Perovskite solar cell and preparation method thereof

Abstract

The invention relates to a perovskite solar cell and a preparation method thereof, the perovskite solar cell comprises a transparent conductive substrate, an electron transport layer and a perovskite layer which are connected in sequence, the electron transport layer is a tin oxide electron transport layer doped with MDACl2, and the mass ratio of tin oxide to MDACl2 is (10-30): 1. Therefore, MDACl2 is used as a dopant of tin oxide, the colloidal property of the electron transport layer can be adjusted, the deposition condition of the electron transport layer can be improved, and the interface contact between the electron transport layer and perovskite can be optimized; meanwhile, the oxygen vacancy defect of tin oxide is reduced through the dopant, the crystallization quality of the perovskite thin film is improved, the interface energy level arrangement is optimized, and the open-circuit voltage, the short-circuit current and the filling factor of the cell are improved, so that the perovskite solar cell with higher efficiency and better stability is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and particularly to a perovskite solar cell and a preparation method thereof. Background Art

[0002] In recent years, perovskite solar cells (PSCs) have witnessed rapid development in the photovoltaic field due to their excellent optoelectronic properties and scalable preparation methods. The perovskite structure used in photovoltaic devices is ABX3, where A is a monovalent cation such as FA + , MA + and Cs + , B is a divalent metal cation, such as Pb 2+ , Sn 2+ , X is a halogen ion, such as I - , Br - , Cl - . The excellent photovoltaic performance of PSCs is mainly attributed to the unique physical and chemical properties of metal halide perovskite materials. Currently, PSCs have achieved a certified photoelectric conversion efficiency (hereinafter referred to as efficiency) of over 26%. Reducing costs and improving stability are the main development directions of PSCs in the future.

[0003] A large number of defect states in the perovskite film and mismatched energy levels at the interface are the main reasons limiting performance improvement. The n-i-p type normal device usually includes the following structure: a transparent conductive substrate (TCO), an electron transport layer (ETL), a perovskite layer, a hole transport layer (HTL), and a metal electrode / carbon electrode. In the n-i-p type normal device, the buried interface refers to the contact interface between the electron transport layer and the perovskite, and the nature and quality of the interface directly affect the performance of the battery. Due to the lattice mismatch between the electron transport layer (SnO2) and the perovskite, the growth process of the perovskite on the electron transport layer is uneven, resulting in voids or inappropriate strain, thus bringing obvious defects and reducing the performance of the device. At the same time, the poor energy level matching between the electron transport layer and the perovskite also leads to a low separation and transport efficiency of photo-generated electrons, thereby reducing the photoelectric conversion efficiency of the device. In addition, photo-induced degradation has been proven to mainly occur at the buried interface, which obviously exacerbates the stability problem of perovskite solar cells. Based on this, studying the modification strategy of the tin oxide electron transport layer, improving the interface contact, and optimizing the energy level arrangement are of great significance for improving the efficiency and stability of perovskite photovoltaic devices.

[0004] In summary, the deficiencies of current perovskite solar cells based on SnO2 electron transport layers include the following aspects: (1) The structure of the current tin oxide electron transport layer lacks precise control, making it difficult to obtain an excellent contact interface, which limits the performance improvement of perovskite solar cells; (2) The tin oxide prepared by the spin-coating method contains a large number of oxygen vacancy defects, which is not conducive to the photoelectric conversion efficiency and working stability of the battery. Summary of the Invention

[0005] Based on this, it is necessary to provide a perovskite solar cell and its preparation method that can improve the contact interface between the electron transport layer and perovskite, improve oxygen vacancy defects, and increase the photoelectric conversion efficiency of the battery.

[0006] In a first aspect, the present application provides a perovskite solar cell, including a transparent conductive substrate, an electron transport layer, and a perovskite layer connected in sequence. The electron transport layer is a tin oxide electron transport layer doped with MDACl2, where the mass ratio of tin oxide to MDACl2 is "10 - 30":1.

[0007] In one embodiment, the mass ratio of tin oxide to MDACl2 is "10 - 15":1.

[0008] In one embodiment, the component of the perovskite layer is FA 0.95 Cs 0.05 PbI3. Of course, the component of the perovskite layer in the present application can also be the component structure of other perovskite layers in the art.

[0009] In one embodiment, the material of the transparent conductive substrate is fluorine-doped tin oxide.

[0010] In one embodiment, the preparation method of the electron transport layer includes the following steps: Dilute the tin oxide colloidal solution with deionized water to 3%, then add MDACl2 at a concentration of 1 - 3 mg / mL, mix well, and spin-coat the tin oxide colloidal liquid on the transparent conductive substrate. After annealing treatment, the electron transport layer is prepared.

[0011] In one embodiment, during the preparation of the electron transport layer, the addition concentration of MDACl2 is 2 mg / mL.

[0012] In a second aspect, the present application provides a preparation method of a perovskite solar cell as described in any of the above embodiments, including the following steps:

[0013] Provide a transparent conductive substrate;

[0014] Form an electron transport layer on the transparent conductive substrate;

[0015] Form the perovskite layer on the electron transport layer;

[0016] A commercial carbon paste is scrape-coated on the perovskite layer to form an electrode.

[0017] In one embodiment, the perovskite layer is prepared on the electron transport layer by a two-step method.

[0018] In one embodiment, the composition of the perovskite layer is FA 0.95 Cs 0.05 PbI3.

[0019] In one embodiment, before forming the electron transport layer, the transparent conductive substrate is subjected to cleaning and ozone treatment operations.

[0020] For the perovskite solar cell provided in this application, by doping MDACl2 (Methylenediammonium Dichloride) in the electron transport layer, where the mass ratio of tin oxide to MDACl2 is "10 - 30":1. In this way, the tin oxide electron transport layer doped with MDACl2 can improve the open-circuit voltage, short-circuit current density and fill factor of the carbon-based perovskite solar cell, and ultimately significantly improve the cell efficiency. Especially when the mass ratio of tin oxide to MDACl2 is "10 - 30":1, the open-circuit voltage of the carbon-based perovskite solar cell can be increased to more than 1.03, the fill factor can be increased to more than 74.18%, and the photoelectric conversion rate can be increased to more than 17.79%. For the perovskite solar cell of this application, using MDACl2 as the dopant of tin oxide can adjust the colloidal properties of the electron transport layer, improve the deposition of the electron transport layer, optimize the interface contact between the electron transport layer and the perovskite; at the same time, the present invention reduces the oxygen vacancy defects of tin oxide through this dopant, improves the crystallization quality of the perovskite thin film, optimizes the interface energy level arrangement, improves the open-circuit voltage, short-circuit current and fill factor of the cell, thereby obtaining a perovskite solar cell with higher efficiency and better stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a voltage-current curve graph for testing the optoelectronic performance of the perovskite solar cell device according to an embodiment of the present invention;

[0022] Figure 2 It is a structural schematic diagram of a perovskite solar cell according to an embodiment;

[0023] Figure 3 It is a process schematic diagram of a method for preparing a perovskite thin film at low temperature according to an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] For the convenience of understanding the present invention, in order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention, and the preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0025] In a first aspect, the present application provides a perovskite solar cell, which includes a transparent conductive substrate, an electron transport layer, and a perovskite layer connected in sequence. The electron transport layer is an electron transport layer of tin oxide doped with MDACl2, and the mass ratio of tin oxide to MDACl2 is "10-30":1.

[0026] For example, as Figure 2 shown, the perovskite solar cell includes a transparent conductive substrate (FTO / ITO), an electron transport layer (ETL), a perovskite layer, and a metal electrode / carbon electrode. The transparent conductive substrate is usually made of FTO or ITO. The transparent conductive substrate serves as a photoanode substrate and usually uses fluorine-doped tin oxide (FTO) or indium-doped tin oxide (ITO) coated glass, and its function is to transmit light and collect current. The electron transport layer (ETL) usually uses tin oxide (SnO2) colloid to form a dense film on the surface of the substrate through a coating process. As a component of the electron transport layer, it promotes the transport of photo-generated electrons to the conductive substrate and simultaneously optimizes the interfacial charge separation efficiency. Of course, it should be noted that Figure 2 the perovskite solar cell shown is only an example. It should be understood that the perovskite solar cell is not limited to the above structure and can also be other structures well known in the art. The present application mainly focuses on the improvement of the electron transport layer, and the electron transport layer in any other structure well known in the art can adopt the concept of the present application.

[0027] The perovskite solar cell provided by this application dopes MDACl2 (Methylenediammonium Dichloride) in the electron transport layer, where the mass ratio of tin oxide to MDACl2 is "10 - 30":1. In this way, the tin oxide electron transport layer doped with MDACl2 can improve the open-circuit voltage, short-circuit current density and fill factor of the carbon-based perovskite solar cell, and ultimately significantly improve the cell efficiency. In particular, when the mass ratio of tin oxide to MDACl2 is "10 - 30":1, the open-circuit voltage of the carbon-based perovskite solar cell can be increased to more than 1.03, the fill factor can be increased to more than 74.18%, and the photoelectric conversion rate can be increased to more than 17.79%. For the perovskite solar cell of this application, using MDACl2 as the dopant of tin oxide can adjust the colloidal properties of the electron transport layer, improve the deposition of the electron transport layer, and optimize the interfacial contact between the electron transport layer and the perovskite. At the same time, the present invention reduces the oxygen vacancy defects of tin oxide through this dopant, improves the crystallization quality of the perovskite thin film, optimizes the interfacial energy level arrangement, improves the open-circuit voltage, short-circuit current and fill factor of the cell, thereby obtaining a perovskite solar cell with higher efficiency and better stability.

[0028] In one of the embodiments, the preparation method of the electron transport layer includes the following steps: Dilute the tin oxide colloidal solution with deionized water to 3%, then add MDACl2 at a concentration of 1 - 3 mg / mL, mix well, and spin-coat the tin oxide colloidal liquid on a transparent conductive substrate, and prepare the electron transport layer after annealing treatment. It should be noted that after the mass concentration (mass / volume (w / v)) of the tin oxide colloidal solution is diluted to 3%, that is, 30 mg / mL (3 g / 100 mL), by adding MDACl2 at a concentration of 1 - 3 mg / mL, for 1 mL of the mixed solution:

[0029] The mass ratio of tin oxide to MDACl2 is:

[0030]

[0031] When the addition amount of MDACl2 is 1 mg / mL, then the mass ratio of tin oxide to MDACl2 is 30:1; when the addition amount of MDACl2 is 3 mg / mL, then the mass ratio of tin oxide to MDACl2 is 10:1; when the addition amount of MDACl2 is 2 mg / mL, then the mass ratio of tin oxide to MDACl2 is 15:1.

[0032] In one embodiment, the mass ratio of tin oxide to MDACl2 is "10-15":1. In this way, the open-circuit voltage, short-circuit current density and fill factor of the carbon-based perovskite solar cell can be further improved, and finally the cell efficiency can be significantly enhanced. Preferably, the mass ratio of tin oxide to MDACl2 is 15:1, so that the open-circuit voltage, short-circuit current density and fill factor of the carbon-based perovskite solar cell can be further improved.

[0033] In one embodiment, the component of the perovskite layer is FA 0.95 Cs 0.05 PbI3. In this way, the photoelectric conversion efficiency can be further improved. Of course, the component of the perovskite layer of the present application is not limited to this, and it can be other components of perovskite in the art.

[0034] In one embodiment, the material of the transparent conductive substrate is fluorine-doped tin oxide (FTO), and of course it can also be ITO (indium tin oxide), and preferably it is FTO.

[0035] In one embodiment, during the preparation process of the electron transport layer, the addition concentration of MDACl2 is 2 mg / mL. When 2 mg / mL is added, the mass ratio of tin oxide to MDACl2 is 15:1, so that the open-circuit voltage, short-circuit current density and fill factor of the carbon-based perovskite solar cell can be further improved. In particular, when 2 mg / mL is added, the photoelectric conversion efficiency can reach 18.97%, approaching an efficiency of 19%, which has obvious advantages in this field.

[0036] In a second aspect, the present application provides a method for preparing a perovskite solar cell as described in any one of the above embodiments, including the following steps:

[0037] Provide a transparent conductive substrate;

[0038] Form an electron transport layer on the transparent conductive substrate;

[0039] Form the perovskite layer on the electron transport layer;

[0040] Scrape and coat commercial carbon paste on the perovskite layer to form an electrode.

[0041] In one embodiment, before forming the electron transport layer, the transparent conductive substrate is cleaned and ozone-treated.

[0042] In one embodiment, an electron transport layer is formed on a transparent conductive substrate, including the following steps: 1. Preparation of an electron transport layer doped with MDACl2: Dilute the tin oxide colloidal solution with deionized water to 3%, then add MDACl2 at a concentration of 1-3 mg / mL, shake well and filter for standby. 2. Clean the FTO conductive glass and treat it with ozone for 15 minutes. 3. Set the rotation speed of the spin coater to 4000 rpm, take 50 μL of the prepared tin oxide colloidal solution and drop it on the FTO, start spin coating for 30 seconds, and then transfer it to a hot plate at 150 °C for annealing for 30 minutes. In this way, the electron transport layer can be prepared on the FTO.

[0043] In one embodiment, the perovskite layer is prepared on the electron transport layer by a two-step method. For example, the composition of the perovskite layer is FA 0.95 Cs 0.05PbI3. For example, the perovskite layer is prepared on the electron transport layer by a two-step method using a perovskite precursor solution, where the perovskite precursor solution includes solution A and solution B. Solution B includes the following components: lead iodide (PbI2), cesium chloride (CsCl), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); solution A includes the following components: formamidinium iodide (FAI), methylammonium chloride (MACl), and isopropyl alcohol (IPA); for example, the storage temperature of solution A is 0 to 20 degrees Celsius. Thus, by reducing the temperature of the precursor solution, adverse chemical reactions between perovskite components are inhibited, the crystallization quality of the perovskite film is improved, the usable time of the precursor solution is extended, the operation window is broadened, and at the same time, waste of the solution is reduced. For example, in solution B, the mass-volume ratio of lead iodide, cesium chloride, dimethylformamide, and dimethyl sulfoxide is 691 mg: 12.5 mg: 900 μL: 100 μL; again, solution B includes the following components in mass parts or volume parts: PbI2: 691 mg, CsCl: 12.5 mg, DMF: 900 μL, DMSO: 100 μL; for example, the storage temperature of solution A is 8 - 12 degrees Celsius, preferably, the storage temperature of solution A is 10 degrees Celsius. For example, in solution A, the mass-volume ratio of formamidinium iodide, methylammonium chloride, and isopropyl alcohol is 180 mg: 18 mg: 2 mL; for example, solution A includes the following components in mass parts or volume parts: FAI: 180 mg, MACl: 18 mg, IPA: 2 mL. Thus, by using solution A with the above components and mixing it with solution A stored at a relatively low temperature and using a two-step method to prepare the perovskite film, the crystallization quality of the perovskite film can be further improved, and the open-circuit voltage, short-circuit current, and fill factor of the carbon-based perovskite solar cell can also be further improved, thereby obtaining a perovskite solar cell with higher efficiency and better stability. At the same time, the precursor solution stored at a low temperature for a long time can still be used to prepare the battery without showing obvious performance degradation, which is more suitable for industrial large-scale production. Of course, it should be understood that solution A can also be stored at a temperature other than the above low temperature. As Figure 3 shown, it is a diagram of preparing the perovskite film at a low temperature. First, solution B is used to form a PbI2 layer on the electron transport layer, and then solution A is used to react on the PbI2 layer to form an FAI layer, and after the reaction, the perovskite film is prepared.

[0044] The perovskite solar cell provided by the present application dopes MDACl2 (methylenediammonium dichloride) in the electron transport layer, where the mass ratio of tin oxide to MDACl2 is "10 - 30":1. In this way, the tin oxide electron transport layer doped with MDACl2 can improve the open-circuit voltage, short-circuit current density and fill factor of the carbon-based perovskite solar cell, and finally significantly improve the cell efficiency. In particular, when the mass ratio of tin oxide to MDACl2 is "10 - 30":1, the open-circuit voltage of the carbon-based perovskite solar cell can be increased to more than 1.03, the fill factor can be increased to more than 74.18%, and the photoelectric conversion rate can be increased to more than 17.79%. For the perovskite solar cell of the present application, using MDACl2 as the dopant of tin oxide can adjust the colloidal properties of the electron transport layer, improve the deposition of the electron transport layer, and optimize the interfacial contact between the electron transport layer and the perovskite; at the same time, the present invention reduces the oxygen vacancy defects of tin oxide through this dopant, improves the crystallization quality of the perovskite thin film, optimizes the interfacial energy level arrangement, improves the open-circuit voltage, short-circuit current and fill factor of the cell, and thus obtains a perovskite solar cell with higher efficiency and better stability.

[0045] The following continues to illustrate the present application with specific examples.

[0046] Example 1

[0047] The preparation method of the perovskite solar cell includes the following steps:

[0048] 1. Preparation of tin oxide solution for the electron transport layer doped with MDACl2: Dilute the tin oxide colloidal solution with deionized water to 3%, then add MDACl2 at a concentration of 1 mg / mL, shake well and filter for standby. Note: When the addition amount of MDACl2 is 1 mg / mL, the mass ratio of tin oxide to MDACl2 is 30:1.

[0049] 2. Clean the FTO conductive glass and perform ozone treatment for 15 minutes.

[0050] 3. Set the rotation speed of the spin coater to 4000 rpm, take 50 μL of the prepared tin oxide colloidal solution and drop it on the FTO, start spin coating for 30 seconds, and then transfer it to a hot plate at 150 °C for annealing for 30 minutes, that is, an electron transport layer is formed on the FTO.

[0051] 4. The above-treated substrate is subjected to ozone treatment for 15 minutes and placed on a spin coater. The perovskite thin film is prepared by a two-step method, and the perovskite composition is FA 0.95 Cs 0.05 PbI3. After spin coating, anneal at 150 °C for 15 minutes.

[0052] 5. Apply commercial carbon paste by scraping on the prepared perovskite film above, and then anneal at 120 °C for 10 minutes to complete the preparation of the battery.

[0053] Example 2

[0054] Different from Example 1, in the preparation of the tin oxide solution of the electron transport layer doped with MDACl2, add MDACl2 at a concentration of 2 mg / mL. In this Example 2, when the addition amount of MDACl2 is 2 mg / mL, then the mass ratio of tin oxide to MDACl2 is 15:1.

[0055] Example 3

[0056] Different from Example 1, in the preparation of the tin oxide solution of the electron transport layer doped with MDACl2, add MDACl2 at a concentration of 3 mg / mL. In this example, when the addition amount of MDACl2 is 3 mg / mL, then the mass ratio of tin oxide to MDACl2 is 10:1.

[0057] Comparative Example 1

[0058] Different from Example 1, in the preparation of the tin oxide solution of the electron transport layer doped with MDACl2, MDACl2 was not added.

[0059] Perform optoelectronic performance tests on the prepared carbon-based perovskite solar cell devices of each example and comparative example, and obtain the voltage-current curve as Figure 1 , and the photoelectric conversion efficiency is shown in Table 1.

[0060] Table 1 Test results of optoelectronic performance tests of each example and comparative example

[0061]

[0062] According to Table 1 and Figure 1 It can be seen that compared with Comparative Example 1, the tin oxide electron transport layer doped with MDACl2 in Examples 1 to 3 can improve the open circuit voltage, short circuit current density and fill factor of the carbon-based perovskite solar cell, and ultimately significantly improve the battery efficiency. Among them, when the doping concentration of MDACl2 in tin oxide is 2.0 mg / mL, the carbon-based perovskite solar cell obtains the highest photoelectric conversion efficiency.

[0063] In this application, it is proposed to incorporate MDACl2 (methylene diaminodihydrochloride) into the tin oxide colloidal solution, which can improve the deposition state of the tin oxide colloid, optimize the interfacial contact between the perovskite and the electron transport layer, simultaneously improve the crystallization quality of the perovskite, and optimize the energy level alignment at the interface, thereby obtaining a perovskite solar cell with higher photovoltaic performance. The preparation method of the perovskite solar cell according to the present invention is as follows: (1) Prepare an MDACl2-SnO2 electron transport layer on FTO or ITO conductive glass; (2) Prepare a perovskite thin film on the electron transport layer; (3) Knife-coat conductive carbon paste on the perovskite thin film. Advantages and positive effects of the present invention: By using MDACl2 as a dopant for tin oxide, the present invention can adjust the colloidal properties of the electron transport layer, improve the deposition of the electron transport layer, and optimize the interfacial contact between the electron transport layer and the perovskite; at the same time, the present invention reduces the oxygen vacancy defects of tin oxide through this dopant, improves the crystallization quality of the perovskite thin film, optimizes the interfacial energy level alignment, and increases the open circuit voltage, short circuit current, and fill factor of the battery, thereby obtaining a perovskite solar cell with higher efficiency and better stability.

[0064] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification. It should be noted that "in one embodiment of the present application", "for example", "for another example", etc. in this application are intended to illustrate the present application, rather than to limit the present application. The above-described embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A perovskite solar cell, comprising a transparent conductive substrate, an electron transport layer, and a perovskite layer connected in sequence, characterized in that, The electron transport layer is a tin oxide electron transport layer doped with MDACl2, where the mass ratio of tin oxide to MDACl2 is "10 - 30":

1.

2. The perovskite solar cell according to claim 1, wherein The mass ratio of tin oxide to MDACl2 is "10 - 15":

1.

3. The perovskite solar cell according to claim 1, wherein The composition of the perovskite layer is FA 0.95 Cs 0.05 PbI3.

4. The perovskite solar cell according to claim 1, wherein The material of the transparent conductive substrate is fluorine-doped tin oxide.

5. The perovskite solar cell according to claim 4, wherein The preparation method of the electron transport layer includes the following steps: Dilute the tin oxide colloidal solution with deionized water to 3%, then add MDACl2 at a concentration of 1 - 3 mg / mL, mix well, and spin-coat the tin oxide colloidal liquid on the transparent conductive substrate. After annealing treatment, the electron transport layer is prepared.

6. The perovskite solar cell according to claim 1, characterized in that, During the preparation of the electron transport layer, the addition concentration of MDACl2 is 2 mg / mL; And / or, a carbon electrode layer is further connected to the side of the perovskite layer away from the electron transport layer.

7. A method for preparing a perovskite solar cell according to any one of claims 1 to 6, characterized in that, Including the following steps: Provide a transparent conductive substrate; Form an electron transport layer on the transparent conductive substrate; Form the perovskite layer on the electron transport layer; Scrape and coat commercial carbon paste on the perovskite layer to form an electrode.

8. The preparation method according to claim 7, characterized in that, The perovskite layer is prepared on the electron transport layer by a two-step method.

9. The preparation method according to claim 7, wherein The composition of the perovskite layer is FA 0.95 Cs 0.05 PbI3.

10. The preparation method according to claim 7, characterized in that, Before forming the electron transport layer, the transparent conductive substrate is cleaned and treated with ozone.

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