Indole compound and solar cell

Abstract

The invention provides an indole compound and a solar cell. The indole compound has a structural formula as shown in a formula (I). At least one of R1-R7 has a structure as shown in a formula (Hy1): L1 is any one of substituted or unsubstituted C6-C30 arylene, substituted or unsubstituted C3-C30 heteroarylene, substituted or unsubstituted C1-C30 alkylene, substituted or unsubstituted C1-C30 alkyleneoxy and substituted or unsubstituted C1-C30 alkylenesulfenyl, and R8 is any one of a phosphate group, a carboxylic acid group and a sulfonic acid group; when R1-R7 do not represent the structure represented by formula (Hy1), R1-R7 represent the structure represented by formula (Hy1); a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C1-C30 alkylthio group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30 arylamino group, a substituted or unsubstituted C3-C30 heteroaryl group, a substituted or unsubstituted C3-C30 heteroarylamino group, a substituted or unsubstituted C3-, each independently selected from hydrogen, halogen, nitro, hydroxyl, substituted or unsubstituted C1-C30 alkyl group, substituted or unsubstituted C1-C30 alkoxy group, substituted or unsubstituted C1-C30 alkylthio group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C3-C30 heteroarylamino group, substituted or unsubstituted C3- and C12 cycloalkyl is selected from any one of C12 cycloalkyl.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more specifically, to an indole compound and a solar cell. Background Technology

[0002] Perovskite solar cells possess advantages such as high photoelectric conversion efficiency and low-cost solution processing potential, with their photoelectric conversion efficiency increasingly approaching that of crystalline silicon cells, indicating significant application potential. However, perovskite solar cells still suffer from poor stability and difficulties in large-area fabrication, hindering their widespread application compared to crystalline silicon cells.

[0003] 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. However, in related technologies, the hole transport layer material often uses a carbazole ring framework as the core building block, which suffers from problems such as low intrinsic conductivity, insufficient stability, and poor energy level matching. Summary of the Invention

[0004] In view of this, in order to at least partially solve the aforementioned technical problems, this application provides an indole compound and a solar cell.

[0005] According to one embodiment of this application, an indole compound is provided having the structural formula shown in formula (I):

[0006] Formula (I);

[0007] Wherein, at least one of R1, R2, R3, R4, R5, R6, and R7 has the following formula (Hy 1 The structure shown is as follows:

[0008] Hy 1 );

[0009] Where * indicates a connection site; L1 represents 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 R8 is selected from any of the alkylthionyl groups, and R1, R2, R3, R4, R5, R6, and R7 are not of the formula (Hy). 1 In the case of the structure shown, each group is independently selected from hydrogen, halogen, nitro, hydroxyl, substituted or unsubstituted C1~C.30 Alkyl, substituted or unsubstituted C1~C 30 Alkoxy, substituted or unsubstituted C1~C 30 Alkylthio, substituted or unsubstituted C6~C 30 aryl, substituted or unsubstituted C6~C 30 arylamino, substituted or unsubstituted C3~C 30 heteroaryl, substituted or unsubstituted C3~C 30 heteroarylamino, substituted or unsubstituted C3~C 12 Any one of the cycloalkyl groups; where the above-mentioned 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 Alkylthio, C6~C 30 Aryl, C3~C 30 One or at least two of the heteroaryl groups.

[0010] 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 an indole compound as described above.

[0011] According to the indole compounds provided in the embodiments of this application, the higher intrinsic electron density of the indole ring results in a deeper highest occupied molecular orbital (HOMO) level compared to the carbazole ring in related technologies. This provides a wider controllable space for energy level adjustment, enabling better energy level matching with the perovskite valence band top (e.g., -5.4 eV) in the perovskite light-absorbing layer, thereby improving the open-circuit voltage of the resulting solar cell. The indole main ring of this application provides multiple modifiable sites. Utilizing the asymmetric structure of indole, specific and highly directional face-to-face π-π bond stacking of indole compounds is induced in the hole transport layer, providing higher hole mobility. By introducing electron-donating and weakly electron-withdrawing groups at different sites of the indole compounds, synergistic fine-tuning of the HOMO and lowest unoccupied molecular orbitals (LUMO) is achieved, resulting in better energy level matching with the perovskite layer and improving the cell performance of the solar cell. In addition, indole compounds are widely available, low in cost, and have broad application prospects. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments.

[0013] In the following detailed description, numerous specific details are set forth for ease of explanation to provide a thorough understanding of the embodiments of this application. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0014] 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.

[0015] When using expressions such as "at least one of A, B and 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 and 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.).

[0016] Related technologies often utilize hole transport layer materials with a carbazole ring framework. However, the modification sites for carbazole are relatively fixed. Strong electron-donating groups are typically introduced to modulate the HOMO level, but these groups create a significant energy level shift between the introduced strong electron-donating groups and the valence band top of the perovskite, leading to open-circuit voltage loss. Furthermore, symmetry modification of the carbazole ring framework often results in excessive or insufficient energy level changes, limiting the matching with perovskite energy levels.

[0017] In realizing the concept of this application, it was discovered that by introducing compounds with an indole main ring structure into the hole transport layer material, the hole mobility can be improved by utilizing the conjugated structure and electron-rich properties of the indole ring itself. Adjusting the R1 to R7 groups of the indole compounds helps to further expand the conjugated structure, optimize the orbital energy levels of the indole molecules, achieve good energy level matching between the indole and perovskite active layers and electrodes, and thus efficiently extract and transport holes.

[0018] Specifically, according to one aspect of this application, an indole compound is provided having a structural formula as shown in formula (I):

[0019] Formula (I).

[0020] Wherein, at least one of R1, R2, R3, R4, R5, R6, and R7 has the following formula (Hy 1 The structure shown is as follows:

[0021] Hy 1 );

[0022] Where * indicates a connection site; L1 represents 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 R8 is selected from any of the alkylthionyl groups, and R1, R2, R3, R4, R5, R6, and R7 are not of the formula (Hy). 1 In the case of the structure shown, each group is independently selected from hydrogen, halogen, nitro, hydroxyl, substituted or unsubstituted C1~C. 30 Alkyl, substituted or unsubstituted C1~C 30 Alkoxy, substituted or unsubstituted C1~C 30 Alkylthio, substituted or unsubstituted C6~C 30 aryl, substituted or unsubstituted C6~C 30 arylamino, substituted or unsubstituted C3~C 30 heteroaryl, substituted or unsubstituted C3~C 30 heteroarylamino, substituted or unsubstituted C3~C 12 Any one of the cycloalkyl groups; where the above-mentioned 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 Alkylthio, C6~C 30 Aryl, C3~C 30 One or a combination of at least two of the following: heteroaryl, phosphoric acid, carboxylic acid, and sulfonic acid groups.

[0023] According to embodiments of this application, by utilizing the favorable conjugated structure and electron-rich properties of the indole ring, a high hole mobility can be achieved. Introducing other substituents onto the side chain of the indole ring further optimizes the orbital energy levels of indole compounds, achieving good energy level matching with the perovskite active layer, thereby efficiently extracting and transporting holes. Introducing the above formula (Hy...) into the indole compound molecule... 1 The R8 group in the above formula (Hy) acts as a strongly polar anchoring group, capable of forming strong coordination bonds or hydrogen bonds with the perovskite active layer or substrate. This effectively passivates defects on the perovskite surface, suppresses non-radiative recombination, reduces carrier loss, and improves the open-circuit voltage and fill factor of the solar cell. Furthermore, the above formula (Hy) 1The linking group L1 in the indole compound can regulate the stacking and van der Waals forces between indole molecules, ensuring good charge transport channels and preventing phase separation caused by excessive aggregation.

[0024] In this application, at least one of the above-mentioned "R1, R2, R3, R4, R5, R6, R7" has the following formula (Hy 1 The structure shown can be understood as any one of R1 to R7 having the formula (Hy). 1 The structure shown in the diagram can also be one of multiple structures from R1 to R7 that have the formula (Hy). 1 The structure shown in ) can be multiple, for example, two or three. Multiple structures in R1~R7 have the formula (Hy 1 In the case of the structure shown, the multiple structures can be the same or different, but are preferably the same.

[0025] 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.

[0026] 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.

[0027] In this specification, "each independently" means that when there are multiple subjects, they may be the same or different from each other.

[0028] 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.

[0029] 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.

[0030] Examples of halogens in this specification include fluorine, chlorine, bromine, and iodine.

[0031] 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.

[0032] 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, the biphenyl group is selected from 2-biphenyl, 3-biphenyl, and 4-biphenyl; the terphenyl group 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; the naphthyl group includes 1-naphthyl or 2-naphthyl; the anthracene group is selected from 1-anthrayl, 2-anthrayl, and 9-anthrayl; the fluorenyl group is selected from 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl, and 9-fluorenyl; the pyrene group is selected from 1-pyrene, 2-pyrene, and 4-pyrene; and the tetraphenyl group is selected from 1-tetraphenyl, 2-tetraphenyl, and 9-tetraphenyl. C6~C 30 aryl and C6~C 30 The same applies to aryl groups; simply replace the aforementioned groups with the corresponding subunits.

[0033] In this specification, the term "heteroaryl" includes the concepts of monocyclic heteroaryl and fused-ring heteroaryl. Monocyclic heteroaryl refers to a molecule containing at least one heteroaryl group. When a molecule contains one heteroaryl group and other groups (such as aryl, heteroaryl, alkyl, etc.), the heteroaryl group and the other groups are independent of each other and connected by a single bond, exemplarily such as pyridine, furan, thiophene, etc. Fused-ring heteroaryl refers to a molecule formed by the fusion of at least one phenyl group and at least one heteroaryl group, or by the fusion of at least two heteroaryl rings, exemplarily such as quinoline, isoquinoline, benzofuran, dibenzofuran, benzothiophene, dibenzothiophene, etc.

[0034] 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.

[0035] 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.

[0036] C6~C mentioned in this application 30 Examples of aryl amino groups include phenylamino, methylphenylamino, naphthylamino, anthraceneylamino, phenanthreneamino, and biphenylamino.

[0037] C3~C mentioned in this application 30 Examples of heteroaryl amino groups include pyridinylamino, pyrimidinylamino, and dibenzofuranylamino.

[0038] 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.

[0039] Furthermore, one or more of R1, R2, R3, R4, R5, R6, and R7 are C1~C 30 In the case of alkyl groups, the C1-C 30 Alkyl groups are preferably methyl and ethyl.

[0040] In L1, C1~C 30 In the case of alkylene groups, the C1-C 30 The alkylene group is preferably n-propylene.

[0041] In this specification, C1~C 30Examples 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.

[0042] In this specification, C1~C 30 Examples of alkoxy groups can be found above, where the oxygen is replaced by sulfur.

[0043] 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.

[0044] In this specification, C3~C 12 Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0045] In some embodiments, any two adjacent groups among R1, R2, R3, R4, R5, R6, and R7 do not fuse into a ring. If adjacent groups fuse to form additional aromatic or heteroaromatic rings, it will expand the conjugated system of the indole compound molecule, resulting in a significant decrease in the HOMO energy level. This causes energy level mismatch between the hole transport layer and the perovskite active layer, hindering the effective extraction and transport of holes and reducing the performance of the solar cell.

[0046] In some implementations, R1, R2, R3, R4, R5, R6, and R7 are each independently selected from C1 to C2. 12 Alkyl, C1~C 12 Alkoxy, C1~C 12 Any of the alkylthio groups; L1 is C1~C 12 Alkylene, C1~C 12 alkeneoxy group, C1~C 12 Alkylthioyl groups. This configuration, utilizing the substituents in R1-R7 to introduce electron-donating and weakly electron-withdrawing groups, allows for appropriate fine-tuning of the HOMO and LUMO energy levels of the indole backbone. This facilitates energy level matching with the perovskite active layer, improving the open-circuit voltage and fill factor of the solar cell. The flexible segments such as alkyl, alkoxy, and alkylthioyl groups in the linking group L1 help disrupt the strong π-π stacking between indole molecules, significantly improving the solubility of these indole compounds in common organic solvents. This makes them more suitable for conventional solution processing techniques, such as spin coating and blade coating, thereby improving the film quality of the hole transport layer.

[0047] In some embodiments, R1, R2, R3, R4, R5, R6, and R7 are each independently selected from hydrogen, halogen, methyl, ethyl, isopropyl, tert-butyl, substituted or unsubstituted naphthyl, substituted or unsubstituted phenanthryl, substituted or unsubstituted anthracene, C6~C 30 Arylamino, substituted or unsubstituted phenyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophene, substituted or unsubstituted fluoreneyl; L1 is C1~C 12 A straight-chain alkylene group; where the substituted or unsubstituted group has a substituent, the substituent is selected from one or a combination of at least two of methoxy, methyl, ethyl, isopropyl, tert-butyl, methylthio, phenyl, and carbazole. This configuration results in better energy level matching between the hole transport layer and the perovskite active layer, thereby improving the cell performance of the solar cell and further increasing the energy conversion efficiency.

[0048] Preferably, any one of R1, R2, R3, R4, R5, R6, and R7 has the formula (Hy 1 The structure shown is as follows.

[0049] In some further preferred embodiments, any one of R2, R3, R4, R5, R6, and R7 has the formula (Hy 1 The structure shown in the diagram; in R2, R3, R4, R5, R6, and R7, it is not the formula (Hy). 1 In the case of the structure shown, each element is independently selected from hydrogen, halogen, C1~C2. 12 Alkyl, C6~C 30 Any of the aryl groups; R1 is C1~C 12 Alkyl group. This configuration, by attaching an alkyl group at the pyrrole nitrogen, results in one of the other substituent positions having the formula (Hy... 1 The structure shown helps to improve the energy level matching between the hole transport layer and the perovskite light absorption layer while maintaining good solubility, thereby improving the film quality of the hole transport layer.

[0050] In some preferred embodiments, L1 is a straight chain C1~C 12 Alkylene group, R8 is a phosphate group. This configuration further enhances the performance of the resulting solar cell.

[0051] In some specific embodiments, indole compounds have the following formulas (I1) to (I2). 70 The structure shown is as follows:

[0052] Equation (I1); Equation (I2); Equation (I3);

[0053] Equation (I4); Equation (I5); Equation (I6);

[0054] Equation (I7); Equation (I8); Equation (I9);

[0055] Formula (I 10 ); Formula (I 11 );

[0056] Formula (I 12 ); Formula (I 13 ); Formula (I 14 );

[0057] Formula (I 15 ); Formula (I 16 ); Formula (I 17 );

[0058] Formula (I 18 ); Formula (I 19 ); Formula (I 20 );

[0059] Formula (I 21 ); Formula (I 22 ); Formula (I 23 );

[0060] Formula (I 24 ); Formula (I 25 ); Formula (I 26 );

[0061] Formula (I 27 ); Formula (I 28 );

[0062] Formula (I 29 ); Formula (I30 );

[0063] Equation (I 31 ); Equation (I 32 ); Equation (I 33 );

[0064] Equation (I 34 ); Equation (I 35 ); Equation (I 36 );

[0065] Equation (I 37 ); Equation (I 38 ); Equation (I 39 );

[0066] Equation (I 40 ); Equation (I 41 );

[0067] Equation (I 42 ); Equation (I 43 );

[0068] Equation (I 44 ); Equation (I 45 );

[0069] Equation (I 46 ); Equation (I 47 );

[0070] Equation (I 48 ); Equation (I 49 );

[0071] Equation (I 50 ); Equation (I 51 );

[0072] Equation (I 52 ); Equation (I 53 );

[0073] Formula (I 54 ); Formula (I 55 );

[0074] Formula (I 56 ); Formula (I 57 );

[0075] Formula (I 58 ); Formula (I 59 );

[0076] Formula (I 60 ); Formula (I 61 );

[0077] Formula (I 62 ); Formula (I 63 );

[0078] Formula (I 64 ); Formula (I 65 ); Formula (I 66 );

[0079] Formula (I 67 ); Formula (I 68 );

[0080] Formula (I 69 ), Formula (I 70 This configuration, when using the aforementioned indole compounds as a hole transport layer, helps to simultaneously optimize their solubility, orbital energy levels, carrier transport performance, and interfacial bonding ability, resulting in perovskite solar cells with better cell performance.

[0081] According to another aspect of this application, an indole compound is provided, which has the following formula (I 71 The structure shown is as follows:

[0082] Formula (I 71 ).

[0083] According to embodiments of this application, the indole compounds described above, when used as a hole transport layer, help improve the performance of solar cells.

[0084] It is understood that the above-mentioned indole compounds can be prepared by common preparation methods in the field. Moreover, the preparation methods of the above-mentioned indole compounds are simple, the intermediates in the preparation process are widely available and low in cost, and the synthesis routes are flexible and diverse, providing a variety of possibilities for realizing high-performance and low-cost hole transport materials, and have significant application prospects.

[0085] Specifically, taking the structure shown in formula (I1) as an example, this application schematically illustrates the preparation process of the above-mentioned indole compounds. It can be understood that 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-mentioned materials.

[0086] Under the protection of inert gas, The solution is prepared by substitution reaction of 1,3-dibromopropane with potassium carbonate in an organic solvent. .

[0087] Its preparation process can be as follows:

[0088] .

[0089] Under the protection of inert gas, The product was prepared by reacting it with triethyl phosphite under heating. .

[0090] Its preparation process can be as follows:

[0091] .

[0092] Under the protection of inert gas, The indole compound with the structure shown in formula (I1) was prepared by reacting it with trimethylbromosilane in 1,4-dioxane.

[0093] Its preparation process can be described as follows:

[0094] .

[0095] According to another embodiment of the present invention, 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 an indole compound as described above.

[0096] According to embodiments of the present invention, an indole structure is used as the main framework, which has excellent hole transport capability. An anchoring group connected by a linking group is used in at least one of the substituents, which helps to optimize the energy level structure of the above-mentioned indole compounds, achieve good energy level matching with perovskite materials, improve hole extraction and transport performance, and thus improve the energy conversion efficiency of solar cells.

[0097] In some preferred embodiments, any one of R2, R3, R4, R5, R6, and R7 has the formula (Hy 1 The structure shown is given, and R1 is C1~C 12 Alkyl groups can improve energy level matching while enhancing wettability with perovskite materials and improving the uniformity of hole transport layer formation, thus facilitating the fabrication of large-area perovskite solar cells.

[0098] According to embodiments of this application, the hole transport layer can be prepared by spin coating, and its thickness can be 10~30nm.

[0099] According to an embodiment of this application, the perovskite light-absorbing layer comprises perovskite material ABX3, wherein A comprises one or more of cesium ions, rubidium ions, potassium ions, methylamine ions, formamidinium ions, methylenediamine ions, benzylamidinium cations, and guanidine cations; B comprises one or more of lead ions, copper ions, zinc ions, gallium ions, tin ions, and calcium ions; and X comprises one or more of fluoride ions, chloride ions, bromide ions, iodide ions, thiocyanate ions, tetrafluoroborate ions, hexafluorophosphate ions, formate ions, and acetate ions.

[0100] 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, can significantly improve wettability on the substrate surface, resulting in a more uniform spread of the perovskite precursor solution. Consequently, the perovskite light-absorbing layer film formed by self-assembly on the substrate is more uniform and dense, less prone to aggregation, and exhibits strong stability when subjected to solvent washing or thermal stress.

[0101] In some embodiments, the electron transport layer material includes one or more of fullerenes and fullerene derivatives, including 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 PCBM. For example, a C60 electron transport layer can be prepared by thermal evaporation deposition, with a thickness of 15-20 nm. A tin oxide electron transport layer can be prepared by atomic layer deposition (ALD) technology, with a thickness of 15-20 nm.

[0102] In some embodiments, the hole transport layer and electron transport layer 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 in the art, they will not be listed here.

[0103] According to embodiments of this application, the electrode layer may be, for example, one of indium zinc oxide (IZO), indium tin oxide (ITO), or aluminum-doped zinc oxide (AZO).

[0104] In some embodiments, the substrate is a crystalline silicon bottom cell. Thus, the 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 it can be a thin-film polycrystalline silicon cell; this application does not impose any limitations.

[0105] According to embodiments of this application, since the hole transport layer in the perovskite top cell uses an indole compound with the aforementioned structure, the mutual compatibility of the indole compound structure allows for better energy level matching between the perovskite light absorption layer and the electrode layer, which helps to improve the cell performance, such as open-circuit voltage, of the tandem solar cell composed of a crystalline silicon bottom cell and a perovskite top cell.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] The present application is further illustrated below through embodiments 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.

[0112] 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.

[0113] Synthesis of Example 1 (i.e., the compound shown in formula (I1)):

[0114] Synthesis of intermediate M1-1

[0115] .

[0116] Under nitrogen protection, starting material P1-1 (10 g, 0.068 mol), 1,3-dibromopropane (50 g, 0.247 mol), potassium carbonate (46 g, 0.340 mol), and acetonitrile (80 mL) were placed in separate 250 mL three-necked round-bottom flasks and refluxed for 12 h before the reaction was stopped. After the reaction solution cooled to room temperature, it was extracted with ethyl acetate and water, and the organic phase was collected. After dehydration with anhydrous magnesium sulfate, the organic phase was concentrated by vacuum distillation. The product M1-1 was purified by column chromatography using ethyl acetate:petroleum ether (volume ratio 1:50) as the eluent. The post-column solution was concentrated to obtain 2.5 g of product M1-1, with a yield of 69.4%.

[0117] Synthesis of intermediate M1-2

[0118] .

[0119] Under nitrogen protection, intermediate M1-1 (12.5 g, 0.047 mol) and triethyl phosphite (75 mL, 0.376 mol) were placed in separate 250 mL three-necked round-bottom flasks, and the reaction was refluxed for 24 h to terminate the reaction. After the reaction was cooled to room temperature, the solvent was removed by vacuum distillation, and the product was purified by column chromatography using ethyl acetate:petroleum ether (volume ratio 1:3) as the eluent. The post-column solution was concentrated to obtain 11.8 g of solid product M1-2, with a yield of 78%.

[0120] Synthesis of the compound shown in formula (I1)

[0121] .

[0122] Under nitrogen protection, 11.8 g (0.036 mol) of M1-2 and 1,4-dioxane (80 mL) were placed in a three-necked round-bottom flask and stirred thoroughly. Trimethylbromosilane (5.5 g, 0.36 mol) was slowly added dropwise to the flask, and the reaction was carried out at room temperature for 24 h. After the reaction was complete, 80 mL of deionized water was added to the reaction solution, and the mixture was stirred overnight. A large amount of solid precipitated out. After filtration, the mass of solid product compound 1 was 4.2 g, with a yield of 43%. Mass spectrometry analysis showed (m / z): 268.10 [M+H] + The specific structure of the compound shown in formula (I1) was confirmed.

[0123] Examples 2 to 4:

[0124] The compounds shown in the table below were prepared according to the synthetic method of the compound in Example 1 (where Example 2 is the compound shown in formula (I7), and Example 3 is the compound shown in formula (I)). 17 The compound shown in Example 4 is of formula (I) 28The compounds shown in the table are different in that different PX-1 is used instead of P1-1, different MX-1 is used instead of M1-1, and different MX-2 is used instead of M1-2. The main raw materials used, the synthesized compounds, their yields and mass spectra are shown in Table 1 below.

[0125] Table 1

[0126]

[0127] Example 5 (i.e., formula (I) 40 Synthesis of the compound shown in the figure:

[0128] Synthesis of intermediate M40-1

[0129] .

[0130] Under nitrogen protection, 10 g (0.037 mol) of raw material P40-1, 0.237 g of tetrabutylammonium bromide, 2.16 g (0.054 mol) of potassium hydroxide aqueous solution, and acetonitrile were placed in a three-necked round-bottom flask and heated to 50 °C. After stirring for 1 hour, 6.3 g (0.0407 mol) of iodoethane was added, and the reaction was allowed to proceed for 24 hours. After the reaction was complete, the mixture was extracted with ethyl acetate and water. The organic phase was washed with water until neutral, dried over anhydrous magnesium sulfate, and purified by column chromatography using ethyl acetate:petroleum ether (volume ratio 1:5) as the eluent. The product M40-1 was obtained in a mass of 7 g, with a yield of 63%.

[0131] Synthesis of intermediate M40-2

[0132] .

[0133] Under nitrogen protection, M40-1 (7 g, 0.023 mol) and THF (56 mL) were added separately to round-bottom flasks. After stirring at -78 °C for 10 minutes, n-butyllithium (0.53 mL) was added dropwise to the solution. The reaction was continued at -78 °C for 1 hour. Then, 1,3-dibromopropane (12 g, 0.06 mol) was added dropwise to the reaction solution. The reaction was stopped after 2 hours. The reaction solution was extracted with sulfuric acid aqueous solution and dichloromethane until neutral, then dehydrated with anhydrous magnesium sulfate, filtered, and distilled under reduced pressure. The product was purified by column chromatography using ethyl acetate:petroleum ether (volume ratio 1:5) to obtain product M40-2 with a mass of 6 g, yielding 77.1%.

[0134] Formula (I 40 Synthesis of the compound shown in the figure

[0135] ;

[0136] .

[0137] The formula (I) was prepared according to the synthesis method of Example 1. 40 The compound shown was obtained in 75.3% by mass spectrometry analysis (m / z): 354.13 [M+H]. + This confirms equation (I) 40 The specific structure of the compound shown is shown in the figure.

[0138] Example 6 (i.e., formula (I) 59 Synthesis of the compound shown in the figure:

[0139] The compounds shown in Table 2 below were prepared according to the synthetic method of the compounds in Example 5, except that P59-1 was used instead of M40-1, M59-1 was used instead of M40-2, and M59-2 was used instead of M40-3. The main raw materials used, the synthesized compounds, their yields and mass spectra are shown in Table 2 below.

[0140] Table 2

[0141]

[0142] Example 7

[0143] The compounds shown in the table below were prepared according to the synthetic method of the compound in Example 1 (where Example 2 is the compound shown in formula (I7), and Example 3 is the compound shown in formula (I)). 17 The compound shown in Example 4 is of formula (I) 28 The compound shown in Example 7 is of formula (I) 70 The compounds shown in the figure are different in that different PX-1 is used instead of P1-1, different MX-1 is used instead of M1-1, and different MX-2 is used instead of M1-2. The main raw materials used, the synthesized compounds, their yields and mass spectra are shown in Table 3 below.

[0144] Table 3

[0145]

[0146] Application Example 1:

[0147] The compound prepared in Example 1 was used as a hole transport material in perovskite solar cells.

[0148] An 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 and cleaned with anhydrous ethanol.

[0149] A hole transport layer was prepared on a transparent conductive film. A toluene solution of the compound from Example 1 was prepared at a concentration of 10 mg / mL and sonicated for 15 min. The toluene solution of the compound from Example 1 was spin-coated onto a substrate with a transparent conductive film at a spin speed of 1500 rpm for 15 s. The thickness of the formed hole transport layer was 20 nm.

[0150] A perovskite layer was prepared on a hole transport layer substrate using a two-step spin-coating method. A lead iodide solution (1.5 M, DMSO:DMF = 9:1) was prepared and spin-coated to obtain a precursor layer. The precursor layer was heated at 70°C for 1 min on a hot stage, and after cooling, a solution of FAI / MABr / MACl in isopropanol (FAI:MABr:MACl = 9:1:1, 60 mg / mL) was spin-coated. Immediately after spin-coating, the substrate was heated at 150°C for 20 min. The perovskite layer thickness was approximately 500 nm.

[0151] Particles were spin-coated onto the perovskite layer as an electron transport layer with a thickness of 10 nm.

[0152] A silver electrode with a thickness of 100 nm was prepared by vapor deposition on the electron transport layer.

[0153] Application Examples 2 to 7:

[0154] The specific preparation process of Application Examples 2 to 7 is largely the same as that of Application Example 1, except that the compounds used in the hole transport layer are (the compounds used in Examples 2 to 7).

[0155] Comparative application example 1:

[0156] The specific preparation process of Comparative Application Example 1 is largely the same as that of Application Example 1, except that the compound used in the hole transport layer is the compound shown in Formula A below:

[0157] Formula A.

[0158] Compare with application example 2:

[0159] The specific preparation process of Comparative 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 shown in Formula B below:

[0160] Formula B.

[0161] Compare with example 3:

[0162] The specific preparation process of Comparative Application Example 3 is largely the same as that of Application Example 1, except that the compound used in the hole transport layer is the compound shown in Formula C below:

[0163] Formula C.

[0164] The perovskite solar cells obtained from Application Examples 1 to 7 and Comparative Application Examples 1 to 3 were further subjected to IV tests, and the results are shown in Table 4 below.

[0165] Table 4

[0166]

[0167] Comparing the test results of Application Examples 1-7 with those of Comparative Application Examples 1-3, it can be seen that the hole transport layer in the application examples, using a structure with a specific indole group, exhibits higher energy conversion efficiency, open-circuit voltage, and fill factor compared to the comparative application examples. This is because the introduction of the indole group and its coordination with other substituents broadens the HOMO energy level, making it more compatible with the perovskite light absorption layer, which facilitates charge transport and thus improves the performance of the solar cell. Furthermore, comparing Application Examples 1 and 7 shows that using an alkylene group as the linking group connected to the phosphate group results in relatively better cell performance compared to phenylene groups. It should be noted that Application Examples 5 and 6, based on the use of phosphate anchoring groups with alkyl links at substituent positions other than the pyrrole nitrogen, provide better matching effects compared to other application examples, thus exhibiting higher cell performance.

[0168] 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. An indole compound having the structural formula shown in formula (I): Equation (I); in, At least one of R1, R2, R3, R4, R5, R6, and R7 has the following formula (Hy 1 The structure shown is as follows: Formula (Hy 1 ); Where * indicates a connection site; L1 represents 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 R8 is selected from any of the following groups: alkylthionyl group, carboxylic acid group, and sulfonic acid group; In R1, R2, R3, R4, R5, R6, and R7, the expression (Hy) is not valid. 1 In the case of the structure shown, each group is independently selected from hydrogen, halogen, nitro, hydroxyl, substituted or unsubstituted C1~C. 30 Alkyl, substituted or unsubstituted C1~C 30 Alkoxy, substituted or unsubstituted C1~C 30 Alkylthio, substituted or unsubstituted C6~C 30 aryl, substituted or unsubstituted C6~C 30 arylamino, substituted or unsubstituted C3~C 30 heteroaryl, substituted or unsubstituted C3~C 30 heteroarylamino, substituted or unsubstituted C3~C 12 Any one of the cycloalkyl 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 Alkylthio, C6~C 30 Aryl, C3~C 30 One or at least two of the heteroaryl groups.

2. The indole compound according to claim 1, wherein, Any two adjacent groups in R1, R2, R3, R4, R5, R6, and R7 do not fuse into a ring.

3. The indole compound according to claim 1, wherein, R1, R2, R3, R4, R5, R6, and R7 are each independently selected from C1 to C2. 12 Alkyl, C1~C 12 Alkoxy, C1~C 12 Any one of the alkylthio groups; L1 is C1~C 12 Alkylene, C1~C 12 alkeneoxy group, C1~C 12 One of the alkylthio groups.

4. The indole compound according to claim 1, wherein, R1, R2, R3, R4, R5, R6, and R7 are each independently selected from hydrogen, halogen, methyl, ethyl, isopropyl, tert-butyl, substituted or unsubstituted naphthyl, substituted or unsubstituted phenanthryl, substituted or unsubstituted anthracene, C6~C 30 Arylamino, substituted or unsubstituted phenyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophene, substituted or unsubstituted fluorenyl; L1 is C1~C 12 Straight-chain alkylene; In cases where the substituted or unsubstituted groups have substituents, the substituents are selected from one or a combination of at least two of methoxy, methyl, ethyl, isopropyl, tert-butyl, methylthio, phenyl, and carbazole.

5. The indole compound according to claim 1, wherein, Any one of R2, R3, R4, R5, R6, and R7 has the formula (Hy 1 The structure shown in the diagram, where R2, R3, R4, R5, R6, and R7 are not equal to the formula (Hy). 1 In the case of the structure shown, each element is independently selected from hydrogen, halogen, C1~C2. 12 Alkyl, C6~C 30 Any of the aryl groups; R1 is C1~C 12 alkyl.

6. The indole compound according to claim 5, wherein, L1 is C1~C 12 Alkylene, R8 is a phosphate group.

7. The indole compound according to claim 1, wherein, The indole compounds have the following formulas (I1) to (I 71 The structure shown is as follows: Equation (I1); Equation (I2); Equation (I3); Equation (I4); Equation (I5); Equation (I6); Equation (I7); Equation (I8); Equation (I9); Equation (I 10 ); Equation (I 11 ); Equation (I 12 ); Equation (I 13 ); Equation (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 ); Equation (I 24 ); Equation (I 25 ); Equation (I 26 ); Equation (I 27 ); Equation (I 28 ); Equation (I 29 ); Equation (I 30 ); Equation (I 31 ); Equation (I 32 ); Equation (I 33 ); Equation (I 34 ); Equation (I 35 ); Equation (I 36 ); Equation (I 37 ); Equation (I 38 ); Equation (I 39 ); Equation (I 40 ); Equation (I 41 ); Equation (I 42 ); Equation (I 43 ); Equation (I 44 ); Equation (I 45 ); Equation (I 46 ); Equation (I 47 ); Equation (I 48 ); Equation (I 49 ); Equation (I 50 ); Equation (I 51 ); Equation (I 52 ); Equation (I 53 ); Equation (I 54 ); Equation (I 55 ); Equation (I 56 ); Equation (I 57 ); Equation (I 58 ); Equation (I 59 ); Equation (I 60 ); Equation (I 61 ); Formula (I 62 ); Formula (I 63 ); Equation (I 64 ); Equation (I 65 ); Equation (I 66 ); Equation (I 67 ); Equation (I 68 ); Formula (I 69 ); Formula (I 70 ); Equation (I 71 ).

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 an indole compound 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, copper ions, zinc ions, gallium ions, tin ions, and calcium ions; and X includes one or more of fluoride ions, chloride ions, bromide ions, iodide ions, thiocyanate ions, tetrafluoroborate ions, hexafluorophosphate ions, formate ions, and acetate ions.

10. The solar cell according to claim 8, wherein, The substrate is a crystalline silicon bottom cell.

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