An organic solar cell and an organic-inorganic heterojunction control method thereof

Abstract

The present invention discloses an organic solar cell and a method for regulating its organic-inorganic heterointerface. The present invention passivates metal oxide nanoparticles through conjugated molecular monolayers (SAMs), thereby improving the chemical, electrical and electronic properties of the organic-inorganic heterointerface and realizing a highly efficient and stable organic solar cell. The interface modification method is achieved by blending SAMs with a dispersion of zinc oxide nanoparticles and annealing the spin-coated film at low temperature. By using zinc oxide nanoparticles passivated by SAMs, not only is the current highest photoelectric conversion efficiency of organic solar cells using metal oxides as electron transport layers achieved, but the light stability of the cell is also improved. In addition, the interface material also exhibits the most ideal thickness-insensitive characteristics (up to 300nm).

Description

Technical Field

[0001] The present invention belongs to the field of energy materials, and in particular relates to an organic solar cell and an organic-inorganic heterogeneous interface control method thereof. Background Art

[0002] Charge extraction at organic-inorganic heterointerfaces severely impacts the overall performance of optoelectronic devices, particularly organic solar cells (ORCs). Despite rapid development in recent years, ORCs have achieved photoelectric conversion efficiencies of nearly 19% (Li C, Zhou J, Song J, et al. Nat. Energy. 2021; 6:605-613. doi:10.1038 / s41560-021-00820-x; Meng H, Liao C, Deng M, Xu X, Yu L, Peng Q. Angew. Chem. Int. Ed. 2021. doi:10.1002 / anie.202110550; Cui Y, Xu Y, Yao H, et al. Adv. Mater. 2021: e2102420. doi:10.1002 / adma.202102420). However, achieving industrialization still requires the efforts of researchers. Metal oxide nanoparticles, as a low-cost electron transport material that can be processed on a large scale under low-temperature conditions, are conducive to achieving a balance between efficiency, stability and cost in organic solar cells.

[0003] However, metal oxide nanoparticles, such as zinc oxide (ZnO) nanoparticles, possess numerous surface and interface defect states, which are mismatched with the energy levels of high-performance non-fullerene acceptors, leading to severe carrier recombination at the interface. Furthermore, ZnO nanoparticles tend to aggregate in solution, compromising their processability and conductivity. Furthermore, the photocatalytic activity of ZnO nanoparticles can cause degradation of the organic active layer. These issues severely restrict charge transport across the organic-inorganic heterointerface formed between the organic active layer and the metal oxide nanoparticles, thereby impacting the efficiency and stability of organic solar cells. Therefore, developing metal oxide nanoparticles with superior properties and manipulating the organic-inorganic heterointerface are crucial for achieving low-cost, high-performance organic solar cells. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an organic solar cell and a method for controlling an organic-inorganic heterojunction interface thereof.

[0005] The specific technical solutions adopted in the present invention are as follows:

[0006] In a first aspect, the present invention provides a method for regulating an organic-inorganic heterogeneous interface, which comprises: mixing an organic conjugated molecule and metal oxide nanoparticles in an organic solvent, stirring the mixture sufficiently to passivate the metal oxide nanoparticles, and obtaining a dispersion; and subjecting the dispersion to low-temperature annealing of a thin film obtained by spin coating the dispersion to achieve regulation of the organic-inorganic heterogeneous interface.

[0007] The organic conjugated molecule is one of 4-methoxybenzoic acid, 4-hexyloxybenzoic acid, or 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid, and their structural formulas are as follows:

[0008]

[0009] Preferably, the mass ratio of the organic conjugated molecules to the metal oxide nanoparticles is 1:(5-20), the passivation reaction time is 6-24h; the concentration of the metal oxide nanoparticles in the dispersion is 1-100mg mL -1 .

[0010] Preferably, the organic solvent is an alcohol solvent, a halogen-containing solvent or a non-halogen solvent.

[0011] Preferably, during the low-temperature annealing process, the temperature is 20-200° C. and the annealing time is 1-100 min.

[0012] Preferably, the metal oxide nanoparticles are zinc oxide nanoparticles, and the preparation method is as follows:

[0013] Under dry reaction conditions, zinc acetate dihydrate is stirred and dissolved in methanol, and after heating, a methanol solution of potassium hydroxide is added to obtain a reaction solution; the reaction solution is heated under reflux reaction, and then allowed to stand and cool until a solid is completely precipitated, and the precipitated solid product is washed with methanol to obtain zinc oxide nanoparticles.

[0014] Furthermore, in the preparation method, 9-9.5 mL of methanol is added to every 1 mmol of zinc acetate dihydrate, and 2-2.5 mL of methanol is added to every 1 mmol of potassium hydroxide; the heating temperature when preparing the reaction solution is 60-80°C; the temperature of the heating reflux reaction is 60-80°C, and the reaction time is 3 hours.

[0015] In a second aspect, the present invention provides an organic solar cell based on metal oxide, comprising a substrate, a transparent electrode layer, a hole transport layer, an active layer, an electron transport layer and a metal electrode layer arranged in layers from bottom to top; the electron transport layer is prepared by the organic-inorganic heterogeneous interface regulation method as described in any one of the first aspects.

[0016] Preferably, the active layer is a blended film of an organic electron donor material and an organic electron acceptor material; the organic electron donor material is PM6; the organic electron acceptor material is one of Y6 or BO-4Cl or a combination of BO-4Cl and Y6-1O.

[0017] Preferably, the substrate material is one of glass, quartz, flexible polyethylene terephthalate (PET) or flexible polyethylene naphthalate (PEN).

[0018] Preferably, the thickness of the electron transport layer is 5-300 nm.

[0019] The preparation process of the organic solar cell provided by the present invention is specifically as follows:

[0020] 1) Preparation of substrate + transparent electrode layer: Transparent conductive glass with indium tin oxide (ITO) strips etched on the surface (cathode) was cleaned with a detergent, deionized water, acetone, and isopropyl alcohol by ultrasonic oscillation for 30 minutes, dried with a nitrogen stream, and then treated with ultraviolet and ozone plasma for 10 minutes.

[0021] 2) Preparation of hole transport layer: PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at a rotation speed of 4500 rpm, annealed at 170° C. for 20 minutes, and then transferred to a glove box.

[0022] 3) Preparation of active layer: When the active layer solution is PM6 / Y6 (16.5 mg mL -1 When the active layer solution was PM6 / BO-4Cl (16.5 mg mL -1 When the active layer solution was PM6 / BO-4Cl / Y6-1O (16.5 mg mL -1 The active layer solution was spin-coated on the hole transport layer at a speed of 3000 rpm and annealed at 90° C. for 7 minutes.

[0023] 4) Preparation of electron transport layer: Spin-coat 5 mg mL on the active layer at 3000 rpm. -1 The SAM (self-assemble monolayers) passivated ZnO nanoparticles were added to an ethanol dispersion and annealed at 90 °C for 3 min.

[0024] Here, SAM refers to an organic conjugated molecule selected from 4-methoxybenzoic acid, 4-(hexyloxy)benzoic acid, or 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid. The specific method is consistent with the above-mentioned organic-inorganic heterogeneous interface control method.

[0025] 5) Preparation of metal electrode layer: -4 Under a background pressure of Pa, a 100nm thick Ag electrode was deposited by thermal evaporation to finally obtain an organic solar cell with the above six-layer structure.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention optimizes the chemical, electrical, and electronic properties of the organic-inorganic heterojunction interface by grafting three conjugated molecular monolayers onto metal oxide nanoparticles, thereby realizing a highly efficient and stable organic solar cell. The solvent-philic 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid not only allows the zinc oxide nanoparticles to be uniformly and stably dispersed in the solution, but also improves the interfacial properties of the zinc oxide nanoparticles, resulting in optimal energy levels and electrical conductivity. The zinc oxide nanoparticles passivated with 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid are applied to organic solar cells, achieving the highest current photoelectric conversion efficiency for organic solar cells using metal oxides as electron transport layers, while also improving the cells' photostability. Furthermore, the interface material exhibits an ideal thickness-insensitive characteristic (up to 300 nm). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the organic-inorganic heterogeneous interface control method of the present invention;

[0029] Figure 2 Schematic diagram of the structure of the organic solar cell in the present invention;

[0030] Figure 3 The current-voltage curves of the organic solar cells obtained in Example 3 and Comparative Example 1 are shown;

[0031] Figure 4 The current-voltage curves of the organic solar cells obtained in Example 4, Example 5 and Comparative Example 3 are shown;

[0032] Figure 5 The efficiency-electron transport layer thickness curves of organic solar cells obtained from Example 3, Comparative Example 2, and reported electron transport materials;

[0033] Figure 6 1 is the UV stability curve of the organic solar cells obtained in Example 4 and Comparative Example 3;

[0034] The reference numerals in the figure are: substrate 1, transparent electrode layer 2, hole transport layer 3, active layer 4, electron transport layer 5 and metal electrode layer 6. DETAILED DESCRIPTION

[0035] The present invention will be further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflict. The reagents used in each embodiment can be commercially available products without special restrictions.

[0036] The present invention uses three benzoic acid derivatives (i.e., organic conjugated molecules 4-methoxybenzoic acid, 4-(hexyloxy)benzoic acid, or 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid) to passivate metal oxide nanoparticles to achieve organic-inorganic heterogeneous interface regulation. The specific process is as follows Figure 1 As shown, organic conjugated molecules and metal oxide nanoparticles are mixed in an organic solvent and stirred thoroughly. The organic conjugated molecules are then used to passivate the metal oxide nanoparticles to produce a dispersion. This dispersion is then spin-coated during the organic solar cell fabrication process, and the resulting film is annealed at low temperature to form an electron transport layer. The introduction of this electron transport layer into organic solar cells achieves high efficiency and improved photostability. Furthermore, the electron transport layer exhibits optimal thickness insensitivity (up to 300 nm).

[0037] The organic conjugated molecule is one of 4-methoxybenzoic acid, 4-(hexyloxy)benzoic acid or 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid, and their structural formulas are as follows:

[0038]

[0039] Example 1

[0040] In this embodiment, zinc oxide nanoparticles were prepared, and the preparation method is as follows:

[0041] In a dry reaction flask, zinc acetate dihydrate (2.95 g) was stirred and dissolved in methanol (125 mL). After heating to 60°C, a solution of potassium hydroxide (1.48 g) in methanol (65 mL) was added to obtain a reaction solution. After heating the reaction solution under reflux at 60°C for 3 hours, it was allowed to cool for 5 hours to allow the zinc oxide nanoparticles to naturally settle. The precipitated solid was then washed twice with methanol to obtain zinc oxide nanoparticles (metal oxide nanoparticles), which were recorded as D-ZnO NPs.

[0042] Example 2

[0043] In this example, the zinc oxide nanoparticles obtained in Example 1 were used to prepare an ethanol dispersion of zinc oxide nanoparticles after SAM passivation, as follows:

[0044] In a dry reaction flask, benzoic acid derivatives 4-methoxybenzoic acid, 4-(hexyloxy)benzoic acid, and 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid were added to 5 mg mL of -1 The zinc oxide nanoparticles were fully passivated by using benzoic acid derivatives in an ethanol dispersion of zinc oxide nanoparticles, and three dispersions were obtained, which were respectively marked as DS1-ZnO NPs, DS2-ZnO NPs and DS3-ZnO NPs.

[0045] Example 3

[0046] In this example, three organic solar cells were prepared using the products DS1-ZnO NPs, DS2-ZnO NPs, and DS3-ZnO NPs obtained in Example 2 based on the active layer solution PM6 / Y6. The specific preparation processes are as follows:

[0047] The transparent conductive glass with indium tin oxide (ITO) strips etched on the surface was cleaned with detergent, deionized water, acetone, and isopropyl alcohol in sequence by ultrasonic oscillation for 30 minutes, dried with nitrogen flow, and then treated with ultraviolet and ozone plasma for 10 minutes. A PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at 4500 rpm and annealed at 170°C for 20 minutes before being transferred to a glove box. The active layer solution PM6 / Y6 (16.5 mg mL -1Chloroform solution, weight ratio 1:1.2, 0.5% CN) was spin-coated at 3000 rpm and annealed at 90 °C for 7 min.

[0048] Then, 5 mg mL was spin-coated on the active layer at a speed of 3000 rpm. -1 The ethanol dispersion of zinc oxide nanoparticles after S1 passivation (DS1-ZnO NPs) was prepared and annealed at 90 °C for 3 min; or 5 mg mL was spin-coated on the active layer at a speed of 3000 rpm. -1 The ethanol dispersion of S2-passivated zinc oxide nanoparticles (DS2-ZnO NPs) was prepared and annealed at 90 °C for 3 min; or 5 mg mL was spin-coated on the active layer at a speed of 3000 rpm. -1 The ethanol dispersion of zinc oxide nanoparticles after S3 passivation (DS3-ZnO NPs) was prepared and annealed at 90°C for 3 minutes. The electron transport layer of different thicknesses can be formed by adjusting the rotation speed, concentration or number of layers.

[0049] Finally, at 2.0×10 -4 Ag electrodes with a thickness of 100 nm were deposited by thermal evaporation under a background pressure of Pa. The three organic solar cells prepared were denoted as S1-ZnO NPs, S2-ZnO NPs and S3-ZnO NPs, and their structures were as follows Figure 2 As shown, it includes a substrate 1, a transparent electrode layer 2, a hole transport layer 3, an active layer 4, an electron transport layer 5, and a metal electrode layer 6 arranged in layers from bottom to top. The current-voltage curve test results of the device are shown in FIG. Figure 3 The device efficiency changes with the thickness of the electron transport layer. Figure 5 .

[0050] Comparative Example 1

[0051] In this comparative example, an organic solar cell was prepared using the same method as in Example 1, with the only difference being that the ethanol dispersion of zinc oxide nanoparticles was not subjected to a SAM passivation reaction during the preparation of the electron transport layer. The specific preparation process is as follows:

[0052] The transparent conductive glass with strips of indium tin oxide (ITO) etched on the surface (cathode) was cleaned with detergent, deionized water, acetone, and isopropyl alcohol in sequence by ultrasonic oscillation for 30 minutes, dried with nitrogen flow, and then treated with ultraviolet and ozone plasma for 10 minutes. PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at a speed of 4500 rpm and annealed at 170°C for 20 minutes before being transferred to a glove box. The active layer solution was PM6 / Y6 (16.5 mg mL -1Chloroform solution, weight ratio 1:1.2, 0.5% CN) was spin-coated at 3000 rpm and annealed at 90 °C for 7 min; 5 mg mL was spin-coated on the active layer at 3000 rpm. -1 The ethanol dispersion of unpassivated ZnO nanoparticles (D-ZnO NPs) was prepared and annealed at 90 °C for 3 min. -4 Ag electrodes with a thickness of 100 nm were deposited by thermal evaporation under a background pressure of Pa to obtain organic solar cells, which were denoted as ZnO NPs.

[0053] The current-voltage curve test results of the device are as follows: Figure 3 .

[0054] Comparative Example 2

[0055] In this comparative example, an organic solar cell was prepared using the same method as in Example 1, with the only difference being that the ethanol dispersion of zinc oxide nanoparticles was replaced with a methanol solution of PFN-Br during the preparation of the electron transport layer. This was done to compare the sensitivity of different electron transport layer thicknesses in organic solar cell devices. The preparation process is as follows:

[0056] The transparent conductive glass with strips of indium tin oxide (ITO) etched on the surface (cathode) was cleaned with detergent, deionized water, acetone, and isopropyl alcohol in sequence by ultrasonic oscillation for 30 minutes, dried with nitrogen flow, and then treated with ultraviolet and ozone plasma for 10 minutes. PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at a speed of 4500 rpm and annealed at 170°C for 20 minutes before being transferred to a glove box. The active layer solution was PM6 / Y6 (16.5 mg mL -1 Chloroform solution (weight ratio 1:1.2, 0.5% CN) was spin-coated at 3000 rpm and annealed at 90 ° C for 7 min; PFN-Br methanol solution was then spin-coated on the active layer, where the speed and concentration could be adjusted to form an electron transport layer of different thicknesses. Finally, at 2.0×10 -4 An organic solar cell was obtained by thermal evaporation deposition of a 100 nm thick Ag electrode under a background pressure of 1.5 Å Pa, which was labeled as PFN-Br.

[0057] The device efficiency changes with thickness as shown in the following results: Figure 5 .

[0058] Example 4

[0059] In this example, an organic solar cell was prepared using the product S3-ZnO NPs obtained in Example 2 based on the active layer solution PM6 / BO-4Cl. The preparation process is as follows:

[0060] The transparent conductive glass with strips of indium tin oxide (ITO) etched on the surface (cathode) was cleaned with detergent, deionized water, acetone, and isopropyl alcohol in sequence by ultrasonic oscillation for 30 minutes, dried with nitrogen flow, and then treated with ultraviolet and ozone plasma for 10 minutes. A PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at 4500 rpm and annealed at 170°C for 20 minutes before being transferred to a glove box. The active layer solution was PM6 / BO-4Cl (16.5 mg mL -1 Chloroform solution, weight ratio 1:1.2, 0.35% DIO) was spin-coated at 3000 rpm and annealed at 90 °C for 7 min; 5 mg mL was spin-coated on the active layer at 3000 rpm. -1 The ethanol dispersion of S3 passivated ZnO nanoparticles (DS3-ZnO NPs) was prepared and annealed at 90 °C for 3 min. -4 Ag electrodes with a thickness of 100 nm were deposited by thermal evaporation under a background pressure of Pa to obtain organic solar cells, which were denoted as S3-ZnO NPs.

[0061] The current-voltage curve test results are as follows: Figure 4 The test results of the photoelectric energy conversion efficiency changing with the UV irradiation time are as follows: Figure 6 .

[0062] Comparative Example 3

[0063] In this comparative example, an organic solar cell was prepared using the same method as in Example 4, with the only difference being that the ethanol dispersion of zinc oxide nanoparticles was not subjected to a SAM passivation reaction during the preparation of the electron transport layer. The specific preparation process is as follows:

[0064] The transparent conductive glass with strips of indium tin oxide (ITO) etched on the surface (cathode) was cleaned with detergent, deionized water, acetone, and isopropyl alcohol in sequence by ultrasonic oscillation for 30 minutes, dried with nitrogen flow, and then treated with ultraviolet and ozone plasma for 10 minutes. A PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at 4500 rpm and annealed at 170°C for 20 minutes before being transferred to a glove box. The active layer solution was PM6 / BO-4Cl (16.5 mg mL -1 Chloroform solution, weight ratio 1:1.2, 0.35% DIO) was spin-coated at 3000 rpm and annealed at 90 °C for 7 min; 5 mg mL was spin-coated on the active layer at 3000 rpm. -1 The ethanol dispersion of unpassivated ZnO nanoparticles (D-ZnO NPs) was prepared and annealed at 90 °C for 3 min. -4Ag electrodes with a thickness of 100 nm were deposited by thermal evaporation under a background pressure of Pa to obtain organic solar cells, which were denoted as ZnO NPs.

[0065] The test results of its photoelectric energy conversion efficiency changing with UV irradiation time are as follows: Figure 6 .

[0066] Example 5

[0067] In this example, an organic solar cell was prepared using the product S3-ZnO NPs obtained in Example 2 based on the active layer solution PM6 / BO-4Cl / Y6-1O. The preparation process is as follows:

[0068] The transparent conductive glass with strips of indium tin oxide (ITO) etched on the surface (cathode) was cleaned with detergent, deionized water, acetone, and isopropyl alcohol in sequence by ultrasonic oscillation for 30 minutes, dried with nitrogen flow, and then treated with ultraviolet and ozone plasma for 10 minutes. A PEDOT:PSS (Baytron P AI4083) solution was spin-coated on the ITO surface at 4500 rpm and annealed at 170°C for 20 minutes before being transferred to a glove box. The active layer solution was PM6 / BO-4Cl / Y6-1O (16.5 mg mL -1 Chloroform solution (weight ratio 1:0.9:0.3, 0.25% DIO) was spin-coated at 3000 rpm and annealed at 90 °C for 7 min; 5 mg mL was spin-coated on the active layer at 3000 rpm. -1 The ethanol dispersion of S3 passivated ZnO nanoparticles (DS3-ZnO NPs) was prepared and annealed at 90 °C for 3 min. -4 An organic solar cell was obtained by thermal evaporation deposition of a 100 nm thick Ag electrode under a background pressure of 1.5 Pa, which was denoted as PM6:BO-4Cl:Y6-1O.

[0069] The current-voltage curve test results are as follows: Figure 4 .

[0070] At a light intensity of 100 mW cm -2 The current-voltage curves of Examples 3-5 and Comparative Examples 1-2 were tested under irradiation with AM 1.5G simulated sunlight.

[0071] The test results of PM6 / Y6 system are as follows Figure 3 The open circuit voltage of the device based on the unpassivated zinc oxide nanoparticles (denoted as ZnO NPs) in Comparative Example 1 is 0.81 V, and the short circuit current density is 26.06 mA cm -2, the fill factor is 0.62, and the photoelectric energy conversion efficiency is 13.20%. The device based on S1-passivated zinc oxide nanoparticles in Example 3 (denoted as S1-ZnO NPs) has an open circuit voltage of 0.50 V and a short circuit current density of 24.84 mA cm -2 , the fill factor is 0.51, and the photoelectric energy conversion efficiency is 6.31%. The device based on S2-passivated zinc oxide nanoparticles in Example 3 (denoted as S2-ZnO NPs) has an open circuit voltage of 0.85 V and a short circuit current density of 26.80 mA / cm 2 , the fill factor is 0.74, and the photoelectric energy conversion efficiency is 16.87%; the device based on S3 passivated zinc oxide nanoparticles in Example 3 (denoted as S3-ZnO NPs) has an open circuit voltage of 0.85 V and a short circuit current density of 27.09 mA / cm 2 , the filling factor is 0.76, and the photoelectric energy conversion efficiency is 17.57%.

[0072] The test results of PM6 / BO-4Cl system and PM6 / BO-4Cl / Y6-1O are as follows Figure 4 In the PM6 / BO-4Cl system, the device based on S3-passivated zinc oxide nanoparticles in Example 4 (denoted as PM6:BO-4Cl) has an open circuit voltage of 0.86 V and a short circuit current density of 26.98 mA cm -2 , the fill factor is 0.78, and the photoelectric energy conversion efficiency is 18.02%. In the PM6 / BO-4Cl / Y6-1O system, the device based on S3-passivated zinc oxide nanoparticles in Example 5 (denoted as PM6:BO-4Cl:Y6-1O) has an open circuit voltage of 0.86 V and a short circuit current density of 27.34 mA cm -2 , the filling factor is 0.78, and the photoelectric energy conversion efficiency is 18.14%.

[0073] At the same time, when the light intensity is 100 mW cm -2Example 3, Comparative Example 2 and reported electron transport materials (Bai Y, Zhao C, Chen X, et al. J. Mater. Chem. A. 2019; 7(26): 15887-15894. doi: 10.1039 / c9ta05789g; Liu M, Fan P, Hu Q, Russell TP, Liu Y. Angew. Chem. Int. Ed. 2020; 59(41): 18131-18135. doi: 10.1002 / anie.202004432; Tang H, Liu Z, Tang Y ... al.Giant.2021;6:100053.doi:10.1016 / j.giant.2021.100053;YaoJ,Qiu B,Zhang ZG,et al.Nat.Commun.2020;11(1):2726.doi:10.1038 / s41467-020-16509-w) The device efficiency curve changes with the thickness of the electron transport layer. The results are as follows Figure 5 As shown. Under the PM6 / Y6 system, when the thickness of the electron transport layer PFN-Br of the device based on PFN-Br in Comparative Example 2 (denoted as PFN-Br) is 10nm, the photoelectric conversion efficiency of the device drops to 8.34% of the maximum efficiency. The device based on S3 passivated zinc oxide nanoparticles in Example 3 (denoted as S3-ZnONPs) shows excellent thickness insensitivity. When the thickness of the electron transport layer reaches 200nm, the photoelectric energy conversion efficiency of the device is 80.57% of the maximum efficiency; when the thickness of the electron transport layer reaches 300nm, the photoelectric energy conversion efficiency of the device remains at 70.06% of the maximum efficiency.

[0074] In addition, at a light intensity of 100 mW cm -2 Under AM 1.5G simulated sunlight, the photoelectric conversion efficiency of the devices of Example 4 and Comparative Example 3 was tested as a function of 365nm UV lamp irradiation time. The results are as follows: Figure 6 In the PM6 / BO-4Cl system, the photoelectric energy conversion efficiency of the device based on unpassivated zinc oxide nanoparticles (denoted as ZnO NPs) in Comparative Example 3 dropped to 24.28% of the initial efficiency after 16 hours of UV irradiation. However, the photoelectric energy conversion efficiency of the device based on S3-passivated zinc oxide nanoparticles (denoted as S3-ZnO NPs) in Example 4 remained at 81.73% of the initial efficiency after 16 hours of UV irradiation.

[0075] This demonstrates that zinc oxide nanoparticles passivated by conjugated monolayers can improve the chemical, electrical, and electronic properties of the organic-inorganic heterojunction interface in organic solar cells, thereby achieving the highest current photoelectric conversion efficiency for organic solar cells using metal oxides as electron transport layers and enhancing the cells' photostability. Furthermore, this interface material exhibits optimal thickness insensitivity (up to 300 nm).

[0076] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A method for regulating an organic-inorganic heterogeneous interface, characterized in that: Specifically, the organic conjugated molecules and metal oxide nanoparticles are mixed in an organic solvent, and the mixture is stirred thoroughly to passivate the metal oxide nanoparticles to obtain a dispersion; a thin film obtained by spin coating the dispersion is subjected to low-temperature annealing to achieve regulation of the organic-inorganic heterogeneous interface; The organic conjugated molecule is one of 4-methoxybenzoic acid, 4-hexyloxybenzoic acid or 4-(2-(2-methoxyethoxy)ethoxy)benzoic acid, and their structural formulas are as follows: The metal oxide nanoparticles are zinc oxide nanoparticles.

2. The method for controlling the organic-inorganic heterogeneous interface according to claim 1, characterized in that: The mass ratio of the organic conjugated molecules to the metal oxide nanoparticles is 1:(5-20), the passivation reaction time is 6-24h; the concentration of the metal oxide nanoparticles in the dispersion is 1-100mg mL -1 .

3. The method for controlling the organic-inorganic heterogeneous interface according to claim 1, wherein: The organic solvent is one of an alcohol solvent, a halogen-containing solvent or a non-halogen solvent.

4. The method for controlling the organic-inorganic heterogeneous interface according to claim 1, wherein: During the low-temperature annealing process, the temperature is 20-200° C. and the annealing time is 1-100 minutes.

5. The method for controlling the organic-inorganic heterogeneous interface according to claim 1, wherein: The preparation method of the zinc oxide nanoparticles is as follows: Under dry reaction conditions, zinc acetate dihydrate is stirred and dissolved in methanol, and after heating, a methanol solution of potassium hydroxide is added to obtain a reaction solution; the reaction solution is heated under reflux reaction, and then allowed to stand and cool until a solid is completely precipitated, and the precipitated solid product is washed with methanol to obtain zinc oxide nanoparticles.

6. The method for controlling the organic-inorganic heterogeneous interface according to claim 5, characterized in that: In the preparation method, 9-9.5 mL of methanol is added to every 1 mmol of zinc acetate dihydrate, and 2-2.5 mL of methanol is added to every 1 mmol of potassium hydroxide; the heating temperature during preparation of the reaction solution is 60-80° C.; the temperature of the heating reflux reaction is 60-80° C., and the reaction time is 3 hours.

7. An organic solar cell, characterized in that: The invention comprises a substrate (1), a transparent electrode layer (2), a hole transport layer (3), an active layer (4), an electron transport layer (5) and a metal electrode layer (6) which are arranged in layers from bottom to top; the electron transport layer (5) is prepared by the organic-inorganic heterogeneous interface control method according to any one of claims 1 to 6.

8. The organic solar cell according to claim 7, characterized in that The active layer (4) is a blended film of an organic electron donor material and an organic electron acceptor material; the organic electron donor material is PM6; and the organic electron acceptor material is one of Y6, BO-4Cl, or a combination of BO-4Cl and Y6-1O.

9. The organic solar cell according to claim 7, characterized in that The substrate (1) is made of glass, quartz, flexible polyethylene terephthalate or flexible polyethylene naphthalate.

10. The organic solar cell according to claim 7, characterized in that The thickness of the electron transport layer (5) is 5-300 nm.

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