Perovskite solar cell and preparation method and application thereof

Abstract

The invention provides a perovskite solar cell and a preparation method and application thereof, and the preparation method comprises the steps: preparing a perovskite thin film layer through a one-step solution method, and preparing an intermediate layer through a co-evaporation method, thereby enabling the thickness of the obtained intermediate layer to be controllable, enlarging the selection range of the material of the intermediate layer, and improving the production efficiency. The perovskite thin films with different components can be matched; the conductive substrate with the perovskite thin film layer and the intermediate layer is annealed in a solvent atmosphere, so that crystal growth of the intermediate layer is promoted, contact between the intermediate layer and the perovskite thin film layer is enhanced, and the intermediate layer and the perovskite thin film layer are promoted to form a whole; and finally, sequentially forming an electron transport layer and a back electrode on the surface of one side, far away from the conductive substrate, of the intermediate layer to obtain the perovskite solar cell. The preparation method is simple in process, fast in production rhythm and suitable for being amplified to a production line, and the photovoltaic performance and the stability of the prepared perovskite solar cell are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photovoltaic devices, and particularly relates to a perovskite solar cell and a preparation method and application thereof. BACKGROUND

[0002] In recent years, perovskite solar cells have become a research hotspot in the photovoltaic field due to their strong light absorption capacity, high carrier mobility, low preparation cost, and the advantage of being able to be prepared into flexible wearable devices.

[0003] The perovskite thin film is a key component for preparing the perovskite solar cell, and its preparation method is mainly divided into one-step method and two-step method. The one-step method mainly refers to one-step solution method, which specifically includes preparing a wet film by spin coating, blade coating, spraying or slot coating of a perovskite precursor solution, and then extracting the solvent by using a reverse solvent or VCD (VCD is the abbreviation of Vacuum Concentration Drying, which means vacuum concentration drying), and finally forming the perovskite thin film by annealing treatment. The two-step method includes a vacuum method, which includes using physical vapor deposition (PVD) or chemical vapor deposition (CVD) to directly prepare the perovskite precursor material on the substrate by co-evaporation or sequential evaporation in a vacuum state, and then promoting crystallization by annealing to form the perovskite thin film.

[0004] Among them, the one-step solution method for preparing the perovskite thin film has the advantages of low cost and easy preparation, but the crystalline quality of the prepared perovskite is poor, the grain size is small, and there are many defects, which hinders the improvement of device performance and stability; in addition, most of the anti-type perovskite components use C 60 As an electron transport layer, C 60 There are a large number of defects in the electron transport layer and at the interface between the electron transport layer and the perovskite absorption layer, which easily causes problems such as low device performance and instability. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a perovskite solar cell and a preparation method and application thereof, the preparation method uses one-step solution method and co-evaporation method for collocation, so that the thickness of the intermediate layer is controllable and the material selection range is wide, and at the same time has the advantages of simple process, fast production rhythm, suitable for scaling up to production line, etc., and the photovoltaic performance and stability of the prepared perovskite solar cell are significantly improved.

[0006] To achieve this purpose of the application, the following technical solutions are adopted:

[0007] In a first aspect, the present application provides a preparation method of a perovskite solar cell, which comprises the following steps:

[0008] (1) forming a hole transport layer on a conductive substrate;

[0009] (2) forming a perovskite film layer on a side surface of the hole transport layer away from the conductive substrate by using a one-step solution method;

[0010] (3) co-evaporating a source on a side surface of the perovskite film layer away from the conductive substrate to form an intermediate layer;

[0011] (4) annealing the conductive substrate with the intermediate layer formed thereon;

[0012] (5) sequentially forming an electron transport layer and a back electrode on a side surface of the intermediate layer away from the conductive substrate after the annealing to obtain the perovskite solar cell.

[0013] The preparation method of the perovskite solar cell provided by the application first forms a hole transport layer on a conductive substrate, and then forms a perovskite film layer on a side surface of the hole transport layer away from the conductive substrate by using a one-step solution method, so that the preparation of the perovskite film layer is very simple. Secondly, an intermediate layer is prepared on a side surface of the perovskite film layer away from the conductive substrate by using a co-evaporation method. The thickness of the intermediate layer prepared by using the co-evaporation method is good in controllability, and the components of the intermediate layer can be the same as or different from those of the perovskite film layer, thereby increasing the selectivity of the components of the intermediate layer, so that the perovskite film layer with different components can be matched. Moreover, the surface of the intermediate layer prepared by using the co-evaporation method is relatively rough, thereby enhancing the adhesion between the intermediate layer and the electron transport layer. Thirdly, the conductive substrate with the perovskite film layer and the intermediate layer formed thereon is annealed, so that the crystallization growth of the intermediate layer is promoted, the contact between the intermediate layer and the perovskite film layer is enhanced, and the perovskite film is formed as a whole. Finally, an electron transport layer and a back electrode are sequentially formed on a side surface of the intermediate layer away from the conductive substrate after the annealing, so that the perovskite solar cell is obtained. The preparation method is simple in process, fast in production rhythm, suitable for being enlarged to a production line, and the photovoltaic performance and stability of the perovskite solar cell prepared by using the preparation method are significantly improved.

[0014] Preferably, the chemical formula of a perovskite precursor for forming the perovskite film layer is Cs n FA 1-n PbX3, wherein 0≤n≤0.25, and X is at least one of Cl, Br or I.

[0015] Preferably, the material of the electron transport layer comprises C 60 .

[0016] Preferably, the electron transport layer comprises C 60 layer and BCP (BCP refers to bathocuproin) layer, and the C 60a layer is disposed between the intermediate layer and the BCP layer.

[0017] Preferably, the intermediate layer has a thickness of 5-80 nm, such as 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm or 80 nm, etc.

[0018] Preferably, the conductive substrate comprises FTO conductive glass, FTO representing fluorine-doped tin dioxide.

[0019] Preferably, the hole transport layer is deposited on the conductive substrate by magnetron sputtering.

[0020] Preferably, the material of the hole transport layer comprises nickel oxide.

[0021] Preferably, the back electrode comprises a copper electrode.

[0022] Preferably, the one-step solution method comprises: coating a perovskite precursor solution, solvent extraction, and then sequentially performing the steps of first annealing and second annealing.

[0023] Preferably, the coating method comprises any one or a combination of at least two of spin coating, blade coating, spray coating or slot coating.

[0024] Preferably, the solvent extraction method comprises anti-solvent extraction or VCD method.

[0025] Preferably, the temperature of the first annealing is 60-80°C, such as 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, etc.

[0026] Preferably, the time of the first annealing is 0.1-5 min, such as 0.1 min, 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min or 5 min, etc.

[0027] Preferably, the temperature of the second annealing is 120-160°C, such as 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 155°C or 160°C, etc.

[0028] Preferably, the time of the second annealing is 20-30 min, such as 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min or 30 min, etc.

[0029] Preferably, the co-evaporation is performed in a vacuum evaporation apparatus, and the evaporation source comprises CsX, PbX2, MAX and FAX, wherein X is selected from any one of Cl, Br or I.

[0030] Preferably, the material of the intermediate layer is a perovskite material.

[0031] Preferably, the evaporation rate of the evaporation source is independently For example 0.5 or and further preferably If the evaporation rate is too slow, it is easy to cause the preparation process to take a long time, and it is not easy to form a rough surface, which is not conducive to enhancing the adhesion between the intermediate layer and the C 60 layer. If the evaporation rate is too fast, it will cause the intermediate layer formed by co-evaporation to have poor combination with the perovskite thin film layer, and it is easy to cause the intermediate layer film to be too rough, which will also affect the combination between the intermediate layer and the C 60 layer, thereby increasing the series resistance and hindering the improvement of device performance; in addition, if the evaporation rate is too fast, it is also not conducive to the control of the thickness of the intermediate layer.

[0032] Preferably, the annealing treatment in step (4) is performed in a solvent atmosphere; the solvent comprises any one or a combination of at least two of DMF (DMF represents N,N-dimethylformamide), acetonitrile, DMSO (DMSO represents dimethyl sulfoxide), TMSO (TMSO represents tetramethylene sulfoxide) or NMP (NMP represents N-methyl pyrrolidone). Performing the annealing treatment in the above-mentioned specific solvent atmosphere can further promote the crystalline growth of the intermediate layer, and further enhance the contact between the intermediate layer and the perovskite thin film layer.

[0033] Preferably, the temperature of the annealing treatment in step (4) is 120-160℃, such as 120℃, 125℃, 130℃, 140℃, 150℃ or 160℃, etc.

[0034] Preferably, the time of the annealing treatment in step (4) is 20-30min, such as 20min, 22min, 24min, 26min, 28min or 30min, etc.

[0035] In a second aspect, the present application provides a perovskite solar cell, which is prepared by the preparation method as described in the first aspect.

[0036] In a third aspect, the present application provides a solar photovoltaic device, which comprises the perovskite solar cell as described in the second aspect.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] The preparation method of the perovskite solar cell provided by the present application adopts a one-step solution method to prepare a perovskite thin film layer, and then a co-evaporation method is used to prepare an intermediate layer, so that the thickness of the obtained intermediate layer is controllable, and the selection range of the intermediate layer material is increased, so that it can match perovskite thin films of different components. Then, the conductive substrate formed with the perovskite thin film layer and the intermediate layer is subjected to annealing treatment in a solvent atmosphere, which not only promotes the crystallization growth of the intermediate layer, but also enhances the contact between the intermediate layer and the perovskite thin film layer, and promotes the perovskite thin film to form a whole. Finally, an electron transport layer and a back electrode are formed in sequence on the side surface of the intermediate layer away from the conductive substrate after annealing treatment, and the perovskite solar cell is obtained. The preparation method is simple in process, fast in production rhythm, suitable for scaling up to a production line, and the photovoltaic performance and stability of the prepared perovskite solar cell are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A cross-sectional structure schematic diagram of the perovskite solar cell provided by the present application is shown in the figure.

[0040] In the figure, 1 is a conductive substrate, 2 is a hole transport layer, 3 is a perovskite thin film layer, 4 is an intermediate layer, 5 is an electron transport layer, and 6 is a back electrode. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0042] Unless otherwise specified, the raw materials involved in the following specific embodiments are all conventional materials in the art, and can be purchased on the market.

[0043] Example 1

[0044] A preparation method of a perovskite solar cell, specifically comprising the following steps:

[0045] (1) FTO conductive glass is used as a conductive substrate, and a layer of nickel oxide film is prepared on the FTO conductive glass by a magnetron sputtering method, serving as a hole transport layer;

[0046] (2) A Cs 0.1 FA 0.9 PbI3 precursor solution is coated on the side surface of the nickel oxide film away from the FTO conductive glass by scraping, and the solvent is DMF, then the solvent is removed by VCD method, and then annealing treatment is performed at 70℃ for 2min, and then annealing treatment is performed at 150℃ for 20min, to form a perovskite thin film layer;

[0047] (3) The FTO conductive glass with the perovskite thin film layer formed is cooled and then transferred to a vacuum evaporation apparatus for co-evaporation. The evaporation source 1 is CsI, the evaporation source 2 is FAI, the evaporation source 3 is PbI2, and the evaporation source 4 is MACl. The vacuum is evaporated to 4×10⁻⁶. -4 Pa, each evaporation source is heated, and the evaporation rate is controlled by adjusting the temperature of each evaporation source. After co-evaporation, an intermediate layer with a thickness of 30 nm is formed;

[0048] (4) Transfer the FTO conductive glass with the intermediate layer to an annealing furnace and anneal it in a DMF atmosphere at 150°C for 20 min.

[0049] (5) Evaporate 25nm thick C coatings on the side of the annealed intermediate layer away from the FTO conductive glass. 60 The perovskite solar cell is obtained by evaporating an 80nm thick Cu electrode after adding a 5nm thick BCP layer.

[0050] The cross-sectional structure diagram of the final perovskite solar cell obtained in this embodiment is shown below. Figure 1 As shown, it includes a conductive substrate 1, a hole transport layer 2, a perovskite thin film layer 3, an intermediate layer 4, an electron transport layer 5, and a back electrode 6, which are stacked together.

[0051] Examples 2-5

[0052] A method for preparing a perovskite solar cell differs from Example 1 in that the thickness of the passivation layer formed after co-evaporation in step (3) is 20 nm (Example 2), 10 nm (Example 3), 50 nm (Example 4) and 80 nm (Example 5), respectively. Other steps, parameters and materials are the same as in Example 1.

[0053] Example 6

[0054] A method for preparing a perovskite solar cell, which differs from Example 1 in that the evaporation rate of the evaporation source in step (3) is always... The other steps, parameters, and substances are the same as in Example 1.

[0055] Example 7

[0056] A method for preparing a perovskite solar cell differs from Example 1 in that the annealing process in step (4) is not carried out in a DMF atmosphere, while the other steps, parameters and materials are the same as in Example 1.

[0057] Comparative Example 1

[0058] A preparation method of a perovskite solar cell, which is different from example 1 in that steps (3) and (4) are not performed, and a 25 nm thick C 60 layer and a 5 nm thick BCP layer are respectively evaporated on the surface of the FTO conductive glass on which the perovskite thin film layer is formed, and other steps, parameters and substances are the same as those in example 1.

[0059] Comparative example 2

[0060] A preparation method of a perovskite solar cell, which is different from example 1 in that step (4) is not performed, and a 25 nm thick C 60 layer and a 5 nm thick BCP layer are respectively evaporated on the surface of the passivation layer of the FTO conductive glass, and other steps, parameters and substances are the same as those in example 1.

[0061] Performance test:

[0062] The perovskite solar cells prepared in examples 1-7 and comparative examples 1-2 are subjected to photovoltaic performance test and stability test;

[0063] The photovoltaic performance test conditions are that the effective area of the cell is 1 cm 2 , the JV curve is tested under AM1.5 simulated sunlight, and the irradiance provided by the solar simulator is 100 mW cm -2 ;

[0064] The stability test conditions are that the cell is placed in a nitrogen glove box for 500 h without packaging;

[0065] The test results of the above photovoltaic performance test and stability test are shown in table 1;

[0066] Table 1

[0067]

[0068] According to the data in table 1, it can be seen that:

[0069] (1) In the photovoltaic performance test of the perovskite solar cells provided in examples 1-7, Isc can reach 24.53 mA, Voc can reach 1.05 V, and PCE can reach 19.62%, which has excellent photovoltaic performance;

[0070] and the stability test shows that the efficiency decay rate after 500 h is as low as 2.39%, which has excellent stability.

[0071] (2) Compared with Example 1, the perovskite solar cell provided in Comparative Example 1 has lower Isc, Voc, PCE and fill factor in photovoltaic performance test due to the absence of an intermediate layer and the lack of annealing treatment. The photovoltaic performance is poor, and the stability test shows that the efficiency degradation rate is as high as 9.01% after 500 hours, indicating poor device stability.

[0072] (3) Compared with Example 1, the perovskite solar cell provided in Comparative Example 2 did not undergo annealing after co-evaporation of the intermediate layer, resulting in an efficiency of only 17.23% for the forward scanning device. Furthermore, the stability test showed that the efficiency degradation rate was as high as 5.68% after 500 hours, indicating poor device stability.

[0073] (4) Further comparison of the data of Example 1 and Example 6 shows that the evaporation rate of the evaporation source in step (3) co-evaporation process should not be too high, otherwise it will affect the improvement of device performance.

[0074] (5) Further comparison of the data from Example 1 and Example 7 shows that the annealing process in step (4) was not carried out in a solvent atmosphere, which also led to a decrease in device performance.

[0075] The applicant declares that this invention illustrates a perovskite solar cell, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above process steps, meaning that this invention does not necessarily rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A method for preparing a perovskite solar cell, characterized in that, The preparation method includes the following steps: (1) A hole transport layer is formed on a conductive substrate; (2) A perovskite thin film layer is formed on the side of the hole transport layer away from the conductive substrate using a one-step solution method; (3) Co-evaporate the evaporation source on the surface of the perovskite thin film layer away from the conductive substrate to form an intermediate layer; (4) Anneal the conductive substrate with the intermediate layer formed; (5) An electron transport layer and a back electrode are sequentially formed on the side of the intermediate layer away from the conductive substrate after annealing to obtain the perovskite solar cell.

2. The preparation method according to claim 1, characterized in that, The chemical formula of the perovskite precursor forming the perovskite thin film layer is Cs. n FA 1-n PbX3, where 0≤n≤0.25, and X is at least one of Cl, Br or I; Preferably, the material of the electron transport layer includes C. 60 ; Preferably, the electron transport layer includes C 60 Layer and BCP layer, and the C 60 The layer is positioned between the intermediate layer and the BCP layer.

3. The preparation method according to claim 1 or 2, characterized in that, The thickness of the intermediate layer is 5–80 nm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The one-step solution method includes: coating a perovskite precursor solution, solvent extraction, and then sequentially performing a first annealing and a second annealing step; Preferably, the temperature of the first annealing is 60-80°C, and the time is 0.1-5 min; Preferably, the temperature of the second annealing is 120-160°C, and the time is 20-30 minutes.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The evaporation source includes CsX, PbX2, MAX and FAX, wherein X is selected from at least one of Cl, Br or I; Preferably, the intermediate layer is made of perovskite.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The evaporation rates of the evaporation sources are each independent. Preferred 7. The preparation method according to any one of claims 1 to 6, characterized in that, The annealing process described in step (4) is performed under a solvent atmosphere; The solvent includes any one or a combination of at least two of DMF, acetonitrile, DMSO, TMSO, or NMP.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The annealing process in step (4) is carried out at a temperature of 120–160°C for 20–30 minutes.

9. A perovskite solar cell, characterized in that, The perovskite solar cell is prepared using the preparation method described in any one of claims 1 to 8.

10. A solar photovoltaic device, characterized in that, The solar photovoltaic device includes the perovskite solar cell as described in claim 9.

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