatment to form a nickel oxide thin film.

[0033] In another specific embodiment, the method for preparing the nickel oxide thin film can also be: providing a transparent conductive substrate having a first surface, depositing a nickel oxide material on the first surface of the transparent conductive substrate, first passivating the nickel oxide material, and then heat-treating the nickel oxide material after the passivation treatment, wherein the heat treatment is carried out in a humid atmosphere.

[0034] Usually, nickel oxide materials contain Ni 3+ , but too much Ni 3+ The conductivity of the nickel oxide film is reduced. Therefore, in the method for preparing the nickel oxide film of the present application, in order to improve the conductivity of the nickel oxide film, the nickel oxide material deposited on the transparent conductive substrate is heat-treated in a humid atmosphere so that the Ni in the nickel oxide material is 3+ Reacts with H2O in the air to generate Ni 2+ , thereby adjusting the Ni 3+ content, thereby improving the optical transmittance of the nickel oxide film and promoting the crystallization of nickel oxide to improve the hole mobility.

[0035] In addition, by passivating the surface of the nickel oxide material, the defect states and hydroxyl content on the surface of the nickel oxide can be reduced. Therefore, compared with the nickel oxide film that has not been heat-treated and passivated, the conductivity and film quality of the nickel oxide film are significantly improved after the heat treatment and passivation treatment, thereby solving the problem of poor conductivity and film quality of the nickel oxide film in the present application.

[0036] Optionally, before the step of depositing the nickel oxide material onto the first surface, the preparation method further comprises cleaning the transparent conductive substrate to remove impurities and dirt on the first surface of the transparent conductive substrate to ensure that the first surface is flat and dry.

[0037] Optionally, the material of the transparent conductive substrate may include but is not limited to any one or more of indium tin oxide (ITO, In2O3: Sn), aluminum-doped zinc oxide (AZO, ZnO: Al), fluorine-doped tin oxide (FTO, SnO2: F) and antimony-doped tin oxide (ATO, SnO2: Sb). Those skilled in the art may make reasonable selections based on actual needs, and no specific limitations are made in this application.

[0038] In a specific embodiment, the transparent conductive substrate may be an indium tin oxide substrate. Before depositing the nickel oxide material on the indium tin oxide substrate, the substrate may be ultrasonically cleaned for 20 minutes using detergent, deionized water, acetone, anhydrous ethanol and isopropanol in sequence, and dried in a vacuum drying oven at 80° C., and finally the cleaned and dried indium tin oxide substrate may be subjected to a plasma surface treatment for 10 minutes.

[0039] Specifically, the deposition process of the nickel oxide material may include but is not limited to physical vapor deposition and chemical vapor deposition.

[0040] Illustratively, the above-mentioned physical vapor deposition may include but is not limited to evaporation and magnetron sputtering.

[0041] Specifically, in the step of depositing the nickel oxide material on the first surface by magnetron sputtering, the transparent conductive substrate can be placed in the chamber of the magnetron sputtering coating instrument first, and then the vacuum step can be performed so that the air pressure in the chamber of the magnetron sputtering coating instrument meets the first preset air pressure, and then the first gas of the first preset flow rate is introduced, and the air pressure in the chamber of the magnetron sputtering coating instrument is controlled to the second preset air pressure and the temperature in the chamber of the magnetron sputtering coating instrument is controlled to be at the preset temperature. After that, the second gas of the second preset flow rate can be introduced, and the sputtering power of the magnetron sputtering coating instrument is set to the first preset value, and after the pre-sputtering for the first preset time, the substrate baffle of the transparent conductive substrate is opened, and the deposition of the nickel oxide material for the second preset time is started on the first surface of the transparent conductive substrate. It should be noted that the first preset air pressure, the first preset flow rate, the first gas, the second preset air pressure, the preset temperature, the second preset flow rate, the second gas, the first preset value, the first preset time and the second preset time can all be reasonably set according to the actual needs of those skilled in the art, and this application does not make specific limitations.

[0042] For example, the first preset air pressure may be 1×10 -4Pa, the first preset flow rate may be 75 sccm, the first gas may be high-purity argon, the second preset pressure may be 0.45 Pa, the preset temperature may be room temperature, the second preset flow rate may be 0.4 sccm, the second gas may be high-purity oxygen, the first preset value may be 60 W, the first preset time may be 1 min, and the second preset time may be 300 s.

[0043] In the above embodiment, by adopting the magnetron sputtering method, continuous, stable and large-scale nickel oxide thin material can be deposited on the transparent conductive substrate, and because the sputtering environment of the magnetron sputtering process is in the closed vacuum chamber of the magnetron sputtering coater, it can isolate the interference of the external environment on the deposition process of the nickel oxide material, thereby providing a good foundation for the formation of the nickel oxide thin film, so that the prepared nickel oxide thin film has good repeatability and adjustability.

[0044] In some optional embodiments, the nickel oxide material deposited on the first surface is subjected to heat treatment, comprising: placing the transparent conductive substrate in a first container to perform heat treatment on the nickel oxide material, wherein the humidity in the first container is 20 to 45%. Further, in order to more significantly improve the hole mobility of the nickel oxide film, the humidity in the first container can be 30 to 40%.

[0045] Specifically, the first container is used to provide a humid atmosphere for the heat treatment of the nickel oxide material, and in order to enable the nickel oxide material to be heat treated in the first container, the first container has a heating platform, and the heating platform is used to place the object to be heat treated (nickel oxide material). Exemplarily, the first container can be a glove box.

[0046] In the above embodiment, when the humidity in the first container is 20-45%, it can be used to provide a humidity environment for the heat treatment of the nickel oxide material. Then, when the transparent conductive substrate with the nickel oxide material deposited thereon is placed on the heating table in the above first container, and the temperature of the above heating table is adjusted to heat the nickel oxide material for a preset time, since the air in the humidity environment contains more H2O, the Ni in the nickel oxide material 3+ Reacting with H2O in the air can generate Ni 2+ Therefore, the heat treatment in this humidity environment regulates the Ni 3+ The content of nickel oxide increases the optical transmittance of nickel oxide film, promotes nickel oxide crystallization and improves hole mobility. And by controlling the humidity at 20-45%, the conductivity of nickel oxide film and the optical transmittance of nickel oxide film can be further balanced.

[0047] For example, Figure 1 As shown, Figure 1During the annealing process, on the basis of the heat treatment temperature of 200°C, the humidity in the first container is controlled to be untreated, 20% humidity, 30% humidity, 40% humidity and 50% humidity, and the conversion efficiency of the obtained multiple nickel oxide films after being applied to solar cells (multiple different humidity corresponds to multiple different solar cells one by one, and the difference between the multiple different solar cells is only the different heat treatment humidity for forming the nickel oxide film). Figure 1 It can be seen that by controlling the humidity in the first container to be within the range of 30% to 40% during the annealing process of the nickel oxide material and performing heat treatment, the conversion efficiency of the solar cell can be further significantly improved.

[0048] In some optional embodiments, the temperature of the heat treatment may be 100-200° C., and the time of the heat treatment may be 20-60 min.

[0049] Specifically, when the nickel oxide material is in a humid atmosphere, in order to improve the purity and stability of nickel oxide in the nickel oxide film after heat treatment, the heat treatment temperature of the nickel oxide material can be set between 100 and 200° C., and the heat treatment time can be set between 20 and 60 minutes.

[0050] In some optional embodiments, the nickel oxide material deposited on the first surface is passivated, including: using a glow discharge plasma treatment technique to passivate the nickel oxide material in a gas atmosphere including carbon dioxide. Exemplarily, the passivation treatment time may be 4 to 10 minutes.

[0051] For example, Figure 2 As shown, Figure 2 Based on the heat treatment temperature of 200°C and humidity annealing controlled at 35% in the first container, the nickel oxide material is passivated using the above-mentioned glow discharge plasma treatment technology, and multiple nickel oxide thin films obtained with passivation treatment times of 0min, 3min, 6min, 9min and 12min are applied to solar cells (multiple different passivation times correspond to multiple different solar cells one by one, and the difference between the multiple different solar cells is only the different passivation treatment times for forming the nickel oxide thin films). Figure 2It can be seen that by using the glow discharge plasma treatment technology to passivate the nickel oxide material in a gas atmosphere including carbon dioxide, the conversion efficiency of the solar cell can be further significantly improved. Specifically, the carbon dioxide gas can be first introduced into a glow discharge plasma device, and the carbon dioxide gas can be ionized by the glow discharge plasma treatment technology in the glow discharge plasma device to form carbon dioxide plasma, and then when the nickel oxide material is located in the glow discharge plasma device, the carbon dioxide plasma reacts with the surface of the nickel oxide material to achieve surface passivation treatment.

[0052] According to the second aspect of the present application, the applicant also provides a nickel oxide thin film, wherein the nickel oxide thin film can be prepared by using the above-mentioned method for preparing the nickel oxide thin film.

[0053] That is, for the nickel oxide film, since the nickel oxide film is prepared by the method for preparing the nickel oxide film of the present application, the Ni in the nickel oxide film is 3+ and Ni 2+ The content of is appropriate, so that the conductivity and optical transmittance of the nickel oxide film are significantly improved compared with the nickel oxide film in the prior art, and because the nickel oxide film has also been passivated, the defect state and hydroxyl content on the surface of the nickel oxide film are less, so it has better film quality than the nickel oxide film in the prior art. In summary, the nickel oxide film in the present application has been significantly improved in conductivity, optical transmittance and film quality compared with the nickel oxide film in the prior art.

[0054] According to the third aspect of the present application, the applicant also provides a method for preparing a perovskite solar cell. Specifically, the method for preparing the perovskite solar cell may include: providing a transparent conductive substrate having a nickel oxide film, wherein the nickel oxide film is prepared by the above-mentioned method for preparing the nickel oxide film; sequentially forming a perovskite absorption layer, an electron transport layer and an electrode layer on the side of the nickel oxide film away from the transparent conductive substrate; wherein the perovskite absorption layer is located on the side of the nickel oxide film away from the transparent conductive substrate, the electron transport layer is located on the side of the perovskite absorption layer away from the nickel oxide film, and the electrode layer is located on the side of the electron transport layer away from the perovskite absorption layer.

[0055] Specifically, the nickel oxide film in the perovskite solar cell can be prepared by the method for preparing the nickel oxide film of the present application, or can be directly provided, which will not be described in detail here. However, it should be noted that when the nickel oxide film in the perovskite solar cell of the present application is obtained by directly providing, the nickel oxide film provided should be a nickel oxide film prepared by the method for preparing the nickel oxide film of the present application.

[0056] Specifically, when the perovskite absorption layer is formed on the side of the nickel oxide film away from the semiconductor substrate, the deposition process of the perovskite absorption layer can be obtained by one-step deposition or step-by-step deposition. The one-step deposition process can be carried out with reference to the prior art and will not be described in detail here.

[0057] Exemplarily, in the process of forming the above-mentioned perovskite absorption layer by a step-by-step deposition process, the above-mentioned perovskite absorption layer can be prepared by a two-step spin coating method. Specifically, the metal halide can be first dissolved in a first organic solvent to obtain a first perovskite precursor solution. In addition, the organic amine salt can be dissolved in a second organic solvent to obtain a second perovskite precursor solution. Then, the first spin coating step can be performed, that is, the first perovskite precursor solution is dissolved and spin-coated to the surface of the side of the nickel oxide film away from the transparent conductive substrate, and after the first perovskite precursor solution is formed into a metal halide film, the second spin coating step is performed, that is, the second perovskite precursor solution is spin-coated to the surface of the side of the metal halide film away from the nickel oxide film, and then annealing can be used to form the above-mentioned perovskite absorption layer.

[0058] Wherein, the metal halide may be lead iodide (PbI2), the first organic solvent may be a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and the first perovskite precursor solution may be a lead iodide (PbI2) precursor solution. The organic amine salt may include formaldehyde iodide (FAI), methylammonium iodide (MAI) and methylammonium chloride (MACl), and the second organic solvent may be isopropanol, and the second perovskite precursor solution may be a mixed solution of formaldehyde iodide (FAI), methylammonium iodide (MAI) and methylammonium chloride (MACl).

[0059] Specifically, after the perovskite absorption layer is formed, the electron transport layer may be formed on a side of the perovskite absorption layer away from the nickel oxide film by using a vacuum evaporation method.

[0060] In addition, the material of the electron transport layer may include but is not limited to fullerene (C 60 ) and its derivatives, [6,6]-phenyl C 71 At least one of methyl butyrate (PCBM), tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB), zinc oxide and titanium dioxide. And the deposition process of the electron transport layer or the deposition process of the hole transport layer may also include but is not limited to evaporation, vacuum sputtering and reactive plasma deposition (RPD). Specifically, after forming the above-mentioned electron transport layer, an atomic layer deposition process can be used to form an electrode layer on the side of the above-mentioned electron transport layer away from the perovskite absorption layer.

[0061] In addition, the material of the electrode layer may include but is not limited to at least one of a transparent conductive oxide layer and a metal layer, and the formation process of the electrode layer may also include but is not limited to a magnetron sputtering method or a vacuum evaporation method.

[0062] In some optional embodiments, the method for preparing a perovskite solar cell may further include: after the step of forming an electron transport layer and before the step of forming an electrode layer, forming a buffer layer on a side of the electron transport layer away from the perovskite absorption layer, so that the buffer layer is located between the electron transport layer and the electrode layer.

[0063] In the above embodiment, the buffer layer can be formed on the side of the electron transport layer away from the perovskite absorption layer by an atomic layer deposition process. Exemplarily, the material of the buffer layer can be tin oxide. The buffer layer can improve the electron mobility and prevent damage to the electron transport layer during the electrode manufacturing process.

[0064] According to the fourth aspect of the present application, the applicant of the present application also provides a perovskite solar cell, such as Figure 3 As shown, the perovskite solar cell can be prepared by using the above-mentioned method for preparing a perovskite solar cell.

[0065] Specifically, in some optional embodiments, a perovskite solar cell may include a transparent conductive substrate 10, a nickel oxide thin film 20, a perovskite absorption layer 30, an electron transport layer 40 and an electrode layer 60 that are stacked. Further, in other optional embodiments, the perovskite solar cell may also include a buffer layer 50, which may be located between the electron transport layer 40 and the electrode layer 60. The electrode layer 60 may include at least one of a transparent conductive oxide layer 601 and a metal layer 602.

[0066] Exemplarily, when the perovskite solar cell includes a buffer layer 50 and the electrode layer 60 includes a transparent conductive oxide layer 601 and a metal layer 602, the transparent conductive oxide layer 601 is located on a side of the buffer layer 50 away from the electron transport layer 40, and the metal layer 602 is located on a side of the transparent conductive oxide layer 601 away from the buffer layer 50.

[0067] According to the fifth aspect of the present application, the applicant of the present application also provides a stacked cell, which may include a first solar cell and a second solar cell arranged in a stacked manner, at least one of the first solar cell and the second solar cell is the above-mentioned perovskite solar cell, and the first solar cell and the second solar cell have different band gap widths.

[0068] Specifically, the first solar cell may be a crystalline silicon cell, and the second perovskite solar cell may be prepared by the method for preparing a perovskite solar cell of the present application. Or both the first solar cell and the second solar cell may be prepared by the method for preparing a perovskite solar cell of the present application, but the first solar cell may have a first band gap, and the second solar cell may have a second band gap, and the first band gap is greater than or less than the second band gap.

[0069] In summary, since the Ni in the nickel oxide film of the present application 3+ and Ni 2+ The content of is appropriate, the conductivity and optical transmittance of the nickel oxide film are significantly improved compared with the nickel oxide film in the prior art, and because the nickel oxide film is also passivated, the defect state and hydroxyl content on the surface of the nickel oxide film are less, so that the nickel oxide film has better film quality than the nickel oxide film in the prior art, and after the nickel oxide film is applied to the perovskite solar cell or the stacked perovskite solar cell, the photoelectric conversion efficiency of the single-junction perovskite solar cell or the stacked perovskite solar cell with the nickel oxide film is significantly improved. In addition, in the case of the nickel oxide film of the present application, the single-junction perovskite solar cell or the stacked perovskite solar cell of the present application can also reduce the recombination of carriers, and can significantly inhibit the decomposition of perovskite in the single-junction perovskite solar cell or the stacked perovskite solar cell, thereby significantly improving the long-term stability of the perovskite solar cell. In addition, since the stacked perovskite solar cell can absorb more sunlight than the single-junction perovskite solar cell, the stacked perovskite solar cell has a higher photoelectric conversion efficiency than the single-junction perovskite solar cell.

[0070] The perovskite solar cell formed by the preparation method of the perovskite solar cell of the present invention will be further described below in combination with examples and comparative examples.

[0071] Example 1

[0072] S1. Provide an ITO glass substrate;

[0073] S2, sequentially using detergent, deionized water, acetone, anhydrous ethanol, and isopropanol for ultrasonic cleaning for 20 minutes each, and drying in a vacuum drying oven at 80°C, and finally performing plasma surface treatment on the cleaned and dried ITO substrate for 10 minutes;

[0074] S3, place the ITO substrate into the chamber of the magnetron sputtering coating instrument and evacuate to 1×10 -4Pa, 75 sccm of high-purity argon gas was introduced, the pressure in the chamber was controlled to be about 0.45 Pa, and the chamber temperature was room temperature. 0.4 sccm of high-purity oxygen was introduced and the sputtering power was set to 60 W. After pre-sputtering for 1 min, the substrate baffle was opened to start thin film deposition. The sputtering time was 300 s to deposit nickel oxide material on the surface of the ITO substrate. The thickness of the nickel oxide material was 20 nm.

[0075] S4. After the nickel oxide material is deposited, it is transferred to a heating table in an air glove box. The temperature of the heating table is set at 200°C, the annealing time is 30 minutes, and the humidity of the glove box is controlled at 35%;

[0076] S5. After annealing is completed, a room temperature glow discharge plasma treatment technology is used to generate CO2 plasma to perform etching and passivation treatment on the surface of the nickel oxide material for 6 minutes to form a nickel oxide film;

[0077] S6. Weigh 461.01 mg of PbI2 and dissolve it in 1 ml of a mixed solvent of DMF and DMSO (VDMF: VDMSO = 9:1) to obtain a PbI2 precursor solution with a concentration of 1.3 mol / ml. Weigh 60 mg of FAI, 6 mg of MAI and 6 mg of MACl and dissolve them in 1 ml of isopropanol to obtain an organic salt solution. Take 50 ul of the PbI2 precursor solution and evenly coat it on the NiO x On the hole transport layer, spin coating was performed at a speed of 1500 rpm / min for 30 seconds. After the spin coating was completed, the sample was quickly transferred to a heating table for annealing at 70°C for 1 minute to form a PbI2 film. Then, 50 μl of organic salt solvent was evenly coated on PbI2 and spin coated at a speed of 1600 rpm / min for 30 seconds. After the spin coating was completed, annealing was performed on a heating table at a temperature of 150°C for 15 minutes. During the annealing process, the sample environment humidity was kept at about 40%;

[0078] S7, using vacuum evaporation method to prepare C with a thickness of 20nm on the perovskite absorption layer 60 Electron transport layer;

[0079] S8, using atomic layer deposition method in C 60 A SnO2 buffer layer with a thickness of 20 nm is prepared on the electron transport layer;

[0080] S9, preparing an IZO transparent electrode with a thickness of 110 nm on the SnO2 buffer layer by magnetron sputtering;

[0081] S10. Prepare an Ag electrode with a thickness of 80 nm on the IZO transparent electrode by vacuum evaporation.

[0082] Comparative Example 1

[0083] Compared with the first embodiment, there is no step S4 and step S5.

[0084] Comparative Example 2

[0085] Compared with Embodiment 1, there is no step S5.

[0086] The nickel oxide thin films obtained in Comparative Examples 1 and 2 were tested for carrier mobility, carrier concentration and resistivity, and the test results shown in Table 1 were obtained:

[0087] Table 1

[0088]

[0089] As shown in Table 1, under 200℃ humidity annealing, due to the nickel oxide film (NiO x ) 3+ Can react with H2O in the air to generate Ni 2+ , which slightly reduces the carrier concentration, but due to Ni 3+ The reduction of NiO x The optical transmittance of NiO was improved by 200℃ humidity annealing. x crystallization, thereby improving the hole mobility of nickel oxide film, and finally making nickel oxide film (NiO x )’s electrical performance is significantly improved.

[0090] After the nickel oxide thin films obtained in Example 1, Comparative Example 1 and Comparative Example 2 are applied to perovskite solar cells (the difference between the three perovskite solar cells corresponding to Example 1, Comparative Example 1 and Comparative Example 2 is only the difference in the nickel oxide thin films), the electrical properties of the perovskite solar cells corresponding to the above Example 1, Comparative Example 1 and Comparative Example 2 are tested, and the test results shown in Table 2 are obtained:

[0091] Table 2

[0092]

[0093] As shown in Table 2, after annealing at 200°C in air for 30 minutes, the open circuit voltage and short circuit current density of the corresponding perovskite solar cell increased significantly. After further CO2 plasma treatment, the fill factor of the perovskite solar cell was improved. Finally, compared with untreated NiOx, after annealing at 200°C and CO2 plasma treatment of NiOx, the PCE of the corresponding perovskite solar cell increased from 12.43% to 15.44%.

[0094] Furthermore, if Figure 4 , Figure 5 and Figure 6 As shown, Figure 4The optical transmittance of the nickel oxide thin films obtained in Example 1, Comparative Example 1 and Comparative Example 2 under different wavelength ranges is shown. Figure 4 It can be seen that NiO x After annealing at 200℃ in air for 30min, the optical transmittance increased significantly, and the average optical transmittance in the wavelength range of 300-900nm increased from 68.49% to 74.08%. x The optical transmittance is almost not affected; Figure 5 The nickel oxide thin films obtained in Example 1, Comparative Example 1 and Comparative Example 2 are applied to semi-transparent perovskite solar cells (the difference between the three semi-transparent perovskite solar cells corresponding to Example 1, Comparative Example 1 and Comparative Example 2 is only the difference in the nickel oxide thin films), and the current density of the semi-transparent perovskite solar cells obtained by testing at different voltages is shown. Figure 5 It can be seen that after annealing at 200℃ in air for 30min, the open circuit voltage and short circuit current density of the corresponding semi-transparent perovskite solar cells are significantly improved. After further treatment with CO2 plasma, the filling factor of the semi-transparent perovskite solar cells is improved. Finally, compared with the untreated NiO x In comparison, NiO was annealed at 200°C and treated with CO2 plasma. x After that, the PCE of the corresponding semi-transparent perovskite solar cell increased from 12.43% to 15.44%; Figure 6 The normalized efficiency of the nickel oxide thin film obtained in Example 1, Comparative Example 1 and Comparative Example 2 is shown when the nickel oxide thin film is applied to a device (the difference between the three devices corresponding to Example 1, Comparative Example 1 and Comparative Example 2 is only the difference in the nickel oxide thin film) and placed for 1200 hours. Figure 6 It can be seen that the NiO was annealed at 200℃ and treated with CO2 plasma. x The device showed excellent stability, maintaining 93.27% of the initial efficiency after 1200 hours, while the NiO based on untreated and air annealed at 200℃ x The device efficiencies decayed to 75.66% and 80.78% of the initial efficiencies, respectively.

[0095] After the nickel oxide thin films obtained in Example 1, Comparative Example 1 and Comparative Example 2 are applied to perovskite solar cells (the difference between the three perovskite solar cells corresponding to Example 1, Comparative Example 1 and Comparative Example 2 is only the difference in the nickel oxide thin films), the perovskite solar cells are tested by X-ray photoelectron spectroscopy (XPS) technology, and the test results shown in Table 3 are obtained:

[0096] Table 3

[0097]

[0098] Among them, the O1S (an energy level in X-ray photoelectron spectrometer) peak is fitted into three peaks with approximately Gaussian distribution, O M Peaks were assigned to O 2- ions bonded to Ni atoms, O V The peak is attributed to oxygen defect site, O H Peaks were assigned to O 2- Ionic hydroxyl bond. V / (O M +O V +O H ) area ratio represents the relative amount of oxygen defect sites, O H / (O M +O V +O H ) area ratio represents the relative amount of hydroxyl groups.

[0099] In addition, lower interface defect state density can reduce interface recombination, and fewer hydroxyl groups are beneficial to improving the stability of the perovskite absorber layer deposited thereon, as shown in Table 2:

[0100] After humidity annealing at 200℃, O V / (O M +O V +O H ) area ratio decreased from 19.3% to 16.1%, and further CO2 plasma treatment, O V / (O M +O V +O H ) area ratio decreased to 11.4%, indicating that NiO x The oxygen defect sites on the film surface continue to decrease.

[0101] After humidity annealing at 200℃, O V / (O M +O V +O H ) area ratio increased from 9.4% to 11.7%, indicating that NiO x The hydroxyl content on the film surface increased, while after CO2 plasma treatment, the corresponding ratio decreased to 4.1%, indicating that CO2 plasma treatment effectively reduced the NiO x The proportion of hydroxyl groups on the film surface.

[0102] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0103] 1. The present invention heat treats the nickel oxide material deposited on the transparent conductive substrate in a humid atmosphere to make the Ni 3+Reacts with H2O in the air to generate Ni 2+ , which regulates the Ni 3+ content, thereby improving the optical transmittance of the nickel oxide film, and promoting the crystallization of nickel oxide to improve the hole mobility. In addition, by passivating the surface of the nickel oxide material, the defect state and hydroxyl content on the surface of the nickel oxide can be reduced. Therefore, compared with the nickel oxide film that has not been heat-treated and passivated, after heat treatment and passivation treatment, the conductivity and film quality of the nickel oxide film are significantly improved, thereby solving the problem of poor conductivity and film quality of the nickel oxide film in the present application.

[0104] 2. When the nickel oxide film prepared by the above nickel oxide film preparation method is applied to the field of perovskite solar cells, the nickel oxide film can be used as a hole transport layer of the perovskite solar cell. 3+ and Ni 2+ The content is appropriate, so that the conductivity and optical transmittance of the nickel oxide film are significantly improved compared with the nickel oxide film in the prior art, thereby significantly improving the photoelectric conversion efficiency of the perovskite solar cell with the nickel oxide film, and because the nickel oxide film has also been passivated, the defect state and hydroxyl content on the surface of the nickel oxide film are less, so that compared with the nickel oxide film in the prior art, it has better film quality, can reduce the recombination of carriers, and can significantly inhibit the decomposition of perovskite in the perovskite solar cell, thereby significantly improving the long-term stability of the perovskite solar cell. Therefore, since the perovskite solar cell of the present application has a nickel oxide film prepared according to the preparation method of the nickel oxide film in the present application, compared with the perovskite solar cell in the prior art, the photoelectric conversion efficiency and long-term stability of the perovskite solar cell in the present application are significantly improved.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a nickel oxide thin film, characterized in that: include: Providing a transparent conductive substrate having a first surface; depositing nickel oxide material onto the first surface; The nickel oxide material deposited on the first surface is subjected to a heat treatment and a passivation treatment to form a nickel oxide thin film, wherein the heat treatment is performed in a humidity atmosphere.

2. The preparation method according to claim 1, characterized in that: The nickel oxide material deposited on the first surface is subjected to a heat treatment, comprising: The transparent conductive substrate is placed in a first container to perform the heat treatment on the nickel oxide material, and the humidity in the first container is 20-45%.

3. The preparation method according to claim 2, characterized in that: The temperature of the heat treatment is 100-200° C., and the time of the heat treatment is 20-60 minutes.

4. The preparation method according to claim 1, characterized in that: Passivating the nickel oxide material deposited on the first surface comprises: The passivation treatment is performed on the nickel oxide material in a gas atmosphere including carbon dioxide using a glow discharge plasma treatment technology.

5. The preparation method according to claim 4, characterized in that: The passivation treatment time is 4 to 10 minutes.

6. The preparation method according to any one of claims 1 to 5, characterized in that Depositing nickel oxide material onto the first surface comprises: The nickel oxide material is deposited on the first surface by using a magnetron sputtering method.

7. A nickel oxide thin film, characterized in that: The nickel oxide thin film is prepared by the method for preparing the nickel oxide thin film according to any one of claims 1 to 6.

8. A method for preparing a perovskite solar cell, characterized in that: include: A transparent conductive substrate having a nickel oxide thin film is provided, wherein the nickel oxide thin film is prepared by the method for preparing a nickel oxide thin film according to any one of claims 1 to 6; Sequentially forming a perovskite absorption layer, an electron transport layer and an electrode layer on a side of the nickel oxide film away from the transparent conductive substrate; The perovskite absorption layer is located on a side of the nickel oxide film away from the transparent conductive substrate, the electron transport layer is located on a side of the perovskite absorption layer away from the nickel oxide film, and the electrode layer is located on a side of the electron transport layer away from the perovskite absorption layer.

9. The preparation method according to claim 8, characterized in that: After the step of forming the electron transport layer and before the step of forming the electrode layer, the preparation method further comprises: A buffer layer is formed on a side of the electron transport layer away from the perovskite absorption layer, so that the buffer layer is located between the electron transport layer and the electrode layer.

10. A perovskite solar cell, characterized in that: The perovskite solar cell is prepared by the preparation method of claim 8 or 9.

11. A tandem perovskite solar cell, characterized in that: The invention comprises a first solar cell and a second solar cell which are stacked, wherein at least one of the first solar cell and the second solar cell comprises the perovskite solar cell according to claim 10, and the first solar cell and the second solar cell have different band gap widths.

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