A flexible active layer of a polymer-toughened organic solar cell and a method of preparing the same
By introducing a gradient distribution of polymer donor PM6 and non-fullerene acceptor BTP-eC9 into the active layer of a flexible organic solar cell, the charge transport obstacle caused by the introduction of polymer elastomers is solved, improving the photoelectric conversion efficiency and mechanical stability of the device, making it suitable for large-scale commercial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGXI NORMAL UNIV
- Filing Date
- 2023-10-19
- Publication Date
- 2026-06-26
AI Technical Summary
In the prior art, although the introduction of polymer elastomers has improved the mechanical stability of flexible organic solar cells, it has also hindered charge transport and reduced the photoelectric conversion efficiency of the devices.
By introducing 0–20 wt% of polymer donor PM6 into the active layer, and taking advantage of its compatibility difference with the non-fullerene acceptor small molecule BTP-eC9, the deposition process is optimized to achieve a gradient distribution of donor and acceptor. The active layer is prepared by a scraping process, and the cathode is prepared by vacuum thermal evaporation to form a toughened quasi-planar heterojunction.
It improves the energy conversion efficiency and mechanical stability of flexible organic solar cells, enhances the bending resistance of the devices, and is suitable for large-area printing fabrication and commercial use.
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Figure CN117355154B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic solar cell and device fabrication technology, specifically to an active layer of a polymer-toughened flexible organic solar cell and its fabrication method. Background Technology
[0002] Organic solar cells possess advantages such as light weight, low-temperature solution processing, and flexible large-area fabrication, making them a promising candidate for power devices in future portable and wearable electronic devices (such as smartwatches and bio / medical sensors). Currently, thanks to significant efforts in the synthesis of active layer materials, the design of flexible substrates and transparent electrodes, the photoelectric conversion efficiency (PCE) of flexible organic solar cells has reached over 16%, meeting the efficiency requirements for practical applications (Nat. Mater. 2022, 21, 656; J. Am. Chem. Soc. 2022, 144, 4699).
[0003] For flexible organic solar cells, high PCE (Power Conversion Efficiency) is essential, along with good mechanical stability. Currently, a common method to improve the mechanical properties of flexible organic solar cells is to introduce an appropriate amount of polymer elastomer as a toughening agent. However, while the introduction of polymer elastomers improves the mechanical stability of flexible organic solar cells to some extent, the aggregation of the insulating elastomer hinders charge transport, increases charge recombination losses, and leads to a decrease in the device's PCE (Adv. Mater. 2021, 33, 2106732; Macromolecules 54, 2021, 3907). Therefore, further improving the power conversion efficiency of organic solar cells remains a key research focus. Summary of the Invention
[0004] Based on this, the present invention provides an active layer of a polymer-toughened flexible organic solar cell and its preparation method, in order to solve the technical problem that the introduction of polymer elastomers in existing flexible organic solar cells leads to a decrease in the device PCE.
[0005] To achieve the above objectives, the present invention provides a method for preparing the active layer of a polymer-toughened flexible organic solar cell, comprising the following steps:
[0006] 1) Dissolve the polymer donor PM6 in toluene to prepare a donor solution of 5-10 mg / ml;
[0007] 2) Dissolve the non-fullerene receptor small molecule BTP-eC9 in toluene to prepare a solution of 5-10 mg / ml, add 0-20 wt% of polymer donor PM6 (based on the amount of non-fullerene receptor small molecule BTP-eC9), and then add 10 mg / ml of 1,3-dibromo-5-chlorobenzene. Stir at 60-80℃ for 3-4 h to form the receptor solution.
[0008] 3) The donor solution and acceptor solution were coated on the surface of the hole transport layer of the flexible organic solar cell in two separate applications. After each coating, the layer was annealed at 80-120℃ for 8-10 minutes to obtain the active layer of the flexible organic solar cell based on polymer toughening.
[0009] In the above method, when the amount of polymer donor PM6 in step 2) is 0%, the resulting active layer structure is a quasi-planar heterojunction (PPHJ); when the amount of polymer donor PM6 is greater than 0%, the resulting structure is a toughened quasi-planar heterojunction (Toughened-PPHJ). For the specific structure of the active layer, please refer to [link to relevant documentation]. Figure 1 As shown. Further, in step 2), the amount of polymer donor PM6 is preferably 5-10 wt%.
[0010] As a further preferred embodiment of the present invention, the molecular formulas of the polymer donor PM6 and the non-fullerene acceptor small molecule BTP-eC9 are as follows: (a) and (b) respectively:
[0011]
[0012] As a further preferred technical solution of the present invention, in step 3), both the donor solution and the acceptor solution are coated by a blade coating process, and the blade coating speed is 10-50 mm / s.
[0013] According to another aspect of the present invention, the present invention also provides an active layer for a flexible organic solar cell, said active layer being prepared by a method for preparing an active layer for a polymer-toughened flexible organic solar cell.
[0014] According to another aspect of the present invention, the present invention also provides a method for preparing a flexible organic solar cell, which includes the following steps:
[0015] S1. Clean the ITO conductive film;
[0016] S2. Coating poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid onto the ITO surface of the ITO conductive film and annealing it at 120-180℃ for 15-30 minutes to obtain the PEDOT:PSS hole transport layer.
[0017] S3. An active layer is prepared on the surface of the PEDOT:PSS hole transport layer using the above-mentioned method for preparing the active layer of a polymer-toughened flexible organic solar cell.
[0018] S4. Dissolve 3,3'-(1,3,8,10-tetraanthrone[2,1,9-DEF:6,5,10-D'E'F']diisoquinoline-2,9(1H,3H,8H,10H)-diyl)bis(N,N-dimethylpropane-1-amine oxide) in methanol to prepare a solution of 2-3 mg / ml. Stir at room temperature for 3-4 hours and coat the solution onto the surface of the active layer to obtain the PDINO electron transport layer.
[0019] S5. Conductive metal is thermally deposited on the surface of the PDINO electron transport layer as a cathode, and finally a flexible organic solar cell is obtained.
[0020] As a further preferred technical solution of the present invention, the ITO conductive film includes a polyethylene terephthalate substrate and an indium tin oxide anode, the thickness of the substrate being 0.5-10 μm and the thickness of the anode being 120-180 nm.
[0021] As a further preferred embodiment of the present invention, the thickness of the PEDOT:PSS hole transport layer is 5-15 nm.
[0022] As a further preferred embodiment of the present invention, the thickness of the PDINO electron transport layer is 5–15 nm.
[0023] As a further preferred embodiment of the present invention, the cathode is a 90-100 nm thick layer of metallic silver.
[0024] As a further preferred technical solution of the present invention, the PEDOT:PSS hole transport layer, active layer and PDINO electron transport layer are all coated by a blade coating process.
[0025] Preferably, the flexible organic solar cell structure of the present invention is: PET / ITO / PEDOT:PSS / PM6 / / BTP-eC9:0wt%~20wt%PM6 / PDINO / Ag.
[0026] In the preparation method of the active layer of the present invention, the dilution of the acceptor solution by the polymer donor PM6 of 0-20 wt% is used to inhibit the excessive crystallization of the acceptor. By taking advantage of the compatibility difference between the donor and the acceptor, the dissolution and penetration process of the upper solution to the lower donor film during the deposition process is optimized, and the gradient distribution of the donor and acceptor in the active layer is spontaneously induced, thereby synergistically improving the energy conversion efficiency and mechanical stability of the flexible organic solar cell. This provides a guiding idea for the future preparation of high-efficiency flexible organic solar cells.
[0027] The flexible organic solar cell of this invention adopts a forward structure. Its fabrication method, except for the cathode which is prepared by vacuum thermal evaporation, involves coating processes for all other layers (active layer, anode interface layer, and cathode interface layer), preferably using a blade coating process completed in air. This sequential coating method is simple, controllable, and allows for large-area printing fabrication of organic solar cells, facilitating their large-scale commercial application. Attached Figure Description
[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0029] Figure 1 This is a schematic diagram of the donor-acceptor distribution in the active layer of the flexible organic solar cells prepared in Comparative Example 1, Example 1, and Example 2.
[0030] Figure 2 Current (JSC)-voltage (VOC) curves of the flexible organic solar cells prepared in Comparative Examples 1, 1, and 2;
[0031] Figure 3 The stress-strain curves of the active layer films of bulk heterojunction (BHJ), quasi-planar heterojunction (PPHJ), and toughened quasi-planar heterojunction (Toughened-PPHJ) in the flexible organic solar cells prepared in Comparative Examples 1, 1, and 2 are shown.
[0032] Figure 4 Mechanical stability curves of flexible organic solar cells prepared in Comparative Examples 1, 1, and 2.
[0033] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0035] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.
[0036] In the following examples and comparative examples, the blade coating process was performed in air; the molecular formulas of the polymer donor PM6 and the non-fullerene acceptor small molecule BTP-eC9 are shown in formulas (a) and (b) below, respectively:
[0037]
[0038] Comparative Example 1
[0039] The comparison includes the following steps:
[0040] (1) Prepare a polydimethylsiloxane (PDMS) solution by mixing commercially purchased A:B glue in a ratio of 9:1. Remove air bubbles from the solution by vacuum filtration at room temperature. Then, adhere the ITO conductive film with polyethylene terephthalate (PET) as the substrate onto a high-transmittance glass with PDMS. Heat at 90-100℃ for 10-15 minutes to crosslink and cure the PDMS. Clean the substrate by ultrasonic cleaning with detergent, deionized water, and isopropanol for 15-20 minutes in sequence. Then, blow it dry with nitrogen and treat it with microwave plasma for 3-5 minutes to obtain a clean Glass / PET-ITO substrate.
[0041] (2) PEDOT:PSS hole transport layer (anode interface layer) was prepared by blade coating process: PEDOT:PSS hole transport layer material (CLEVIOSTM PVP AI 4083) was coated on the ITO (cathode) surface at a blade coating speed of 20-40 mm / s, the Glass / PET-ITO substrate heating temperature was 40-60℃, and the distance between the blade and the Glass / PET-ITO substrate was 10-20 μm. Then, the hole transport layer was annealed at 150-180℃ for 20-25 minutes to obtain a 15-30 nm thick PEDOT:PSS hole transport layer.
[0042] (3) Preparation of the active layer using a doctor blade coating process: PM6 and BTP-eC9 were dissolved together in toluene at a mass ratio of 1:1.2 and a total mass of 17.6 mg / ml. 10 mg / ml of 1,3-dibromo-5-chlorobenzene (DBCl) was added to form a donor-acceptor blend solution. The mixture was stirred at 65-80°C for 3-4 hours. Then, the donor-acceptor blend solution was coated on the surface of the PEDOT:PSS hole transport layer at a doctor blade coating speed of 30-50 mm / s, a Glass / PET-ITO substrate temperature of 65-80°C, and a distance of 60-80 μm between the doctor blade and the Glass / PET-ITO substrate. The mixture was then annealed at 100-120°C for 10-15 minutes to form a bulk heterojunction (BHJ) active layer.
[0043] (4) PDINO electron transport layer (cathode interface layer) is prepared by blade coating process: PDINO is dissolved in methanol solution to prepare a solution of 3 mg / ml. Stir at room temperature for 3 to 6 hours to fully dissolve it. Then, the solution is coated on the surface of the active layer at a blade coating speed of 15 to 30 mm / s, the temperature of the Glass / PET-ITO substrate is 40 to 50 °C, and the distance between the blade and the Glass / PET-ITO substrate is 50 to 70 μm to prepare a 15 to 30 nm thick PDINO electron transport layer.
[0044] (5) Silver electrode is prepared by vacuum thermal evaporation process: a layer of silver with a thickness of 100-120 nm is thermally deposited on the surface of PDINO electron transport layer as a cathode, thereby obtaining a flexible organic solar cell.
[0045] (6) Finally, the flexible organic solar cell is peeled off the glass to complete the fabrication of the bulk heterojunction (BHJ) type flexible organic solar cell.
[0046] Example 1
[0047] This embodiment 1 includes the following steps:
[0048] (1) Prepare a polydimethylsiloxane (PDMS) solution by mixing commercially purchased A:B glue in a ratio of 9:1. Remove air bubbles from the solution by vacuum filtration at room temperature. Then, adhere the ITO conductive film with polyethylene terephthalate (PET) as the substrate onto a high-transmittance glass with PDMS. Heat at 90-100℃ for 10-15 minutes to crosslink and cure the PDMS to obtain the substrate. Clean the substrate by ultrasonic cleaning with detergent, deionized water, and isopropanol for 15-20 minutes in sequence. Then, blow it dry with nitrogen and treat it with microwave plasma for 3-5 minutes to obtain a clean Glass / PET / ITO substrate.
[0049] (2) PEDOT:PSS hole transport layer (anodic interface layer) was prepared by blade coating process: PEDOT:PSS (CLEVIOSTM PVP AI 4083) hole transport layer material was coated on the ITO surface at a blade coating speed of 20-40 mm / s, the Glass / PET-ITO substrate temperature was 40-60℃, and the distance between the blade and the Glass / PET-ITO substrate was 10-20 μm. Then, the hole transport layer was annealed at 150-180℃ for 20-25 minutes to obtain a 15-30 nm thick PEDOT:PSS hole transport layer.
[0050] (3) The polymer donor PM6 was dissolved in toluene to prepare a donor solution of 10 mg / ml; the non-fullerene acceptor small molecule BTP-eC9 was dissolved in toluene to prepare a solution of 10 mg / ml, and 10 mg / ml of 1,3-dibromo-5-chlorobenzene (DBCl) was added. The solution was stirred at 65-80°C for 3-4 hours to form an acceptor solution. Then, the donor and acceptor solutions were sequentially coated on the surface of the PEDOT:PSS hole transport layer at a coating speed of 30-50 mm / s, a Glass / PET-ITO substrate temperature of 65-80°C, and a distance of 60-80 μm between the scraper and the Glass / PET-ITO substrate. After each coating, the solution was annealed at 100-120°C for 10-15 minutes to form a quasi-planar heterojunction (PPHJ) active layer.
[0051] (4) Preparation of PDINO electron transport layer (cathode interface layer) by blade coating process: PDINO is dissolved in methanol solution to prepare a 3 mg / ml solution. Stir at room temperature for 3 to 6 hours to fully dissolve it. Then, the solution is coated on the surface of the active layer at a blade coating speed of 15 to 30 mm / s, the Glass / PET-ITO substrate temperature is 40 to 50 °C, and the distance between the blade and the Glass / PET-ITO substrate is 50 to 70 μm to prepare an electron transport layer with a thickness of 15 to 30 nm.
[0052] (5) A silver electrode is prepared by vacuum thermal evaporation process. A layer of silver with a thickness of 100-120 nm is thermally deposited on the surface of the electron transport layer as an electrode, thereby obtaining a flexible organic solar cell.
[0053] (6) Finally, the flexible organic solar cell is peeled off the glass to complete the fabrication of the quasi-planar heterojunction (PPHJ) flexible organic solar cell.
[0054] Example 2
[0055] This embodiment 2 includes the following steps:
[0056] (1) Prepare a polydimethylsiloxane (PDMS) solution by mixing commercially purchased A:B glue in a ratio of 9:1. Remove air bubbles from the solution by vacuum filtration at room temperature. Then, adhere the ITO conductive film with polyethylene terephthalate (PET) as the substrate onto a high-transmittance glass with PDMS. Heat at 90-100℃ for 10-15 minutes to crosslink and cure the PDMS to obtain the substrate. Clean the substrate by ultrasonic cleaning with detergent, deionized water, and isopropanol for 15-20 minutes in sequence. Then, blow it dry with nitrogen and treat it with microwave plasma for 3-5 minutes to obtain a clean Glass / PET / ITO substrate.
[0057] (2) PEDOT:PSS hole transport layer (anodic interface layer) was prepared by blade coating process: PEDOT:PSS hole transport layer material (CLEVIOSTM PVP AI 4083) was coated on the ITO surface at a blade coating speed of 20-40 mm / s, the Glass / PET-ITO substrate temperature was 40-60℃, and the distance between the blade and the Glass / PET-ITO substrate was 10-20 μm. Then, the hole transport layer was annealed at 150-180℃ for 20-25 minutes to obtain a 15-30 nm thick PEDOT:PSS hole transport layer.
[0058] (3) The polymer donor PM6 was dissolved in toluene to prepare a donor solution of 10 mg / ml; 10 wt% PM6 was added to the non-fullerene acceptor small molecule BTP-eC9 and dissolved in toluene to prepare a solution of 10 mg / ml, and then 10 mg / ml of 1,3-dibromo-5-chlorobenzene (DBCl) was added. The mixture was stirred at 65-80°C for 3-4 hours to form an acceptor solution; then, the donor and acceptor solutions were sequentially coated on the surface of the PEDOT:PSS hole transport layer at a scraping speed of 30-50 mm / s, a Glass / PET-ITO substrate temperature of 65-80°C, and a distance of 60-80 μm between the scraper and the Glass / PET-ITO substrate. After each coating, the solution was annealed at 100-120°C for 10-15 minutes to form a toughened quasi-planar heterojunction (Toughened-PPHJ) active layer.
[0059] (4) PDINO electron transport layer (cathode interface layer) is prepared by blade coating process: PDINO is dissolved in methanol solution to prepare a 3 mg / ml solution. Stir at room temperature for 3 to 6 hours to fully dissolve it. Then, the solution is coated on the surface of the active layer at a blade coating speed of 15 to 30 mm / s, the Glass / PET-ITO substrate temperature is 40 to 50 °C, and the distance between the blade and the Glass / PET-ITO substrate is 50 to 70 μm to prepare an electron transport layer with a thickness of 15 to 30 nm.
[0060] (5) A silver electrode is prepared by vacuum thermal evaporation process. A layer of silver with a thickness of 100-120 nm is thermally deposited on the surface of the electron transport layer as an electrode, thereby obtaining a flexible organic solar cell.
[0061] (6) Finally, the flexible organic solar cell is peeled off the glass to complete the fabrication of the toughened-PPHJ flexible organic solar cell.
[0062] The difference between Comparative Example 1, Example 1, and Example 2 above lies in the different distribution of acceptors in the active layer, as shown below. Figure 1As shown, a) is the bulk heterojunction (BHJ) active layer of Comparative Example 1, where donor and acceptor molecules are randomly distributed in the active layer film; b) is the quasi-planar heterojunction (PPHJ) active layer of Example 1, where donors are enriched at the bottom layer and acceptors at the top layer; c) is the toughened quasi-planar heterojunction (Toughened-PPHJ) active layer of Example 2, where donors and acceptors are distributed in a gradient pattern in the active layer film. It is evident that the vertical distribution of donors and acceptors in the three films exhibits significant differences, leading to substantial differences in performance.
[0063] Photovoltaic performance testing of flexible organic solar cell devices:
[0064] The light source is AM1.5G, and the sunlight intensity is 100 Mw / cm². 2 The simulated sunlight was tested and calibrated using a standard silicon cell; the testing instrument was a Keithley 2400Source Meter.
[0065] The device current (J / m²) of the solar cells based on BHJ, PPHJ, and Toughened-PPHJ in Comparative Example 1, Example 1, and Example 2 was obtained through testing. SC - Voltage (V) OC ) curve, such as Figure 2 As shown, the performance of the device obtained from it is shown in Table 1: including open-circuit voltage (J). SC ), short-circuit current (V) OC ), fill factor (FF) and power conversion efficiency (PCE), where: PCE = V OC *J SC *FF / P in (P in (The intensity of the incident light).
[0066] Table 1
[0067] Active layer type <![CDATA[V OC [V]]> <![CDATA[J SC [mA cm -2 ]]> FF[%] PCE [%] Comparative Example 1 BHJ 0.842 24.77 71.43 14.90 Example 1 PPHJ 0.830 25.31 72.14 15.15 Example 2 Toughened-PPHJ 0.831 25.68 72.22 15.42
[0068] As shown in the table above, the device with a precisely constructed toughened-PPHJ active layer benefits from the gradient distribution of donors and acceptors in the vertical direction of the active layer, resulting in improved short-circuit current and fill factor, and an energy conversion efficiency of 15.42%. This demonstrates that the method of the present invention successfully improves the performance of flexible organic solar cell devices.
[0069] Stress-strain curve testing of the active layer thin film in flexible organic solar cells:
[0070] The testing instruments were a polarizing microscope (ECLIPSE LV100N POL, Nikon) and a custom-designed stretching stage.
[0071] Tensile tests were performed on the three active layer films (BHJ, PPHJ, and Toughened-PPHJ) obtained in step (3) of Comparative Example 1, Example 1, and Example 2. The test results are as follows: Figure 3 As shown. By comparison Figure 3 The stress-strain curves show that the gradient heterojunction film has a higher fracture initiation strain (COS). The fracture elongation (COS) of the Toughened-PPHJ active layer film is 11.0%, which is significantly better than the 5.5% of the BHJ active layer film, indicating that the method successfully improves the mechanical properties of the film.
[0072] Bending stability test of flexible organic solar cell devices:
[0073] The testing instrument is a flexible device bending tester, model HW series.
[0074] The three types of flexible batteries, BHJ, PPHJ, and Toughened-PPHJ, obtained in step (6) of Comparative Example 1, Example 1, and Example 2, were subjected to bending performance tests. The test results are as follows: Figure 4 The Toughened-PPHJ type flexible organic solar cell, under a curvature radius of 5 mm, maintains a PCE of over 92% after 1000 cyclic bending cycles, significantly outperforming the other two types of flexible cells. Under the same test conditions, the PCE of the PPHJ type flexible organic solar cell is close to 90% of the initial value, while the PCE of the BHJ type flexible organic solar cell is less than 85%, indicating that the method of this invention successfully improves the bending resistance of flexible devices. Specifically, for the quasi-planar heterojunction (P-PHJ) flexible organic solar cell prepared by sequential coating process, the structural characteristic of donor / acceptor (D / A) enrichment at both ends is beneficial to PCE improvement. However, for the high-efficiency polymer small molecule system, the enrichment of acceptor small molecules in the upper layer results in slightly lower mechanical stability than the Toughened-PPHJ type flexible organic solar cell, but significantly higher than the BHJ type flexible organic solar cell.
[0075] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.
Claims
1. A method for preparing the active layer of a polymer-toughened flexible organic solar cell, characterized in that, Includes the following steps: 1) Dissolve the polymer donor PM6 in toluene to prepare a donor solution of 5~10 mg / ml; 2) Dissolve the non-fullerene receptor small molecule BTP-eC9 in toluene to prepare a solution of 5-10 mg / ml, add 0-20 wt% of the polymer donor PM6 (based on the amount of non-fullerene receptor small molecule BTP-eC9), and then add 10 mg / ml of 1,3-dibromo-5-chlorobenzene. Stir at 60-80 °C for 3-4 h to form the receptor solution. 3) The donor solution and acceptor solution were coated on the surface of the hole transport layer of the flexible organic solar cell in two separate applications. After each coating, the layer was annealed at 80-120 °C for 8-10 minutes to obtain the active layer of the polymer-toughened flexible organic solar cell.
2. The method for preparing the active layer of a polymer-toughened flexible organic solar cell according to claim 1, characterized in that, The molecular formulas of the polymer donor PM6 and the non-fullerene acceptor small molecule BTP-eC9 are as follows (a) and (b): 。 3. The method for preparing the active layer of a polymer-toughened flexible organic solar cell according to claim 1, characterized in that, In step 3), both the donor solution and the acceptor solution are coated by a blade coating process with a thickness of 50 nm and a blade coating speed of 10~50 mm / s.
4. An active layer of a flexible organic solar cell, characterized in that, The active layer is prepared by the method according to any one of claims 1-3.
5. A method for preparing a flexible organic solar cell, characterized in that, Includes the following steps: S1. Clean the ITO conductive film; S2. Coating poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid onto the ITO surface of the ITO conductive film and annealing it at 120-180℃ for 15-30 minutes to obtain the PEDOT:PSS hole transport layer. S3. An active layer is prepared on the surface of the PEDOT:PSS hole transport layer by the method of any one of claims 1-3; S4. Dissolve 3,3'-(1,3,8,10-tetraanthrone[2,1,9-DEF:6,5,10-D'E'F']diisoquinoline-2,9(1H,3H,8H,10H)-diyl)bis(N,N-dimethylpropane-1-amine oxide) in methanol to prepare a solution of 2~3 mg / ml. Stir at room temperature for 3~4 hours and coat the solution onto the surface of the active layer to obtain the PDINO electron transport layer. S5. Conductive metal is thermally deposited on the surface of the PDINO electron transport layer as a cathode, and finally a flexible organic solar cell is obtained.
6. The method for preparing a flexible organic solar cell according to claim 5, characterized in that, The ITO conductive film comprises a polyethylene terephthalate substrate and an indium tin oxide anode, the substrate having a thickness of 0.5~10 μm and the anode having a thickness of 120~180 nm.
7. The method for preparing a flexible organic solar cell according to claim 5, characterized in that, The thickness of the PEDOT:PSS hole transport layer is 5~15 nm.
8. The method for preparing a flexible organic solar cell according to claim 5, characterized in that, The thickness of the PDINO electron transport layer is 5~15 nm.
9. The method for preparing a flexible organic solar cell according to claim 5, characterized in that, The cathode is 90-100 nm thick metallic silver.
10. The method for preparing a flexible organic solar cell according to any one of claims 5-9, characterized in that, The PEDOT:PSS hole transport layer, active layer, and PDINO electron transport layer are all coated using a blade coating process.