Organic photovoltaic cell, preparation method and application of conjugated organic frame structure material
By introducing conjugated organic framework materials into organic photovoltaic cells and mixing them with electron donors and acceptors to form an ordered framework structure, the efficiency and stability problems of organic photovoltaic cells are solved, and the short-circuit current and photoelectric conversion efficiency are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-17
- Publication Date
- 2026-04-10
AI Technical Summary
The low photoelectric conversion efficiency and insufficient stability of existing organic photovoltaic cells limit their commercialization and application potential.
Organic photovoltaic cells are prepared by using conjugated organic framework materials as components of the photoactive layer, mixing them with electron donors and acceptors in a specific ratio, and then preparing them through spin coating and evaporation deposition processes. This process forms an active layer with an ordered framework structure and pores, thereby improving exciton separation and transport efficiency.
This improved the short-circuit current and photoelectric conversion efficiency of organic photovoltaic cells, enhanced the stability of the active layer, promoted exciton separation and transport, and improved the overall performance of the device.
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Figure CN121843409A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optoelectronic materials technology, and in particular to organic photovoltaic cells and their preparation methods and the application of conjugated organic framework structure materials. Background Technology
[0002] Organic photovoltaic cells (OSCs) are devices that convert light energy into electrical energy. Among them, bulk heterojunction (BHJ) cells have achieved efficiency exceeding 20% thanks to researchers' efforts, but there is still a gap compared to silicon-based and perovskite photovoltaic cells. Meanwhile, the stability of these cells is receiving increasing attention.
[0003] Numerous studies have shown that the degradation of the active layer under photothermal conditions is most strongly correlated with device decay, a phenomenon determined by the bulk heterojunction structure. The active layer typically comprises multiple phases, such as donor, acceptor, and donor-acceptor mixtures. The dissociation of photogenerated carriers requires a homogeneous amorphous phase to provide sufficient donor / acceptor (D / A) interfaces, and the transport of the generated free carriers (with a maximum diffusion distance of only 20 nm) within the crystalline phase to form a photocurrent. Any physical process leading to a reduction in D / A interfaces and excessive phase separation size will adversely affect the photocurrent, resulting in a sharp decline in exciton separation and charge transport efficiency. Because organic materials have relatively low glass transition temperatures, their blended morphologies are often in a metastable state, and decay tends to transition from the initial thermodynamic metastable state to a thermodynamic equilibrium state. The photoelectric conversion efficiency and active layer stability of the device significantly limit its commercialization and potential applications. Summary of the Invention
[0004] This application provides an organic photovoltaic cell, its preparation method, and the application of conjugated organic framework structure materials, aiming to solve the technical problem of low photoelectric conversion efficiency in existing photovoltaic cells.
[0005] To address the aforementioned technical problems, embodiments of this application provide: an organic photovoltaic cell, comprising: an ITO substrate, a photoactive layer, and a metal electrode;
[0006] The photoactive layer is composed of a conjugated organic framework material, an electron donor, and an electron acceptor.
[0007] As some optional embodiments of this application, the weight composition ratio of the conjugated organic framework structure material, electron donor and electron acceptor in the photoactive layer is (0-0.3]:1:[1-2];
[0008] The conjugated organic framework material has the following structure:
[0009]
[0010] Where n is a natural number from 1 to 5, C is a carbon atom; H is a hydrogen atom; O is an oxygen atom; and N is a nitrogen atom.
[0011] On the other hand, this application also provides a method for preparing an organic photovoltaic cell as described above, comprising the following steps:
[0012] After cleaning the glass substrate coated with ITO, it is dried with nitrogen and then exposed in an ozone chamber to obtain the ITO substrate.
[0013] The ZnO precursor solution was spin-coated onto the ITO substrate in dry air as an electron transport layer; after coating, annealing was performed to obtain the ZnO layer-ITO substrate; the ZnO layer-ITO substrate was then transferred to an argon-filled glove box for later use.
[0014] A photoactive solution is obtained by mixing conjugated organic framework materials, electron donors and electron acceptors in a certain proportion;
[0015] The photoactive solution is spin-coated onto the ZnO-ITO substrate to obtain a photoactive ZnO-ITO substrate; the photoactive ZnO-ITO substrate is then moved into an evaporator, and a molybdenum trioxide intermediate layer and an Ag layer are deposited onto the hole transport layer surface using a shadow mask to obtain an organic photovoltaic cell.
[0016] As some optional embodiments of this application, the cleaning agent used to clean the glass substrate coated with ITO includes at least one of detergent, acetone, and deionized water.
[0017] As some optional embodiments of this application, the exposure treatment takes 25-35 minutes.
[0018] As some optional embodiments of this application, the rotation speed of the ZnO precursor liquid being spin-coated onto the ITO substrate in dry air is 5800-6200 rpm, and the rotation time is 25-35 s.
[0019] As some optional embodiments of this application, the annealing temperature of the annealing treatment is 120-140℃, the annealing time is 25-35min, and the thickness of the ZnO layer is 25nm-35nm.
[0020] As some optional embodiments of this application, the solubility of the photoactive solution is 8–20 mg / mL. -1 .
[0021] As some optional embodiments of this application, the spin coating rate of the photoactive solution on the ZnO layer-ITO substrate is 1500 rpm, and the thickness of the photoactive layer is 10 nm-200 nm.
[0022] On the other hand, embodiments of this application also provide: an application of a conjugated organic framework structure material, wherein the conjugated organic framework structure material is used to prepare organic photovoltaic cells;
[0023] The conjugated organic framework material has the following structure:
[0024]
[0025] Where n is a natural number from 1 to 5, C is a carbon atom; H is a hydrogen atom; O is an oxygen atom; and N is a nitrogen atom.
[0026] When the conjugated organic framework structure material is used to prepare organic photovoltaic cells, it is prepared by the method described above.
[0027] The beneficial effects of the technical solution described in this application are:
[0028] This application incorporates conjugated organic framework materials during polymer synthesis. By forming complementary light absorption with the original active layer or providing additional electron separation and transport channels, it enhances exciton separation and transport, thereby improving the photoelectric conversion efficiency of organic photovoltaic (PV) devices to some extent. Specifically, this application applies the conjugated organic framework material to the active layer of an organic PV cell. Due to the ordered framework structure and stacking properties of the conjugated organic framework material, it can form a porous three-dimensional structure. Furthermore, its surface adsorption can fix small molecules on its surface, maintaining a certain morphological structure. In addition, its well-ordered stacking provides high charge transport, promoting exciton transport and providing new channels for exciton separation, thus improving the short-circuit current and photoelectric conversion efficiency of the organic PV cell, demonstrating potential application value in the photovoltaic field. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.
[0030] Figure 1 Optical images of the conjugated organic framework structure crystal materials of Examples 1-6 of this invention;
[0031] Figure 2 The X-ray diffraction pattern of the conjugated organic framework structure crystal material of Embodiment 1 of the present invention is shown below.
[0032] Figure 3 The image shows the Raman spectrum of the conjugated organic framework structure crystal material of Example 1 of this invention.
[0033] Figure 4 These are thickness measurement diagrams of the conjugated organic framework structure crystal materials in Examples 1-6 of the present invention.
[0034] Figure 5 This is a schematic diagram of the experimental setup for the conjugated organic framework structure crystal material of Embodiment 1 of the present invention; Figure 6 The washed M1 material, fresh M1 material, and PC obtained in Embodiment 3 of the present invention are examples of materials that can be used to describe the process of obtaining ... 71 BM's XRD test results.
[0035] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0037] Organic photovoltaic cells (OSCs) are photovoltaic devices based on organic materials that convert light energy into electrical energy. Among them, bulk heterojunction (BHJ) cells are a common structure that improves photoelectric conversion efficiency by forming a heterojunction within organic semiconductor materials. Thanks to continuous research efforts, the photoelectric conversion efficiency of BHJ cells has been constantly improved, exceeding 20%.
[0038] Although BHJ cells have made significant progress in photoelectric conversion efficiency, they still lag behind silicon-based and perovskite photovoltaic cells. Meanwhile, the stability of organic photovoltaic cells is receiving increasing attention.
[0039] Numerous studies have shown a strong correlation between the degradation of the active layer and device degradation in BHJ solar cells. This is due to the structure of the bulk heterojunction. The active layer typically comprises multiple phases, such as a donor phase, an acceptor phase, and a donor-acceptor mixture. The dissociation of photogenerated carriers requires a sufficient donor / acceptor (D / A) interface in the homogeneous amorphous phase, and the transport of the generated free carriers (whose maximum diffusion distance is only 20 nm) in the crystalline phase to form a photocurrent. Any physical process that leads to a reduction in the D / A interface and excessive phase separation size can adversely affect the photocurrent, resulting in a sharp decline in exciton separation and charge transport efficiency.
[0040] Because organic materials have relatively low glass transition temperatures, their blended structures are often in a metastable state. Over time, this metastable structure may gradually decay and tend to transition from the initial thermodynamic metastable state to a thermodynamic equilibrium state. This decay phenomenon further affects the photoelectric conversion efficiency and the stability of the active layer of organic photovoltaic cells.
[0041] Therefore, in order to further promote the commercialization of organic photovoltaic cells and expand their potential application areas, it is necessary to solve the problems of active layer stability and photoelectric conversion efficiency.
[0042] During the applicant's research, it was discovered that the aforementioned technical problems can be addressed by optimizing the synthesis and preparation processes of organic materials, improving battery structures, and exploring new organic photovoltaic materials. Simultaneously, it is necessary to strengthen research and deepen understanding of the stability issues of organic photovoltaic cells in order to better control and prevent device degradation. Furthermore, to improve the photoelectric conversion efficiency of organic photovoltaic cells, further research can be conducted by optimizing the selection and ratio of donor and acceptor materials, improving the phase separation morphology in the active layer, and regulating carrier transport pathways. In addition, the photoelectric conversion efficiency and stability can be improved by designing and developing novel organic photovoltaic device structures, such as organic photovoltaic cells with multi-junction structures.
[0043] Based on this, embodiments of this application provide an organic photovoltaic cell, including: an ITO substrate, a photoactive layer, and a metal electrode;
[0044] The photoactive layer is composed of a conjugated organic framework material, an electron donor, and an electron acceptor; the weight ratio of the conjugated organic framework material, the electron donor, and the electron acceptor in the photoactive layer is (0-0.3):1:[1-2].
[0045] The conjugated organic framework material has the following structure:
[0046]
[0047] Where n is a natural number from 1 to 5, C is a carbon atom; H is a hydrogen atom; O is an oxygen atom; and N is a nitrogen atom.
[0048] It should be noted that the organic photovoltaic cell also includes structures such as a transparent electrode, a first buffer layer, and a second buffer layer. The transparent electrode can be a conductive polymer, metal nanowires, doped metal oxides, or zinc oxide, etc. The buffer layer typically refers to a material located between the solar cell and the glass in a solar cell module. Its main function is to absorb light in the red edge region of the solar spectrum, preventing the loss of photoelectric conversion efficiency caused by transmission and reflection. Furthermore, the buffer layer can reduce the number of hot carriers on the surface of the photovoltaic cell, improve current matching, and thus increase the conversion efficiency of the photovoltaic cell.
[0049] It should be noted that the conjugated organic frameworks are a class of crystalline organic porous materials composed of organic structural units linked by covalent bonds. They possess high crystallinity and tunable pore structures, and are widely used in fields such as chemistry, materials science, molecular science, and biology. The pore size, specific surface area, and function of conjugated organic frameworks can all be controlled by selecting different synthetic methods, thus giving them high designability.
[0050] In some embodiments, the organic photovoltaic cell described in this application has a short-circuit current density of 13.65 mA / cm-15.55 mA / cm, an open-circuit voltage of 0.788 V-0.798 V, a fill factor of 0.60-0.68, and a photothermal conversion efficiency of 6.56%-7.57%.
[0051] In some embodiments, the method for preparing the above-mentioned organic photovoltaic cell includes the following steps:
[0052] After cleaning the glass substrate coated with ITO, it is dried with nitrogen and then exposed in an ozone chamber to obtain the ITO substrate.
[0053] The ZnO precursor solution was spin-coated onto the ITO substrate in dry air as an electron transport layer; after coating, annealing was performed to obtain the ZnO layer-ITO substrate; the ZnO layer-ITO substrate was then transferred to an argon-filled glove box for later use.
[0054] A photoactive solution is obtained by mixing conjugated organic framework materials, electron donors and electron acceptors in a certain proportion;
[0055] The photoactive solution is spin-coated onto the ZnO-ITO substrate to obtain a photoactive ZnO-ITO substrate; the photoactive ZnO-ITO substrate is then moved into an evaporator, and a molybdenum trioxide intermediate layer and an Ag layer are deposited onto the hole transport layer surface using a shadow mask to obtain an organic photovoltaic cell.
[0056] Specifically, the cleaning agent used to clean the ITO-coated glass substrate includes at least one of detergent, acetone, and deionized water.
[0057] Specifically, the exposure treatment takes 25-35 minutes; preferably, the treatment takes 30 minutes.
[0058] Specifically, the rotation speed for spin-coating the ZnO precursor solution onto the ITO substrate in dry air is 5800-6200 rpm, and the rotation time is 25-35 s. Preferably, the rotation speed is 6000 rpm, and the rotation time is 30 s.
[0059] Specifically, the annealing temperature for the annealing treatment is 120-140℃, and the annealing time is 25-35 min; the thickness of the ZnO layer is 25nm-35nm. Preferably, the annealing temperature for the annealing treatment is 130℃, and the annealing time is 30 min; the thickness of the ZnO layer is 30nm.
[0060] Specifically, the solubility of the photoactive solution is 8–20 mg / mL. -1 .
[0061] Specifically, the spin coating rate for spin coating the photoactive solution onto the ZnO layer-ITO substrate is 1500 rpm, and the thickness of the photoactive layer is 10 nm-200 nm.
[0062] This application also provides an application of a conjugated organic framework structure material, which is used to prepare organic photovoltaic cells;
[0063] The conjugated organic framework material has the following structure:
[0064]
[0065] Where n is a natural number from 1 to 5, C is a carbon atom; H is a hydrogen atom; O is an oxygen atom; and N is a nitrogen atom.
[0066] When the conjugated organic framework structure material is used to prepare organic photovoltaic cells, it is prepared by the method described above.
[0067] As can be seen, this application utilizes highly ordered conjugated organic framework (COF) materials as additional exciton transport and separation channels in the active layer of organic photovoltaic cells, thereby improving the short-circuit current and photoelectric conversion efficiency of organic photovoltaic cells. COF surface adsorption can immobilize small molecules on its surface, thus maintaining the morphology and structure of the acceptor phase, and has potential application value in the photovoltaic field.
[0068] The technical solutions described in this application will be further described in detail below with reference to specific embodiments, so as to enable those skilled in the art to understand the technical solutions described in this application:
[0069] Example 1
[0070] When the COF structure material M1 with n=1 is blended into the active layer, the COF material structure is as follows:
[0071]
[0072] The device fabrication process is as follows: First, the ITO-coated glass substrate was cleaned with detergent, acetone, and deionized water and dried with nitrogen, followed by exposure in an ozone chamber for 30 minutes. Next, a ZnO precursor solution was spin-coated onto the ITO substrate in dry air at a rotation rate of 6000 rpm for 30 seconds to prepare an electron transport layer. This was then annealed on a hot plate at 130°C for 30 minutes to form a thin ZnO layer (approximately 30 nm). Finally, the coated substrate was transferred to an argon-filled glove box. The photoactive layer used was the polymer PTB7-Th, and the acceptor was PC. 71 BM, using 1,8-diiodozinc alkyl ether (DIO) as an additive at a concentration of 3%, with an optimized total concentration of 10 mg / mL. -1 Standard devices were fabricated. For comparison, M1 was added at weight ratios of 1%, 3%, 5%, 7%, and 9% and then spin-coated at 1500 rpm, resulting in thicknesses of approximately 100 nm. The resulting device was then transferred to an evaporator, where, under high vacuum, a molybdenum trioxide intermediate layer (MoO3, 10 nm) and an Ag layer (100 nm) were deposited onto the hole transport layer MoO3 surface using a shadow mask. Each device had an area of 0.1 square centimeters.
[0073] Among them, the active layer PTB7-Th:PC based on 3% DIO is used. 71 Performance of photovoltaic cells with different contents of material M1 (AM1.5G, 100mW / cm) 2 The device parameters obtained under standard sunlight are shown in Table 1:
[0074] Table 1:
[0075]
[0076] The experimental results show that the short-circuit current of the device gradually increases when COF is added to the standard device, reaching 15.55 mA / cm² when the equivalent is 7%. 2 The highest short-circuit current, combined with data showing that devices with 7% COF material added to the active layer have the highest photoelectric conversion efficiency.
[0077] Jsc refers to Junction Short-Circuit Current Density, one of the most commonly used performance parameters of photovoltaic (PV) cells. It refers to the value of the short-circuit current density output by the PV cell under illumination. Jsc is related to the charge separation efficiency and photoelectric conversion efficiency of the PV cell. Voc refers to Open-Circuit Voltage, which is the cell voltage measured when the cell is not connected to a load. FF refers to Fill Factor, a measure of the quality of a solar cell (series resistance and parallel resistance). The fill factor FF is defined as the actual maximum output power divided by the ideal target output power. PCE refers to Photovoltaic Energy Conversion Efficiency, which refers to the efficiency of converting light energy into heat energy, and can also be understood as the photoelectric conversion efficiency of the solar cell. It is one of the important indicators for measuring the performance of solar cells and is of great significance for improving the efficiency of solar energy utilization.
[0078] Example 2:
[0079] To verify the regulatory effect of COF materials, a device was fabricated by blending material M1 from Example 1 into the active layer without the addition of DIO. The device fabrication process was the same as in Example 1. As a control, M1 was added at a weight ratio of 7% and then spin-coated at a speed of 1500 rpm, resulting in a thickness of approximately 100 nm. After being placed in air for 10 seconds, it was transferred to an evaporator. Under high vacuum, a molybdenum trioxide intermediate layer (MoO3, 10 nm) and an Ag layer (100 nm) were deposited on the surface of the hole transport layer MoO3 using a shadow mask. The device was continuously scanned nine times under standard illumination. The experimental results showed that, in the standard device with 7% COF added but DIO removed, the current gradually increased significantly with multiple scans.
[0080] Example 3:
[0081] To understand the effect of COF materials on the active layer, PTB7-Th:PC was used. 71 A 10 mg / mL chlorobenzene solution was prepared by mixing BM at a ratio of 1:1.5. M1 material was added, and the solution was sonicated for 30 min and allowed to stand overnight. M1 was filtered out using a filter and divided into two parts. One part was directly measured, while the other part was washed 10 times with chlorobenzene and then analyzed separately using transmission electron microscopy (TEM). Figure 3 and Figure 4 The unwashed M1 material surface adsorbed a large amount of material, which was later identified as PC by spectral analysis. 71 BM, and the washed M1 material also had a small amount of material attached, indicating that the COF material can adsorb PC.71 BM allows the acceptor phase to stack better and has a certain fixation effect, which will be beneficial to phase separation and phase stability, thereby improving short-circuit current and device photoelectric conversion efficiency.
[0082] Example 4:
[0083] The washed M1 material obtained in Example 3 and the unblended M1 material were prepared into a 10 mg / mL solution in chlorobenzene. These solutions were then mixed with 30 mg / mL polystyrene (PS) at a volume ratio of 1:1 and coated onto thin films. The absorption spectrum of the washed M1 material was obtained by coating the films with pure PS solution to remove spectral background for comparison. 71 Compare the BM spectra, such as Figure 5 Based on the spectrum, PC 71 BM adsorption and incorporation into the COF material provide new channels for exciton separation and promote their transport. Washed M1 material obtained in Example 3, fresh M1 material, and PC were used. 71 BM performed XRD tests as follows: Figure 6 Both washed and fresh M1 samples showed distinct diffraction peaks without significant changes, indicating that PC 71 BM does not disrupt the structure of COF material; instead, it acts as a rod in the active layer to perform additional charge transport and separation, thereby improving the short-circuit current of organic photovoltaic cells and the efficiency of the devices.
[0084] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
Claims
1. An organic photovoltaic cell, characterized in that, include: ITO substrate, photoactive layer, and metal electrode; The photoactive layer is composed of a conjugated organic framework material, an electron donor, and an electron acceptor.
2. The organic photovoltaic cell according to claim 1, characterized in that, The weight ratio of the conjugated organic framework material, electron donor, and electron acceptor in the photoactive layer is (0-0.3):1:[1-2]. The conjugated organic framework material has the following structure: Where n is a natural number from 1 to 5, C is a carbon atom; H is a hydrogen atom; O is an oxygen atom; and N is a nitrogen atom.
3. A method for preparing an organic photovoltaic cell as described in any one of claims 1-2, characterized in that, Includes the following steps: After cleaning the glass substrate coated with ITO, it is dried with nitrogen and then exposed in an ozone chamber to obtain the ITO substrate. The ZnO precursor solution was spin-coated onto the ITO substrate in dry air to serve as an electron transport layer. After coating, annealing is performed to obtain a ZnO layer-ITO substrate; The ZnO layer-ITO substrate was transferred to an argon-filled glove box for later use. A photoactive solution is obtained by mixing conjugated organic framework materials, electron donors and electron acceptors in a certain proportion; The photoactive solution is spin-coated onto the ZnO layer-ITO substrate to obtain the photoactive layer-ZnO layer-ITO substrate. The photoactive layer-ZnO layer-ITO substrate is moved into an evaporator, and a molybdenum trioxide intermediate layer and an Ag layer are deposited on the surface of the hole transport layer using a shadow mask to obtain an organic photovoltaic cell.
4. The method for preparing organic photovoltaic cells according to claim 3, characterized in that, The cleaning agent used to clean the ITO-coated glass substrate includes at least one of detergent, acetone, and deionized water.
5. The method for preparing organic photovoltaic cells according to claim 3, characterized in that, The exposure treatment takes 25-35 minutes.
6. The method for preparing organic photovoltaic cells according to claim 3, characterized in that, The rotation speed for spin-coating the ZnO precursor liquid onto the ITO substrate in dry air is 5800-6200 rpm, and the rotation time is 25-35 s.
7. The method for preparing organic photovoltaic cells according to claim 3, characterized in that, The annealing temperature for the annealing treatment is 120-140℃, and the annealing time is 25-35 min; the thickness of the ZnO layer is 25nm-35nm.
8. The method for preparing organic photovoltaic cells according to claim 3, characterized in that, The concentration of the photoactive solution is 8–20 mg / mL. -1 .
9. The method for preparing organic photovoltaic cells according to claim 3, characterized in that, The spin coating rate for spin coating the photoactive solution onto the ZnO-ITO substrate is 1500 rpm, and the thickness of the photoactive layer is 10 nm-200 nm.
10. An application of a conjugated organic framework structure material, characterized in that, The conjugated organic framework structure material is used in the preparation of organic photovoltaic cells; The conjugated organic framework material has the following structure: Where n is a natural number from 1 to 5, C is a carbon atom; H is a hydrogen atom; O is an oxygen atom; and N is a nitrogen atom. When the conjugated organic framework structure material is used to prepare organic photovoltaic cells, it is prepared by the method described in any one of claims 3-9.