An organic solar cell and its preparation method, and a photovoltaic module.

Abstract

This invention provides an organic solar cell, its fabrication method, and a photovoltaic module, relating to the field of organic solar cell technology. The method includes: depositing a first solution on a substrate and drying it to form a first material absorber layer; the first solution includes a first material and a first solvent; depositing a second solution on the first material absorber layer and drying it to form a mixed absorber layer; the second solution includes a second material, a second solvent, and the first material; depositing a third solution on the mixed absorber layer and drying it to form a second material absorber layer; the third solution includes a third solvent and a second material. The first and second material absorber layers obtained by this invention have high crystallinity and good morphological uniformity, which is beneficial for charge migration towards the electrode direction. The formed mixed absorber layer has more interfaces between the first and second materials, which is beneficial for exciton separation and the generation of free charges. Simultaneously, the fabrication method is simple and allows for precise control.

Description

Technical Field

[0001] This invention relates to the field of organic solar cell technology, and in particular to an organic solar cell, its preparation method, and a photovoltaic module. Background Technology

[0002] Organic solar cells have enormous application potential due to their lightweight nature and the ability to achieve translucency and color. In particular, pin-type organic solar cells have attracted more attention because they theoretically possess excellent donor-acceptor interfaces and high crystallinity.

[0003] For pin-type organic solar cells, their morphology significantly affects their performance.

[0004] However, existing methods for fabricating pin-type organic solar cells have poor morphology control, which affects their performance. Summary of the Invention

[0005] This invention provides an organic solar cell and its preparation method, as well as a photovoltaic module, aiming to solve the problem that existing organic solar cell preparation methods have poor morphology control, which affects their performance.

[0006] A first aspect of the present invention provides a method for preparing an organic solar cell, comprising:

[0007] A substrate is provided, a first solution is disposed on the substrate, and dried to form a first material absorption layer; the first solution includes a first material and a first solvent;

[0008] A second solution is disposed on the first material absorption layer and dried to form a mixed absorption layer; the second solution includes a second material, a second solvent, and the first material; the first material is one of an electron donor material and an electron acceptor material, and the second material is another of an electron donor material and an electron acceptor material;

[0009] A third solution is disposed on the mixed absorption layer and dried to form a second material absorption layer; the third solution comprises a third solvent and the second material.

[0010] In this invention, the first material absorption layer is obtained by evaporating the first solvent in the first solution, the mixed absorption layer is obtained by evaporating the second solvent in the second solution, and the third material absorption layer is obtained by evaporating the third solvent in the third solution. All three layers are prepared using a solvent method. The solvent method provides a suitable preparation environment for the formation of each layer. The resulting first material absorption layer has high crystallinity and a uniform morphology, which is beneficial for charge migration towards the electrode. Similarly, the resulting second material absorption layer also has high crystallinity and a uniform morphology, which is beneficial for charge migration towards the electrode. The first and second materials are thoroughly mixed in the second solvent, resulting in a more uniform mixture of the first and second materials in the mixed absorption layer. This mixture has more interfaces between the first and second materials, which is beneficial for exciton separation and the generation of free charges. Furthermore, this preparation method is simple and allows for precise control.

[0011] Optionally, the solubility of the second solvent in the first material, the solubility of the second solvent in the second material, the solubility of the first solvent in the first material, and the solubility of the third solvent in the second material are all greater than the solubility of the third solvent in the first material; and the boiling point of the first solvent and the boiling point of the third solvent are both greater than or equal to the boiling point of the second solvent.

[0012] In this embodiment of the invention, the first solvent has a high solubility for the first material, resulting in a first material absorber layer with high crystallinity and good morphological uniformity, which is beneficial for charge migration towards the electrode. Furthermore, the high solubility of the first solvent for the first material reduces aggregates and film splitting during the formation of the first material absorber layer, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. The third solvent has a high solubility for the second material, resulting in a second material absorber layer with high crystallinity and good morphological uniformity, which is also beneficial for charge migration towards the electrode. Furthermore, the high solubility of the third solvent for the second material reduces aggregates and film splitting during the formation of the second material absorber layer, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. The second solvent has good solubility for the first material, enabling the formation of a well-morphological contact interface between the mixed absorber layer and the first material absorber layer. The interface roughness is low, which reduces the contact resistance between the mixed absorber layer and the first material absorber layer. The second solvent also has good solubility for the second material, enabling the formation of a well-morphological contact interface between the mixed absorber layer and the second material absorber layer. The interface roughness is low, which reduces the contact resistance between the mixed absorber layer and the second material absorber layer. The second solvent exhibits good solubility in both the first and second materials, resulting in a relatively uniform mixture of the two materials in the formed hybrid absorber layer. This creates more interfaces between the first and second materials, facilitating exciton separation and the generation of free charges. Furthermore, the good solubility of the second solvent in both materials ensures that the clusters of the first and second materials in the hybrid absorber layer are of similar and relatively small size, which is beneficial for exciton transport to the interface between the first and second material clusters for dissociation and the generation of free charges. Simultaneously, the second solvent has a lower boiling point, allowing for a shorter drying time and reducing damage to the first material absorber layer during drying, thus maintaining its structural integrity and improving the performance of the organic solar cell. Even if a third solvent permeates the first material absorber layer during the preparation of the second material absorber layer, the third solvent is almost insoluble or has near-zero solubility in the first material, preventing damage to the structure and morphology of the first material absorber layer and maintaining its structural integrity, further enhancing the performance of the organic solar cell. Moreover, this preparation method is simple and allows for precise control.

[0013] Optional, HD1 is the Hansen distance between the first solvent and the first material, and R1 is the radius of the Hansen sphere of the first material;

[0014] HD21 is the Hansen distance between the second solvent and the first material; HD22 is the Hansen distance between the second solvent and the second material, and R2 is the radius of the Hansen sphere of the second material;

[0015] HD3 is the Hansen distance between the third solvent and the second material;

[0016] HD31 is the Hansen distance between the third solvent and the first material.

[0017] Optionally, the boiling point of the first solvent is less than or equal to 185°C;

[0018] And / or, the boiling point of the third solvent is less than or equal to 185°C.

[0019] Optionally, the difference between the solubility of the second solvent in the first material and the solubility of the second solvent in the second material is less than a preset value.

[0020] Optionally, the boiling point of the second solvent is less than or equal to 100°C.

[0021] Optionally, the step of setting the first solution on the substrate and drying it includes:

[0022] A first solution is disposed on the substrate and dried in a first atmosphere; in the first atmosphere, the volume content of the gaseous first solvent is less than or equal to 30% of the total volume of the first atmosphere.

[0023] And / or, the step of applying a second solution to the first material absorbent layer and drying it includes:

[0024] A second solution is disposed on the first material absorption layer and dried in a second atmosphere; in the second atmosphere, the volume content of the gaseous second solvent is less than or equal to 30% of the total volume of the second atmosphere.

[0025] And / or, the provision of a third solution on the mixed absorbent layer and drying includes:

[0026] A third solution is disposed on the mixed absorption layer and dried in a third atmosphere; in the third atmosphere, the volume content of the gaseous second solvent is less than or equal to 30% of the total volume of the second atmosphere.

[0027] Optionally, the drying includes at least one of vacuum drying and heat drying;

[0028] During the drying process, the ambient temperature is between 20°C and 170°C.

[0029] Optionally, before setting the first solution on the substrate and drying it, the method further includes:

[0030] HD1 is determined based on the dispersive forces of the first material molecules, the dispersive forces of the first solvent molecules, the dipole forces of the first material molecules, the dipole forces of the first solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the first solvent molecules.

[0031] Before applying the second solution to the first material absorbent layer and drying it, the method further includes:

[0032] HD21 is determined based on the dispersive forces of the first material molecules, the dispersive forces of the second solvent molecules, the dipole forces of the first material molecules, the dipole forces of the second solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the second solvent molecules.

[0033] HD22 is determined based on the dispersive forces of the second material molecules, the dispersive forces of the second solvent molecules, the dipole forces of the second material molecules, the dipole forces of the second solvent molecules, the hydrogen bonding forces of the second material molecules, and the hydrogen bonding forces of the second solvent molecules.

[0034] Before the third solution is applied to the mixed absorption layer and dried, the method further includes:

[0035] HD31 is determined based on the dispersive forces of the first material molecules, the dispersive forces of the third solvent molecules, the dipole forces of the first material molecules, the dipole forces of the third solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the third solvent molecules.

[0036] HD3 is determined based on the dispersive forces of the second material molecules, the dispersive forces of the third solvent molecules, the dipole forces of the second material molecules, the dipole forces of the third solvent molecules, the hydrogen bonding forces of the second material molecules, and the hydrogen bonding forces of the third solvent molecules.

[0037] Optionally, the step of setting the first solution on the substrate includes: setting the first solution on the substrate using at least one of spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing;

[0038] And / or, the provision of the second solution on the first material absorption layer includes: using at least one of spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing to provide the second solution on the first material absorption layer;

[0039] And / or, the provision of the third solution on the mixed absorption layer includes: using at least one of spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing to provide the third solution on the mixed absorption layer.

[0040] Optionally, the step of setting the first solution on the substrate and drying it includes:

[0041] A first electrode is disposed on the substrate;

[0042] A first transport layer is disposed on the first electrode;

[0043] A first solution is applied to the first transport layer and then dried.

[0044] After forming the second material absorption layer, the method further includes:

[0045] A second transport layer is disposed on the second material absorption layer;

[0046] A second electrode is formed on the second transport layer.

[0047] Optionally, the step of setting the first transport layer on the first electrode includes: setting the first transport layer on the first electrode by at least one of spin coating, blade coating, slot coating, roll-to-roll coating, inkjet printing, and vacuum evaporation.

[0048] The provision of a second transport layer on the second material absorption layer includes:

[0049] A second transport layer is formed on the second material absorption layer by employing at least one of spin coating, blade coating, slot coating, roll-to-roll coating, inkjet printing, and vacuum evaporation.

[0050] A second aspect of the present invention provides an organic solar cell, comprising: a first material absorber layer, a second material absorber layer located above the first material absorber layer, and a mixed absorber layer located between the first material absorber layer and the second material absorber layer; wherein the first material absorber layer is formed by evaporating a first solvent in a first solution containing a first material; the second material absorber layer is formed by evaporating a third solvent in a third solution containing a second material; the mixed absorber layer is formed by evaporating a second solvent in a second solution containing the first material and the second material; wherein the first material is one of an electron donor material and an electron acceptor material, and the second material is another of an electron donor material and an electron acceptor material.

[0051] Optionally, the root mean square surface roughness of the hybrid absorption layer is less than or equal to 10 nm.

[0052] Optionally, the hybrid absorption layer includes: electron donor clusters and electron acceptor clusters, wherein the size of the electron donor clusters is less than or equal to 20 nm; and the size of the electron acceptor clusters is less than or equal to 20 nm.

[0053] Optionally, the size of the electron donor cluster is 3 nm to 10 nm; the size of the electron acceptor cluster is 3 nm to 10 nm.

[0054] Optionally, the size of the electron donor cluster is 5 nm to 10 nm; the size of the electron acceptor cluster is 5 nm to 10 nm.

[0055] Optionally, the total thickness of the first material absorption layer, the mixed absorption layer, and the second material absorption layer is greater than or equal to 100 nm; the direction of the thickness is parallel to the setting direction of the first material absorption layer and the mixed absorption layer.

[0056] Optionally, the thickness of the first material absorption layer is 40 nm to 170 nm;

[0057] The thickness of the hybrid absorption layer is 10 nm to 60 nm;

[0058] The thickness of the second material absorption layer is 40 nm to 170 nm; the direction of the thickness is parallel to the direction in which the first material absorption layer and the mixed absorption layer are disposed.

[0059] Optionally, the organic solar cell further includes a first electrode located on the side of the first material absorber layer away from the hybrid absorber layer, and a first transport layer, wherein the first transport layer is located between the first electrode and the first material absorber layer, and the thickness of the first transport layer is 5 nm to 50 nm.

[0060] The organic solar cell further includes a second transport layer located on the side of the second material absorber layer away from the first electrode, and the thickness of the second transport layer is 5 nm to 50 nm.

[0061] A third aspect of the present invention provides a photovoltaic module comprising: any of the aforementioned organic solar cells.

[0062] The aforementioned organic solar cells and photovoltaic modules all have the same or similar beneficial effects as the aforementioned organic solar cell preparation methods, and will not be repeated here to avoid repetition. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 A flowchart illustrating the steps of a method for preparing an organic solar cell according to an embodiment of the present invention is shown;

[0065] Figure 2 A schematic diagram of the structure of an organic solar cell according to an embodiment of the present invention is shown;

[0066] Figure 3 A schematic diagram of the structure of the organic absorber layer in an organic solar cell according to an embodiment of the present invention is shown.

[0067] Explanation of the attached drawing numbers:

[0068] 1-First electrode, 2-First transport layer, 3-Organic absorber layer, 4-Second transport layer, 5-Second electrode, 31-First material absorber layer, 32-Second material absorber layer, 33-Mixed absorber layer. Detailed Implementation

[0069] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0070] Organic solar cells have developed rapidly in recent years. Currently, the efficiency of bulk heterojunction (BHJ) organic solar cells has reached 19%, and the efficiency of organic-organic tandem solar cells has exceeded 20%. Their efficiency has met the needs of commercialization, and there is still room for further improvement.

[0071] Figure 1 A flowchart illustrating the steps of a method for preparing an organic solar cell according to an embodiment of the present invention is shown. Figure 2 A schematic diagram of the structure of an organic solar cell according to an embodiment of the present invention is shown. Figure 3 A schematic diagram of the structure of the organic absorber layer in an organic solar cell according to an embodiment of the present invention is shown.

[0072] Reference Figure 1 As shown, the preparation method includes the following steps:

[0073] Step 101: Provide a substrate, apply a first solution on the substrate, and dry it to form a first material absorption layer; the first solution includes a first material and a first solvent.

[0074] The substrate material can be transparent conductive glass, etc., and the specific material of the substrate is not limited. It should be noted that a first electrode 1 can be disposed on the substrate, and then a first solution is disposed on the first electrode 1 and dried to form a first material absorption layer 31. Alternatively, the substrate may not have a first electrode. After the rest of the organic solar cell is fabricated, the substrate is removed, and the first electrode 1 is disposed in the original position of the substrate to form an organic solar cell.

[0075] A first solution is applied to a substrate and dried to form a first material absorption layer 31. This first solution comprises a first material and a first solvent; specifically, the first solvent dissolves the first material to form the first solution. For the first solution, the first solvent needs to provide good solubility for the first material, resulting in strong intermolecular forces between the molecules of the first material and the first solvent. In the first solution, the first material can be completely dissolved in the first solvent without forming clustered precipitates, and the first solution maintains a stable and homogeneous state. The first solution can be applied to the substrate by coating, etc., and dried by vacuum drying and / or heat drying, etc. Optionally, the first solvent provides good solubility for the first material, allowing the first material to gradually form a supersaturated solvent during the wet film drying process, gradually precipitating out and promoting crystal growth and increasing size. Conversely, if the first solvent has low solubility for the first material, the precipitation rate of the first material increases, which is detrimental to crystal growth and may even lead to large-sized precipitates. During the drying process, the first solvent evaporates, and the main component of the formed first material absorption layer 31 is the first material. The first material absorption layer 31 can be either an electron donor cluster layer or an electron acceptor cluster layer. Alternatively, the first material absorption layer 31 can be either an electron donor p-layer or an electron acceptor n-layer. Alternatively, the first material can be either an electron donor material or an electron acceptor material; that is, whether the first material is a pure substance or a mixture, all materials in the first material are electron donor materials, or all materials in the first material are electron acceptor materials.

[0076] Optional, such as Figure 2 As shown, the thickness d3 of the first material absorption layer 31 can be from 40 nm to 170 nm. The direction of the thickness of the first material absorption layer 31 is parallel to... Figure 2 The first material absorption layer 31 and the mixed absorption layer 32 are arranged in parallel directions. The thickness direction mentioned throughout the text follows the same definition.

[0077] Step 102: A second solution is disposed on the first material absorption layer and dried to form a mixed absorption layer; the second solution includes a second material, a second solvent, and the first material; the first material is one of an electron donor material and an electron acceptor material, and the second material is another of an electron donor material and an electron acceptor material.

[0078] A second solution is applied to the first material absorption layer 31 and then dried to form a mixed absorption layer 33. The second solution comprises a second material, a second solvent, and the first material. The second solvent dissolves both the first and second materials to obtain the second solution. The second solvent has good solubility for both the first and second materials, the second solution is stable, and there are strong interactions between the molecules of the second solvent and the molecules of both the first and second materials. Applying the second solution to the first material absorption layer 31 allows it to wet the first material absorption layer 31. Because the second solvent can dissolve the first material, it allows for appropriate miscibility at the interface between the first absorption layer 31 and the mixed absorption layer 33, optimizing recrystallization. This increases the interfacial contact between the first material absorption layer 31 and the mixed absorption layer 33, reduces interfacial resistance and defects, and is beneficial for exciton and charge transport. Optionally, the second solvent has a low boiling point, is easily volatile, and will not completely destroy the structure of the first material absorption layer 31. The method of applying the second solution to the first material absorption layer 31 can be coating, etc., and the specific method of application is not limited. The drying method can be vacuum drying and / or heat drying, etc.

[0079] During the drying process, the second solvent evaporates; therefore, the main components of the mixed absorber layer 33 are the first material and the second material. The first material is either an electron donor material or an electron acceptor material, and the second material is either an electron donor material or an electron acceptor material. That is, if the first material is an electron donor material, then the second material is an electron acceptor material. If the first material is an electron acceptor material, then the second material is an electron donor material. In other words, whether the second material is a pure substance or a mixture, all materials in the second material are electron donor materials, or all materials in the second material are electron acceptor materials. Optionally, the thickness d2 of the mixed absorber layer 33 is from 10 nm to 60 nm.

[0080] Step 103: A third solution is applied to the mixed absorption layer and dried to form a second material absorption layer; the third solution includes a third solvent and the second material.

[0081] A third solution is applied to the mixed absorption layer 33 and dried to form a second material absorption layer 32. The third solution comprises a third solvent and a second material, obtained by dissolving the second material in the third solvent. The third solvent effectively dissolves the second material, providing favorable growth conditions for its crystallization. Simultaneously, the third solution wets the mixed absorption layer 33. Since the third solvent dissolves the second material, a dissolution-recrystallization process occurs in the second material within the mixed absorption layer 33, optimizing the interface between the mixed absorption layer 33 and the second material absorption layer 32 and reducing interfacial contact. Furthermore, the third solvent does not dissolve the first material; therefore, even if the third solvent wets the first material absorption layer 31 during the preparation of the second material absorption layer 32, it will not damage the structure and morphology of the first material absorption layer 31. The third solution can be applied by coating or similar methods. Drying methods can also include vacuum drying and / or heat drying, with no specific limitations on the drying method. During the drying process, the third solvent evaporates; therefore, the main component of the second material absorption layer 32 is the second material. Therefore, in the organic solar cell, one of the first material absorption layer 31 and the second material absorption layer 32 is a p layer and the other is an n layer, and the mixed absorption layer 33 exists as an i layer.

[0082] Optionally, the solubility of the second solvent in the first material, the solubility of the second solvent in the second material, the solubility of the first solvent in the first material, and the solubility of the third solvent in the second material are all greater than the solubility of the third solvent in the first material. More precisely, the third solvent is almost insoluble in the first material or its solubility is close to 0, while the solubility of the second solvent in the first material, the solubility of the second solvent in the second material, the solubility of the first solvent in the first material, and the solubility of the third solvent in the second material are all relatively large. Among these, the relatively large solubility of the first solvent in the first material indicates a strong intermolecular force between the first solvent and the first material, which can promote the growth of organic crystals rather than simple precipitation and aggregation. The resulting first material absorption layer 31 has high crystallinity, good uniformity of morphology, low roughness, and a smoother or flatter surface. Free charges have a higher mobility and less energy loss in the uniform and highly crystalline film layer, which is conducive to charge migration towards the electrode direction. Furthermore, the relatively large solubility of the first solvent in the first material reduces aggregates and film splitting during the formation of the first material absorption layer 31, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. Meanwhile, the smoother surface of the first material absorber layer 31 facilitates the fabrication of subsequent layers. The third solvent has a high solubility for the second material, resulting in a second material absorber layer 32 with high crystallinity and uniform morphology. This promotes charge migration towards the electrode. Furthermore, the high solubility of the third solvent reduces aggregates and film splitting during the formation of the second material absorber layer 32, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. The good solubility of the second solvent for the first material allows for the formation of a well-morphologically sound contact interface between the mixed absorber layer 33 and the first material absorber layer 31. The lower interface roughness reduces the contact resistance between the mixed absorber layer 33 and the first material absorber layer 31. The good solubility of the second solvent for the second material allows for the formation of a well-morphologically sound contact interface between the mixed absorber layer 33 and the second material absorber layer 32. The lower interface roughness reduces the contact resistance between the mixed absorber layer 33 and the second material absorber layer 32. The second solvent has good solubility for both the first and second materials, resulting in a relatively uniform mixture of the first and second materials in the formed mixed absorption layer. The mixed absorption layer 33 has more interfaces between the first and second materials, which is beneficial for exciton separation to generate free charges. Moreover, the second solvent has good solubility for both the first and second materials, and the clusters of the first and second materials in the mixed absorption layer 33 are of similar size and relatively small, which is beneficial for exciton transport to the interface between the clusters of the first and second materials for dissociation and generation of free charges.During the preparation of the second material absorber layer 32, even if the third solvent wets the first material absorber layer 31, the third solvent will not damage the structure and morphology of the first material absorber layer 31 because the third solvent is almost insoluble or has a solubility close to 0. This maintains the structural integrity of the first material absorber layer 31 and is beneficial to improving the performance of organic solar cells. At the same time, this preparation method is simple and facilitates precise control.

[0083] Optionally, the boiling points of the first solvent and the third solvent are both greater than or equal to the boiling point of the second solvent. That is, the boiling point of the second solvent is lower, resulting in a shorter drying time during the drying process. This reduces the damage to the first material absorber layer 31 caused by drying the second solvent, maintains the structural integrity of the first material absorber layer 31, and is beneficial to improving the performance of the organic solar cell. It should be noted that the specific amount by which the boiling points of the first solvent and the third solvent are greater than the boiling point of the second solvent is not specifically limited.

[0084] Optionally, setting the first solution in step 101 may include: using at least one of the following solution methods, such as spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing, to set the first solution on the substrate. The above-mentioned methods for setting the first solution are mature and the quality of the set first solution is good.

[0085] Optionally, setting the second solution in step 102 may include: using at least one of the following solution methods, such as spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing, to set the second solution on the first material absorption layer 31. The above-mentioned methods for setting the second solution are mature and the quality of the set second solution is good.

[0086] Optionally, setting the third solution in step 103 may include: using at least one of the following solution methods, such as spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing, to set the third solution on the mixed absorption layer 33. The above-mentioned methods for setting the third solution are mature and the quality of the set third solution is good.

[0087] Optionally, during the drying process in steps 101, 102, and 103, the ambient temperature is between 20°C and 170°C. A suitable ambient temperature has minimal impact on structural integrity. For example, in step 101, the ambient temperature during the drying process can be 20°C, 40°C, 50°C, 60°C, 80°C, 90°C, 100°C, 110°C, 120°C, 150°C, or 170°C.

[0088] Optionally, the drying in step 101 can be: placing a first solution on a substrate and drying it in a first atmosphere, wherein the volume content of the gaseous first solvent in the first atmosphere is less than or equal to 30% of the total volume of the first atmosphere, which facilitates the evaporation of the first solvent and can shorten the drying time. For example, in the drying first atmosphere in step 101, the volume content of the gaseous first solvent is 30%, 28%, 25%, 20%, 18%, or 15% of the total volume of the first atmosphere.

[0089] Optionally, the drying in step 102 can be: placing a second solution on the first material absorption layer 31 and drying in a second atmosphere, wherein the volume content of the gaseous second solvent in the second atmosphere is less than or equal to 30% of the total volume of the second atmosphere. This second atmosphere facilitates the evaporation of the second solvent and can shorten the drying time. For example, in the drying second atmosphere in step 102, the volume content of the gaseous second solvent is 30%, 27%, 24%, 20%, 17%, or 16% of the total volume of the second atmosphere.

[0090] Optionally, the drying in step 103 can be: placing a third solution on the mixed absorption layer 33 and drying in a third atmosphere, wherein the volume content of the gaseous third solvent in the third atmosphere is less than or equal to 30% of the total volume of the third atmosphere. This third atmosphere is conducive to the volatilization of the third solvent and can shorten the drying time. For example, in the drying third atmosphere in step 103, the volume content of the gaseous third solvent is 30%, 25%, 24%, 20%, 17%, or 15% of the total volume of the third atmosphere.

[0091] Optional, such as Figure 2 As shown, step 101 may include: setting a first electrode 1 on a substrate, then setting a first transport layer 2 on the first electrode 1, setting a first solution on the first transport layer 2, and drying. That is, the organic solar cell also includes a first electrode 1 and a first transport layer 2 located on the side of the first material absorber layer 31 away from the mixed absorber layer 33. The first transport layer 2 is located between the first electrode 1 and the first material absorber layer 31, and can cooperate with the first material absorber layer 31 to improve the exciton or charge transport efficiency. The thickness d4 of the first transport layer 2 can be from 5 nm to 50 nm.

[0092] Optionally, setting the first transport layer 2 may include: using at least one of the following methods: spin coating, blade coating, slot coating, roll-to-roll coating, inkjet printing, vacuum evaporation, etc., to set the first transport layer 2 on the first electrode 1. The method of setting the first transport layer 2 is flexible and the process is mature.

[0093] Optional, such as Figure 2 As shown, after step 103, the method may further include: forming a second transport layer 4 on the second material absorber layer 32; that is, the organic solar cell further includes a second transport layer 4 and a second electrode 5 located on the side of the second material absorber layer 32 away from the first electrode 1. The second transport layer 4 can cooperate with the second material absorber layer 32 to improve the exciton or charge transport efficiency. The thickness d5 of the second transport layer 4 can be from 5 nm to 50 nm. A second electrode 5 is formed on the second transport layer 4, and the material of the second electrode 5 can be silver or aluminum. The thickness d6 of the second electrode 5 can be from 50 nm to 200 nm.

[0094] Optionally, setting the second transport layer 4 may include: using at least one of the following methods: spin coating, blade coating, slot coating, roll-to-roll coating, inkjet printing, vacuum evaporation, etc., to set the second transport layer 4 on the second material absorption layer 32. The method of setting the second transport layer 4 is flexible and the process is mature.

[0095] Figure 2 The working principle of the organic solar cell shown is as follows: the organic material absorber layer 3 absorbs photons, exciting electron-hole exciton pairs. These pairs separate at the electron donor-electron acceptor interface in the mixed absorber layer 33. The exciton pairs then transport through the p-type layer, or between the first and second material absorber layers 31 and 32. Free charges are then transported through the mixed absorber layer 33 to the first and second material absorber layers 31 and finally to the electrode. Therefore, both the first and second material absorber layers 31 and 32 need to provide good lattice morphology to reduce energy loss during exciton and charge transport. The mixed absorber layer 33 needs to provide sufficient p / n interfaces to facilitate exciton separation and generate free charges. The interfaces between the first and second material absorber layers 31 and 33, and between the second and third material absorber layers 32 and 33, need to have well-formed contact interfaces to reduce interlayer contact resistance.

[0096] Optionally, the boiling point of the second solvent is less than or equal to 100°C, meaning the second solvent has good volatility. Before the second solution is completely dried, only a small amount of the second solvent permeates into the first material absorption layer 31. This can effectively improve the interface morphology between the first material absorption layer 31 and the mixed absorption layer 33, reduce the interfacial contact resistance, and at the same time, avoid damaging the structure of the first material absorption layer 31. For example, the boiling point of the second solvent is 100°C, or 95°C, or 90°C, or 88°C, or 80°C, or 76°C, or 70°C.

[0097] The Hansen solubility (HS) theory states that the ratio of the Hansen distance (HD) between the solvent and solute to the radius (R) of the Hansen sphere of the solute is... A value greater than 1 indicates that the solvent cannot dissolve the solute; the ratio of the two is... A value of 1 indicates the limiting solubility of the solute in the solvent at this point, meaning the solute and solvent are in a mixed state of slight solubility and insolubility. The ratio of the two is... A value less than 1 indicates that the solvent can dissolve the solute, and The smaller the value, the better the solvent's solubility of the solute.

[0098] Optional, HD1 is the Hansen distance between the first solvent and the first material, and R1 is the Hansen sphere radius of the first material. According to the Hansen solubility theory, the first solvent has a high solubility for the first material, resulting in a higher crystallinity and better morphological uniformity in the first material absorber layer 31. This is beneficial for charge migration towards the electrode. Furthermore, the high solubility of the first solvent for the first material reduces aggregates and film splitting during the formation of the first material absorber layer 31, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. The Hansen sphere radius R1 of the first material can be obtained based on the type of first material.

[0099] For example, It can be 0.85, or 0.83, or 0.80, or 0.77, or 0.72, or 0.70, or 0.64, or 0.50.

[0100] It should be noted that if there are more than one type of first material, the Hansen distance between the first solvent and each first material, as well as the Hansen sphere radius of that first material, can be obtained separately. Then, the Hansen distance between the first solvent and that first material can be divided by the Hansen sphere radius of that first material to obtain the corresponding ratio. Next, the mole fraction of that first material in all first materials can be multiplied by the corresponding ratio to obtain the contribution ratio of that first material. Finally, the contribution ratios of all first materials can be summed to obtain the value of the first material across multiple types.

[0101] Optionally, prior to step 101, the method may further include: based on the dispersive force δ of the first material molecule. D2 The dispersive force δ of the first solvent molecule D1 The dipole force δ of the first material molecule p2 The dipole force δ of the first solvent molecule p1 The hydrogen bonding force δ of the first material moleculeH2 The hydrogen bonding force δ of the first solvent molecule H1 To determine HD1, more specifically, according to Hansen's solubility theory, the solubility of the first solvent and the first material can be calculated using Formula 1: HD1 2 =4(δ) D1 -δ D2 ) 2 +(δ P1 -δ P2 ) 2 +(δ H1 -δ H2 ) 2 After obtaining HD1 2 HD1 can then be obtained by taking the formula. The Hansen distance HD1 obtained from this method is more accurate between the first solvent and the first material.

[0102] It should be noted that the dispersion force δ of the first material molecules D2 The dispersive force δ of the first solvent molecule D1 The dipole force δ of the first material molecule p2 The dipole force δ of the first solvent molecule p1 The hydrogen bonding force δ of the first material molecule H2 The hydrogen bonding force δ of the first solvent molecule H1 These six parameters can be obtained through the following four methods: 1. Data can be obtained experimentally by mixing a first material with different first solvents. Based on their respective solubility, each first solvent is numbered from 0 to 2, where 0 is an immiscible solvent, 1 is a completely miscible solvent, and 2 is a partially miscible solvent. The solubility can be further subdivided according to the degree of solubility. The larger the value, the lower the degree of miscibility. The data is then imported into the HSPiP software (https: / / www.hansen-solubility.com / HSPiP / ) for calculation; 2. The parameters can be obtained from the HSPiP database based on the first material and the first solvent; 3. The parameters can be obtained through Y-MB simulation (http: / / www / pirika.com / NewHP / Y-MB / Y-MB.com); 4. The parameters can be calculated using the group contribution method.

[0103] HD21 is the Hansen distance between the second solvent and the first material, and R1 is the radius of the Hansen sphere of the first material. According to the Hansen solubility theory, the second solvent has good solubility for the first material, which enables the formation of a well-shaped contact interface between the mixed absorption layer 33 and the first material absorption layer 31. The roughness of the interface is small, which can reduce the contact resistance between the mixed absorption layer 33 and the first material absorption layer 31.

[0104] For example, It can be 0.85, or 0.81, or 0.80, or 0.75, or 0.73, or 0.70, or 0.65, or 0.62.

[0105] It should be noted that if the number of types of the first material is greater than one, the combination of multiple types of the first material and the second solvent... Compared with the aforementioned various types of the first material and the first solvent The determination method is similar, and will not be repeated here to avoid repetition.

[0106] HD22 is the Hansen distance between the second solvent and the second material, and R2 is the Hansen sphere radius of the second material. According to the Hansen solubility theory, the second solvent has good solubility for the second material, enabling the formation of a well-formed contact interface between the mixed absorption layer 33 and the second material absorption layer 32. The interface roughness is low, which reduces the contact resistance between the mixed absorption layer 33 and the second material absorption layer 32. The Hansen sphere radius R2 of the second material can be obtained based on the type of the second material.

[0107] For example, It can be 0.85, or 0.82, or 0.81, or 0.77, or 0.71, or 0.70, or 0.64, or 0.61.

[0108] Optionally, prior to step 102, the method may further include: determining HD21 based on the dispersive forces of the first material molecules, the dispersive forces of the second solvent molecules, the dipole forces of the first material molecules, the dipole forces of the second solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the second solvent molecules; and determining HD22 based on the dispersive forces of the second material molecules, the dispersive forces of the second solvent molecules, the dipole forces of the second material molecules, the dipole forces of the second solvent molecules, the hydrogen bonding forces of the second material molecules, and the hydrogen bonding forces of the second solvent molecules. The methods for determining HD21 and HD22 are similar to those for determining HD1, and will not be repeated here to avoid repetition.

[0109] It should be noted that if the number of types of the second material is greater than one, the combination of multiple types of the second material and the second solvent... Compared with the aforementioned various types of the first material and the first solvent The determination method is similar, and will not be repeated here to avoid repetition.

[0110] at the same time, According to Hansen's solubility theory, the second solvent has good solubility in both the first and second materials. In the mixed absorption layer 33, the first and second materials are mixed relatively uniformly, and the mixed absorption layer 33 has more interfaces between the first and second materials, which is conducive to exciton separation and the generation of free charges. Moreover, the second solvent has good solubility in both the first and second materials. In the mixed absorption layer 33, the clusters of the first and second materials are of similar size and both are small, which is conducive to the transport of excitons to the interface between the clusters of the first and second materials for dissociation and the generation of free charges.

[0111] HD3 is the Hansen distance between the third solvent and the second material, and R2 is the Hansen sphere radius of the second material. According to the Hansen solubility theory, the third solvent has a high solubility for the second material, resulting in a higher crystallinity and better uniformity of the second material absorption layer 32. This is beneficial for charge migration towards the electrode. Furthermore, the high solubility of the third solvent for the second material reduces aggregates and film splitting during the formation of the second material absorption layer, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell.

[0112] For example, It can be 0.85, or 0.82, or 0.80, or 0.78, or 0.73, or 0.70, or 0.62, or 0.49.

[0113] Optionally, prior to step 103, the method may further include: determining HD31 based on the dispersive forces of the first material molecules, the dispersive forces of the third solvent molecules, the dipole forces of the first material molecules, the dipole forces of the third solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the third solvent molecules; and determining HD3 based on the dispersive forces of the second material molecules, the dispersive forces of the third solvent molecules, the dipole forces of the second material molecules, the dipole forces of the third solvent molecules, the hydrogen bonding forces of the second material molecules, and the hydrogen bonding forces of the third solvent molecules. The determination of HD31 and HD3 is similar to the determination of HD1 described above, and will not be repeated here to avoid repetition.

[0114] It should be noted that if the number of types of the second material is greater than one, the combination of multiple types of the second material with the third solvent... Compared with the aforementioned various types of the first material and the first solvent The determination method is similar, and will not be repeated here to avoid repetition.

[0115] Optionally, the difference between the solubility of the second solvent in the first material and the solubility of the second solvent in the second material is less than a preset value. This means that the solubility of both the first and second materials in the second solvent is good and the difference is small. Consequently, the interaction forces between the first and second materials in the second solution are similar, and the first and second materials reach saturation almost simultaneously. Their crystallization processes are essentially the same, and the difference in their precipitation times is small or even almost identical. This results in very small differences in the size of the clusters, making it easy to prepare a uniform mixed phase. In the resulting mixed absorption layer 33, the first and second materials are mixed more uniformly, and the mixed absorption layer 33 has more interfaces between the first and second materials, which is beneficial for exciton separation and the generation of free charges. Furthermore, since the solubility of both the first and second materials in the second solvent is good and the difference is small, the size difference between the clusters of the first and second materials in the mixed absorption layer 33 is even smaller, and both are smaller in size. This is more conducive to exciton transport to the interface between the clusters of the first and second materials for dissociation and the generation of free charges. This preset value is set according to actual needs.

[0116] Optionally, the boiling point of the first solvent is less than or equal to 185°C. During the formation of the first material absorption layer 31, the first solvent has good volatility, is easy to dry, and the drying time of the first solvent is short. For example, the boiling point of the first solvent can be 185°C, 180°C, 178°C, 170°C, 166°C, or 160°C.

[0117] Optionally, the boiling point of the third solvent is less than or equal to 185°C. During the formation of the second material absorption layer 32, the third solvent has good volatility, is easy to dry, and the drying time of the third solvent is short, thus having little impact on the mixed absorption layer 33 and the first material absorption layer 31. For example, the boiling point of the third solvent can be 185°C, 181°C, 175°C, 170°C, 162°C, or 158°C.

[0118] The method for preparing an organic solar cell according to the present invention may include the following steps.

[0119] The first step is to prepare the solutions. Specifically, the first material is dissolved in a first solvent to obtain a first solution. The second material is dissolved in a third solvent to obtain a third solution. The first and second materials are then dissolved in a second solvent to obtain a second solution.

[0120] The second step is to clean the substrate. For example, after ultrasonically cleaning the ITO conductive glass for 20 minutes each in cleaning agent, water, acetone, and isopropanol, rinse it with ethanol, dry it with air, and treat it with ultraviolet ozone for 20 minutes to clean the substrate surface.

[0121] The third step is to deposit the first transport layer 2 on the substrate. The first transport layer 2 is spin-coated onto the cleaned ITO conductive glass. For the forward cell structure, the first transport layer 2 is a hole transport layer, and PEDOT:PSS can be selected; for the reverse cell structure, the first transport layer 2 is an electron transport layer, and ZnO, PEIE, etc. can be selected.

[0122] The fourth step is to prepare the organic absorber layer 3 on the first transport layer 2. The first solution is spin-coated onto the first transport layer 2, and after the film dries, the second solution is spin-coated, followed by drying, and then the third solution is spin-coated to prepare the organic absorber layer 3. Depending on the selected first and second materials, the drying process can include annealing, vacuum drying, etc.

[0123] Fifth step: Prepare the second transport layer 4 on the organic absorber layer 3. Spin-coat the second transport layer 4 onto the organic absorber layer 3. For a forward battery structure, the second transport layer 4 is an electron transport layer, which can be selected from materials such as PEIE, PDINO, and LiF. For a reverse battery structure, the second transport layer 4 is a hole transport layer, which can be selected from materials such as PEDOT:PSS, Ca, and MoO3.

[0124] The sixth step is to deposit the second electrode 5 on the second transport layer 4, remove the substrate, and deposit the first electrode 1 on the first transport layer 2. The materials of the first electrode 1 and the second electrode 5 are generally Ag, Al, etc.

[0125] It should be noted that the above-mentioned spin coating steps can also be achieved by scraping, slot coating, roll-to-roll coating, etc.

[0126] For example, in the aforementioned solution, the first material can be P3HT (a polymer of 3-hexylthiophene), and the first solvent can be AN (Anisole, CAS No. 100-66-3). The ratio of the Hansen distance between the first solvent AN and the first material P3HT to the Hansen sphere radius of the first material P3HT is 0.3. The first solvent AN has good solubility for the first material P3HT, and the boiling point of AN is 154°C. Alternatively, the first solvent can be PX (p-xylene, CAS No. 462-06-6). The ratio of the Hansen distance between the first solvent PX and the first material P3HT to the Hansen sphere radius of the first material P3HT is 0.75. The first solvent PX has good solubility for the first material P3HT, and the boiling point of PX is 138°C. Alternatively, the first solvent can be CF (Chloroform, CAS No. 67-66-3). The ratio of the Hansen distance between the first solvent CF and the first material P3HT to the Hansen sphere radius of the first material P3HT is 0.48. The first solvent CF dissolves the first material P3HT well, and the boiling point of CF is 61°C. During the formation of the first solution, the first material P3HT can be dissolved in the first solvent at a concentration of 8 mg / ml. The second material can be PCBM (fullerene derivative). The second solvent can be CF. The ratio of the Hansen distance between the second solvent CF and the first material P3HT to the Hansen sphere radius of the first material P3HT is 0.48. The second solvent CF dissolves the first material P3HT well. The ratio of the Hansen distance between the second solvent CF and the second material PCBM to the Hansen sphere radius of the second material PCBM is 0.65. The second solvent CF dissolves the second material PCBM well, and the boiling point of CF is 61°C. Alternatively, the second solvent can be EMS (Ethyl Methyl Sulfide, CAS No. 624-89-5). The ratio of the Hansen distance between the second solvent EMS and the first material P3HT to the Hansen sphere radius of the first material P3HT is 0.81, indicating good solubility of the first material P3HT in the second solvent EMS. The ratio of the Hansen distance between the second solvent EMS and the second material PCBM to the Hansen sphere radius of the second material PCBM is 0.78, indicating good solubility of the second material PCBM in the second solvent EMS. The boiling point of EMS is 67°C. During the formation of the second solution, the first material P3HT and the second material PCBM can be dissolved in the second solvent at a ratio of 1:1.5 and a total concentration of 17 mg / ml.The third solvent can be CFB (o-Chlorofluorobenzene, CAS No. 348-51-6). The ratio of the Hansen distance between the third solvent CFB and the second material PCBM to the Hansen sphere radius of the second material PCBM is 0.53. The third solvent CFB dissolves well in the second material PCBM. The boiling point of CFB is 137℃. The ratio of the Hansen distance between the third solvent CFB and the first material P3HT to the Hansen sphere radius of the first material P3HT is 1.13. The third solvent CFB does not dissolve in the first material P3HT. During the formation of the third solution, the second material PCBM can dissolve in the third solvent at a concentration of 15 mg / ml. The first solution can be spin-coated onto the substrate at 3000 rpm, and the third solution can be spin-coated onto the mixed absorber layer 33 at 2000 rpm for 60 seconds. In this organic solar cell, the second transport layer 4 can be molybdenum oxide.

[0127] It should be noted that the CAS (Chemical Abstracts Service) number mentioned throughout the text refers to the CAS number assigned by the Chemical Abstracts Service to each substance appearing in the literature. This is to avoid the trouble of chemical substances having multiple names and to make database retrieval more convenient.

[0128] like Figure 2 As shown, the present invention also provides an organic solar cell, which is prepared by any of the aforementioned methods for preparing organic solar cells. This organic solar cell has the same or similar beneficial effects as any of the aforementioned methods for preparing organic solar cells, and will not be described further here to avoid repetition.

[0129] Optionally, if the root mean square of the surface roughness of the mixed absorption layer 33 is less than or equal to 10 nm, the electron donor clusters and electron acceptor clusters in the mixed absorption layer 33 are more uniformly mixed, reducing phase separation. The two are nested together, and there are enough p / n interfaces in the mixed absorption layer 33 to reduce interfacial resistance. Moreover, the small surface roughness of the mixed absorption layer 33 is beneficial to the fabrication of subsequent layers.

[0130] For example, the root mean square of the surface roughness of the hybrid absorption layer 33 is 10 nm, or 7 nm, or 5 nm, or 4.6 nm, or 4.2 nm, or 4 nm, or 3.9 nm, or 3.7 nm, or 3.6 nm.

[0131] Optionally, the mixed absorption layer 33 includes electron donor clusters and electron acceptor clusters. The size of the electron donor clusters is less than or equal to 20 nm, and the size of the electron acceptor clusters is less than or equal to 20 nm. When the sizes of the two clusters are within the above range, there will not be too many grain boundaries in the mixed absorption layer 33, which reduces the energy loss in exciton transport. Furthermore, when the sizes of the two clusters are within the above range, there will be fewer defects in the mixed absorption layer 33, resulting in a longer free charge lifetime and less recombination.

[0132] For example, the hybrid absorption layer 33 includes an electron donor cluster and an electron acceptor cluster, wherein the size of the electron donor cluster is 20 nm, or 15 nm, or 10 nm, or 9 nm, or 8 nm, or 7 nm, or 4 nm, and the size of the electron acceptor cluster is 20 nm, or 19 nm, or 12 nm, or 10 nm, or 7 nm, or 5 nm, or 4 nm.

[0133] Optionally, in the hybrid absorption layer 33, the size of the electron donor clusters is 3 nm to 10 nm, and the size of the electron acceptor clusters is 3 nm to 10 nm. With the sizes of both clusters within this range, the hybrid absorption layer 33 has fewer grain boundaries, reducing energy loss during exciton transport. Furthermore, with the sizes of both clusters within this range, the hybrid absorption layer 33 has fewer defects, resulting in a longer free charge lifetime and less recombination.

[0134] For example, in the mixed absorber layer 33, the size of the electron donor cluster is 10 nm, or 8 nm, or 7 nm, or 6 nm, or 5 nm, or 4 nm, or 3 nm, and the size of the electron acceptor cluster is 10 nm, or 9 nm, or 8 nm, or 6 nm, or 5 nm, or 4 nm, or 3 nm.

[0135] Optionally, in the hybrid absorption layer 33, the size of the electron donor clusters is 5 nm to 10 nm, and the size of the electron acceptor clusters is 5 nm to 10 nm. With the sizes of both clusters within this range, the hybrid absorption layer 33 has fewer grain boundaries, reducing energy loss during exciton transport. Furthermore, with the sizes of both clusters within this range, the hybrid absorption layer 33 has fewer defects, resulting in a longer free charge lifetime and less recombination.

[0136] For example, in the mixed absorber layer 33, the size of the electron donor clusters is 10 nm, or 9 nm, or 7.6 nm, or 7.1 nm, or 6.9 nm, or 6 nm, or 5.5 nm, or 5 nm. The size of the electron acceptor clusters is 10 nm, or 9 nm, or 8.7 nm, or 8.2 nm, or 7.7 nm, or 6 nm, or 5 nm.

[0137] Optional, such as Figure 2As shown, the total thickness of the first material absorption layer 31, the mixed absorption layer 33, and the second material absorption layer 32 is greater than or equal to 100 nm, i.e., d1+d2+d3≥100 nm. Therefore, the total thickness of the first material absorption layer 31, the mixed absorption layer 33, and the second material absorption layer 32 is not too thin and can meet the photoelectric conversion requirements.

[0138] For example, d1+d2+d3 could be 100nm, 120nm, 130nm, 140nm, 150nm, 160nm, 180nm, 200nm, 230nm, 260nm, 300nm, 350nm, 370nm, or 400nm.

[0139] Optional, such as Figure 2 As shown, the thickness d3 of the first material absorption layer 31 is 40 nm to 170 nm, the thickness d2 of the mixed absorption layer 33 is 10 nm to 60 nm, and the thickness d1 of the second material absorption layer 32 is 40 nm to 170 nm. The thicknesses of the above layers are within the corresponding ranges, and the dimensions are relatively suitable, which is conducive to exciton transport.

[0140] This invention also provides a photovoltaic module comprising any of the aforementioned organic solar cells. The number of organic solar cells in the photovoltaic module is not specifically limited, and the photovoltaic module has the same or similar beneficial effects as any of the aforementioned organic solar cells; therefore, to avoid repetition, these effects will not be described again here. Furthermore, related aspects of the organic solar cell preparation method, the organic solar cell, and the photovoltaic module can be referred to mutually; to avoid repetition, related aspects are abbreviated.

[0141] The present application will be further explained below with reference to specific embodiments.

[0142] Example 1

[0143] The first step is to prepare the solutions. Specifically, the first material, PF2, is dissolved at a concentration of 4 mg / mL in the first solvent, CB (Chlorobenzene, CAS No. 108-90-7), and heated and stirred at 90°C for 24 hours to obtain the first solution. Then, PF2:IDTBR is dissolved at a concentration of 1:1, with a total concentration of 7 mg / mL, in the second solvent, FB (Fluorobenzene, CAS No. 462-06-6), and heated and stirred at 90°C for 24 hours to obtain the second solution. Finally, the second material, IDTBR, is dissolved at a concentration of 8 mg / mL in the third solvent, AN (Anisole, CAS No. 100-66-3), and heated and stirred at 90°C for 24 hours to obtain the third solution.

[0144] Table 1 shows the corresponding parameters of the solvent and solute in each solution prepared in Example 1. In Table 1 and all the appendices below, RED1 represents the ratio of the Hansen distance HD1 between the first solvent and the first material in the corresponding example or example to the Hansen sphere radius R1 of the first material. RED2 represents the ratio of the Hansen distance HD21 between the second solvent and the first material in the corresponding embodiment or example to the radius R1 of the Hansen sphere of the first material. RED3 represents the ratio of the Hansen distance HD22 between the second solvent and the second material in the corresponding embodiment or example to the radius R2 of the Hansen sphere of the second material. RED4 represents the ratio of the Hansen distance HD3 between the third solvent and the second material in the corresponding embodiment or example to the Hansen sphere radius R2 of the second material. RED5 represents the ratio of the Hansen distance HD31 between the third solvent and the first material in the corresponding embodiment or example to the radius R1 of the Hansen sphere of the first material.

[0145] Table 1: Corresponding parameters of solvent and solute in each solution prepared in Example 1

[0146]

[0147]

[0148] The second step involves ultrasonically cleaning the substrate ITO conductive glass for 30 minutes each in cleaning agent, water, acetone, and isopropanol, then rinsing it with ethanol, drying it with dry air, and treating it with ultraviolet ozone for 15 minutes to achieve the cleaning of the substrate surface.

[0149] The third step involves diluting PEDOT:PSS with deionized water at a volume ratio of 1:1, filtering it, and then spin-coating it onto cleaned ITO at 6000 rpm for 40 seconds. The resulting film is then annealed at 150°C for 15 minutes to obtain a film with a thickness of 20 nm to 50 nm, which is the first transport layer 2.

[0150] In the fourth step, the ITO / PEDOT:PSS substrate was transferred into a nitrogen glove box (water content less than 1 ppm, oxygen content less than 1 ppm). The first solution from the first step was spin-coated onto the ITO / PEDOT:PSS substrate at 1000 rpm for 150 seconds (acceleration: 400 rpm / s). After vacuum drying for 5 hours, a thin film with a thickness of 40 nm to 60 nm was obtained, which is the first material absorption layer 31. Next, the second solution was spin-coated onto the first material absorption layer 31. The spin-coating steps were as follows: first at 1500 rpm for 50 seconds (acceleration: 600 rpm / s), then at 3000 rpm for 120 seconds (acceleration: 2000 rpm / s), followed by a 10-minute rest period, and then vacuum drying for 5 hours to obtain a thin film with a thickness of 20 nm to 40 nm, which is the mixed absorption layer 33. The third solution was spin-coated onto the mixed absorption layer 33 at 1300 rpm for 120 seconds (acceleration: 200 rpm / s). After standing for 5 minutes, it was transferred into a vacuum drying oven and dried for 5 hours to obtain a thin film of 40 nm to 60 nm, which is the second material absorption layer 32.

[0151] Fifth step: A calcium metal layer of approximately 15 nm thickness is deposited on the second material absorption layer 32 under vacuum, at a deposition rate of... (angstroms / second)

[0152] Step 6: Evaporate a 150nm thick layer of Al onto the ITO / PEDOT:PSS / organic absorber layer 3 / calcium substrate. Evaporate rate: first 30nm. After 120nm, The substrate is removed, and the first electrode 1 is deposited on the first transport layer 2, ultimately obtaining the following: Figure 2 The organic solar cell shown.

[0153] It should be noted that the above-mentioned spin coating steps can also be achieved by scraping, slot coating, roll-to-roll coating, etc.

[0154] Example 2

[0155] Example 2 differs from Example 1 only in that the first solvent CB in Example 1 is replaced with PX (p-xylene, CAS number 462-06-6). The rest of Example 2 is the same as Example 1.

[0156] Table 2: Corresponding parameters of solvent and solute in each solution prepared in Example 2

[0157]

[0158] Example 3

[0159] Example 3 differs from Example 1 only in that the first solvent CB in Example 1 is replaced with VT (2-Vinyltoluene, 2-methylstyrene, CAS No. 611-15-4). The rest of Example 3 is the same as Example 1.

[0160] Table 3: Corresponding parameters of solvent and solute in each solution prepared in Example 3

[0161]

[0162] Comparative Example 1

[0163] The only difference between Comparative Example 1 and Example 1 is that the first solvent CB in Example 1 was replaced with TL (Toluene, CAS No. 108-88-3). The rest of Comparative Example 1 is the same as Example 1.

[0164] Table 4: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 1

[0165]

[0166]

[0167] Comparative Example 2

[0168] The only difference between Comparative Example 2 and Example 1 is that the first solvent CB in Example 1 was replaced with PC (p-cymene, p-methylisopropylbenzene, CAS No. 99-87-6). The rest of Comparative Example 2 is the same as Example 1.

[0169] Table 5: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 2

[0170]

[0171] Example 4

[0172] Example 4 differs from Example 1 only in that the third solvent AN in Example 1 is replaced with CF (Chloroform, CAS No. 67-66-3). The rest of Example 4 is the same as Example 1.

[0173] Table 6: Corresponding parameters of solvent and solute in each solution prepared in Example 4

[0174]

[0175] Comparative Example 3

[0176] The only difference between Comparative Example 3 and Example 1 is that the third solvent AN in Example 1 was replaced with PC (p-cymene, p-methylisopropylbenzene, CAS No. 99-87-6). The rest of Comparative Example 3 is the same as Example 1.

[0177] Table 7: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 3

[0178]

[0179] Example 5

[0180] Example 5 differs from Example 1 only in that the third solvent AN in Example 1 is replaced with BZ (Benzene, CAS No. 71-43-2). The rest of Example 5 is the same as Example 1.

[0181] Table 8: Corresponding parameters of solvent and solute in each solution prepared in Example 5

[0182]

[0183] Comparative Example 4

[0184] The only difference between Comparative Example 4 and Example 1 is that the third solvent AN in Example 1 was replaced with LM (Limonene, CAS No. 5989-27-5). The rest of Comparative Example 4 is the same as Example 1.

[0185] Table 9: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 4

[0186]

[0187]

[0188] Comparative Example 5

[0189] The only difference between Comparative Example 5 and Example 1 is that the second solvent FB in Example 1 was replaced with TE (Trichloroethylene, CAS No. 79-01-6). The rest of Comparative Example 5 is the same as Example 1.

[0190] Table 10: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 5

[0191]

[0192] Comparative Example 6

[0193] The only difference between Comparative Example 6 and Example 1 is that the second solvent FB in Example 1 was replaced with PX (p-xylene, CAS number 106-42-3). The rest of Comparative Example 6 is the same as Example 1.

[0194] Table 11: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 6

[0195]

[0196] Comparative Example 7

[0197] The only difference between Comparative Example 7 and Example 1 is that the second solvent FB in Example 1 was replaced with TL (Toluene, CAS No. 108-88-3). The rest of Comparative Example 7 is the same as Example 1.

[0198] Table 12: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 7

[0199]

[0200] Comparative Example 8

[0201] The only difference between Comparative Example 8 and Example 1 is that the second solvent FB in Example 1 was replaced with IB (Isopropylbenzene, CAS No. 98-82-8). The rest of Comparative Example 8 is the same as Example 1.

[0202] Table 13: Corresponding parameters of solvent and solute in each solution prepared in Comparative Example 8

[0203]

[0204] The electrical performance of the organic solar cells prepared in Examples 1 to 5 and Comparative Examples 1 to 8 was tested, and the results are shown in Table 14 below.

[0205] Table 14: Comparison of the electrical performance results of organic solar cells prepared in Examples 1 to 5 and Comparative Examples 1 to 8.

[0206]

[0207]

[0208] In Table 14, PCE refers to the photoelectric conversion efficiency of the organic solar cell. Compared with Comparative Examples 1 to 8, the organic solar cells prepared in Examples 1 to 5 all exhibit superior electrical performance. The main reason is that the first solvent has a high solubility for the first material, resulting in strong intermolecular forces between the first solvent and the first material. This promotes the growth of organic crystals rather than simple precipitation and aggregation. The resulting first material absorption layer 31 has high crystallinity, uniform morphology, low roughness, and a smoother or flatter surface. Free charges have higher mobility and lower energy loss in a uniform, highly crystalline film, which is beneficial for charge migration towards the electrode. Furthermore, the high solubility of the first solvent for the first material reduces aggregates and film splitting during the formation of the first material absorption layer 31, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. Simultaneously, the smoother surface of the first material absorption layer 31 also facilitates the preparation of subsequent layers. The third solvent has a high solubility for the second material, resulting in a second material absorber layer 32 with high crystallinity and uniform morphology. This facilitates charge migration towards the electrode. Furthermore, the high solubility of the third solvent reduces aggregates and film splitting during the formation of the second material absorber layer 32, allowing for smooth charge and exciton transport and improving the performance of the organic solar cell. The second solvent has good solubility for the first material, enabling the formation of a well-morphological contact interface between the mixed absorber layer 33 and the first material absorber layer 31. The low interface roughness reduces the contact resistance between the mixed absorber layer 33 and the first material absorber layer 31. The second solvent's good solubility for the second material also allows for the formation of a well-morphological contact interface between the mixed absorber layer 33 and the second material absorber layer 32. The low interface roughness further reduces the contact resistance between the mixed absorber layer 33 and the second material absorber layer 32. The second solvent exhibits good solubility in both the first and second materials, resulting in a relatively uniform mixture of the first and second materials in the formed mixed absorber layer 33. This mixed absorber layer 33 contains more interfaces between the first and second materials, facilitating exciton separation and the generation of free charges. Furthermore, the good solubility of the second solvent in both materials ensures that the clusters of the first and second materials in the mixed absorber layer 33 are of similar and relatively small size, which is beneficial for exciton transport to the interface between the clusters of the first and second materials for dissociation and the generation of free charges. Even if the third solvent wets the first material absorber layer 31 during the preparation of the second material absorber layer 32, the third solvent does not damage the structure and morphology of the first material absorber layer 31 because it is almost insoluble or has a solubility close to zero. This maintains the structural integrity of the first material absorber layer 31 and is beneficial for improving the performance of the organic solar cell.

[0209] Compared to Examples 1 to 3, the organic solar cells prepared in Comparative Examples 1 and 2 exhibited poorer electrical performance. This is mainly because the first solvent in Comparative Examples 1 and 2 had slightly lower solubility for the first material, resulting in relatively low crystallinity of the first absorber layer 31. This led to the formation of larger clusters with poor morphological uniformity, hindering the transport of free charges within the layer. Furthermore, the larger surface roughness of the film slightly affected the preparation of subsequent layers. Compared to Examples 4 and 5, the organic solar cells prepared in Comparative Example 3 also exhibited poorer electrical performance. This is mainly because the third solvent in Comparative Example 3 had slightly higher solubility for the first material. During the preparation of the second absorber layer 32, the third solvent seeped into the first absorber layer 31. Due to the higher solubility of the third solvent, it damaged the structure and morphology of the first absorber layer 31, negatively impacting the performance of the organic solar cell. Compared to Examples 4 and 5, the organic solar cells prepared in Comparative Example 4 exhibited poor electrical performance. This was primarily due to the fact that the third solvent in Comparative Example 4 had slightly lower solubility for the second material, resulting in relatively low crystallinity and poor morphological uniformity in the second absorber layer 32. Similarly, the organic solar cells prepared in Comparative Example 5 also showed poor electrical performance. This was mainly because the second solvent in Comparative Example 5 had slightly lower solubility for the first material, leading to a poor morphology at the contact interface between the mixed absorber layer 33 and the first material absorber layer 31. Furthermore, the cluster sizes of the first and second materials in the mixed absorber layer 33 differed significantly, which was detrimental to improving the performance of the organic solar cells. Finally, the organic solar cells prepared in Comparative Example 6 also exhibited poor electrical performance. This was primarily because the second solvent in Comparative Example 6 had a higher boiling point, requiring a longer drying time, which damaged the structure and morphology of the first material absorber layer 31, thus hindering the improvement of the organic solar cell's performance. The organic solar cells prepared in Comparative Examples 7 and 8 have poor electrical performance. The main reasons are as follows: In Comparative Examples 7 and 8, the boiling point of the second solvent is relatively high, and the drying time of the second solution is relatively long, which damages the structure and morphology of the first material absorption layer 31. In addition, the second solvent has poor solubility for the first material, resulting in poor morphology of the contact interface formed between the mixed absorption layer 33 and the first material absorption layer 31. Furthermore, the size difference between the clusters of the first material and the clusters of the second material in the mixed absorption layer 33 is relatively large, which is not conducive to improving the performance of the organic solar cell.

[0210] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of this application.

[0211] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes that element.

[0212] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0213] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing an organic solar cell, characterized in that, include: A substrate is provided, a first solution is disposed on the substrate, and dried to form a first material absorption layer; The first solution comprises a first material and a first solvent; A second solution is disposed on the first material absorption layer and dried to form a mixed absorption layer; the second solution includes a second material, a second solvent, and the first material; the first material is one of an electron donor material and an electron acceptor material, and the second material is another of an electron donor material and an electron acceptor material; A third solution is disposed on the mixed absorption layer and dried to form a second material absorption layer; the third solution comprises a third solvent and the second material. in, ≤0.85, HD1 is the Hansen distance between the first solvent and the first material, and R1 is the radius of the Hansen sphere of the first material; ≤0.85, HD21 is the Hansen distance between the second solvent and the first material; ≤0.85, HD22 is the Hansen distance between the second solvent and the second material, and R2 is the radius of the Hansen sphere of the second material; ≤0.85, HD3 is the Hansen distance between the third solvent and the second material; ≥1, HD31 is the Hansen distance between the third solvent and the first material.

2. The method for preparing an organic solar cell according to claim 1, characterized in that, The solubility of the second solvent in the first material, the solubility of the second solvent in the second material, the solubility of the first solvent in the first material, and the solubility of the third solvent in the second material are all greater than the solubility of the third solvent in the first material; and the boiling point of the first solvent and the boiling point of the third solvent are both greater than or equal to the boiling point of the second solvent.

3. The method for preparing an organic solar cell according to claim 2, characterized in that, The boiling point of the first solvent is less than or equal to 185°C; And / or, the boiling point of the third solvent is less than or equal to 185°C.

4. The method for preparing an organic solar cell according to claim 2, characterized in that, The difference between the solubility of the second solvent in the first material and the solubility of the second solvent in the second material is less than a preset value.

5. The method for preparing an organic solar cell according to claim 2, characterized in that, The boiling point of the second solvent is less than or equal to 100°C.

6. The method for preparing an organic solar cell according to any one of claims 1-5, characterized in that, The step of setting the first solution on the substrate and drying it includes: A first solution is disposed on the substrate and dried in a first atmosphere; in the first atmosphere, the volume content of the gaseous first solvent is less than or equal to 30% of the total volume of the first atmosphere. And / or, the step of applying a second solution to the first material absorbent layer and drying it includes: A second solution is disposed on the first material absorption layer and dried in a second atmosphere; in the second atmosphere, the volume content of the gaseous second solvent is less than or equal to 30% of the total volume of the second atmosphere. And / or, the provision of a third solution on the mixed absorbent layer and drying includes: A third solution is disposed on the mixed absorption layer and dried in a third atmosphere; in the third atmosphere, the volume content of the gaseous third solvent is less than or equal to 30% of the total volume of the third atmosphere.

7. The method for preparing an organic solar cell according to any one of claims 1-5, characterized in that, The drying process includes at least one of vacuum drying and heat drying. During the drying process, the ambient temperature is between 20°C and 170°C.

8. The method for preparing an organic solar cell according to claim 1 or 2, characterized in that, Before the first solution is applied to the substrate and dried, the method further includes: HD1 is determined based on the dispersive forces of the first material molecules, the dispersive forces of the first solvent molecules, the dipole forces of the first material molecules, the dipole forces of the first solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the first solvent molecules. Before applying the second solution to the first material absorbent layer and drying it, the method further includes: HD21 is determined based on the dispersive forces of the first material molecules, the dispersive forces of the second solvent molecules, the dipole forces of the first material molecules, the dipole forces of the second solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the second solvent molecules. HD22 is determined based on the dispersive forces of the second material molecules, the dispersive forces of the second solvent molecules, the dipole forces of the second material molecules, the dipole forces of the second solvent molecules, the hydrogen bonding forces of the second material molecules, and the hydrogen bonding forces of the second solvent molecules. Before the third solution is applied to the mixed absorption layer and dried, the method further includes: HD31 is determined based on the dispersive forces of the first material molecules, the dispersive forces of the third solvent molecules, the dipole forces of the first material molecules, the dipole forces of the third solvent molecules, the hydrogen bonding forces of the first material molecules, and the hydrogen bonding forces of the third solvent molecules. HD3 is determined based on the dispersive forces of the second material molecules, the dispersive forces of the third solvent molecules, the dipole forces of the second material molecules, the dipole forces of the third solvent molecules, the hydrogen bonding forces of the second material molecules, and the hydrogen bonding forces of the third solvent molecules.

9. The method for preparing an organic solar cell according to any one of claims 1-5, characterized in that, The step of setting the first solution on the substrate includes setting the first solution on the substrate by at least one of spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing. And / or, the provision of the second solution on the first material absorption layer includes: using at least one of spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing to provide the second solution on the first material absorption layer; And / or, the provision of the third solution on the mixed absorption layer includes: using at least one of spin coating, blade coating, slot coating, roll-to-roll coating, and inkjet printing to provide the third solution on the mixed absorption layer.

10. The method for preparing an organic solar cell according to any one of claims 1-5, characterized in that, The step of setting the first solution on the substrate and drying it includes: A first electrode is disposed on the substrate; A first transport layer is disposed on the first electrode; A first solution is applied to the first transport layer and then dried. After forming the second material absorption layer, the method further includes: A second transport layer is disposed on the second material absorption layer; A second electrode is formed on the second transport layer.

11. The method for preparing an organic solar cell according to claim 10, characterized in that, The provision of the first transport layer on the first electrode includes: using at least one of spin coating, blade coating, slot coating, roll-to-roll coating, inkjet printing, and vacuum evaporation to provide the first transport layer on the first electrode. The provision of a second transport layer on the second material absorption layer includes: A second transport layer is formed on the second material absorption layer by employing at least one of spin coating, blade coating, slot coating, roll-to-roll coating, inkjet printing, and vacuum evaporation.

12. An organic solar cell, characterized in that, include: A first material absorption layer, a second material absorption layer located above the first material absorption layer, and a mixed absorption layer located between the first material absorption layer and the second material absorption layer; The first material absorption layer is formed by evaporating a first solvent from a first solution containing the first material; the second material absorption layer is formed by evaporating a third solvent from a third solution containing the second material; the mixed absorption layer is formed by evaporating a second solvent from a second solution containing the first material and the second material; the first material is one of an electron donor material and an electron acceptor material, and the second material is another of an electron donor material and an electron acceptor material. in, ≤0.85, HD1 is the Hansen distance between the first solvent and the first material, and R1 is the radius of the Hansen sphere of the first material; ≤0.85, HD21 is the Hansen distance between the second solvent and the first material; ≤0.85, HD22 is the Hansen distance between the second solvent and the second material, and R2 is the radius of the Hansen sphere of the second material; ≤0.85, HD3 is the Hansen distance between the third solvent and the second material; ≥1, HD31 is the Hansen distance between the third solvent and the first material.

13. The organic solar cell according to claim 12, characterized in that, The root mean square of the surface roughness of the hybrid absorption layer is less than or equal to 10 nm. And / or, the boiling point of the third solvent is less than or equal to 185°C.

14. The organic solar cell according to claim 12 or 13, characterized in that, The hybrid absorption layer comprises electron donor clusters and electron acceptor clusters, wherein the size of the electron donor clusters is less than or equal to 20 nm, and the size of the electron acceptor clusters is less than or equal to 20 nm.

15. The organic solar cell according to claim 14, characterized in that, The electron donor cluster has a size of 3 nm to 10 nm; the electron acceptor cluster has a size of 3 nm to 10 nm.

16. The organic solar cell according to claim 14, characterized in that, The electron donor cluster has a size of 5 nm to 10 nm; the electron acceptor cluster has a size of 5 nm to 10 nm.

17. The organic solar cell according to claim 12 or 13, characterized in that, The total thickness of the first material absorption layer, the mixed absorption layer, and the second material absorption layer is greater than or equal to 100 nm; the direction of the thickness is parallel to the setting direction of the first material absorption layer and the mixed absorption layer.

18. The organic solar cell according to claim 12 or 13, characterized in that, The thickness of the first material absorption layer is 40 nm to 170 nm; The thickness of the hybrid absorption layer is 10 nm to 60 nm; The thickness of the second material absorption layer is 40 nm to 170 nm; the direction of the thickness is parallel to the direction in which the first material absorption layer and the mixed absorption layer are disposed.

19. The organic solar cell according to claim 18, characterized in that, The organic solar cell further includes a first electrode located on the side of the first material absorber layer away from the hybrid absorber layer, and a first transport layer located between the first electrode and the first material absorber layer, the thickness of the first transport layer being 5 nm to 50 nm. The organic solar cell further includes a second transport layer located on the side of the second material absorber layer away from the first electrode, and the thickness of the second transport layer is 5 nm to 50 nm.

20. A photovoltaic module, characterized in that, include: The organic solar cell according to any one of claims 12 to 19.

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