Organic solar cell and preparation method thereof

Abstract

The invention discloses an organic solar cell and a preparation method thereof, and relates to the technical field of cells. The method comprises the following steps: spin-coating an anode interface modification layer solution on a conductive substrate to form an anode interface modification layer; spin-coating the photosensitive active layer solution on the anode interface modification layer to form a photosensitive active layer; the first solvent is preheated so that the first solvent can generate steam, and the boiling point of the first solvent is higher than 120 DEG C; placing the photosensitive active layer in a normal temperature state and the heated first solvent in the same closed environment to enable steam generated by the first solvent to dissolve a material in the photosensitive active layer so as to form a photosensitive active layer with a phase separation nanostructure; spin-coating the photosensitive active layer with the cathode interface modification layer solution to form a cathode interface modification layer; and forming a metal electrode on the surface of the cathode interface modification layer. The invention aims to solve the problem that the efficiency of the organic solar cell is reduced due to excessive phase separation of the photosensitive active layer.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to an organic solar cell and a preparation method thereof. Background Art

[0002] Organic solar cells are mainly based on carbon-based materials, with advantages such as light weight, semi-transparency and roll-to-roll production, and have great potential in solving energy problems. High-efficiency organic solar cells generally require the photosensitive active layer to have a suitable phase separation size and crystalline domain to achieve effective exciton dissociation and fast charge transport. In addition to designing new organic semiconductor materials, additional post-processing processes are required to optimize the morphology of the active layer.

[0003] In the related art, solvent annealing is generally used to optimize the morphology of the photosensitive active layer. However, if a high boiling point solvent (>120°C) is used for thermal annealing, the traditional preparation process requires the high boiling point solvent and the photosensitive active layer placed in the same closed environment to be heated simultaneously, which will cause the photosensitive active layer to undergo an additional thermal annealing process, often resulting in excessive phase separation, making it impossible to achieve efficient exciton dissociation, and increasing carrier recombination, limiting the improvement of the efficiency of organic solar cells. Summary of the invention

[0004] The present invention provides an organic solar cell and a preparation method thereof, aiming to solve the problem that excessive phase separation of a photosensitive active layer of the organic solar cell occurs due to thermal annealing treatment, thereby reducing the efficiency of the organic solar cell.

[0005] In a first aspect, the present invention provides a method for preparing an organic solar cell, the method comprising:

[0006] Providing a conductive substrate, and spin-coating an anode interface modification layer solution on the conductive substrate to form an anode interface modification layer on the surface of the conductive substrate;

[0007] Preparing a photosensitive active layer solution, and spin-coating the photosensitive active layer solution on the anode interface modification layer to form a photosensitive active layer on the surface of the anode interface modification layer;

[0008] Preheating the first solvent so that the first solvent can generate steam, wherein the boiling point of the first solvent is higher than 120° C.;

[0009] placing the photosensitive active layer at room temperature and the first solvent after heating in the same closed environment, so that the vapor generated by the first solvent dissolves the material in the photosensitive active layer to form a photosensitive active layer with a phase-separated nanostructure;

[0010] Spin coating a cathode interface modification layer solution on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer;

[0011] A metal electrode is formed on the surface of the cathode interface modification layer.

[0012] In a second aspect, the present invention provides an organic solar cell, wherein the organic solar cell is prepared by using the above-mentioned method for preparing an organic solar cell.

[0013] The present application provides an organic solar cell and a preparation method thereof. The method comprises the following steps: providing a conductive substrate, and spin-coating an anode interface modification layer solution on the conductive substrate to form an anode interface modification layer on the surface of the conductive substrate; preparing a photosensitive active layer solution, and spin-coating the photosensitive active layer solution on the anode interface modification layer to form a photosensitive active layer on the surface of the anode interface modification layer; preheating a first solvent so that the first solvent can generate steam, and the boiling point of the first solvent is higher than 120° C.; placing the photosensitive active layer at room temperature and the heated first solvent together in the same closed environment so that the steam generated by the first solvent can contact the photosensitive active layer at room temperature, and the molecules of the photosensitive active layer will be redissolved, thereby promoting further movement of the molecules to form a photosensitive active layer with a more controllable phase-separated nanostructure; spin-coating a cathode interface modification layer solution on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer; and forming a metal electrode on the surface of the cathode interface modification layer. It can not only avoid excessive phase separation of the photoactive layer caused by additional thermal annealing, but also greatly simplify the solvent annealing process of the photoactive layer of the organic solar cell, and is suitable for the scenario of solvent annealing of the photoactive layer with a high boiling point solvent, thereby improving the efficiency of the organic solar cell. From an industrial perspective, there is no need to heat the photoactive layer, which reduces the preparation cost of the organic solar cell and has a good prospect for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0015] Figure 1 The related technology provides an application scenario diagram of a thermal annealing post-treatment process;

[0016] Figure 2 The related technology provides an application scenario diagram of a solvent annealing post-treatment process;

[0017] Figure 3is a schematic flow chart of a method for preparing an organic solar cell provided by an embodiment of the present invention;

[0018] Figure 4 It is a schematic diagram of the molecular structure of PM6 and BTP-eC9-4F provided in an embodiment of the present invention;

[0019] Figure 5 This is an application scenario diagram of a preheating solvent annealing post-treatment process provided by an embodiment of the present invention;

[0020] Figure 6 is a current density-voltage curve diagram of an organic solar cell obtained by a solvent annealing post-treatment process at different preheating temperatures corresponding to Example 1 provided in an embodiment of the present invention;

[0021] Figure 7 is a current density-voltage curve of an organic solar cell obtained by a solvent annealing post-treatment process with different photosensitive active layer treatment times corresponding to Example 1 provided in an embodiment of the present invention;

[0022] Figure 8 is a current density-voltage curve diagram of an organic solar cell prepared in Comparative Example 1 and Comparative Example 2 provided in an embodiment of the present invention;

[0023] Fig. 9 It is a current density-voltage curve diagram of an organic solar cell prepared in Comparative Example 3 and Example 2 provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0026] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0027] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] In related technologies, such as Figure 1 As shown, a thermal annealing process can be used to optimize the morphology of the photosensitive active layer. Specifically, the spin-coated photosensitive active layer can be directly placed on a heating platform for heating annealing. However, if thermal annealing is used, excessive phase separation of the photosensitive active layer will occur, and efficient exciton dissociation cannot be achieved. It will also increase carrier recombination, limiting the improvement of the efficiency of organic solar cells.

[0030] like Figure 2 As shown, solvent annealing is also one of the effective post-treatment processes, which can rearrange the donor and acceptor molecules in the photosensitive active layer, thereby optimizing the morphology of the photosensitive active layer. The specific treatment steps are to place the spin-coated photosensitive active layer in a container filled with solvent, and then place the sealed container on a heating table. The solvent generates steam under the action of heating, which can selectively adjust the crystallinity of the donor material and the acceptor material in the photosensitive active layer, and significantly optimize the phase separation. For high-boiling point solvents, the container containing the solvent must be subjected to additional high-temperature assistance to generate steam. Since both the photosensitive active layer and the container containing the solvent are placed on the heating table, this inevitably leads to the need for additional thermal annealing of the photosensitive active layer, so it is difficult to be applied to large-scale industrial production. Secondly, high annealing temperature will cause excessive phase separation in the photosensitive active layer, resulting in the inability of excitons to achieve efficient dissociation, and will also increase carrier recombination, thereby limiting the improvement of the efficiency of organic solar cells. Therefore, it is urgent to develop a solvent annealing process for photosensitive active layers with high boiling point solvents.

[0031] The present application provides an organic solar cell and a preparation method thereof, which can not only avoid excessive phase separation of the photosensitive active layer caused by the additional high temperature treatment used in the solvent annealing process of a high boiling point solvent, but also greatly simplify the solvent annealing process of the photosensitive active layer of the organic solar cell, reduce the preparation cost of the organic solar cell, and improve the efficiency of the organic solar cell, and has a good application prospect. Please refer to Figure 3 , Figure 3 The embodiment of the present invention provides a schematic flow chart of the steps of a method for preparing an organic solar cell.

[0032] like Figure 3As shown, the method for preparing the organic solar cell includes: step S101 to step S106.

[0033] S101, providing a conductive substrate, and spin-coating an anode interface modification layer solution on the conductive substrate to form an anode interface modification layer on the surface of the conductive substrate.

[0034] The conductive substrate can be any substrate that can be used for support and conduct electricity, such as transparent conductive glass, indium tin oxide, etc. The anode interface modification layer solution can be a PEDOT:PSS solution, which is used to prepare the anode interface modification layer, and the prepared anode interface modification layer is stacked with the conductive substrate.

[0035] Specifically, the ITO conductive glass can be placed in a beaker containing alcohol and subjected to ultrasonic treatment for 15-20 minutes, and then blown dry with nitrogen to remove the residual solvent on the surface. Subsequently, the clean ITO glass is subjected to UV treatment for 15-30 minutes to improve the hydrophilicity of the ITO glass surface.

[0036] Specifically, after the anode interface modification layer solution is cooled to room temperature, a spin coater is used to spin-coat the anode interface modification layer solution on the conductive substrate to form the anode interface modification layer on the surface of the conductive substrate.

[0037] The anode interface modification layer solution may be a PEDOT:PSS solution. The PEDOT:PSS solution is composed of two substances, PEDOT and PSS, and is an aqueous solution of a high molecular polymer with high conductivity.

[0038] Exemplarily, the thickness of the anode interface modification layer may be 5-40 nm.

[0039] For example, the PEDOT:PSS solution is spin-coated on the surface-modified transparent indium tin oxide glass, and the spin-coating speed may be 5000 rpm, so that the thickness of the prepared anode interface modification layer is 5-40 nm.

[0040] In some embodiments, the anode interface modification layer is subjected to thermal annealing treatment at a temperature of 100-160° C. and a time of 10-30 min, which can help improve the bonding strength between the anode interface modification layer and the conductive substrate.

[0041] Specifically, the anode interface modification layer can be annealed for 10-30 minutes using a heating stage, and the temperature can be set to 100-160°C.

[0042] S102, preparing a photosensitive active layer solution, and spin-coating the photosensitive active layer solution on the anode interface modification layer to form a photosensitive active layer on the surface of the anode interface modification layer.

[0043] The photosensitive active layer solution is a mixed solution formed by a donor material and an acceptor material.

[0044] In some embodiments, a donor material and an acceptor material are provided, and the mass ratio of the donor material to the acceptor material is 1:(0.5-4); the donor material and the acceptor material are dissolved in a second solvent to prepare a photosensitive active layer solution, and the concentration of the photosensitive active layer solution is 8-16 mg / ml. Thus, a photosensitive active layer solution of corresponding concentration can be prepared.

[0045] like Figure 4 As shown, the donor material may be a polymer donor material (PBDB-TF, PM6). The acceptor material may include an organic photovoltaic OPV material BTP-eC9-4F. The second solvent may be an organic solvent such as chloroform.

[0046] Specifically, the donor material PM6 and the acceptor material BTP-eC9-4F can be dissolved together in a chloroform solvent at a mass ratio of 1:(0.5-4), so that the concentration of the prepared photosensitive active layer solution is 8-16 mg / ml.

[0047] Preferably, the mass ratio of the donor material PM6 to the acceptor material BTP-eC9-4F is 1:1.2, and the concentration of the prepared photosensitive active layer solution is 15.4 mg / ml.

[0048] For example, the corresponding masses of donor material PM6 and acceptor material BTP-eC9-4F can be weighed according to a mass ratio of 1:1.2, placed in the same sample bottle, added with chloroform solvent, stirred at 50°C for 1 hour, and a photosensitive active layer solution with a concentration of 15.4 mg / ml can be prepared.

[0049] Specifically, a photosensitive active layer solution is spin-coated on the anode interface modification layer using a coating machine, thereby forming a photosensitive active layer on the surface of the anode interface modification layer. The thickness of the photosensitive active layer may be 40-300 nm.

[0050] The prepared photosensitive active layer and the anode interface modification layer are stacked.

[0051] Exemplarily, after the photosensitive active layer solution is cooled to room temperature, the photosensitive active layer solution is spin-coated on the anode interface modification layer at a spin coating speed of 2800 rpm, thereby forming a photosensitive active layer with a thickness of 40-300 nm on the surface of the anode interface modification layer.

[0052] S103, preheating the first solvent so that the first solvent can generate steam, and the boiling point of the first solvent is higher than 120°C.

[0053] like Figure 5As shown, the first solvent is a high boiling point solvent that has good solubility for at least one component in the photosensitive active layer. In the embodiment of the present application, the components of the photosensitive active layer include a donor material PM6 and an acceptor material BTP-eC9-4F, so the first solvent has good solubility for at least the donor material PM6 or the acceptor material BTP-eC9-4F. Preferably, the first solvent has good solubility for at least both the donor material PM6 and the acceptor material BTP-eC9-4F. The boiling point of a high boiling point solvent is generally higher than 120°C.

[0054] In some embodiments, the first solvent includes o-xylene solvent or o-chlorobromobenzene.

[0055] Among them, o-xylene solvent is a colorless transparent liquid, insoluble in water, but has good solubility for both donor material PM6 and acceptor material BTP-eC9-4F, and its boiling point is 143℃-145℃, which is a high boiling point solvent. o-Chlorobromobenzene solvent is a colorless liquid, has good solubility for both donor material PM6 and acceptor material BTP-eC9-4F, so it is often used as a solvent, and its boiling point is 204℃, which is also a high boiling point solvent.

[0056] For high-boiling-point solvents such as o-xylene solvent, there is no good way in the relevant technology to apply them to the solvent annealing treatment of the photosensitive active layer. The method provided in the present application can effectively apply high-boiling-point solvents such as o-xylene solvent to the solvent annealing treatment of the photosensitive active layer, which can not only avoid excessive phase separation of the photosensitive active layer caused by thermal annealing treatment, but also greatly simplify the annealing process of the photosensitive active layer of the organic solar cell, reduce the preparation cost of the organic solar cell, and improve the efficiency of the organic solar cell, and has a good application prospect.

[0057] In some embodiments, the temperature of the preheating treatment is 50-90° C.; and / or the time of the preheating treatment is 1-10 min.

[0058] Specifically, the high boiling point solvent can be placed separately in a sample bottle in advance, and then heat-treated after the sample bottle is sealed. The temperature of the preheating treatment is set to 50-90° C., and the time of the preheating treatment is set to 1-10 min.

[0059] It should be noted that the temperature and time of the preheating treatment are generally set according to actual conditions. Generally, the higher the temperature of the preheating treatment, the shorter the preheating treatment time can be, and the lower the temperature of the preheating treatment, the longer the preheating treatment time can be, as long as the first solvent can generate steam.

[0060] S104, placing the photosensitive active layer at room temperature and the heated first solvent in the same closed environment, so that the vapor generated by the first solvent dissolves the material in the photosensitive active layer to form a photosensitive active layer with a phase-separated nanostructure.

[0061] like Figure 5 As shown, in some embodiments, the photosensitive active layer at room temperature and the heated first solvent are placed in the same closed environment and left to stand for 1-5 minutes. After the photosensitive active layer at room temperature comes into contact with the vapor generated by the first solvent, the material in the photosensitive active layer will be redissolved, promoting further movement of the donor molecules and the acceptor molecules in the photosensitive active layer, thereby forming a photosensitive active layer with a phase-separated nanostructure.

[0062] The standing time is the processing time of the photosensitive active layer.

[0063] Since the pre-heating solvent annealing process provided in the embodiment of the present application promotes the phase separation of donor molecules and acceptor molecules in the photosensitive active layer by contacting steam with the photosensitive active layer, compared with the thermal annealing process, it can effectively avoid excessive phase separation of the photosensitive active layer, and is also beneficial for controlling the photosensitive active layer to form a suitable phase separation size and crystallization domain, thereby achieving effective exciton dissociation and rapid charge transfer, so as to form a photosensitive active layer with a better phase separation nanostructure.

[0064] Illustratively, the photosensitive active layer at room temperature can be placed in the middle of a clean culture dish, and then the heated first solvent can be directly placed in the culture dish containing the photosensitive active layer, and a lid can be added to form a closed environment. The photosensitive active layer is treated in this environment for 1-5 minutes. The heated first solvent will evaporate to form steam. When the photosensitive active layer comes into contact with the steam, the mobility of the molecular chain segments is enhanced, thereby accelerating the phase separation of the donor molecules and the acceptor molecules in the photosensitive active layer, so that the phase separation nanostructure of the donor molecules and the acceptor molecules in the photosensitive active layer tends to be ordered, that is, a photosensitive active layer with a phase separation nanostructure is formed.

[0065] It should be noted that the time for the photosensitive active layer to react with the vapor generated by the first solvent can be controlled according to the phase separation size and crystal domain required by the photosensitive active layer.

[0066] Through the solvent annealing method provided above, the photosensitive active layer can have a suitable phase separation size and crystal domain, which is conducive to achieving effective exciton dissociation and rapid charge transfer. It can also avoid excessive phase separation of the photosensitive active layer caused by thermal annealing treatment, greatly simplifying the annealing process of the photosensitive active layer of organic solar cells, and is suitable for scenarios where the photosensitive active layer is annealed with a high boiling point solvent, reducing the preparation cost of organic solar cells, and improving the efficiency of organic solar cells, and has a good application prospect.

[0067] S105, spin-coating the cathode interface modification layer solution on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer.

[0068] The cathode interface modification layer solution may be a PD I NN solution, which is used to prepare the cathode interface modification layer, and the prepared cathode interface modification layer is stacked with the photosensitive active layer.

[0069] In some embodiments, the PDI NN material can be dissolved in a methanol solvent to prepare a cathode interface modification layer solution with a concentration of 0.5-3 mg / ml.

[0070] Among them, PDI NN material is a common electron transport layer material, mainly used in organic solar cells. In the embodiment of the present application, PDI NN material can be used to prepare a cathode interface modification layer solution. PDI NN has excellent electron transport performance and good film-forming properties, and can effectively extract electrons from non-fullerene acceptors and polymer donors, thereby improving the efficiency of organic solar cells.

[0071] Preferably, the concentration of the cathode interface modification layer solution is 1 mg / ml.

[0072] Specifically, a coating machine can be used to spin-coat a cathode interface modification layer solution of corresponding concentration on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer. The thickness of the cathode interface modification layer can be 5-30 nm.

[0073] S106, forming a metal electrode on the surface of the cathode interface modification layer.

[0074] The metal electrode may include a silver electrode, a gold electrode or an aluminum electrode.

[0075] In some embodiments, a thermal evaporation device is used to dissolve the metal; based on a preset vacuum condition, the dissolved metal is evaporated onto the cathode interface modification layer to form a metal electrode on the surface of the cathode interface modification layer, and the thickness of the metal electrode is 40-200 nm. Thus, a metal electrode of a specific thickness can be prepared on the surface of the cathode interface modification layer.

[0076] Specifically, the common anode can be scraped out with tweezers and finally transferred to the evaporation chamber, where the cathode electrode is deposited by thermal evaporation under a high-pressure vacuum environment, thereby forming a metal electrode on the surface of the cathode interface modification layer, and the thickness of the metal electrode can be controlled within the range of 40-200nm.

[0077] For example, the silver metal is dissolved by thermal evaporation equipment under a vacuum degree of 5×10 -4Under the condition of Pa, metallic silver will liquefy, and at this time the liquid silver will vaporize onto the cathode interface modification layer to form a silver electrode with a thickness of 100nm, thereby preparing an organic solar cell.

[0078] The present application provides a method for preparing an organic solar cell, which comprises providing a conductive substrate, and spin-coating an anode interface modification layer solution on the conductive substrate to form an anode interface modification layer on the surface of the conductive substrate; preparing a photosensitive active layer solution, and spin-coating the photosensitive active layer solution on the anode interface modification layer to form a photosensitive active layer on the surface of the anode interface modification layer; preheating a first solvent so that the first solvent can generate steam, and the boiling point of the first solvent is higher than 120°C; placing the photosensitive active layer at room temperature and the heated first solvent in a closed environment, and the steam generated by the first solvent will re-dissolve the material in the photosensitive active layer at room temperature, promote further movement of molecules in the film, and form a photosensitive active layer with a better phase separation nanostructure. Spin-coating a cathode interface modification layer solution on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer; and forming a metal electrode on the surface of the cathode interface modification layer.

[0079] The method for preparing the organic solar cell provided by the present invention is described below in conjunction with specific embodiments.

[0080] Example 1

[0081] (1) The industrialized transparent indium tin oxide glass was repeatedly wiped with 95% pure isopropyl alcohol dipped in alcohol, and then ultrasonically cleaned with ultrapure water and 99% pure ethanol, with each step taking 13 minutes. Subsequently, it was placed in an oven and dried at 75°C for 3 hours; finally, the dried transparent indium tin oxide glass was placed in a UV ozone machine for surface treatment to improve the surface hydrophilicity, with a treatment time of 30 minutes.

[0082] (2) Spin-coating the PEDOT:PSS solution on the surface-modified transparent indium tin oxide glass at a spin-coating speed of 5000 rpm, thereby forming an anode interface modification layer on the surface of the transparent indium tin oxide glass.

[0083] (3) Weigh the corresponding masses of donor material PM6 and acceptor material BTP-eC9-4F according to the mass ratio of 1:1.2, place them in the same sample bottle, add chloroform solvent, stir at 50°C for 1 hour, and prepare a photosensitive active layer solution with a concentration of 15.4 mg / ml.

[0084] (4) Spin-coat the above-mentioned photosensitive active layer solution on the anode interface modification layer at a spin-coating speed of 2800 rpm, thereby forming a photosensitive active layer on the surface of the anode interface modification layer.

[0085] (5) Place the o-xylene solvent separately in a sample bottle in advance, and perform preheating treatment after sealing the sample bottle. The preheating temperature can be set to 50°C, 70°C, and 90°C, and the preheating time is set to 5 minutes.

[0086] (6) Place the photosensitive active layer at room temperature in the middle of a clean culture dish, then quickly add hot o-xylene solvent into the culture dish containing the photosensitive active layer, cover it with a lid, and form a closed environment. The treatment time of the photosensitive active layer in this environment can be set to 1 min, 3 min, and 5 min. The heated o-xylene solvent will evaporate to form steam, and when the photosensitive active layer comes into contact with the steam, a photosensitive active layer with a phase-separated nanostructure is formed.

[0087] (7) Spin-coating the PDI NN solution on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer.

[0088] (8) Use tweezers to scrape out the common anode and finally transfer it to a vapor deposition chamber. Under a high-pressure vacuum environment, thermal evaporation is used to complete the vapor deposition of the cathode electrode, thereby forming a metal electrode on the surface of the cathode interface modification layer, thereby obtaining an organic solar cell.

[0089] like Figure 6 As shown in Table 1, Figure 6 Table 1 shows the current density-voltage characteristic curves of organic solar cells prepared by solvent annealing post-treatment processes with different preheating temperatures under AM 1.5G standard simulated sunlight, and the test light irradiation intensity is 100mW / cm 2 Table 1 lists the photovoltaic performance parameters of the corresponding organic solar cells, including the open circuit voltage (V OC ), short-circuit current density (J SC ), fill factor (FF) and photoelectric conversion efficiency (PCE).

[0090] It can be seen from the above that when the photosensitive active layer treatment time is set to 5 min and the preheating temperature is 50 °C, the photovoltaic performance of the prepared organic solar cell is the best, V OC The FF and FF were 0.855V and 78.20%, respectively, and the PCE reached 18.56%. To further achieve the best effect of preheating solvent annealing, the treatment time of the photoactive layer was further optimized at the optimal preheating temperature (50°C) and set to 1min, 3min, and 5min, respectively. Figure 7 Table 1 shows the current density-voltage characteristic curves of organic solar cells prepared by preheating the solvent annealing treatment of the photosensitive active layer for different times under AM1.5G standard simulated sunlight, and the test light irradiation intensity is 100mW / cm 2Table 1 lists the photovoltaic performance parameters of the corresponding organic solar cells, including V OC , J SC , FF and PCE. It can be seen that when the photosensitive active layer treatment time is 3min and the preheating temperature is set to 50℃, the photovoltaic performance of the prepared organic solar cell reaches the best, V OC and FF are 0.856 V and 78.67% respectively, and the PCE reaches 18.64%.

[0091] Table 1

[0092]

[0093] Comparative Example 1

[0094] Step (6) in Example 1 was deleted, and step (5) was changed, while the rest remained unchanged. Step (5) is as follows:

[0095] (5) Place the spin-coated photosensitive active layer directly on a heating table for heating treatment. Set the temperature to 100° C., heat for 5 minutes and let stand for 5 minutes to achieve thermal annealing of the photosensitive active layer.

[0096] Comparative Example 2

[0097] The steps (5) and (6) in Example 1 were changed, and the rest remained unchanged. Steps (5) and (6) are as follows:

[0098] (5) Place the photosensitive active layer in a clean culture dish, then drop 40 μl of o-xylene solvent at room temperature into the dish, and cover it to form a closed environment.

[0099] (6) Place the entire culture dish on a heating table (i.e., the entire system of the photosensitive active layer and the o-xylene solvent is directly placed on the heating table), set the temperature to 90°C, and the heating time to 5 minutes.

[0100] It should be noted that in step (6) of Comparative Example 2, on the one hand, the PM6 molecules and BTP-eC9-4F molecules in the photosensitive active layer will accelerate orderly aggregation under the direct heating of the heating table; on the other hand, the o-xylene solvent at room temperature will form steam when heated. After the steam contacts the photosensitive active layer, it will further accelerate the heated PM6 molecules and BTP-eC9-4F molecules to form disordered motion, thereby improving the crystallinity of the film and increasing the phase separation, thereby causing excessive phase separation in the photosensitive active layer, making it impossible to achieve efficient dissociation, and increasing carrier recombination, thereby limiting the improvement of the efficiency of organic solar cells.

[0101] Table 2

[0102]

[0103] like Figure 8 As shown in Table 2, Figure 8 The current density-voltage characteristic curves of organic solar cells prepared by thermal annealing (Comparative Example 1) and solvent annealing (Comparative Example 2) under AM 1.5G standard simulated sunlight are shown. The test light irradiation intensity is 100mW / cm 2 Table 2 lists the photovoltaic performance parameters of organic solar cells prepared by thermal annealing (Comparative Example 1) and solvent annealing (Comparative Example 2) post-treatment processes, including V OC , J SC , FF and PCE.

[0104] As can be seen from the above, the J of the organic solar cell prepared in Comparative Example 1 is SC and FF showed lower performance, which were 28.02 mA / cm 2 and 70.76%, and the photoelectric conversion efficiency is 16.76%; the photovoltaic performance of the organic solar cell prepared in Comparative Example 2 is slightly improved compared with the organic solar cell prepared in Comparative Example 1, J SC and FF reached 27.64mA / cm 2 and 75.22%, and PCE increased to 17.57%. The organic solar cell prepared in Example 1 showed the best photovoltaic performance, V OC and FF reached 0.856mA / cm 2 and 78.67%, and PCE significantly increased to 18.64%. Therefore, it can be seen that the preheating solvent annealing process of the organic solar cell provided in the embodiment of the present application is feasible, can significantly improve the photovoltaic performance of the device, and has good universality. In addition, it can also avoid excessive phase separation of the photosensitive active layer caused by thermal annealing treatment, greatly simplifying the annealing process of the photosensitive active layer of the organic solar cell, and is suitable for the scenario where the photosensitive active layer is annealed with a high-boiling point solvent, which reduces the preparation cost of the organic solar cell, improves the efficiency of the organic solar cell, has a good application prospect, and is very suitable for industrial-grade preparation and production.

[0105] To further illustrate that the preheating solvent annealing process of the present invention has excellent universality for high boiling point solvents, we selected another high boiling point solvent (o-chlorobromobenzene) as the solvent for preheating solvent annealing, and its boiling point is 204° C. The specific implementation method is as follows:

[0106] Example 2

[0107] The steps (5) and (6) in Example 1 were changed, and the rest remained unchanged. Steps (5) and (6) are as follows:

[0108] (5) Place the o-chlorobromobenzene solvent separately in a sample bottle in advance, and heat it after sealing it. The heating temperature is set to 50° C. and the heating time is set to 5 min.

[0109] (6) Place the photosensitizing layer at room temperature in the middle of a clean culture dish, then quickly add hot o-chlorobromobenzene solvent into the culture dish containing the photosensitizing layer, cover it with a lid to form a closed environment, and treat the photosensitizing layer in this environment for 3 minutes; the heated o-chlorobromobenzene solvent will evaporate to form steam, and when the photosensitizing layer comes into contact with the steam, a photosensitizing layer with a phase-separated nanostructure is formed.

[0110] To better illustrate the effect of the preheating solvent annealing process, we also used high boiling point o-chlorobromobenzene solvent for the traditional solvent annealing process, as shown below:

[0111] Comparative Example 3

[0112] The steps (5) and (6) in Example 1 were changed, and the rest remained unchanged. Steps (5) and (6) are as follows:

[0113] (5) Place the photosensitive active layer in a clean culture dish, then drop 40 μl of o-chlorobromobenzene solvent at room temperature into the dish, and cover it to form a closed environment.

[0114] (6) Place the entire culture dish on a heating table (i.e., the entire system of the photosensitizing active layer and o-chlorobromobenzene solvent is directly placed on the heating table), set the temperature to 90°C, and the heating time to 5 minutes.

[0115] like Fig. 9 As shown in Table 3, Fig. 9 The current density-voltage characteristic curves of organic solar cells prepared by solvent annealing (Comparative Example 3) and preheating solvent annealing (Example 2) using o-chlorobromobenzene under AM 1.5G standard simulated sunlight are shown. The test light irradiation intensity is 100mW / cm 2 Table 3 lists the photovoltaic performance parameters of organic solar cells prepared by solvent annealing (Comparative Example 3) and preheating solvent annealing (Example 2) using o-chlorobromobenzene, including V OC , J SC , FF and PCE.

[0116] Table 3

[0117]

[0118] As can be seen from the above, when o-chlorobromobenzene is used as the processing solvent, the V OCThe V and FF performances are relatively low, which are 0.849 V and 76.36% respectively, and the photoelectric conversion efficiency is 17.85%; while the photovoltaic performance of the organic solar cell prepared by the preheating solvent annealing provided by the present invention is the best, V OC and FF are 0.856V and 77.59% respectively, and PCE reaches 18.45%. This shows that the preheating solvent annealing process of the organic solar cell provided in the embodiment of the present application has good universality for high boiling point solvents, can significantly improve the photovoltaic performance of the device, and can also avoid excessive phase separation of the photosensitive active layer caused by thermal annealing treatment, greatly simplifying the solvent annealing process of the photosensitive active layer of the organic solar cell.

[0119] An embodiment of the present application further provides an organic solar cell, which is prepared by using the method for preparing a solar cell provided by any of the above embodiments.

[0120] Among them, the specific method of preparing the organic solar cell can refer to the corresponding embodiment recorded in the specification of this application, and this embodiment will not be repeated here. The photosensitive active layer of the organic solar cell provided in the embodiment of this application has a suitable phase separation size and crystallization domain, which is conducive to achieving effective exciton dissociation and rapid charge transfer, and the organic solar cell has high photovoltaic performance, low manufacturing cost, and can be prepared on a large scale, and has a good prospect for industrial application.

[0121] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing an organic solar cell, characterized in that: The method comprises: Providing a conductive substrate, and spin-coating an anode interface modification layer solution on the conductive substrate to form an anode interface modification layer on the surface of the conductive substrate; Preparing a photosensitive active layer solution, and spin-coating the photosensitive active layer solution on the anode interface modification layer to form a photosensitive active layer on the surface of the anode interface modification layer; Preheating the first solvent so that the first solvent can generate steam, wherein the boiling point of the first solvent is higher than 120° C.; placing the photosensitive active layer at room temperature and the first solvent after heating in the same closed environment, so that the vapor generated by the first solvent dissolves the material in the photosensitive active layer to form a photosensitive active layer with a phase-separated nanostructure; Spin coating a cathode interface modification layer solution on the photosensitive active layer to form a cathode interface modification layer on the surface of the photosensitive active layer; A metal electrode is formed on the surface of the cathode interface modification layer.

2. The method according to claim 1, characterized in that The temperature of the preheating treatment is 50-90° C.; and / or the time of the preheating treatment is 1-10 min.

3. The method according to claim 1, characterized in that Placing the photosensitive active layer at room temperature and the first solvent after heating in the same closed environment so that the vapor generated by the first solvent dissolves the material in the photosensitive active layer to form a photosensitive active layer with a phase-separated nanostructure includes: The photosensitive active layer at room temperature and the first solvent after heating are placed in the same closed environment and left to stand for 1-5 minutes. After the photosensitive active layer at room temperature contacts the steam generated by the first solvent, the material in the photosensitive active layer will be redissolved, promoting further movement of the donor molecules and the acceptor molecules in the photosensitive active layer, thereby forming a photosensitive active layer with a phase-separated nanostructure.

4. The method according to claim 1, characterized in that: After spin coating the anode interface modification layer solution on the conductive substrate to form the anode interface modification layer on the surface of the conductive substrate, the method further comprises: The anode interface modification layer is subjected to thermal annealing treatment, wherein the temperature of the thermal annealing treatment is 100-160° C. and the time of the thermal annealing treatment is 10-30 minutes.

5. The method according to claim 1, characterized in that The method of preparing the photosensitive active layer solution comprises: Providing a donor material and an acceptor material, wherein the mass ratio of the donor material to the acceptor material is 1:(0.5-4); The donor material and the acceptor material are dissolved in a second solvent to prepare a photosensitive active layer solution, wherein the concentration of the photosensitive active layer solution is 8-16 mg / ml.

6. The method according to claim 5, characterized in that The donor material is PM6, and the acceptor material is BTP-eC9-4F.

7. The method according to claim 1, characterized in that The step of forming a metal electrode on the surface of the cathode interface modification layer comprises: Dissolving metals using thermal evaporation equipment; Based on the preset vacuum condition, the dissolved metal is evaporated onto the cathode interface modification layer to form a metal electrode on the surface of the cathode interface modification layer.

8. The method according to any one of claims 1 to 7, characterized in that: The thickness of the anode interface modification layer is 5-40nm; and / or the thickness of the photosensitive active layer is 40-300nm; and / or the thickness of the cathode interface modification layer is 5-30nm; and / or the thickness of the metal electrode is 40-200nm.

9. The method according to any one of claims 1 to 7, characterized in that: The first solvent includes o-xylene solvent or o-chlorobromobenzene.

10. An organic solar cell, characterized in that: The organic solar cell is prepared by using the method for preparing an organic solar cell according to any one of claims 1 to 9.

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