Perovskite solar cell, preparation method thereof and photovoltaic module

Abstract

The invention discloses a perovskite solar cell and a preparation method thereof, and a photovoltaic module, the perovskite solar cell comprises a substrate, a hole extraction layer, a perovskite layer, an electron transport layer and a first electrode which are sequentially laminated, the material of the hole extraction layer comprises R-2Ph-xPACz, and the structure of R-2Ph-xPACz is shown as a formula 1: # imgabs0 #, r is any one of CH3CH2O, CH3O, (CH3) 3C or a heterocyclic ring containing lone pair electrons, and x is 2-10. The R-2Ph-xPACz disclosed by the invention is relatively good in hole extraction and transmission effect and excellent in spreading uniformity, and the energy conversion efficiency of the solar cell can be further improved.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and in particular to a perovskite solar cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] In perovskite solar cells, the main function of the hole transport layer is to extract the holes generated in the perovskite layer and transfer them to the metal electrode. Therefore, the ability of the hole transport layer to extract holes has an important influence on the photoelectric conversion efficiency and performance stability of perovskite solar cells.

[0003] At present, the hole transport layer has a poor ability to extract holes, which limits the further improvement of the energy conversion efficiency of solar cells. Summary of the invention

[0004] In order to improve the ability of the hole transport layer to extract holes, the present invention discloses a perovskite solar cell and a preparation method thereof, and a photovoltaic module.

[0005] In a first aspect, an embodiment of the present invention provides a perovskite solar cell.

[0006] A perovskite solar cell comprises a substrate, a hole extraction layer, a perovskite layer, an electron transport layer and a first electrode which are stacked in sequence, wherein the material of the hole extraction layer comprises R-2Ph-xPACz, and the structure of the R-2Ph-xPACz is shown in Formula 1:

[0007] Wherein, R is any one of CH3CH2O, CH3O, (CH3)3C or a heterocycle containing a lone pair of electrons, and x is 2 to 10.

[0008] As an optional implementation, in an embodiment of the present invention, R is CH3O and x is 4.

[0009] As an optional implementation, in an embodiment of the present invention, the heterocycle containing a lone pair of electrons is one of thiophene or pyrrole.

[0010] The thickness of the hole extraction layer is 3nm to 15nm.

[0011] As an optional implementation, in an embodiment of the present invention, the substrate is a textured bottom cell and a composite layer stacked on the textured bottom cell, and the solar cell further includes a transparent conductive layer, and the transparent conductive layer is located on a side of the first electrode close to the substrate;

[0012] or,

[0013] The base is a glass substrate.

[0014] The material of the composite layer is a transparent conductive material; and / or the thickness of the composite layer is 15nm to 30nm; and / or the material of the transparent conductive layer is a transparent conductive material; and / or the thickness of the transparent conductive layer is 70nm to 110nm.

[0015] The perovskite solar cell further comprises a hole transport layer, which is stacked on the side of the hole extraction layer away from the perovskite layer. The material of the hole transport layer comprises Cu2O, CuO, MoO x , NiMgLiO or NiO x One or more combinations of .

[0016] The thickness of the hole transport layer is 10 nm to 20 nm.

[0017] The thickness of the perovskite layer is 600nm to 900nm; and / or the thickness of the electron transport layer is 10nm to 30nm; and / or the thickness of the first electrode is 250nm to 400nm.

[0018] In a second aspect, an embodiment of the present invention provides a method for preparing a perovskite solar cell.

[0019] A method for preparing a perovskite solar cell as described in the first aspect comprises the following steps:

[0020] Depositing the hole extraction layer comprising the R-2Ph-xPACz on the surface of the substrate;

[0021] The perovskite layer, the electron transport layer and the first electrode are sequentially prepared on the side of the hole extraction layer facing away from the substrate.

[0022] As an optional embodiment, in an embodiment of the present invention, the preparation method of R-2Ph-xPACz comprises the following steps:

[0023] The first compound of formula 2-1 is reacted with a dibromoalkyl group to generate a second compound of formula 2-2;

[0024] The second compound shown in formula 2-2 is reacted with triethyl phosphite, and then bromotrimethylsilane, methanol and water are added in sequence to react to generate the R-2Ph-xPACz;

[0025] Wherein, the structure of the first compound shown in Formula 2-1 is: The structure of the second compound shown in Formula 2-2 is:

[0026] As an optional implementation, in an embodiment of the present invention, in the step of synthesizing the second compound from the first compound, the first compound and the dibromoalkyl are first mixed, and then tetrabutylammonium bromide and an inorganic base aqueous solution are added, heated to 70° C. to 80° C. and stirred for 10 h to 14 h to obtain the second compound; and / or;

[0027] In the step of synthesizing the R-2Ph-xPACz from the second compound, the second compound is first mixed with triethyl phosphite, and then heated at 135°C to 150°C overnight to obtain a product precursor, the product precursor is purified, and then the purified product precursor is mixed with bromotrimethylsilane, reacted at 24°C to 28°C for 22h to 26h, the methanol is added, the reaction is carried out at 24°C to 28°C for 2.5h to 3.5h, the water is added, and the reaction is carried out at 24°C to 28°C for 100min to 140min to obtain the R-2Ph-xPACz.

[0028] As an optional embodiment, in an embodiment of the present invention, in the step of synthesizing the R-2Ph-xPACz from the second compound, the purification treatment of the product precursor includes the following steps:

[0029] Firstly, distill under reduced pressure to remove the solvent in the product precursor;

[0030] The product is then purified by column chromatography, wherein the eluent used for column chromatography purification is composed of dichloromethane and ethyl acetate in a volume ratio of (1.95-2.1):1.

[0031] As an optional embodiment, in an embodiment of the present invention, for every 1 mmol of the first compound, 5 mL to 6 mL of the dibromoalkyl is added; and / or,

[0032] For every 1.5 mmol of the second compound added, at least 52.49 mmol of triethyl phosphite, 11 mmol to 12 mmol of bromotrimethylsilane, 2 mL to 2.5 mL of methanol, and 15 mL to 16.5 mL of water are added.

[0033] As an optional embodiment, in an embodiment of the present invention, the R-2Ph-xPACz is deposited by slit coating, spin coating, spray coating, blade coating, inkjet printing or evaporation; and / or,

[0034] In the step of preparing the hole extraction layer, a R-2Ph-xPACz solution with a concentration of 1 mg / mL to 1.5 mg / mL is first prepared, and then the R-2Ph-xPACz solution is coated by spin coating at a speed of 3000 rpm to 5000 rpm for 30 s to 50 s.

[0035] As an optional implementation, in an embodiment of the present invention, the solvent of the R-2Ph-xPACz solution is one or a mixture of anhydrous ethanol, isopropanol or cyclohexane.

[0036] As an optional implementation, in an embodiment of the present invention, the method for preparing the perovskite layer comprises the following steps:

[0037] preparing a lead halide skeleton layer on the hole extraction layer;

[0038] A cationic solution is coated on the lead halide skeleton layer and annealed to obtain a perovskite layer.

[0039] As an optional implementation, in an embodiment of the present invention, the method for preparing the perovskite solar cell further includes: preparing a hole transport layer between the substrate and the hole extraction layer.

[0040] In a third aspect, an embodiment of the present invention provides a photovoltaic module.

[0041] A photovoltaic module comprises the perovskite solar cell as described in the first aspect or the perovskite solar cell prepared by the preparation method as described in the second aspect.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] In a perovskite solar cell provided by an embodiment of the present invention, in a hole extraction layer, the R group and the Ph group in R-2Ph-xPACz cooperate to synergistically increase the electron density, which is beneficial to the extraction of holes in the perovskite layer, thereby improving the extraction and transmission effects of holes, and through the cooperation of the R group and the Ph group, the overall spatial distortion range of the material is larger, which makes the intermolecular force of R-2Ph-xPACz significantly reduced, and the arrangement order and spreading uniformity of R-2Ph-xPACz are enhanced, which is beneficial to reducing the circuit resistance and improving the energy conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0045] Figure 1 It is a schematic diagram of the structure of the perovskite solar cell disclosed in an embodiment of the present invention.

[0046] Icons: 1. Substrate; 11. Texture-made bottom battery; 111. Second electrode; 12. Composite layer; 21. Hole transport layer; 22. Hole extraction layer; 3. Perovskite layer; 4. Passivation layer; 5. Electron transport layer; 6. Buffer layer; 7. Transparent conductive layer; 8. Anti-reflection layer; 9. First electrode. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In the present invention, the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0049] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0050] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0052] The technical solution of the present invention will be further described below in conjunction with embodiments and drawings.

[0053] First, refer to Figure 1 , an embodiment of the present invention provides a perovskite solar cell.

[0054] A perovskite solar cell comprises a substrate 1, a hole extraction layer 22, a perovskite layer 3, an electron transport layer 5 and a first electrode 9 which are stacked in sequence. The material of the hole extraction layer 22 comprises R-2Ph-xPACz. The structure of R-2Ph-xPACz is shown in Formula 1:

[0055] Wherein, R is CH3CH2O, CH3O, (CH3)3C or

[0056] Any of the heterocyclic rings having a lone pair of electrons, wherein x is 2-10.

[0057] The inventors experimentally found that compared with commonly used self-assembly materials such as 2PACz or MeO-2PACz, the combination of the R group and the Ph group in the above R-2Ph-xPACz can synergistically increase the electron density, which is beneficial to the extraction of holes in the perovskite layer 3, thereby improving the extraction and transmission of holes. Moreover, through the combination of the above R group and the Ph group, the overall spatial distortion range of the material is larger, which significantly reduces the intermolecular force of R-2Ph-xPACz, and enhances the arrangement order and spreading uniformity of R-2Ph-xPACz, which is beneficial to reducing the circuit resistance and improving the energy conversion efficiency of solar cells.

[0058] It should be noted that x represents the number of methylene groups between the carbazole group and the phosphate group in R-2Ph-xPACz, and x can be any value of 2, 4, 5, 6, 7 or 8.

[0059] Exemplarily, R-2Ph-xPACz may be:

[0060]

[0061] wait.

[0062] Furthermore, the hole extraction layer 22 may be a film layer containing only R-2Ph-xPACz, or a film layer containing R-2Ph-xPACz and other hole extraction materials. Preferably, the hole extraction layer may be formed by mixing a self-assembly material such as 2PACz, 4PACz or CH3O-2PACz with R-2Ph-xPACz.

[0063] In some embodiments, R is CH3O and x is 4.

[0064] When R is CH3O and x is 4, CH3O can provide a more compact electron cloud, with concentrated electron effect, which is more conducive to coordination with phenyl, increasing electron density, and facilitating better extraction of holes. In addition, the introduction of CH3O groups enhances the structural stability of CH3O-2Ph-4PACz, which is not easily oxidized or decomposed in a humid environment.

[0065] Combined with x being 4 and the moderate length of the methylene group, the intermolecular force of CH3O-2Ph-4PACz is low, it is not easy to aggregate, and it shows better solubility in good solvents such as ethanol and isopropanol, which makes the coating and dispersion performance of CH3O-2Ph-4PACz excellent. Using a small amount of CH3O-2Ph-4PACz can still show a better coverage effect on the surface of the substrate 1 with a planar structure or a velvet structure. Therefore, the thickness of the hole extraction layer 22 can be reduced by reducing the amount of CH3O-2Ph-4PACz, thereby better reducing the series resistance of the solar cell. In addition, the carbazole group and the phosphate group are in a more flexible position in the molecule, which is conducive to forming a good contact with the interface of the perovskite layer 3, which can further promote hole extraction.

[0066] It should be noted that the planar structure refers to a structure in which each layer of material in the solar cell is stacked in parallel in a certain order on a planar substrate 1. The process of preparing a solar cell on a substrate 1 with such a structure is relatively simple and the manufacturing process is relatively mature. The surface of the substrate 1 with a planar structure is relatively flat, such as the surface of glass or silicon wafer after polishing.

[0067] The velvet structure refers to a structure with a pyramid-like velvet surface formed after the surface of the substrate 1 is velveted. This structure can enhance the light trapping effect and improve the light absorption effect. The setting of the velvet structure is conducive to improving the energy conversion efficiency of solar cells. In perovskite silicon tandem solar cells, a velvet bottom cell 11 (such as a heterojunction bottom cell) with a velvet structure can be used as the substrate 1.

[0068] In some embodiments, the heterocyclic ring containing a lone pair of electrons is one of thiophene or pyrrole.

[0069] Thiophene is a strong π-electron donor, and the nitrogen atom with a lone pair of electrons in pyrrole participates in conjugation, making the electron cloud density on the pyrrole heterocyclic ring relatively large. Therefore, both thiophene and pyrrole can donate electrons to the benzene ring through the conjugation effect, increasing the electron density to facilitate hole extraction.

[0070] In some embodiments, the thickness of the hole extraction layer 22 is 3 nm to 15 nm.

[0071] The hole extraction layer 22 can show a better coverage effect on the substrate 1 within the above-mentioned thickness range, and the coverage effect of R-2Ph-xPACz is excellent, which makes the thickness of the hole extraction layer 22 within the range of 3nm to 15nm, which can not only take into account the coverage effect on the substrate 1, but also reduce the series resistance of the solar cell and improve the fill factor and open circuit voltage of the solar cell.

[0072] In some embodiments, the substrate 1 includes a textured bottom cell 11 and a composite layer 12 stacked on the textured bottom cell 11 . The solar cell further includes a transparent conductive layer 7 . The transparent conductive layer 7 is located on a side of the first electrode 9 close to the substrate 1 .

[0073] The surface of the textured bottom cell 11 has a velvet structure, and the film layers arranged on the textured bottom cell 11 all grow conformally along the velvet structure surface of the textured bottom cell 11, which can maintain the light trapping advantage of the velvet structure, while promoting the close integration of the film layer structure, improving the mechanical stability of the solar cell, and thus improving the overall performance of the solar cell.

[0074] In the present invention, the film layers above the substrate 1 together constitute the top battery, and the composite layer 12 serves as a physical connection layer between the textured bottom battery 11 and the top battery. The textured bottom battery 11 and the top battery are connected in series through the composite layer 12 to achieve effective current transmission.

[0075] The textured bottom cell 11 has a second electrode 111 corresponding to the first electrode 9. Both the first electrode 9 and the second electrode 111 are made of metal materials with good electrical conductivity, such as silver, copper or zinc. The first electrode 9 and the second electrode 111 are also used to collect photogenerated carriers, ensuring that the charges can be smoothly extracted from the inside of the solar cell, and promoting efficient operation of the solar cell.

[0076] The second electrode 111 may be deposited by evaporation. The thickness of the second electrode 111 is 300 nm to 500 nm. For example, the thickness of the second electrode 111 may be 300 nm, 320 nm, 350 nm, 360 nm, 390 nm, 420 nm, 480 nm or 500 nm.

[0077] In addition, in some embodiments, the base 1 may also be any substrate having a pyramid velvet structure, such as an ITO glass substrate.

[0078] In some embodiments, the material of the composite layer 12 is a transparent conductive material; and / or the thickness of the composite layer 12 is 15nm to 30nm; and / or the material of the transparent conductive layer 7 is a transparent conductive material; and / or the thickness of the transparent conductive layer 7 is 70nm to 110nm.

[0079] The transparent conductive material may be indium tin oxide, indium zinc oxide, etc. Exemplarily, the material of the composite layer 12 is indium tin oxide, and the transparent conductive layer 7 is indium zinc oxide.

[0080] For example, the thickness of the composite layer 12 may be 15 nm, 18 nm, 20 nm, 23 nm, 25 nm, 28 nm, or 30 nm.

[0081] Illustratively, the thickness of the transparent conductive layer 7 may be 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm or 110 nm, etc.

[0082] In some embodiments, the perovskite solar cell further comprises a hole transport layer 21, which is stacked on the hole extraction layer 22 on the side away from the perovskite layer 3, and the material of the hole transport layer 21 comprises Cu2O, CuO, MoO x , NiMgLiO or NiO x One or more combinations of .

[0083] The substrate 1 is a textured bottom battery 11 and a composite layer 12, Cu2O, CuO, MoO x , NiMgLiO or NiO x The metal oxides such as Cu2O, CuO, MoO have a better dispersion effect on the surface of the composite layer 12, and can be uniformly deposited on the surface of the composite layer 12 to form a hole transport layer 21 with better suede shape retention. x , NiMgLiO or NiO x The surface of the hole transport layer 21 formed by metal oxides such as R-2Ph-xPACz contains hydroxyl groups, and the surface of the hole transport layer 21 is easily anchored with the phosphate groups in R-2Ph-xPACz. In addition, R-2Ph-xPACz has excellent spreading uniformity and can be evenly self-assembled on the surface of the hole transport layer 21 to form a dense and uniform self-assembled molecular layer, so that the composite layer 12, the hole transport layer 21, and the hole extraction layer 22 can all obtain excellent suede retention effects, which are beneficial to improving the carrier transport effect after combination.

[0084] Preferably, the material of the hole transport layer 21 is NiO xThe suede surface of the composite layer 12, the hole transport layer 21, and the hole extraction layer 22 has a better shape retention effect and better carrier transport performance, which is conducive to better improving the energy conversion efficiency of solar cells.

[0085] In some embodiments, the thickness of the hole transport layer 21 is 10 nm to 20 nm.

[0086] For example, the thickness of the hole transport layer 21 may be 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc.

[0087] In some embodiments, the thickness of the perovskite layer 3 is 600 nm to 900 nm; and / or the thickness of the electron transport layer 5 is 10 nm to 30 nm; and / or the thickness of the first electrode 9 is 250 nm to 400 nm.

[0088] The textured surface of the hole extraction layer 22 has excellent shape-preserving effect, and provides a good growth substrate 1 for the subsequently grown perovskite layer 3 , which is beneficial to improving the textured surface shape-preserving effect and film-forming quality of the perovskite layer 3 .

[0089] Exemplarily, the thickness of the perovskite layer 3 can be 600nm, 630nm, 660nm, 700nm, 750nm, 800nm, 850nm and 900nm, etc., and the thickness of the lead halide skeleton layer can be 300nm, 330nm, 360nm, 400nm, 450nm, 500nm, 550nm and 600nm, etc.

[0090] For example, the thickness of the electron transport layer 5 may be 10 nm, 15 nm, 20 nm, 25 nm, 27 nm, 30 nm, etc.

[0091] By way of example, the thickness of the first electrode 9 may be 250 nm, 265 nm, 280 nm, 300 nm, 340 nm, 360 nm, 380 nm, 400 nm, etc.

[0092] In some embodiments, the solar cell further comprises a passivation layer 4, wherein the passivation layer 4 is stacked between the perovskite layer 3 and the electron transport layer 5; and / or,

[0093] The solar cell further includes a buffer layer 6, which is stacked between the electron transport layer 5 and the transparent conductive layer 7; and / or,

[0094] The solar cell further comprises an anti-reflection layer 8 , which is stacked and arranged on the side of the transparent conductive layer 7 facing away from the substrate 1 .

[0095] The material of the passivation layer 4 is LiF, and the thickness is 1 nm to 2 nm. By way of example, the thickness of the passivation layer 4 is 1 nm, 1.5 nm, 2 nm, and the like.

[0096] The material of the buffer layer 6 is SnO 2 , and the thickness is 10 nm to 30 nm. Exemplarily, the thickness of the buffer layer 6 is 10 nm, 15 nm, 20 nm, 25 nm, 27 nm and 30 nm.

[0097] The material of the anti-reflection layer 8 is LiF, and the thickness is 80 nm to 120 nm. Exemplarily, the thickness of the anti-reflection layer 8 is 80 nm, 90 nm, 95 nm, 100 nm, 103 nm, 109 nm, 116 nm, 120 nm, etc.

[0098] In a second aspect, an embodiment of the present invention provides a method for preparing a perovskite solar cell.

[0099] A method for preparing a perovskite solar cell as mentioned in the first aspect comprises the following steps:

[0100] Depositing a hole extraction layer 22 containing R-2Ph-xPACz on the surface of the substrate 1;

[0101] The perovskite layer 3 , the electron transport layer 5 and the first electrode 9 are sequentially prepared on the side of the hole extraction layer 22 facing away from the substrate 1 .

[0102] The R-2Ph-xPACz solution has good spreading uniformity. When the surface of the substrate 1 has a velvet structure, it can also be evenly attached to the surface of the substrate 1, and is not easy to accumulate at the bottom of the velvet structure. Therefore, the hole extraction layer 22 prepared from the R-2Ph-xPACz solution exhibits excellent shape retention effect.

[0103] The hole extraction layer 22 has an excellent shape-preserving effect, providing a good growth substrate 1 for the subsequently grown perovskite layer 3 and electron transport layer 5, thereby improving the performance of the solar cell.

[0104] Further, the preparation method of R-2Ph-xPACz comprises the following steps:

[0105] The first compound of formula 2-1 is reacted with a dibromoalkyl group to generate a second compound of formula 2-2;

[0106] The second compound shown in formula 2-2 is reacted with triethyl phosphite, and then bromotrimethylsilane, methanol and water are added in sequence to react to generate R-2Ph-xPACz;

[0107] Wherein, the structure of the first compound shown in Formula 2-1 is: The structure of the second compound shown in Formula 2-2 is:

[0108] The reaction formula for synthesizing the second compound represented by Formula 2-2 from the first compound represented by Formula 2-1 is as follows:

[0109]

[0110] The reaction formula for synthesizing R-2Ph-xPACz from the second compound is as follows:

[0111]

[0112] Specifically, in the step of synthesizing the second compound from the first compound, the first compound and the dibromoalkyl are first mixed, and then tetrabutylammonium bromide and an inorganic base aqueous solution are added, heated to 70° C. to 80° C. and stirred for 10 h to 14 h to obtain the second compound.

[0113] After the reaction of synthesizing the second compound is completed, a crude product containing the second compound is obtained. The purification method of the crude product comprises the following steps: extracting the second compound crude product with dichloromethane, then drying to remove moisture, removing the solvent under reduced pressure, and purifying by column chromatography to obtain the second compound. In the step of drying to remove moisture, the drying agent used is anhydrous sodium sulfate. In the column chromatography purification step, petroleum ether and dichloromethane with a volume ratio of 1:1 are used as eluents.

[0114] Preferably, for every 1 mmol of the first compound, 5 mL to 6 mL of the dibromoalkyl is added; further, the mass concentration of the inorganic base aqueous solution is 50%, and for every 1 mmol of the first compound, the volume of the inorganic base aqueous solution is 1.1 mL.

[0115] In the step of synthesizing R-2Ph-xPACz from the second compound, the second compound is first mixed with triethyl phosphite, and then heated at 135°C to 150°C overnight to obtain a product precursor, the product precursor is purified, and then the purified product precursor is mixed with bromotrimethylsilane, reacted at 24°C to 28°C for 22h to 26h, the methanol is added, the reaction is carried out at 24°C to 28°C for 2.5h to 3.5h, the water is added, and the reaction is carried out at 24°C to 28°C for 100min to 140min to obtain the R-2Ph-xPACz.

[0116] Further, the purification process of the product precursor comprises the following steps:

[0117] Firstly, distill under reduced pressure to remove the solvent in the product precursor;

[0118] The product is then purified by column chromatography, wherein the eluent used for column chromatography purification is composed of dichloromethane and ethyl acetate in a volume ratio of (1.95-2.1):1.

[0119] Preferably, the purified product precursor is a light yellow resin.

[0120] In the reaction process of synthesizing R-2Ph-xPACz, distilled water is preferably used and added dropwise. During the process of adding water, the reaction mixture gradually becomes opaque.

[0121] After the reaction of synthesizing R-2Ph-xPACz is completed, a crude product containing R-2Ph-xPACz is obtained. The purification method of the crude product comprises the following steps:

[0122] The solid product was filtered out, washed with water, and recrystallized in a mixed solvent of tetrahydrofuran and dichloromethane to obtain R-2Ph-xPACz.

[0123] In the process of recrystallization, the precipitated green powder is R-2Ph-xPACz. In the mixed solvent of tetrahydrofuran and dichloromethane, any ratio of tetrahydrofuran and dichloromethane can be selected, preferably tetrahydrofuran: dichloromethane is 1:2 to 2:1.

[0124] Furthermore, for every 1.5 mmol of the second compound added, at least 52.49 mmol of triethyl phosphite, 11 mmol to 12 mmol of bromotrimethylsilane, 2 mL to 2.5 mL of methanol, and 15 mL to 16.5 mL of water are added.

[0125] More preferably, the input amount of triethyl phosphite is 52.49 mmol to 54 mmol.

[0126] In some embodiments, R-2Ph-xPACz is deposited by slit coating, spin coating, spray coating, doctor blading, inkjet printing or evaporation.

[0127] Illustratively, when depositing R-2Ph-xPACz by coating, R-2Ph-xPACz is first placed in a solution environment, and then a solution containing R-2Ph-xPACz is deposited on the surface of the substrate by slit coating, scraping, spin coating or spraying to form a R-2Ph-xPACz wet film layer, and then annealing is performed to evaporate the solvent in the R-2Ph-xPACz wet film layer to obtain a corresponding hole extraction layer 22.

[0128] In some embodiments, in the step of preparing the hole extraction layer 22, a R-2Ph-xPACz solution with a concentration of 1 mg / mL to 1.5 mg / mL is first prepared, and then the R-2Ph-xPACz solution is applied by spin coating at a speed of 3000 rpm to 5000 rpm for 30 s to 50 s.

[0129] By controlling the concentration of R-2Ph-xPACz and the spin coating parameters, a hole extraction layer 22 with better thickness and film uniformity can be prepared, thereby further optimizing the performance of the solar cell.

[0130] In some embodiments, the solvent of the R-2Ph-xPACz solution is one or a mixture of anhydrous ethanol, isopropanol or cyclohexane.

[0131] Anhydrous ethanol, isopropanol or cyclohexane has good solubility for R-2Ph-xPACz, which helps to evenly disperse R-2Ph-xPACz, thereby facilitating the formation of high-quality uniform thin films and improving the performance of solar cells. In addition, anhydrous ethanol, isopropanol or cyclohexane has good volatility and can be quickly removed during the process of thin film formation, reducing solvent residues, and helping to improve the quality of the hole extraction layer 22 and the stability of the solar cell.

[0132] In some embodiments, the method for preparing the perovskite layer 3 comprises the following steps:

[0133] Preparing a lead halide skeleton layer on the hole extraction layer 22;

[0134] A cationic solution is coated on the lead halide skeleton layer and annealed to obtain a perovskite layer 3.

[0135] The perovskite layer 3 prepared by the above method has excellent shape-preserving effect and is suitable for use on the surface of a film layer with a velvet structure. In addition, there is a relatively strong interaction between R-2Ph-xPACz and lead halide, which can guide the lead halide skeleton layer to grow highly conformally on the surface of the hole extraction layer 22, and further improve the shape-preserving effect of the perovskite layer 3 after the reaction between the cationic solution and the lead halide skeleton layer.

[0136] Furthermore, the lead halide skeleton layer is composed of lead iodide and cesium halide, wherein the mass ratio of lead iodide to cesium halide is 5 to 10:1, and the cesium halide is any one of cesium bromide, cesium chloride or cesium iodide. Preferably, the cesium halide is cesium bromide.

[0137] Further, the cationic solution can be coated on the lead halide skeleton layer by spin coating, spray coating, blade coating or slit coating. The cationic solution is composed of one or more of FAI, FABr, MACl, and MABr. Preferably, the cationic solution is composed of FAI, FABr, MACl, and MABr in a mass ratio of 50:14:10:8.

[0138] In some embodiments, the method for preparing a perovskite solar cell further includes: preparing a hole transport layer 21 between the substrate 1 and the hole extraction layer 22 .

[0139] In a third aspect, an embodiment of the present invention provides a photovoltaic module.

[0140] A photovoltaic module comprises the perovskite solar cell as mentioned in the first aspect or the perovskite solar cell prepared by the preparation method as mentioned in the second aspect.

[0141] The technical solution of the present invention will be further described below in conjunction with embodiments and drawings.

[0142] Embodiment 1

[0143] An embodiment of the present invention provides a solar cell, comprising:

[0144] Heterojunction bottom cell;

[0145] The composite layer is stacked on the surface of the heterojunction bottom cell, the material of the composite layer is indium tin oxide, and the thickness is 30nm;

[0146] The hole transport layer is stacked on the side of the composite layer away from the heterojunction bottom battery. The material of the hole transport layer is NiO x , thickness is 15nm;

[0147] The hole extraction layer is stacked on the hole transport layer away from the heterojunction bottom battery side, the material of the first transport layer is CH3O-2Ph-4PACz, the structure of CH3O-2Ph-4PACz is shown in Formula 1-1, and the thickness is 6nm;

[0148] The perovskite layer is stacked on the side of the hole extraction layer away from the heterojunction bottom cell, the perovskite layer is formed by the reaction of the lead iodide skeleton layer and the cationic solution, the thickness of the lead iodide skeleton layer is 450nm, and the thickness of the perovskite layer is 700nm;

[0149] The passivation layer is stacked on the side of the perovskite layer away from the heterojunction bottom cell. The material of the passivation layer is LiF and the thickness is 1.5nm.

[0150] The electron transport layer is stacked on the side of the passivation layer away from the heterojunction bottom battery. The material of the electron transport layer is C 60 , thickness is 20nm;

[0151] The buffer layer is stacked on the side of the electron transport layer away from the heterojunction bottom battery, and the material of the buffer layer is SnO2 with a thickness of 15nm;

[0152] A transparent conductive layer is stacked on the side of the buffer layer away from the heterojunction bottom cell, the transparent conductive layer is indium zinc oxide, and the thickness is 100nm;

[0153] An anti-reflection layer is stacked on the side of the transparent conductive layer away from the heterojunction bottom cell, the anti-reflection layer is made of LiF and has a thickness of 100nm;

[0154] A first electrode passes through the anti-reflection layer and forms an ohmic contact with the transparent conductive layer. The material of the first electrode is Ag and the height is 300 nm.

[0155] The preparation method of the solar cell comprises the following steps:

[0156] Preparation of CH3O-2Ph-4PACz:

[0157] Compound 1 (2 mmol) was dissolved in 1,4-dibromobutane (10 mL), and tetrabutylammonium bromide (0.16 g, 0.5 mmol) and 50% KOH aqueous solution (1.1 ml, 20 mmol) were added, followed by heating to 70°C and stirring overnight; after the reaction was completed, the mixture was extracted with dichloromethane, wherein the organic layer was dried over anhydrous Na2SO4 and the solvent was removed under reduced pressure, and the crude product was purified by column chromatography using petroleum ether and dichloromethane in a volume ratio of 1:1 as eluent to obtain a white crystalline solid, namely compound 2;

[0158] Compound 2 (1.5 mmol) was dissolved in triethyl phosphite (10 ml, 52.49 mmol) and heated at 140°C overnight; the solvent was removed under reduced pressure, and the crude product was purified by column chromatography using dichloromethane and ethyl acetate in a volume ratio of 1:2 as eluent to obtain a light yellow resin; under an argon atmosphere, the light yellow resin was dissolved in anhydrous 1,4-dioxane (15 mL), and bromotrimethylsilane (1.5 ml, 11 mmol) was added dropwise, and stirred for 22 h under an argon atmosphere at 25°C, followed by the addition of methanol (2 mL) and continued stirring for 3 h, and finally distilled water (15 ml) was added dropwise until the solution became opaque, and after stirring for another 2 h, the product was filtered out, washed with water, and recrystallized in a mixed solvent of tetrahydrofuran and dichloromethane to obtain a green powder, namely MeO-2Ph-4PACz.

[0159] Preparation of solar cells:

[0160] Provide heterojunction bottom cells;

[0161] The composite layer was prepared by magnetron sputtering on the heterojunction bottom cell;

[0162] A hole transport layer is prepared on the composite layer by using a physical vapor deposition method;

[0163] The hole extraction layer is prepared by solution spin coating on the hole transport layer, as follows:

[0164] Take 0.2 mL of 1.3 mg / mL CH3O-2Ph-4PACz isopropanol solution, spin-coat the CH3O-2Ph-4PACz solution on the surface of the hole transport layer at a rotation speed of 4000 rpm for 30 seconds, and then anneal at 100°C for 10 minutes to obtain a hole extraction layer;

[0165] The perovskite layer was prepared on the hole extraction layer using a two-step method as follows:

[0166] Co-evaporating lead iodide and cesium bromide on the surface of the hole extraction layer, with the evaporation rate ratio of lead iodide to cesium bromide being 5:1, to obtain a lead iodide skeleton layer;

[0167] A cationic solution was spin-coated on the lead iodide skeleton layer. The cationic solution was prepared by dissolving FAI, FABr, MACl, and MABr in 1 mL of isopropanol in a mass ratio of 50:14:10:8, and annealed at 150° C. for 20 min to obtain a perovskite layer.

[0168] A passivation layer is prepared on the perovskite layer by an evaporation method;

[0169] An electron transport layer is prepared on the passivation layer by using an evaporation method;

[0170] A buffer layer is prepared on the electron transport layer by atomic layer deposition;

[0171] A transparent conductive layer is prepared on the buffer layer by using a magnetron sputtering method;

[0172] An anti-reflection layer is prepared on the transparent conductive layer by using an evaporation method;

[0173] The first electrode is prepared by an evaporation method.

[0174] Comparative Example 1

[0175] The comparative example of the present invention provides a solar cell, which is different from the first embodiment in that CH3O-2Ph-4PACz is replaced by CH3O-4PACz, the CAS number of CH3O-4PACz is 2922526-56-3, and the structure is shown in Formula 1-5:

[0176]

[0177] The rest is consistent with the first embodiment.

[0178] Comparative Example 2

[0179] The comparative example of the present invention provides a solar cell, which is different from the first embodiment in that CH3O-2PACz is used to replace CH3O-2Ph-4PACz, the CAS number of CH3O-2PACz is 2377770-18-6, and the structure is shown in Formula 1-6:

[0180]

[0181] The rest is consistent with the first embodiment.

[0182] Comparative Example 3

[0183] The comparative example of the present invention provides a solar cell, which is different from the first embodiment in that 2Ph-4PACz is used to replace CH3O-2Ph-4PACz, the CAS number of 2Ph-4PACz is 2814500-04-2, and the structure is shown in Formula 1-7:

[0184]

[0185] The rest is consistent with the first embodiment.

[0186] experiment

[0187] Solar cell performance test

[0188] Wavelabs solar simulator is used to test the performance of perovskite tandem solar cells. Test conditions: AM1.5, 1000W / m 2 , the test environment temperature is 25℃. Before the test, the sunlight intensity simulated by the light source is calibrated using a standard silicon cell. The performance test is energy conversion efficiency in %, open circuit voltage in V, and short circuit current in mA / cm 2 , filling factor, in %.

[0189] The test results of the above embodiments and comparative examples are shown in Table 1.

[0190] Table 1

[0191]

[0192] By comparing the data of Example 1 with Comparative Examples 1, 2 and 3 in Table 1, it can be seen that by introducing a phenyl group and combining it with a specific group on the carbazole group, the electron density can be better synergistically increased, the hole extraction ability can be improved, and the intermolecular force can be reduced, thereby improving the uniformity of the hole extraction layer, thereby improving the energy conversion efficiency of the solar cell.

[0193] The perovskite solar cell and its preparation method, and the photovoltaic module disclosed in the embodiments of the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the perovskite solar cell and its preparation method, photovoltaic module and its core concept of the present invention; at the same time, for ordinary technicians in this field, according to the concept of the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A perovskite solar cell, characterized in that: The invention comprises a substrate, a hole extraction layer, a perovskite layer, an electron transport layer and a first electrode which are stacked in sequence, wherein the material of the hole extraction layer comprises R-2Ph-xPACz, and the structure of R-2Ph-xPACz is shown in Formula 1: Wherein, R is any one of CH3CH2O, CH3O, (CH3)3C or a heterocycle containing a lone pair of electrons, and x is 2 to 10.

2. The perovskite solar cell according to claim 1, characterized in that: The R is CH3O, and the x is 4.

3. The perovskite solar cell according to claim 1, characterized in that: The heterocycle containing a lone pair of electrons is one of thiophene or pyrrole.

4. The perovskite solar cell according to claim 1, characterized in that: The thickness of the hole extraction layer is 3nm to 15nm.

5. The perovskite solar cell according to any one of claims 1 to 4, characterized in that: The substrate is a textured bottom cell and a composite layer stacked on the textured bottom cell, and the solar cell further includes a transparent conductive layer, which is located on the side of the first electrode close to the substrate; or, The base is a glass substrate.

6. The perovskite solar cell according to claim 5, characterized in that: The material of the composite layer is a transparent conductive material; and / or the thickness of the composite layer is 15nm to 30nm; and / or the material of the transparent conductive layer is a transparent conductive material; and / or the thickness of the transparent conductive layer is 70nm to 110nm.

7. The perovskite solar cell according to any one of claims 1 to 4, characterized in that: The perovskite solar cell further comprises a hole transport layer, which is stacked on the side of the hole extraction layer away from the perovskite layer. The material of the hole transport layer comprises Cu2O, CuO, MoO x , NiMgLiO or NiO x One or more combinations of .

8. The perovskite solar cell according to claim 7, characterized in that: The thickness of the hole transport layer is 10 nm to 20 nm.

9. The perovskite solar cell according to any one of claims 1 to 4, characterized in that: The thickness of the perovskite layer is 600 nm to 900 nm; and / or the thickness of the electron transport layer is 10 nm to 30 nm; and / or the thickness of the first electrode is 250 nm to 400 nm.

10. A method for preparing a perovskite solar cell, characterized in that: The method for preparing a perovskite solar cell according to any one of claims 1 to 9 comprises the following steps: Depositing the hole extraction layer comprising the R-2Ph-xPACz on the surface of the substrate; The perovskite layer, the electron transport layer and the first electrode are sequentially prepared on the side of the hole extraction layer facing away from the substrate.

11. The method for preparing a perovskite solar cell according to claim 10, characterized in that: The preparation method of R-2Ph-xPACz comprises the following steps: The first compound of formula 2-1 is reacted with a dibromoalkyl group to generate a second compound of formula 2-2; The second compound shown in formula 2-2 is reacted with triethyl phosphite, and then bromotrimethylsilane, methanol and water are added in sequence to react to generate the R-2Ph-xPACz; Wherein, the structure of the first compound shown in Formula 2-1 is: The structure of the second compound shown in Formula 2-2 is:

12. The method for preparing a perovskite solar cell according to claim 11, characterized in that: In the step of synthesizing the second compound from the first compound, the first compound and the dibromoalkyl are first mixed, tetrabutylammonium bromide and an inorganic base aqueous solution are added, heated to 70° C. to 80° C. and stirred for 10 h to 14 h to obtain the second compound; and / or, In the step of synthesizing the R-2Ph-xPACz from the second compound, the second compound is first mixed with triethyl phosphite, and then heated at 135°C to 150°C overnight to obtain a product precursor, the product precursor is purified, and then the purified product precursor is mixed with bromotrimethylsilane, reacted at 24°C to 28°C for 22h to 26h, the methanol is added, the reaction is carried out at 24°C to 28°C for 2.5h to 3.5h, the water is added, and the reaction is carried out at 24°C to 28°C for 100min to 140min to obtain the R-2Ph-xPACz.

13. The method for preparing a perovskite solar cell according to claim 12, characterized in that: In the step of synthesizing the R-2Ph-xPACz from the second compound, the purification treatment of the product precursor comprises the following steps: Firstly, distill under reduced pressure to remove the solvent in the product precursor; The product is then purified by column chromatography, wherein the eluent used for column chromatography purification is composed of dichloromethane and ethyl acetate in a volume ratio of (1.95-2.1):

1.

14. The method for preparing a perovskite solar cell according to claim 11, characterized in that: For every 1 mmol of the first compound, 5 mL to 6 mL of the dibromoalkyl group is added; and / or, For every 1.5 mmol of the second compound added, at least 52.49 mmol of triethyl phosphite, 11 mmol to 12 mmol of bromotrimethylsilane, 2 mL to 2.5 mL of methanol, and 15 mL to 16.5 mL of water are added.

15. The method for preparing a perovskite solar cell according to claim 10, characterized in that: The R-2Ph-xPACz is deposited by slit coating, spin coating, spray coating, doctor blade coating, inkjet printing or evaporation; and / or, In the step of preparing the hole extraction layer, a R-2Ph-xPACz solution with a concentration of 1 mg / mL to 1.5 mg / mL is first prepared, and then the R-2Ph-xPACz solution is coated by spin coating at a speed of 3000 rpm to 5000 rpm for 30 s to 50 s.

16. The method for preparing a perovskite solar cell according to claim 15, characterized in that: The solvent of the R-2Ph-xPACz solution is one or a mixture of anhydrous ethanol, isopropanol or cyclohexane.

17. The method for preparing a perovskite solar cell according to claim 10 or 11, characterized in that: The method for preparing the perovskite layer comprises the following steps: preparing a lead halide skeleton layer on the hole extraction layer; A cationic solution is coated on the lead halide skeleton layer and annealed to obtain a perovskite layer.

18. The method for preparing a perovskite solar cell according to claim 10 or 11, characterized in that: The method for preparing the perovskite solar cell further includes: preparing a hole transport layer between the substrate and the hole extraction layer.

19. A photovoltaic module, characterized in that: It includes the perovskite solar cell as described in any one of claims 1 to 9 or the perovskite solar cell prepared by the preparation method as described in any one of claims 10 to 18.

Images