Organic solar cell based on in-situ crosslinking self-assembly monomolecular layer and preparation method thereof
By using a self-assembled monolayer cross-linked in situ with formaldehyde dimethyl acetal as a hole transport layer in organic solar cells, the problems of performance degradation and weak interfacial bonding under harsh environments were solved, achieving a highly efficient photoelectric conversion effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIAXING RES INST ZHEJIANG UNIV
- Filing Date
- 2025-11-14
- Publication Date
- 2026-04-10
AI Technical Summary
Existing self-assembled monolayer materials are prone to degradation under high temperature, strong light and high humidity conditions, leading to performance degradation. Furthermore, they have weak bonding with adjacent interfaces and are prone to microscopic peeling or side reactions, which affect device performance.
A self-assembled monolayer cross-linked in situ with formaldehyde dimethyl acetal was used as a hole transport layer. A tight hole transport layer was formed by spin coating and annealing, which enhanced the bonding between molecules and the interfacial binding force, and inhibited the breaking of chemical bonds and the formation of voids.
It significantly improves the photoelectric conversion efficiency of organic solar cells, enhances the robustness and interface stability of materials, and slows down device performance degradation.
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Figure CN121843340A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic solar cells, and more specifically, discloses an organic solar cell based on an in-situ cross-linked self-assembled monolayer and its preparation method. Background Technology
[0002] Organic solar cells have shown broad development prospects in the field of new energy due to their advantages such as low cost, light weight, adjustable structure and function, and large-area flexible fabrication, and have become one of the important development directions.
[0003] Among various battery performance enhancement technologies, using self-assembled monolayers as hole transport layers demonstrates significant advantages. This technology, through precise control of energy level structure, can effectively extract photogenerated holes and passivate interface defects, thereby significantly improving charge transport efficiency. The optimized monolayer exhibits excellent adhesion stability under harsh conditions such as high temperature and humidity variations, and is not easily detached. Furthermore, this technology can achieve efficient fabrication of large-area devices using solution spin coating, is highly compatible with existing photovoltaic production lines, and effectively overcomes the problems of high cost and poor uniformity associated with traditional vacuum evaporation processes.
[0004] The existing technology has the following technical problems:
[0005] 1) Most self-assembled monolayer materials are composed of organic molecules, and their chemical bonds are prone to degradation, oxidation or even breakage under long-term high temperature, strong light (especially ultraviolet light) or high humidity, which leads to the degradation of the material's performance.
[0006] 2) During the self-assembly process, self-assembled monolayer materials may aggregate unevenly, resulting in partial exposure of the substrate surface, forming voids, and causing charge recombination at the device level.
[0007] 3) The bonding force between ultrathin self-assembled monolayers and adjacent interfaces is weak, posing a critical problem of insufficient mechanical and chemical stability. During device packaging or long-term operation, microscopic delamination or side reactions can easily occur at the interface, which may eventually lead to device performance degradation or failure. Summary of the Invention
[0008] To address the shortcomings of existing technologies, this invention provides an organic solar cell based on an in-situ cross-linked self-assembled monolayer and its fabrication method. The method of this invention, which optimizes the hole transport layer for fabricating organic solar cells, significantly improves the photoelectric conversion efficiency of organic solar cells. This invention is achieved through the following technical solutions:
[0009] This invention discloses an organic solar cell based on an in-situ cross-linked self-assembled monolayer. The cell structure consists of, from bottom to top, an anode substrate, a hole transport layer, an active layer, an electron transport layer, and a metal cathode.
[0010] As a further improvement, the anode substrate of the present invention is indium tin oxide glass (ITO); the hole transport layer is a self-assembled monolayer cross-linked in situ by an acetal cross-linking agent; the active layer is a mixture of any electron donor and electron acceptor; the electron transport layer is PDINN; and the cathode layer is Ag.
[0011] This invention also discloses a method for preparing organic solar cells based on in-situ cross-linked self-assembled monolayers, the specific steps of which are as follows:
[0012] Step 1: Clean the anode substrate. First, use detergent, deionized water, acetone and isopropanol respectively to ultrasonically clean for 10-15 minutes each; then use a dry nitrogen stream to dry the anode substrate.
[0013] Step 2: Spin-coat a hole transport layer onto the anode substrate cleaned in Step 1; prepare a hole transport layer solution by dissolving the self-assembled monolayer in an alcohol solvent; prepare a crosslinking agent solution by dissolving the acetal crosslinking agent in an alcohol solvent; spin-coat the hole transport layer solution onto the anode substrate at a speed of 2000-5000 rpm for 40-60 s; spin-coat the crosslinking agent solution onto the hole transport layer for in-situ crosslinking at a speed of 2000-5000 rpm for 40-60 s; anneal the crosslinked hole transport layer at a temperature of 60-150℃ for 5-15 min.
[0014] Step 3: Spin-coat the active layer solution onto the hole transport layer obtained in Step 2. The active layer solution is prepared from a PM6:L8-BO mixed solution. The PM6:L8-BO active layer is prepared by mixing PM6 and L8-BO at a mass ratio of 1:1-1.5 and dissolving them in a mixed solvent composed of chloroform and 1,8-diiodooctane to prepare an active layer solution with a concentration of 16-20 mg / mL. The solution is stirred at room temperature for 3-5 hours, and the volume percentage of 1,8-diiodooctane is 0.1-0.5%. The active layer solution is then spin-coated at a speed of 2000-3000 rpm, an annealing temperature of 60-150℃, an annealing time of 5-15 minutes, and an active layer thickness of 100-150 nm.
[0015] Step 4: Spin-coat the electron transport layer onto the active layer obtained in Step 3; dissolve PDINN in an alcohol solvent to prepare an electron transport layer solution; spin-coat the electron transport layer solution at a speed of 2000-5000 rpm for 30-50 seconds.
[0016] Step 5: Deposit a cathode layer onto the electron transport layer obtained in step 4, reducing the vacuum level to 5 × 10⁻⁶. -4 Below Pa, The metal Ag was deposited at a rate of 80-120 nm as the top electrode.
[0017] As a further improvement, the acetal crosslinking agent described in this invention is any one of formaldehyde dimethyl acetal, formaldehyde diethanol, acetaldehyde dimethyl acetal, acetaldehyde diethanol, and benzaldehyde dimethyl acetal.
[0018] As a further improvement, the acetal crosslinking agent described in this invention is formaldehyde dimethyl acetal.
[0019] As a further improvement, the self-assembled monolayer in step two of this invention is any one of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(9H-carbazole-9-yl)butyl)phosphonic acid, (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, and (2-(7H-dibenzocarbazole-7-yl)ethyl)phosphonic acid.
[0020] As a further improvement, the alcohol solvent in step two of the present invention is any one of methanol, ethanol, isopropanol, and 2-methoxyethanol.
[0021] As a further improvement, the method for preparing the crosslinking agent solution in step two of the present invention is to select a ratio of 0.2-5 between the amount of formaldehyde dimethyl acetal and the amount of self-assembled monolayer material.
[0022] The beneficial effects of this invention are as follows:
[0023] This invention discloses an organic solar cell based on an in-situ cross-linked self-assembled monolayer and its preparation method. This invention uses a formaldehyde dimethyl ether in-situ cross-linked self-assembled monolayer as a hole transport layer, replacing the traditional single self-assembled monolayer, to prepare a high-efficiency organic solar cell.
[0024] This invention selects a self-assembled monolayer of formaldehyde dimethyl acetal crosslinked in situ as a hole transport layer. The advantage of this is that it can increase the number of bonds between self-assembled molecules and reduce the chemical bond breakage that occurs under external stress, thereby affecting the material properties.
[0025] This invention selects a self-assembled monolayer of formaldehyde dimethyl acetal in situ crosslinked as the hole transport layer. The advantage of this is that it can form a dense hole transport layer, improve the uniformity of the distribution of the transport layer material on the substrate surface, and suppress the formation of voids.
[0026] The present invention selects a self-assembled monolayer with in-situ crosslinking of formaldehyde dimethyl acetal as a hole transport layer. The advantage of this is that it can improve the binding force between the self-assembled molecules and the adjacent interface, suppress the interface peeling or side reaction caused by external stress, and slow down the performance degradation of the device.
[0027] The present invention selects a commonly used alcohol solvent as the solvent to dissolve formaldehyde dimethyl acetal and self-assembled monolayer materials. The advantage of this is that it ensures that a small amount of dissolution occurs at the hole transport layer interface, improves the degree of cross-linking polymerization of interface molecules, and enhances the cross-linking effect of the hole transport layer.
[0028] The present invention selects a ratio of formaldehyde dimethyl ether to self-assembled monolayer material of 0.2-5, which has the advantage of increasing robustness and reducing the impact of weighing errors on device performance.
[0029] Using the self-assembled monolayer of formaldehyde dimethyl acetal in situ crosslinked as the hole transport layer in this invention can significantly improve the photoelectric conversion efficiency of organic solar cells. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of an organic solar cell structure.
[0031] Figure 2 JV curve for organic solar cells prepared in Application Example 1;
[0032] Figure 3 JV curve for organic solar cells prepared in Application Example 2;
[0033] Figure 4 JV curve for organic solar cells prepared in Application Example 3;
[0034] Figure 5 JV curve for organic solar cells prepared in Application Example 4. Detailed Implementation
[0035] This invention provides an organic solar cell based on an in-situ cross-linked self-assembled monolayer. For example... Figure 1 As shown, the battery structure consists of, from bottom to top, an anode substrate, a hole transport layer, an active layer, an electron transport layer, and a cathode layer. The anode substrate is indium tin oxide glass (ITO); the hole transport layer is a self-assembled monolayer cross-linked in situ by an acetal cross-linking agent; the active layer is a mixture of arbitrary electron donors and electron acceptors; the electron transport layer is PDINN; and the cathode layer is Ag.
[0036] The above-mentioned method for preparing organic solar cells based on in-situ cross-linked self-assembled monolayers includes the following steps:
[0037] Step 1: Clean the anode substrate;
[0038] The anode substrate cleaning method in step one is as follows: First, use detergent, deionized water, acetone and isopropanol respectively to ultrasonically clean for 10-15 minutes each; then use a dry nitrogen gas flow to dry the anode substrate.
[0039] Step 2: Spin-coat the hole transport layer onto the anode substrate that has been cleaned in Step 1.
[0040] Step 2, the hole transport layer preparation method, is as follows: The self-assembled monolayer 2PACz is dissolved in ethanol to prepare a hole transport layer solution; formaldehyde dimethyl acetal is dissolved in ethanol to prepare a crosslinking agent solution; the hole transport layer solution is spin-coated onto the anode substrate at a speed of 2000-5000 rpm for 40-60 s; the crosslinking agent solution is spin-coated onto the hole transport layer for in-situ crosslinking at a speed of 2000-5000 rpm for 40-60 s; the crosslinked hole transport layer is then annealed at a temperature of 60-150℃ for 5-15 min.
[0041] Step 3: Spin-coat the active layer solution onto the hole transport layer obtained in step 2. The active layer solution is prepared from a PM6:L8-BO mixed solution.
[0042] Step 3: The preparation method of PM6:L8-BO active layer is as follows: PM6 and L8-BO are mixed at a mass ratio of 1:1-1.5 and dissolved in a mixed solvent composed of chloroform and 1,8-diiodooctane to prepare an active layer solution with a concentration of 16-20 mg / mL. The solution is stirred at room temperature for 3-5 hours, and the volume percentage of 1,8-diiodooctane is 0.1-0.5%. The active layer solution is then spin-coated onto the substrate obtained in Step 2 at a speed of 2000-3000 rpm, an annealing temperature of 60-150℃, an annealing time of 5-15 minutes, and an active layer thickness of 100-150 nm.
[0043] Step four: Spin-coat the electron transport layer onto the substrate obtained in step three.
[0044] Step four involves the preparation of the electron transport layer as follows: PDINN is dissolved in an alcohol solvent to prepare an electron transport layer solution; the electron transport layer solution is then spin-coated onto the substrate obtained in step three at a speed of 2000-5000 rpm for 30-50 seconds.
[0045] Step 5: Evaporate a cathode layer onto the substrate obtained in step 4.
[0046] Step 5, the cathode layer preparation method is as follows: the vacuum degree is reduced to 5×10 -4 Below Pa, The metal Ag was deposited at a rate of 80-120 nm as the top electrode.
[0047] After the above steps are completed, an organic solar cell based on an in-situ cross-linked self-assembled monolayer is obtained. The superior performance embodiments of the present invention are further described in detail below with reference to the accompanying drawings.
[0048] Example 1.
[0049] Weigh 0.35 mg of 2PACz into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the 2PACz solution onto an ITO conductive glass substrate at 5000 rpm for 40 s. Weigh 0.02 mg of formaldehyde dimethyl acetal into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the formaldehyde dimethyl acetal solution onto a 2PACz substrate at 5000 rpm for 40 s, and anneal at 100 °C for 10 min to prepare a hole transport layer film, labeled HTL-1.
[0050] Example 2.
[0051] Weigh 0.35 mg of 2PACz into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the 2PACz solution onto an ITO conductive glass substrate at 5000 rpm for 40 s. Weigh 0.1 mg of formaldehyde dimethyl acetal into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the formaldehyde dimethyl acetal solution onto a 2PACz substrate at 5000 rpm for 40 s, and anneal at 100 °C for 10 min to prepare a hole transport layer film, labeled HTL-2.
[0052] Example 3.
[0053] Weigh 0.35 mg of 2PACz into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the 2PACz solution onto an ITO conductive glass substrate at 5000 rpm for 40 s. Weigh 0.5 mg of formaldehyde dimethyl acetal into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the formaldehyde dimethyl acetal solution onto a 2PACz substrate at 5000 rpm for 40 s, and anneal at 100 °C for 10 min to prepare a hole transport layer film, labeled HTL-3.
[0054] Comparative Example 1.
[0055] Weigh 0.35 mg of 2PACz into a glass sample vial, add 1 mL of ethanol solvent, and stir at room temperature until homogeneous. Spin-coat the 2PACz solution onto ITO conductive glass at 5000 rpm for 40 s, and anneal at 100 °C for 10 min to prepare a hole transport layer film, labeled HTL-4.
[0056] Application example 1.
[0057] In Application Example 1, an organic solar cell was fabricated using the hole transport layer obtained in Example 1, with the structure: ITO / HTL-1 / PM6:L8-BO / PDINN / Ag. PM6 and L8-BO were mixed at a mass ratio of 1:1.2 and dissolved in a mixed solvent of chloroform and 1,8-diiodooctane (99.5:0.5) to prepare an active layer solution with a concentration of 17.6 mg / mL. The active layer solution was spin-coated onto the hole transport layer at 2400 rpm and annealed at 100°C for 10 min. 1 mg of PDINN was dissolved in 1 mL of methanol to prepare an electron transport layer solution, which was then spin-coated onto the active layer at 3000 rpm. The substrate was then transferred to a vacuum evaporation chamber, and the vacuum level was allowed to drop to 5 × 10⁻⁶. -4 Below Pa, The top electrode was prepared by evaporating 80 nm of Ag metal at a high rate. The resulting organic solar cell was labeled OSC-1.
[0058] At AM1.5G 100mW / cm 2 Under the illumination conditions, the JV performance curves of all prepared organic solar cell devices were tested, and the results are as follows: Figure 2 As shown.
[0059] The performance parameters of the organic solar cell OSC-1 are: open-circuit voltage 0.863V, short-circuit current density 25.20mA / cm². 2 The fill factor is 78.64%, and the photoelectric conversion efficiency is 17.09%.
[0060] Application Example 2.
[0061] In Application Example 2, an organic solar cell was fabricated using the hole transport layer obtained in Example 2, with the structure: ITO / HTL-2 / PM6:L8-BO / PDINN / Ag. PM6 and L8-BO were mixed at a mass ratio of 1:1.2 and dissolved in a mixed solvent of chloroform and 1,8-diiodooctane (99.5:0.5) to prepare an active layer solution with a concentration of 17.6 mg / mL. The active layer solution was spin-coated onto the hole transport layer at 2400 rpm and annealed at 100°C for 10 min. 1 mg of PDINN was dissolved in 1 mL of methanol to prepare an electron transport layer solution, which was then spin-coated onto the active layer at 3000 rpm. The substrate was then transferred to a vacuum evaporation chamber, and the vacuum level was allowed to drop to 5 × 10⁻⁶. -4 Below Pa, The top electrode was prepared by evaporating 80 nm of Ag metal at a specific rate. The resulting organic solar cell was labeled OSC-2.
[0062] At AM1.5G 100mW / cm 2Under the illumination conditions, the JV performance curves of all prepared organic solar cell devices were tested, and the results are as follows: Figure 3 As shown.
[0063] The performance parameters of the organic solar cell OSC-2 are: open-circuit voltage 0.872V, short-circuit current density 26.38mA / cm². 2 The fill factor is 78.63%, and the photoelectric conversion efficiency is 18.08%.
[0064] Application example 3.
[0065] In Application Example 3, an organic solar cell was fabricated using the hole transport layer obtained in Example 3, with the structure: ITO / HTL-3 / PM6:L8-BO / PDINN / Ag. PM6 and L8-BO were mixed at a mass ratio of 1:1.2 and dissolved in a mixed solvent of chloroform and 1,8-diiodooctane (99.5:0.5) to prepare an active layer solution with a concentration of 17.6 mg / mL. The active layer solution was spin-coated onto the hole transport layer at 2400 rpm and annealed at 100°C for 10 min. 1 mg of PDINN was dissolved in 1 mL of methanol to prepare an electron transport layer solution, which was then spin-coated onto the active layer at 3000 rpm. The substrate was then transferred to a vacuum evaporation chamber, and the vacuum level was allowed to drop to 5 × 10⁻⁶. -4 Below Pa, The top electrode was prepared by evaporating 80 nm of Ag metal at a high rate. The resulting organic solar cell was labeled OSC-3.
[0066] At AM1.5G 100mW / cm 2 Under the illumination conditions, the JV performance curves of all prepared organic solar cell devices were tested, and the results are as follows: Figure 4 As shown.
[0067] The performance parameters of the organic solar cell OSC-3 are: open-circuit voltage 0.863V, short-circuit current density 24.30mA / cm². 2 The fill factor is 79.60%, and the photoelectric conversion efficiency is 16.69%.
[0068] Application example 4.
[0069] In Application Example 4, an organic solar cell was fabricated using the hole transport layer obtained in Comparative Example 1, with the structure: ITO / HTL-4 / PM6:L8-BO / PDINN / Ag. PM6 and L8-BO were mixed at a mass ratio of 1:1.2 and dissolved in a mixed solvent of chloroform and 1,8-diiodooctane (99.5:0.5) to prepare an active layer solution with a concentration of 17.6 mg / mL. The active layer solution was spin-coated onto the hole transport layer at 2400 rpm and annealed at 100°C for 10 min. 1 mg of PDINN was dissolved in 1 mL of methanol to prepare an electron transport layer solution, which was then spin-coated onto the active layer at 3000 rpm. The substrate was then transferred to a vacuum evaporation chamber, and the vacuum level was allowed to drop to 5 × 10⁻⁶. -4 Below Pa, The top electrode was prepared by evaporating 80 nm of Ag metal at a specific rate. The resulting organic solar cell was labeled OSC-4.
[0070] At AM1.5G 100mW / cm 2 Under the illumination conditions, the JV performance curves of all prepared organic solar cell devices were tested, and the results are as follows: Figure 5 As shown.
[0071] The performance parameters of the organic solar cell OSC-4 are: open-circuit voltage 0.863V, short-circuit current density 24.98mA / cm². 2 The fill factor is 79.07%, and the photoelectric conversion efficiency is 17.04%.
[0072] Compared with the organic solar cell OSC-4 prepared with hole transport layer HTL-4 in Comparative Example 1, the organic solar cell OSC-2 prepared with hole transport layer HTL-2 in Example 2 showed significant improvements in open-circuit voltage and short-circuit current density, especially in photoelectric conversion efficiency, which was improved by more than 6.1%.
[0073] The above embodiments are merely illustrative of several specific implementations of the present invention and should not be construed as limiting the scope of the present invention. Any modifications, substitutions, and improvements made by those skilled in the art without departing from the design and concept of the present invention should be included within the scope of protection of the present invention.
Claims
1. An organic solar cell based on an in-situ cross-linked self-assembled monolayer, characterized in that, The battery structure consists of, from bottom to top, an anode substrate, a hole transport layer, an active layer, an electron transport layer, and a metal cathode.
2. The organic solar cell based on in-situ cross-linked self-assembled monolayer according to claim 1, characterized in that, The anode substrate is indium tin oxide glass (ITO); the hole transport layer is a self-assembled monolayer cross-linked in situ by an acetal cross-linking agent; the active layer is a mixture of any electron donor and electron acceptor; the electron transport layer is PDINN; and the cathode layer is Ag.
3. A method for preparing an organic solar cell based on an in-situ cross-linked self-assembled monolayer as described in claim 1 or 2, characterized in that, The steps are as follows; Step 1: Clean the anode substrate. First, use detergent, deionized water, acetone and isopropanol respectively to ultrasonically clean for 10-15 minutes each; then use a dry nitrogen stream to dry the anode substrate. Step 2: Spin-coat a hole transport layer onto the anode substrate cleaned in Step 1; prepare a hole transport layer solution by dissolving the self-assembled monolayer in an alcohol solvent; prepare a crosslinking agent solution by dissolving the acetal crosslinking agent in an alcohol solvent; spin-coat the hole transport layer solution onto the anode substrate at a speed of 2000-5000 rpm for 40-60 seconds. The crosslinking agent solution was spin-coated onto the hole transport layer for in-situ crosslinking at a speed of 2000-5000 rpm for 40-60 seconds. The crosslinked hole transport layer was then annealed at a temperature of 60-150℃ for 5-15 minutes. Step 3: Spin-coat the active layer solution onto the hole transport layer obtained in Step 2. The active layer solution is prepared from a PM6:L8-BO mixed solution. The PM6:L8-BO active layer is prepared by mixing PM6 and L8-BO at a mass ratio of 1:1-1.5 and dissolving them in a mixed solvent composed of chloroform and 1,8-diiodooctane to prepare an active layer solution with a concentration of 16-20 mg / mL. The solution is stirred at room temperature for 3-5 hours, and the volume percentage of 1,8-diiodooctane is 0.1-0.5%. The active layer solution is then spin-coated at a speed of 2000-3000 rpm, an annealing temperature of 60-150℃, an annealing time of 5-15 minutes, and an active layer thickness of 100-150 nm. Step 4: Spin-coat the electron transport layer onto the active layer obtained in Step 3; dissolve PDINN in an alcohol solvent to prepare an electron transport layer solution; spin-coat the electron transport layer solution at a speed of 2000-5000 rpm for 30-50 seconds. Step 5: Deposit a cathode layer onto the electron transport layer obtained in step 4, reducing the vacuum level to 5 × 10⁻⁶. -4 Below Pa, The metal Ag was deposited at a rate of 80-120 nm as the top electrode.
4. The organic solar cell based on in-situ cross-linked self-assembled monolayer according to claim 3, characterized in that, The acetal crosslinking agent is any one of formaldehyde dimethyl acetal, formaldehyde diethanol, acetaldehyde dimethyl acetal, and benzaldehyde dimethyl acetal.
5. The method for preparing an organic solar cell based on an in-situ cross-linked self-assembled monolayer according to claim 4, characterized in that, The acetal crosslinking agent is formaldehyde dimethyl acetal.
6. The method for preparing an organic solar cell based on an in-situ cross-linked self-assembled monolayer according to claim 4 or 5, characterized in that, The self-assembled monolayer in step two is any one of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(9H-carbazole-9-yl)butyl)phosphonic acid, (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, and (2-(7H-dibenzocarbazole-7-yl)ethyl)phosphonic acid.
7. The method for preparing an organic solar cell based on an in-situ cross-linked self-assembled monolayer according to claim 6, characterized in that, The alcohol solvent in step two is any one of methanol, ethanol, isopropanol, and 2-methoxyethanol.
8. The method for preparing an organic solar cell based on an in-situ cross-linked self-assembled monolayer according to claim 4, 5, or 7, characterized in that, The method for preparing the crosslinking agent solution in step two is to select a ratio of 0.2-5 between the amount of formaldehyde dimethyl acetal and the amount of self-assembled monolayer material.