Perovskite solar cell and preparation method thereof, photovoltaic module

Abstract

The application discloses a perovskite solar cell, a preparation method thereof and a photovoltaic module. The perovskite solar cell comprises a perovskite layer and a passivation layer arranged on the surface of the perovskite layer. The raw material for preparing the passivation layer comprises a material containing a homocysteic acid thiolactone structure. The application can better improve the defect coverage effect on the perovskite surface and the grain boundary, thereby further enhancing the passivation quality of the perovskite layer.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and more particularly to a perovskite solar cell and its preparation method, as well as a photovoltaic module. Background Technology

[0002] Perovskite solar cells, with their advantages of high efficiency and low manufacturing cost, have become one of the most popular types of solar cells. However, numerous defects still exist on the surface and at the grain boundaries of the perovskite layer in perovskite solar cells. Current passivating agents are not very effective at covering these defects, leading to increased nonradiative recombination and relatively high open-circuit voltage loss, which severely limits further improvements in the photoelectric conversion efficiency of perovskite solar cells. Summary of the Invention

[0003] To improve the coverage of defects on the surface and grain boundaries of perovskites, this application provides a perovskite solar cell, its preparation method, and a photovoltaic module.

[0004] In a first aspect, embodiments of this application provide a perovskite solar cell.

[0005] A perovskite solar cell includes a perovskite layer and a passivation layer stacked on the surface of the perovskite layer. The raw material for preparing the passivation layer includes a material containing a homocysteine ​​thiolactone structure.

[0006] As an optional implementation, in the embodiments of this application, the material containing the homocysteine ​​thiolactone structure contains a carbonyl group, a protonated amino group, and a thiol group, wherein the carbonyl group reacts with the Pb in the perovskite layer. 2+ A Pb-O coordination bond is formed, the protonated amino group is bonded to the halogen vacancy in the perovskite layer via hydrogen bonding, and the thiol group is bonded to the Pb in the perovskite layer. 2+ Combine.

[0007] As an optional implementation, in the embodiments of this application, the passivation layer further includes one or both of n-octylammonium iodide and ethylenediamine dihydroiodide.

[0008] As an optional implementation, in the embodiments of this application, the material containing the homocysteine ​​thiolactone structure includes one or more combinations of DL-homocysteine ​​thiolactone hydrochloride, DL-homocysteine ​​thiolactone, D-homocysteine ​​thiolactone hydrochloride, and L-homocysteine ​​thiolactone hydrochloride. And / or, In the passivation layer, the mass percentage of the material containing the homocysteine ​​thiolactone structure is not less than 5%.

[0009] As an optional implementation, in the embodiments of this application, the passivation layer further includes one or both of n-octylammonium iodide and ethylenediamine dihydroiodide.

[0010] As an optional implementation, in the embodiments of this application, the passivation layer further includes the n-octylammonium iodide and the ethylenediamine dihydroiodide, wherein the mass ratio of the material containing the homocysteine ​​thiolactone structure, the mass of the n-octylammonium iodide and the mass of the ethylenediamine dihydroiodide is (0.1~5):(1.5~2):(1.5~2).

[0011] As an optional implementation, in the embodiments of this application, the thickness of the passivation layer is 0.5 nm to 50 nm.

[0012] As an optional implementation, in the embodiments of this application, the perovskite solar cell includes a perovskite single-junction solar cell or a perovskite tandem solar cell. The perovskite single-junction solar cell includes the following structure: A transparent conductive substrate and a first transport layer stacked on the transparent conductive substrate; The perovskite layer and the passivation layer are stacked sequentially on the side of the first transport layer away from the transparent conductive substrate; A second transport layer is stacked on the side of the passivation layer away from the transparent conductive substrate. One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer. A first electrode is disposed on the second transport layer, and a second electrode is disposed on the transparent conductive substrate; The perovskite tandem solar cell includes the following structure: A bottom battery and a carrier intermediate composite layer and a first transport layer sequentially stacked on the bottom battery; The perovskite layer and the passivation layer are stacked sequentially on the side of the first transport layer away from the bottom cell. The passivation layer is further stacked on the side away from the bottom battery, and one of the first transport layer and the second transport layer is an electron transport layer and the other is a hole transport layer. The second transmission layer has a transparent conductive layer stacked on the side opposite to the bottom battery; The transparent conductive layer is stacked on the side opposite to the bottom battery and has a first electrode.

[0013] Secondly, embodiments of this application provide a method for preparing a perovskite solar cell.

[0014] A method for fabricating a perovskite solar cell includes the following steps: A passivation solution is applied to the surface of a perovskite layer, followed by annealing to form a passivation layer on the surface of the perovskite layer. The passivation solution comprises a material containing a homocysteine ​​thiolactone structure.

[0015] As an optional implementation, in the embodiments of this application, the concentration of the material containing the homocysteine ​​thiolactone structure in the passivation solution is 0.1 mg / mL to 5 mg / mL; And / or, The passivation solution further includes n-octylammonium iodide and / or ethylenediamine dihydroiodide, wherein the concentration of n-octylammonium iodide is 1.5 mg / mL to 2 mg / mL, and the concentration of ethylenediamine dihydroiodide is 1.5 mg / mL to 2 mg / mL; And / or, In the step of preparing the passivation layer, the annealing temperature is 80℃~90℃ and the annealing time is 2 min~5 min; And / or, The passivation solution can be in the form of anhydrous ethanol or isopropanol.

[0016] Thirdly, embodiments of this application provide a photovoltaic module.

[0017] A photovoltaic module includes a perovskite solar cell as mentioned in the first aspect or a perovskite solar cell prepared by the preparation method mentioned in the second aspect.

[0018] Compared with the prior art, the beneficial effects of this application are as follows: This application introduces a material containing a homocysteine ​​thiolactone structure, which significantly improves the defect passivation quality of the perovskite layer, thereby effectively enhancing the photoelectric conversion efficiency of perovskite solar cells. Specifically, the homocysteine ​​thiolactone has a cyclic structure. The inherent conformational constraints of this cyclic structure maintain the molecular framework in a rigid pre-organized state. When it comes into contact with the perovskite layer and undergoes a ring-unraveling reaction, the released energy drives the carbonyl, amino, and thiol groups in the molecule to efficiently bind to surface defect sites in a specific spatial configuration. This results in a more regular and dense arrangement and bonding of the material on the surface and at grain boundaries of the perovskite layer, effectively improving the uniformity and coverage of defects, and ultimately improving the quality of the perovskite layer. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the first perovskite solar cell disclosed in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the second type of perovskite solar cell disclosed in the embodiments of this application; Figure 3 This is a schematic diagram illustrating the fabrication process of a passivation layer on a perovskite layer, as disclosed in the embodiments of this application. Figure 4 This is a comparison chart of the X-ray diffraction (XRD) test results of Example 1 and Comparative Example 1 of this application; Figure 5 This is a scanning electron microscope (SEM) test result image of Embodiment 1 of this application; Figure 6 This is a scanning electron microscope (SEM) test result of Comparative Example 1 of this application.

[0021] Icons: 1. Perovskite layer; 2. Passivation layer; 3A. Transparent conductive substrate; 3B. Bottom cell; 4. First transport layer; 41. Hole transport layer; 5. Second transport layer; 51. Electron transport layer; 6. First electrode; 7. Second electrode; 8. Carrier intermediate recombination layer; 9. Transparent conductive layer. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Introducing a passivation layer onto the surface of a perovskite layer can effectively passivate surface and grain boundary defects. Currently, materials commonly used for passivating perovskite surface and grain boundary defects include alkylammonium salts (such as phenylethylammonium iodide, PEAI) and Lewis base molecules (such as compounds containing carbonyl or amino groups). However, these passivating agents have relatively limited functionality, primarily targeting either cationic or anionic defects, making it difficult to achieve synergistic and comprehensive passivation of multiple defects. Furthermore, the molecular structures of currently used passivating agents are typically flexible linear structures, allowing the chemical bonds within the passivating agent molecules to rotate freely. These passivating materials exhibit low coverage of surface defects in perovskite layers, limiting further improvements in the passivation quality of the perovskite surface.

[0024] To better passivate defects on the surface or at grain boundaries of the perovskite layer, this application provides a perovskite solar cell, its fabrication method, and a photovoltaic module. The technical solution of this application will be further described below with reference to embodiments and accompanying drawings.

[0025] In a first aspect, embodiments of this application provide a perovskite solar cell.

[0026] Reference Figure 1 or Figure 2 The perovskite solar cell includes a perovskite layer 1 and a passivation layer 2 stacked on the surface of the perovskite layer 1. The raw materials for preparing the passivation layer 2 include materials containing a homocysteine ​​thiolactone structure.

[0027] The material containing a homocysteine ​​thiolactone structure used in this application can form a regular and dense arrangement and bonding on the surface of the perovskite layer 1, thereby better filling various defects on the surface and at the grain boundaries of the perovskite layer 1 and improving the passivation quality of the perovskite layer 1. Specifically, unlike conventionally used flexible linear passivating agent molecules, the homocysteine ​​thiolactone structure is a cyclic structure. This cyclic structure has conformational constraints, and the atoms in the molecule cannot rotate freely. This locks the entire framework of the material containing the homocysteine ​​thiolactone structure into a relatively rigid and pre-organized geometry. When a material containing a homocysteine ​​thiolactone structure comes into contact with the surface of perovskite layer 1, it spontaneously undergoes a relatively vigorous ring-breaking reaction. During the ring-breaking process, energy is released, driving the carbonyl groups, protonated amino groups, and thiol groups in the homocysteine ​​thiolactone-containing material to bind to the defect sites on the surface of perovskite layer 1 with high reactivity and specific spatial configuration. This allows the material containing the homocysteine ​​thiolactone structure to arrange and bond on the surface of perovskite layer 1 in a more regular and dense manner, thereby improving the defect coverage and uniformity on the surface and grain boundaries of perovskite layer 1, effectively improving the quality of perovskite layer 1, and achieving an increase in the efficiency of perovskite solar cells.

[0028] In some embodiments, the material containing the homocysteine ​​thiolactone structure contains a carbonyl group, a protonated amino group, and a thiol group, with the carbonyl group reacting with Pb in the perovskite layer 1. 2+ Pb-O coordination bonds are formed, and the protonated amino groups are bonded to the halogen vacancies in perovskite layer 1 via hydrogen bonds. The thiol groups are bonded to the Pb in perovskite layer 1. 2+ Combine.

[0029] Carbonyl groups, protonated amino groups, and mercapto groups can respectively enhance the surface quality of perovskite layer 1 by recombinating with defects on the surface. Among these, the carbonyl group, as a strong Lewis base, can recombine with uncoordinated Pb on the surface of perovskite layer 1. 2+ Strong coordination bonds are formed, thereby passivating Pb. 2+ Defects. Protonated amino groups bind to negatively charged halogen vacancies (such as I) on the perovskite surface via hydrogen bonds. - The thiol groups bind to vacancies or through electrostatic interactions, neutralizing local charges and inhibiting ion migration; thiol groups bind to Pb on the perovskite surface. 2+Weak coordination or physical adsorption is formed, further enhancing interfacial bonding and suppressing the generation of deep defects in perovskite layer 1. Through the synergistic effect of the above three functional groups, materials containing homocysteine ​​thiolactone structures can simultaneously passivate both cation and anion defects on the surface of perovskite layer 1, achieving comprehensive and synergistic passivation of multiple defects, significantly improving the surface passivation quality of perovskite layer 1, and further improving the open-circuit voltage and photoelectric conversion efficiency of perovskite solar cells.

[0030] In some embodiments, the materials containing a homocysteine ​​thiolactone structure include one or more combinations of DL-homocysteine ​​thiolactone hydrochloride, DL-homocysteine ​​thiolactone, D-homocysteine ​​thiolactone hydrochloride, and L-homocysteine ​​thiolactone hydrochloride. Materials containing a homocysteine ​​thiolactone structure, such as DL-homocysteine ​​thiolactone, D-homocysteine ​​thiolactone hydrochloride, and L-homocysteine ​​thiolactone hydrochloride, can utilize this structure to effectively passivate surface defects in the perovskite layer 1, achieving better coverage of these defects.

[0031] In some embodiments, the mass percentage of the material containing the homocysteine ​​thiolactone structure in the passivation layer 2 is not less than 5%. When the content of the material containing the homocysteine ​​thiolactone structure is not less than 5%, the energy released by the ring-unwinding reaction of the material containing the homocysteine ​​thiolactone structure is higher, which can better activate carbonyl groups, protonated amino groups, and thiol groups, enabling these groups to bind to the defect sites on the surface of the perovskite layer 1 with higher reactivity, thereby ensuring effective passivation of the defects on the surface of the perovskite layer 1. Exemplarily, the mass percentage of the material containing the homocysteine ​​thiolactone structure in the passivation layer 2 can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc.

[0032] In some embodiments, the passivation layer is composed of a material containing a homocysteine ​​thiolactone structure. In other embodiments, the passivation layer 2 further includes one or both of n-octylammonium iodide and ethylenediamine dihydroiodide. The material containing the homocysteine ​​thiolactone structure complements the passivation function of n-octylammonium iodide and ethylenediamine dihydroiodide. As shown above, the material containing the homocysteine ​​thiolactone structure addresses deep defects (Pb). 2+For dangling bonds and shallow defects (halogen vacancies), ethylenediamine dihydroiodide can provide additional iodide ions to further fill surface defects. Octylammonium iodide has good hydrophobicity and can form a hydrophobic defect protection layer on the outermost layer of the passivation layer, thereby improving the passivation layer 2's resistance to water and oxygen intrusion. Therefore, combining materials containing homocysteine ​​thiolactone structures with octylammonium iodide and ethylenediamine dihydroiodide can form a deep-medium-shallow layered passivation structure, achieving more comprehensive and efficient passivation of surface defects in the perovskite layer 1.

[0033] In some embodiments, the passivation layer 2 further includes n-octylammonium iodide and ethylenediamine dihydroiodide, with the mass ratio of the material containing the homocysteine ​​thiolactone structure, the mass of n-octylammonium iodide, and the mass of ethylenediamine dihydroiodide being (0.1~5):(1.5~2):(1.5~2). When the material containing the homocysteine ​​thiolactone structure, n-octylammonium iodide, and ethylenediamine dihydroiodide are blended in a specific mass ratio, it is beneficial for each component to provide better complementary passivation, thereby further improving the passivation effect on the perovskite layer 1 surface. For example, the mass ratio of the material containing the homocysteine ​​thiolactone structure, the mass of n-octylammonium iodide, and the mass of ethylenediamine dihydroiodide can be 1:1.5:1.5, 2:1.5:1.5, 3:2:2, 4:1.5:1.5, etc.

[0034] In some embodiments, the thickness of the passivation layer 2 is 0.5 nm to 50 nm. Controlling the thickness of the passivation layer 2 within this range better ensures its coverage of the perovskite layer 1 surface while maintaining good carrier transport performance. When the thickness of the passivation layer 2 is less than 0.5 nm, its coverage of defect sites on the perovskite layer 1 surface is poor, leading to a decrease in passivation efficiency. When the thickness of the passivation layer 2 is greater than 50 nm, it hinders the transport of photogenerated carriers, which is detrimental to further improving the photoelectric conversion efficiency of the perovskite solar cell. For example, the thickness of the passivation layer 2 can be 0.5 nm, 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0035] In some embodiments, the perovskite solar cell includes, for example, Figure 1 The perovskite single-junction solar cell shown is or is like Figure 2 The perovskite tandem solar cell shown is an example of the perovskite layer 1 and passivation layer 2 stacked configuration described in this application. This configuration is suitable for both single-junction perovskite solar cells and multilayer perovskite solar cells.

[0036] For example Figure 1The perovskite single-junction solar cell shown has a passivation layer 2 disposed between the perovskite layer 1 and the second transport layer 5. This passivation layer effectively passivates defects on the surface of the perovskite layer 1, improving the open-circuit voltage and fill factor of the perovskite single-junction solar cell. For example... Figure 2 The perovskite tandem solar cell shown has a passivation layer 2 disposed between the perovskite layer 1 and the second transport layer 5. This can significantly improve the performance of the perovskite top cell without affecting the performance of the bottom cell 3B, thereby improving the overall photoelectric conversion efficiency of the perovskite tandem solar cell.

[0037] Furthermore, such as Figure 1 The perovskite single-junction solar cell shown includes the following structure: A transparent conductive substrate 3A and a first transport layer 4 stacked on the transparent conductive substrate 3A; The perovskite layer 1 and the passivation layer 2 are stacked sequentially on the side of the first transport layer 4 away from the transparent conductive substrate 3A; A second transport layer 5 is stacked on the side of the passivation layer 2 away from the transparent conductive substrate 3A. One of the first transport layer 4 and the second transport layer 5 is an electron transport layer 51, and the other is a hole transport layer 41. A first electrode 6 is disposed on the second transport layer 5, and a second electrode 7 is disposed on the transparent conductive substrate 3A; like Figure 2 The perovskite tandem solar cell shown includes the following structure: The bottom cell 3B and the intermediate composite layer 8 and the first transport layer 4 are stacked sequentially on the bottom cell 3B; The perovskite layer 1 and the passivation layer 2 are stacked sequentially on the side of the first transport layer 4 away from the bottom cell 3B; On the side of the passivation layer 2 away from the bottom battery 3B, a second transport layer 5 is also stacked. One of the first transport layer 4 and the second transport layer 5 is an electron transport layer 51, and the other is a hole transport layer 41. A transparent conductive layer 9 is stacked on the side of the second transmission layer 5 away from the bottom battery 3B. A first electrode 6 is stacked on the side of the transparent conductive layer 9 away from the bottom battery 3B.

[0038] Furthermore, in the perovskite tandem solar cell, the materials of the intermediate carrier composite layer 8 and the transparent conductive layer 9 can both be transparent conductive oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium cerium oxide (ICO). The transparent conductive oxides can be prepared by magnetron sputtering or atomic vapor deposition (ALD). The thickness of the intermediate carrier composite layer 8 is 20 nm to 30 nm. For example, the thickness of the intermediate carrier composite layer 8 can be 20 nm, 25 nm, or 30 nm. The thickness of the transparent conductive layer 9 is 80 nm to 120 nm. For example, the thickness of the transparent conductive layer 9 can be 80 nm, 90 nm, 100 nm, 110 nm, or 120 nm. The bottom cell 3B also includes a second electrode 7 disposed opposite to the first electrode 6. The materials of the first electrode 6 and the second electrode 7 are both metallic materials with good conductivity, such as silver or copper. The preparation method of the first electrode 6 and the second electrode 7 can be physical vapor deposition (PVD). The bottom cell 3B includes a heterojunction bottom cell and a passivated contact bottom cell. When the bottom cell 3B is a heterojunction bottom cell, the surface of the heterojunction bottom cell 3B has a textured structure, and the height of the textured structure can be 1.5 μm, 2 μm, etc.

[0039] In the above-mentioned perovskite single-junction solar cells or perovskite tandem solar cells, the hole transport layer 41 is mainly responsible for hole collection and transport in the perovskite solar cell structure, with a thickness of 20 nm to 30 nm. For example, the thickness of the hole transport layer 41 can be 20 nm, 25 nm, or 30 nm, and the material of the hole transport layer 41 can be nickel oxide (NiO). X The main preparation methods for nickel oxide are solution spin coating and magnetron sputtering. The material of hole transport layer 41 can also be a self-assembled monomolecular material, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] or other materials with high hole mobility. The self-assembled monomolecular material can be [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), 4-(3,6-dimethyl-9H-carbazole-9-yl)butylphosphonic acid (Me-4PACz), etc.

[0040] Electron transport layer 51 in the perovskite solar cell structure is mainly responsible for electron collection and transport, and can be a fullerene (C) layer. 60 Fullerenes and their derivatives can be prepared by physical vapor deposition (PVD). The material of electron transport layer 51 can also be metal oxides such as tin oxide. The preparation method of metal oxides such as tin oxide can be atomic vapor deposition (ALD).

[0041] Secondly, embodiments of this application provide a method for preparing a perovskite solar cell.

[0042] A method for fabricating a perovskite solar cell includes the following steps: Provide such as Figure 3 As shown in Figure (a), a passivation solution is applied to the surface of the perovskite layer 1, followed by annealing to form a passivation layer 2 on the surface of the perovskite layer 1, resulting in the following: Figure 3 The structure shown in Figure (b) is where the passivation solution comprises a material containing a homocysteine ​​thiolactone structure.

[0043] The surface of perovskite layer 1 readily adsorbs trace amounts of moisture from the environment. When a material containing a homocysteine ​​thiolactone structure comes into contact with the surface of perovskite layer 1, the nucleophilic moisture and defect sites on the surface of perovskite layer 1 trigger a ring-opening reaction in the homocysteine ​​thiolactone-containing material. This causes the homocysteine ​​thiolactone-containing material to bind to the defect sites on the surface of perovskite layer 1 with a specific spatial configuration. Furthermore, the energy released by the ring-opening reaction can enhance the reactivity of the carbonyl groups, protonated amino groups, and thiol groups in the homocysteine ​​thiolactone-containing material, thereby improving the binding effect of each group to the defect sites on the surface of perovskite layer 1. This allows the homocysteine ​​thiolactone-containing material to arrange and bond in a more regular and dense manner on the surface of perovskite layer 1, thus improving the defect coverage and uniformity on the surface and grain boundaries of perovskite layer 1, effectively improving the quality of perovskite layer 1, and achieving an increase in the efficiency of perovskite solar cells.

[0044] The preparation method described in this application has the advantages of simple process and convenient operation, and is suitable for large-scale industrial production.

[0045] In some embodiments, the concentration of the material containing the homocysteine ​​thiolactone structure in the passivation solution is from 0.1 mg / mL to 5 mg / mL. This concentration of the homocysteine ​​thiolactone-containing material enables better alignment and coverage on the surface of the perovskite layer 1, better passivating surface defects in the perovskite layer 1, thereby further improving the photoelectric conversion efficiency of the perovskite solar cell. Exemplarily, the concentration of the material containing the homocysteine ​​thiolactone structure can be 0.1 mg / mL, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, etc.

[0046] In some embodiments, the passivation solution further includes n-octylammonium iodide and / or ethylenediamine dihydroiodide, wherein the concentration of n-octylammonium iodide is 1.5 mg / mL to 2 mg / mL, and the concentration of ethylenediamine dihydroiodide is 1.5 mg / mL to 2 mg / mL. Mixing n-octylammonium iodide, ethylenediamine dihydroiodide, and materials containing homocysteine ​​thiolactone structures at specific concentrations allows for a better synergistic passivation effect, thereby further enhancing the surface passivation effect of the perovskite layer 1. Exemplarily, the concentration of n-octylammonium iodide can be 1.5 mg / mL, 1.7 mg / mL, 2 mg / mL, etc., and the concentration of ethylenediamine dihydroiodide can be 1.5 mg / mL, 1.7 mg / mL, 2 mg / mL, etc.

[0047] In some embodiments, during the preparation of the passivation layer 2, the annealing temperature is 80°C to 90°C, and the annealing time is 2 min to 5 min. By controlling the temperature and time of this annealing process, the solvent in the passivation solution can be effectively evaporated, ensuring the formation quality of the passivation layer 2. Furthermore, the relatively low annealing temperature reduces thermal damage to the perovskite layer 1. Exemplarily, the annealing temperature can be 80°C, 85°C, or 90°C, and the annealing time can be 2 min, 3 min, or 5 min, etc.

[0048] In some embodiments, the passivation solution solvent includes anhydrous ethanol or isopropanol. Anhydrous ethanol or isopropanol has good solubility for materials containing homocysteine ​​thiolactone structures, n-octylammonium iodide, and / or ethylenediamine dihydroiodide, which is beneficial for forming a passivation solution with good dissolution uniformity. At the same time, these two solvents have low boiling points and good volatility, which facilitates rapid evaporation during annealing to form a dense passivation layer 2.

[0049] Furthermore, the perovskite layer 1 of this application can be prepared using a one-step or two-step method. Specifically, the one-step method for preparing the perovskite layer 1 involves dissolving a perovskite precursor salt (such as a mixture of lead iodide and an organic halide) in an organic solvent to form a perovskite precursor solution, coating and annealing the perovskite precursor solution to obtain the perovskite layer 1. The two-step method for preparing the perovskite layer 1 involves first depositing an inorganic framework layer (such as a lead iodide framework layer), and then coating an organic cation solution onto the surface of the inorganic framework layer. The organic cation solution is a mixed solution containing organic cations such as formamidine iodoformin (FAI), formamidine bromoformin (FABr), and methylchloroamine (MACl). After annealing, the organic cations diffuse into the inorganic framework layer, thereby forming the perovskite light-absorbing layer 11. The coating method can be spin coating, blade coating, or slot coating. For the perovskite layer 1 prepared by the above two processes, the passivation solution of this application can effectively act on the surface of the perovskite layer 1, improving the coverage effect on the surface defects of the perovskite layer 1.

[0050] In some embodiments, the material of the perovskite layer can be Cs. y (FA 1-x MA x ) 1-y Pb(I 1-z-w Br z Cl w )3, where x is 0.10 to 0.20, y is 0.05 to 0.20, z is 0.10 to 0.25, and w is less than or equal to 0.10.

[0051] Thirdly, embodiments of this application provide a photovoltaic module.

[0052] A photovoltaic module includes a perovskite solar cell as mentioned in the first aspect or a perovskite solar cell prepared by the preparation method mentioned in the second aspect.

[0053] The technical solution of this application will be further described below with reference to more specific embodiments.

[0054] Example 1 This application provides a perovskite solar cell, which includes a heterojunction base cell and a hole transport layer, a perovskite layer, a passivation layer, an electron transport layer, a buffer layer, a transparent conductive layer, a first electrode, and an antireflection layer disposed on the heterojunction base cell. A second electrode corresponding to the first electrode is also disposed on the base cell. All film layers disposed on the heterojunction base cell are grown conformally along the pyramidal textured surface structure of the heterojunction base cell. The fabrication method of each film layer on the heterojunction base cell includes the following steps: A carrier intermediate recombination layer with a thickness of 25 nm was prepared on a heterojunction bottom cell by magnetron sputtering. The material of the intermediate recombination layer was indium zinc oxide (IZO). A hole transport layer with a thickness of 25 nm and made of nickel oxide was prepared by magnetron sputtering on the side of the intermediate carrier recombination layer away from the heterojunction bottom cell. A perovskite layer with a thickness of 700 nm was fabricated on the side of the hole transport layer away from the heterojunction base cell. The perovskite layer was made of Cs material. 0.1 (FA 0.85 MA 0.15 ) 0.9 Pb(I 0.8 Br 0.15 Cl 0.05 3; On the side of the perovskite layer away from the heterojunction bottom cell, a passivation solution was spin-coated. The solutes of the passivation solution were DL-homocysteine ​​thiolactone hydrochloride, n-octylammonium iodide, and ethylenediamine dihydroiodide. The concentrations of DL-homocysteine ​​thiolactone hydrochloride, n-octylammonium iodide, and ethylenediamine dihydroiodide were 0.5 mg / mL and 1.7 mg / mL, respectively. The solvent was isopropanol. After spin-coating, annealing was performed at a temperature of 80℃~90℃ for 2 min~5 min. An electron transport layer was prepared by physical vapor deposition on the side of the passivation layer away from the heterojunction bottom cell. The material of the electron transport layer was C. 60 The thickness of the electron transport layer is 20 nm; In C 60 A tin oxide layer with a thickness of 25 nm was prepared on the side of the heterojunction bottom cell away from the layer using atomic vapor deposition. A transparent conductive layer with a thickness of 100 nm was fabricated by magnetron sputtering on the side of the tin oxide layer away from the heterojunction base cell. The material of the transparent conductive layer was indium tin oxide. A patterned first electrode with a thickness of 200 nm and made of silver was fabricated on the side of the transparent conductive layer away from the heterojunction bottom cell. An antireflection layer is deposited on the transparent conductive layer using an evaporation method. The antireflection layer is deposited in the region where the first electrode is not patterned, and the material is MgF2.

[0055] Example 2 This application provides a perovskite solar cell, which differs from Example 1 in that the concentration of DL-homocysteine ​​thiolactone hydrochloride in the passivation solution is 1 mg / mL, while the remaining steps are the same as in Example 1.

[0056] Example 3 This application provides a perovskite solar cell, which differs from Example 1 in that the concentration of DL-homocysteine ​​thiolactone hydrochloride in the passivation solution is 3 mg / mL, while the remaining steps are the same as in Example 1.

[0057] Comparative Example 1 This application provides a perovskite solar cell as a comparative example, which differs from Example 1 in that the passivation layer does not contain DL-homocysteine ​​thiolactone hydrochloride. Specifically, DL-homocysteine ​​thiolactone hydrochloride was not added to the passivation solution; only n-octylammonium iodide and ethylenediamine dihydroiodide were added, and the remaining steps were consistent with those in Example 1.

[0058] Comparative Example 2 This application provides a perovskite solar cell as a comparative example, which differs from Example 1 in that DL-homocysteine ​​thiolactone hydrochloride is replaced with L-cysteine ​​hydrochloride, while the rest remains the same as Example 1.

[0059] Experiment 1 XRD test The perovskite layers prepared in Example 1 and Comparative Example 1 were subjected to XRD tests, and the test results are shown in the figure. Figure 4 .

[0060] like Figure 4 As shown, compared with Comparative Example 1, the perovskite diffraction peak (i.e., the peak labeled PVSK) of Example 1 has a higher intensity, while the intensity of the lead iodide (PbI2) diffraction peak is lower, indicating that the introduction of DL-homocysteine ​​thiolactone hydrochloride into the passivation layer can improve the quality of the perovskite layer.

[0061] Experiment 2 The perovskite layers prepared in Example 1 and Comparative Example 1 were subjected to SEM testing. The SEM test results of Example 1 are shown in [Figure number missing]. Figure 5 The SEM test results for Comparative Example 1 are shown below. Figure 6 .

[0062] like Figure 5 and Figure 6 As shown, the perovskite layer of Example 1 is of better quality with no obvious impurities remaining, while the perovskite layer of Comparative Example 1 has obvious impurities ( Figure 6 The residue (shown as white in the image) indicates a low quality perovskite layer. This demonstrates that the introduction of DL-homocysteine ​​thiolactone hydrochloride can significantly improve the quality of the perovskite layer.

[0063] Experiment 3 Electrical performance testing The performance of the tandem solar cell was tested using the Wavelabs solar simulator under the following conditions: AM1.5, 1000 W / m². 2The test environment temperature was 25℃. Before the test, the intensity of the simulated sunlight was calibrated using a standard silicon cell.

[0064] The test results of the above embodiments and comparative examples are shown in Table 1.

[0065] Table 1

[0066] By comparing the data of Examples 1 to 3 with Comparative Example 1 in Table 1, it can be seen that the fill factor (FF) and power conversion efficiency (PCE) of Example 1 are significantly improved. This proves that by introducing DL-homocysteine ​​thiolactone hydrochloride into the passivation layer, the passivation effect of the perovskite layer surface can be effectively improved, which can further improve the performance of the solar cell.

[0067] Furthermore, a comparison of the data from Examples 1 to 3 with Comparative Example 2 shows that the fill factor and energy conversion efficiency of Example 1 are further improved compared to Comparative Example 2. This demonstrates that compared to adding flexible L-cysteine ​​hydrochloride, using cyclic DL-homocysteine ​​thiolactone hydrochloride can further passivate the surface defects of the perovskite layer, thereby achieving a further improvement in solar cell performance.

[0068] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A perovskite solar cell, characterized in that, It includes a perovskite layer and a passivation layer stacked on the surface of the perovskite layer, wherein the raw material for preparing the passivation layer includes a material containing a homocysteine ​​thiolactone structure.

2. The perovskite solar cell according to claim 1, characterized in that, The material containing a homocysteine ​​thiolactone structure contains a carbonyl group, a protonated amino group, and a thiol group, wherein the carbonyl group reacts with Pb in the perovskite layer. 2+ A Pb-O coordination bond is formed, the protonated amino group is bonded to the halogen vacancy in the perovskite layer via hydrogen bonding, and the thiol group is bonded to the Pb in the perovskite layer. 2+ Combine.

3. The perovskite solar cell according to claim 1, characterized in that, The material containing the homocysteine ​​thiolactone structure includes one or more combinations of DL-homocysteine ​​thiolactone hydrochloride, DL-homocysteine ​​thiolactone, D-homocysteine ​​thiolactone hydrochloride, and L-homocysteine ​​thiolactone hydrochloride. And / or, In the passivation layer, the mass percentage of the material containing the homocysteine ​​thiolactone structure is not less than 5%.

4. The perovskite solar cell according to claim 1, characterized in that, The passivation layer also includes one or two of n-octylammonium iodide and ethylenediamine dihydroiodide.

5. The perovskite solar cell according to claim 4, characterized in that, The passivation layer further includes the n-octylammonium iodide and the ethylenediamine dihydroiodide, wherein the mass ratio of the material containing the homocysteine ​​thiolactone structure, the mass of the n-octylammonium iodide, and the mass of the ethylenediamine dihydroiodide is (0.1~5):(1.5~2):(1.5~2).

6. The perovskite solar cell according to claim 1, characterized in that, The thickness of the passivation layer is 0.5 nm to 50 nm.

7. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell includes a perovskite single-junction solar cell or a perovskite tandem solar cell. The perovskite single-junction solar cell includes the following structure: A transparent conductive substrate and a first transport layer stacked on the transparent conductive substrate; The perovskite layer and the passivation layer are stacked sequentially on the side of the first transport layer away from the transparent conductive substrate; A second transport layer is stacked on the side of the passivation layer away from the transparent conductive substrate. One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer. A first electrode is disposed on the second transport layer, and a second electrode is disposed on the transparent conductive substrate; The perovskite tandem solar cell includes the following structure: A bottom battery and a carrier intermediate composite layer and a first transport layer sequentially stacked on the bottom battery; The perovskite layer and the passivation layer are stacked sequentially on the side of the first transport layer away from the bottom cell. The passivation layer is further stacked on the side away from the bottom battery, and one of the first transport layer and the second transport layer is an electron transport layer and the other is a hole transport layer. The second transmission layer has a transparent conductive layer stacked on the side opposite to the bottom battery; The transparent conductive layer is stacked on the side opposite to the bottom battery and has a first electrode.

8. A method for preparing a perovskite solar cell, characterized in that, Includes the following steps: A passivation solution is applied to the surface of a perovskite layer, followed by annealing to form a passivation layer on the surface of the perovskite layer. The passivation solution comprises a material containing a homocysteine ​​thiolactone structure.

9. The method for preparing a perovskite solar cell according to claim 8, characterized in that, In the passivation solution, the concentration of the material containing the homocysteine ​​thiolactone structure is from 0.1 mg / mL to 5 mg / mL; And / or, The passivation solution further includes n-octylammonium iodide and / or ethylenediamine dihydroiodide, wherein the concentration of n-octylammonium iodide is 1.5 mg / mL to 2 mg / mL, and the concentration of ethylenediamine dihydroiodide is 1.5 mg / mL to 2 mg / mL; And / or, In the step of preparing the passivation layer, the annealing temperature is 80℃~90℃ and the annealing time is 2 min~5 min; And / or, The passivation solution can be in the form of anhydrous ethanol or isopropanol.

10. A photovoltaic module, characterized in that, Includes the solar cell as described in any one of claims 1-7, or the solar cell prepared by the method described in any one of claims 8-9.

Images