Organic solar cell with large-area uniform active layer and preparation method thereof

Abstract

The invention relates to the technical field of organic solar cells, in particular to an organic solar cell with a large-area uniform active layer and a preparation method of the organic solar cell. The organic solar cell comprises a transparent conductive substrate, a hole transport layer, a quasi-plane heterojunction active layer, an electron transport layer and a metal electrode from bottom to top, the quasi-plane heterojunction active layer comprises a polymer donor film and a small molecule receptor film; the polymer donor thin film is deposited on the hole transport layer through a blade coating process, and the small molecule receptor thin film is deposited on the polymer donor thin film through the blade coating process under an external magnetic field. The preparation method can be compatible with an existing printing technology, the donor and the acceptor are induced to form a good phase separation scale through a magnetic field auxiliary means, the permeation process of the acceptor solution to the donor film in the deposition process is optimized, the more uniform active layer film with few defect modes is formed, dissociation and transmission of holes and electrons are facilitated, and the performance of the active layer film is improved. And the photoelectric conversion efficiency of the organic solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of organic solar cells, and particularly relates to an organic solar cell with a large-area uniform active layer and a preparation method thereof. Background Art

[0002] Organic solar cells (OSCs) have great application potential in scenarios such as building integrated photovoltaics, wearable electronic devices, and flexible lightweight photovoltaics due to their unique properties such as wet printing, light weight, and good flexibility.

[0003] In recent years, thanks to the emergence of non-fullerene electron acceptor and derivative materials, the power conversion efficiency of OSCs has been rapidly improved, and the limit PCE of single-junction cells has now exceeded 20%. Research shows that the morphology of the active layer will significantly affect the photovoltaic characteristics of organic solar cells and modules. The development of new materials is an effective means of regulating the morphology of the active layer. Through reasonable design of donor / acceptor materials, the density of bulk and surface defect states in the thin film can be reduced, which is beneficial to reducing non-radiative recombination under the working conditions of the battery, improving the transport of photo-generated carriers, and thus increasing the power conversion efficiency. In addition, introducing a third component to regulate the crystallization quality of donor / acceptor materials, optimizing the thin film deposition process to achieve a vertical phase distribution of donor / acceptor components, using post-treatment auxiliary techniques to reconstruct the microstructure of donor / acceptor materials, and interface engineering to improve the carrier transport characteristics in the active layer are all effective means to improve the photovoltaic performance of OSCs through active layer morphology regulation.

[0004] Existing contact coating and printing (blade coating, inkjet printing, slot die coating, etc.) technologies have shown good modification capabilities during the preparation of small-area devices in the laboratory. However, in the large-area module manufacturing process, due to the increase in the effective area, it is difficult to precisely control the morphology uniformity of the active layer, resulting in significant efficiency losses. In addition, with the development of emerging photovoltaic materials, existing contact coating and printing processes are difficult to be compatible with new materials, greatly increasing the manufacturing cost.

[0005] Based on this, developing a preparation method for organic solar cells that is compatible with existing printing processes, has good large-area active layer morphology uniformity, and high photoelectric conversion efficiency has important research and application value. Summary of the Invention

[0006] The present application provides an organic solar cell with a large-area uniform active layer and a preparation method thereof, aiming to solve the technical problems existing in existing organic solar cells, such as poor morphology uniformity of the active layer and low photoelectric conversion efficiency when the effective area increases, and difficulty in being compatible with existing printing processes.

[0007] To achieve the above object, the present application adopts the following technical solutions.

[0008] In the first aspect of the present application, an organic solar cell with a large-area uniform active layer is provided, which includes a transparent conductive substrate, a hole transport layer, a quasi-planar heterojunction active layer, an electron transport layer, and a metal electrode from bottom to top;

[0009] The quasi-planar heterojunction active layer includes a polymer donor thin film and a small molecule acceptor thin film; the polymer donor thin film is deposited on the hole transport layer by a blade coating process, and the small molecule acceptor thin film is deposited on the polymer donor thin film by a blade coating process under an external magnetic field.

[0010] Preferably, the polymer donor includes any one of PM6, D18, or D18-Cl; the thickness of the polymer donor thin film is 60-90 nm;

[0011] The small molecule acceptor includes any one of L8-BO, BTP-eC9, or Y6.

[0012] Preferably, the hole transport layer is a composite thin film of PEDOT:PSS and 2PACZ, and its thickness is 15-30 nm;

[0013] The electron transport layer is any one of PNDIT-F3N, PDINN, or PFN-Br thin films, and its thickness is 15-25 nm;

[0014] The metal electrode is Ag or Al, and its thickness is 85-100 nm.

[0015] In the second aspect of the present application, a method for preparing the above organic solar cell is provided, including:

[0016] S1, prepare a transparent conductive substrate;

[0017] S2, prepare a hole transport layer on the transparent conductive substrate by a blade coating process;

[0018] S3, prepare a polymer donor thin film on the surface of the hole transport layer by a blade coating process;

[0019] S4, in a magnetic field, coat an acceptor thin film on the surface of the polymer donor thin film by a blade coating process to form a quasi-planar heterojunction active layer;

[0020] S5, prepare an electron transport layer on the surface of the quasi-planar heterojunction active layer by a blade coating process;

[0021] S6, adopt a vacuum evaporation process to evaporate a metal electrode on the surface of the electron transport layer to obtain an organic solar cell.

[0022] Preferably, in step S3, the polymer donor is dissolved in toluene to prepare a donor solution with a concentration of 6-8 mg / mL;

[0023] The donor solution is spin-coated on the surface of the hole transport layer film at a speed of 40 - 60 mm / s at 80 - 100 °C, and the distance between the doctor blade and the hole transport layer film is 100 - 150 μm;

[0024] After spin-coating, anneal at 80 - 100 °C for 5 - 10 min to obtain a polymer donor film.

[0025] Preferably, in S4, the direction of the magnetic field is parallel or perpendicular to the polymer donor film, and the magnetic field strength is 0.25 - 0.75 T.

[0026] More preferably, in step S4, the small molecule acceptor is dissolved in toluene, and an additive is added to prepare an acceptor solution with a concentration of 9 - 12 mg / mL, where the dosage of the additive is 80 wt% of the dosage of the small molecule acceptor;

[0027] The acceptor solution is spin-coated on the surface of the polymer donor film at a speed of 60 - 70 mm / s at 80 - 100 °C, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm;

[0028] After spin-coating, anneal at 80 - 100 °C for 5 - 10 min to obtain a quasi-planar heterojunction active layer.

[0029] More preferably, the additive is diiodobenzene.

[0030] Preferably, in step S2, 2PACZ is dissolved in methanol to prepare a solution with a concentration of 1 - 5 mg / mL;

[0031] At 40 - 65 °C, first spin-coat PEDOT:PSS on the surface of the transparent conductive substrate at a speed of 10 - 30 mm / s, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm; then spin-coat the solution on the transparent conductive substrate coated with PEDOT:PSS at a speed of 10 - 30 mm / s, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm;

[0032] After spin-coating, anneal at 150 - 200 °C for 15 - 20 min to obtain a hole transport layer film.

[0033] Preferably, in step S5, PNDIT-F3N, PDINN or PFN-Br is dissolved in ethanol to prepare a solution with a concentration of 1 - 5 mg / mL;

[0034] The solution is spin-coated on the surface of the quasi-planar heterojunction active layer at a speed of 10 - 30 mm / s at 40 - 50 °C, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm; to obtain an electron transport layer film.

[0035] Compared with the prior art, the beneficial effects of the present application are as follows:

[0036] The preparation method of the present application adjusts the active layer thin film in the wet film state by applying an external magnetic field during the doctor blade coating process. Without other complex post-treatment operations, it can be compatible with existing printing technologies, has high repeatability, and is suitable for the preparation of large-area devices.

[0037] The present application induces a good phase separation scale between the donor and acceptor by means of magnetic field assistance, optimizes the penetration process of the acceptor solution into the donor thin film during the deposition process. Without adding extra components and avoiding cumbersome post-treatment, an active layer thin film with fewer defects and more uniformity can be formed, which is beneficial to the dissociation and transport of holes and electrons, and improves the photoelectric conversion efficiency of organic solar cells. The present application has important value for the preparation of high-performance organic solar cells. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is the current density-open circuit voltage curve graph of the organic solar cells of Examples 1-2 and Comparative Example 1;

[0040] Figure 2 It is the current density-open circuit voltage curve graph of the organic solar cells of Examples 3-4 and Comparative Example 2;

[0041] Figure 3 It is the current density-open circuit voltage curve graph of the organic solar cells of Examples 5-6 and Comparative Example 3;

[0042] Figure 4 It is the SEM graph of the active layer thin film of the organic solar cells of Example 2 and Comparative Example 1;

[0043] Figure 5 It is the external quantum efficiency (EQE) spectrum graph of the organic solar cells of Example 4 and Comparative Example 2. Detailed Embodiments

[0044] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0045] In the following description of this embodiment, terms such as "including", "comprising", "having", and "containing" are all open-ended terms, meaning including but not limited to.

[0046] In the following description of this embodiment, the term "and / or" is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and both A and B exist simultaneously. Among them, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0047] In the following description of this embodiment, the term "at least one" means one or more, and "multiple" means two or more. "At least one of the following items (pieces)" or its similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0048] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0049] Those skilled in the art should understand that in the following description of the embodiments of the present application, the sequence numbers do not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0050] Those skilled in the art should understand that the numerical ranges in the embodiments of the present application should be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0051] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the art to which this application pertains. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0052] In a first aspect, this application provides an organic solar cell with a large-area uniform active layer, which includes a transparent conductive substrate, a hole transport layer, a quasi-planar heterojunction active layer, an electron transport layer, and a metal electrode from bottom to top;

[0053] The quasi-planar heterojunction active layer includes a polymer donor thin film and a small molecule acceptor thin film; the polymer donor thin film is deposited on the hole transport layer by a blade coating process, and the small molecule acceptor thin film is deposited on the polymer donor thin film by a blade coating process under an external magnetic field.

[0054] In this application, the polymer donor is a wide-bandgap polymer donor, including any one of PM6, D18, or D18-Cl; the small molecule acceptor is a non-fullerene acceptor, including any one of L8-BO, BTP-eC9, or Y6. Among them, the chemical structural formulas of some polymer donors and small molecule acceptors are as follows:

[0055]

[0056] In this application, the thickness of the polymer donor thin film is preferably 60 - 90 nm; the hole transport layer is a composite thin film of PEDOT:PSS and 2PACZ, and its thickness is 15 - 30 nm; the electron transport layer is any one of PNDIT-F3N, PDINN, or PFN-Br thin films, and its thickness is 15 - 25 nm; the metal electrode is Ag or Al, and its thickness is 85 - 100 nm. The transparent conductive substrate can be selected from common transparent conductive materials in the art, such as ITO conductive glass.

[0057] In a second aspect, this application provides a method for preparing the above-mentioned organic solar cell, including:

[0058] S1, prepare a transparent conductive substrate;

[0059] The ITO conductive glass is ultrasonically cleaned with a cleaning agent, deionized water, and isopropyl alcohol for 30 minutes each in turn, dried with nitrogen, and placed in a UV light cleaning machine for surface treatment for 30 minutes to obtain a clean ITO glass substrate for standby.

[0060] S2. Prepare a hole transport layer on the transparent conductive substrate by the doctor blade coating process;

[0061] Specifically, dissolve 2PACZ in methanol to prepare a solution with a concentration of 1 - 5 mg / mL; at 40 - 65 °C, first doctor blade coat PEDOT:PSS on the surface of the transparent conductive substrate at a speed of 10 - 30 mm / s, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm; then doctor blade coat the above solution on the surface of the transparent conductive substrate coated with PEDOT:PSS at a speed of 10 - 30 mm / s, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm;

[0062] After doctor blade coating, anneal at 150 - 200 °C for 15 - 20 min to obtain a hole transport layer thin film.

[0063] S3. Prepare a polymer donor thin film on the surface of the hole transport layer by the doctor blade coating process;

[0064] Specifically, dissolve the polymer donor in toluene to prepare a donor solution with a concentration of 6 - 8 mg / mL; doctor blade coat the donor solution on the surface of the hole transport layer thin film at 80 - 100 °C at a speed of 40 - 60 mm / s, and the distance between the doctor blade and the hole transport layer thin film is 100 - 150 μm;

[0065] After doctor blade coating, anneal at 80 - 100 °C for 5 - 10 min to obtain a polymer donor thin film.

[0066] S4. In a magnetic field, coat a receptor thin film on the surface of the polymer donor thin film by the doctor blade coating process to form a quasi - planar heterojunction active layer;

[0067] Specifically, dissolve the small - molecule receptor in toluene and add an additive to prepare a receptor solution with a concentration of 9 - 12 mg / mL, where the dosage of the additive is 80 wt% of the dosage of the small - molecule receptor, and the additive is preferably diiodobenzene;

[0068] In a magnetic field where the magnetic field direction is parallel or perpendicular to the polymer donor thin film and the magnetic field intensity is 0.25 - 0.75 T, doctor blade coat the receptor solution on the surface of the polymer donor thin film at 80 - 100 °C at a speed of 60 - 70 mm / s, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm;

[0069] After doctor blade coating, anneal at 80 - 100 °C for 5 - 10 min to obtain a quasi - planar heterojunction active layer.

[0070] S5. Prepare an electron transport layer on the surface of the quasi - planar heterojunction active layer by the doctor blade coating process;

[0071] Specifically, dissolve PNDIT-F3N, PDINN or PFN-Br in ethanol to prepare a solution with a concentration of 1-5 mg / mL;

[0072] Scrape-coat the solution on the surface of the quasi-planar heterojunction active layer at 40-50 °C at a speed of 10-30 mm / s, and the distance between the scraper and the transparent conductive substrate is 100-150 μm; obtain the electron transport layer thin film.

[0073] S6, adopt a vacuum evaporation process to evaporate a metal electrode on the surface of the electron transport layer to obtain an organic solar cell. Among them, the material of the metal electrode can be selected from silver or aluminum.

[0074] In this application, by applying an external magnetic field to adjust the active layer thin film in the wet film state during the scrape-coating process, without other complex post-treatment operations, it can be compatible with existing printing technologies, has high repeatability, is suitable for the preparation of large-area devices, and has important value for the preparation of high-performance organic solar cells.

[0075] Among them, through magnetic field-assisted means, a good phase separation scale can be induced between the donor and acceptor, optimizing the penetration process of the acceptor solution into the donor thin film during the deposition process. Without adding additional components and avoiding cumbersome post-treatment, an active layer thin film with fewer defects and more uniformity can be formed, which is beneficial to the dissociation and transport of holes and electrons, and thus improves the photoelectric conversion efficiency of organic solar cells.

[0076] The following further illustrates this application through examples.

[0077] Example 1

[0078] S1, ultrasonically clean an ITO conductive glass sheet (1.5 cm × 1.5 cm) with a cleaning agent, deionized water, and isopropanol for 30 minutes each, dry it with nitrogen, and place it in a UV light cleaning machine for surface treatment for 30 minutes;

[0079] S2, dissolve 2PACZ in methanol to prepare a solution with a concentration of 3 mg / mL; heat the ITO glass substrate to 55 °C, first scrape-coat this solution on the ITO glass substrate at a speed of 30 mm / s, and the distance between the scraper and the glass substrate is 150 μm; then scrape-coat the methanol solution of 2PACZ on the ITO glass substrate coated with PEDOT:PSS at a speed of 30 mm / s, and the distance between the scraper and the glass substrate is 150 μm; then heat it to 180 °C in air and keep it warm for 20 minutes for annealing treatment to obtain a hole transport layer thin film with a thickness of 30 nm.

[0080] S3. Dissolve the polymer donor PM6 in toluene to prepare a donor solution with a concentration of 9 mg / mL, and stir it at 90 °C for 5 hours; heat the ITO glass substrate to 100 °C, and doctor-blade coat the donor solution on the hole transport layer film at a speed of 60 mm / s. The distance between the doctor blade and the substrate is 130 μm to form a donor film with a thickness of 70 nm.

[0081] S4. Dissolve the small molecule acceptor BTP-eC9 in toluene to prepare an acceptor solution with a concentration of 11 mg / mL. Mix it with diiodobenzene and stir at 80 °C for 5 hours, where the dosage of diiodobenzene is 80% of the dosage of BTP-eC9; heat the ITO glass substrate to 100 °C, and doctor-blade coat the dissolved acceptor solution on the donor film at a speed of 65 mm / s under an external magnetic field to form a quasi-planar heterojunction active layer. The magnetic field direction is parallel to the ITO glass substrate, the magnetic field strength is 0.5 T, and the distance between the doctor blade and the substrate is 140 μm.

[0082] S5. Dissolve PNDIT-F3N in ethanol and stir at room temperature for 24 hours to prepare a solution with a concentration of 2 mg / mL. Heat the ITO glass substrate to 50 °C, and doctor-blade coat this solution on the quasi-planar heterojunction active layer at a speed of 30 mm / s. The distance between the doctor blade and the glass substrate is 130 μm to form an electron transport layer with a thickness of 25 nm.

[0083] S6. Evaporate a 100-nm-thick silver metal layer on the surface of the electron transport layer by vacuum thermal evaporation process as the electrode, thereby obtaining an organic solar cell with an effective area of 0.04 cm 2 ².

[0084] Example 2

[0085] The difference between Example 2 and Example 1 is that in step S4, the direction of the magnetic field is perpendicular to the ITO glass substrate, and the rest are the same as in Example 1.

[0086] Example 3

[0087] The difference between Example 3 and Example 1 is that in step S4, the small molecule acceptor is L8-BO, and the rest are the same as in Example 1.

[0088] Example 4

[0089] The difference between Example 4 and Example 1 is that in step S4, the small molecule acceptor is L8-BO, and the direction of the magnetic field is perpendicular to the ITO glass substrate, and the rest are the same as in Example 1.

[0090] Example 5

[0091] The difference between Example 5 and Example 1 is that in step S3, the polymer donor is D18, and the rest are the same as in Example 1.

[0092] Example 6

[0093] The difference between Example 6 and Example 1 is that in step S3, the polymer donor is D18, and the direction of the magnetic field is perpendicular to the ITO glass substrate, and the rest are the same as in Example 1.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that in step S4, there is no externally applied magnetic field, and the rest are the same as in Example 1.

[0096] Comparative Example 2

[0097] The difference between Comparative Example 1 and Example 3 is that in step S4, there is no externally applied magnetic field, and the rest are the same as in Example 3.

[0098] Comparative Example 3

[0099] The difference between Comparative Example 3 and Example 5 is that in step S4, there is no externally applied magnetic field, and the rest are the same as in Example 5.

[0100] The optoelectronic properties of the organic solar cells prepared in Examples 1-6 and Comparative Examples 1-3 were tested. The specific method was as follows: Under the simulated sunlight irradiation with a light source of AM1.5G and a light intensity of 100 mW / cm 2 , the short-circuit current density-open circuit voltage curve of the organic solar cell was tested.

[0101] The short-circuit current density-open circuit voltage curves of Example 1, Example 2 and Comparative Example 1 are as shown in Figure 1 shown. It can be seen from Figure 1 that using the same quasi-planar heterojunction active layer PM6 / BTP-eC9, the current density of the organic solar cell prepared by applying a magnetic field is higher than that of the organic solar cell prepared without a magnetic field at the same voltage.

[0102] The short-circuit current density-open circuit voltage curves of Example 3, Example 4 and Comparative Example 2 are as shown in Figure 2 shown. It can be seen from Figure 2 that using the same quasi-planar heterojunction active layer PM6 / L8-BO, the current density of the organic solar cell prepared by applying a magnetic field is higher than that of the organic solar cell prepared without a magnetic field at the same voltage.

[0103] The short-circuit current density-open circuit voltage curves of Example 5, Example 6 and Comparative Example 3 are as shown in Figure 3 shown. It can be seen from Figure 3 that using the same quasi-planar heterojunction active layer D18 / L8-BO, the current density of the organic solar cell prepared by applying a magnetic field is higher than that of the organic solar cell prepared without a magnetic field at the same voltage.

[0104] The microscopic morphology of the active layer films of the organic solar cells of Example 4 and Comparative Example 2 was evaluated using a transmission electron microscope, and their SEM images are as Figure 4 shown. Among them, Figure 4 the left image in the middle is the SEM image of the active layer film of Comparative Example 2, Figure 4 and the right image in the middle is the SEM image of the active layer film of Example 4.

[0105] From Figure 4 it can be seen that there are obvious differences in the crystallinity of the two active layers. The active layer film prepared under the magnetic field condition in Example 4 has a greater crystallinity, and the distribution is uniform and more continuous. This is because in Example 4, the magnetic field-assisted method can induce a good phase separation scale between the donor and acceptor, optimize the penetration process of the acceptor solution into the donor film during the deposition process, and form an active layer film with fewer defect states and more uniformity. This more continuous network structure is conducive to charge transport, thereby improving the photoelectric conversion efficiency of the organic solar cell.

[0106] The external quantum efficiency (EQE) spectra of the organic solar cells of Example 4 and Comparative Example 2 were tested, and the results are as Figure 5 shown. From Figure 5 it can be seen that compared with Comparative Example 2, Example 4 has a greater improvement in light response both in the long wavelength band and in the short wavelength band, indicating that the example has a more effective light response and further improves the light utilization efficiency.

[0107] The photoelectric performance test data of the organic solar cells prepared in Examples 1-6 and Comparative Examples 1-3 are shown in Table 1.

[0108] Table 1 Photoelectric performance test data of organic solar cells

[0109]

[0110]

[0111] From Table 1, it can be seen that for the quasi-planar heterojunction organic solar cell constructed by the present application with the assistance of an external magnetic field, compared with the quasi-planar heterojunction organic solar cell without a magnetic field in the comparative example, its short-circuit current density and fill factor show an increasing trend. This is because the magnetic field assistance improves the influence of natural convection in the active layer solution on the film during the doctor blade coating process, forming a film with fewer defect states, which is conducive to charge transport and diffusion to the electrodes. Among them, the magnetic field treatment with a magnetic field intensity of 0.25-0.75 T and a direction perpendicular to the substrate direction has the best effect, and its energy conversion efficiency reaches 18.51%, indicating that the preparation method of the present application effectively improves the device performance of the organic solar cell.

[0112] Although the present application has been described in detail in this specification with general descriptions and specific embodiments, modifications or improvements can be made to it based on the present application, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present application all fall within the scope of protection required by the present application.

Claims

1. An organic solar cell with a large-area uniform active layer, characterized in that, It includes, from bottom to top, a transparent conductive substrate, a hole transport layer, a quasi-planar heterojunction active layer, an electron transport layer, and a metal electrode; The quasi-planar heterojunction active layer includes a polymer donor thin film and a small molecule acceptor thin film; the polymer donor thin film is deposited on the hole transport layer by a blade coating process, and the small molecule acceptor thin film is deposited on the polymer donor thin film by a blade coating process under an external magnetic field.

2. The organic solar cell according to claim 1, characterized in that, The polymer donor includes any one of PM6, D18, or D18-Cl; the thickness of the polymer donor thin film is 60 - 90 nm; The small molecule acceptor includes any one of L8-BO, BTP-eC9, or Y6.

3. The organic solar cell according to claim 1, characterized in that, The hole transport layer is a composite thin film of PEDOT:PSS and 2PACZ, and its thickness is 15 - 30 nm; The electron transport layer is any one of PNDIT-F3N, PDINN, or PFN-Br thin films, and its thickness is 15 - 25 nm; The metal electrode is Ag or Al, and its thickness is 85 - 100 nm.

4. The method for preparing an organic solar cell according to claim 1, wherein It includes: S1, Prepare a transparent conductive substrate; S2, Prepare a hole transport layer on the transparent conductive substrate by a blade coating process; S3, Prepare a polymer donor thin film on the surface of the hole transport layer by a blade coating process; S4, In a magnetic field, coat a receptor thin film on the surface of the polymer donor thin film by a blade coating process to form a quasi-planar heterojunction active layer; S5, Prepare an electron transport layer on the surface of the quasi-planar heterojunction active layer by a blade coating process; S6, Adopt a vacuum evaporation process to evaporate a metal electrode on the surface of the electron transport layer to obtain an organic solar cell.

5. The preparation method according to claim 4, characterized in that, In step S3, dissolve the polymer donor in toluene to prepare a donor solution with a concentration of 6 - 8 mg / mL; Perform blade coating on the surface of the hole transport layer thin film with the donor solution at a speed of 40 - 60 mm / s at 80 - 100 °C, and the distance between the blade and the hole transport layer thin film is 100 - 150 μm; After blade coating, anneal at 80 - 100 °C for 5 - 10 min to obtain the polymer donor thin film.

6. The preparation method according to claim 4, characterized in that In S4, the direction of the magnetic field is parallel or perpendicular to the polymer donor thin film, and the magnetic field strength is 0.25 - 0.75 T.

7. The preparation method according to claim 6, characterized in that, In step S4, dissolve the small molecule acceptor in toluene and add an additive to prepare a receptor solution with a concentration of 9 - 12 mg / mL, where the dosage of the additive is 80 wt% of the dosage of the small molecule acceptor; Perform blade coating on the surface of the polymer donor thin film with the receptor solution at a speed of 60 - 70 mm / s at 80 - 100 °C, and the distance between the blade and the transparent conductive substrate is 100 - 150 μm; After blade coating, anneal at 80 - 100 °C for 5 - 10 min to obtain the quasi-planar heterojunction active layer.

8. The preparation method according to claim 7, wherein The additive is diiodobenzene.

9. The preparation method according to claim 4, wherein In step S2, dissolve 2PACZ in methanol to prepare a solution with a concentration of 1 - 5 mg / mL; At 40 - 65 °C, first perform blade coating on the surface of the transparent conductive substrate with PEDOT:PSS at a speed of 10 - 30 mm / s, and the distance between the blade and the transparent conductive substrate is 100 - 150 μm; Then, the solution is doctor-bladed on the surface of the transparent conductive substrate coated with PEDOT:PSS at a speed of 10 - 30 mm / s, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm; After doctor-blading, annealing is carried out at 150 - 200 °C for 15 - 20 min to obtain the hole transport layer film.

10. The preparation method according to claim 4, characterized in that, In step S5, PNDIT-F3N, PDINN or PFN-Br is dissolved in ethanol to prepare a solution with a concentration of 1 - 5 mg / mL; The solution is doctor-bladed on the surface of the quasi-planar heterojunction active layer at a speed of 10 - 30 mm / s at 40 - 50 °C, and the distance between the doctor blade and the transparent conductive substrate is 100 - 150 μm; The electron transport layer film is obtained.

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