Electron transport layer, semitransparent organic solar cell prepared by full solution and preparation method of semitransparent organic solar cell

Abstract

The invention discloses an electron transport layer, a semitransparent organic solar cell prepared by a full solution and a preparation method of the semitransparent organic solar cell. The electron transport layer is selected from a blended membrane formed by materials including metal oxide nanoparticles and polymers. The full-solution prepared semitransparent organic solar cell sequentially comprises an anode, a hole transport layer, an organic active layer, the electron transport layer and a cathode from bottom to top. The electron transport layer can be used for a conventional forward device (such as an evaporation electrode) and plays a role in improving the efficiency of the device, and more importantly, the blended electron transport layer of the metal oxide nanoparticles and the polymer has the advantages of being insensitive in thickness and capable of tolerating solution treatment of a top electrode.

Description

Technical Field

[0001] The present invention belongs to the field of organic solar cells, and particularly relates to a fully solution-processed semi-transparent organic solar cell. Specifically, it relates to an electron transport layer, a fully solution-processed semi-transparent organic solar cell and a preparation method thereof. Background Art

[0002] Organic solar cells have advantages such as low cost, solution processability, flexibility and semi-transparency, and have important application prospects. Due to the high molar extinction coefficient of organic materials, chemical structure diversity and precise bandgap regulation, organic solar cells can achieve semi-transparency or even full transparency, and have broad application potential in building integration and automotive glass, etc. At the same time, the preparation of devices by full solution processing is a prerequisite for the large-scale application of organic solar cells, and is also a major feature and advantage of organic solar cells. Therefore, developing a semi-transparent organic photovoltaic preparation process by full solution processing has important value and significance. Organic solar cells usually adopt a normal structure, which, from bottom to top, successively consists of a transparent electrode, a hole transport layer, an active layer, an electron transport layer and a cathode. At present, for the preparation of most laboratory organic photovoltaic devices, except for the transparent electrode and the back electrode which are prepared by evaporation, the other layers are all solution processed. Since the transparent electrode can be commercially produced, the solution-processed top electrode is the key to realizing a fully solution-processed organic solar cell.

[0003] At present, the efficiency of fully solution-processed organic photovoltaic devices is generally low. The main reason is that during the coating process of solution-processed back electrode materials such as silver nanowires or metal nanoparticles, the solvent will erode the underlying interfacial layer and the active layer, and the silver nanowires or metal particles will pierce through the interfacial layer and the active layer. Thus, it can be seen that the interfacial layer material in contact with the top electrode plays a key role. For normal devices, the electron transport layer plays a role in connecting the solution-processed top electrode and the active layer. The currently commonly used electron transport layer materials generally have an optimal thickness of less than 10 nm and are not dense enough, making it difficult to withstand the solvent erosion and possible piercing during the process of solution-processing the top electrode, resulting in poor performance of the final photovoltaic device. Therefore, developing an interfacial layer material that can withstand the solution-processed top electrode is the key to fully solution-processed organic solar cells. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides an electron transport layer, an electron transport layer for a fully solution-processed semi-transparent organic solar cell and a preparation method thereof. The present invention can obtain an electron transport layer in a low-cost manner and can withstand the solution-processed top electrode, and then methods such as spin coating or blade coating can be adopted to directly solution-process a silver nanowire top electrode, so as to obtain a fully solution-processed semi-transparent organic solar cell.

[0005] One object of the present invention is to provide an electron transport layer, and the electron transport layer is a blend film of metal oxide nanoparticles and a polymer.

[0006] In the present invention, metal oxide nanoparticles are used instead of metal oxides prepared by the sol-gel method (such as sol-gel ZnO). After spin-coating or blade-coating with metal oxide nanoparticles (such as nano-zinc oxide particles), only a relatively low annealing temperature (90 °C to 120 °C is acceptable) is required for 5 to 10 minutes, while metal oxides prepared by the sol-gel method (such as sol-gel ZnO) require annealing at a high temperature of about 200 °C for 1 hour. Therefore, metal oxides prepared by the sol-gel method (such as sol-gel ZnO) can only be used as the electron transport layer of reverse devices, while metal oxide nanoparticles (such as nano-zinc oxide particles) can be used as the electron transport layer of forward devices.

[0007] In the present invention, the electron transport layer can not only be used in conventional devices (such as vapor-deposited electrodes), playing a positive role in improving the device efficiency. More importantly, the electron transport layer of the present invention can also be directly in contact with the cathode solution. The blend electron transport layer of metal oxide nanoparticles and a polymer in the present invention has the advantages of being insensitive to thickness and being tolerant to solution-processed top electrodes; preferably, the cathode solution is a solution-processed silver nanowire; more preferably, the cathode solution is a silver nanowire solution, preferably an aqueous silver nanowire solution and / or an alcoholic silver nanowire solution, preferably, the alcohol is selected from at least one of ethanol and isopropanol; more preferably, the concentration of silver nanowires is 0.1 to 1 wt%, preferably 0.3 to 0.5 wt%, for example, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1 wt%.

[0008] Among them, the silver nanowire solution electrode can realize a semi-transparent organic solar cell, and a fully solution-processed semi-transparent cell can be realized by regulating the formulations of the interfacial layer and the solution-processed top electrode.

[0009] In a preferred embodiment, the electron transport layer is resistant to the solution cathode, that is, an electron transport layer that is resistant to the solution cathode.

[0010] Among them, a solution cathode is prepared by a spin-coating or blade-coating process above the electron transport layer.

[0011] In a further preferred embodiment, the rotation speed of the spin-coating is 1000 to 4000 rpm, preferably 2000 to 3000 rpm, for example, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm or 4000 rpm.

[0012] In a preferred embodiment, the metal oxide nanoparticles are selected from at least one of zinc oxide nanoparticles and tin dioxide nanoparticles.

[0013] In a further preferred embodiment, the average particle size of the metal oxide nanoparticles is 10 - 100 nm, preferably 10 - 50 nm.

[0014] In a preferred embodiment, the polymer is selected from at least one of PVP (polyvinylpyrrolidone), PVB (polyvinyl butyral), PEO (polyethylene oxide), PEI (polyethyleneimine), P4VP (poly(4-vinylpyridine) multiarm star polymer), and PAA (polyacrylic acid), and more preferably from PVP, PVB, PEO, and PAA.

[0015] Among them, the inventors found through a large number of experimental studies that the electron transport layer including metal oxide nanoparticles and polymers has the advantages of being insensitive to thickness and being able to withstand direct solution processing of the top electrode (solution cathode). The inventors found through a large number of experimental studies that among the polymers, PVB has the best effect, with the highest PCE and more balanced parameters.

[0016] In a further preferred embodiment, the molecular weight of the polymer is 10,000 - 50,000, preferably 30,000 - 50,000.

[0017] In a preferred embodiment, in the electron transport layer, the weight ratio of the metal oxide nanoparticles to the polymer is 100:(10 - 50), preferably 100:(10 - 30), such as 100:10, 100:20, 100:30, 100:40, or 100:50.

[0018] In a preferred embodiment, the thickness of the electron transport layer is 10 - 200 nm, preferably 30 - 60 nm, such as 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, or 200 nm.

[0019] In a preferred embodiment, the electron transport layer is used for a forward device.

[0020] A second object of the present invention is to provide a method for preparing the electron transport layer described in the first object of the present invention, including: (1) dispersing (preferably dissolving) a polymer in an organic solvent to obtain a polymer dispersion, and dispersing a metal oxide in an organic solvent to obtain a metal oxide dispersion; (2) mixing the polymer dispersion with the metal oxide dispersion to obtain an electron transport layer mixture dispersion; (3) subjecting the electron transport layer mixture dispersion to spin coating or blade coating treatment to form an electron transport layer.

[0021] Preferably, the electron transport layer can be directly in contact with the cathode solution. For example, the cathode solution is spin-coated or blade-coated on the electron transport layer to form a solution-processed top electrode.

[0022] The present invention mixes a metal oxide with a polymer to prepare and form an electron transport layer, which can improve the thickness insensitivity of the electron transport layer and overcome the drawback that the currently commonly used electron transport interface layer materials cannot withstand the solution-processed top electrode.

[0023] In a preferred embodiment, the organic solvent in step (1) is selected from alcohol solvents, preferably at least one of methanol, ethanol, butanol, and isopropanol.

[0024] In a further preferred embodiment, in the electron transport layer mixture dispersion, the concentration of the metal oxide is 5 - 30 mg / ml, preferably 10 - 20 mg / ml, such as 5 mg / ml, 10 mg / ml, 15 mg / ml, 20 mg / ml, 25 mg / ml, or 30 mg / ml.

[0025] In a still further preferred embodiment, in the electron transport layer mixture dispersion, the concentration of the polymer is 0.5 - 5 mg / ml, preferably 1 - 3 mg / ml, such as 0.5 mg / ml, 1 mg / ml, 1.5 mg / ml, 2 mg / ml, 2.5 mg / ml, 3 mg / ml, 3.5 mg / ml, 4 mg / ml, 4.5 mg / ml, or 5 mg / ml.

[0026] In a preferred embodiment, the thickness of the electron transport layer obtained by the spin coating or blade coating treatment is 10 - 200 nm, such as 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, or 200 nm.

[0027] A third object of the present invention is to provide a fully solution-processed semi-transparent organic solar cell, which sequentially includes an anode, a hole transport layer, an organic active layer, an electron transport layer, and a cathode from bottom to top, and the electron transport layer is the electron transport layer described in the first object of the present invention or the electron transport layer obtained by using the preparation method described in the second object of the present invention.

[0028] Among them, the solar cell has a multi-layered structure, and the hole transport layer, the organic active layer, the electron transport layer, and the cathode are all prepared from solutions.

[0029] In a preferred embodiment, the anode is selected from the commonly used anode materials in the art, preferably but not limited to at least one of ITO, silver nanowires, and silver nanoparticles.

[0030] In a preferred embodiment, the hole transport layer is selected from the commonly used hole transport layer materials in the art, preferably but not limited to at least one of PEDOT:PSS and 2PACz.

[0031] In a preferred embodiment, the organic active layer is selected from the commonly used organic active layer materials in the art, preferably but not limited to a combination of an electron donor material and an electron acceptor material; more preferably, the electron donor material is selected from at least one of PM6, D18, PTQ10, and PCE10, and the electron acceptor material is selected from at least one of Y6, L8-BO, and BTP-eC9.

[0032] In a further preferred embodiment, in the organic active layer, the weight ratio of the electron donor material to the electron acceptor material is 1:(0.8 - 1.5), preferably 1:(1 - 1.3), such as 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5.

[0033] In a preferred embodiment, the cathode is a silver electrode. Preferably, the cathode is a silver electrode obtained by evaporation or a silver nanowire solution (for example, the silver electrode is obtained by evaporating or spin-coating or blade-coating the silver nanowire solution on the electron transport layer). More preferably, the silver nanowire solution is silver nanowires in an aqueous silver nanowire solution and / or an alcoholic silver nanowire solution, and preferably, the alcohol is selected from at least one of ethanol and isopropanol.

[0034] In a further preferred embodiment, in the silver nanowire solution, the concentration of silver nanowires is 0.1 - 1 wt%, preferably 0.3 - 0.5 wt%, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%.

[0035] Among them, the solution-processed silver nanowire electrode can realize a semi-transparent organic solar cell, and a fully solution-processed semi-transparent cell can be realized by adjusting the formulation of the interfacial layer and the solution-processed top electrode.

[0036] In a preferred embodiment, the cathode solution (such as a silver nanowire solution) is directly processed on the electron transport layer by spin coating or blade coating.

[0037] In a further preferred embodiment, the rotation speed of the spin coating is 1000 - 4000 rpm, preferably 2000 - 3000 rpm, for example 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm or 4000 rpm.

[0038] In a preferred embodiment, the lowermost layer of the solar cell further includes a substrate, which is connected to the anode.

[0039] In a further preferred embodiment, the substrate is selected from the commonly used substrates in the art, preferably but not limited to a glass substrate or a flexible substrate. More preferably, the flexible substrate is selected from at least one of PEN, PET, and PDMS.

[0040] In a preferred embodiment, the solar cell adopts a forward structure.

[0041] As a preferred solution of the organic solar cell described in the present application, wherein: the conductive substrate is an ITO substrate, and the hole transport layer is composed of PEDOT:PSS.

[0042] The fourth object of the present invention is to provide a method for preparing a semi-transparent organic solar cell by a full-solution process, including: (A) obtaining an anode, and sequentially preparing a hole transport layer and an organic active layer on the anode; (B) obtaining the dispersion liquid of the electron transport layer mixture, and spin coating or blade coating the dispersion liquid of the electron transport layer mixture onto the organic active layer to form an electron transport layer; (C) forming a cathode on the electron transport layer; wherein, the electron transport layer is obtained by using the preparation method described in the second object of the present invention.

[0043] In the present invention, in step (A), the hole transport layer and the organic active layer can be prepared by using the methods disclosed in the prior art, preferably but not limited to the following limitations.

[0044] In a preferred embodiment, the hole transport layer is obtained as follows: the material for forming the hole transport layer is spin coated or blade coated on the anode in the form of a solution, and the hole transport layer is formed after annealing treatment.

[0045] In a further preferred embodiment, the temperature of the annealing treatment is 25 - 150 °C, and the time is 5 - 30 min.

[0046] For example, the temperature of the annealing treatment is 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, and the time is 5 min, 10 min, 15 min, 20 min, 25 min or 30 min.

[0047] In a further preferred embodiment, the temperature of the annealing treatment is 90 - 110°C, and the time is 10 - 15 min.

[0048] In one embodiment of the present invention, the preparation of the hole transport layer includes: spin-coating (preferably at 2000 - 6000 rpm, more preferably at 3000 - 5000 rpm, for example 4300 rpm) the material of the hole transport layer (such as PEDOT:PSS solution) on the anode (such as ITO), and then performing annealing treatment (such as at a temperature of 140 - 150°C for 15 min).

[0049] In a preferred embodiment, the organic active layer is obtained as follows: spin-coating or blade-coating the material for forming the organic active layer in the form of a solution on the hole transport layer, and obtaining the organic active layer through annealing treatment.

[0050] In a further preferred embodiment, the conditions of the annealing treatment include: treating at 50 - 150°C for 0.5 - 20 min, preferably treating at 70 - 130°C for 1 - 10 min.

[0051] In one embodiment of the present invention, the organic active layer is obtained as follows: mixing an electron donor material (such as PM6) with an electron acceptor material (such as Y6 and / or L8BO), dispersing in a solvent (such as chloroform), and optionally adding an additive to obtain a dispersion of the organic active layer; spin-coating or blade-coating the dispersion of the organic active layer on the hole transport layer to obtain the organic active layer.

[0052] Preferably, the additive is selected from at least one of DIO, CN, DPE, and DCB.

[0053] Among them, the function of the additive is to adjust the morphology of the active layer.

[0054] For example: the organic photoactive layer is prepared by the following steps: weighing 8 mg of PM6 powder, 9.6 mg of Y6 powder or L8BO powder, dissolving in 1 ml of chloroform solution, stirring overnight at room temperature, then adding an additive and stirring for another 30 min to obtain an active layer solution, and spin-coating the active layer solution on the PEDOT:PSS layer after stirring to obtain the organic photoactive layer.

[0055] In a preferred embodiment, the preparation of the electron transport layer includes: (1) dispersing (preferably dissolving) a polymer in an organic solvent to obtain a polymer dispersion, and dispersing a metal oxide in an organic solvent to obtain a metal oxide dispersion; (2) mixing the polymer dispersion with the metal oxide dispersion to obtain an electron transport layer mixture dispersion; (3) spin-coating or blade-coating the electron transport layer mixture dispersion on the organic active layer to form an electron transport layer.

[0056] In a preferred embodiment, the cathode is obtained by evaporation, or by spin-coating or blade-coating with a silver nanowire solution.

[0057] In a further preferred embodiment, the silver nanowire solution is a silver nanowire in an aqueous solution and / or an alcohol solution. Preferably, the alcohol is selected from at least one of ethanol and isopropanol.

[0058] In a still further preferred embodiment, in the silver nanowire solution, the concentration of silver nanowires is 0.1 to 1 wt%, preferably 0.3 to 0.5 wt%, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1 wt%.

[0059] Among them, the solution-processed silver nanowire electrode can realize a semi-transparent organic solar cell, and a fully solution-processed semi-transparent cell can be realized by regulating the formulation of the interfacial layer and the solution-processed top electrode.

[0060] In a preferred embodiment, the cathode solution is directly processed on the electron transport layer by spin-coating.

[0061] In a further preferred embodiment, the rotation speed of the spin-coating is 1000 to 4000 rpm, preferably 2000 to 3000 rpm, such as 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm or 4000 rpm.

[0062] In one embodiment of the present invention: First, a hole transport layer material (such as PEDOT:PSS) is spin-coated or blade-coated on the surface of an anode (such as a transparent conductive glass with striped ITO on its surface) to form a hole transport layer, and then it is annealed; then, a mixed solution containing an electron donor material and an electron acceptor material is spin-coated or blade-coated on the hole transport layer (such as PEDOT:PSS) under an anhydrous and anaerobic environment to obtain an organic active layer; immediately after that, a dispersion liquid of an electron transport layer mixture (i.e., a blend solution of a metal oxide and a polymer) is spin-coated or blade-coated on the organic active layer to form an electron transport layer; finally, a silver nanowire solution with a certain concentration is spin-coated or blade-coated on the electron transport layer or a silver electrode is evaporated on the electron transport layer to obtain a solution-prepared semi-transparent cathode; ultimately, a semi-transparent organic solar cell device prepared entirely by solution is constructed.

[0063] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0064] Compared with the prior art, the present invention has the following beneficial effects: (1) The electron transport layer prepared by doping a polymer with a metal oxide in the present invention has denseness and thickness insensitivity; (2) The electron transport layer can withstand direct solution treatment of the top electrode (cathode), and has excellent solvent resistance and thickness insensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is the characteristic curve between the current density and voltage of the solar cells provided in Examples 1 to 4 and Comparative Example 1 of the present invention.

[0066] Figure 2 It is the characteristic curve between the current density and voltage of the solar cell provided in Example 6 of the present invention.

[0067] Figure 3 It is the characteristic curve between the current density and voltage of the solar cell provided in Example 5 of the present invention.

[0068] Figure 4 It is the characteristic curve between the current density and voltage of the solar cell provided in Example 7 of the present invention.

[0069] Figure 5This is the characteristic curve between the current density and voltage of the solar cell provided in Embodiment 8 of the present invention and Comparative Example 2. Detailed implementation manners

[0070] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the content of the present invention still fall within the protection scope of the present invention.

[0071] In addition, it should be noted that among the various specific technical features described in the following detailed implementation manners, they can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0072] Furthermore, any combination can be made between various different implementation manners of the present invention as long as it does not violate the idea of the present invention. The technical solutions formed thereby belong to a part of the original disclosure content of this specification and also fall within the protection scope of the present invention.

[0073] For the raw materials used in the examples and comparative examples, if not specifically defined, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0074]

Example 1

[0075] In Example 1, the average particle size of ZnONPs is 20 nm, and the molecular weight of the PVB polymer is 45,000.

[0076] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropanol, then dried, and further treated with ultraviolet ozone for 15 minutes; then a 10-nm-thick layer of PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotational speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Then the wafer was transferred to a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotational speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were respectively annealed at 100 °C for 5 minutes. An 8-mg / ml PVB methanol solution and a 40-mg / ml ZnONPs methanol dispersion were mixed at a volume ratio of 1:1, shaken, and a composite electron transport layer solution of ZnO-doped polymer was prepared, and then spin-coated on the active layer at 2000 rpm to form an electron transport layer with a thickness of 30 nm. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated using an evaporation instrument.

[0077] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the device were measured, as Figure 1 shown. The battery with a silver-plated electrode (opaque) prepared in this example shows that the nano-ZnO:polymer interfacial layer of the present invention also has excellent performance when used in a conventional device structure.

[0078]

Example 2

[0079] In Example 2, the average particle size of ZnONPs was 20 nm, and the molecular weight of the PvPy polymer was 60000.

[0080] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropanol, then dried, and further treated with ultraviolet ozone for 15 minutes. Then, a 10-nm-thick layer of PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Subsequently, the wafer was transferred to a glove box. A chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 and a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were respectively annealed at 100 °C for 5 minutes. An 8-mg / ml PvPy methanol solution and a 40-mg / ml ZnO NPs methanol dispersion were mixed at a volume ratio of 1:1, shaken, and a composite electron transport layer solution of ZnO-doped polymer was prepared, and then spin-coated on the active layer at 2000 rpm to form an electron transport layer with a thickness of 30 nm. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated using an evaporation instrument.

[0081] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the above three devices were measured, as Figure 1 shown. The battery (opaque) with a silver-plated electrode prepared in this example shows that the nano-ZnO:polymer interface layer of the present invention also has excellent performance when used in a conventional device structure.

[0082]

Example 3

[0083] In Example 3, the average particle size of ZnONPs was 20 nm, and the molecular weight of the PEI polymer was 25,000.

[0084] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropanol, then dried, and further treated with ultraviolet ozone for 15 minutes. Then, a 10-nm-thick PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Next, the wafer was transferred to a glove box. A chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were annealed at 100 °C for 5 minutes respectively. A 0.32-mg / ml PEI methanol solution and a 40-mg / ml ZnO NPs methanol dispersion were mixed at a volume ratio of 1:1 and shaken to prepare a composite electron transport layer solution of ZnO-doped polymer, which was then spin-coated on the active layer at 2000 rpm respectively to form an electron transport layer with a thickness of 30 nm. Finally, a 150-nm-thick Ag electrode (cathode) was deposited by an evaporation coater.

[0085] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the device were measured, as shown in Figure 1 . The battery with a silver-plated electrode (opaque) prepared in this example shows that the nano-ZnO:polymer interfacial layer of the present invention also has excellent performance when used in a conventional device structure.

[0086]

Example 4

[0087] In Example 4, the average particle size of ZnONPs was 20 nm, and the molecular weight of the PAA polymer was 25000.

[0088] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol, then dried, and further treated with ultraviolet ozone for 15 minutes; then a 10-nm-thick PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Then the wafer was transferred to a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were annealed at 100 °C for 5 minutes respectively. A 1 mg / ml PAA methanol solution and a 40 mg / ml ZnO NPs methanol dispersion were mixed in a volume ratio of 1:1, shaken, and a composite electron transport layer solution of ZnO-doped polymer was prepared, and then spin-coated on the active layer at 2000 rpm respectively to form an electron transport layer with a thickness of 30 nm. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated using an evaporation instrument.

[0089] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the device were measured, as Figure 1 shown. The battery with a silver-plated electrode (opaque) prepared in this example shows that the nano-ZnO:polymer interface layer of the present invention also has excellent performance when used in a conventional device structure.

[0090]

Example 5

[0091] In Example 5, the average particle size of ZnONPs was 20 nm, and the molecular weight of the PVB polymer was 25000.

[0092] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol, then dried, and further treated with ultraviolet ozone for 15 minutes. Then, a 10-nm-thick PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Next, the wafer was transferred to a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were respectively annealed at 100 °C for 5 minutes. 12 mg / ml, 8 mg / ml, and 4 mg / ml of PVB methanol solutions were respectively mixed evenly with 40 mg / ml of ZnO NPs dispersion liquid in a volume ratio of 1:1 to prepare three composite electron transport layer solutions of ZnO-doped polymers, and then spin-coated on the active layer to form an electron transport layer with a thickness of 30 nm. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated using an evaporation instrument to obtain three devices with different electron transport layers.

[0093] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the above three devices were tested, as Figure 3 shown. It can be seen from Figure 3 that the optimal addition amount of the polymer in the electron transport layer of the present invention is 20 wt% (based on 100 wt% of the nano-zinc oxide particles). 10%, 20%, and 30% in the figure refer to the mass ratio of PVB to nano-zinc oxide particles (which can also be understood as the percentage of PVB in the nano-zinc oxide particles). Taking the example of mixing 8 mg / ml of PVB methanol solution and 40 mg / ml of ZnONPs dispersion liquid evenly in a volume ratio of 1:1, 8 mg / ml divided by 40 mg / ml is 20 wt%.

[0094] The battery with a silver-plated electrode (opaque) prepared in this example shows that the nano-ZnO:polymer interface layer of the present invention also has excellent performance when used in a conventional device structure.

[0095]

Example 6

[0096] In Example 6, the average particle size of ZnONPs was 20 nm, and the molecular weight of the P4VP polymer was 60000.

[0097] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol, then dried, and further treated with ultraviolet ozone for 15 minutes. Then, a 10-nm-thick PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Subsequently, the wafer was transferred into a glove box. A chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were annealed at 100 °C for 5 minutes respectively. Methanol solutions of P4VP with concentrations of 12 mg / ml, 8 mg / ml, and 4 mg / ml were respectively mixed evenly with a 40-mg / ml ZnO NPs dispersion liquid at a volume ratio of 1:1 to prepare three composite electron transport layer solutions of ZnO-doped polymers, and then spin-coated on the active layer to form electron transport layers with thicknesses of 30 nm respectively. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated using an evaporation instrument to obtain three devices with different electron transport layers.

[0098] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the above three devices were tested, as shown in Figure 2 . It can be seen from Figure 2 that the optimal addition amount of the polymer in the electron transport layer of the present invention is 20 wt% (calculated based on 100 wt% of the nano-zinc oxide particles). 10%, 20%, and 30% in the figure refer to the mass ratio of P4VP to the nano-zinc oxide particles (which can also be understood as the percentage of P4VP in the nano-zinc oxide particles). Taking the methanol solution of P4VP with a concentration of 8 mg / ml and the 40-mg / ml ZnO NPs dispersion liquid mixed evenly at a volume ratio of 1:1 as an example, 8 mg / ml divided by 40 mg / ml is 20 wt%.

[0099]

Example 7

[0100] In Example 7, the average particle size of ZnONPs was 20 nm, and the molecular weight of the PVB polymer was 25000.

[0101] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol, then dried, and further treated with ultraviolet ozone for 15 minutes. Then, a 10-nm-thick layer of PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Subsequently, the wafer was transferred into a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were annealed at 100 °C for 5 minutes respectively.

[0102] Composite electron transport layer solutions with three different concentrations of ZnO-doped polymers were prepared respectively: A composite electron transport layer solution I was obtained by uniformly mixing an 8-mg / mL PVB methanol solution and a 40-mg / mL ZnO NPs dispersion liquid in a volume ratio of 1:1, a composite electron transport layer solution II was obtained by uniformly mixing a 4-mg / mL PVB methanol solution and a 20-mg / mL ZnO NPs dispersion liquid in a volume ratio of 1:1, and a composite electron transport layer solution III was obtained by uniformly mixing a 2-mg / mL PVB methanol solution and a 10-mg / mL ZnO NPs dispersion liquid in a volume ratio of 1:1.

[0103] The composite electron transport layer solution I, composite electron transport layer solution II, and composite electron transport layer solution III were spin-coated on the active layer independently at 2000 rpm respectively to form electron transport layers with thicknesses of 60 nm, 50 nm, and 40 nm respectively. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated independently using an evaporation instrument to obtain three devices with different thickness electron transport layers.

[0104] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the above three devices were tested, as shown in Figure 4 . Among them, 60 nm, 50 nm, and 40 nm refer to the thickness of the electron transport layer. In this example, three devices were prepared, corresponding to three devices with different electron transport layer thicknesses prepared from the composite electron transport layer solution I, composite electron transport layer solution II, and composite electron transport layer solution III respectively.

[0105] It can be seen from Figure 4 that the J-V curves of the devices with three different thickness electron transport layers have no obvious difference. Therefore, the thickness has little influence on the device performance, so it can be said that the electron transport layer of the present invention has thickness insensitivity.

[0106]

Example 8

[0107] In Example 8, the average particle size of ZnONPs is 20 nm, and the molecular weight of the PVB polymer is 25,000.

[0108] The transparent conductive glass with striped ITO (anode) etched on its surface is successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol, then dried, and then treated with ultraviolet ozone for 15 minutes; then a 10-nm-thick PEDOT:PSS-TA is spin-coated on the surface of the conductive glass at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Then the wafer is transferred to a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% chloronaphthalene (CN) is spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers are respectively annealed at 100 °C for 5 min. An 8-mg / ml PVB methanol solution is mixed with a 40-mg / ml ZnO NPs dispersion liquid evenly at a volume ratio of 1:1 and spin-coated on the active layer at 2000 r. A pure ZnO electron transport layer is used for the control device. Finally, a 0.3-wt% aqueous silver nanowire is spin-coated on the electron transport layer. Two all-solution-processed devices with different electron transport layers are obtained.

[0109] Under the AM1.5 simulated sunlight irradiation with a light intensity of 100 mW / cm 2 , the current-voltage curves of the above two devices are tested, as Figure 5 .

[0110] From Figure 5 , it can be seen that the ZnO:polymer electron transport layer of the present invention can withstand the direct solution-processed top electrode.

[0111] Compared with the pure ZnO electron transport layer, the electron transport layer of the present invention using a mixture of metal oxide and polymer improves the power conversion efficiency (PCE) of the opaque device by about 20% (i.e., the power conversion efficiency (PCE) of the transparent device with a solution-processed top electrode is increased by about 152% [(9.34 - 3.71) / 3.71]. In addition, the corresponding semi-transparent organic solar cells obtained efficiencies exceeding 9% and an average visible transmittance (AVT) of 29% after solution-processing top electrodes with different concentrations of silver nanowires, meeting the basic application requirements for semi-transparent organic solar cells.

[0112] The average transmittance AVT is calculated by the formula, where T represents the transmittance spectrum of the device, P represents the spectral response of the human eye, S represents the solar spectrum of AM1.5G, and the integration range is the visible light region of 380 - 760 nm:

[0113]

[0114]

Comparative Example 1

[0115] The transparent conductive glass with striped ITO (anode) on the surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone and isopropanol, dried, and then treated with ultraviolet ozone for 15 minutes; then a 10-nm-thick PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Then the wafer was transferred to a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were annealed at 100 °C for 5 min respectively. A 20-mg / ml ZnO NPs methanol dispersion was used as the electron transport layer solution, and then spin-coated on the active layer at 2000 rpm. Finally, a 150-nm-thick Ag electrode (cathode) was evaporated using an evaporation instrument.

[0116] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curve of the device was tested, as Figure 1 shown.

[0117] It can be seen from Figure 1 that the relevant performance of the batteries prepared in Examples 1-4 of the present invention is superior to that of the battery with pure ZnO NPs as the electron transport layer in Comparative Example 1.

[0118]

Comparative Example 2

[0119] The transparent conductive glass with striped ITO (anode) on its surface was successively ultrasonically cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol, then dried, and further treated with ultraviolet ozone for 15 minutes. Then, a 10-nm-thick layer of PEDOT:PSS-TA was spin-coated on the conductive glass surface at a rotation speed of 4500 rpm, and then annealed at 170 °C for 20 minutes. Subsequently, the wafer was transferred to a glove box, and a chloroform solvent mixture prepared by mixing a binary system (PM6:Y6) with a weight ratio of 1:1.2 at a total donor-acceptor concentration of 13.2 mg / mL and adding 0.5% of chloronaphthalene (CN) was spin-coated at a rotation speed of 2000 rpm for 30 seconds to obtain an active layer with a thickness of 100 nm respectively. The above active layers were annealed at 100 °C for 5 minutes respectively. A 20-mg / ml ZnO NPs methanol dispersion was used as the electron transport layer solution and spin-coated on the active layer at 2000 rpm. Finally, a 0.3-wt% aqueous silver nanowire was spin-coated on the electron transport layer. A fully solution-processed device was obtained.

[0120] Under the irradiation of AM1.5 simulated sunlight with an illumination intensity of 100 mW / cm 2 , the current-voltage curves of the above devices were tested, as shown in Figure 5 .

[0121] Table 1: Battery performance tests of Examples 1-4 and Comparative Example 1

[0122]

[0123] As can be seen from Table 1, PVB has the best effect, the highest PCE, and more balanced parameters.

[0124] Table 2: Battery performance tests of Example 8 and Comparative Example 2

[0125]

[0126] Among them, the battery performance tests described in Table 1 and Table 2 are tests of the efficiency of photovoltaic devices. Voc is the open-circuit voltage, Jsc is the short-circuit current density, FF is the fill factor, PCE is the energy conversion efficiency, and PCE = (Voc x Jsc x FF) / Pin. Pin refers to the light intensity of the solar simulator during the test, which is 100 mW / cm 2 .

[0127] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. An electron transport layer, which is a blend film of metal oxide nanoparticles and a polymer.

2. The electron transport layer according to claim 1, wherein, the metal oxide nanoparticles are selected from at least one of zinc oxide nanoparticles and tin dioxide nanoparticles; and / or, the polymer is selected from at least one of PVP, PVB, PEO, PEI, P4VP, and PAA.

3. The electron transport layer according to claim 1, wherein, in the electron transport layer, the weight ratio of the metal oxide nanoparticles to the polymer is 100:(10 - 50), preferably 100:(10 - 30).

4. The electron transport layer according to any one of claims 1 to 3, wherein, the thickness of the electron transport layer is 10 - 200 nm, preferably 30 - 60 nm.

5. A method for preparing the electron transport layer according to any one of claims 1 to 4, comprising: (1) Dispersing the polymer in an organic solvent to obtain a polymer dispersion, and dispersing the metal oxide in an organic solvent to obtain a metal oxide dispersion; (2) Mixing the polymer dispersion and the metal oxide dispersion to obtain an electron transport layer mixture dispersion; (3) Subjecting the electron transport layer mixture dispersion to spin coating or blade coating treatment to form an electron transport layer.

6. The preparation method according to claim 5, wherein, the organic solvent in step (1) is selected from alcohol solvents, preferably at least one of methanol, ethanol, butanol, and isopropanol; more preferably, in the electron transport layer mixture dispersion, the concentration of the metal oxide is 5 - 30 mg / ml, and / or, the concentration of the polymer is 0.5 - 5 mg / ml.

7. The preparation method according to claim 5 or 6, wherein, the thickness of the electron transport layer obtained by the spin coating or blade coating treatment is 10 - 200 nm.

8. A fully solution-processed semi-transparent organic solar cell, which sequentially includes an anode, a hole transport layer, an organic active layer, an electron transport layer, and a cathode from bottom to top, and the electron transport layer is the electron transport layer according to any one of claims 1 to 4 or the electron transport layer obtained by using the preparation method according to any one of claims 5 to 7.

9. The fully solution-processed semi-transparent organic solar cell according to claim 8, wherein, the anode is selected from at least one of ITO, silver nanowires, and silver nanoparticles; and / or, the hole transport layer is selected from hole transport layer materials commonly used in the art, preferably at least one of PEDOT:PSS and 2PACz; and / or, the organic active layer is selected from a combination of an electron donor material and an electron acceptor material; more preferably, the electron donor material is selected from at least one of PM6, D18, PTQ10, and PCE10, and the electron acceptor material is selected from at least one of Y6, L8-BO, and BTP-eC9.

10. The fully solution-processed semi-transparent organic solar cell according to claim 8 or 9, wherein, The cathode is a silver electrode. Preferably, the cathode is a silver vapor deposition or a silver nanowire solution. More preferably, the silver nanowire solution is an aqueous silver nanowire solution and / or an alcoholic silver nanowire solution.

11. The all-solution-processed semi-transparent organic solar cell according to claim 10, wherein, the cathode solution is directly processed on the electron transport layer by spin coating or blade coating.

12. A method for preparing an all-solution-processed semi-transparent organic solar cell, comprising: (A) obtaining an anode, and sequentially preparing a hole transport layer and an organic active layer on the anode; (B) obtaining the dispersion liquid of the electron transport layer mixture, and spin coating or blade coating the dispersion liquid of the electron transport layer mixture onto the organic active layer to form an electron transport layer; (C) forming a cathode on the electron transport layer; wherein, the electron transport layer is the electron transport layer according to any one of claims 1 to 4 or the electron transport layer obtained by using the preparation method according to any one of claims 5 to 7.

13. The preparation method according to claim 12, wherein, the hole transport layer is obtained as follows: the material for forming the hole transport layer is spin coated or blade coated on the anode in the form of a solution, and the hole transport layer is formed after annealing treatment; preferably, the temperature of the annealing treatment is 25 to 150 °C and the time is 5 to 30 min; and / or, the organic active layer is obtained as follows: the material for forming the organic active layer is spin coated or blade coated on the hole transport layer in the form of a solution, and the organic active layer is obtained after annealing treatment; preferably, the conditions of the annealing treatment include: treating at 50 to 150 °C for 0.5 to 20 min; and / or, the dispersion liquid of the organic active layer is spin coated or blade coated on the hole transport layer to obtain the organic active layer; and / or, the cathode is obtained by vapor deposition or is obtained by spin coating or blade coating with a silver nanowire solution.

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