Composition for electron transport layer, organic solar cell device and preparation method of organic solar cell device

Abstract

The invention relates to the field of organic solar cells, in particular to a composition for an electron transport layer, an organic solar cell device and a preparation method of the organic solar cell device, the composition contains a metal oxide and an organic acid additive, the organic acid additive is selected from one or more of a compound shown in a formula (1) or a compound shown in a formula (2), the substituents R1, R2, R3, R4, R5, R6 and n in formula (1) and formula (2) have specific definitions. The organic acid additive is adopted to modify the metal oxide, carrier recombination is reduced, interface contact is optimized, meanwhile, the composition layers assembled layer by layer can reduce damage of a magnetron sputtering process to the active layer, the photoelectric conversion efficiency of an organic solar cell device is improved, and the organic solar cell device has good translucency and stability. Formula (1) and formula (2).

Description

Technical Field

[0001] This invention relates to the field of organic solar cells, and more specifically, to a composition for an electron transport layer, an organic solar cell device, and a method for preparing the same. Background Technology

[0002] Organic solar cells, with their core advantages of flexibility, low manufacturing cost, light weight, and large-area printing fabrication, have shown irreplaceable application potential in fields such as flexible electronics, portable device power supply, and building-integrated photovoltaics. With technological iteration and evolving market demands, organic solar cells are gradually transforming from "single power generation function" to "multifunctional integrated devices," with semi-transparent light transmittance, high stability, and broad spectral response becoming core performance requirements.

[0003] To achieve the aforementioned functions, advanced processes such as magnetron sputtering, solution spin coating, and inkjet printing are widely used. Among them, magnetron sputtering, due to its ability to fabricate transparent top electrodes with high conductivity and high light transmittance, has become a key technology for ensuring the charge collection efficiency of devices. However, the layer-by-layer assembly characteristics of organic solar cells lead to significant technical bottlenecks in the magnetron sputtering process. For example, high-energy particle bombardment can directly cause the organic molecular chains within the active layer to break and reduce crystallinity, thereby reducing the efficiency of photogenerated carrier generation and transport, severely affecting the photoelectric conversion efficiency and long-term stability of the device.

[0004] While existing technologies have proposed using ion beam sputtering to replace magnetron sputtering in order to protect the integrity of the battery's various layers, they still haven't proposed a solution to the problem of damage to the active layer caused by magnetron sputtering in the fabrication of the transparent top electrode. Furthermore, the electron transport layer, as the key interface layer connecting the active layer and the transparent top electrode, suffers from carrier recombination caused by surface defects (such as oxygen vacancies) and excessively high interfacial contact impedance, further limiting the improvement of device performance.

[0005] Therefore, developing an electron transport layer that can optimize interface characteristics and effectively reduce damage to the active layer caused by magnetron sputtering has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide an electron transport layer composition, an organic solar cell device, and a method for fabricating the same. This electron transport layer composition can prevent damage to the active layer during magnetron sputtering and optimize the interface characteristics of the electron transport layer, thereby significantly improving the photoelectric efficiency, translucency, and stability of the organic solar cell.

[0007] To achieve the above objectives, the present invention provides a composition for an electron transport layer, the composition comprising a metal oxide and an organic acid additive, wherein the organic acid additive is selected from one or more compounds represented by formula (1) or formula (2): Equation (1) Equation (2) ; Wherein, R1 is selected from one or more of the following: a linking bond, a C1-C12 alkylene group, and a C2-C12 alkenyl group; each R2 is independently selected from one or more of H and a C1-C12 alkyl group; R3 and R4 are independently selected from one or more of H and a C1-C12 alkoxy group; R5 is selected from one or more of hydroxyl groups or hydroxyl-containing groups, or R5 is cyclized with R3 or R4 to form an oxygen-containing heterocycle; R6 is selected from one or more of the following: a linking bond, a C1-C12 alkylene group, and a C2-C12 alkenyl group; and n is an integer from 1 to 8.

[0008] A second aspect of the present invention provides an organic solar cell device comprising an electron transport layer, the electron transport layer comprising at least one composition layer comprising the composition for the electron transport layer described above.

[0009] A third aspect of the present invention provides a method for preparing the above-mentioned organic solar cell device, the method comprising: applying an electron transport layer composition to the surface of an active layer to obtain at least one composition layer.

[0010] This invention addresses two key aspects. First, by introducing a synergistic system of metal oxide and organic acid additives into the electron transport layer, the organic acid additives can target and bind to defect sites (such as oxygen vacancies) on the metal oxide surface. This reduces carrier recombination losses within the electron transport layer, optimizes the interfacial contact characteristics between the electron transport layer and the active layer, lowers the interfacial charge transport barrier, and accelerates electron migration from the active layer to the transparent top electrode. Second, improvements are made to the electron transport layer fabrication process. By assembling composite layers layer by layer on the outer surface of the active layer to form a dense electron transport layer, damage to the active layer during magnetron sputtering is effectively reduced. The combined effect of these two aspects ultimately achieves a synergistic improvement in the device's photoelectric conversion efficiency, translucency, and stability. Attached Figure Description

[0011] Figure 1 The current density-voltage curve (JV curve) of the solar cell obtained in Example 1 is shown.

[0012] Figure 2 The visible light transmittance curve is shown for the solar cell obtained in Example 1.

[0013] Figure 3The JV curve is shown for the solar cell obtained in Example 2.

[0014] Figure 4 The visible light transmittance curve is shown for the solar cell obtained in Example 2.

[0015] Figure 5 The JV curve is shown for the solar cell obtained in Example 3.

[0016] Figure 6 The visible light transmittance curve is shown for the solar cell obtained in Example 3.

[0017] Figure 7 The JV curve is shown for the solar cell obtained in Example 4.

[0018] Figure 8 The visible light transmittance curve is shown for the solar cell obtained in Example 4.

[0019] Figure 9 The JV curve is shown for the solar cell obtained in Comparative Example 1.

[0020] Figure 10 The visible light transmittance curve is shown for the solar cell obtained in Comparative Example 1. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] In this invention, the alkyl group in expressions such as "C1-C12 alkyl" and "C1-C6 alkyl" can be either a straight-chain alkyl group or a branched alkyl group. The same applies to other similar expressions, such as the alkyl portion in "C1-C6 alkoxy," which can be either straight-chain or branched, and so on.

[0023] In this invention, "R5 is ringed with R3 or R4 to form..." "Key" refers to the ability of R5 to loop with R3. Key, to get something like " The compound shown; or, R5 can cyclize with R4 to form Key, to get something like " The compound shown.

[0024] In one aspect, the present invention provides a composition for an electron transport layer, the composition comprising a metal oxide and an organic acid additive, wherein the organic acid additive is selected from one or more compounds represented by formula (1) or formula (2): Equation (1) Equation (2) ; Wherein, R1 is selected from one or more of the following: a linking bond, a C1-C12 alkylene group, and a C2-C12 alkenyl group; each R2 is independently selected from one or more of H and a C1-C12 alkyl group; R3 and R4 are independently selected from one or more of H and a C1-C12 alkoxy group; R5 is selected from one or more of hydroxyl groups or hydroxyl-containing groups, or R5 is cyclized with R3 or R4 to form an oxygen-containing heterocycle; R6 is selected from one or more of the following: a linking bond, a C1-C12 alkylene group, and a C2-C12 alkenyl group; and n is an integer from 1 to 8.

[0025] According to the present invention, in order to obtain organic solar energy devices with better performance, the structures of the compounds shown in formula (1) and formula (2) can be further selected. Preferably, R1 is selected from one or more of the following: a linking bond, a C1-C6 alkylene group, and a C2-C6 alkenyl group; each R2 is independently selected from one or more of H and C1-C6 alkyl groups; R3 and R4 are independently selected from one or more of H and C1-C6 alkoxy groups; R5 is selected from one or more of hydroxyl and C1-C6 hydroxyalkyl groups, or R5 is cyclized with R3 or R4 to form Bond; R6 is selected from one or more of the following: linking bond, C1-C6 alkylene group and C2-C6 alkenyl group; n is an integer from 1 to 6.

[0026] More preferably, R1 is selected from one or more of the following: a linking bond, a C1-C3 alkylene group, and a C2-C4 alkenyl group; each R2 is independently selected from one or more of H and C1-C3 alkyl groups; R3 and R4 are each independently selected from one or more of H and C1-C3 alkoxy groups; R5 is selected from one or more of hydroxyl and C1-C3 hydroxyalkyl groups, or R5 is cyclized with R3 or R4 to form Bond; R6 is selected from one or more of the following: linking bond, C1-C3 alkylene group and C2-C4 alkenyl group; n is an integer from 2 to 4.

[0027] More preferably, R1 is selected from one or more of the following: a linking bond, -CH2-, -CH2CH2-, -CH=CH-, -CH=CH-CH2-, and -CH=CH-CH2-CH2-; each R2 is independently selected from one or more of H, -CH3, -CH2CH3, and -CH2CH2CH3; R3 and R4 are each independently selected from one or more of H, -OCH3, -OCH2CH3, and -OCH2CH2CH3; R5 is selected from one or more of -OH, -CH2OH, -CH2CH2OH, and -CH2CH2CH2OH, or R5 is cyclic with R3 or R4 to form R6 is selected from one or more of the following: linker, -CH2-, -CH2CH2-, -CH=CH-, and -CH=CH-CH2-; n is 2 or 3.

[0028] According to a preferred embodiment of the present invention, the compound represented by formula (1) is selected from one or more compounds represented by the following formulas: .

[0029] According to a particularly preferred embodiment of the present invention, the compound represented by formula (1) is selected from one or more of the compounds represented by formula (1-1), formula (1-2), formula (1-3), formula (1-4), and formula (1-5).

[0030] According to a preferred embodiment of the present invention, the compound represented by formula (2) is selected from one or more compounds represented by the following formulas: .

[0031] According to a particularly preferred embodiment of the present invention, the compound represented by formula (2) is selected from one or more of the compounds represented by formula (2-1), formula (2-2), formula (2-3), and formula (2-4).

[0032] According to the present invention, in order to further optimize the interaction between the organic acid additive and the metal oxide, reduce carrier recombination and improve interfacial compatibility, the weight ratio of the metal oxide to the organic acid additive is preferably 1:0.05-1, more preferably 1:0.2-0.4, for example, it can be 1:0.2, 1:0.33 and 1:0.4 and any range between these values.

[0033] According to the present invention, the metal oxide may be appropriately selected from metal oxides for electron transport layers of organic solar cells, preferably selected from one or more of ZnO, TiO2 and SnO2, and more preferably ZnO and / or SnO2.

[0034] According to the present invention, the particle size of the metal oxide can be selected in a wide range, as long as it can meet the requirements for constructing an electron transport layer. In order to obtain better electron transport performance, the average particle size of the metal oxide is preferably 3-20 nm, more preferably 5-10 nm, for example, it can be 5 nm, 6 nm, 8 nm and 10 nm and any value between them.

[0035] A second aspect of the present invention provides an organic solar cell device comprising an electron transport layer, the electron transport layer comprising at least one composition layer comprising the composition for the electron transport layer described above.

[0036] According to the present invention, preferably, the organic solar cell device includes a conductive substrate, a hole transport layer, an active layer, an electron transport layer and a transparent top electrode arranged sequentially from bottom to top.

[0037] According to the present invention, in order to ensure the charge transport rate of the electron transport layer and avoid light absorption loss or resistance increase caused by excessive thickness, the thickness of the electron transport layer is preferably 55-125 nm, more preferably 60-120 nm, for example, it can be 60 nm, 80 nm, 110 nm and 120 nm and any value between them.

[0038] According to the present invention, in order to reduce the loss of the active layer during the fabrication of a transparent top electrode by magnetron sputtering, the thickness of the composition layer is preferably 1-125 nm, more preferably 5-120 nm, for example, it can be 5 nm, 20 nm, 40 nm, 60 nm, 80 nm and 120 nm, or any value between these values. Preferably, the number of composition layers is 1-5 layers, more preferably 2-4 layers, for example, 2 layers, 3 layers or 4 layers.

[0039] According to the present invention, the material of the conductive substrate can be selected from a wide range, such as indium tin oxide (ITO), indium zinc oxide (IZO) and aluminum-doped zinc oxide (AZO) and other materials commonly used in the art.

[0040] According to the present invention, the hole transport material used in the hole transport layer can be selected from a wide range. To obtain good hole mobility and improve the photoelectric efficiency of the organic solar cell device, preferably, the hole transport material used in the hole transport layer can be selected from one or more of poly(3,4-ethylenedioxythiophene)-(polystyrene sulfonate), [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, CuSCN, and MoO3. Poly(3,4-ethylenedioxythiophene)-(polystyrene sulfonate) can also be called PEDOT:PSS(Al4083). All of the above hole transport materials can be prepared using existing literature or obtained commercially.

[0041] According to the present invention, the thickness of the hole transport layer can be selected within a wide range. In order to obtain better results and improve hole extraction efficiency and device energy conversion efficiency, the thickness of the hole transport layer is preferably 1-120 nm, more preferably 20-100 nm, for example, it can be 25 nm, 50 nm, 70 nm and 100 nm and any value between them.

[0042] According to the present invention, the active layer comprises an electron donor material and an electron acceptor material, wherein the electron donor material may be selected from one or more polymers containing repeating structural units shown in formulas (3-1), (3-2), and (3-3): Equation (3-1) , Equation (3-2) , Equation (3-3) ; Wherein, -C4H9 is n-butyl, -C6H 13 To establish a sound foundation for oneself.

[0043] According to the present invention, the polymer composed of repeating structural units shown in formula (3-1) is also called PM6; the polymer composed of repeating structural units shown in formula (3-2) is also called PTB7-Th; and the polymer composed of repeating structural units shown in formula (3-3) is also called D18.

[0044] According to the present invention, the electron acceptor material may be selected from one or more compounds shown in formula (4-1), formula (4-2), formula (4-3) and formula (4-4): Equation (4-1) , Equation (4-2) , Equation (4-3) , Equation (4-4) ; Wherein, -C4H9 is n-butyl; -C6H 13 For ortho-hexane; -C9H 19 It is a positive base; -C 11 H 23 It is n-undecyl. The compound represented by formula (4-1) is also called L8-BO; the compound represented by formula (4-2) is also called BTP-eC9; the compound represented by formula (4-3) is also called Y6; the compound represented by formula (4-4) is also called BO-4Cl.

[0045] The aforementioned materials may be commercially available products or prepared by conventional methods in the art as disclosed in the literature. Among them, PM6 can be prepared by the method provided in the literature "Adv. Mater. 2015, 27, 4655–4660", BTP-eC9 can be prepared by the method provided in the literature "Adv. Mater. 2020, 32, 1908205", and the other materials are not listed one by one.

[0046] According to the present invention, in order to balance the light absorption efficiency and the carrier transport efficiency, reduce charge recombination and improve the energy conversion efficiency of the device, the thickness of the active layer is preferably 60-100 nm, more preferably 70-90 nm, for example, it can be 70 nm, 75 nm, 80 nm and 90 nm and any value between them.

[0047] According to the present invention, the material of the transparent top electrode can be selected from a wide range, such as indium tin oxide (ITO), indium zinc oxide (IZO) and aluminum-doped zinc oxide (AZO) and other materials commonly used in the art.

[0048] According to the present invention, in order to balance the conductivity and light transmittance of the transparent top electrode, the thickness of the transparent top electrode is preferably 70-130 nm, more preferably 80-120 nm, for example, it can be 80 nm, 100 nm, 110 nm and 120 nm and any value between them.

[0049] A third aspect of the present invention provides a method for preparing the above-mentioned organic solar cell device, the method comprising: applying an electron transport layer composition to the surface of an active layer to obtain at least one composition layer.

[0050] According to the present invention, preferably, the method of applying the electron transport layer composition to the surface of the active layer includes: coating a solution of the electron transport layer composition onto the surface to be coated and performing an annealing treatment to obtain the composition layer. The surface to be coated is related to the number of composition layers. When preparing the first composition layer, the surface to be coated is the outer surface of the active layer. When the first composition layer is prepared and a second composition layer is prepared on top of the first composition layer, the surface to be coated is the outer surface of the first composition layer. And so on. The details are not elaborated further here.

[0051] According to the present invention, in order to obtain an ideal composition layer, the concentration of each material in the solution of the composition for the electron transport layer, the amount of solution used, and the solvent used can be adjusted. Preferably, the concentration of the metal oxide in the solution of the composition for the electron transport layer is 10-20 mg / mL, more preferably 15-18 mg / mL, for example, it can be 15 mg / mL, 16 mg / mL, 17.6 mg / mL and 18 mg / mL, and any range between these values.

[0052] Preferably, the concentration of the organic acid additive in the solution of the composition for the electron transport layer is 1-10 mg / mL, more preferably 3-7.5 mg / mL, for example, it can be 3 mg / mL, 5 mg / mL, 6 mg / mL and 7.5 mg / mL and any range between these values.

[0053] Preferably, when preparing a single layer of the composition, the amount of the solution of the composition for the electron transport layer is 0.02-1 mL, preferably 0.07-0.8 mL, for example, it can be 0.07 mL, 0.24 mL, 0.33 mL, 0.43 mL and 0.75 mL and any range between these values.

[0054] Preferably, the solvent of the solution of the electron transport layer composition is selected from one or more of n-butanol, chlorobenzene, chloroform, xylene, acetone and methanol.

[0055] According to the present invention, in order to obtain a composition layer that meets the desired requirements, so as to better balance the density of the composition layer with the continuity of the electron transport channels, while promoting the interfacial interaction between the organic acid additive and the metal oxide to reduce carrier recombination, preferably, the annealing conditions include: a temperature of 140-180 °C and a time of 8-25 min. More preferably, the annealing conditions include: a temperature of 150-170 °C (e.g., values ​​such as 150 °C, 155 °C, 160 °C, and 170 °C, and any range thereof), and a time of 10-20 min (e.g., values ​​such as 10 min, 13 min, 15 min, and 20 min, and any range thereof).

[0056] According to the present invention, the method for fabricating the organic solar cell device further includes: forming a hole transport layer on a conductive substrate, forming an active layer on the outer surface of the hole transport layer, forming an electron transport layer on the outer surface of the active layer, and forming a transparent top electrode on the outer surface of the electron transport layer.

[0057] According to the present invention, the method for preparing the hole transport layer may include: coating a solution of the hole transport material onto the surface of the conductive substrate and performing a first annealing treatment to obtain the hole transport layer. The concentration of the hole transport material solution may be 1.3-1.7 wt%, the solvent of the hole transport material solution may be water, and the amount of the hole transport material solution may be 10-30 μL. The conditions for the first annealing treatment may be: a temperature of 140-180℃ and a time of 8-25 min.

[0058] According to the present invention, the method for preparing the active layer may include: coating a mixed solution containing the electron donor material and the electron acceptor material onto the surface of the hole transport layer and then drying it to obtain the active layer. The concentration of the electron donor material in the mixed solution may be 2-10 mg / mL. The concentration ratio of the electron donor material to the electron acceptor material may be 1:1-10. The volume of the mixed solution of the electron donor material and the electron acceptor material may be 0.3-2 mL. The solvent of the mixed solution of the electron donor material and the electron acceptor material may be selected from one or more of chlorobenzene, chloroform, xylene, acetone, and methanol. The drying conditions may be: a temperature of 80-120°C and a time of 3-7 min. Preferably, the drying is carried out in a non-reactive gas atmosphere, such as nitrogen and / or argon.

[0059] According to the present invention, the coating method described above can be a conventional method in the art, such as spin coating, blade coating, printing, or sputtering. To obtain a higher quality organic solar cell device, spin coating is preferably used. Specifically, the spin coating conditions for the hole transport layer are typically: rotation speed 3000-5000 rpm, time 30-60 s. The spin coating conditions for the active layer are: rotation speed 1500-3000 rpm, time 30-80 s. The spin coating conditions for the electron transport layer are: rotation speed 2000-4000 rpm, time 30-60 s.

[0060] According to the present invention, in order to ensure that the transparent top electrode possesses high conductivity and light transmittance, the transparent top electrode is fabricated by magnetron sputtering. Preferably, the conditions for the magnetron sputtering process include: a vacuum degree of 5 × 10⁻⁶. -6 -1×10 -4 Pa, sputtering power of 50-150 W. More preferably, the conditions for the magnetron sputtering process include: a vacuum degree of 1×10⁻⁶ Pa. -5 -5×10 -5 Pa (for example, it can be 1×10) -5 Pa, 2×10 -5 Pa, 3×10 -5 Pa and 4×10 -5 The sputtering power is 80-120 W (for example, it can be 80 W, 90 W, 100 W and 120 W and the range between any values).

[0061] This invention addresses two key aspects. First, by introducing a synergistic system of metal oxide and organic acid additives into the electron transport layer, the organic acid additives can target and bind to defect sites (such as oxygen vacancies) on the metal oxide surface. This reduces carrier recombination losses within the electron transport layer, optimizes the interfacial contact characteristics between the electron transport layer and the active layer, lowers the interfacial charge transport barrier, and accelerates electron migration from the active layer to the transparent top electrode. Second, improvements are made to the electron transport layer fabrication process. By assembling composite layers layer by layer on the outer surface of the active layer to form a dense electron transport layer, damage to the active layer during magnetron sputtering is effectively reduced. The combined effect of these two aspects ultimately achieves a synergistic improvement in the device's photoelectric conversion efficiency, translucency, and stability.

[0062] The present invention will be described in detail below through embodiments.

[0063] In the following examples: Using the SS-X50 solar simulator from Guangyan Technology Co., Ltd. and an AM1.5G solar spectral filter, at 100 mW·cm⁻¹... -2Photovoltaic performance tests were conducted on the devices under varying light intensity. The light intensity was calibrated using a standard polycrystalline silicon solar cell (SRC2020). The current-voltage curve (JV curve) was obtained using a Keysight B2901A Source Meter under a nitrogen atmosphere in a glove box. Parameters such as short-circuit current, open-circuit voltage, fill factor, and photoelectric conversion efficiency can be obtained from the JV curve.

[0064] The visible light transmission spectrum was obtained by measuring with a Shimadzu UV-2600i UV-Vis spectrophotometer.

[0065] The thickness of each layer of the organic solar cell was measured using a Dektak XT model step meter.

[0066] All materials may be commercially available or prepared by conventional methods in the art as disclosed in the literature. PEDOT:PSS (Al4083) was purchased from Heraeus Inc. PM6 was prepared by the method described in "Adv. Mater. 2015, 27, 4655–4660" (weight-average molecular weight 38600 g / mol, molecular weight distribution coefficient 2). BTP-eC9 was prepared by the method described in "Adv. Mater. 2020, 32, 1908205". In the following examples and comparative examples, the organic acid additives and metal oxides (zinc oxide and tin dioxide) used were purchased from Shanghai Titan Technology Co., Ltd.

[0067] The indium tin oxide (ITO) glass (purchased from Shenzhen Huanan Xiangcheng Technology Co., Ltd.) was first cleaned with detergent, then ultrasonically cleaned with deionized water, acetone and isopropanol in sequence, dried and then placed in an ozone cleaner for further processing. The detailed cleaning process will not be described in the following examples.

[0068] The spin coating conditions for the hole transport layer were: 3000 rpm for 30 s. The spin coating conditions for the active layer were: 2600 rpm for 30 s. The spin coating conditions for the electron transport layer were: 3000 rpm for 30 s.

[0069] Example 1 (1) 20 μL of 1.5wt% PEDOT:PSS(Al4083) aqueous solution was spin-coated onto indium tin oxide (ITO) glass and annealed at 150 °C for 20 min to obtain a hole transport layer with a thickness of 25 nm.

[0070] (2) Dissolve 4 mg of PM6 and 5 mg of BTP-eC9 in 0.5 mL of chlorobenzene to obtain a mixed solution, and spin-coat the entire solution onto the hole transport layer. After drying at 100 °C for 5 min, an active layer with a thickness of 70 nm can be obtained.

[0071] (3) Add 5 mg of the organic acid additive shown in formula (1-1) and 15 mg of zinc oxide nanoparticles (average particle size of 5 nm) to 1 mL of n-butanol to obtain an electron transport layer composition solution. Coat the outer surface of the active layer twice, with the volume ratio of the solution being 67% and 33% respectively. After the first coating, anneal at 150 °C for 10 min to obtain a first composition layer with a thickness of 80 nm. After cooling to room temperature, coat the outer surface of the first composition layer with the remaining electron transport layer composition and anneal at 150 °C for 10 min to obtain a second composition layer with a thickness of 40 nm. Finally, obtain an electron transport layer with a thickness of 120 nm.

[0072] (4) The electron transport layer is sputtered on the outer surface by magnetron sputtering (vacuum degree 10). -5 An indium zinc oxide electrode with a thickness of 100 nm was prepared by sputtering at 80 W Pa.

[0073] Organic solar cells are prepared through the above steps.

[0074] The resulting JV curve is as follows Figure 1 As shown. (Through) Figure 1 The open-circuit voltage of the solar cell can be obtained from the JV curve shown. V OC The short-circuit current density is 0.814 V. J SC 18 mA·cm –2 The fill factor (FF) is 68.4% and the photoelectric conversion efficiency (PCE) is 10%.

[0075] Visible light transmittance curve as shown Figure 2 As shown, through Figure 2 The visible light transmittance curve shown indicates that the average visible light transmittance of this solar cell is 51%.

[0076] Example 2 (1) 20 μL of 1.5wt% PEDOT:PSS(Al4083) aqueous solution was spin-coated onto indium tin oxide (ITO) glass and annealed at 150 °C for 20 min to obtain a hole transport layer with a thickness of 25 nm.

[0077] (2) Dissolve 4 mg of PM6 and 5 mg of BTP-eC9 in 0.5 mL of chlorobenzene to obtain a mixed solution, and spin-coat the entire solution onto the hole transport layer. After drying at 100 °C for 5 min, an active layer with a thickness of 70 nm can be obtained.

[0078] (3) Add 4.9 mg of the organic acid additive shown in formula (1-2) and 24.5 mg of tin dioxide nanoparticles (average particle size of 10 nm) to 1.5 mL of n-butanol to obtain an electron transport layer composition solution. Coat the outer surface of the active layer three times, with the volume percentage of the solution being 50%, 34%, and 16% respectively. After the first coating, anneal at 150 °C for 10 min to obtain a first composition layer with a thickness of 60 nm. After cooling to room temperature, coat the outer surface of the first composition layer with 34% of the electron transport layer composition solution. After annealing at 150 °C for 10 min to obtain a second composition layer with a thickness of 40 nm. After cooling to room temperature, coat the outer surface of the second composition layer with 16% of the electron transport layer composition solution. After annealing at 150 °C for 10 min to obtain a third composition layer with a thickness of 20 nm. Finally, an electron transport layer with a thickness of 120 nm is obtained.

[0079] (4) The electron transport layer is sputtered on the outer surface by magnetron sputtering (vacuum degree 10). -5 An indium zinc oxide electrode with a thickness of 100 nm was prepared by sputtering at 80 W Pa.

[0080] Organic solar cells are prepared through the above steps.

[0081] The resulting JV curve is as follows Figure 3 As shown. (Through) Figure 3 The open-circuit voltage of the solar cell can be obtained from the JV curve shown. V OC The short-circuit current density is 0.8 V. J SC It is 17.7 mA·cm –2 The fill factor FF is 68.8% and the photoelectric conversion efficiency PCE is 9.74%.

[0082] Visible light transmittance curve as shown Figure 4 As shown, through Figure 4 The visible light transmittance curve shown indicates that the average visible light transmittance of this solar cell is 50%.

[0083] Example 3 (1) 20 μL of 1.5wt% PEDOT:PSS(Al4083) aqueous solution was spin-coated onto indium tin oxide (ITO) glass and annealed at 150 °C for 20 min to obtain a hole transport layer with a thickness of 25 nm.

[0084] (2) Dissolve 4 mg of PM6 and 5 mg of BTP-eC9 in 0.5 mL of chlorobenzene to obtain a mixed solution, and spin-coat the entire solution onto the hole transport layer. After drying at 100 °C for 5 min, an active layer with a thickness of 70 nm can be obtained.

[0085] (3) 12 mg of the organic acid additive shown in formula (1-3) and 30 mg of zinc oxide nanoparticles (average particle size of 5 nm) were added to 1.7 mL of n-butanol to obtain an electron transport layer composition solution. This solution was then coated onto the outer surface of the active layer in four coats, with the volume percentages of the solution being 45.8%, 30.8%, 19.2%, and 4.2% respectively. After the first coat, the solution was annealed at 150 °C for 10 min to obtain a first composition layer with a thickness of 55 nm. After cooling to room temperature, 30.8% of the electron transport layer composition solution was coated onto the outer surface of the first composition layer, and annealed at 150 °C for 10 min to obtain a second composition layer with a thickness of 37 nm. After cooling to room temperature, 19.2% of the electron transport layer composition solution was coated onto the outer surface of the second composition layer, and annealed at 150 °C for 10 min to obtain a second composition layer with a thickness of 23 nm. After cooling to room temperature, a third composition layer with a thickness of 5 nm is formed. Then, a 4.2% electron transport layer is coated onto the outer surface of the third composition layer with a composition solution. The mixture is then annealed at 150 °C for 10 min to obtain a fourth composition layer with a thickness of 5 nm. Finally, an electron transport layer with a thickness of 120 nm is obtained.

[0086] (4) The electron transport layer is sputtered on the outer surface by magnetron sputtering (vacuum degree 10). -5 An indium zinc oxide electrode with a thickness of 100 nm was prepared by sputtering at 80 W Pa.

[0087] Organic solar cells are prepared through the above steps.

[0088] The resulting JV curve is as follows Figure 5 As shown. (Through) Figure 5 The open-circuit voltage of the solar cell can be obtained from the JV curve shown. V OC The short-circuit current density is 0.799 V. J SC It is 17.5 mA·cm –2The fill factor FF is 69% and the photoelectric conversion efficiency PCE is 9.66%.

[0089] Visible light transmittance curve as shown Figure 6 As shown, through Figure 6 The visible light transmittance curve shown indicates that the average visible light transmittance of this solar cell is 50.7%.

[0090] Example 4 (1) 20 μL of 1.5wt% PEDOT:PSS(Al4083) aqueous solution was spin-coated onto indium tin oxide (ITO) glass and annealed at 150 °C for 20 min to obtain a hole transport layer with a thickness of 25 nm.

[0091] (2) Dissolve 4 mg of PM6 and 5 mg of BTP-eC9 in 0.5 mL of chlorobenzene to obtain a mixed solution, and spin-coat the entire solution onto the hole transport layer. After drying at 100 °C for 5 min, an active layer with a thickness of 70 nm can be obtained.

[0092] (3) 5.4 mg of the organic acid additive shown in formula (2-1) and 18 mg of zinc oxide nanoparticles (average particle size of 8 nm) were added to 1 mL of n-butanol to obtain an electron transport layer composition solution. The solution was coated on the outer surface of the active layer in two coats, with the volume percentage of the solution being 67% and 33% respectively. After the first coating, the solution was annealed at 150 °C for 10 min to obtain a first composition layer with a thickness of 80 nm. After cooling to room temperature, the remaining electron transport layer composition was coated on the outer surface of the first composition layer and annealed at 150 °C for 10 min to obtain a second composition layer with a thickness of 40 nm. Finally, an electron transport layer with a thickness of 120 nm was obtained.

[0093] (4) The electron transport layer is sputtered on the outer surface by magnetron sputtering (vacuum degree 10). -5 An indium zinc oxide electrode with a thickness of 100 nm was prepared by sputtering at 80 W Pa.

[0094] Organic solar cells are prepared through the above steps.

[0095] The resulting JV curve is as follows Figure 7 As shown. (Through) Figure 7 The open-circuit voltage of the solar cell can be obtained from the JV curve shown. V OC The short-circuit current density is 0.815 V. J SC 18 mA·cm –2The fill factor FF is 68% and the photoelectric conversion efficiency PCE is 9.95%.

[0096] Visible light transmittance curve as shown Figure 8 As shown, through Figure 8 The visible light transmittance curve shown indicates that the average visible light transmittance of this solar cell is 50.4%.

[0097] Example 5 According to the method of Example 1, the difference is that in step (3), the amount of organic acid additive shown in formula (1-1) is 1 mg and the amount of zinc oxide nanoparticles is 20 mg, so that the weight ratio of the metal oxide shown to the organic acid additive of formula (1-1) is 1:0.05, and finally an organic solar cell is obtained.

[0098] Open circuit voltage of solar cells V OC The short-circuit current density is 0.808 V. J SC It is 16.4 mA·cm –2 The fill factor FF is 69.7%, the photoelectric conversion efficiency is 9.24%, and the average visible light transmittance is 49.3%.

[0099] Example 6 According to the method of Example 1, the difference is that in step (3), the amount of organic acid additive shown in formula (1-1) is 10 mg and the amount of zinc oxide nanoparticles is 10 mg, so that the weight ratio of the metal oxide shown to the organic acid additive in formula (1-1) is 1:1, and finally an organic solar cell is obtained.

[0100] Open circuit voltage of solar cells V OC The short-circuit current density is 0.806 V. J SC It is 16.3 mA·cm –2 The fill factor (FF) is 69.2%, the photoelectric conversion efficiency (PCE) is 9.09%, and the average visible light transmittance is 48.6%.

[0101] Example 7 According to the method of Example 1, the difference is that in step (3), the electron transport layer is coated on the outer surface of the active layer with the composition solution in one step, and the remaining steps are the same as in Example 1, and finally an organic solar cell is obtained.

[0102] Open circuit voltage of solar cells V OC The short-circuit current density is 0.677 V. J SCIt is 17.1 mA·cm –2 The fill factor (FF) is 45.5%, the photoelectric conversion efficiency (PCE) is 5.27%, and the average visible light transmittance is 54.9%.

[0103] Example 8 The method of Example 1 is different in that, in step (3), the electron transport layer is coated on the outer surface of the active layer with the composition solution in five coats, and the volume percentage of the solution in each coat is 43.3%, 28.3%, 14.2%, 7.1% and 7.1% respectively. The remaining steps are the same as in Example 1, and an organic solar cell is finally obtained.

[0104] The thickness of the first composition layer is 52 nm, the thickness of the second composition layer is 34 nm, the thickness of the third composition layer is 17 nm, the thickness of the fourth composition layer is 8.5 nm, and the thickness of the fifth composition layer is 8.5 nm.

[0105] Open circuit voltage of solar cells V OC The short-circuit current density is 0.765 V. J SC It is 18.2 mA·cm –2 The fill factor (FF) is 67.6%, the photoelectric conversion efficiency (PCE) is 9.41%, and the average visible light transmittance is 45%.

[0106] Example 9 According to the method of Example 1, the difference is that in step (3), the organic acid additive shown in formula (1-1) is replaced with the organic acid additive shown in formula (1-6), and finally an organic solar cell is obtained.

[0107] Open circuit voltage of solar cells V OC The short-circuit current density is 0.742 V. J SC It is 16.8 mA·cm –2 The fill factor (FF) is 50.5%, the photoelectric conversion efficiency (PCE) is 6.3%, and the average visible light transmittance is 48.8%.

[0108] Example 10 According to the method of Example 1, the difference is that in step (3), the organic acid additive shown in formula (1-1) is replaced with the organic acid additive shown in formula (2-6), and finally an organic solar cell is obtained.

[0109] Open circuit voltage of solar cells V OC The short-circuit current density is 0.741 V. JSC 16.8 mA cm –2 The fill factor (FF) is 51.2%, the photoelectric conversion efficiency (PCE) is 6.37%, and the average visible light transmittance is 48.5%.

[0110] Comparative Example 1 The method of Example 1 is different except that in step (3), the composition for the electron transport layer does not contain organic acid additives, and the remaining steps are the same as in Example 1, and finally an organic solar cell is obtained.

[0111] The resulting JV curve is as follows Figure 9 As shown. (Through) Figure 9 The open-circuit voltage of the solar cell can be obtained from the JV curve shown. V OC The short-circuit current density is 0.298 V. J SC 17.4 mA cm –2 The fill factor FF is 25% and the photoelectric conversion efficiency PCE is 1.3%.

[0112] Visible light transmittance curve as shown Figure 10 As shown, through Figure 10 The visible light transmittance curve shown indicates that the average visible light transmittance of this solar cell is 44.5%.

[0113] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composition for an electron transport layer, characterized in that, The composition contains a metal oxide and an organic acid additive, wherein the organic acid additive is selected from one or more compounds of formula (1) or formula (2): Equation (1) Equation (2) ; Wherein, R1 is selected from one or more of the following: a linking bond, a C1-C12 alkylene group, and a C2-C12 alkenyl group; each R2 is independently selected from one or more of H and a C1-C12 alkyl group; R3 and R4 are independently selected from one or more of H and a C1-C12 alkoxy group; R5 is selected from one or more of hydroxyl groups or hydroxyl-containing groups, or R5 is cyclized with R3 or R4 to form an oxygen-containing heterocycle; R6 is selected from one or more of the following: a linking bond, a C1-C12 alkylene group, and a C2-C12 alkenyl group; and n is an integer from 1 to 8.

2. The composition for an electron transport layer according to claim 1, wherein, R1 is selected from one or more of the following: a linking bond, a C1-C6 alkylene group, and a C2-C6 alkenyl group; each R2 is independently selected from one or more of H and C1-C6 alkyl groups; R3 and R4 are independently selected from one or more of H and C1-C6 alkoxy groups; R5 is selected from one or more of hydroxyl and C1-C6 hydroxyalkyl groups, or R5 is cyclized with R3 or R4 to form... Bond; R6 is selected from one or more of the following: linking bond, C1-C6 alkylene group, and C2-C6 alkenyl group; n is an integer from 1 to 6; Preferably, R1 is selected from one or more of the following: a linking bond, a C1-C3 alkylene group, and a C2-C4 alkenyl group; each R2 is independently selected from one or more of H and C1-C3 alkyl groups; R3 and R4 are each independently selected from one or more of H and C1-C3 alkoxy groups; R5 is selected from one or more of hydroxyl and C1-C3 hydroxyalkyl groups, or R5 is cyclized with R3 or R4 to form... Bond; R6 is selected from one or more of the following: linking bond, C1-C3 alkylene group, and C2-C4 alkenyl group; n is an integer from 2 to 4; More preferably, R1 is selected from one or more of the following: a linking bond, -CH2-, -CH2CH2-, -CH=CH-, -CH=CH-CH2-, and -CH=CH-CH2-CH2-; each R2 is independently selected from one or more of H, -CH3, -CH2CH3, and -CH2CH2CH3; R3 and R4 are independently selected from one or more of H, -OCH3, -OCH2CH3, and -OCH2CH2CH3; R5 is selected from one or more of -OH, -CH2OH, -CH2CH2OH, and -CH2CH2CH2OH, or R5 is cyclic with R3 or R4 to form The key; R6 is selected from one or more of the following: linker, -CH2-, -CH2CH2-, -CH=CH-, and -CH=CH-CH2-; n is 2 or 3.

3. The composition for an electron transport layer according to claim 1 or 2, wherein, The compound represented by formula (1) is selected from one or more of the compounds represented by the following formulas: ； And / or, the compound represented by formula (2) is selected from one or more of the compounds represented by the following formulas: 。 4. The composition for an electron transport layer according to any one of claims 1-3, wherein, The weight ratio of the metal oxide to the organic acid additive is 1: 0.05-1, preferably 1:0.2-0.4; And / or, the metal oxide is selected from one or more of ZnO, TiO2 and SnO2, preferably ZnO and / or SnO2; And / or, the average particle size of the metal oxide is 3-20 nm, preferably 5-10 nm.

5. An organic solar cell device, characterized in that, The organic solar cell device includes an electron transport layer, the electron transport layer comprising at least one composition layer, the composition layer comprising the composition for an electron transport layer as described in any one of claims 1-4.

6. The organic solar cell device according to claim 5, wherein, The organic solar cell device includes, from bottom to top, a conductive substrate, a hole transport layer, an active layer, an electron transport layer, and a transparent top electrode.

7. The organic solar cell device according to claim 5 or 6, wherein, The thickness of the electron transport layer is 55-125 nm, preferably 60-120 nm; And / or, the thickness of the composition layer is 1-125 nm, preferably 5-120 nm; And / or, the number of layers in the composition is 1-5, preferably 2-4.

8. A method for fabricating the organic solar cell device according to any one of claims 5-7, wherein, The method includes: applying an electron transport layer composition to the surface of an active layer to obtain at least one composition layer.

9. The preparation method according to claim 8, wherein, A method for applying the electron transport layer composition to the surface of the active layer includes: coating a solution of the electron transport layer composition onto the surface to be coated and annealing it to obtain the composition layer; And / or, the concentration of the metal oxide in the solution of the composition for the electron transport layer is 10-20 mg / mL, preferably 15-18 mg / mL; And / or, the concentration of the organic acid additive in the solution of the composition for the electron transport layer is 1-10 mg / mL, preferably 3-7.5 mg / mL; And / or, the annealing conditions include: a temperature of 140-180 °C and a time of 8-25 min; more preferably, the annealing conditions include: a temperature of 150-170 °C and a time of 10-20 min.

10. The method according to claim 8 or 9, wherein, The method further includes: forming a hole transport layer on a conductive substrate, forming an active layer on the outer surface of the hole transport layer, forming an electron transport layer on the outer surface of the active layer, and forming a transparent top electrode on the outer surface of the electron transport layer; Preferably, the transparent top electrode is fabricated by magnetron sputtering.

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