Inverted perovskite solar cells based on hydrophobic polymer electron and hole transport materials and methods of making the same

Abstract

The application discloses a reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials and a preparation method thereof. In the preparation method, the hole transport layer and the electron transport layer of the perovskite solar cell are prepared by a simple one-step spin coating method using a hydrophobic conjugated polymer solution, and are arranged on the two sides of the perovskite active layer, thereby playing a good protective role on the light absorption performance of the perovskite material, and significantly improving the service life of the prepared unsealed perovskite solar cell. In addition, since the two types of conjugated polymer raw materials used have excellent film forming performance, the matching degree with the intermediate perovskite active layer is high and the charge transport efficiency is balanced, so that the conductivity of the cell is good, the photoelectric conversion efficiency is high, and there is almost no hysteresis effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite solar cell preparation, and particularly relates to a reversed perovskite solar cell based on hydrophobic polymer electron and hole transport materials and a preparation method thereof. BACKGROUND

[0002] Metal halide perovskite has excellent photoelectric performance, especially in the field of solar cells. In just a few years, the photoelectric conversion efficiency of perovskite solar cells has reached 23.3% from the initial 3.8%, which is comparable to commercial crystalline silicon solar cells. Meanwhile, perovskite materials can be prepared by a solution method, and the film forming method is simple and the industrial cost is low, which is very suitable for large-area production.

[0003] However, the perovskite material itself is sensitive to humidity, and the crystal structure is easily destroyed due to the erosion of water vapor and oxygen in the air, so that the original light absorption ability is lost. Therefore, the unsealed perovskite solar cell is often difficult to maintain long-term stability. In the prior art, in order to solve this problem, a patent application with the application number 201811271676.9 coats a hydrophobic coating on the surface of the perovskite light absorption layer to improve the resistance of the perovskite material to the water vapor environment, thereby prolonging the service life of the battery. However, this method obviously increases the preparation process of the perovskite solar cell, and the thickness precision of the introduced coating is extremely high, which increases the processing difficulty of the battery. In addition, the preparation process of the hole transport material and the electron transport material used in the existing perovskite solar cell generally needs to be stacked in multiple layers, or needs to be doped, or needs to be post-processed, which further increases the complexity of the processing procedure, causes waste of raw materials, and greatly increases the cost and energy consumption. This series of challenges seriously hinders the commercialization process of perovskite solar cells.

[0004] Therefore, it is necessary to design an improved reversed perovskite solar cell based on hydrophobic polymer electron and hole transport materials to solve the above problems. SUMMARY

[0005] The present application aims to provide a preparation method of a reversed perovskite solar cell which has simple process, good conductivity, outstanding stability and almost no hysteresis effect.

[0006] To achieve the above-mentioned application purposes, the present application provides a preparation method of a reversed perovskite solar cell based on hydrophobic polymer electron and hole transport materials, which comprises the following steps:

[0007] S1. Pre-treating a transparent conductive glass substrate;

[0008] S2. Spinning a hydrophobic conjugated polymer solution on the transparent conductive glass substrate to prepare a hole transport layer;

[0009] S3. spin-coating a perovskite active layer on the surface of the hole transport layer;

[0010] S4. spin-coating a hydrophobic polymer electron transport material on the surface of the perovskite active layer to obtain an electron transport layer; the hydrophobic polymer electron transport material is F8BT;

[0011] S5. evaporating a metal electrode on the electron transport layer to obtain a reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials.

[0012] As a further improvement of the present application, in step S2, the hydrophobic conjugated polymer is one or more of poly(ethylenecarbazole), poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl], poly(3-hexylthiophene), and poly[bis(4-phenyl)(4-butylphenyl)amine].

[0013] As a further improvement of the present application, in step S5, the metal electrode is Ag, Au, or Al.

[0014] As a further improvement of the present application, in step S3, the perovskite active layer is prepared by a two-step spin-coating method.

[0015] As a further improvement of the present application, the two-step spin-coating method comprises the following steps:

[0016] S31. dissolving a mixture of MAI or / and FAI and PbI2 in a mixed solvent of DMF and DMSO to obtain a precursor solution, and spin-coating the precursor solution on the surface of the hole transport layer preheated at 50-80°C;

[0017] S32. rapidly spin-coating a MAI / IPA solution on the film obtained in S31 and heat treating at 80-120°C for 10-60 min.

[0018] To achieve the above-mentioned objectives, the present invention also provides an inverted perovskite solar cell based on a hydrophobic polymer electron and hole transport material. The inverted perovskite solar cell comprises, from bottom to top, a transparent conductive glass substrate (1), a hole transport layer (2), a perovskite active layer (3), an electron transport layer (4), and a metal electrode (5). The hole transport layer is prepared from a hydrophobic conjugated polymer solution of one or more of the following: polyvinylcarbazole, poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl], poly3-hexylthiophene, and poly[bis(4-phenyl)(4-butylphenyl)amine].

[0019] As a further improvement of the present invention, the electron transport layer is prepared from F8BT as raw material.

[0020] As a further improvement of the present invention, the thickness of the hole transport layer is 5 to 50 nm.

[0021] As a further improvement of the present invention, the thickness of the electron transport layer is 5 to 30 nm.

[0022] As a further improvement of the present invention, the transparent conductive glass substrate includes, but is not limited to, ITO and FTO.

[0023] The beneficial effects of this invention are:

[0024] 1. The reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials of the present invention introduces a hole transport layer and an electron transport layer with outstanding hydrophobicity and good film-forming properties directly on both sides of the perovskite active layer. This enables the perovskite active layer, which is originally sensitive to humidity, to have self-encapsulation characteristics, which can fully resist the erosion and damage of perovskite material by moisture in the air. This ensures that the prepared solar cell can maintain good stability in the atmosphere even without encapsulation.

[0025] 2. The reverse perovskite solar cell of the present invention, based on hydrophobic polymer electron and hole transport materials, selects two types of raw materials with balanced charge transport efficiency as electron transport materials and hole transport materials respectively, and the two-end transport layers and the middle perovskite active layer are highly matched, resulting in good conductivity, high photoelectric conversion efficiency and almost no hysteresis effect of the cell.

[0026] 3. The electron transport layer and hole transport layer in the reverse perovskite solar cell of the present invention are both prepared by one-step spin coating using a solution method. The preparation process does not require doping or post-processing, and the process is simple, low-cost, highly reproducible, and has great industrialization advantages. Attached Figure Description

[0027] Figure 1 Molecular formula of F8BT in the present application.

[0028] Figure 2 Water contact angle test diagram of the electron transport layer in Example 1 of the present application.

[0029] Figure 3 Perovskite film morphology diagram of the present application.

[0030] Figure 4 Structure diagram of the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material of the present application.

[0031] Figure 5 Photovoltaic conversion efficiency diagram of the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material prepared in Example 1 of the present application.

[0032] Figure 6 Photovoltaic conversion efficiency diagram of the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material prepared in Example 1 of the present application before and after being placed in the atmosphere for 30 days. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be described in detail below with reference to the drawings and specific embodiments.

[0034] Here, it also needs to be noted that, in order to avoid the present application being obscured by unnecessary details, only the structures and / or processing steps closely related to the scheme of the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0035] In addition, it also needs to be noted that the term “comprising”, “containing” or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0036] The present application provides a preparation method of an inverted perovskite solar cell based on a hydrophobic polymer electron and hole transport material, comprising the following steps:

[0037] S1. Pre-treating a transparent conductive glass substrate;

[0038] S2. Spin-coating a hydrophobic conjugated polymer solution on the transparent conductive glass substrate to prepare a hole transport layer;

[0039] S3. spin-coating a perovskite active layer on the surface of the hole transport layer;

[0040] S4. spin-coating a hydrophobic polymer electron transport material on the surface of the perovskite active layer to obtain an electron transport layer; wherein the hydrophobic polymer electron transport material is one or more of F8BT and its related derivatives;

[0041] S5. evaporating a metal electrode on the electron transport layer to obtain a reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials.

[0042] In step S2, the hydrophobic conjugated polymer is one or more of poly(2-vinylcarbazole) (PVK), poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT), poly(3-hexylthiophene) (P3HT), poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD).

[0043] In step S2, the thickness of the hole transport layer obtained is 5-50 nm.

[0044] In step S4, the thickness of the electron transport layer obtained is 5-30 nm.

[0045] In step S5, the metal electrode is Ag, Au or Al.

[0046] In step S3, the perovskite active layer is prepared by a two-step spin-coating method.

[0047] The two-step spin-coating method comprises the following steps:

[0048] S31. dissolving a mixture of MAI or / and FAI and PbI2 in a mixed solvent of DMF and DMSO to obtain a precursor solution, and spin-coating the precursor solution on the surface of the hole transport layer preheated at 50-80°C;

[0049] S32. rapidly spin-coating a MAI / IPA solution on the film obtained in S31 and heat-treating at 80-120°C for 10-60 min.

[0050] In step S1, the transparent conductive glass substrate includes but is not limited to ITO, FTO.

[0051] The reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials obtained comprises a transparent conductive glass substrate layer 1, a hole transport layer 2, a perovskite active layer 3, an electron transport layer 4, and a metal electrode 5, which are stacked layer by layer, and the structure is as shown in Figure 4 .

[0052] The preparation method of the reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials of the present invention will be described below with reference to Comparative Examples 1-3 and Examples 1-3:

[0053] Comparative Example 1

[0054] A conventional method for fabricating an inverted perovskite solar cell includes the following steps:

[0055] S1. The transparent conductive substrate ITO was ultrasonically cleaned in deionized water and ethanol for 10 min and dried, and then treated with ultraviolet-ozone for 10 min to remove residual organic matter.

[0056] S2. A hydrophilic PEDOT:PSS film was deposited on the surface of the above ITO substrate by spin coating, and then heat-treated at 130°C for 15 min to obtain a hole transport material layer PEDOT:PSS film.

[0057] S3. A mixed solution of 650 mg / mL MAI and PbI2 (mass ratio 1:12) was spin-coated onto the surface of a PEDOT:PSS film. Then, a 25 mg / mL MAI solution was rapidly spin-coated onto the surface. The resulting film was then heat-treated on a hot plate at 100°C for 15 min to obtain the perovskite active layer MAPbI3 film, with the surface morphology as shown. Figure 3 As shown;

[0058] S4. PC is deposited on the surface of the above MAPbI3 thin film using spin coating. 61 The BM film has a thickness of approximately 20 nm and a water contact angle of 51°.

[0059] S5. In ITO / PEDOT:PSS / MAPbI3 / PC 61 The battery was fabricated by vapor-depositing an 80nm thick Ag metal electrode on the BM surface.

[0060] Comparative Example 2

[0061] This comparative example demonstrates the fabrication of an inverted perovskite solar cell based on a hydrophobic polymer hole transport material. The only difference between this comparative example and Comparative Example 1 is that in step S2, the pretreatment of the ITO substrate only requires ultrasonic cleaning, without UV-ozone treatment. Furthermore, the hydrophobic PCDTBT thin film is spin-coated onto the ITO substrate surface, and a uniform hole transport material layer of approximately 10 nm thickness can be obtained without heat treatment. Other steps are essentially the same as in Comparative Example 1 and will not be repeated here.

[0062] Comparative Example 3

[0063] This comparative example demonstrates the fabrication of an inverted perovskite solar cell based on a hydrophobic polymer electron transport material. The difference between this comparative example and Comparative Example 1 is that, in step S4 above, a hydrophobic F8BT film (water contact angle of 98°) is spin-coated onto the surface of the MAPbI3 film. The molecular formula of F8BT is as follows: Figure 1 As shown, the water contact angle is as follows Figure 2 As shown, the film thickness is about 20 nm, which serves as the electron transport material layer of the battery. The other steps are basically the same as those in Comparative Example 1, and will not be repeated here.

[0064] Examples 1-3

[0065] Examples 1-3 prepared three types of inverted perovskite solar cells based on hydrophobic polymer electron and hole transport materials. The only difference between Examples 1-3 and Comparative Example 2 is that in step S2, a hydrophobic film was spin-coated onto the surface of the ITO substrate without UV-ozone pretreatment, and the type and thickness of the hydrophobic film used were different. Furthermore, the hole transport material layer could be obtained without heat treatment. The other steps were basically the same as in Comparative Example 2 and will not be repeated here. The type and thickness of the hydrophobic film used for the hole transport material layer in Examples 1-3, as well as the average size of the perovskite grains, are shown in the table below:

[0066] Solar cell type Kind and thickness of hydrophobic film Perovskite grain average size Comparative Example 1 PEDOT:PSS film; 30 nm about 240 nm Example 1 PVK film; 10 nm about 420 nm Example 2 P3HT film; about 6 nm about 440 nm Example 3 poly-TPD film; about 15 nm about 450 nm

[0067] The roughness and hydrophobicity properties of the hole transport layers prepared in Comparative Examples 1-3 and Examples 1-3 were tested, and the results are shown in Table 1:

[0068] Table 1. Test results of roughness and hydrophobicity of each hole transport layer.

[0069]

[0070] The photovoltaic performance of the reverse-mounted solar cells prepared in Comparative Examples 1-3 and Examples 1-3 was tested, and the results are shown in Table 2:

[0071] Table 2 Performance test results of Comparative Examples 1-3 and Examples 1-3

[0072]

[0073] Please see Figure 5As shown in Table 2, and it can be seen from the data in Table 2 that, compared with the conventional inverted perovskite solar cell in Comparative Example 1, the photovoltaic conversion efficiency of the inverted perovskite solar cell based on the hydrophobic polymer electron transport material in Comparative Example 2 and the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material in Comparative Example 3 is obviously improved, which is due to the good film-forming performance and uniformity of the polymer solution used for preparing the electron transport layer and the hole transport layer, which can be known from the data of the average roughness in Table 1; the high uniformity is conducive to the good interface contact between the hole transport layer and the perovskite active layer, and the conjugated structure ensures the good conductivity, thereby obviously promoting the photovoltaic conversion efficiency of the solar cell; at the same time, the hydrophobic hole transport layer is conducive to inducing the crystallization and growth of the crystals in the upper perovskite active layer, so that larger perovskite grains are obtained, and the prepared device can obtain higher short-circuit current; at the same time, the obvious improvement of the open-circuit voltage also indicates that the matching degree of the band gap of the perovskite active layer and the two end transport layers in the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material is higher; in addition, the hysteresis effect of the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material prepared in Examples 1-3 is obviously improved, and similar results cannot be seen in Comparative Examples 2 and 3, which is related to the good balance of the charge transport efficiency of the selected electron transport material and hole transport material.

[0074] In addition, the perovskite solar cells prepared in Comparative Examples 1-3 and Examples 1-3 were subjected to stability test, and the photovoltaic conversion efficiency of each type of unsealed perovskite solar cell after being stored in the atmospheric environment for 30 days is shown in Table 3.

[0075] Table 3: Test results of photovoltaic conversion efficiency after 30 days of Comparative Examples 1-3 and Examples 1-3

[0076]

[0077] See Table 3 Figure 6 As shown in Table 2, and it can be seen from the data in Table 2 that, compared with the conventional inverted perovskite solar cell in Comparative Example 1, the photovoltaic conversion efficiency of the inverted perovskite solar cell based on the hydrophobic polymer electron transport material in Comparative Example 2 and the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material in Comparative Example 3 is obviously improved, which is due to the good film-forming performance and uniformity of the polymer solution used for preparing the electron transport layer and the hole transport layer, which can be known from the data of the average roughness in Table 1; the high uniformity is conducive to the good interface contact between the hole transport layer and the perovskite active layer, and the conjugated structure ensures the good conductivity, thereby obviously promoting the photovoltaic conversion efficiency of the solar cell; at the same time, the hydrophobic hole transport layer is conducive to inducing the crystallization and growth of the crystals in the upper perovskite active layer, so that larger perovskite grains are obtained, and the prepared device can obtain higher short-circuit current; at the same time, the obvious improvement of the open-circuit voltage also indicates that the matching degree of the band gap of the perovskite active layer and the two end transport layers in the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material is higher; in addition, the hysteresis effect of the inverted perovskite solar cell based on the hydrophobic polymer electron and hole transport material prepared in Examples 1-3 is obviously improved, and similar results cannot be seen in Comparative Examples 2 and 3, which is related to the good balance of the charge transport efficiency of the selected electron transport material and hole transport material.

[0078] In summary, the present application provides a reversed perovskite solar cell based on hydrophobic polymer electron and hole transport materials and a preparation method thereof. The hydrophobic electron transport layer and hole transport layer prepared by a simple one-step spin-coating solution method not only have good conductivity and good matching degree with the intermediate perovskite active layer, but also can significantly improve the stability of the unsealed perovskite solar cell in the atmosphere. At the same time, since two types of raw materials with balanced charge transport efficiency are selected as the electron transport material and the hole transport material of the battery, the battery has almost no hysteresis effect.

[0079] The above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing an inverted perovskite solar cell based on hydrophobic polymer electron and hole transport materials, characterized in that, comprising the following steps: S1. Pre-treating a transparent conductive glass substrate; S2. Spin-coating a hydrophobic conjugated polymer solution on the transparent conductive glass substrate to obtain a hole transport layer; the hydrophobic conjugated polymer is one or more of poly(ethylenecarbazole), poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl], poly(3-hexylthiophene), poly[bis(4-phenyl)(4-butylphenyl)amine]; S3. Spin-coating and depositing a perovskite active layer on the surface of the hole transport layer; the perovskite active layer is prepared by a two-step spin-coating method; the two-step spin-coating method comprises the following steps: S31. Dissolving a mixture of MAI or / and FAI and PbI2 in a mixed solvent of DMF and DMSO to obtain a precursor solution, and spin-coating the precursor solution on the surface of the hole transport layer preheated at 50-80°C; S32. Rapidly spin-coating a MAI / IPA solution on the film obtained in S31 and heat-treating at 80-120°C for 10-60 min; S4. Spin-coating and depositing a hydrophobic polymer electron transport material on the surface of the perovskite active layer to obtain an electron transport layer; the hydrophobic polymer electron transport material is F8BT; S5. Evaporating a metal electrode on the electron transport layer to obtain a reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials.

2. The method for preparing a reverse perovskite solar cell based on a hydrophobic polymer electron and hole transport material according to claim 1, characterized in that: In step S5, the metal electrode is Ag, Au or Al.

3. An inverted perovskite solar cell based on hydrophobic polymer electron and hole transport materials, characterized in that: The reverse perovskite solar cell based on hydrophobic polymer electron and hole transport materials is prepared by the preparation method of any one of claims 1-2, and comprises, from bottom to top, a transparent conductive glass substrate layer (1), a hole transport layer (2), a perovskite active layer (3), an electron transport layer (4), and a metal electrode (5); the hole transport layer is prepared from a hydrophobic conjugated polymer solution which is one or more of poly(ethylenecarbazole), poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl], poly(3-hexylthiophene), poly[bis(4-phenyl)(4-butylphenyl)amine].

4. The inverted perovskite solar cell based on hydrophobic polymer electron and hole transport materials according to claim 3, characterized in that: The electron transport layer is prepared from F8BT.

5. The inverted perovskite solar cell based on hydrophobic polymer electron and hole transport materials according to claim 3, characterized in that: The thickness of the hole transport layer is 5-50 nm.

6. The inverted perovskite solar cell based on hydrophobic polymer electron and hole transport materials according to claim 3, characterized in that: The thickness of the electron transport layer is 5-30 nm.

7. The inverted perovskite solar cell based on hydrophobic polymer electron and hole transport materials according to claim 3, characterized in that: The transparent conductive glass substrate is ITO or FTO.

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