Flexible all-polymer solar cell with high fill factor and preparation method thereof

Abstract

The invention belongs to the technical field of new energy, and provides a high-fill-factor flexible all-polymer solar cell and a preparation method thereof, and the solar cell structure sequentially comprises a flexible substrate, an anode layer, a hole transport layer, a polymer donor layer, a polymer acceptor layer, an electron transport layer and a cathode layer from bottom to top. The polymer donor layer and the polymer acceptor layer jointly form the active layer, a layer-by-layer structure with a polymer as a main component is adopted, a fullerene acceptor PCBM or a small molecule acceptor Y6 is introduced into the polymer acceptor layer to serve as a third component, and the filling factor of the all-polymer solar cell is increased, so that the performance of the all-polymer solar cell is improved. The flexible all-polymer solar cell based on the PET flexible substrate has charge transfer capability comparable to that of a rigid ITO substrate and more balanced carrier mobility, and the all-polymer solar cell can show good photoelectric conversion efficiency and long-term stability of devices on the rigid ITO substrate and the flexible PET substrate.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a flexible all-polymer solar cell with a high fill factor and a preparation method thereof. Background Art

[0002] With the modernization of human society, the use of electrical energy is becoming increasingly widespread, and solar energy technology, which directly converts solar energy into electricity, has been a highly developed high-tech. Polymer solar cells have attracted considerable attention due to their many advantages, including low cost, light weight, strong flexibility, translucency, and large fabrication area. With the emergence of high-performance narrow-bandgap small molecule acceptors and wide-bandgap polymer donors, the photoelectric conversion efficiency of polymer solar cells has exceeded 20%. Compared with devices based on small molecule acceptors, all-polymer solar cells with n-type and p-type polymers as the photoactive layer exhibit excellent mechanical durability and stability. These excellent thin-film properties have led to the remarkable development of all-polymer solar cells. In particular, flexible all-polymer solar cells as power supply systems for wearable electronic systems have become a research hotspot in recent years. Currently, the performance of all-polymer solar cells prepared on rigid substrates (ITO) has been greatly improved, but the development of all-polymer solar cells on flexible substrates remains slow. Flexible all-polymer solar cells are a key technology for realizing the future application of organic solar cells in various scenarios. Clearly, how to construct efficient and bend-resistant flexible all-polymer solar cells is a key issue to meet the requirements of future applications. Therefore, how to make all-polymer solar cells on flexible PET substrates exhibit similar charge transfer ability, balanced carrier transport and excellent long-term stability as those on ITO substrates has become a research direction that cannot be ignored. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects in the prior art and provide a flexible all-polymer solar cell with a high fill factor and a preparation method thereof.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a flexible all-polymer solar cell with a high filling factor. The structure of the flexible all-polymer solar cell with a high filling factor is, from bottom to top,: a flexible substrate, an anode layer, a hole transport layer, a polymer donor layer, a polymer acceptor layer, an electron transport layer and a cathode layer.

[0006] Preferably, the material of the flexible substrate is one or more of polyvinyl alcohol, polyester, polyimide and polyethylene naphthalate;

[0007] The material of the anode layer is polyethylene terephthalate;

[0008] The material of the hole transport layer is PEDOT:PSS;

[0009] The thickness of the hole transport layer is 16-35 nm.

[0010] Preferably, the material of the polymer donor layer is PM6; the thickness of the polymer donor layer is 57-65 nm;

[0011] The material of the polymer receptor layer is a PCBM-based material or a Y6-based material;

[0012] When the material of the polymer receptor layer is a PCBM-based material, the PCBM-based material comprises polymer N2200 and PCBM; the mass ratio of the polymer N2200 to PCBM is 6-10:1-3;

[0013] When the material of the polymer receptor layer is a Y6-based material, the Y6-based material comprises polymer N2200 and Y6; the mass ratio of the polymer N2200 to Y6 is 6-10:1-3;

[0014] The thickness of the polymer receptor layer is 55-65 nm.

[0015] Preferably, the material of the electron transport layer is PDINO or LiF; the thickness of the electron transport layer is 8 to 15 nm;

[0016] The material of the cathode layer is Al or Ag; the thickness of the cathode layer is 70-110 nm.

[0017] The present invention also provides a method for preparing the flexible all-polymer solar cell with a high fill factor, comprising the following steps:

[0018] (1) forming an anode layer on one side of the flexible substrate;

[0019] (2) Spin coating the PEDOT:PSS solution on the surface of the anode layer and annealing to obtain a hole transport layer;

[0020] (3) Spin coating the PM6 solution on the surface of the hole transport layer to obtain a polymer donor layer;

[0021] (4) spin coating a polymer receptor layer material solution on the surface of the polymer donor layer to obtain a polymer receptor layer;

[0022] (5) coating an electron transport layer material solution on the surface of the polymer receptor layer to obtain an electron transport layer;

[0023] (6) By evaporating the cathode layer on the surface of the electron transport layer, a flexible all-polymer solar cell with a high fill factor can be obtained.

[0024] Preferably, the volume ratio of PEDOT:PSS to water in the PEDOT:PSS solution in step (2) is 1-2:1-2;

[0025] The spin coating in step (2) is performed at a speed of 3000 to 5000 rpm for 20 to 40 seconds.

[0026] The annealing treatment in step (2) is performed at a temperature of 80 to 120° C. for 5 to 15 minutes.

[0027] Preferably, the concentration of the PM6 solution in step (3) is 5 to 15 mg / mL;

[0028] The spin coating in step (3) is performed at a rotation speed of 1000 to 3000 rpm and for a time of 20 to 40 seconds.

[0029] Preferably, the concentration of the polymer receptor layer material solution in step (4) is 8 to 10 mg / mL;

[0030] The spin coating in step (4) is performed at a rotation speed of 1000 to 3000 rpm and for a time of 20 to 40 seconds.

[0031] Preferably, the concentration of the electron transport layer material solution in step (5) is 1 to 3 mg / mL;

[0032] The coating method in step (5) is spin coating or evaporation;

[0033] When the coating method is spin coating, the spin coating speed is 1000-3000 rpm and the time is 30-50 s;

[0034] When the coating method is evaporation, the vacuum degree of the evaporation is ≤0.0004Pa, and the deposition rate is

[0035] Preferably, the vacuum degree of the evaporation in step (6) is ≤0.0003 Pa, the turntable speed is 4-6 r / min, and the growth rate is 2-4 nm / s.

[0036] The present invention provides a flexible all-polymer solar cell with a high fill factor. The structure of the flexible all-polymer solar cell comprises, from bottom to top, a flexible substrate, an anode layer, a hole transport layer, a polymer donor layer, a polymer acceptor layer, an electron transport layer, and a cathode layer. By optimizing the cell structure, improving the acceptor material composition, and the process flow, the present invention addresses the technical challenges of weak charge transfer capability and unbalanced carrier transport in existing all-polymer solar cells on flexible substrates, effectively improving the fill factor and photoelectric conversion efficiency of flexible all-polymer solar cells.

[0037] In the all-polymer solar cell provided by the present invention, a polymer donor layer and a polymer acceptor layer together constitute an active layer, adopt a layer-by-layer structure mainly composed of polymers, and introduce a fullerene acceptor PCBM or a small molecule acceptor Y6 as a third component into the polymer acceptor layer. By improving the fill factor of the all-polymer solar cell, a flexible all-polymer solar cell based on a PET flexible substrate is achieved, which has a charge transfer capability comparable to that of a rigid ITO substrate and a more balanced carrier mobility, and can meet the requirements of the all-polymer solar cell exhibiting good photoelectric conversion efficiency and long-term stability of the device on both the rigid substrate ITO and the flexible substrate PET.

[0038] Compared with the all-polymer solar cell with only a single polymer receptor, the solar cell of the present invention has the characteristics of simple structure, low material cost, high repeatability, good mechanical properties, and easy maintenance. The prepared all-polymer solar cell shows good photoelectric conversion efficiency and long-term working stability of the device on both rigid ITO glass and flexible PET substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of a flexible all-polymer solar cell with a high fill factor according to the present invention;

[0040] Figure 2 1 is a graph showing the current density-voltage characteristic of the solar cells of Example 1, Example 2 and Comparative Example 1;

[0041] Figure 3 1 is an external quantum efficiency curve of solar cells of Example 1, Example 2 and Comparative Example 1;

[0042] Figure 4 Graphs showing the pure electron current density-voltage characteristic of the solar cells in the dark state of Example 1, Example 2, and Comparative Example 1;

[0043] Figure 5 1 is a graph showing the electron mobility of solar cells of Example 1, Example 2 and Comparative Example 1;

[0044] Figure 6 1 is a graph showing the current density-voltage characteristic curves of the solar cells of Example 1, Comparative Example 2, Example 2 and Comparative Example 3. DETAILED DESCRIPTION

[0045] The present invention provides a flexible all-polymer solar cell with a high filling factor. The structure of the flexible all-polymer solar cell with a high filling factor is, from bottom to top,: a flexible substrate, an anode layer, a hole transport layer, a polymer donor layer, a polymer acceptor layer, an electron transport layer and a cathode layer.

[0046] In the present invention, the material of the flexible substrate is one or more of polyvinyl alcohol, polyester, polyimide and polyethylene naphthalate.

[0047] In the present invention, the material of the anode layer is polyethylene terephthalate.

[0048] In the present invention, the material of the hole transport layer is PEDOT:PSS.

[0049] In the present invention, the thickness of the hole transport layer is preferably 16 to 35 nm, more preferably 20 to 30 nm, and even more preferably 24 to 26 nm.

[0050] In the present invention, the material of the polymer donor layer is preferably PM6; the thickness of the polymer donor layer is preferably 57 to 65 nm, more preferably 58 to 64 nm, and even more preferably 60 to 62 nm.

[0051] In the present invention, the material of the polymer receptor layer is a PCBM-based material or a Y6-based material.

[0052] In the present invention, when the material of the polymer receptor layer is a PCBM-based material, the PCBM-based material comprises polymer N2200 and PCBM; the mass ratio of the polymer N2200 to PCBM is preferably 6-10:1-3, more preferably 7-9:1.5-2.5, and more preferably 7.5-8.5:1.8-2.2; PCBM is specifically PC 61 BM.

[0053] In the present invention, when the material of the polymer receptor layer is a Y6-based material, the Y6-based material comprises polymer N2200 and Y6; the mass ratio of the polymer N2200 and Y6 is preferably 6-10:1-3, more preferably 7-9:1.5-2.5, and more preferably 7.5-8.5:1.8-2.2.

[0054] In the present invention, the thickness of the polymer receptor layer is preferably 55 to 65 nm, more preferably 56 to 64 nm, and even more preferably 58 to 62 nm.

[0055] In the present invention, the material of the electron transport layer is PDINO or LiF; the thickness of the electron transport layer is preferably 8 to 15 nm, more preferably 9 to 14 nm, and even more preferably 10 to 12 nm.

[0056] In the present invention, the material of the cathode layer is Al or Ag; the thickness of the cathode layer is preferably 70 to 110 nm, more preferably 80 to 100 nm, and even more preferably 85 to 95 nm.

[0057] The structural diagram of the flexible all-polymer solar cell with high fill factor of the present invention is as follows Figure 1 As shown; wherein 1 is a flexible substrate, 2 is a hole transport layer, 3 is a polymer donor layer, 4 is a polymer acceptor layer, 5 is an electron transport layer and 6 is a cathode layer.

[0058] The present invention also provides a method for preparing the flexible all-polymer solar cell with a high fill factor, comprising the following steps:

[0059] (1) forming an anode layer on one side of the flexible substrate;

[0060] (2) Spin coating the PEDOT:PSS solution on the surface of the anode layer and annealing to obtain a hole transport layer;

[0061] (3) Spin coating the PM6 solution on the surface of the hole transport layer to obtain a polymer donor layer;

[0062] (4) spin coating a polymer receptor layer material solution on the surface of the polymer donor layer to obtain a polymer receptor layer;

[0063] (5) coating an electron transport layer material solution on the surface of the polymer receptor layer to obtain an electron transport layer;

[0064] (6) By evaporating the cathode layer on the surface of the electron transport layer, a flexible all-polymer solar cell with a high fill factor can be obtained.

[0065] In the present invention, the conductive substrate after forming the anode layer is ultrasonically cleaned in water, acetone and isopropanol in sequence; the time for ultrasonic cleaning in water is preferably 10 to 20 minutes, more preferably 12 to 18 minutes, and more preferably 14 to 16 minutes; the time for ultrasonic cleaning in acetone is preferably 10 to 20 minutes, more preferably 12 to 18 minutes, and more preferably 14 to 16 minutes; the time for ultrasonic cleaning in isopropanol is preferably 10 to 20 minutes, more preferably 12 to 18 minutes, and more preferably 14 to 16 minutes; after cleaning, it is blown dry with nitrogen and cleaned under ultraviolet ozone conditions, and the time for ultraviolet ozone cleaning is preferably 10 to 20 minutes, more preferably 12 to 18 minutes, and more preferably 14 to 16 minutes; after cleaning, the next step is carried out.

[0066] In the present invention, the volume ratio of PEDOT:PSS to water in the PEDOT:PSS solution in step (2) is preferably 1-2:1-2, more preferably 1.2-1.8:1.2-1.8, and more preferably 1.4-1.6:1.4-1.6.

[0067] In the present invention, the spin coating speed in step (2) is preferably 3000-5000 rpm, more preferably 3500-4500 rpm, more preferably 3800-4200 rpm; the time is preferably 20-40 s, more preferably 25-35 s, more preferably 28-32 s.

[0068] In the present invention, the temperature of the annealing treatment in step (2) is preferably 80-120°C, more preferably 85-115°C, and more preferably 90-110°C; the time is preferably 5-15 min, more preferably 6-14 min, and more preferably 8-12 min.

[0069] In the present invention, the concentration of the PM6 solution in step (3) is preferably 5 to 15 mg / mL, more preferably 6 to 14 mg / mL, and even more preferably 8 to 12 mg / mL; the solvent of the PM6 solution is chloroform or chlorobenzene.

[0070] The spin coating atmosphere in step (3) is nitrogen, the rotation speed is preferably 1000-3000 rpm, more preferably 1500-2500 rpm, more preferably 1800-2200 rpm; the time is preferably 20-40 s, more preferably 25-35 s, more preferably 28-32 s.

[0071] In the present invention, the concentration of the polymer receptor layer material solution in step (4) is preferably 8-10 mg / mL, more preferably 8.5-9.5 mg / mL, and more preferably 8.8-9.2 mg / mL; the solvent of the polymer receptor layer material solution is chloroform, chlorobenzene or toluene.

[0072] In the present invention, the spin coating speed in step (4) is preferably 1000-3000 rpm, more preferably 1500-2500 rpm, more preferably 1800-2200 rpm; the time is preferably 20-40 s, more preferably 25-35 s, more preferably 28-32 s.

[0073] In the present invention, the concentration of the electron transport layer material solution in step (5) is preferably 1-3 mg / mL, more preferably 1.5-2.5 mg / mL, and more preferably 1.8-2.2 mg / mL; the solvent of the electron transport layer material solution is methanol.

[0074] In the present invention, the coating method in step (5) is spin coating or evaporation.

[0075] In the present invention, when the coating method is spin coating, the spin coating speed is preferably 1000-3000 rpm, more preferably 1500-2500 rpm, more preferably 1800-2200 rpm; the time is preferably 30-50 s, more preferably 35-45 s, more preferably 38-42 s.

[0076] In the present invention, when the coating method is evaporation, the vacuum degree of the evaporation is preferably ≤0.0004Pa, more preferably ≤0.0003Pa, and more preferably ≤0.0002Pa; the deposition rate is preferably More preferably More preferably

[0077] In the present invention, the vacuum degree of the evaporation in step (6) is preferably ≤0.0003Pa, further preferably ≤0.0002Pa, more preferably ≤0.0001Pa; the turntable speed is preferably 4-6r / min, further preferably 4.5-5.5r / min, more preferably 4.8-5.2r / min; the growth rate is preferably 2-4nm / s, further preferably 2.5-3.5nm / s, more preferably 2.8-3.2nm / s.

[0078] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] All raw materials in the examples, unless otherwise specified, are commercially available. They include: PM6: solid powder, molecular weight 50,000; N2200: solid powder, molecular weight 20,000; PC 61 BM: solid powder, 99.99% purity; Y6: solid powder, 99.99% purity; PEDOT:PSS: liquid, solid content 1.0-1.3%, PEDOT:PSS mass ratio 1:2.5, resistance 500-5000 Ω / cm; PDINO: solid powder, 99.99% purity; LiF: solid powder, 99.99% purity; Deionized water: liquid, 99.99% purity; Acetone: liquid, 99.5% purity; Ethanol, isopropyl alcohol, chloroform, chlorobenzene, methanol, toluene, anisole: liquid, 99.99% purity; Aluminum: solid particles, φ6*6mm, 99.99% purity; Polyethylene terephthalate (PET): solid; Indium tin oxide (ITO): solid.

[0080] The detection instruments used in the embodiment include: using a solar simulator (100 mW cm-2, 1.5 AM) to test the current-voltage (IV) characteristic curve of the device and determine the photovoltaic parameters (VOC, JSC, FF and PCE) of the device; using a commercial quantum efficiency test instrument (QE-R3018, Enli Technology Co., Ltd.) to measure the external quantum efficiency EQE of the device.

[0081] Example 1

[0082] An anode layer is formed on one surface of the flexible substrate. The material of the anode layer is polyethylene terephthalate to obtain a PET (polyethylene terephthalate) conductive substrate. The ultra-thin PET conductive substrate with a thickness of 2.5 μm is cut into approximately 1.5×1.5 cm 2 size; place the PET conductive substrate in deionized water and ultrasonically clean it for 15 minutes; then place it in acetone and ultrasonically clean it for 15 minutes; then place it in isopropanol and ultrasonically clean it for 15 minutes; blow the cleaned PET conductive substrate dry with nitrogen and clean it under ultraviolet ozone conditions for 15 minutes; spin-coat the PEDOT:PSS solution (the volume ratio of PEDOT:PSS and water is 1:1) on the surface of the anode layer at a speed of 4000 rpm and a time of 30 seconds, with a film thickness of 30 nm; then anneal at 100°C for 10 minutes to obtain a hole transport layer; prepare a PM6 solution (the solvent is chloroform, the concentration is 10 mg / mL), and in a nitrogen atmosphere, spin-coat the PM6 solution on the upper surface of the hole transport layer at a speed of 2000 rpm and a time of 30 seconds to a thickness of 60 nm to obtain a polymer donor layer; polymer N2200 and PC 61 BM was weighed in a mass ratio of 8:2 and then dissolved in chlorobenzene to obtain a polymer acceptor layer material solution with a concentration of 8 mg / mL. The polymer acceptor layer material solution was spin-coated on the upper surface of the PM6 polymer donor layer at a speed of 2000 rpm for 30 s to obtain a 60 nm polymer acceptor layer; PDINO was dissolved in methanol to obtain an electron transport layer material solution with a concentration of 2 mg / mL, and then spin-coated on the upper surface of the polymer acceptor layer at a speed of 2000 rpm for 40 s to obtain an electron transport layer with a thickness of 10 nm; high-purity aluminum was used as the cathode material and evaporated in a vacuum evaporation furnace. The component to be processed was placed on the turntable at the top of the furnace chamber with the substrate of the electron transport layer facing down; the formulated amount of evaporation material particles was placed in a tungsten boat; the vacuum degree in the furnace was 0.0003 Pa and the turntable speed was 5 r / min; the growth rate of the cathode layer was set at 3 nm / s during the evaporation process, and the cathode layer thickness was 90 nm; after the evaporation was completed, a flexible all-polymer solar cell with a high filling factor was obtained.

[0083] Example 2

[0084] The difference between Example 2 and Example 1 is that PC 61 Replace BM with Y6, and follow the same steps.

[0085] Comparative Example 1

[0086] The difference between Comparative Example 1 and Example 1 is that no PC is added. 61 BM, the rest of the steps are the same.

[0087] Comparative Example 2

[0088] The difference between Comparative Example 2 and Example 1 is that polyethylene terephthalate is replaced with indium tin oxide (ITO), and the remaining steps are the same.

[0089] Comparative Example 3

[0090] The difference between Comparative Example 3 and Example 2 is that polyethylene terephthalate is replaced with indium tin oxide (ITO), and the remaining steps are the same.

[0091] The solar cells of Example 1, Example 2 and Comparative Example 1 were tested for current density-voltage performance. The results are as follows: Figure 2 shown; from Figure 2 It can be seen that compared with the binary all-polymer solar cells based on PM6 / N2200, the introduction of fullerene acceptor PC 61 The ternary all-polymer solar cells with BM or the introduction of non-fullerene acceptor Y6 showed an improvement in photocurrent due to the increased light absorption. Specifically, based on PM6 / N2200:PC 61 The short-circuit current (Jsc) of the BM system is increased from 7.7 mA / cm 2 Increased to 9.4 mA / cm 2 The short-circuit current of PM6 / N2200:Y6 system is from 7.7mA / cm 2 Increased to 11.4 mA / cm 2 Notably, the fullerene-based ternary device based on PM6 / N2200:PC61BM exhibited a significant improvement in FF on a PET conductive substrate, increasing from 56% to 59%. In contrast, the FF of the device based on the PM6 / N2200:Y6 system on a PET conductive substrate dropped sharply from 56% to 31%. These results indicate that devices based on the PM6 / N2200:Y6 system suffer from severe charge recombination.

[0092] The solar cells of Example 1, Example 2 and Comparative Example 1 were tested for external quantum efficiency. The results are as follows: Figure 3 As shown; it can be seen that compared with the PM6 / N2200 system, PM6 / N2200:Y6 and PM6 / N2200:PC 61The photoresponse of the BM system is improved. For devices based on the PM6 / N2200 material system, the EQE at about 550-650nm comes from the donor polymer PM6. Compared with the PM6 / N2200 device, the EQE value at around 600nm is significantly improved, indicating that in the two ternary devices, the addition of the third component (PC 61 BM or Y6) further improved the exciton dissociation process of the donor phase PM6 material layer, resulting in a significant enhancement of the photocurrent.

[0093] The solar cells of Example 1, Example 2 and Comparative Example 1 were subjected to carrier performance tests. The pure electron current density-voltage characteristic curves in the dark state are shown in FIG. Figure 4 As shown; the electron mobility curve is as Figure 5 shown; from Figure 4 and Figure 5 It can be seen that based on fullerene PC 61 Electron mobility of BM ternary device (μ e ) is significantly higher than the Y6-based ternary device. 61 The carrier transport of BM is isotropic, based on PC 61 μ of BM device e Almost better than the μ of Y6-based devices e Therefore, compared with PM6 / N2200:Y6 (3.02), PM6 / N2200:PC 61 μ of BM device e / μ h The coefficient (1.50) is more balanced. At the same time, the extremely low μh in the PM6 / N2200:Y6 system will prevent the free charge collection efficiency at the electrode, and the electron / hole mobility (μ h / μ e ) further leads to the accumulation of carriers, which easily forms a reverse electric field in the device. The above processes will reduce the FF of the ternary device based on Y6 material. In contrast, PM6 / N2200:PC 61 BM devices exhibit more efficient and balanced carrier transport, thus achieving higher FF and PCE values.

[0094] The solar cells of Example 1, Comparative Example 2, Example 2 and Comparative Example 3 were tested for current density-voltage performance. The results are as follows: Figure 6 As shown, it can be seen that based on PM6 / N2200:PC 61The photovoltaic performance of the BM system maintained good consistency on both rigid ITO and flexible PET substrates. Due to unbalanced charge transfer, significant recombination losses occur, and the free carrier population decreases dramatically. The open-circuit voltage and fill factor of the PM6 / N2200:Y6 device on the conductive PET substrate are significantly lower than those on the rigid ITO substrate.

[0095] As can be seen from the above examples, the present invention provides a flexible all-polymer solar cell with a high fill factor, the structure of which is as follows from bottom to top: flexible substrate, anode layer, hole transport layer, polymer donor layer, polymer acceptor layer, electron transport layer and cathode layer. The active layer of the present invention adopts a layer-by-layer structure, including a polymer donor layer and a polymer acceptor layer, and introduces a fullerene acceptor PC into the polymer acceptor N2200 material layer. 61 BM or small molecule receptor Y6 is used as the third component. By improving the active layer morphology of all-polymer solar cells, all-polymer solar cells based on PET flexible conductive substrates have achieved fill factors and charge transfer capabilities comparable to those of ITO rigid substrates. This can ensure that all-polymer solar cells exhibit good photoelectric conversion efficiency and long-term device stability on both rigid substrates ITO and flexible substrates PET.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A flexible all-polymer solar cell with a high fill factor, characterized in that: The structure of the flexible all-polymer solar cell with a high filling factor is, from bottom to top, a flexible substrate, an anode layer, a hole transport layer, a polymer donor layer, a polymer acceptor layer, an electron transport layer and a cathode layer.

2. The flexible all-polymer solar cell with a high fill factor as claimed in claim 1, characterized in that: The material of the flexible substrate is one or more of polyvinyl alcohol, polyester, polyimide and polyethylene naphthalate; The material of the anode layer is polyethylene terephthalate; The material of the hole transport layer is PEDOT:PSS; The thickness of the hole transport layer is 16-35 nm.

3. The flexible all-polymer solar cell with a high fill factor as claimed in claim 2, characterized in that: The material of the polymer donor layer is PM6; the thickness of the polymer donor layer is 57-65 nm; The material of the polymer receptor layer is a PCBM-based material or a Y6-based material; When the material of the polymer receptor layer is a PCBM-based material, the PCBM-based material comprises polymer N2200 and PCBM; the mass ratio of the polymer N2200 to PCBM is 6-10:1-3; When the material of the polymer receptor layer is a Y6-based material, the Y6-based material comprises polymer N2200 and Y6; the mass ratio of the polymer N2200 to Y6 is 6-10:1-3; The thickness of the polymer receptor layer is 55-65 nm.

4. The flexible all-polymer solar cell with a high fill factor as claimed in claim 3, characterized in that: The material of the electron transport layer is PDINO or LiF; the thickness of the electron transport layer is 8 to 15 nm; The material of the cathode layer is Al or Ag; the thickness of the cathode layer is 70-110 nm.

5. The method for preparing a flexible all-polymer solar cell with a high fill factor according to any one of claims 1 to 4, characterized in that: It includes the following steps: (1) forming an anode layer on one side of the flexible substrate; (2) Spin coating the PEDOT:PSS solution on the surface of the anode layer and annealing to obtain a hole transport layer; (3) Spin coating the PM6 solution on the surface of the hole transport layer to obtain a polymer donor layer; (4) spin coating a polymer receptor layer material solution on the surface of the polymer donor layer to obtain a polymer receptor layer; (5) coating an electron transport layer material solution on the surface of the polymer receptor layer to obtain an electron transport layer; (6) By evaporating the cathode layer on the surface of the electron transport layer, a flexible all-polymer solar cell with a high fill factor can be obtained.

6. The method for preparing a flexible all-polymer solar cell with a high fill factor according to claim 5, wherein: In step (2), the volume ratio of PEDOT:PSS to water in the PEDOT:PSS solution is 1-2:1-2; The spin coating in step (2) is performed at a speed of 3000 to 5000 rpm for 20 to 40 seconds. The annealing treatment in step (2) is performed at a temperature of 80 to 120° C. for 5 to 15 minutes.

7. The method for preparing a flexible all-polymer solar cell with a high fill factor according to claim 6, wherein: The concentration of the PM6 solution in step (3) is 5 to 15 mg / mL; The spin coating in step (3) is performed at a rotation speed of 1000 to 3000 rpm and for a time of 20 to 40 seconds.

8. The method for preparing a flexible all-polymer solar cell with a high fill factor according to claim 7, wherein: The concentration of the polymer receptor layer material solution in step (4) is 8 to 10 mg / mL; The spin coating in step (4) is performed at a rotation speed of 1000 to 3000 rpm and for a time of 20 to 40 seconds.

9. The method for preparing a flexible all-polymer solar cell with a high fill factor according to claim 8, wherein: The concentration of the electron transport layer material solution in step (5) is 1 to 3 mg / mL; The coating method in step (5) is spin coating or evaporation; When the coating method is spin coating, the spin coating speed is 1000-3000 rpm and the time is 30-50 s; When the coating method is evaporation, the vacuum degree of the evaporation is ≤0.0004Pa, and the deposition rate is 10. The method for preparing a flexible all-polymer solar cell with a high fill factor according to claim 9, wherein: The vacuum degree of the evaporation in step (6) is ≤0.0003 Pa, the turntable speed is 4-6 r / min, and the growth rate is 2-4 nm / s.

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