Solar cell and preparation method thereof, photovoltaic module, power consumption and power generation device

Abstract

This application provides a solar cell and its fabrication method, a photovoltaic module, and an electricity consumption and power generation device. The solar cell includes a first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer. The perovskite light-absorbing layer is located between the first electrode layer and the second electrode layer, and the hole transport layer is located between the first electrode layer and the perovskite light-absorbing layer. The hole transport layer includes a cross-linked compound having structural unit (Ⅰ). Thus, the self-assembled monomolecules in the hole transport layer form a cross-linked structure through a dual-nitrogen cross-linking agent, thereby improving the stability between the self-assembled monomolecules. Compared to uncross-linked self-assembled monomolecules, it is less prone to desorption, improving the morphology and structural stability of the hole transport layer, and thus enhancing the photoelectric performance and stability of the solar cell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a solar cell and its preparation method, a photovoltaic module, and an electricity consumption and power generation device. Background Technology

[0002] Solar cells are a new type of photovoltaic device that directly converts solar radiation energy into electrical energy using the photovoltaic effect. Taking perovskite solar cells as an example, they use perovskite material as the light-absorbing layer and have advantages such as low cost, high low-light efficiency, and wide application scenarios. They are an excellent choice for next-generation mass-produced photovoltaic cells, can alleviate the energy crisis, and are one of the key development directions for new energy sources. However, current solar cells suffer from low stability in practical applications, leading to a decline in their photoelectric performance. Summary of the Invention

[0003] To achieve the above objectives, this application provides a solar cell and its preparation method, a photovoltaic module, and an electricity consumption and power generation device.

[0004] A first aspect of this application provides a solar cell comprising a first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer, wherein the perovskite light-absorbing layer is located between the first electrode layer and the second electrode layer, and the hole transport layer is located between the first electrode layer and the perovskite light-absorbing layer, the hole transport layer comprising a cross-linking compound having a structural unit (Ⅰ).

[0005] (I);

[0006] Wherein, * represents the linking site; Ar is the head group, R6 is the anchoring group, and L is the linking group that connects the head group Ar and the anchoring group R6;

[0007] R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl;

[0008] R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

[0009] The solar cell described above in this application has a hole transport layer comprising the aforementioned cross-linked compound, wherein the linking group L and the head group Ar and anchoring group R6 connected to the linking group L form -Ar-L-R6-, which can be derived from self-assembled monomolecules and has good hole transport performance. Adjacent -Ar-L-R6- are connected by -CH(R1)-R2-CH(R3)- to form a cross-linked structure, thereby improving the stability between self-assembled monomolecules. Compared with uncross-linked self-assembled monomolecules, it is less prone to desorption, thus improving the morphology and structural stability of the hole transport layer, thereby improving the photoelectric performance and stability of the solar cell.

[0010] In some embodiments, one or more of the following features are present:

[0011] (1) R1 and R3 each independently include halogen-substituted or unsubstituted C1~C10 alkyl groups;

[0012] (2) R2 includes substituted or unsubstituted C1~C10 alkylene groups and substituted or unsubstituted C5~C30 aryl groups or substituted or unsubstituted heteroaryl groups connected to both ends of the substituted or unsubstituted C1~C10 alkylene groups.

[0013] For R1 and R3, unsubstituted C1-C10 alkyl groups exhibit better hydrophilicity than halogen-substituted C1-C10 alkyl groups, thus forming a hole transport layer with better hydrophilicity. This facilitates the solution-based spreading of the perovskite absorber layer on the surface of the hydrophilic hole transport layer, reducing or avoiding the problems of local agglomeration or uneven thickness leading to numerous pores in the perovskite film, thereby improving the quality and photoelectric properties of the perovskite absorber film. Using these groups in R2 allows for controlled reactivity, improving process operability.

[0014] In some embodiments, R2 has the following structure:

[0015] ;

[0016] Alternatively, R2 has the following structure:

[0017] ;

[0018] Where * represents a connection site;

[0019] m is an integer from 1 to 10;

[0020] R4 and R5 each independently include hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C5-C30 aryl or substituted or unsubstituted heteroaryl; optionally, R4 and R5 each independently include halogen-substituted or unsubstituted C1-C10 alkyl.

[0021] In some embodiments, one or more of the following features are present:

[0022] (1) The head group Ar includes substituted or unsubstituted C6~C30 aryl, substituted or unsubstituted C3~C30 heteroaryl or substituted or unsubstituted C6~C30 aromatic amino groups;

[0023] (2) The linking group L includes one or more of a single bond, a substituted or unsubstituted C1~C10 alkylene group, an alkenyl group, a substituted or unsubstituted C5~C30 aryl group, or a substituted or unsubstituted heteroaryl group;

[0024] (3) The anchoring group R6 includes an oxyacid group or its salt.

[0025] Self-assembled monomolecules can be anchored on a substrate via the anchoring group R6, thus exhibiting good self-assembly film-forming properties.

[0026] In some embodiments, one or more of the following features are present:

[0027] (1) In the head group Ar, the C6~C30 aryl group includes substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthraquinone, substituted or unsubstituted phenanthryl, substituted or unsubstituted alkyl or substituted or unsubstituted pyrene;

[0028] (2) In the head group Ar, the C3~C30 heteroaryl group includes substituted or unsubstituted carbazole group, substituted or unsubstituted dibenzocarbazole group, substituted or unsubstituted dibenzopyridyl group or substituted or unsubstituted naphthalimide group;

[0029] (3) In the head group Ar, the C6~C30 aromatic amino groups include substituted or unsubstituted triphenylamino groups;

[0030] (4) The linking group L includes substituted or unsubstituted C1~C10 alkylene groups;

[0031] (5) The anchoring group R6 includes one or more of the following: phosphonic acid group, phosphonic acid group, sulfonic acid group, sulfinic acid group, carboxylic acid group, boric acid group and silicate group and their salts.

[0032] In some embodiments, the crosslinked compound has a structural unit (Ⅰ-1):

[0033] ;

[0034] Among them, R S1The groups include one or more of H, C1-C30 alkyl, C1-C30 alkoxy, heterocyclic groups containing 3-20 cyclic atoms, aryl groups containing 5-20 cyclic atoms, heteroaryl groups containing 5-20 cyclic atoms, and halogens.

[0035] The cross-linked compound has a structural unit (Ⅰ-1) which has superior hole transport performance.

[0036] In some embodiments, the crosslinked compound has one or more of structural units (I-11) and structural units (I-12):

[0037] (Ⅰ-11)

[0038] (Ⅰ-12)

[0039] Among them, R S1 The groups include one or more of the following: C1-C30 alkyl, C1-C30 alkoxy, heterocyclic group containing 3-20 cyclic atoms, aryl group containing 5-20 cyclic atoms, heteroaryl group containing 5-20 cyclic atoms, and halogen.

[0040] In some embodiments, one or more of the following features are present:

[0041] (1) The thickness of the hole transport layer is 0.1 nm to 10 nm;

[0042] (2) The hole transport layer further includes a self-assembled monomolecular compound existing as a single molecule; optionally, the molar ratio of the self-assembled monomolecular compound existing as a single molecule in the hole transport layer to the self-assembled monomolecular compound contained in the crosslinking compound is ≤1:1, and may be further (0.25~0.5):1.

[0043] The hole transport layer exists in a mixture of both types of compounds. For example, single-molecule self-assembled monomolecular compounds can fill the gaps between the cross-linked compounds, thereby improving the film quality and enhancing the photoelectric performance of the solar cell. Further controlling the molar ratio of single-molecule self-assembled monomolecular compounds in the hole transport layer to those contained in the cross-linked compounds within this range allows for better control of the single-molecule self-assembled monomolecular compounds filling the gaps between the cross-linked compounds, thus improving the coverage of the hole transport layer, enhancing the uniformity of the perovskite film, and improving the photoelectric performance of the solar cell. Simultaneously, the cross-linking between SAMs makes it difficult for SAMs to desorb and diffuse into the perovskite layer, which helps improve the stability of the solar cell.

[0044] A second aspect of this application provides a method for preparing a solar cell, comprising the following steps:

[0045] A first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer are formed in a stacked configuration.

[0046] The formation of the hole transport layer includes the following steps:

[0047] The hole transport material precursor liquid is coated into a film and then cross-linked and cured to form the hole transport layer.

[0048] The hole transport material precursor liquid comprises a self-assembled monomolecular compound and a dual nitrogen crosslinking agent; the self-assembled monomolecular compound comprises a head group Ar, an anchoring group R6, and a linking group L connecting the head group Ar and the anchoring group R6;

[0049] The dual nitrogen crosslinking agent has the structure shown in formula (1):

[0050] (1),

[0051] R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl;

[0052] R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

[0053] The above preparation method eliminates the need for complex steps such as introducing crosslinking sites into the self-assembled monomolecules, simplifying the process and avoiding potential changes in the hydrophilicity and energy levels of the self-assembled monomolecules. This results in a solar cell with a simple fabrication process and strong applicability to self-assembled monomolecules. Solution self-assembly for film formation is a simple, efficient, and cost-effective method.

[0054] In some embodiments, the dual nitrogen crosslinking agent has the structure shown in formula (1-a):

[0055] (1-a);

[0056] Optionally, the dual nitrogen crosslinking agent has the structure shown in formula (1-a1):

[0057] (1-a1);

[0058] Where m is an integer from 1 to 10;

[0059] R4 and R5 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl;

[0060] Optionally, R4 and R5 each independently include halogen-substituted or unsubstituted C1-C10 alkyl groups.

[0061] In some embodiments, the self-assembled monomolecular compound includes one or more of 2PACz, 4PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, or Me-4PACz.

[0062] In some embodiments, one or more of the following features are present:

[0063] (1) In the hole transport material precursor solution, the molar ratio of the self-assembled monomolecular compound and the dual nitrogen crosslinking agent is (1~2):1, which can be (1.25~1.5):1;

[0064] (2) In the hole transport material precursor solution, the molar concentration of the self-assembled monomolecular compound is 0.00065 mol / mL to 0.0065 mol / mL, and can be selected as 0.0009 mol / mL to 0.004 mol / mL;

[0065] (3) The cross-linking curing is carried out under heating or light.

[0066] In some embodiments, the heating temperature is 90°C to 110°C, and / or the heating time is 10 min to 40 min;

[0067] The light source is ultraviolet light.

[0068] By controlling the molar ratio of self-assembled monomolecular compounds and diazonium crosslinking agents within this range, the diazonium crosslinking agent can be almost completely consumed, reducing the adverse effects of unreacted diazonium crosslinking agent in the hole transport layer. Furthermore, when the hole transport layer also includes self-assembled monomolecular compounds existing as single molecules, it is also beneficial to control the proportion of these single-molecule self-assembled monomolecular compounds filling the gaps between the crosslinking compounds, thereby improving coverage, enhancing the uniformity of perovskite film formation, and improving the photoelectric performance of the solar cell. Simultaneously, the crosslinking between SAMs makes it difficult for SAMs to desorb and diffuse into the perovskite layer, which is beneficial to improving the stability of the solar cell.

[0069] In a third aspect, this application provides a hole transport material precursor liquid, comprising a self-assembled monomolecular compound and a dual nitrogen crosslinking agent;

[0070] The self-assembled monomolecular compound includes a head group Ar, an anchoring group R6, and a linking group L connecting the head group Ar and the anchoring group R6;

[0071] The dual nitrogen crosslinking agent has the structure shown in formula (1):

[0072] (1),

[0073] R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl;

[0074] R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

[0075] In a fourth aspect of this application, a hole transport layer is provided, wherein the hole transport layer is the hole transport layer described in the first aspect of this application, or is the hole transport layer made from the hole transport material precursor liquid provided in the third aspect of this application.

[0076] In a fifth aspect, this application provides a photovoltaic module, including a solar cell according to the first aspect of this application or a solar cell prepared by the preparation method according to the second aspect of this application.

[0077] In a sixth aspect of this application, an electrical device is provided, including a solar cell according to the first aspect of this application, a solar cell prepared by the preparation method of the second aspect of this application, or a photovoltaic module according to the fifth aspect of this application.

[0078] A seventh aspect of this application provides a power generation device, including a solar cell according to the first aspect of this application, a solar cell prepared by the preparation method of the second aspect of this application, or a photovoltaic module according to the fifth aspect of this application.

[0079] The electrical appliances and power generation devices of this application include the solar cells provided in this application, and therefore have at least the same advantages as the solar cells.

[0080] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0081] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0082] Figure 1 This is a schematic diagram of a solar cell according to one embodiment of this application.

[0083] Figure 2 The PCE curves for Example 2 and Comparative Example 1 of this application during MPPT tracking time of 0~160h are shown.

[0084] Explanation of reference numerals in the attached figures:

[0085] 1. Solar cell; 11. Substrate; 12. First electrode layer; 13. Hole transport layer; 14. Perovskite light absorption layer; 15. Electron transport layer; 16. Second electrode layer. Detailed Implementation

[0086] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0087] The "range" disclosed in this application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be combined arbitrarily, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this document; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, stating that a parameter is an integer ≥2 is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, stating that a parameter is an integer selected from "2-10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0088] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0089] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0090] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0091] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0092] In this application, unless otherwise specified, A (e.g., B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0093] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0094] In this application, the term "alkyl" refers to a monovalent residue formed by the loss of a hydrogen atom from a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C1-C6 alkyl," refer to alkyl groups containing 1 to 6 carbon atoms, and each occurrence can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, or C6 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(CH3)CH 2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (-CH2CH2CH(C H3)2), 2-methyl-1-butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3), 4- Methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3). Understandably, "alkylene" refers to a subunit derived from "alkyl" by removing one hydrogen atom.

[0095] In this application, "aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing one hydrogen atom. It can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For polycyclic rings, at least one is an aromatic ring system. For example, "C6-C30 aryl" refers to an aryl group containing 6 to 30 carbon atoms, and each occurrence can be independently C6, C7, C8, C9, C10, C15, C20, C25, or C30 aryl. Suitable examples include, but are not limited to, benzene, biphenyl, naphthalene, anthracene, phenanthrene, dinaphthalene, triphenylene, and their derivatives.

[0096] In this application, "arylamino group" refers to a group obtained by substituting an amino group onto an "aryl" group. Without limitation, one, two, or three "aryl" groups can be linked by one amino group. Suitable examples include, but are not limited to, triphenylamino group.

[0097] In this application, "heteroaryl" refers to an aryl group in which at least one carbon atom is replaced by a non-carbon atom, which can be an N atom, an O atom, an S atom, etc. For example, "C3~C30 heteroaryl" refers to a heteroaryl group containing 3 to 30 carbon atoms, and each occurrence can be independently C3 heteroaryl, C4 heteroaryl, C5 heteroaryl, C6 heteroaryl, C7 heteroaryl, C8 heteroaryl, C9 heteroaryl, C10 heteroaryl, C15 heteroaryl, C20 heteroaryl, C25 heteroaryl, and C30 heteroaryl. Suitable examples include, but are not limited to: furanyl, benzofuranyl, thiophenyl, benzothiophenyl, pyrroleyl, pyrazolyl, triazolyl, imidazoyl, oxazolyl, oxadiazolyl, thiazoyl, tetrazolyl, indolyl, carbazoyl, pyrroloimidazoyl, pyrrolopyrroleyl, thiophenolopyrroleyl, thiophenolothiophenyl, furanolopyrroleyl, furanolofuranyl, thiophenolofuranyl, benzoisooxazolyl, benzoisothiazoyl, benzoimidazoyl, pyridinyl, pyrazinyl, pyrimidinyl, triazinyl, quinolinyl, isoquinolinyl, o-diazanaphthyl, quinoxalinyl, phenanthridine, primidinyl, quinazolinyl, and quinazolinoneyl.

[0098] In this application, when no linking site is specified in the group, it means that any linkable site in the group is selected as the linking site.

[0099] In this application, the single bonds connecting the substituents extend through the corresponding ring, indicating that the substituent can be connected to any optional position on the ring.

[0100] In this application, when the same substituent, such as R, appears multiple times, each R can be independently selected from different groups.

[0101] In this application, "substituted or unsubstituted" means that the defined group may or may not be substituted. When the defined group is substituted, it should be understood that it may be substituted by a group acceptable in the art, including but not limited to: C1-C30 alkyl, C1-C30 alkoxy, heterocyclic group containing 3-20 cyclic atoms, aryl group containing 5-20 cyclic atoms, heteroaryl group containing 5-20 cyclic atoms, and one or more combinations of halogens. Further, substituents include but are not limited to: C1-C10 alkyl, C1-C10 alkoxy, heterocyclic group containing 3-15 cyclic atoms, aryl group containing 5-15 cyclic atoms, heteroaryl group containing 5-15 cyclic atoms, and one or more combinations of halogens.

[0102] In this application, halogens include one or more of F, Cl, Br, and I.

[0103] Solar cells, also known as photovoltaic cells, are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. Perovskite solar cells are solar cells that utilize perovskite material as the light-absorbing material. The photoelectric conversion principle of perovskite solar cells is as follows: Incident light (e.g., sunlight) enters the device and reaches the perovskite light-absorbing layer, where it is absorbed. Under the excitation of the incident light, the perovskite light-absorbing layer generates electron-hole pairs. Under the action of an electric field, the holes and electrons separate, with electrons transferring to one electrode and holes transferring to the other. Subsequently, a circuit is formed through an external circuit, which can be used to drive a load.

[0104] Compared with other solar cells, solar cells using perovskite light-absorbing layers have higher theoretical photoelectric conversion efficiency. For solar cells with perovskite light-absorbing layers, self-assembled monolayers (SAMs) are generally placed on the lower surface of the perovskite layer as hole transport layers to passivate the lower surface of the perovskite layer and extract and transport holes. However, in practical applications, their photoelectric performance and stability are still relatively low.

[0105] Specifically, self-assembled monomolecular compounds have poor stability under photothermal conditions because they are small molecules and are subject to desorption, which leads to changes in the morphology of the self-assembled monolayer, and consequently causes a decrease in the photoelectric performance and stability of solar cells.

[0106] Based on this, one embodiment of this application provides a solar cell, including a first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer. The perovskite light-absorbing layer is located between the first electrode layer and the second electrode layer, and the hole transport layer is located between the first electrode layer and the perovskite light-absorbing layer. The hole transport layer includes a crosslinking compound. The crosslinking compound has structural unit (Ⅰ):

[0107] (I);

[0108] Wherein, * represents the linking site; Ar is the head group, R6 is the anchoring group, and L is the linking group that connects the head group Ar and the anchoring group R6;

[0109] R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl;

[0110] R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

[0111] The solar cell described above in this application has a hole transport layer comprising the aforementioned cross-linked compound, wherein the linking group L and the head group Ar and anchoring group R6 connected to the linking group L form -Ar-L-R6-, which can be derived from self-assembled monomolecules and has good hole transport performance. Adjacent -Ar-L-R6- are connected by -CH(R1)-R2-CH(R3)- to form a cross-linked structure, thereby improving the stability between self-assembled monomolecules. Compared with uncross-linked self-assembled monomolecules, it is less prone to desorption, thus improving the morphology and structural stability of the hole transport layer, thereby improving the photoelectric performance and stability of the solar cell.

[0112] The structural formula of -CH(R1)-R2-CH(R3)- is shown below:

[0113] .

[0114] The adjacent -Ar-L-R6- groups of the above crosslinked compounds are connected by -CH(R1)-R2-CH(R3)- to form the crosslinked structural units shown below:

[0115] .

[0116] Furthermore, since adjacent -Ar-L-R6- forms a cross-linked structure through -CH(R1)-R2-CH(R3)-, and -CH(R1)-R2-CH(R3)- does not form a strong conjugation with the adjacent -Ar-L-R6-, the energy level after cross-linking is basically unchanged compared to Ar-L-R6, thus avoiding the problem of energy level mismatch in Ar-L-R6 after cross-linking.

[0117] The solar cell described in this application has a hole transport layer obtained by crosslinking a self-assembled monomolecular compound with a diazo crosslinking agent. The self-assembled monomolecular compound has the structure Ar-L-R6. The diazo crosslinking agent includes two bisacrididine ring groups. The bisacrididine ring groups in the diazo crosslinking agent can act on CH bonds, thus it can directly react with the CH bonds in the self-assembled monomolecular compound. The diazo crosslinking agent achieves crosslinking by reacting the two bisacrididine ring groups with two Ar-L-R6 molecules respectively, without the need for complex steps such as introducing crosslinking sites into the self-assembled monomolecular compound. This simplifies the process and avoids problems such as changes in the hydrophilicity and energy levels of the self-assembled monomolecular compound. The solar cell described above not only has a simple fabrication process but also has strong applicability to self-assembled monomolecular compounds. Understandably, the self-assembled monomolecular compound includes at least one CH bond.

[0118] The structure and composition of the above-mentioned cross-linked compounds can be detected by nuclear magnetic resonance mass spectrometry.

[0119] Understandably, the above-described crosslinked compound has the above-described structural unit (Ⅰ). In some embodiments, structural unit (Ⅰ) is a repeating unit of the crosslinked compound, which has the following structure:

[0120] Where q is the degree of aggregation. As an example, q can be an integer greater than or equal to 1, such as any integer from 1 to 10000, or further, from 1 to 1000, or from 1 to 500, or from 1 to 100, or from 1 to 50.

[0121] In some embodiments, -CH(R1)-R2-CH(R3)- is derived from a dual nitrogen crosslinking agent having the structure shown in formula (1):

[0122] (1),

[0123] The definitions of R1, R2, and R3 are as described above.

[0124] In some embodiments, R1 and R3 each independently comprise substituted or unsubstituted C1-C10 alkyl groups, and further comprise halogen-substituted or unsubstituted C1-C10 alkyl groups. R1 and R3 can be the same or different. For R1 and R3, unsubstituted C1-C10 alkyl groups have better hydrophilicity than halogen-substituted C1-C10 alkyl groups, thus forming a hole transport layer with better hydrophilicity. This facilitates the solution-based spreading of the perovskite light-absorbing layer on the surface of the hole transport layer with better hydrophilicity, reducing or avoiding the problems of local agglomeration or uneven thickness forming numerous pores in the perovskite film, which is beneficial to improving the quality and photoelectric performance of the perovskite light-absorbing layer film.

[0125] In some embodiments, the combination of multiple substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups in R2 includes combinations of at least one substituted or unsubstituted C5-C30 aryl group or substituted and unsubstituted heteroaryl group and substituted or unsubstituted C1-C10 alkylene groups. Using these groups in R2 allows for appropriate control of its reactivity and improves process operability.

[0126] Furthermore, the combination described above in R2 includes substituted or unsubstituted C1-C10 alkylene groups and substituted or unsubstituted C5-C30 aryl groups or substituted or unsubstituted heteroaryl groups connected to both ends of the substituted or unsubstituted C1-C10 alkylene groups.

[0127] Furthermore, the above-described combination in R2 includes substituted or unsubstituted C1-C10 alkylene groups and substituted or unsubstituted phenyl groups connected to both ends of the substituted or unsubstituted C1-C10 alkylene groups. As a non-limiting example, R2 has the following structure:

[0128] .

[0129] Alternatively, R2 has the following structure:

[0130] ;

[0131] Where * represents a connection site;

[0132] Where m is any integer from 1 to 10; further, m is any integer from 1 to 5.

[0133] R4 and R5 each independently include hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C5-C30 aryl or substituted or unsubstituted heteroaryl; optionally, R4 and R5 each independently include halogen-substituted or unsubstituted C1-C10 alkyl.

[0134] Understandably, the self-assembled monomolecular compound Ar-L-R6 includes a head group Ar, an anchoring group R6, and a linking group L connecting the head group Ar and the anchoring group R6. The self-assembled monomolecular compound can be anchored on a substrate via the anchoring group R6, thus exhibiting good self-assembly film-forming properties. It then undergoes cross-linking and curing with a dual-nitrogen cross-linking agent to form the aforementioned hole transport layer.

[0135] In this application, Ar, L, and R6 in structural unit (Ⅰ) have the same definitions as in the self-assembled monomolecular compound Ar-L-R6.

[0136] Understandably, the self-assembled single-molecule compound (SAM molecule) has an anchoring group R6 that serves to fix the self-assembled single-molecule compound to the surface of a substrate (such as the first electrode layer).

[0137] The anchoring group R6 includes an oxyacid group or its salt.

[0138] Understandably, the salt of an oxoacid, i.e., an oxoacid salt group, refers to a group formed by an oxoacid group and a cation, wherein the cation includes, but is not limited to, metal cations and organic cations. For example, a metal cation can be one or more of sodium ions and potassium ions, and an organic cation can be an ammonium ion.

[0139] Without limitation, the oxyacid groups in the anchoring group R6 include one or more of the following: phosphonic acid group -PO(OH)2, hypophosphonic acid group -POR3(OH), sulfonic acid group -SO3H, sulfinic acid group -SO2H, carboxylic acid group -COOH, boric acid group, and silicate group. In other words, the anchoring group R6 includes one or more of the following: phosphonic acid group, hypophosphonic acid group, sulfonic acid group, sulfinic acid group, carboxylic acid group, boric acid group, and silicate group, and their salts.

[0140] Furthermore, R6 includes one or more of phosphonic acid groups, hypophosphonic acid groups, carboxylic acid groups, and their salts, which is more conducive to the bonding between the self-assembled monomolecular compound and the first electrode layer.

[0141] Understandably, the head group Ar is a functional group in the self-assembled single-molecule compound (SAM molecule). Specifically, the head group Ar in the self-assembled single-molecule compound (SAM molecule) includes substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl, or substituted or unsubstituted C6-C30 aromatic amino groups. Without limitation, the C6-C30 aryl groups include substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracene, substituted or unsubstituted phenanthryl, substituted or unsubstituted phenyl, or substituted or unsubstituted pyrene; the C3-C30 heteroaryl groups may include substituted or unsubstituted carbazole, substituted or unsubstituted dibenzocarbazole, substituted or unsubstituted dibenzopyridyl, or substituted or unsubstituted naphthalimide; and the C6-C30 aromatic amino groups include substituted or unsubstituted triphenylamino groups.

[0142] In some embodiments, the head group Ar comprises a substituted or unsubstituted C3-C30 heteroaryl group. The heteroatom in the heteroaryl group comprises one or more of N, O, and S, for example, at least N. Further, the linking group L can be linked to the anchoring group R6 via a heteroatom in the heteroaryl group.

[0143] Understandably, the linking group L is the linking group in the self-assembled single-molecule compound (SAM molecule), which mainly plays the role of spacer and support, like a "bridge" connecting the anchoring group R6 and the head group Ar.

[0144] In some embodiments, L comprises a single bond, a substituted or unsubstituted C1-C10 alkylene group, an alkenyl group, a substituted or unsubstituted C5-C30 aryl group, or a substituted or unsubstituted heterocyclic aryl group. It is understood that when L is a single bond, it means that R6 and Ar are directly linked by a single bond. Further, L comprises a substituted or unsubstituted C1-C10 alkylene group, an alkenyl group, a substituted or unsubstituted C5-C30 aryl group, or a substituted or unsubstituted heterocyclic aryl group.

[0145] Furthermore, in the presence of substitution, the substituents of the C1-C10 alkylene groups include any one of halogen groups, alkoxy groups, oxyacid groups, C6-C15 aromatic groups, and heteroaromatic groups with 5-15 cyclic atoms.

[0146] In some embodiments, L includes substituted or unsubstituted C1-C10 alkylene groups, and further includes C1-C5 alkylene groups.

[0147] In some of these embodiments, the crosslinking compound has a structural unit (Ⅰ-1):

[0148] ;

[0149] Among them, R S1 The functional groups include one or more of H, C1-C30 alkyl, C1-C30 alkoxy, heterocyclic groups containing 3-20 cyclic atoms, aryl groups containing 5-20 cyclic atoms, heteroaryl groups containing 5-20 cyclic atoms, and halogens. R1, R2, R3, L, and R6 are defined as described above. The cross-linked compound has structural unit (Ⅰ-1), which exhibits superior hole transport properties.

[0150] Furthermore, the repeating units of the crosslinked compound have the following structure:

[0151] , where q is the degree of aggregation.

[0152] In some embodiments, the aforementioned crosslinking compound can be prepared by crosslinking a self-assembled monomolecular compound with a diazo crosslinking agent, wherein the self-assembled monomolecular compound includes a structure having the structure shown in formula (2):

[0153] Equation (2),

[0154] Among them, R S1The group is a substituent, including one or more of H, C1-C30 alkyl, C1-C30 alkoxy, heterocyclic group containing 3-20 cyclic atoms, aryl group containing 5-20 cyclic atoms, heteroaryl group containing 5-20 cyclic atoms, and halogen. Further, R... S1 The groups include one or more of C1-C10 alkyl, C1-C10 alkoxy, heterocyclic groups containing 3-15 cyclic atoms, aryl groups containing 5-15 cyclic atoms, heteroaryl groups containing 5-15 cyclic atoms, and halogens. L and R6 are defined as described above.

[0155] The cross-linked compound has one or more of structural units (I-11) and structural units (I-12):

[0156] (Ⅰ-11)

[0157] (Ⅰ-12); Among them, R S1 The group includes one or more of the following: C1-C30 alkyl, C1-C30 alkoxy, heterocyclic group containing 3-20 cyclic atoms, aryl group containing 5-20 cyclic atoms, heteroaryl group containing 5-20 cyclic atoms, and halogen; that is, R S1 The group is not H.

[0158] In equation (2), R S1 If the group is not H, then the self-assembled monomolecular compound of formula (2) tends to crosslink with the diazo crosslinking agent to form structural unit (Ⅰ-11); in formula (2), R S1 If the group is H, then the self-assembled monomolecular compound of formula (2) tends to crosslink with a diazo crosslinking agent to form structural unit (Ⅰ-12). Understandably, the self-assembled monomolecular compound adopts one or more compounds of formula (2), thus forming one or more of the above-mentioned structural units (Ⅰ-11) and structural units (Ⅰ-12).

[0159] As an example, the crosslinked compound may have one of the following structures, wherein R S1 Groups other than H:

[0160] or .

[0161] As a non-restrictive example of equation (2), the structure of equation (2) can be as follows:

[0162] (2-1); Where n is an integer from 1 to 10; further, n is an integer from 1 to 5. Further, R S1The groups include one or more of C1-C10 alkyl and C1-C10 alkoxy groups.

[0163] As a non-limiting example, the self-assembled monomolecular compounds include one or more of 2PACz, 4PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, or Me-4PACz. These self-assembled monomolecular compounds exhibit good hole transport properties.

[0164] The structural formula of 2PACz is as follows:

[0165] .

[0166] The structural formula of 4PACz is as follows:

[0167] .

[0168] MeO-2PACz's Chinese name is (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, and its structural formula is as follows:

[0169] .

[0170] Me-2PACz's Chinese name is 2-(3,6-dimethyl-9H-carbazole-9-yl)ethylphosphonic acid, and its structural formula is as follows:

[0171] .

[0172] MeO-4PACz's Chinese name is [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid, and its structural formula is as follows:

[0173] .

[0174] Me-4PACz's Chinese name is [4-(3,6-dimethyl-9H-carbazole-9-yl)butylphosphonic acid], and its structural formula is as follows:

[0175] .

[0176] In some embodiments, the hole transport layer further includes a self-assembled monomolecular compound existing as a single molecule. Further, this self-assembled monomolecular compound existing as a single molecule is mixed with the aforementioned crosslinking compound, both of which can be attached to the substrate via an anchoring group R6. The hole transport layer exists in a mixture of both; for example, the self-assembled monomolecular compound existing as a single molecule can fill the gaps in the aforementioned crosslinking compound, thereby improving its coverage, enhancing the uniformity of perovskite film formation, and improving the photoelectric performance of the solar cell.

[0177] Understandably, the hole transport layer is a monolayer with a thickness on the nanometer scale. In some embodiments, the thickness of the hole transport layer is 0.1 nm to 10 nm. As an example, the thickness of the hole transport layer can be 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or within a range defined by any two of the above values, such as 0.1 nm to 2 nm.

[0178] In some of these embodiments, such as Figure 1 As shown, the solar cell 1 includes a first electrode layer 12, a hole transport layer 13, a perovskite light-absorbing layer 14, an electron transport layer 15, and a second electrode layer 16 stacked together. The hole transport layer 13 includes a cross-linked compound formed by the aforementioned self-assembled monomolecular compound and a dual-nitrogen cross-linking agent.

[0179] Furthermore, the hole transport layer is a film of a cross-linked compound formed by the self-assembled monomolecular compound and the dual nitrogen cross-linking agent.

[0180] Without limitation, the hole transport layer 13 can be directly used as the hole transport layer of the perovskite solar cell, or other hole transport layers can be additionally provided between the first electrode layer 12 and the perovskite light-absorbing layer 14. Figure 1 (Not shown in the image). A hole transport layer, capable of extracting and transporting hole carriers, and blocking the passage of free electrons. Without limitation, other hole transport layers may include, but are not limited to, one or more of the following materials and their derivatives: 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), polytriarylamine (PTAA), nickel oxide (NiO2). x Materials such as poly(3,4-ethylenedioxythiophene), polystyrene sulfonate (PEDOT:PSS), and WO3 can transport holes and block electrons.

[0181] In some embodiments, at least one of the first electrode layer and the second electrode layer is a transparent electrode for light incident. For example... Figure 1 As shown, in one example, the solar cell 1 also includes a substrate 11. A first electrode layer 12 is disposed on the substrate 11; furthermore, both the first electrode layer 12 and the substrate 11 are made of transparent material, and accordingly, the solar cell is a reverse pin cell. Understandably, in other examples, a second electrode layer 16 may also be disposed on the substrate, and accordingly, the solar cell is a conventional cell.

[0182] The transparent electrode can be a transparent conductive metal oxide electrode. Without limitation, the material of the transparent electrode can be, for example, one or more of the following: FTO (fluorine-doped tin oxide), ITO (tin-doped indium oxide), AZO (aluminum-doped zinc oxide), BZO (boron-doped zinc oxide), IZO (indium zinc oxide), IWO (tungsten-doped indium oxide), lanthanide-doped indium oxide, antimony-doped tin oxide, etc. It is understood that the transparent electrode can use glass as a substrate, or it can use a transparent flexible substrate. Specifically, the material of the transparent flexible substrate can be, for example, an organic polymer material, which can be a mixture of one or more of the following materials in different proportions: polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), and polydimethylsiloxane (PDMS).

[0183] In some embodiments, the second electrode layer comprises a conductive material. Further, the conductive material can be an organic conductive material, an inorganic conductive material, or a combination thereof. Non-limiting examples of inorganic conductive materials include metallic conductive materials. Further, metallic conductive materials can include any one of gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), chromium (Cr), bismuth (Bi), platinum (Pt), magnesium (Mg), or any suitable mixture of the aforementioned elements. The conductive material can include a conductive oxide. Further, the conductive material can be a conductive oxide; non-limiting examples of conductive oxides can include one or more of FTO, ITO, IWO, AZO, etc.

[0184] In some embodiments, the crystal structure of the perovskite light-absorbing layer is ABX3 or A2CDX6. Here, A ions are monovalent cations, B ions are divalent metal cations, C ions are monovalent metal cations, D ions are trivalent metal cations, and X ions are monovalent anions.

[0185] Optionally, A ion is a monovalent cation with a large radius, including one or more organic cations and metal cations. More preferably, the organic cation includes organic amine ions, formamidinyl (HC(NH2)2) ions, etc. + FA + One or more of the following: ) and imidazole groups; more preferably, the metal cation includes lithium ions (Li ions) + Sodium ions (Na) + ), potassium ions (K) + ), rubidium ions (Rb + ), cesium ions (Cs) + One or more of the following. Further, the organic amine ion includes methylamine (CH3NH3). + MA + ), dimethyl diammonium ion (MDA) 2+), phenylethylammonium ion (PEA) + ), oleyl ammonium ions (OA) + ( ), one or more of ethylamino, propylamino, butylamino, pentamino, and hexamino.

[0186] Optionally, the B ion includes Pb. 2+ (lead ions), Sn 2+ (Tin ion), Be 2+ (beryllium ion), Mg 2+ (Magnesium ions), Ca 2+ (calcium ions), Sr 2+ (Strontium ion), Ba 2+ (Barium ions), Zn 2+ (Zinc ions), Ge 2+ (Germanium ions), Fe 2+ (ferrous ion), Mn 2+ Co 2+ (Divalent cobalt ions), Cu 2+ (Divalent copper ions) and Ni 2+ One or more of (divalent nickel ions); more preferably, B ions include Pb. 2+ (Lead ions) and Sn 2+ One or two of (tin ions).

[0187] Optionally, the C ions include Cs + (cesium ion), Ag + (Silver ions), K + (Potassium ions) and Rb + One or more of (rubidium ions).

[0188] Optionally, the D ion includes Bi. 3+ (bismuth ion), Ni 3+ (trivalent nickel ions), Fe 3+ (Fe3+) and Cu 3+ One or more of (trivalent copper ions);

[0189] Optionally, the X ion includes one or more halogens or halogen-like ions, specifically including fluoride ions (F... - ), chloride ions (Cl) - ), bromide ions (Br) - ), iodide ions (I - ), cyanate ions (CN) - ), thiocyanate ions (SCN) - One or more of the following; optionally, X ions include Cl... - ,Br - and I - One or more of them. Further, X includes I.- ,Br - One or two of them. X can be I. - ,Br - Or combinations thereof. In some embodiments, X is I. - .

[0190] It is understandable that the perovskite material in the aforementioned perovskite light-absorbing layer can be selected from Cs. x1 FA 1-x1 PbX3, Cs x1 MA 1-x1 PbX3, Cs m FA n MA 1-m-n PbX3, CsPbX3, MAPbX3, FAPbX3, Cs x1 FA 1-x1 Pb x2 Sn 1-x2 X3, Cs x1 FA 1-x1 Pb x2 Sn 1-x2 X3, Cs m FA n MA 1-m-n Pb x2 Sn 1-x2 X3, CsPb x2 Sn 1-x2 X3, MAPb x2 Sn 1-x2 X3 and FAPb x2 Sn 1-x2 One or more of X3, where 0 < x1 < 1, 0 < x2 < 1, 0 < m < 1, and 0 < n < 1.

[0191] As examples, perovskite materials include CH8I3N2Pb (FAPbI3) and Cs. 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 )3, CsPbBr3, CsPbI3, Cs 0.05 FA 0.95 PbI3 and MA 0.2 FA 0.8 One or more of PbI3.

[0192] In some embodiments, the electron transport layer functions to transport electrons generated by the excitation of the perovskite light-absorbing layer to an adjacent electrode and to prevent hole transport. The electron transport layer may include an electron transport material, which may include one or more of doped or undoped tin oxide, doped or undoped titanium oxide, doped or undoped zinc oxide, or doped or undoped organic molecular materials. The doping element may include one or more of Mg, Zn, Ag, Li, Rb, Ta, and Nb, for example, by doping with chlorides of the above elements. Specifically, the electron transport material may include [6,6]-phenylC 61 Methyl butyrate (PC) 61 BM), [6,6]-phenyl C 71 Methyl butyrate PC 71 BM, Fullerene C 60 Fullerene C 70 One or more of the following: tin dioxide (SnO2), zinc oxide (ZnO), etc.

[0193] Understandably, other film layers can be provided between the film layers of the aforementioned solar cell as needed. For example, optionally, a hole-blocking layer may be provided between the electrode layer and the electron transport layer of the aforementioned solar cell. The material of the hole-blocking layer may include, but is not limited to, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and tin oxide. Alternatively, an electron-blocking layer may be provided between the electrode layer and the hole transport layer of the aforementioned solar cell.

[0194] In some embodiments, perovskite solar cells include single-junction cells and tandem cells. Tandem cells include double-junction cells, triple-junction cells, quadruple-junction cells, etc., which contain perovskite solar cells. Exemplary examples include perovskite-perovskite tandem cells and perovskite-crystalline silicon tandem cells.

[0195] Another embodiment of this application provides a method for fabricating a solar cell, which can be used to fabricate any of the solar cells described above. The method includes the following steps:

[0196] A first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer are formed in a stacked configuration.

[0197] The formation of the hole transport layer includes the following steps:

[0198] A hole transport material precursor liquid is coated into a film and then crosslinked and cured to form the hole transport layer; wherein, the hole transport material precursor liquid includes a self-assembled monomolecular compound and a dual nitrogen crosslinking agent.

[0199] The solar cells prepared by the above method have the same hole transport layer as the solar cells described above, and therefore have at least the same advantages as the solar cells described above, which will not be repeated here.

[0200] Furthermore, the above preparation method does not require complex steps such as introducing crosslinking sites into the self-assembled monomolecule compound, which not only simplifies the process, but also avoids the problem of possible changes in the hydrophilicity and energy level of the self-assembled monomolecule compound. The above solar cell not only has a simple preparation process, but also has strong applicability to self-assembled monomolecule compounds.

[0201] The solution self-assembly method for forming films is simple, efficient, and cost-effective. The methods for coating the mixed solution into films include, but are not limited to, any one of spin coating, spraying, blade coating, and slot coating.

[0202] As described above, the structure of the self-assembled monomolecular compound is Ar-L-R6. In this application, Ar, L, and R6 in structural unit (Ⅰ) have the same definitions as in the self-assembled monomolecular compound Ar-L-R6.

[0203] As described above, the aforementioned dual-nitrogen crosslinking agent has the structure shown in formula (1):

[0204] (1).

[0205] In this application, R1, R2, and R3 in structural unit (Ⅰ) have the same definitions as in the dual nitrogen crosslinking agent.

[0206] The aforementioned dual-nitrogen crosslinking agent can decompose under relatively mild conditions such as heating or light to form two free carbenes, which then react with the carbon-hydrogen bonds on the Ar groups in the self-assembled monomolecular compound to form the aforementioned structural unit (Ⅰ).

[0207] In some embodiments, the dual nitrogen crosslinking agent has the structure shown in formula (1-a):

[0208]

[0209] The definitions of R4 and R5 are the same as above. Furthermore, the dual-nitrogen crosslinking agent has the structure shown in formula (1-a1):

[0210] (1-a1).

[0211] As an example, the dual nitrogen crosslinking agent includes one or more compounds shown in formulas (11) to (12):

[0212] (11)

[0213] (12).

[0214] The structure of self-assembled monomolecules has been described in detail above and will not be repeated here.

[0215] As an example, taking the hole transport layer as a crosslinking agent using 4PACz as SAM and the dual nitrogen crosslinking agent shown in formula (1) for crosslinking reaction, the reaction mechanism is as follows:

[0216] .

[0217] As an example, taking the hole transport layer as a crosslinking reaction using Me-4PACz as SAM and the dual nitrogen crosslinking agent shown in formula (1), the reaction mechanism is as follows:

[0218] .

[0219] Furthermore, the hole transport material precursor solution also includes a solvent, in which a self-assembled monomolecular compound and a dual nitrogen crosslinking agent are dissolved to form the hole transport material precursor solution.

[0220] In some embodiments, the solvent includes one or more of methanol, isopropanol, ethanol, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0221] In some embodiments, the amount of dinitrogen crosslinking agent added to the hole transport material precursor solution is generally small to reduce the adverse effects of unreacted dinitrogen crosslinking agent in the hole transport layer. In some embodiments, the hole transport layer also includes a self-assembled monomolecular compound existing as a single molecule. Further, this self-assembled monomolecular compound existing as a single molecule (or an uncrosslinked self-assembled monomolecular compound) is mixed with the aforementioned crosslinking compound, and both can be attached to the substrate by the anchoring group R6. The type of self-assembled monomolecular compound existing as a single molecule may be the same as or different from the type of self-assembled monomolecular compound in the crosslinking compound.

[0222] In some embodiments, the molar ratio of self-assembled monomolecular compounds and diazonium crosslinking agents in the hole transport material precursor solution is (1~2):1, optionally (1.25~1.5):1. As an example, the diazonium crosslinking agent can be 1:1, 1.25:1, 1.5:1, 1.75:1, 2:1, or any of the above values ​​within this range. Controlling the molar ratio of self-assembled monomolecular compounds and diazonium crosslinking agents within this range allows for the near-complete consumption of the diazonium crosslinking agent, reducing the adverse effects of unreacted diazonium crosslinking agent in the hole transport layer. Furthermore, when the hole transport layer also includes self-assembled monomolecular compounds existing as single molecules, it is beneficial to control the proportion of these single molecules filling the gaps between the crosslinking compounds, thereby improving coverage, enhancing the uniformity of perovskite film formation, and improving the photoelectric performance of the solar cell. Simultaneously, the crosslinking between SAMs makes it difficult for SAMs to desorb and diffuse into the perovskite layer, which is beneficial for improving the stability of the solar cell.

[0223] Furthermore, the molar ratio of the self-assembled monomolecular compound existing as a single molecule in the hole transport layer to the self-assembled monomolecular compound contained in the crosslinking compound is (0~1):1, further ≤1:1, and further possibly (0.25~0.5):1. As an example, the dual-nitrogen crosslinking agent can be 0, 0.1:1, 0.15:1, 0.25:1, 0.3:1, 0.4:1, 0.5:1, or any of the above values ​​as endpoints. By controlling the molar ratio of the self-assembled monomolecular compound and the dual-nitrogen crosslinking agent in the hole transport material precursor liquid, the molar ratio of the self-assembled monomolecular compound existing as a single molecule in the hole transport layer to the self-assembled monomolecular compound contained in the crosslinking compound can be controlled. Further controlling it within this range is beneficial to control the self-assembled monomolecular compound existing as a single molecule to fill the gaps of the crosslinking compound in a better proportion, thereby improving its film formation quality and enhancing the photoelectric performance of the solar cell.

[0224] In some embodiments, the molar concentration of the self-assembled unimolecular compound in the hole transport material precursor solution is 0.00065 mol / mL to 0.0065 mol / mL, optionally 0.0009 mol / mL to 0.004 mol / mL. As an example, this molar concentration can be 0.00065 mol / mL, 0.0007 mol / mL, 0.0008 mol / mL, 0.0009 mol / mL, 0.001 mol / mL, 0.002 mol / mL, 0.003 mol / mL, 0.004 mol / mL, 0.005 mol / mL, 0.006 mol / mL, 0.0065 mol / mL, or any of the above values ​​as endpoints within a range.

[0225] In some embodiments, crosslinking curing can be performed under heat or light. The aforementioned dual-nitrogen crosslinking agent can decompose under the relatively mild and controllable conditions to form two free carbenes, which then react with the carbon-hydrogen bonds of the self-assembled monomolecular compound to produce crosslinking.

[0226] Furthermore, the heating temperature is 90℃~110℃. Furthermore, the heating time is 10min~40min. Specifically, the temperature includes, but is not limited to: 90℃, 92℃, 950℃, 100℃, 103℃, 105℃, 107℃, 110℃ or any range between the two; the time includes, but is not limited to: 10min, 15min, 20min, 25min, 30min, 35min, 40min or any range between the two.

[0227] Furthermore, the light source is ultraviolet light; for example, ultraviolet light irradiation with a wavelength of 350nm can be used.

[0228] In some examples, the material of the perovskite light-absorbing layer includes a perovskite-type metal halide with the chemical formula ABX3. The preparation method of the perovskite light-absorbing layer includes the following steps: mixing material A, BX2 and solvent to obtain a perovskite precursor solution; then coating the perovskite precursor solution onto the corresponding substrate and annealing to obtain the perovskite light-absorbing layer.

[0229] The aforementioned first electrode layer, hole transport layer, electron transport layer, and second electrode layer can be prepared using methods commonly used in the art, including but not limited to solution methods and solid deposition methods. Solution methods include any one of spin coating, spraying, blade coating, and slot coating. Solid deposition methods include any one of vacuum evaporation, sputtering deposition, plasma deposition, ion deposition, and atomic layer deposition (ALD).

[0230] In some embodiments, the step of forming the hole transport layer is performed on the first electrode layer.

[0231] One embodiment of this application provides a hole transport material precursor liquid and its application in the preparation of a hole transport layer.

[0232] The hole transport material precursor solution comprises a self-assembled monomolecular compound and a dual-nitrogen crosslinking agent. Furthermore, the hole transport material precursor solution possesses the same technical features as in the above-described preparation method, and therefore has at least the same advantages as the aforementioned hole transport material precursor solution, which will not be elaborated further here. Furthermore, the hole transport material precursor solution possesses the same self-assembled monomolecular compound and dual-nitrogen crosslinking agent as in the aforementioned solar cell, and therefore has at least the same advantages as the aforementioned hole transport layer, which will not be elaborated further here.

[0233] Another embodiment of this application provides a hole transport layer comprising the aforementioned self-assembled monomolecular compound and a crosslinked compound formed by a dual-nitrogen crosslinking agent. Furthermore, this hole transport layer possesses the technical features and effects described above, which will not be repeated here.

[0234] Other embodiments of this application provide a photovoltaic module, including the solar cell as described above.

[0235] The aforementioned solar cells have high light conversion efficiency and good stability, which can improve the efficiency of photovoltaic modules.

[0236] The aforementioned photovoltaic module includes one or more of the aforementioned solar cells, which can be selected according to specific application scenarios; further, the aforementioned photovoltaic module includes multiple of the aforementioned solar cells, which are connected in series or parallel to form a solar cell. Further, the aforementioned photovoltaic module may also include tandem cells. Tandem cells include, but are not limited to, crystalline silicon / perovskite tandem cells, all-perovskite tandem cells, and thin-film / perovskite tandem cells such as copper indium gallium selenide (CIGS).

[0237] In some embodiments, the photovoltaic module further includes a photovoltaic glass layer, an adhesive layer, and a backsheet.

[0238] The solar cell has an adhesive layer on each of its two surfaces. A backsheet is provided on the surface of one adhesive layer away from the solar cell, and a photovoltaic glass layer is provided on the surface of the other adhesive layer away from the solar cell.

[0239] The photovoltaic glass layer and backsheet are used to protect the solar cells, and they have the functions of sealing, insulation and waterproofing; the adhesive layer plays the role of bonding the photovoltaic glass layer to the solar cells and bonding the backsheet to the solar cells.

[0240] Optionally, the photovoltaic glass layer is made of tempered glass, the backsheet is made of TPT (polyvinyl fluoride) or TPE (thermoplastic elastomer), and the adhesive layer is made of EVA (polyethylene-polyvinyl acetate copolymer).

[0241] Furthermore, the aforementioned photovoltaic modules also include junction boxes and outer frames.

[0242] Junction boxes are used to protect the entire photovoltaic module's power generation system. They are essentially a current transfer station. When a cell short-circuits, the junction box will automatically disconnect the short-circuited cell string.

[0243] The outer frame serves to support and protect the entire photovoltaic module. The frame can be made of aluminum alloy, which has excellent strength and corrosion resistance.

[0244] Furthermore, silicone is used to bond and seal the connections between the frame and other parts of the photovoltaic module. The photovoltaic module can convert solar energy into electrical energy, which can then be stored in batteries or used to power loads.

[0245] In some embodiments, the photovoltaic module is a solar panel.

[0246] According to one embodiment of this application, a photovoltaic system is also provided, including the photovoltaic module described above.

[0247] The photovoltaic system utilizes the photovoltaic effect of the solar cells in the aforementioned photovoltaic modules to directly convert solar radiation energy into electrical energy with high efficiency; furthermore, the aforementioned photovoltaic system is a photovoltaic power generation system.

[0248] Photovoltaic modules are the core component of a photovoltaic power generation system. The aforementioned photovoltaic system includes one or more photovoltaic modules, which can be selected according to specific application scenarios. Furthermore, when the aforementioned photovoltaic system includes multiple photovoltaic modules, the multiple photovoltaic modules form a photovoltaic array.

[0249] The aforementioned photovoltaic system can be a stand-alone photovoltaic power generation system or a grid-connected photovoltaic power generation system.

[0250] An independent photovoltaic (PV) power generation system includes a PV array, battery bank, charge controller, power electronic converter (inverter), and load. Its working principle is that solar radiation energy is first converted into electrical energy by the PV array, then converted by the power electronic converter to supply power to the load. Simultaneously, excess electrical energy is stored as chemical energy in an energy storage device after passing through the charge controller. Thus, when sunlight is insufficient, the energy stored in the battery can be converted into 220V AC, 50Hz electrical energy through the power electronic inverter, filter, and power frequency transformer to supply AC loads.

[0251] A grid-connected photovoltaic (PV) power generation system includes a photovoltaic array, a high-frequency DC / DC boost circuit, a power electronic converter (inverter), and system monitoring. Its working principle is that solar radiation energy is converted by the photovoltaic array, then converted into high-voltage DC by a high-frequency DC converter, and finally inverted by the power electronic inverter to output a sinusoidal alternating current to the grid that is in phase with the grid voltage.

[0252] The two photovoltaic power generation systems mentioned above each have their own characteristics and can be selected according to the specific application scenario.

[0253] Other embodiments of this application provide an electrical device, including a solar cell as described above or a photovoltaic module as described above.

[0254] Other embodiments of this application provide a power generation device, including a solar cell as described above or a photovoltaic module as described above.

[0255] In some embodiments, the perovskite solar cell described above can be a power generation device that functions as an electrical device. The type of power generation device may include, but is not limited to, integrated power generation. The location of the power generation device may include, but is not limited to, the roof of a vehicle, the back panel, etc.

[0256] Furthermore, the aforementioned electrical devices may include mobile devices, such as electric vehicles, electric trains, ships and satellites, power generation systems, etc., but are not limited to these.

[0257] As another implementation method, the power supply device can be a wearable device, such as a watch.

[0258] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0259] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0260] I. Device Fabrication

[0261] The manufacturer of the dual nitrogen crosslinking agents of formula (11) and formula (12) used in the examples is Beijing Greenman Technology Co., Ltd.

[0262] Example 1

[0263] A method for fabricating a solar cell device is as follows:

[0264] 1) Preparation of FTO conductive glass (including the first electrode layer with substrate): A glass cleaning rack containing transparent glass was placed in an ultrasonic cleaner and cleaned for 20 min each with surfactant (2% Triton X-100 deionized water), deionized water, isopropanol, and anhydrous ethanol. Finally, it was dried in an oven at 70°C for 5 min. The transparent glass was then treated with a UV-O3 cleaner under a fume hood for 20 min and cooled to room temperature for later use.

[0265] 2) Preparation of the hole transport layer: SAM material (i.e., self-assembled monomolecular compounds, specific types are shown in Table 1) was weighed, and then a diazonium crosslinking agent (specific types are shown in Table 1) was added. The mixture was dispersed in a certain volume of DMSO solvent and shaken for 2 hours to completely dissolve the SAM material, forming a hole transport material precursor solution. The molar concentrations of SAM material and diazonium crosslinking agent were 0.001629 mol / mL and 0.001086 mol / mL, respectively. 150 μL of the hole transport material precursor solution was spin-coated at 4000 rpm / s for 25 seconds onto the conductive surface of an FTO transparent conductive glass. After spin-coating, the glass was placed on a hot plate and annealed at 100℃ for 10 minutes, then naturally cooled to room temperature to obtain a hole transport layer with a thickness of 1 nm.

[0266] 3) Preparation of the perovskite light-absorbing layer: 480.31 mg formamidinium hydroiodate (FAI), 31.39 mg methylammonium chloride (MAI), 6.38 mg methylammonium bromide (MABr), 38.97 mg cesium iodide (CsI), 22.57 mg lead bromide (PbBr2), and 1452.18 mg lead iodide (PbI2) were dissolved in 2 mL of a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (DMF to DMSO volume ratio of 4:1) to obtain a perovskite precursor solution. 150 μL of the perovskite precursor solution was spin-coated onto the hole transport layer at a rotation speed of 1000 rpm / s (20 s) + 5000 rpm / s (30 s) for 45 s. Ten s before the end of the spin-coating, 200 μL of chlorobenzene was rapidly added dropwise to regulate perovskite crystallization. After spin coating, the material was annealed at 150°C for 20 minutes to obtain a uniform, dense, smooth, and transparent perovskite light-absorbing layer (FA) with a thickness of 550 nm. 0.98 MA 0.02 ) 0.95 Cs 0.05 Pb(I 0.98 Br 0.02 )3).

[0267] 4) Fabrication of electron transport layer / hole blocking layer: Place the device obtained in step 3) into the evaporation device and place it in the evaporation machine to sequentially prepare a 30nm thick C60 layer and a 5nm thick BCP layer on the perovskite light-absorbing layer.

[0268] 5) Fabrication of the metal counter electrode (second electrode layer): On the BCP layer of the device obtained in step 4), a 140 nm thick layer of metallic copper (Cu) is deposited as the second electrode layer. Before deposition, a vacuum of 1.0 × 10⁻⁶ is first applied. -4Pa, then pre-deposited for 5 minutes. During the deposition process, when the copper thickness is in the 0-20 nm range, the Cu evaporation rate is approximately 0.1 A / s; when the copper thickness is in the 20 nm-140 nm range, the Cu evaporation rate is approximately 1 A / s.

[0269] Example 2

[0270] Example 2 is basically the same as Example 1, except that the hole transport layer is prepared differently, specifically the type of dual nitrogen crosslinking agent used, while the molar amount remains the same, as shown in Table 1.

[0271] Examples 3-5

[0272] Examples 3-5 are basically the same as Example 1, except that the hole transport layer is prepared differently, specifically the amount of the dual nitrogen crosslinking agent used is different (the volume of the solvent remains unchanged), which makes the molar ratio K of the hole transport material precursor liquid self-assembled monomolecular compound and the dual nitrogen crosslinking agent different, as shown in Table 1.

[0273] Comparative Example 1

[0274] It is basically the same as Example 1, except that, 2) the preparation of the hole transport layer is different. Specifically, the double nitrogen crosslinking agent is omitted from the hole transport layer material in Comparative Example 1.

[0275] Example 6

[0276] Example 6 is basically the same as Example 1, except that the hole transport layer is prepared differently, specifically the type of SAM material (i.e., self-assembled single-molecule compound) used, while the molar amount remains the same, as shown in Table 1.

[0277] Comparative Example 2

[0278] It is basically the same as Example 6, except that the preparation of the hole transport layer is different in 2). Specifically, the double nitrogen crosslinking agent is omitted in the hole transport layer of Comparative Example 1.

[0279] II. Photoelectric Performance Testing

[0280] Under sunlight and nitrogen protection, the cell was heated to 85°C and subjected to maximum power point tracking (MPPT) to test the photoelectric conversion efficiency (PCE) of the perovskite solar cell.

[0281] The specific operation is as follows. A 600*600mm long-life LED aging light source was used, and the light source intensity was calibrated to one sun. A hot plate was used to heat the battery. The fixture's built-in temperature and humidity acquisition module displayed a temperature of 85℃ and humidity <5%RH, at which point the MPPT tracking test began. The initial photoelectric conversion efficiency with an MPPT tracking time of 0 was obtained (as shown in Table 1), and the photoelectric conversion efficiency after 160 hours of MPPT tracking at 85℃ was also obtained. Furthermore, the efficiency retention rate after 160 hours of MPPT tracking at 85℃ was obtained, as shown in Table 1. The PCE curves for Example 2 and Comparative Example 1 from 0 to 160 hours of MPPT tracking time are shown in Table 1. Figure 2 Curves a and curve b are shown in the figure.

[0282] Among them, using an AAA-grade solar simulator under standard test conditions: incident light power of 100mW / cm² 2 The photoelectric performance parameters of the tested battery were measured using a spectral energy of AM1.5G, and the P values ​​were obtained. out P in V mpp J mpp V oc J sc Then, calculate the PCE based on the following formula:

[0283] PCE=P out / P in ;

[0284] =V oc ×J sc ×[(V mpp ×J mpp ) / (V oc ×J sc )] / P in ;

[0285] =V oc ×J sc ×FF / P in ;

[0286] Among them, P in P out V mpp J mpp V oc J sc FF represent: incident light power, operating output power of the battery under test, voltage at the maximum power point of the battery under test, current at the maximum power point of the battery under test, open circuit voltage, short circuit current, and fill factor, respectively.

[0287] The following table shows some parameters and performance results of the solar cells in each embodiment and comparative example. In the table, the molar ratio K represents the molar ratio of the self-assembled monomolecular compound and the dual-nitrogen crosslinking agent in the hole transport layer.

[0288] Table 1

[0289]

[0290] As can be seen from the comparison of the examples and comparative examples in the table above, Comparative Examples 1 and 2, which use a single uncrosslinked self-assembled monomolecular compound, have lower photoelectric conversion efficiency and efficiency retention. A comparison of Comparative Example 1 with Examples 1-5, and a comparison of Comparative Example 2 with Example 6, shows that this application, by using a dual-nitrogen crosslinking agent to crosslink the self-assembled monomolecular compound in the hole transport layer, can effectively improve the photoelectric conversion efficiency and efficiency retention of the solar cell, indicating an improvement in its photoelectric performance and stability.

[0291] As demonstrated in Examples 1-5, the solar cells fabricated using a molar ratio of self-assembled monomolecular compound and diazo crosslinking agent in the hole transport layer of this application (1-2):1 all exhibit good photoelectric conversion efficiency. Further controlling the molar ratio to (1.25-1.5):1 results in even better photoelectric conversion efficiency. Compared to Example 1, Example 2 demonstrates superior photoelectric conversion efficiency and efficiency retention because the diazo crosslinking agent is not replaced by fluorine. This facilitates the solution-based spreading of the perovskite light-absorbing layer on the hydrophilic hole transport layer surface, thereby improving the quality and photoelectric performance of the perovskite light-absorbing layer film.

[0292] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0293] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the scope of the claims.

Claims

1. A solar cell, characterized in that, The device includes a first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer. The perovskite light-absorbing layer is located between the first electrode layer and the second electrode layer. The hole transport layer is located between the first electrode layer and the perovskite light-absorbing layer. The hole transport layer includes a cross-linked compound, and the cross-linked compound has a structural unit (Ⅰ). （Ⅰ）； Wherein, * represents the linking site; Ar is the head group, R6 is the anchoring group, and L is the linking group that connects the head group Ar and the anchoring group R6; R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl; R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

2. The solar cell as described in claim 1, characterized in that, It has one or more of the following characteristics: (1) R1 and R3 each independently include halogen-substituted or unsubstituted C1~C10 alkyl groups; (2) R2 includes substituted or unsubstituted C1~C10 alkylene groups and substituted or unsubstituted C5~C30 aryl groups or substituted or unsubstituted heteroaryl groups connected to both ends of the substituted or unsubstituted C1~C10 alkylene groups.

3. The solar cell as described in claim 2, characterized in that, R2 has the following structure: ； Alternatively, R2 has the following structure: ； Where * represents a connection site; m is an integer from 1 to 10; R4 and R5 each independently include hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C5-C30 aryl or substituted or unsubstituted heteroaryl; optionally, R4 and R5 each independently include halogen-substituted or unsubstituted C1-C10 alkyl.

4. The solar cell according to any one of claims 1 to 3, characterized in that, It has one or more of the following characteristics: (1) The head group Ar includes substituted or unsubstituted C6~C30 aryl, substituted or unsubstituted C3~C30 heteroaryl or substituted or unsubstituted C6~C30 aromatic amino groups; (2) The linking group L includes one or more of a single bond, a substituted or unsubstituted C1~C10 alkylene group, an alkenyl group, a substituted or unsubstituted C5~C30 aryl group, or a substituted or unsubstituted heteroaryl group; (3) The anchoring group R6 includes an oxyacid group or its salt.

5. The solar cell as described in claim 4, characterized in that, It has one or more of the following characteristics: (1) In the head group Ar, the C6~C30 aryl group includes substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthraquinone, substituted or unsubstituted phenanthryl, substituted or unsubstituted alkyl or substituted or unsubstituted pyrene; (2) In the head group Ar, the C3~C30 heteroaryl group includes substituted or unsubstituted carbazole group, substituted or unsubstituted dibenzocarbazole group, substituted or unsubstituted dibenzopyridyl group or substituted or unsubstituted naphthalimide group; (3) In the head group Ar, the C6~C30 aromatic amino groups include substituted or unsubstituted triphenylamino groups; (4) The linking group L includes substituted or unsubstituted C1~C10 alkylene groups; (5) The anchoring group R6 includes one or more of the following: phosphonic acid group, phosphonic acid group, sulfonic acid group, sulfinic acid group, carboxylic acid group, boric acid group and silicate group and their salts.

6. The solar cell according to any one of claims 1 to 5, characterized in that, The cross-linked compound has structural unit (Ⅰ-1): ； Among them, R S1 The groups include one or more of H, C1-C30 alkyl, C1-C30 alkoxy, heterocyclic groups containing 3-20 cyclic atoms, aryl groups containing 5-20 cyclic atoms, heteroaryl groups containing 5-20 cyclic atoms, and halogens.

7. The solar cell as claimed in claim 6, characterized in that, The crosslinked compound has one or more of structural units (Ⅰ-11) and structural units (Ⅰ-12): （Ⅰ-11） （Ⅰ-12） Among them, R S1 The groups include one or more of the following: C1-C30 alkyl, C1-C30 alkoxy, heterocyclic group containing 3-20 cyclic atoms, aryl group containing 5-20 cyclic atoms, heteroaryl group containing 5-20 cyclic atoms, and halogen.

8. The solar cell according to any one of claims 1 to 7, characterized in that, It has one or more of the following characteristics: (1) The thickness of the hole transport layer is 0.1 nm to 10 nm; (2) The hole transport layer further includes a self-assembled monomolecular compound existing as a single molecule; optionally, the molar ratio of the self-assembled monomolecular compound existing as a single molecule in the hole transport layer to the self-assembled monomolecular compound contained in the crosslinking compound is ≤1:1, and may be further (0.25~0.5):

1.

9. A method for preparing a solar cell, characterized in that, Includes the following steps: A first electrode layer, a hole transport layer, a perovskite light-absorbing layer, and a second electrode layer are formed in a stacked configuration. The formation of the hole transport layer includes the following steps: The hole transport material precursor liquid is coated into a film and then cross-linked and cured to form the hole transport layer. The hole transport material precursor liquid comprises a self-assembled monomolecular compound and a dual nitrogen crosslinking agent; the self-assembled monomolecular compound comprises a head group Ar, an anchoring group R6, and a linking group L connecting the head group Ar and the anchoring group R6; The dual nitrogen crosslinking agent has the structure shown in formula (1): （1）， R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl; R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

10. The preparation method according to claim 9, characterized in that, The dual-nitrogen crosslinking agent has the structure shown in formula (1-a): （1-a）； Optionally, the dual nitrogen crosslinking agent has the structure shown in formula (1-a1): （1-a1）； Where m is an integer from 1 to 10; R4 and R5 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl; Optionally, R4 and R5 each independently include halogen-substituted or unsubstituted C1-C10 alkyl groups.

11. The preparation method according to claim 9 or 10, characterized in that, The self-assembled monomolecular compound includes one or more of 2PACz, 4PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, or Me-4PACz.

12. The preparation method according to any one of claims 9 to 11, characterized in that, It has one or more of the following characteristics: (1) In the hole transport material precursor solution, the molar ratio of the self-assembled monomolecular compound and the dual nitrogen crosslinking agent is (1~2):1, which can be (1.25~1.5):1; (2) In the hole transport material precursor solution, the molar concentration of the self-assembled monomolecular compound is 0.00065 mol / mL to 0.0065 mol / mL, and can be selected as 0.0009 mol / mL to 0.004 mol / mL; (3) The cross-linking curing is carried out under heating or light.

13. The preparation method according to claim 12, characterized in that, The heating temperature is 90℃~110℃, and / or the heating time is 10min~40min; The light source is ultraviolet light.

14. A precursor liquid for hole transport materials, characterized in that, Including self-assembled monomolecule compounds and dual-nitrogen crosslinking agents; The self-assembled monomolecular compound includes a head group Ar, an anchoring group R6, and a linking group L connecting the head group Ar and the anchoring group R6; The dual nitrogen crosslinking agent has the structure shown in formula (1): （1）， R1 and R3 each independently include hydrogen, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C5~C30 aryl or substituted or unsubstituted heteroaryl; R2 includes one or more combinations of substituted or unsubstituted C1-C10 alkylene groups, non-aromatic cycloalkyl groups, C2-C10 alkenyl groups, carbonyl groups, ester groups, substituted or unsubstituted C5-C30 aryl groups, or substituted and unsubstituted heteroaryl groups.

15. A hole transport layer, characterized in that, The hole transport layer is the hole transport layer as described in any one of claims 1 to 8, or the hole transport layer prepared using the hole transport material precursor liquid as described in claim 14.

16. A photovoltaic module, characterized in that, This includes the solar cell according to any one of claims 1 to 8 or the solar cell prepared by the preparation method according to any one of claims 9 to 13.

17. An electrical appliance, characterized in that, This includes the solar cell according to any one of claims 1 to 8, the solar cell prepared by the preparation method according to any one of claims 9 to 13, or the photovoltaic module according to claim 16.

18. A power generation device, characterized in that, This includes the solar cell according to any one of claims 1 to 8, the solar cell prepared by the preparation method according to any one of claims 9 to 13, or the photovoltaic module according to claim 16.

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