Method for preparing perovskite layer by anti-solvent method and perovskite optoelectronic device

Abstract

The application discloses a method for preparing a perovskite layer by using an anti-solvent method and a perovskite photoelectric device. The method comprises the following steps: providing a substrate and a perovskite precursor solution; coating an anti-solvent on the surface of the substrate to form a liquid film; coating the perovskite precursor solution on the liquid film and performing annealing treatment to form a perovskite layer. The perovskite photoelectric device comprises a hole transport layer, a perovskite layer and an electron transport layer which are sequentially stacked, and the perovskite layer is prepared by using the above method. The method for preparing the perovskite layer by using the anti-solvent method makes the crystallization of the perovskite start from the lower surface and then gradually transition to the upper surface, thereby avoiding the formation of holes at the bottom of the perovskite layer, improving the contact of the perovskite thin film and the substrate, and further improving the efficiency and stability of the perovskite device.

Description

Technical Field

[0001] This invention relates to the field of perovskite optoelectronic device technology, and in particular to a method for preparing a perovskite layer by an anti-solvent method and a perovskite optoelectronic device. Background Technology

[0002] In recent years, with the continuous deepening of research, perovskite solar cells have made rapid progress. The photoelectric conversion efficiency measured in the laboratory has increased from the initial 3.8% to more than 25%, and they are hailed as "new hope in the photovoltaic field".

[0003] Common perovskite solar cell structures include mesoscopic structures, mesoscopic superstructures, planar nip-type structures, and planar pin-type structures. Currently, the commonly used methods for preparing perovskite layers for small devices are two-step methods and one-step spin-coating methods.

[0004] like Figure 1 As shown, the existing one-step spin-coating method refers to a preparation method in which a perovskite precursor solution is spin-coated onto a substrate, and then most of the solvent is removed by antisolvent removal or degassing, allowing perovskite crystals to precipitate and crystallize to form a perovskite layer. Commonly used solvents for the perovskite precursor solution include, for example, a mixture of N,N-dimethylformamide and dimethyl sulfoxide.

[0005] However, the inventors have discovered that, using traditional processing techniques, whether the solvent removal method or the degassing method is used, the perovskite on the upper surface of the coated liquid film will crystallize first, while some solvents such as dimethyl sulfoxide will remain on the lower surface. Due to their non-volatile nature, the residual solvent will be gradually evaporated and removed during the subsequent annealing process, leaving many pores. These pores will cause problems in the contact between the perovskite layer and the substrate, and will make the device more prone to degradation and damage in the future, because water and oxygen in the air can more easily enter through the pores.

[0006] Therefore, avoiding the formation of pores during the formation of the perovskite layer is key to improving the performance of perovskite optoelectronic devices.

[0007] It should be noted that the information disclosed in the background section is only intended to enhance the understanding of the technical background of the present invention. It includes the inventors' exploration and analysis of the problems existing in the prior art, and should not be regarded as an admission or in any form implying that all the contents of the background section constitute prior art that is already known to those skilled in the art. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing perovskite layers using an anti-solvent method and a perovskite optoelectronic device.

[0009] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0010] In a first aspect, the present invention provides a method for preparing a perovskite layer using an anti-solvent method, comprising:

[0011] Provides substrate and perovskite precursor solution;

[0012] An anti-solvent is coated onto the substrate surface to form a liquid film;

[0013] The perovskite precursor solution is coated onto the liquid film and then annealed to form a perovskite layer.

[0014] Secondly, the present invention also provides a perovskite optoelectronic device, comprising a hole transport layer, a perovskite layer and an electron transport layer stacked sequentially, wherein the perovskite layer is prepared by the above method.

[0015] In the above technical solution, a novel method for preparing perovskite layers using anti-solvent preparation is proposed. This method allows the crystallization of perovskite to begin from the lower surface and then gradually transition to the upper surface, thereby avoiding the formation of pores at the bottom of the perovskite layer, improving the contact between the perovskite film and the substrate, and thus improving the efficiency and stability of perovskite devices.

[0016] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least the following:

[0017] The anti-solvent method for preparing perovskite layers provided by this invention can effectively avoid the formation of pores at the bottom of the perovskite layer during the crystallization process, enhance the contact between the perovskite layer and the substrate, and thus improve the efficiency and stability of perovskite devices.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a prior art process for preparing a perovskite layer using an anti-solvent method, as provided in the background art of this invention.

[0020] Figure 2a This is an electron microscope image of the cross-sectional morphology of a perovskite layer prepared by the anti-solvent method, provided in a typical comparative case of this invention;

[0021] Figure 2b This is an electron microscope image of the cross-sectional morphology of a perovskite layer prepared by the anti-solvent method, provided in a typical embodiment of the present invention;

[0022] Figure 3This is a comparative test diagram of the current-voltage characteristic curves of perovskite layers prepared by the anti-solvent method provided in a typical embodiment and a typical comparative case of the present invention;

[0023] Figure 4 This is a comparison chart of aging tests of perovskite devices provided in a typical embodiment and comparative case of the present invention. Detailed Implementation

[0024] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0026] Moreover, relational terms such as “first” and “second” are used merely to distinguish one component or method step from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components or method steps.

[0027] In existing technologies, the traditional process for preparing perovskite layers using anti-solvents is as follows:

[0028] Step 1: Prepare a 1.4M perovskite solution with N,N-dimethylformamide:dimethyl sulfoxide = 4:1 as the solvent, and spin-coat the perovskite precursor solution onto the substrate surface.

[0029] Step 2: During the spin coating process, add the anti-solvent dropwise at a suitable process time (generally about 10 seconds before the end of spin coating). The amount added is about 300 microliters. The anti-solvents used include chlorobenzene, ethyl acetate, and diethyl ether.

[0030] Step 3: Place the perovskite film on a heating plate for annealing at a temperature of about 120°C for about 30 minutes.

[0031] In the process of preparing perovskite layers using the anti-solvent method, the perovskite crystallization process starts from the top surface, and the residual solvent is "sealed" at the bottom. As the annealing process proceeds, the solvent at the bottom slowly evaporates, leaving many pores. These pores cause problems in the contact between the perovskite film and the substrate, affecting the device efficiency and the stability of subsequent devices.

[0032] To address this issue, we propose a novel anti-solvent preparation process. This process allows perovskite crystallization to begin from the lower surface and gradually transition to the upper surface, thereby avoiding the formation of pores at the bottom of the film, improving the contact between the perovskite layer and the substrate, and enhancing the efficiency and stability of perovskite devices.

[0033] This invention provides a method for preparing a perovskite layer using an anti-solvent method, comprising the following steps:

[0034] Provides substrate and perovskite precursor solution;

[0035] An anti-solvent is coated onto the substrate surface to form a liquid film;

[0036] The perovskite precursor solution is coated onto the liquid film and then annealed to form a perovskite layer.

[0037] In some embodiments, the solvent of the perovskite precursor solution includes any one or a combination of two or more of N,N-dimethylformamide, dimethyl sulfoxide, etc.

[0038] In some embodiments, the antisolvent includes any one or a combination of two or more of chlorobenzene, ethyl acetate, and diethyl ether.

[0039] In some embodiments, the thickness of the liquid film is 1-2 μm.

[0040] In some embodiments, the method specifically includes: after forming a liquid film by spin coating, continuing to add the spin-coated perovskite precursor solution.

[0041] In some embodiments, the perovskite precursor includes any one or more combinations of MAPbI3, FAPbI3, FAx1CsylPbI3, FAx2MAy2CszPbI3, and FAx3Csy3PbImBm, wherein x1+y1=1, x2+y2+z=1, x3+y3=1, and m+n=1.

[0042] In some embodiments, the spin coating speed is 1500-3500 rpm.

[0043] In some embodiments, the dropping rate of the perovskite precursor solution is 150-250 μL / s.

[0044] In some embodiments, the concentration of the perovskite precursor solution is 1-1.4 mol / L.

[0045] In some embodiments, the annealing treatment is performed at a temperature of 100-150°C for 30-40 minutes.

[0046] As some typical application examples, the methods in the above technical solutions can be implemented through the following specific steps:

[0047] Step 1: Prepare a 1.4M perovskite solution. The solvent can be N,N-dimethylformamide:dimethyl sulfoxide = 4:1.

[0048] Step 2: Spin-coat approximately 400 microliters of antisolvent onto the substrate surface. Antisolvents such as chlorobenzene, ethyl acetate, and diethyl ether can be used.

[0049] Step 3: During spin coating, add perovskite precursor solution dropwise.

[0050] Step 4: Place the perovskite film on a heating plate for annealing at a temperature of about 120°C for about 30 minutes.

[0051] This invention also provides a perovskite optoelectronic device, comprising a hole transport layer, a perovskite layer, and an electron transport layer stacked sequentially, wherein the perovskite layer is fabricated by the method provided in any of the above embodiments.

[0052] In some embodiments, the perovskite optoelectronic device further includes a first electrode and a second electrode, wherein the first electrode is electrically connected to the hole transport layer and the second electrode is electrically connected to the electron transport layer.

[0053] In some implementations, the hole transport layer is made of any one of Spiro-OMeTAD, PEDOT:PSS, P3HT, PTAA, and PCDTBT.

[0054] In some implementations, the thickness of the hole transport layer is 20-500 nm.

[0055] In some embodiments, the thickness of the perovskite layer is 300-1000 nm.

[0056] In some embodiments, the electron transport layer sequentially comprises a TiO2 layer with a thickness of 10-50 nm, a SnO2 layer with a thickness of 10-50 nm, and a buffer layer with a thickness of 10-20 nm. The buffer layer may be made of a fullerene derivative, but is not limited thereto; the electron transport layer may also employ a simple single-layer structure as used in the prior art.

[0057] As a typical application example of the above technical solution, in some applications, the perovskite optoelectronic device can be a forward-facing device or an inverted device.

[0058] Its specific structure can be: conductive substrate (as the first electrode) / first transport layer / perovskite layer / second transport layer / second electrode, wherein the material and thickness of each layer are as follows: the conductive substrate is one of FTO conductive glass, ITO conductive glass, FTO conductive plastic, and ITO conductive plastic, wherein the thickness of FTO is approximately 500 nm, and the thickness of ITO is approximately 300-400 nm; the three-segment electron transport layer serves as the first transport layer, consisting of: TiO2 with a thickness of approximately 10-50 nm, SnO2 with a thickness of approximately 10-50 nm, and a buffer layer with a thickness of 10-20 nm; the perovskite layer can be MAPbI3 (the structural formula of MA is CH3NH3). + The thickness of the first electrode can be 300–1000 nm; the second electrode, which is the hole transport layer, can be any one of Spiro-OMeTAD (2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirodifluorene), PEDOT:PSS, P3HT, PTAA, or PCDTBT, and its thickness can be 20–500 nm; the second electrode can be any one of Ag, Al, Au, or TCO, and its thickness can be approximately 100–300 nm.

[0059] The preparation methods for each layer of the perovskite solar cell are as follows: the conductive substrate is prepared by physical vapor deposition, evaporation or sputtering; the electron transport layer and hole transport layer are prepared by any one of spin coating, spraying or blade coating; the perovskite layer is prepared by the novel anti-solvent method provided in the above embodiments; and the metal second electrode is prepared by vacuum evaporation or vacuum sputtering.

[0060] Therefore, this invention provides a novel anti-solvent preparation process for perovskites, which can effectively avoid the formation of pores at the bottom during crystallization, enhance the contact force between the perovskite layer and the substrate, and improve the efficiency and stability of perovskite devices.

[0061] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0062] Comparative Example 1

[0063] This embodiment illustrates the fabrication process of a perovskite solar cell, including the fabrication process of the perovskite layer, as detailed below:

[0064] An FTO conductive glass is provided, wherein the FTO layer is 500 nm thick and serves as the first electrode. On the conductive glass, a TiO2 layer with a thickness of 25 nm, a SnO2 layer with a thickness of 30 nm, and a fullerene derivative layer with a thickness of 15 nm are sequentially prepared by spin coating as buffer layers. The above three layers constitute an electron transport layer. The conductive glass with the electron transport layer is used as a substrate to continue the following preparation process.

[0065] Prepare a 1.4M MAPbI3 perovskite solution with N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. Spin-coat the perovskite precursor solution onto the substrate surface at a spin speed of 4000 rpm. During the spin-coating process, add approximately 300 μL of chlorobenzene antisolvent at a suitable processing time (approximately 10 seconds before the end of the spin-coating process). Place the substrate loaded with the above liquid film on a hot plate for annealing at a temperature of approximately 120°C for approximately 30 minutes.

[0066] On the perovskite layer, spin coating and drying were carried out to prepare a 500 nm thick P3HT hole transport layer.

[0067] Then, a 200nm thick silver layer is vacuum-deposited on the hole transport layer as the second electrode.

[0068] The cross-sectional morphologies of the perovskite layer and electron transport layer prepared in this comparative example are as follows: Figure 2a As shown, a very obvious porous structure exists between the perovskite layer and the electron transport layer.

[0069] Example 1

[0070] This embodiment illustrates the fabrication process of a perovskite solar cell, including the fabrication process of the perovskite layer, as detailed below:

[0071] An FTO conductive glass is provided, wherein the FTO layer is 500 nm thick and serves as the first electrode. On the conductive glass, a TiO2 layer with a thickness of 25 nm, a SnO2 layer with a thickness of 30 nm, and a fullerene derivative layer with a thickness of 15 nm are sequentially prepared by spin coating. The above three layers constitute an electron transport layer. The conductive glass with the electron transport layer is used as a substrate to continue the following preparation process.

[0072] A 1.4M MAPbI3 perovskite precursor solution was prepared, with N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. Approximately 400 μL of chlorobenzene antisolvent was spin-coated onto the substrate surface at a spin speed of 1500 rpm, resulting in a liquid film thickness of 1 μm. During the spin-coating process, the perovskite precursor solution was added dropwise at a rate of 200 μL / s within the last 10 seconds before the spin-coating was completed. The substrate loaded with the liquid film was then placed on a hot plate for annealing at approximately 120°C for approximately 30 minutes, thereby forming a perovskite layer on the electron transport layer.

[0073] On the perovskite layer, spin coating and drying were carried out to prepare a 500 nm thick P3HT hole transport layer.

[0074] Then, a 200nm thick silver layer is vacuum-deposited on the hole transport layer as the second electrode.

[0075] The cross-sectional morphologies of the perovskite layer and electron transport layer prepared in this embodiment are as follows: Figure 2b As shown, there are no pores between the perovskite layer and the electron transport layer, resulting in good contact performance and preventing the intrusion of aging media such as moisture, which can improve the service life of the aforementioned devices.

[0076] Meanwhile, the current-voltage characteristic curves of the perovskite devices provided in this embodiment and Comparative Example 1 are tested as follows: Figure 3 As shown in Table 1, the photoelectric performance tests of the perovskite solar cells obtained in Example 1 and Comparative Example 1 are shown below.

[0077] Table 1. Photovoltaic performance test results of the solar cells provided in Example 1 and Comparative Example 1.

[0078]

[0079] from Figure 3 As can be clearly seen in Table 1, the short-circuit current and open-circuit voltage of the perovskite device provided in this embodiment are significantly improved compared with Comparative Example 1, and the fill factor and efficiency are also significantly improved.

[0080] Furthermore, the present invention also conducted aging tests on the perovskite devices provided in Example 1 and Comparative Example 1 under humid and hot conditions, and the relationship between their standardization efficiency and aging time is as follows: Figure 4 As shown in Table 2 below, it can be seen that Comparative Example 1, due to its porous structure, has significantly lower aging resistance than Example 1.

[0081] Table 2 Standardized efficiency of Example 1 and Comparative Example 1 after 30 days of aging.

[0082] Example 1 85.8％ Comparative Example 1 69.0％

[0083] Example 2

[0084] This embodiment illustrates a fabrication process for a perovskite solar cell, which is largely the same as that in Embodiment 1, with the only difference being:

[0085] In the preparation of the perovskite layer, 1.0 M FA was prepared. 0.6 Cs 0.4 PbI 0.8 Br 0.2 A perovskite precursor solution with N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 1:1 was spin-coated onto the substrate surface using approximately 400 μL of ethyl acetate as the anti-solvent at a spin-coating speed of 3500 rpm, resulting in a liquid film thickness of 2 μm. During the spin-coating process, the perovskite precursor solution was added dropwise at a rate of 150 μL / s within the last 10 seconds before the spin-coating was completed. The substrate loaded with the liquid film was then placed on a hot plate for annealing at 100°C for approximately 40 minutes, thereby forming a perovskite layer on the electron transport layer.

[0086] The perovskite device fabricated in this embodiment has an interface between the perovskite layer and the electron transport layer that is similar to that in Example 1, with no obvious pores.

[0087] Example 3

[0088] This embodiment illustrates a fabrication process for a perovskite solar cell, which is largely the same as that in Embodiment 1, with the only difference being:

[0089] In the preparation of the perovskite layer, a 1.2M FAPbI3 perovskite precursor solution was prepared, with N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 1:2. Approximately 400 μL of diethyl ether antisolvent was spin-coated onto the substrate surface at a spin speed of 3500 rpm, resulting in a liquid film thickness of 2 μm. During the spin-coating process, the perovskite precursor solution was added dropwise at a rate of 150 μL / s within 10 seconds before the end of the spin-coating. The substrate loaded with the liquid film was then placed on a hot plate for annealing at 150°C for approximately 30 minutes, thereby forming a perovskite layer on the electron transport layer.

[0090] The perovskite device fabricated in this embodiment has an interface between the perovskite layer and the electron transport layer that is similar to that in Example 1, with no obvious pores.

[0091] Example 4

[0092] This embodiment illustrates a fabrication process for a perovskite solar cell, which is largely the same as that in Embodiment 1, with the only difference being:

[0093] In the preparation of the perovskite layer, 1.2M FA was prepared. 0.5 Cs 0.5A PbI3 perovskite precursor solution was prepared using N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 1:2. Approximately 400 μL of diethyl ether was spin-coated onto the substrate surface at a spin speed of 2500 rpm, resulting in a liquid film thickness of 1.5 μm. During the spin-coating process, the perovskite precursor solution was added dropwise at a rate of 250 μL / s within the last 10 seconds before the spin-coating was completed. The substrate loaded with the liquid film was then placed on a hot plate for annealing at 150°C for approximately 30 minutes, thereby forming a perovskite layer on the electron transport layer.

[0094] The perovskite device fabricated in this embodiment has an interface between the perovskite layer and the electron transport layer that is similar to that in Example 1, with no obvious pores.

[0095] The cross-sectional morphology of the perovskite layers provided in Examples 2-4 was also tested. It was found that there were no obvious pore structures between the perovskite layers and the substrate in the above examples. At the same time, the current-voltage characteristic curves of the perovskite solar cells provided in Examples 2-4 were similar to those in Example 1, and they had the same level of electrical performance.

[0096] Based on the above embodiments and comparative examples, it is clear that the embodiments of the present invention propose a novel method for preparing perovskite layers using anti-solvent preparation. This method allows the crystallization of perovskite to begin from the lower surface and then gradually transition to the upper surface, thereby avoiding the formation of pores at the bottom of the perovskite layer, improving the contact between the perovskite film and the substrate, and thus improving the efficiency and stability of perovskite devices.

[0097] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite layer using an anti-solvent method, characterized in that, include: Provides substrates and perovskite precursor solutions; An anti-solvent is coated on the surface of the substrate to form a liquid film with a thickness of 1-2 μm; The perovskite precursor solution is coated onto the liquid film and then annealed to allow perovskite crystallization to begin from the lower surface and gradually transition to the upper surface to form a perovskite layer, thereby preventing the formation of pores at the bottom of the perovskite layer.

2. The method according to claim 1, characterized in that, The solvent of the perovskite precursor solution includes any one or a combination of two of N,N-dimethylformamide and dimethyl sulfoxide. And / or, the antisolvent includes any one or a combination of two or more of chlorobenzene, ethyl acetate, and diethyl ether.

3. The method according to claim 1, characterized in that, Specifically, it includes: After forming a liquid film using spin coating, the perovskite precursor solution is continuously added dropwise.

4. The method according to claim 3, characterized in that, The perovskite precursor includes MAPbI3, FAPbI3, and FA. x1 Cs y1 PbI3, FA x2 MA y2 Cs z PbI3 and FA x3 Cs y3 PbI m Br n Any one or more combinations of x1+y1=1, x2+y2+z=1, x3+y3=1, m+n=1.

5. The method according to claim 3, characterized in that, The spin coating speed is 1500-3500 rpm; And / or, the dropping rate of the perovskite precursor solution is 150-250 μL / s; And / or, the concentration of the perovskite precursor solution is 1-1.4 mol / L.

6. The method according to claim 1, characterized in that, The annealing process is performed at a temperature of 100-150℃ for 30-40 minutes.

7. A perovskite optoelectronic device, comprising a hole transport layer, a perovskite layer, and an electron transport layer stacked sequentially, characterized in that, The perovskite layer is prepared by the method described in any one of claims 1-6.

8. The perovskite optoelectronic device according to claim 7, characterized in that, It also includes a first electrode and a second electrode, wherein the first electrode is electrically connected to the hole transport layer and the second electrode is electrically connected to the electron transport layer.

9. The perovskite optoelectronic device according to claim 7, characterized in that, The material of the hole transport layer includes any one of Spiro-OMeTAD, PEDOT:PSS, P3HT, PTAA, and PCDTBT; And / or, the thickness of the hole transport layer is 20-500 nm; And / or, the thickness of the perovskite layer is 300-1000 nm; And / or, the electron transport layer includes a TiO2 layer with a thickness of 10-50 nm, a SnO2 layer with a thickness of 10-50 nm, and a buffer layer with a thickness of 10-20 nm, which are sequentially disposed.

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