A method for preparing an organic solar cell suitable for non-halogen solvents

Abstract

The invention relates to a method for preparing an organic solar cell suitable for a non-halogen solvent, and belongs to the technical field of solar cells. The invention optimizes the solvent volatilization process and the phase separation of a photoactive material by ultra-low temperature freezing treatment of an active layer, and can effectively suppress the lateral irregular flow of an active layer solution in a large-area thin film, promote the uniform volatilization of the non-halogen solvent, and avoid the generation of a "coffee ring effect"; the invention significantly accelerates the volatilization speed of a high-boiling-point non-halogen solvent, and shortens the aggregation and precipitation time of the photoactive material; the invention effectively overcomes the common problems of serious aggregation of photoactive molecules and excessive phase separation in a non-halogen solvent system; the fast-evaporating solvent vapor of the invention can carry a large number of receptor molecules to move to the upper layer of the thin film, and form a more ideal vertical phase separation structure.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a method for preparing an organic solar cell suitable for a non-halogen solvent, and in particular to a large-area green preparation method for an organic solar cell and a module suitable for a non-halogen solvent. Background Art

[0002] Organic solar cells have become a hot topic in solar cell research in recent years due to their low cost, light weight and flexibility. Compared with silicon-based solar cells and perovskite solar cells, organic solar cells have shown great application advantages in portable devices, wearable devices, visual windows and building-integrated photovoltaics.

[0003] The green preparation of organic solar cell devices and modules using non-halogen solvents with low or no biotoxicity is a prerequisite for the commercial development and application of organic photovoltaics. However, in the process of large-scale preparation of organic solar cells using high-boiling point non-halogen solvents, problems such as uneven solvent evaporation of photoactive materials, uneven film surface, severe aggregation, and excessive phase separation are often encountered. These problems make solar cells prepared with non-halogen solvents show significantly worse photovoltaic performance than those prepared with halogenated solvents. Moreover, the slow evaporation rate of high-boiling point solvents exacerbates the lateral flow of solutions in large-area active layer films, thereby inducing a serious "coffee ring effect" and impairing the repeatability of large-area battery performance.

[0004] In the prior art, although some preparation methods have attempted to optimize the solvent evaporation process and the uniformity of the film, most methods still have the problems of long preparation cycle, low efficiency or can only process small-sized substrates. How to overcome the "coffee ring effect" that may be produced during the solvent evaporation process and the non-uniformity of large-area films in large-scale production is still the main challenge to achieve industrial production of organic solar cells. Summary of the invention

[0005] In view of the above problems, the present invention provides a method for preparing organic solar cells suitable for non-halogen solvents, which optimizes the solvent volatilization process and the phase separation of photoactive materials by ultra-low temperature freezing treatment of the active layer, significantly improves the photovoltaic performance of the cell, and improves the uniformity of large-area active layer films, providing an effective technical path for the large-scale production of high-efficiency organic solar cells.

[0006] The present invention provides a method for preparing an organic solar cell suitable for a non-halogen solvent, comprising:

[0007] Step S1, selecting a transparent conductive substrate as a battery anode and deep cleaning it; depositing a hole transport material on the cleaned substrate to modify the battery anode interface to obtain a substrate with a hole transport layer;

[0008] Exemplarily, the transparent conductive substrate is indium tin oxide ITO;

[0009] Preferably, the deep cleaning method in step S1 includes ultrasonic cleaning and plasma treatment, the purpose of which is to ensure that there are no pollutants on the surface of the ITO substrate;

[0010] Preferably, the hole transport material in step S1 includes an organic material or an inorganic material; the organic material includes PEDOT:PSS or 2-PACz; the inorganic material includes sodium molybdate;

[0011] Preferably, the specific steps of depositing the hole transport layer in step S1 include:

[0012] The hole transport material is coated onto the surface of the transparent conductive substrate by spin coating or blade coating, and annealing is performed to ensure uniform and good adhesion of the hole transport layer.

[0013] Furthermore, the temperature of the annealing treatment in step S1 is 100-150°C;

[0014] Step S2, dissolving the photoactive material in a non-halogen solvent to obtain an active layer mixed solution;

[0015] Applying the active layer mixed solution onto the hole transport layer to form an active layer wet film, thereby obtaining a wet film substrate having an active layer;

[0016] Preferably, the photoactive material in step S2 includes an organic polymer, a copolymer or a small molecule material; the non-halogen solvent includes an aromatic hydrocarbon solvent, an alcohol solvent or an ether solvent;

[0017] Exemplarily, the photoactive material includes PM6:L8BO-X active layer material; the PM6:L8BO-X active layer material includes a polymer donor PM6 and a non-fullerene acceptor L8-BO;

[0018] The non-halogen solvent includes o-xylene solvent, toluene, benzyl alcohol or oligoethylene glycol;

[0019] Furthermore, the concentration of the active layer mixed solution is 10 to 20 mg / mL;

[0020] The coating method includes spin coating or blade coating;

[0021] Furthermore, the spin coating speed is 1000 to 3000 rpm;

[0022] The thickness of the active layer wet film coated in step S2 is 100 to 200 nm;

[0023] The present invention sets the thickness of the coated active layer mixed solution to be 100-200 nm, which is beneficial for the organic solar cell to obtain excellent photoelectric conversion efficiency.

[0024] Step S3, quickly transferring the wet film substrate with the active layer into an ultra-low temperature liquid for ultra-low temperature treatment to obtain a substrate with a frozen film of the active layer;

[0025] Preferably, the ultra-low temperature liquid in step S3 includes liquid nitrogen, liquid helium, liquid argon, liquid hydrogen, liquid oxygen or liquid ammonia;

[0026] Preferably, the ultra-low temperature treatment time in step S3 is 10 to 15 seconds;

[0027] Step S4, annealing the substrate with the active layer frozen film to obtain an annealed substrate;

[0028] Preferably, the annealing temperature in step S4 is 80-120° C. and the annealing time is 10-20 min.

[0029] In the present invention, the substrate with the active layer film is subjected to high temperature annealing treatment. The annealing process can promote the arrangement of the molecular chains of the photoactive material, improve the conductivity and light absorption characteristics of the film, and thus improve the photoelectric performance of the battery. This process can significantly accelerate the volatilization of the high-boiling point non-halogen solvent, prompting the photoactive material to quickly precipitate and deposit on the surface of the hole transport layer film, avoiding excessive aggregation of the material. Moreover, the rapidly volatile solvent can carry the receptor molecules to the film surface in an orderly manner, which helps to form an ideal vertical phase separation structure and further improve the photoelectric conversion efficiency of the battery.

[0030] Step S5, spin coating and depositing an electron transport material on the annealed substrate to obtain an electron transport layer, and evaporating a metal electrode on the electron transport layer to obtain an organic solar cell;

[0031] Preferably, the electron transport material in step S5 includes an organic material or an inorganic material; the organic material includes PNDIT-F3N or PEN-Br; the inorganic material includes zinc oxide or tin oxide;

[0032] Preferably, the thickness of the electron transport layer in step S5 is 5 to 10 nm;

[0033] The spin coating speed in step S5 is 4000-4200 rpm;

[0034] The metal electrode comprises aluminum or silver;

[0035] The thickness of the metal electrode is 100-150 nm.

[0036] In the present invention, ultra-low temperature liquids such as liquid nitrogen, liquid helium, liquid argon, liquid hydrogen, liquid oxygen, and liquid ammonia are used to freeze the active layer wet film, which can quickly lock the phase structure of the donor component (active layer material) and avoid excessive aggregation and phase separation of the active layer material.

[0037] Another object of the present invention is to provide an organic solar cell suitable for non-halogen solvents, the organic solar cell comprising an active layer frozen film;

[0038] The active layer freezing film includes a photoactive material dissolved in a non-halogen solvent;

[0039] The photoactive material includes organic polymers, copolymers or small molecule materials; the non-halogen solvent includes aromatic hydrocarbon solvents, alcohol solvents or ether solvents.

[0040] The third object of the present invention is to provide an application of an organic solar cell suitable for a non-halogen solvent, further comprising step S6, packaging the organic solar cell obtained in step S5, and applying the packaged organic solar cell in a photovoltaic module.

[0041] The present invention effectively regulates the volatilization of the solution in the active layer film and the uniformity of the film during the preparation of small-area and / or large-area organic solar cells, thereby improving the photovoltaic performance of the organic cell, including the photoelectric conversion efficiency and efficiency reproducibility.

[0042] The technical solution of the present invention accelerates the volatilization of high-boiling-point non-halogen solvents and the precipitation and crystallization process of active layer materials by subjecting the active layer wet film to ultra-low temperature freezing treatment and high-temperature annealing treatment, significantly shortens the wetting time of active layer materials, solves the serious aggregation and excessive phase separation problems of photoactive materials in organic solar cells caused by non-halogen solvents, and further solves the serious efficiency loss problem caused by them. In addition, the ultra-low temperature freezing treatment technology of the active layer wet film of the present invention allows the high-boiling-point non-halogen solvent in the active layer film to thaw and volatilize simultaneously during the thermal annealing process, effectively reducing the real-time solvent content in the active layer film, and solving the problems of efficiency loss and poor reproducibility caused by the "coffee ring effect" caused by the lateral irregular flow of the active layer solution in large-area devices.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] (1) The technical solution of the present invention significantly accelerates the volatilization rate of the high-boiling-point non-halogen solvent and shortens the aggregation and precipitation time of the photoactive material;

[0045] (2) The present invention effectively overcomes the serious aggregation of photoactive molecules and excessive phase separation problems commonly seen in non-halogen solvent systems;

[0046] (3) The rapidly evaporating solvent vapor of the present invention can carry a large number of receptor molecules to move to the upper layer of the film, forming a more ideal vertical phase separation structure;

[0047] (4) The present invention performs pre-freezing treatment on the active layer, which can effectively suppress the lateral irregular flow of the active layer solution in the large-area film, promote the uniform volatilization of the non-halogen solvent, and avoid the generation of the "coffee ring effect".

[0048] (5) The present invention improves the photovoltaic performance and reproducibility of the organic solar cell module, thereby increasing the application value of the organic solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0050] Figure 1 A schematic diagram of a process flow chart for preparing an organic solar cell device according to an embodiment of the present invention;

[0051] Figure 2 A schematic diagram of a flow chart for preparing an organic solar cell device in a comparative example of the present invention;

[0052] Figure 3 A schematic diagram showing a comparison of the photoelectric conversion efficiency of organic solar cells based on different non-halogen solvents and active materials according to the present invention;

[0053] Figure 4 Schematic diagram of absorption spectra of active layers at different depths and donor / acceptor component ratios in the embodiments of the present invention and comparative examples;

[0054] Figure 5 Schematic diagram of optical photographs of large-area active layer films prepared based on high-boiling-point non-halogen solvents in the embodiments of the present invention and the comparative examples;

[0055] Figure 6 A schematic diagram of a large-area organic solar cell module applicable to the method of the present invention;

[0056] Figure 7 It is a schematic diagram comparing the photoelectric conversion efficiency of the organic solar cell module in the embodiment of the present invention and the comparative example. DETAILED DESCRIPTION

[0057] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0058] A specific embodiment of the present invention, as Figure 1-7 , discloses a method for preparing an organic solar cell suitable for non-halogen solvents, such as Figure 3 The figure is a schematic diagram of the comparison of the photoelectric conversion efficiency of organic solar cells based on different non-halogen solvents and active materials of the present invention; it shows that the cell prepared by the method of the present invention has a higher photoelectric conversion efficiency, and it shows the excellent universality of the method for a variety of non-halogen solvents. The present invention is marked as F-BHJ, and the comparative example is marked as BHJ.

[0059] Figure 4 The absorption spectra of the active layer at different depths in the embodiments of the present invention and the comparative examples and the ratio of donor / acceptor components show that the active layer film prepared by the method of the present invention has a higher concentration of acceptor molecules on the surface and a higher concentration of donor molecules at the bottom, which is beneficial to the transmission and extraction of charges; the present invention is marked as F-BHJ and the comparative example is marked as BHJ.

[0060] Figure 5 Optical photographs of large-area active layer films prepared based on high-boiling-point non-halogen solvents in the examples of the present invention and the comparative examples show that the large-area active layer film prepared by the method of the present invention is more uniform and has no obvious "coffee ring".

[0061] Figure 7 The figure compares the photoelectric conversion efficiency of the organic solar cell modules in the embodiment of the present invention and the comparative example, showing that the organic module prepared by the method of the present invention has a higher photoelectric conversion efficiency; the present invention is marked as F-BHJ, and the comparative example is marked as BHJ.

[0062] In order to illustrate the effectiveness of the method proposed in the present invention, the above technical solution of the present invention is described in detail below through a specific embodiment, and the specific implementation steps are as follows:

[0063] Embodiment 1

[0064] A method for preparing an organic solar cell suitable for a non-halogen solvent, comprising:

[0065] Step S1, selecting an indium tin oxide (ITO) substrate as a battery anode and ultrasonically cleaning it; coating a hole transport material on the surface of a transparent conductive substrate by spin coating or scraping on the cleaned substrate, and performing an annealing treatment at 100 to 150° C. to modify the battery anode interface and ensure that the hole transport layer is uniform and well adhered;

[0066] Step S2, dissolving the PM6:L8BO-X active layer material in o-xylene solvent to obtain a 10-20 mg / mL active layer mixed solution;

[0067] The active layer mixed solution is spin-coated or scraped onto the hole transport layer at 1000 to 3000 rpm to form an active layer wet film with a thickness of 100 to 200 nm, thereby obtaining a wet film substrate with an active layer;

[0068] Step S3, quickly transferring the wet film substrate with the active layer into an ultra-low temperature liquid for ultra-low temperature treatment for 10 to 15 seconds to obtain a substrate with a frozen film of the active layer;

[0069] Step S4, annealing the substrate with the active layer frozen film at 80-120° C. for 10-20 min to obtain an annealed substrate;

[0070] Step S5, spin coating and depositing a 5-10 nm electron transport layer on the annealed substrate, and evaporating a 100-150 nm metal electrode aluminum or silver on the electron transport layer to obtain an organic solar cell;

[0071] Another object of the present invention is to provide an organic solar cell suitable for non-halogen solvents, the organic solar cell comprising an active layer frozen film;

[0072] The active layer freezing film includes a photoactive material dissolved in a non-halogen solvent;

[0073] The photoactive material includes organic polymers, copolymers or small molecule materials; the non-halogen solvent includes aromatic hydrocarbon solvents, alcohol solvents or ether solvents.

[0074] The third object of the present invention is to provide an application of an organic solar cell suitable for a non-halogen solvent, further comprising step S6, packaging the organic solar cell obtained in step S5, and applying the packaged organic solar cell in a photovoltaic module.

[0075] Embodiment 2

[0076] A method for preparing a large-area organic solar cell suitable for a non-halogen solvent comprises:

[0077] Based on the method of embodiment 1, a plurality of sub-cells with metal electrodes to be evaporated are obtained;

[0078] For large-area organic photovoltaic modules, a laser etcher is required to vertically groove the active layer material and transmission material film of each sub-cell of the metal electrode to be evaporated in advance, so that the sub-cells of the metal electrode to be evaporated are connected end to end to form a series circuit to obtain a large-area organic photovoltaic module.

[0079] Evaporating 100-150nm of metal electrode aluminum or silver on the electron transport layer of each sub-cell of the metal electrode to be evaporated to obtain a plurality of organic solar cells connected in series;

[0080] A plurality of organic solar cells connected in series are packaged, and the packaged organic solar cells are used in a photovoltaic module.

[0081] Another object of the present invention is to provide a large-area organic solar cell suitable for non-halogen solvents, the large-area organic solar cell comprising an active layer frozen film;

[0082] The active layer freezing film includes a photoactive material dissolved in a non-halogen solvent;

[0083] The photoactive material includes organic polymers, copolymers or small molecule materials; the non-halogen solvent includes aromatic hydrocarbon solvents, alcohol solvents or ether solvents.

[0084] The third object of the present invention is to provide an application of large-area organic solar cells suitable for non-halogen solvents.

[0085] Comparative Example 1

[0086] The influence of the active layer freezing treatment on the performance of the small-area organic solar cell photovoltaic device in the present invention is carried out by using the control variable method, and the specific steps are as follows:

[0087] Step S1, selecting an indium tin oxide (ITO) substrate as a battery anode and ultrasonically cleaning it; coating a hole transport material on the surface of a transparent conductive substrate by spin coating or scraping on the cleaned substrate, and performing an annealing treatment at 100 to 150° C. to modify the battery anode interface and ensure that the hole transport layer is uniform and well adhered;

[0088] Step S2, dissolving the PM6:L8BO-X active layer material in o-xylene solvent to obtain a 10-20 mg / mL active layer mixed solution;

[0089] The active layer mixed solution is spin-coated or scraped onto the hole transport layer at 1000 to 3000 rpm to form an active layer thin film with a thickness of 100 to 200 nm, thereby obtaining a thin film with an active layer;

[0090] Step S3, annealing the substrate with the active layer at 80-120° C. for 10-20 min to obtain an annealed substrate;

[0091] Step S4, spin coating and depositing a 5-10 nm electron transport layer on the annealed substrate, and evaporating a 100-150 nm metal electrode aluminum or silver on the electron transport layer to obtain an organic solar cell;

[0092] The organic solar cells prepared in Example 1 were based on different photoactive materials and non-halogen solvents, and all were characterized for photoelectric conversion efficiency. In addition, the active layer wet films of Example 1 and Comparative Example 1 were tested for depth-dependent absorption spectra, and the results were as follows:

[0093] Figure 3 The comparison of the photoelectric conversion efficiency of the organic solar cell in Example 1 of the present invention and the comparative example is shown, indicating that the organic solar cell prepared by the present invention has a higher photoelectric conversion efficiency, confirming the excellent universality of the present invention for different non-halogen solvents; F-BHJ is Example 1, and BHJ is Comparative Example 1.

[0094] Figure 4 The absorption spectra of the active layer wet films prepared in Example 1 of the present invention and the comparative example at different depths and the donor / acceptor ratio are shown, indicating that the active layer film prepared in the present invention has a higher concentration of acceptor molecules on the surface and a higher concentration of donor molecules at the bottom, which is beneficial to the transfer and extraction of charges. F-BHJ is Example 1, and BHJ is Comparative Example 1.

[0095] Figure 5 Optical photographs of the large-area active layer films prepared by the embodiments of the present invention and the comparative examples are shown, and it is found that the large-area active layer films prepared by the method of the present invention are more uniform, and no obvious "coffee ring" is present.

[0096] Figure 7 The photoelectric conversion efficiency and output power of the organic solar cell modules prepared in the embodiment of the present invention and the comparative example are compared. The cell prepared in the present invention has higher photoelectric conversion efficiency and output power.

[0097] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing an organic solar cell suitable for a non-halogen solvent, characterized in that: include: Step S1, selecting a conductive substrate, cleaning it, and depositing a hole transport material to obtain a substrate having a hole transport layer; Step S2, dissolving the photoactive material in a non-halogen solvent to obtain an active layer mixed solution; Applying the active layer mixed solution onto the hole transport layer to form an active layer wet film, thereby obtaining a wet film substrate having an active layer; Step S3, subjecting the wet film substrate with the active layer to ultra-low temperature treatment to obtain a substrate with a frozen thin film of the active layer; Step S4, annealing the substrate with the active layer frozen film; Step S5: spin-coating and depositing electron transport materials on the annealed substrate, and evaporating metal electrodes to obtain an organic solar cell.

2. The method for preparing an organic solar cell suitable for a non-halogen solvent according to claim 1, characterized in that: In step S1, the hole transport material includes an organic material or an inorganic material.

3. The method for preparing an organic solar cell suitable for a non-halogen solvent according to claim 1, characterized in that: In step S2, the photoactive material includes an organic polymer, a copolymer or a small molecule material; and the non-halogen solvent includes an aromatic hydrocarbon solvent, an alcohol solvent or an ether solvent.

4. The method for preparing an organic solar cell suitable for a non-halogen solvent according to claim 1, characterized in that: The ultra-low temperature liquid in step S3 includes liquid nitrogen, liquid helium, liquid argon, liquid hydrogen, liquid oxygen or liquid ammonia.

5. The method for preparing an organic solar cell suitable for a non-halogen solvent according to claim 1, characterized in that: The ultra-low temperature treatment time in step S3 is 10 to 15 seconds.

6. The method for preparing an organic solar cell suitable for a non-halogen solvent according to claim 1, characterized in that: The annealing temperature in step S4 is 80-120° C. and the time is 10-20 min.

7. The method for preparing an organic solar cell suitable for a non-halogen solvent according to claim 1, characterized in that: In step S5, the electron transport material includes organic material or inorganic material.

8. An organic solar cell suitable for non-halogen solvents prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The organic solar cell comprises an active layer frozen film; The active layer freezing film includes a photoactive material dissolved and a non-halogen solvent.

9. The organic solar cell suitable for non-halogen solvents according to claim 8, characterized in that: The photoactive material includes organic polymers, copolymers or small molecule materials; the non-halogen solvent includes aromatic hydrocarbon solvents, alcohol solvents or ether solvents.

10. An application of an organic solar cell suitable for non-halogen solvents according to claim 8, characterized in that: The organic solar cell obtained in step S5 is packaged, and the packaged organic solar cell is applied to a photovoltaic module.

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