Hole transport layer material and solar cell

Abstract

本申请提供了一种空穴传输层材料和太阳能电池，该空穴传输层材料包括如式（I）所示结构的化合物：R1~R4选自氢、卤素、氰基、硝基、羟基、取代或未取代的C1～C30烷基、取代或未取代的C3～C12环烷基、取代或未取代的C1～C30烷氧基、取代或未取代的C1～C30硅烷基、取代或未取代的C1~C30烷硫基；L1为取代或未取代的C6~C30亚芳基、取代或未取代的C3~C30亚杂芳基、取代或未取代的C1~C30亚烷基、取代或未取代的C1~C30亚烷氧基、取代或未取代的C1~C30亚烷硫基中的任意一种；R5、R6各自独立地选自卤素、取代或未取代的C1～C30烷基、取代或未取代的C3～C12环烷基、取代或未取代的C1～C30烷氧基、取代或未取代的C1～C30硅烷基、取代或未取代的C1~C30烷硫基、取代或未取代的C6~C30芳基。式（I）

Description

Technical Field

[0001] This application relates to the field of conductive materials technology, specifically to a hole transport layer material and a solar cell. Background Technology

[0002] Perovskite solar cells have advantages such as high photoelectric conversion efficiency and low-cost solution processing potential. Their photoelectric conversion efficiency is increasingly approaching that of crystalline silicon cells. Furthermore, the band gap of perovskite solar cells is adjustable, making them an ideal structure for constructing tandem solar cells.

[0003] In wide-bandgap perovskite solar cells, a high halogen ratio can easily lead to phase separation and open-circuit voltage loss. In perovskite solar cells, a hole transport layer is typically placed on one side of the perovskite light-absorbing layer, playing a crucial role in hole extraction, transport, and electron blocking. The hole transport layer also has a significant impact on the quality of the perovskite layer. Currently, the quality of perovskite thin films needs further improvement. Summary of the Invention

[0004] In view of this, in order to at least partially solve the aforementioned technical problems, this application provides a hole transport layer material and a solar cell.

[0005] According to one embodiment of this application, a hole transport layer material is provided, having a compound with the structure shown in formula (I): R1, R2, R3, and R4 represent monosubstituted to the most permissible substituents, each independently selected from hydrogen, halogen, cyano, nitro, hydroxyl, substituted or unsubstituted C1 to C4. 30 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C1-C 30 Silyl, substituted or unsubstituted C1~C 30 Alkylthio group; R5 and R6 are each independently selected from halogenated, substituted, or unsubstituted C1-C6 groups. 30 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C1-C 30 Silyl, substituted or unsubstituted C1~C 30 Alkylthio, substituted or unsubstituted C6~C 30 Aryl; L1 is substituted or unsubstituted C6~C 30 aryl, substituted or unsubstituted C3~C 30 Heteroaryl, substituted or unsubstituted C1~C 30 Alkylene, substituted or unsubstituted C1~C 30alkeneoxy, substituted or unsubstituted C1~C 30 Any one of the alkylthio groups; where the above-mentioned substituted or unsubstituted groups have substituents, the substituents are selected from halogens, hydroxyl groups, nitro groups, amino groups, C1~C1 groups. 12 Alkyl, C3~C 12 cycloalkyl, C1~C 12 Alkoxy, C1~C 12 One or a combination of at least two of the alkylthio groups.

[0006] Formula (I)

[0007] According to embodiments of this application, any two adjacent groups among R1, R2, R3, R4, R5, and R6 do not form a ring.

[0008] According to embodiments of this application, R1, R2, R3, and R4 are each independently selected from hydrogen, C1~C1. 12 Alkyl, C1~C 12 Alkoxy, C1~C 12 Any of the alkylthio groups, where R5 and R6 are each independently selected from C1 to C6. 12 Alkyl, substituted or unsubstituted C6~C 30 In the case of an aryl group, where the substituted or unsubstituted group has a substituent, the substituent is selected from C1 to C2. 12 Alkyl; L1 is C1~C 12 Alkylene, C1~C 12 alkeneoxy group, C1~C 12 alkylthionyl, C6~C 30 One of the aryl groups.

[0009] According to embodiments of this application, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, methyl, ethyl, isopropyl, and tert-butyl; R5 and R6 are each independently selected from any one of methyl, ethyl, isopropyl, and tert-butyl; L1 is C1~C 12 Alkylene or substituted or unsubstituted C6~C 30 arylene; where the above-mentioned substituted or unsubstituted groups have substituents, the substituents are selected from C1 to C2. 12 alkyl.

[0010] According to the embodiments of this application, R1, R2, R3, and R4 are all hydrogen; R5 and R6 are both methyl.

[0011] According to the embodiments of this application, L1 is C1~C 12 Straight-chain alkylene or phenylene.

[0012] According to embodiments of this application, the hole transport layer material has the following formulas (I1) to (I2).23 Compounds with the structure shown in the diagram:

[0013] Equation (I1) Equation (I2),

[0014] Equation (I3), Equation (I4)

[0015] Formula (I5) Equation (I6)

[0016] Equation (I7) Formula (I8)

[0017] Formula (I9) Formula (I 10 ),

[0018] Formula (I 11 ), Formula (I 12 ),

[0019] Formula (I 13 ), Formula (I 14 );

[0020] Formula (I 15 ), Formula (I 16 ),

[0021] Formula (I 17 ), Formula (I 18 ),

[0022] Formula (I 19 ), Formula (I 20 ),

[0023] Formula (I 21 ), Formula (I 22 ),

[0024] Formula (I 23 ).

[0025] According to another embodiment of this application, a solar cell is provided, comprising a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode layer stacked sequentially, wherein the hole transport layer comprises the hole transport layer material as described above.

[0026] According to an embodiment of this application, the perovskite light-absorbing layer includes perovskite material ABX3, where A includes one or more of cesium ions, rubidium ions, potassium ions, methylamine ions, formamidinium ions, methylenediamine ions, benzylamidinium cations, and guanidine cations; B includes one or more of lead ions and tin ions; and X includes one or more of chloride ions, bromide ions, and iodide ions.

[0027] According to an embodiment of this application, the substrate is a crystalline silicon bottom cell.

[0028] According to an embodiment of this application, the bandgap width of the solar cell is 1.6~1.8 eV.

[0029] According to the hole transport layer material provided in the embodiments of this application, the compound of formula (I) in the hole transport layer material has an asymmetric host structure of benzo[a]indene-carbazole fused rings, which is beneficial to improving the wettability of the perovskite precursor solution on the surface of the hole transport layer and promoting the high-quality growth of the perovskite thin film. In addition, the asymmetric host structure designed in this way significantly improves the solubility and film-forming properties of the hole transport layer material itself, and can better match with the perovskite light absorption layer, which is beneficial to hole transport. By further fused with other aromatic rings on the carbazole ring, the molecular rigidity is increased, which can increase the density of the hole transport layer material during self-assembly. In the subsequent formation of perovskite solar cells, it reduces lead vacancies and other defects, and enhances the passivation effect on perovskite interface defects. Attached Figure Description

[0030] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments of this application with reference to the accompanying drawings.

[0031] Figure 1 A cross-sectional view of a solar cell according to an embodiment of this application is shown;

[0032] Figure 2 The external quantum efficiency and current density curves of the perovskite solar cells of Application Example 3 and Comparative Application Example 1 of this application are shown.

[0033] Figure 3 The current density-voltage curves of the perovskite solar cells in Application Example 3 and Comparative Application Example 1 of this application are shown.

[0034] The meanings of the reference numerals in the above figures are as follows:

[0035] 1-Base;

[0036] 2-Hole transport layer;

[0037] 3-Perovskite light-absorbing layer;

[0038] 4-Electron transport layer;

[0039] 5-Electrode layer. Detailed Implementation

[0040] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0042] When using expressions such as "at least one of A, B or C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B or C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0043] In this application, the relative position between two components (e.g., a membrane or region), as referred to by terms such as "above," "on," or "above," can mean that the two components are in direct contact or that they are not in direct contact. Similarly, the relative position between two components, as referred to by terms such as "below," "under," or "below," can mean that the two components are in direct contact or that they are not in direct contact. For example, when one component (e.g., a membrane or region) is referred to as "on another component," it can be directly on the other component, or there may be other components between them. On the other hand, when a component is referred to as "directly on another component," there are no components between them. Furthermore, when one component is referred to as "on another component," the two components have a vertical relationship in the planar view, and this component can be above or below the other component, thus this vertical relationship depends on the orientation of the device.

[0044] Perovskite solar cells (PSCs) are a typical thin-film solar cell structure. Their core components include a perovskite light-absorbing layer, a hole transport layer (HTL), an electron transport layer (ETL), and electrode layers. Their working mechanism involves the perovskite light-absorbing layer absorbing photons, which induces valence band electrons to transition and form electron-hole pairs. Electrons enter the electron transport layer, and holes enter the hole transport layer. Driven by the built-in electric fields formed by electrodes with different work functions, they migrate to their respective electrodes, thereby outputting current.

[0045] Perovskite solar cells can be generated by tuning the band gap (E) of perovskite materials. g It can cover a voltage range of 1.18~2.3 eV, making it an ideal light-absorbing material for constructing tandem solar cells. Tandem solar cells are composed of wide-bandgap and narrow-bandgap sub-cells connected in series, with a theoretical efficiency potential approaching 40%. Therefore, developing efficient and stable wide-bandgap perovskite sub-cells is of crucial significance for realizing high-efficiency tandem devices.

[0046] Compared to conventional perovskite materials (E g Compared to perovskite materials with a wide bandgap (≈1.54 eV), perovskite materials with a higher halogen content are more prone to phase separation and thus have a higher open-circuit voltage (V). oc The loss is quite significant. Currently, the hole transport layer material widely used in related technologies is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), but PTAA has poor surface wettability and is not suitable for forming high-quality perovskite films.

[0047] In realizing the concept of this application, it was found that thin film materials containing phosphate groups as anchoring groups can be well adapted as hole transport materials to wide-bandgap perovskite solar cells, but the passivation effect at the perovskite interface is limited.

[0048] To address the aforementioned issues, this application utilizes an asymmetric benzo[a]indenocarbazole molecular structure, which enhances the wettability of the perovskite precursor solution on the hole transport layer surface, promoting high-quality perovskite film growth. Furthermore, this asymmetric host structure significantly improves the solubility and film-forming properties of the hole transport layer material itself, enabling better matching with the perovskite light-absorbing layer and facilitating hole transport. Further condensation with other aromatic rings on the carbazole ring increases molecular rigidity, allowing for increased density of the hole transport layer material during self-assembly. This reduces lead vacancies and other defects during subsequent perovskite solar cell formation, enhancing passivation of perovskite interface defects.

[0049] Specifically, according to one aspect of this application, a hole transport layer material is provided, having a structure as shown in formula (I):

[0050] Formula (I);

[0051] R1, R2, R3, and R4 represent monosubstituted to the most permissible substituents, each independently selected from hydrogen, halogen, cyano, nitro, hydroxyl, substituted or unsubstituted C1 to C4. 30 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C1-C 30 Silyl, substituted or unsubstituted C1~C 30 Alkylthio group; R5 and R6 are each independently selected from halogenated, substituted, or unsubstituted C1-C6 groups. 30 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C1-C 30 Silyl, substituted or unsubstituted C1~C 30 Alkylthio, substituted or unsubstituted C6~C 30 Aryl; L1 is substituted or unsubstituted C6~C 30 aryl, substituted or unsubstituted C3~C 30 Heteroaryl, substituted or unsubstituted C1~C 30 Alkylene, substituted or unsubstituted C1~C 30 alkeneoxy, substituted or unsubstituted C1~C 30 Any one of the alkylthio groups; where the above-mentioned substituted or unsubstituted groups have substituents, the substituents are selected from halogens, hydroxyl groups, nitro groups, amino groups, C1~C1 groups. 12 Alkyl, C3~C 12 cycloalkyl, C1~C 12 Alkoxy, C1~C 12 One or a combination of at least two of the alkylthio groups.

[0052] According to embodiments of this application, the hole transport layer material has a main structure of benzo[a]indenocarbazole fused rings, belonging to polycyclic aromatic fused rings. This continuously delocalized large π-conjugated system results in a high intrinsic hole mobility, enabling efficient extraction and transport of photogenerated holes generated by the perovskite light-absorbing layer. The left and right fused ring substitution units of the benzo[a]indenocarbazole fused ring have an asymmetric structure (one side is a naphthyl-type benzo[a]carbazole, and the other side is an indeno[a]benzene ring), which reduces the surface energy of the hole transport layer, resulting in a smaller spreading angle of the perovskite precursor solution on the hole transport layer, improved wettability, and further improved crystallinity of the perovskite. Meanwhile, this application fuses a benzene ring, an indene ring, and a carbazole tricyclic ring to form a highly rigid molecular framework. During self-assembly, the molecules are stacked in an orderly manner with strong π-π stacking interactions, which greatly improves the packing density of the hole transport layer. The dense hole transport layer film can effectively isolate external water and oxygen, while blocking the diffusion of lead ions from the perovskite light absorption layer, thereby reducing lead vacancies and interfacial recombination, and effectively passivating the interfacial defects of the perovskite.

[0053] It should be noted that since neither R5 nor R6 is hydrogen, it helps to improve the molecular stability of the hole transport layer material.

[0054] In this application, "R1, R2, R3, R4 represent single substituents to the maximum permissible substituents" can be understood as R1~R4 each independently representing a single substituent, attached to any connectable position on the ring structure to which it is attached; R1~R4 can also each be several substituents, in which case the number of substituents in R1~R4 can be the same or different, and the several substituents on the same ring structure can be the same or different. For example, there can be 2 R4s, in which case the 2 R4s can be the same or different from each other.

[0055] In this application, the "substituted or unsubstituted" group mentioned above can replace one substituent or multiple substituents. When there are multiple substituents, they can be selected from different substituents. When the same expression is used in this application, they all have the same meaning, and the selection range of substituents is as shown above and will not be repeated one by one.

[0056] In this specification, C a ~C b The expression indicates that the group has a to b number of carbon atoms. Unless otherwise specified, this number of carbon atoms generally does not include the number of carbon atoms of the substituents.

[0057] In this specification, "each independently" means that when there are multiple subjects, they may be the same or different from each other.

[0058] In this specification, unless otherwise specified, the description of chemical elements usually includes the concept of their isotopes. For example, the description of "hydrogen (H)" includes the concept of its isotopes 1H (protium or H) and 2H (deuterium or D); carbon (C) includes 12C, 13C, etc., which will not be elaborated further.

[0059] In this application, heteroatoms generally refer to atoms or groups of atoms selected from N, O, S, P, Si and Se, preferably selected from N, O and S.

[0060] Examples of halogens in this specification include fluorine, chlorine, bromine, and iodine.

[0061] In this application, aryl refers to both monocyclic aryl and fused-ring aryl groups. Monocyclic aryl refers to a molecule containing one or at least two phenyl groups. When a molecule contains at least two phenyl groups, the phenyl groups are independent of each other and connected by single bonds, such as phenyl, diphenyl, and terphenyl. Fused-ring aryl refers to a molecule containing at least two benzene rings, but the benzene rings are not independent of each other; instead, they are fused together by sharing ring edges, such as naphthyl and anthracene.

[0062] In this specification, C6 to C 30 Examples of aryl groups include: phenyl, naphthyl, anthracene, benzo[a]anthrayl, phenanthryl, benzo[a]phenanthryl, pyrene, pyryl, peryl, fluoranthyl, tetraphenyl, pentaphenyl, benzo[a]pyrene, biphenyl, azophenyl, terphenyl, triphenyl, tetraphenyl, fluorenyl, spirodifluorenyl, dihydrophenanthryl, dihydropyrene, tetrahydropyrene, cis or trans indo[a]fluorenyl, trimerinyl, isotriterinyl, spirotriterinyl, and spiroisotriterinyl groups in the group consisting of phenyl, naphthyl, anthracene, benzo[a]fluorenyl, spiro[a]isotriterinyl, and spiro[a]isotriterinyl groups. Specifically, biphenyl is selected from 2-biphenyl, 3-biphenyl, and 4-biphenyl; terphenyl includes p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, meta-terphenyl-4-yl, meta-terphenyl-3-yl, and meta-terphenyl-2-yl; naphthyl includes 1-naphthyl or 2-naphthyl; anthracene is selected from 1-anthrayl, 2-anthrayl, and 9-anthraylene; fluorenyl is selected from 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl, and 9-fluorenyl; pyrene is selected from 1-pyrene, 2-pyrene, and 4-pyrene; and tetraphenyl is selected from 1-terphenyl, 2-terphenyl, and 9-terphenyl.

[0063] In this specification, C3 to C 30Examples of heteroaryl groups include nitrogen-containing heteroaryl groups, oxygen-containing heteroaryl groups, and sulfur-containing heteroaryl groups. Specific examples include: pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, isoquinolinyl, naphthidyl, phthalazinyl, quinoxalinyl, quinazolinyl, phenanthridine, acridineyl, phenanthroxolinyl, pyrroleyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, indoleyl, benzimidazolyl, indazolyl, imidazopyridyl, benzo[[]] Triazolyl, carbazole, furanyl, thiophene, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, thiazolyl, benzofuranyl, benzothiophene, benzooxazolyl, benzothiazolyl, benzoisooxazolyl, benzoisothiazolyl, benzooxadiazolyl, dibenzofuranyl, dibenzothiaphene, piperidinyl, pyrrolylyl, piperazine, morpholinyl, phenazinyl, phenthiazinyl, phenoxazinyl, etc.

[0064] Specific examples of aryl groups in this application can be exemplified by removing one hydrogen atom from the aforementioned aryl examples to obtain a divalent group. Specific examples of heteroaryl groups in this application can be exemplified by removing one hydrogen atom from the aforementioned heteroaryl examples to obtain a divalent group.

[0065] In this specification, C1 to C 30 Examples of alkyl groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecane, dodecane, etc.

[0066] Furthermore, one or more of R1, R2, R3, R4, R5, and R6 are C1~C 30 In the case of alkyl groups, the C1-C 30 Alkyl groups are preferably methyl and ethyl.

[0067] In L1, C1~C 30 In the case of alkylene groups, the C1-C 30 The alkylene group is preferably n-butylene.

[0068] In this specification, C1~C 30 Examples of alkoxy groups include: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, pentooxy, isopentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, undecyloxy, dodecyloxy, etc., among which methoxy, ethoxy, n-propoxy, isopropoxy, tert-butoxy, sec-butoxy, isobutoxy, and isopentoxy are preferred, and methoxy and ethoxy are more preferred.

[0069] In this specification, C1~C 30 Examples of alkoxy groups can be found above, where the oxygen is replaced by sulfur.

[0070] Specific examples of alkeneoxy groups in this application can be exemplified by removing one hydrogen atom from the aforementioned alkeneoxy groups to obtain a divalent group. Specific examples of alkenethio groups in this application can be exemplified by removing one hydrogen atom from the aforementioned alkanethio groups to obtain a divalent group.

[0071] In this specification, C3~C 12 Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0072] In some embodiments, any two adjacent groups among R1, R2, R3, R4, R5, and R6 do not form a ring. This maintains the specific extended conjugated structure of the existing benzo[a]indo[a]carbazole fused ring, resulting in a high intrinsic hole mobility in the formation of a continuously delocalized large π-conjugated system. It also increases the density of the monomolecular self-assembled layer, improving the passivation effect on perovskite films, while avoiding a decrease in the solubility of the compound of formula (I) due to an excessively large conjugated surface.

[0073] In some embodiments, R1, R2, R3, and R4 are each independently selected from hydrogen, C1 to C2, C3, C4 ... 12 Alkyl, C1~C 12 Alkoxy, C1~C 12 Any of the alkylthio groups, where R5 and R6 are each independently selected from C1 to C6. 12 Alkyl, substituted or unsubstituted C6~C 30 In the case of an aryl group, where the substituted or unsubstituted group has a substituent, the substituent is selected from C1 to C2. 12 Alkyl; L1 is C1~C 12 Alkylene, C1~C 12 alkeneoxy group, C1~C 12 alkylthionyl, C6~C 30 One type of aryl group. This allows for the appropriate fine-tuning of the HOMO and LUMO energy levels of the benzo[a]indenocarbazole fused ring without introducing additional conjugated structures that would affect the asymmetric structure of the hole transport layer material. This facilitates energy level matching with the perovskite light-absorbing layer, further enhancing the photoelectric performance of the perovskite solar cell. Furthermore, the selected L1 group is more beneficial for improving the solubility and film-forming properties of the hole transport layer material.

[0074] In some embodiments, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, methyl, ethyl, isopropyl, and tert-butyl; R5 and R6 are each independently selected from any one of methyl, ethyl, isopropyl, and tert-butyl; L1 is C1~C 12 Alkylene or substituted or unsubstituted C6~C 30arylene; where the above-mentioned substituted or unsubstituted groups have substituents, the substituents are selected from C1 to C2. 12 Alkyl groups. This further helps to improve the film-forming properties of the hole transport layer material while maintaining good wettability on the hole transport layer surface, thus promoting the growth of high-quality perovskite films on its surface.

[0075] It is understandable that setting the same R5 and R6 symmetrically helps to further enhance the molecular stability of the hole transport layer material.

[0076] In some embodiments, R1, R2, R3, and R4 are all hydrogen; and R5 and R6 are both methyl groups.

[0077] In some implementations, L1 is C1~C 12 Straight-chain alkylene or phenylene compounds. This further enhances the performance of the resulting perovskite solar cells.

[0078] In some specific embodiments, the hole transport layer material has the following formulas (I1) to (I2) 23 Compounds with the structure shown in the diagram:

[0079] Equation (I1) Equation (I2),

[0080] Equation (I3), Equation (I4)

[0081] Formula (I5) Equation (I6)

[0082] Equation (I7) Formula (I8)

[0083] Formula (I9) Formula (I 10 ),

[0084] Formula (I 11 ), Formula (I 12 ),

[0085] Formula (I 13 ), Formula (I 14 );

[0086] Formula (I 15 ), Formula (I16 ),

[0087] Formula (I 17 ), Formula (I 18 ),

[0088] Formula (I 19 ), Formula (I 20 ),

[0089] Formula (I 21 ), Formula (I 22 ),

[0090] Formula (I 23 It is understood that the aforementioned hole transport layer material can be prepared using common methods in the field. Moreover, the preparation methods for the aforementioned hole transport layer material are simple, have low preparation costs, and the intermediates used in the preparation process are widely available and low in cost. The synthesis routes are flexible and diverse, providing multiple possibilities for realizing high-performance and low-cost hole transport materials, and have significant application prospects.

[0091] Specifically, taking the structure shown in formula (I1) as an example, this application schematically illustrates the preparation process of the above-mentioned hole transport layer material. It can be understood that this preparation process is prepared in a conventional manner in the art, and the preparation method of this application does not constitute a special limitation on the preparation process of the above-mentioned material.

[0092] (1) Under the catalysis of 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride and potassium acetate, 4-bromo-9,9'-dimethylfluorene (1a) and bis(pinacol)diboron undergo a first coupling reaction with toluene as the reaction solvent to generate compound 1b.

[0093] Its preparation process can be as follows:

[0094] .

[0095] In some embodiments, the molar equivalent of bis(pinacol)diboron relative to 4-bromo-9,9'-dimethylfluorene (1a) can be 1 to 15 eq, preferably 1 to 10 eq, and more preferably 1 to 5 eq. The molar equivalents of 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride and potassium acetate relative to 4-bromo-9,9'-dimethylfluorene (1a) are 0.05 eq and 5 eq, respectively.

[0096] In some embodiments, the temperature of the first coupling reaction can be 100~120°C, preferably 110°C, and the reaction time can be 5~20 hours, preferably 5~15 hours, more preferably 10~15 hours.

[0097] In some embodiments, after the first coupling reaction is completed, a first post-treatment is also performed, which specifically includes: natural cooling to room temperature, washing with water, extraction with dichloromethane, drying with anhydrous magnesium sulfate, removing the solvent by rotary evaporation, and purification by silica gel column chromatography using a petroleum ether / dichloromethane mixture with a volume ratio of 9:1 to obtain the purified compound 1b.

[0098] (2) Under the catalysis of tetra(triphenylphosphine)palladium and potassium carbonate, and with toluene as the reaction solvent, compound 1b undergoes a second coupling reaction with 1-bromo-2-nitronaphthalene to generate compound 1c.

[0099] Its preparation process can be as follows:

[0100] .

[0101] In some embodiments, the molar equivalent of 4-bromo-3-nitrobenzene ether relative to compound 1b can be 1 to 15 eq, preferably 1 to 10 eq, and more preferably 1 to 5 eq. The molar equivalents of tetra(triphenylphosphine)palladium and potassium carbonate relative to compound 1b are 0.05 eq and 5 eq, respectively.

[0102] In some embodiments, similar to the first coupling reaction, the temperature of the second coupling reaction can be 100~120°C, preferably 110°C, and the reaction time can be 5~20 hours, preferably 5~15 hours, more preferably 10~15 hours.

[0103] In some embodiments, after the second coupling reaction is completed, a second post-processing is also performed, which specifically includes: natural cooling to room temperature, washing with water, extraction with dichloromethane, drying with anhydrous magnesium sulfate, removing the solvent by rotary evaporation, and purification by silica gel column chromatography using a petroleum ether / dichloromethane mixture with a volume ratio of 7:1 to obtain the purified compound 1c.

[0104] (3) Using o-dichlorobenzene as the reaction solvent, compound 1c is reacted with triphenylphosphine to form compound BICz.

[0105] Its preparation process can be as follows:

[0106] .

[0107] In some embodiments, the molar equivalent of triphenylphosphine relative to compound 1c can be 1 to 30 eq, preferably 1 to 10 eq, and more preferably 1 to 5 eq.

[0108] In some embodiments, the cyclization reaction temperature is 170~190°C, preferably 180°C, and the reaction time is 5~20 hours, preferably 5~15 hours, and more preferably 10~15 hours.

[0109] In some embodiments, after the cyclization reaction is completed, a third post-treatment is also included, specifically including: natural cooling to room temperature, rotary evaporation to remove the solvent, and silica gel column chromatography purification using a petroleum ether / dichloromethane mixture with a volume ratio of 3:1 to obtain the purified compound BICz.

[0110] (4) Under the catalysis of potassium hydroxide aqueous solution and tetrabutylammonium bromide, compound BICz undergoes a third coupling reaction with 1,4-dibromobutane to generate compound 2a.

[0111] Its preparation process can be as follows:

[0112] .

[0113] In some embodiments, the molar equivalent of 1,4-dibromobutane relative to BICz can be 1~30 eq, preferably 10~30 eq, more preferably 15~20 eq. The tetrabutylammonium bromide and the aqueous potassium hydroxide solution contain potassium hydroxide with a molar equivalent of 2.0 eq and 5 eq relative to compound BICz, respectively, and the mass concentration of the potassium hydroxide solution can be 50%. 1,4-dibromobutane acts as both a reactant and a solvent, and tetrabutylammonium bromide acts as a phase transfer catalyst.

[0114] In some embodiments, the temperature of the third coupling reaction is 50-70°C, preferably 60°C, and the reaction time is 5-20 hours, preferably 5-15 hours, and more preferably 10-15 hours.

[0115] In some embodiments, after the third coupling reaction is completed, a fourth post-treatment is also included, which specifically includes: natural cooling to room temperature, washing with water, extraction with dichloromethane, drying with anhydrous magnesium sulfate, removing the solvent by rotary evaporation, and purification by silica gel column chromatography using a petroleum ether / dichloromethane mixture with a volume ratio of 3:1 to obtain the purified compound 2a.

[0116] (5) Under nitrogen protection, compound 2a undergoes a first esterification reaction with triethyl phosphite to generate compound 2b.

[0117] Its preparation process can be as follows:

[0118] .

[0119] In some embodiments, the molar equivalent of triethyl phosphite to compound 2a can be 5 to 30 eq, preferably 10 to 20 eq, and more preferably 15 to 20 eq. Triethyl phosphite is used as both a reactant and a solvent.

[0120] In some embodiments, the temperature of the first esterification reaction is 160-180°C, preferably 170°C, and the reaction time is 10-30 hours, preferably 10-20 hours, and more preferably 15-20 hours.

[0121] In some embodiments, after the first esterification reaction is completed, a fifth post-treatment is also performed, which specifically includes: natural cooling to room temperature, removing the solvent by vacuum distillation, and purification by silica gel column chromatography using a 3:1 volume ratio of dichloromethane / ethyl acetate mixture to obtain the purified compound 2b.

[0122] (6) Under nitrogen protection, using ultra-dry 1,4-dioxane as the reaction solvent, compound 2b undergoes a first hydrolysis reaction with trimethylbromosilane to produce the compound shown in formula (I1) (abbreviated as compound BICzPA).

[0123] Its preparation process can be as follows:

[0124] .

[0125] In some embodiments, the molar equivalent of trimethylbromosilane relative to compound 2b can be 1 to 20 eq, preferably 1 to 15 eq, and more preferably 10 to 15 eq.

[0126] In some embodiments, the specific process of the first hydrolysis reaction may be as follows: under a nitrogen atmosphere, compound 2b is dissolved in anhydrous 1,4-dioxane, and trimethylbromosilane is added dropwise. The mixture is stirred at room temperature for 24 hours, and then methanol is added. The mixture is stirred at room temperature for another 3 hours to achieve the quenching reaction.

[0127] In some embodiments, after the first hydrolysis reaction is completed, a sixth post-treatment is also included, which specifically includes: removing part of the solvent by rotary evaporation, adding methanol, then adding distilled water dropwise until the solution is opaque, stirring for 12 hours, filtering to collect the solid, washing with water, and obtaining the purified BICzPA.

[0128] Furthermore, taking the structure shown in formula (I9) as an example, based on the foregoing content, this application schematically illustrates a further preparation process. It can be understood that, similar to the foregoing, this preparation process is obtained in a conventional manner in the art, and the preparation method of this application does not constitute a special limitation on the preparation process of the above materials.

[0129] (7) Under nitrogen protection, with toluene as the reaction solvent, compound BICzPA and p-diiodobenzene undergo a fourth coupling reaction in the presence of cuprous iodide, potassium phosphate, and (1S)-trans-1,2-cyclohexanediamine to generate compound 3a.

[0130] Its preparation process can be as follows:

[0131] .

[0132] In some embodiments, the molar equivalent of diiodobenzene relative to compound BICz can be ~10 eq, preferably 2~8 eq, and more preferably 3~6 eq. The molar equivalents of cuprous iodide, potassium phosphate, and trans-1,2-cyclohexanediamine relative to compound BICz are 0.5 eq, 3.0 eq, and 0.5 eq, respectively.

[0133] In some embodiments, the temperature of the fourth coupling reaction is 100-120°C, preferably 110°C, and the reaction time is 5-20 hours, preferably 5-15 hours, and more preferably 10-15 hours.

[0134] In some embodiments, after the fourth coupling reaction is completed, the mixture is naturally cooled to room temperature, washed with water, extracted with dichloromethane, dried with anhydrous magnesium sulfate, the solvent is removed by rotary evaporation, and purified by silica gel column chromatography using a petroleum ether / dichloromethane mixture at a volume ratio of 3:1 to obtain the purified compound 3a.

[0135] (8) Under nitrogen protection, with toluene as the reaction solvent, compound 3a reacts with diethyl phosphite in a second esterification reaction catalyzed by tetra(triphenylphosphine)palladium and triethylamine to generate compound 3b.

[0136] Its preparation process can be as follows:

[0137] .

[0138] In some embodiments, the molar equivalent of diethyl phosphite to compound 3a can be 1 to 15 eq, preferably 1 to 10 eq, and more preferably 1 to 5 eq. The molar equivalents of tetra(triphenylphosphine)palladium and triethylamine to compound 3a are 0.05 eq and 1.2 eq, respectively.

[0139] In some embodiments, the temperature of the second esterification reaction is 100-120°C, preferably 110°C, and the reaction time is 5-20 hours, preferably 5-15 hours, and more preferably 10-15 hours.

[0140] In some embodiments, after the second esterification reaction is completed, an eighth post-treatment is also performed, which specifically includes: natural cooling to room temperature, washing with water, extraction with dichloromethane, drying with anhydrous magnesium sulfate, removing the solvent by rotary evaporation, and purification by silica gel column chromatography using a 3:1 volume ratio of dichloromethane / ethyl acetate mixture to obtain the purified compound 3b.

[0141] (9) Under nitrogen protection, with anhydrous 1,4-dioxane as the reaction solvent, compound 3b undergoes a second hydrolysis reaction with trimethylbromosilane to produce the compound shown in formula (I9) (abbreviated as compound BICz-PhPA).

[0142] Its preparation process can be as follows:

[0143] .

[0144] In some embodiments, the molar equivalent of trimethylbromosilane relative to compound 3b can be 1 to 20 eq, preferably 1 to 15 eq, and more preferably 10 to 15 eq.

[0145] In some embodiments, the specific process of the second hydrolysis reaction may be as follows: first, under a nitrogen atmosphere, compound 3b is dissolved in anhydrous 1,4-dioxane, and trimethylbromosilane is added dropwise, the reaction is stirred at room temperature for 24 hours, methanol is added, and the reaction is continued to be stirred at room temperature for 3 hours to achieve the quenching reaction.

[0146] In some embodiments, after the second hydrolysis reaction is completed, a ninth post-treatment is also performed, which specifically includes: removing part of the solvent by rotary evaporation, adding methanol, then adding distilled water dropwise until the solution is opaque, stirring for 12 hours, filtering to obtain the solid, washing with water, and obtaining the purified BICz-PhPA.

[0147] According to another embodiment of this application, a solar cell is provided. Figure 1 A cross-sectional view of a solar cell according to an embodiment of this application is shown, such as... Figure 1 As shown, the solar cell comprises, from bottom to top, a substrate 1, a hole transport layer 2, a perovskite light-absorbing layer 3, an electron transport layer 4, and an electrode layer 5, which are stacked sequentially. The hole transport layer 2 comprises the hole transport layer material as described above.

[0148] According to embodiments of this application, a hole transport layer 2 is formed using a hole transport material comprising the aforementioned asymmetric benzo[a]indene-carbazole fused ring structure. Because the hole transport material possesses the aforementioned technical effects, the efficiency of the solar cell can be improved. In some preferred embodiments, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, methyl, ethyl, isopropyl, and tert-butyl; R5 and R6 are simultaneously any one of methyl, ethyl, isopropyl, and tert-butyl; L1 is C1~C1.12 When linear alkylene or phenylene chains are used, the wettability of the hole transport layer 2 surface can be improved, as well as the film uniformity of the hole transport layer 2 surface, which is more conducive to the fabrication of large-area perovskite solar cells.

[0149] In some embodiments, the hole transport layer 2 can be prepared by spin coating, and its thickness can be 1~5 nm.

[0150] In some embodiments, the concentration of the solution forming the hole transport layer can be 0.1 to 0.6 mg / mL, for example, 0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.4 mg / mL, 0.5 mg / mL, or 0.6 mg / mL, or a range consisting of any two of the above values. Preferably, it is 0.2 to 0.5 mg / mL.

[0151] In some embodiments, the perovskite light-absorbing layer includes a perovskite material ABX3, where A includes one or more of cesium ions, rubidium ions, potassium ions, methylamine ions, formamidinium ions, methylenediamine ions, benzylamidinium cations, and guanidine cations; B includes one or more of lead ions and tin ions; and X includes one or more of chloride ions, bromide ions, and iodide ions.

[0152] In some further embodiments, A includes one or more of methylamine ions and formamidinium ions; B is lead ions; and X is selected from one or more of chloride ions, bromide ions, and iodide ions. The hole transport layer material described above, combined with the screened perovskite light-absorbing layer 3, can significantly improve the wettability of the hole transport layer surface, resulting in a more uniform spread of the perovskite precursor solution. Consequently, the perovskite light-absorbing layer 3 film formed by self-assembly on the substrate is more uniform and dense, exhibiting strong stability when subjected to solvent washing or thermal stress.

[0153] In some embodiments, the electron transport layer 4 is made of one or more of the following materials: zinc oxide, tin oxide, titanium dioxide, strontium titanate, zinc stannate, zirconium dioxide, aluminum oxide, tungsten trioxide, cesium oxide, cadmium sulfide, cadmium selenide, barium stannate, niobium pentoxide, C60, and fullerenes and fullerene derivatives including PCBM. For example, a C60 electron transport layer can be prepared by thermal evaporation deposition, with a thickness of 15-30 nm. A tin oxide electron transport layer can be prepared by atomic layer deposition (ALD) technology, with a thickness of 15-20 nm.

[0154] In some embodiments, the hole transport layer 2 and the electron transport layer 4 may also include other functional films suitable for improving carrier transport performance, such as insulating layers, barrier layers, buffer layers, etc. Since these are not key aspects of this application and are well-known technologies in the art, they will not be listed here.

[0155] In some embodiments, electrode layer 5 may be, for example, a silver electrode.

[0156] In some embodiments, substrate 1 is a crystalline silicon bottom cell. Thus, a perovskite top cell is located on the crystalline silicon bottom cell. The crystalline silicon bottom cell can be a monocrystalline silicon cell such as PERC, BC, or TOPCON, or a thin-film polycrystalline silicon cell; this application does not impose any particular limitation.

[0157] According to embodiments of this application, since the hole transport layer 2 in the perovskite top cell uses the aforementioned specific benzo[a]indenocarbazole fused ring asymmetric structure, its greater molecular rigidity allows for increased density and reduced defects during self-assembly, resulting in better energy level matching with the perovskite light-absorbing layer 3. Furthermore, its asymmetry facilitates surface wettability, thereby promoting the growth of high-quality perovskite thin films. This helps improve the cell performance, such as open-circuit voltage, of tandem solar cells composed of a crystalline silicon bottom cell and a perovskite top cell.

[0158] In some embodiments, the bandgap width of the solar cell is 1.6~1.8 eV. It is understood that compared to the bandgap width of conventional perovskite materials (around 1.54 eV), wide-bandgap solar cells (i.e., 1.6~1.8 eV) have a relatively higher halogen content, are more prone to phase separation, and result in significant open-circuit voltage loss. During the growth of the perovskite thin film, the surface wettability of the hole transport layer 2 has a significant impact on the film quality. The asymmetric structure of the hole transport layer material with anchoring groups in this application can improve the surface wettability of the hole transport layer 2, while enhancing the passivation effect on perovskite interface defects, which is more conducive to the formation of a high-quality perovskite thin film, thereby improving the cell performance of the solar cell.

[0159] According to embodiments of this application, the battery body of the perovskite top solar cell may further include an antireflection layer. The antireflection layer may be made of one of lithium fluoride (LiF), magnesium fluoride (MgF2), aluminum nitride (AlN), zinc sulfide (ZnS), silicon nitride (Si3N4), silicon oxide (SiO2), and titanium oxide (TiO2), and its thickness is 0-3 mm. In this case, the electrode passes through the antireflection layer to contact the electrode layer.

[0160] According to embodiments of this application, the tandem solar cell may further include a composite layer located between the crystalline silicon bottom cell and the perovskite top cell. The composite layer primarily serves to connect the crystalline silicon bottom cell and the perovskite top cell, ensuring effective recombination of majority carriers. The composite layer may be, for example, one of a tunnel junction, indium zinc oxide (IZO), indium tin oxide (ITO), or aluminum-doped zinc oxide (AZO). Of course, in other embodiments, a composite layer may be omitted.

[0161] According to the embodiments of this application, the ultraviolet-visible absorption spectrum shows that the hole transport layer material has a large optical bandgap, and can achieve a photoelectric conversion efficiency of more than 21.97% in an inverted wide bandgap perovskite solar cell (pin), showing great application prospects.

[0162] According to another embodiment of this application, a photovoltaic module is provided, comprising: a plurality of the aforementioned solar cells. The plurality of the aforementioned solar cells (which may be the aforementioned solar cells or the aforementioned tandem solar cells) are connected in series to form a solar cell string; and an encapsulation structure covering the surface of the solar cell string.

[0163] According to embodiments of this application, the number of solar cells connected in series can be 4 to 20. Multiple solar cells can form several solar cell strings, each containing the same number of solar cells. The solar cell strings can be connected in series or in parallel.

[0164] According to embodiments of this application, the encapsulation structure may include a backplate, an encapsulating film, a glass panel, etc., to improve the stability of the solar cell string. The glass panel is located on the front of the solar cell string, and the backplate is located on the back of the solar cell string, both serving a protective function. The adhesive film is the adhesive film between the solar cell string and the glass panel and backplate, serving a bonding and fixing function; the adhesive film on the front side must be made of a transparent material.

[0165] The present application is further illustrated below through embodiments, accompanying drawings, and related test experiments and results. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0166] It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this application is not limited thereto. The chemicals and raw materials used in the following embodiments are all commercially available or prepared using recognized processing methods.

[0167] Example 1: Synthesis of the compound shown in formula (I1)

[0168] The overall synthesis route is shown below:

[0169] .

[0170] (1) Synthesis of compound 1b:

[0171]

[0172] In a 100 mL two-necked flask, the reactants 4-bromo-9,9'-dimethylfluorene (1a) (2 g, 7.32 mmol), bis(pinacol)diboron (2.79 g, 10.98 mmol), 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride (0.268 g, 0.37 mmol), and potassium acetate (3.59 g, 36.61 mmol) were dissolved in 15 mL of toluene. The mixture was evacuated under nitrogen several times, heated to 110 °C, refluxed, and reacted overnight. After confirming the completeness of the reaction by thin-layer chromatography (TLC), the reaction mixture was cooled to room temperature, washed with water, and extracted with dichloromethane. The resulting organic phase was dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The solution was purified by silica gel column chromatography using petroleum ether / dichloromethane (9:1, V / V) as the eluent to give a white solid 1b (1.93 g, 82%).

[0173] (2) Synthesis of compound 1c:

[0174] .

[0175] In a 100 mL two-necked flask, compound 1b (1.93 g, 6.03 mmol), 1-bromo-2-nitronaphthalene (1.68 g, 7.23 mmol), and potassium carbonate (4.16 g, 30.13 mmol) were dissolved in 15 mL of toluene. The mixture was evacuated under nitrogen several times, and tetrakis(triphenylphosphine)palladium (0.35 g, 0.30 mmol) was added. The mixture was heated to 110 °C, refluxed, and reacted overnight. After confirming complete reaction by TLC, the reaction mixture was cooled to room temperature, washed with water, and extracted with dichloromethane. The resulting organic phase was dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The solution was purified by silica gel column chromatography using petroleum ether / dichloromethane (7:1, V / V) as the eluent to give a yellow solid 1c (1.90 g, 92%).

[0176] (3) Synthesis of compound BICz:

[0177] .

[0178] Compound 1c (1.90 g, 5.50 mmol) and triphenylphosphine (3.61 g, 13.75 mmol) were dissolved in 10 mL of o-dichlorobenzene in a 100 mL two-necked flask. The mixture was evacuated and purged with nitrogen several times, heated to 180 °C, refluxed, and reacted overnight. After confirming the completeness of the reaction by thin-layer chromatography, the reaction mixture was cooled to room temperature, washed with water, and extracted with dichloromethane. The resulting organic phase was dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The solution was purified by silica gel column chromatography using petroleum ether / dichloromethane (3:1, V / V) as the eluent to give a white solid BICz (0.93 g, 54%), mass spectrometry (m / z): 334.15 [M+H]. + .

[0179] (4) Synthesis of compound 2a:

[0180] .

[0181] In a 100 mL reaction tube, the starting material BICz (1.0 g, 3.19 mmol), 1,4-dibromobutane (5.50 mL, 63.86 mmol), tetrabutylammonium bromide (0.21 g, 0.65 mmol), and 2.2 mL of 50% potassium hydroxide aqueous solution were added sequentially. The mixture was heated to 60°C and reacted overnight. After confirming the completeness of the reaction by thin-layer chromatography, the reaction mixture was cooled to room temperature, washed with water, and then extracted with dichloromethane. The resulting organic phase was dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The solution was purified by silica gel column chromatography using petroleum ether / dichloromethane (3:1, V / V) as the eluent to give a white solid 2a (1.33 g, 82%).

[0182] (5) Synthesis of compound 2b:

[0183] .

[0184] In a 100 mL reaction tube, reactant 2a (1 g, 2.23 mmol) was dissolved in triethyl phosphite (8.6 mL). The mixture was evacuated and purged with nitrogen several times, and then refluxed in a sand bath at 170°C for 16 h. After confirming the completeness of the reaction by thin-layer chromatography, the mixture was cooled to room temperature, and the solvent was removed by vacuum distillation. The mixture was then purified by silica gel column chromatography using dichloromethane / ethyl acetate (3:1, V / V) as the eluent to obtain a syrupy liquid 2b (0.95 g, 84%).

[0185] (6) Synthesis of the compound shown in formula (I1) (abbreviated as BICzPA):

[0186] .

[0187] Compound 2b (0.4 g, 0.79 mmol) was dissolved in anhydrous 1,4-dioxane (10 mL) under a nitrogen atmosphere, and trimethylbromosilane (1.82 g, 11.9 mmol) was added dropwise. After reacting at room temperature for 24 h, 5 mL of methanol was added and stirring continued for 3 h. Partial solvent was removed by rotary evaporation, followed by the addition of 5 mL of methanol, and then distilled water was added dropwise until the solution became opaque. The mixture was stirred overnight. The product was filtered off, washed with water, and dried to give a white solid BICzPA (0.28 g, 78%). Mass spectrometry (m / z): 470.18 [M+H] + .

[0188] Example 2:

[0189] The further synthesis route based on Example 1 is as follows:

[0190]

[0191] (1) Synthesis of compound 3a:

[0192] .

[0193] In a 100 mL two-necked flask, the reactants BICz (0.3 g, 0.96 mmol), p-diiodobenzene (0.95 g, 2.97 mmol), trans-1,2-cyclohexanediamine (0.05 g, 0.48 mmol), cuprous iodide (0.09 g, 0.48 mmol), and potassium phosphate (0.6 g, 2.87 mmol) were dissolved in 15 mL toluene. The mixture was evacuated under nitrogen several times, heated to 110 °C, refluxed, and reacted overnight. After confirming the completeness of the reaction by thin-layer chromatography, the reaction mixture was cooled to room temperature, washed with water, and extracted with dichloromethane. The resulting organic phase was dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The solution was purified by silica gel column chromatography using petroleum ether / dichloromethane (3:1, V / V) as the eluent to give a pale yellow solid 3a (0.40 g, 81%).

[0194] (2) Synthesis of compound 3b:

[0195] .

[0196] In a 100 mL two-necked flask, compound 3a (0.4 g, 0.77 mmol), diethyl phosphite (0.2 g, 1.55 mmol), and triethylamine (0.09 g, 0.93 mmol) were dissolved in 15 mL of toluene. The mixture was evacuated under nitrogen several times, and tetrakis(triphenylphosphine)palladium (0.04 g, 0.038 mmol) was added. The mixture was heated to 110 °C, refluxed, and reacted overnight. After confirming complete reaction by TLC, the reaction mixture was cooled to room temperature, washed with water, and extracted with dichloromethane. The resulting organic phase was dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The solution was purified by silica gel column chromatography using dichloromethane / ethyl acetate (3:1, V / V) as the eluent to give a syrupy liquid 3b (0.35 g, 86%).

[0197] (3) Synthesis of the compound shown in formula (I9) (abbreviated as BICz-PhPA):

[0198] .

[0199] Compound 2b (0.35 g, 0.66 mmol) was dissolved in anhydrous 1,4-dioxane (10 mL) under a nitrogen atmosphere, and trimethylbromosilane (1.02 g, 6.66 mmol) was added dropwise. After reacting at room temperature for 24 h, 5 mL of methanol was added and stirring continued for 3 h. Partial solvent was removed by rotary evaporation, followed by the addition of 5 mL of methanol, and then distilled water was added dropwise until the solution became opaque. The mixture was stirred overnight. The product was filtered off, washed with water, and dried to give a white solid BICz-PhPA (0.23 g, 73%). Mass spectrometry (m / z): 490.15 [M+H] + .

[0200] Application Example 1:

[0201] The phosphate-anchored methoxy asymmetric compound prepared in Example 1 above was used as a self-assembled hole transport material in a perovskite solar cell. The perovskite solar cell includes a substrate, a hole transport layer, a perovskite light absorption layer, an electron transport layer and an electrode layer stacked sequentially.

[0202] Indium tin oxide (ITO) transparent conductive film with a thickness of 300 nm and a sheet resistance of 20 Ω / sq was deposited on a glass substrate using atmospheric pressure chemical vapor deposition (APCVD). The film was cut into 2 cm × 2 cm cubes. The ITO glass substrate was then sequentially cleaned with glass cleaning solution, deionized water, acetone, and isopropanol for 15 min each, and then dried with compressed air. The cleaned ITO glass was then treated with ultraviolet ozone for 15 min to improve wettability.

[0203] A hole transport layer was prepared on a transparent conductive film. An anhydrous ethanol solution of the compound from Example 1 was prepared to a concentration of 0.5 mg / mL. The solution was then spin-coated on an ITO substrate at 3000 rpm for 30 s to form a hole transport layer with a thickness of 1 nm.

[0204] A perovskite light-absorbing layer was prepared by spin-coating onto a hole transport layer substrate. (Following Cs...) 0.05 FA 0.8 MA 0.15 Pb(I) 0.76 Br 0.24 A perovskite precursor solution was prepared at a ratio of 3:1. After filtration through a polytetrafluoroethylene (PTFE) membrane with a pore size of 0.22 µm, a perovskite film was deposited in a glove box using ethyl acetate as the antisolvent. The thickness of the perovskite light-absorbing layer was approximately 1 μm.

[0205] In high vacuum (less than 10) -5 Under the conditions of Pa), a 26 nm thick C60 layer and a 6 nm thick BCP layer were sequentially deposited as electron transport layers by thermal evaporation.

[0206] Use 0.12cm 2 A silver electrode with a thickness of 100 nm was deposited on the electron transport layer using a metal mask. The perovskite solar cell of this application example was tested and its power conversion efficiency was found to be 21.97%.

[0207] Application Example 2:

[0208] The specific preparation process of Application Example 2 is largely the same as that of Application Example 1, except that the compound used in the hole transport layer is the compound of Example 2. The perovskite solar cell of this application example was tested and its energy conversion efficiency was 22.11%.

[0209] Application Example 3:

[0210] The specific preparation process of Application Example 3 is largely the same as that of Application Example 1, except that the concentration of the ethanol solution used to prepare the hole transport layer material is 0.2 mg / mL. The perovskite solar cell of this application example was tested and its energy conversion efficiency was found to be 22.99%.

[0211] Application Example 4:

[0212] The specific preparation process of Application Example 4 is largely the same as that of Application Example 2, except that the concentration of the ethanol solution used to prepare the hole transport layer material is 0.2 mg / mL. The perovskite solar cell of this application example was tested and its photoelectric conversion efficiency was found to be 22.95%.

[0213] Comparative application example 1:

[0214] The specific preparation process of Comparative Application Example 1 is largely the same as that of Application Example 3, except that the compound used in the hole transport layer is the compound shown in Formula A below:

[0215] Formula A was used to test the perovskite solar cell in this comparative application example, and its power conversion efficiency was found to be 20.29%.

[0216] Compare with application example 2:

[0217] The specific preparation process of Comparative Application Example 2 is largely the same as that of Application Example 3, except that the compound used in the hole transport layer is the compound shown in Formula B below:

[0218] Formula B was used to test the perovskite solar cell in this comparative application example, and its power conversion efficiency was found to be 20.21%.

[0219] IV tests were then conducted on the perovskite solar cells obtained in Case 3 and Comparative Application Example 1, and the results are shown in Table 1 below.

[0220] Table 1

[0221]

[0222] Figure 2 The external quantum efficiency and current density curves of the perovskite solar cells in Application Example 3 and Comparative Application Example 1 of this application are shown. Figure 2 As shown, Application Example 3 exhibits a high EQE value across the 350-750 nm wavelength range, with the EQE reaching its peak in the 400-500 nm band, representing a 5% improvement compared to Comparative Application Example 1. This demonstrates that the present invention effectively improves photoelectric conversion efficiency by introducing an asymmetric structure of benzo[a]indene-carbazole groups as a hole transport layer.

[0223] Figure 3 The current density-voltage curves of the perovskite solar cells in Application Example 3 and Comparative Application Example 1 of this application are shown. Figures 2-3 As shown in Table 1, the hole transport layer in Application Example 3, which uses an asymmetric structure with a benzo[a]indo[a]carbazole group, exhibits higher energy conversion efficiency, open-circuit voltage, fill factor, and short-circuit current compared to Comparative Application Example 1. This is because the introduction of the aforementioned specific group utilizes a delocalized large π-conjugated system formed by polycyclic aromatic fused rings, increasing molecular rigidity. This allows for increased density during self-assembly, reducing lead vacancies and other defects, thus achieving better energy level matching with the perovskite light absorption layer. This is beneficial for hole transport and thereby improves photoelectric conversion efficiency.

[0224] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hole transport layer material, comprising a compound with the structure shown in formula (I): Equation (I); R1, R2, R3, and R4 represent monosubstituted to the most permissible substituents, each independently selected from hydrogen, halogen, cyano, nitro, hydroxyl, substituted or unsubstituted C1 to C4. 30 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C1-C 30 Silyl, substituted or unsubstituted C1~C 30 Alkylthio; R5 and R6 are each independently selected from halogenated, substituted, or unsubstituted C1-C6 groups. 30 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 30 Alkoxy, substituted or unsubstituted C1-C 30 Silyl, substituted or unsubstituted C1~C 30 Alkylthio, substituted or unsubstituted C6~C 30 Aryl; L1 is substituted or unsubstituted C6~C 30 aryl, substituted or unsubstituted C3~C 30 Heteroaryl, substituted or unsubstituted C1~C 30 Alkylene, substituted or unsubstituted C1~C 30 alkeneoxy, substituted or unsubstituted C1~C 30 Any one of the alkylthio groups; In cases where the substituted or unsubstituted groups have substituents, the substituents are selected from halogens, hydroxyl groups, nitro groups, amino groups, and C1-C6 groups. 12 Alkyl, C3~C 12 cycloalkyl, C1~C 12 Alkoxy, C1~C 12 One or a combination of at least two of the alkylthio groups.

2. The hole transport layer material according to claim 1, wherein, No two adjacent groups in R1, R2, R3, R4, R5, and R6 can form a ring.

3. The hole transport layer material according to claim 1, wherein, R1, R2, R3, and R4 are each independently selected from hydrogen, C1~C1. 12 Alkyl, C1~C 12 Alkoxy, C1~C 12 Any of the alkylthio groups, where R5 and R6 are each independently selected from C1 to C6. 12 Alkyl, substituted or unsubstituted C6~C 30 In the case of an aryl group, where the substituted or unsubstituted group has a substituent, the substituent is selected from C1 to C2. 12 alkyl; L1 is C1~C 12 Alkylene, C1~C 12 alkeneoxy group, C1~C 12 alkylthionyl, C6~C 30 One of the aryl groups.

4. The hole transport layer material according to claim 1, wherein, R1, R2, R3, and R4 are each independently selected from hydrogen, halogen, methyl, ethyl, isopropyl, and tert-butyl; R5 and R6 are each independently selected from any one of methyl, ethyl, isopropyl, and tert-butyl. L1 is C1~C 12 Alkylene or substituted or unsubstituted C6~C 30 Alpha-aryl; In cases where the substituted or unsubstituted groups have substituents, the substituents are selected from C1 to C2. 12 alkyl.

5. The hole transport layer material according to claim 1, wherein, R1, R2, R3, and R4 are all hydrogen atoms, while R5 and R6 are both methyl atoms.

6. The hole transport layer material according to claim 5, wherein, L1 is C1~C 12 Straight-chain alkylene or phenylene.

7. The hole transport layer material according to claim 1, wherein, The hole transport layer material has the following formula (I1) ~ (I 23 Compounds with the structure shown in the diagram: Formula (I1) Equation (I2), Equation (I3) Equation (I4) Formula (I5) Equation (I6) Equation (I7) Formula (I8) Formula (I9) Formula (I 10 ), Equation (I 11 ), Equation (I 12 ), Formula (I 13 ), Formula (I 14 ), Equation (I 15 ), Equation (I 16 ), Equation (I 17 ), Equation (I 18 ), Equation (I 19 ), Equation (I 20 ), Equation (I 21 ), Equation (I 22 ), Equation (I 23 ).

8. A solar cell, comprising a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode layer sequentially stacked, wherein, The hole transport layer comprises the hole transport layer material as described in any one of claims 1 to 7.

9. The solar cell according to claim 8, wherein, The perovskite light-absorbing layer comprises perovskite material ABX3, wherein A includes one or more of cesium ions, rubidium ions, potassium ions, methylamine ions, formamidinium ions, methylenediamine ions, benzylamidinium cations, and guanidine cations; B includes one or more of lead ions and tin ions; and X includes one or more of chloride ions, bromide ions, and iodide ions.

10. The solar cell according to claim 8, wherein, The substrate is a crystalline silicon battery. Preferably, the bandgap width of the solar cell is 1.6~1.8 eV.

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