Perovskite solar cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the field of solar cells, in particular to a perovskite solar cell, a preparation method and a photovoltaic module. The perovskite solar cell comprises a metal oxide layer; the self-assembled monomolecular layer is arranged on the surface of one side of the metal oxide layer, and self-assembled molecules in the self-assembled monomolecular layer have any one structure of formulas (1)-(3) as shown in the specification; formula (2); formula (3); wherein R and R'are respectively and independently selected from any one of-CH2-,-CH2CH2-or-CH2CH2CH2-. The perovskite solar cell has the self-assembled monomolecular layer with more uniform distribution, the defects of the self-assembled monomolecular layer are improved, the problems of carrier transport mismatch, energy level mismatch and carrier recombination are reduced, and the photoelectric property of the perovskite solar cell is improved.

Description

TECHNICAL FIELD

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

[0002] In the perovskite solar cell, the interaction between the self-assembled molecules in the self-assembled monolayer and the metal oxide layer is poor, and part of the self-assembled molecules is easy to fall off from the metal oxide layer, resulting in uneven distribution of the self-assembled molecules in the self-assembled monolayer, so that the film layer has local defects, causing problems such as carrier transport mismatch, energy level mismatch and carrier recombination aggravation, which affects the photoelectric performance of the perovskite solar cell. SUMMARY

[0003] The present application discloses a perovskite solar cell, a preparation method thereof and a photovoltaic module, to solve the problems of carrier transport mismatch, energy level mismatch and carrier recombination aggravation caused by local defects of the self-assembled monolayer.

[0004] In order to achieve the above-mentioned purpose, in a first aspect, the present application discloses a perovskite solar cell, comprising: a metal oxide layer; a self-assembled monolayer, the self-assembled monolayer is arranged on one side surface of the metal oxide layer, and the self-assembled molecules in the self-assembled monolayer have any one of structures as formula (1) to formula (3): formula (1); formula (2); formula (3); wherein, the R and the R' are each independently selected from any one of -CH2-, -CH2CH2- or -CH2CH2CH2-.

[0005] Further, the self-assembled molecules have the structure of formula (1).

[0006] Further, the R and the R' are of the same kind.

[0007] Further, the R and the R' are both -CH2CH2-.

[0008] Further, the self-assembled monolayer is further provided with a perovskite layer on the surface away from the metal oxide layer, and the perovskite layer contains at least one of PbI2, PbBr2, PbCl2 and PbF2. 2+

[0009] Further, the perovskite solar cell is a perovskite laminated solar cell, comprising: ​a bottom cell, and a first transport layer, a perovskite layer, a second transport layer and a first electrode which are sequentially stacked on a surface of the bottom cell; wherein one of the first transport layer and the second transport layer is a hole transport layer, and the other is an electron transport layer; a second electrode disposed on a surface of the bottom cell away from the first transport layer, the first electrode and the second electrode being one positive electrode and the other negative electrode; wherein when the metal oxide layer is the hole transport layer, the self-assembled monolayer is disposed between the hole transport layer and the perovskite layer; or, when the metal oxide layer is the electron transport layer, the self-assembled monolayer is disposed between the electron transport layer and the perovskite layer; or, the perovskite solar cell further comprises an electron-hole recombination layer disposed between the bottom cell and the first transport layer, when the metal oxide layer is the hole transport layer, the self-assembled monolayer is disposed between the hole transport layer and the perovskite layer; when the metal oxide layer is the electron transport layer, the self-assembled monolayer is disposed between the electron transport layer and the perovskite layer; when the metal oxide layer is the electron-hole recombination layer and the self-assembled monolayer is the hole transport layer, the self-assembled monolayer is disposed between the electron-hole recombination layer and the perovskite layer.

[0010] Further, the bottom cell comprises any one of a heterojunction cell, a passivated contact cell, a copper indium gallium selenide cell, and an organic cell; The material of the hole transport layer comprises nickel oxide, and the thickness of the hole transport layer is 20-25 nm. The material of the electron transport layer comprises any one of C60 or tin oxide, and the thickness of the electron transport layer is 20-25 nm. The thickness of the self-assembled monolayer is less than 2 nm. The thickness of the perovskite layer is 400-500 nm, and the material of the perovskite layer has a general chemical formula ABX3, wherein A is an A-site cation, B is a B-site cation, and X is an X-site anion; the A-site cation comprises at least one of FA + , MA + or Cs + ; and / or, the B-site cation comprises at least one of Pb 2+ ; and / or, the X-site anion comprises at least one of I - , F - , Br - , Cl - or SCN - . The electron-hole recombination layer comprises one or more of indium tin oxide, indium zinc oxide or indium tungsten oxide, and the thickness of the electron-hole recombination layer is 10-15 nm.

[0011] Further, the perovskite solar cell is a perovskite single-junction cell, which comprises: a glass substrate, and a transparent conductive substrate, a first transport layer, a perovskite layer, a second transport layer, a transparent conductive layer and a first electrode which are sequentially stacked on the surface of the glass substrate; one of the first transport layer and the second transport layer is the hole transport layer, and the other is the electron transport layer; a second electrode, which is disposed on a different region of the same side surface of the transparent conductive substrate as the first transport layer, and one of the first electrode and the second electrode is the positive electrode, and the other is the negative electrode; wherein, when the metal oxide layer is the hole transport layer, the self-assembled monolayer is disposed between the hole transport layer and the perovskite layer; or, when the metal oxide layer is the electron transport layer, the self-assembled monolayer is disposed between the electron transport layer and the perovskite layer.

[0012] In a second aspect, the present application provides a preparation method of a perovskite solar cell, the perovskite solar cell being the perovskite solar cell of the first aspect, and the preparation method comprising the following steps: preparing a self-assembled monolayer on the metal oxide layer; the self-assembled molecules in the self-assembled monolayer have any one of structures as shown in formula (1)-(3): formula (1); formula (2); formula (3); wherein, the R and the R' are each independently selected from any one of -CH2-, -CH2CH2- or -CH2CH2CH2-.

[0013] Further, the solution comprises the self-assembled molecules and a solvent, and the solvent is at least one of ethanol or isopropanol; the coating step is to spin-coat the solution on the metal oxide layer at a rotation speed of 3500-4000 rpm; the relative humidity of the annealing is 5-10%; the concentration of the solution is 0.5-2.0 mg / mL. ​

[0014] Further, the concentration of the solution is 0.9 mg / mL-1.1 mg / mL.

[0015] In a third aspect, the present application provides a photovoltaic module, which comprises the solar cell according to the first aspect, or the solar cell prepared by the preparation method according to the second aspect.

[0016] Compared with the prior art, the present application has the following beneficial effects: In the solar cell provided by the present application, the steric hindrance of the self-assembled molecule used in the self-assembled monolayer is small, and the coverage of the self-assembled molecule on the metal oxide layer is higher, and the self-assembled molecule comprises a bipyridine and two phosphonic acid groups respectively located on two pyridine rings of the bipyridine, and the conjugated structure of the bipyridine improves the carrier transport effect; more importantly, the phosphonic acid groups can form coordination bonds with the metal of the metal oxide layer, and the number of the phosphonic acid groups of the self-assembled molecule is more, the number of the coordination bonds is increased, the force between the self-assembled monolayer and the metal oxide layer is improved, the possibility of the self-assembled monolayer falling off is reduced, the distribution of the self-assembled monolayer in the plane perpendicular to the thickness direction of the perovskite solar cell is more uniform, the defects of the self-assembled monolayer are improved, and the problems of carrier transport mismatch, energy level mismatch and carrier recombination are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0018] Figures 1-6 are structure schematic diagrams of six perovskite tandem solar cells provided by embodiments of the present application, respectively; Figures 7-8 are structure schematic diagrams of two perovskite single-junction solar cells provided by embodiments of the present application, respectively.

[0019] Explanation of reference signs: 1, self-assembled monolayer; 2, bottom cell; 3, hole transport layer; 4, electron transport layer; 41, buffer layer; 5, perovskite layer; 51, passivation layer; 61, first electrode; 62, second electrode; 7, electron-hole recombination layer; 8, glass substrate; 81, transparent conductive substrate; 9, transparent conductive layer; 91, antireflection layer. DETAILED DESCRIPTION

[0020] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0021] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0022] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meaning of these terms in the present application can be understood according to the specific situation.

[0023] In addition, the terms "mount", "set", "provided with", "connect", "connect" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific situation.

[0024] In addition, the terms "first", "second", and the like are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, the meaning of "multiple" is two or more.

[0025] The technical solutions provided by the present application will be further described below in conjunction with the embodiments and drawings.

[0026] As shown in Figures 1-8 The present application provides a perovskite solar cell, which comprises: a metal oxide layer; Self-assembled monolayer 1, which is disposed on one side surface of a metal oxide layer, wherein the self-assembled molecules in self-assembled monolayer 1 have any one of the structures of formula (1) to formula (3): Equation (1); Equation (2); Equation (3); Wherein, R and R' are each independently selected from -CH2-, -CH2CH2-, or -CH2CH2CH2-. In perovskite solar cells, the hole transport layer, electron transport layer, or electron-hole recombination layer can be made of metal oxide materials. Therefore, the metal oxide layer in the embodiments of this application can be any one of hole transport layer 3, electron transport layer 4, or electron-hole recombination layer 7.

[0027] For example, the self-assembled molecule can have any of the structural formulas (1-1) to (1-4), (2-1), or (3-1). When R is -CH2- and R' is -CH2CH2CH2-, the self-assembled molecule has the structure shown in formula (1-2). When R is -CH2CH2- and R' is -CH2-, the self-assembled molecule has the structure shown in formula (1-3).

[0028]

[0029] In this embodiment, the self-assembled molecule used in the self-assembled monolayer 1 has low steric hindrance and higher coverage on the metal oxide layer. The self-assembled molecule includes bipyridine and two phosphonic acid groups located on the two pyridine rings in the bipyridine. The conjugated structure of bipyridine improves the carrier transport effect. More importantly, the phosphonic acid groups can form coordination bonds with the metal of the metal oxide layer. The self-assembled molecule has more phosphonic acid groups, which increases the number of coordination bonds. The interaction force between the self-assembled monomolecule and the metal oxide layer is enhanced, reducing the possibility of self-assembled monomolecule detachment. This makes its distribution on the plane perpendicular to the thickness direction of the perovskite solar cell more uniform, improves the defects of the self-assembled monolayer 1, and reduces the problems of carrier transport mismatch, energy level mismatch, and carrier recombination.

[0030] Preferably, the self-assembled molecule has a structure of formula (1), in which the phosphonic acid group is located at the para position of N, so that the atomic spacing on the N heterocycle is increased, the spatial distribution is more dispersed, and the mutual distance is relatively farther, so that the spatial repulsion between the substituents is the weakest, the steric hindrance of the self-assembled monomer of the structure is smaller, the agglomeration of the self-assembled molecule can be alleviated, the coverage effect of the self-assembled molecule on the metal oxide layer is improved, more self-assembled monomers of the self-assembled monolayer 1 are distributed more uniformly, the defects of the self-assembled monolayer 1 are better improved, the carrier transport and energy level matching effects are improved, and the problem of carrier recombination is reduced.

[0031] Further, R and R' are the same kind, when R and R' on the two pyridine rings of the bipyridine are the same group, the symmetry of the self-assembled molecule is improved, the agglomeration phenomenon is reduced, and the uniformity of the self-assembled monolayer 1 is improved.

[0032] For example, when R and R' are both -CH2-, the self-assembled molecule can have any one of structures of formula (1-1), formula (2-1), or formula (3-1), and when R and R' are both -CH2CH2-, the self-assembled molecule has a structure of formula (1-4).

[0033] Preferably, R and R' are both -CH2CH2-. When R and R' on the two pyridine rings of the bipyridine are the same group, the symmetry of the self-assembled molecule is improved, the agglomeration phenomenon is reduced, and the uniformity of the self-assembled monolayer 1 is improved. When R and R' are both -CH2CH2-, the overall effect of the steric hindrance of the self-assembled molecule and the negative charge distribution of the phosphonic acid group is better, which is more conducive to the transport of carriers.

[0034] Further, the self-assembled monolayer 1 further comprises a perovskite layer 5 on the surface away from the metal oxide layer, and the perovskite layer 5 comprises at least one of Pb 2+ .

[0035] In the embodiment of the present application, the phosphonic acid group and the nitrogen heterocycle of the bipyridine of the self-assembled monomer in the self-assembled monolayer 1 can form a coordination bond with the uncoordinated Pb 2+ , Ga 2+ or Sn 2+ in the perovskite layer 5, the defects of the contact surface between the perovskite layer 5 and the self-assembled monolayer 1 are reduced, the non-radiative recombination is reduced, and the photoelectric conversion efficiency of the perovskite solar cell is further improved.

[0036] Further, the perovskite solar cell is a perovskite stacked solar cell, and the perovskite stacked solar cell comprises: The bottom cell 2, and the first transport layer, the perovskite layer 5, the second transport layer and the first electrode 61 are sequentially stacked on the surface of the bottom cell 2; wherein one of the first transport layer and the second transport layer is a hole transport layer 3, and the other is an electron transport layer 4.

[0037] The second electrode 62 is arranged on the surface of the bottom cell 2 away from the first transport layer, and the first electrode 61 and the second electrode 62 are one positive electrode and the other negative electrode.

[0038] In an alternative embodiment, the metal oxide layer is a hole transport layer 3, and the self-assembled monolayer 1 is arranged between the hole transport layer 3 and the perovskite layer 5, and when the perovskite solar cell is a p-i-n structure, the structure is as shown in Figure 1 The perovskite cell can also be an n-i-p structure.

[0039] In an alternative embodiment, the metal oxide layer is an electron transport layer 4, and the self-assembled monolayer 1 is arranged between the electron transport layer 4 and the perovskite layer 5, and when the perovskite solar cell is an n-i-p structure, the structure is as shown in Figure 2 The perovskite cell can also be a p-i-n structure.

[0040] The bottom cell 2 includes any one of a heterojunction cell, a passivated contact cell, a copper indium gallium selenide cell, and an organic cell.

[0041] The material of the hole transport layer 3 includes nickel oxide, and the thickness of the hole transport layer 3 is 20 nm to 25 nm.

[0042] Exemplarily, the thickness of the hole transport layer 3 is 20 nm, 21 nm, 22 nm, 23 nm, 24 nm or 25 nm. Preferably, the thickness of the hole transport layer 3 is 20 nm.

[0043] The material of the electron transport layer 4 includes any one of C60 or tin oxide, and the thickness of the electron transport layer 4 is 20 nm to 25 nm.

[0044] Exemplarily, the thickness of the electron transport layer 4 is 20 nm, 21 nm, 22 nm, 23 nm, 24 nm or 25 nm. Preferably, the thickness of the electron transport layer 4 is 20 nm. When the metal oxide layer is an electron transport layer 4, the material of the electron transport layer 4 is tin oxide.

[0045] The thickness of the self-assembled monolayer 1 is less than 2 nm.

[0046] The perovskite layer 5 has a thickness of 400 nm to 500 nm, and the material of the perovskite layer 5 has a general chemical formula ABX3, wherein A is an A-site cation, B is a B-site cation, and X is an X-site anion; the A-site cation includes at least one of FA + , MA + , Cs + , K + , Ca 2+ , Zn 2+ , Na + , Rb + , DMA + , BA + , PA + , AA + , BMIM + , EA + , or EDA 2+ ; and / or, the B-site cation includes at least one of Pb 2+ ; and / or, the X-site anion includes at least one of I - , F - , Br - , Cl - , SCN - , OCN - , BF4 - , TFSI - , CF3 - , CF3CO2 - , COO - , or SO3 - .

[0047] Exemplarily, the perovskite layer 5 has a thickness of 400 nm, 420 nm, 450 nm, 470 nm, 490 nm, or 500 nm.

[0048] The material of the first electrode 61 and the second electrode 62 is one or a combination of gold, silver, copper, and aluminum, and preferably, silver is selected as the electrode material; the thickness of the first electrode 61 is 200 nm to 300 nm, and the thickness of the second electrode 62 is 150 nm to 250 nm.

[0049] Exemplarily, the thickness of the first electrode 61 is 200 nm, 220 nm, 230 nm, 245 nm, 270 nm, 290 nm, or 300 nm. Preferably, the thickness of the first electrode 61 is 300 nm.

[0050] Exemplarily, the thickness of the second electrode 62 is 150 nm, 170 nm, 185 nm, 200 nm, 215 nm, 230 nm or 250 nm. Preferably, the thickness of the first electrode 61 is 250 nm.

[0051] In the embodiment of the present application, the self-assembled monolayer 1 arranged between the metal oxide layer and the perovskite layer 5 contains phosphonic acid groups. On the one hand, the phosphonic acid groups form coordination bonds with the metal of the hole transport layer 3, so that the interaction force between the self-assembled monolayer 1 and the metal oxide layer is improved, the defects of the self-assembled monolayer 1 are improved, and the problems of carrier transport mismatch and carrier recombination are reduced. On the other hand, the phosphonic acid groups form coordination bonds with uncoordinated Pb 2+ , Ga 2+ or Sn 2+ in the perovskite layer 5, which improves the defects of the contact surface between the perovskite layer 5 and the self-assembled monolayer 1. In addition, the self-assembled monolayer 1 can further improve the energy level matching effect between the metal oxide layer and the perovskite layer 5. Under the combined action of the above three aspects, the photoelectric conversion efficiency of the perovskite solar cell is improved.

[0052] Further, as shown in Figures 3-6 , the perovskite solar cell further comprises an electron-hole recombination layer 7 arranged between the bottom cell 2 and the first transport layer. The electron-hole recombination layer 7 comprises one or more of indium tin oxide, indium zinc oxide or indium tungsten oxide, and the thickness of the electron-hole recombination layer 7 is 10 nm to 15 nm.

[0053] Exemplarily, the thickness of the electron-hole recombination layer 7 is 10 nm, 11 nm, 12 nm, 13 nm, 14 nm or 15 nm. Preferably, the thickness of the electron-hole transport layer 7 is 10 nm.

[0054] Optionally, when the metal oxide layer is a hole transport layer 3, the self-assembled monolayer 1 is arranged between the hole transport layer 3 and the perovskite layer 5, and the perovskite solar cell is a p-i-n structure, as shown in Figure 3 . The perovskite cell can also be an n-i-p structure.

[0055] Optionally, when the metal oxide layer is an electron transport layer 4, the self-assembled monolayer 1 is arranged between the electron transport layer 4 and the perovskite layer 5, and the perovskite solar cell is an n-i-p structure, as shown in Figure 4 . The perovskite cell can also be a p-i-n structure.

[0056] Optionally, the metal oxide layer is the electron-hole recombination layer 7, the self-assembled monolayer 1 is the hole transport layer 3, the self-assembled monolayer 1 is arranged between the electron-hole recombination layer 7 and the perovskite layer 5, and the structure of the perovskite solar cell is as shown in Figure 5 In the embodiment of the present application, the self-assembled monolayer 1 as the hole transport layer 3 can improve the energy level matching effect of the electron-hole transport layer 3 and the perovskite layer 5.

[0057] Further, other functional layers can also be included in the structure of the perovskite solar cell, for example, the perovskite solar cell with the p-i-n structure with the electron-hole recombination layer 7 and the metal oxide layer as the hole transport layer 3, as shown in Figure 6 The other functional layers include: A transparent conductive layer 9 is arranged on the surface of the electron transport layer 4 away from the perovskite layer 5; the material of the transparent conductive layer 9 includes one or more of indium tin oxide, indium zinc oxide or indium tungsten oxide, and the thickness of the transparent conductive layer 9 is 100 nm to 120 nm.

[0058] Exemplarily, the thickness of the transparent conductive layer 9 is 100 nm, 105 nm, 110 nm, 115 nm or 120 nm. Preferably, the thickness of the transparent conductive layer 9 is 100 nm.

[0059] A passivation layer 51 is arranged between the perovskite layer 5 and the electron transport layer 4, the material of the passivation layer 51 includes LiF or two-dimensional perovskite material, and the thickness of the passivation layer 51 is 1 nm to 2 nm.

[0060] Exemplarily, the thickness of the passivation layer 51 is 1 nm or 2 nm. Preferably, the thickness of the passivation layer 51 is 1 nm.

[0061] A buffer layer 41 is arranged on the surface of the electron transport layer 4, the material of the buffer layer 41 is tin oxide or LiF, and the thickness of the buffer layer 41 is 15 nm to 20 nm.

[0062] Exemplarily, the thickness of the buffer layer 41 is 15 nm, 16 nm, 17 nm, 18 nm, 19 nm or 20 nm. Preferably, the thickness of the buffer layer 41 is 20 nm.

[0063] An anti-reflection layer 91 is arranged on the surface of the transparent conductive layer 9, the material of the anti-reflection layer 91 is LiF or MgF2, and the thickness of the anti-reflection layer 91 is 150 nm to 180 nm.

[0064] Exemplarily, the thickness of the anti-reflection layer 91 is 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm or 180 nm. Preferably, the thickness of the anti-reflection layer 91 is 150 nm.

[0065] As another alternative embodiment, the perovskite solar cell is a perovskite single-junction cell, such as Figures 7-8 As shown, the perovskite single-junction cell comprises: a glass substrate 8, and a transparent conductive substrate 81, a first transport layer, a perovskite layer 5, a second transport layer, a transparent conductive layer 9 and a first electrode 61, which are sequentially arranged on a surface of the glass substrate 8; one of the first transport layer and the second transport layer is a hole transport layer 3, and the other is an electron transport layer 4; a second electrode 62, the second electrode 62 and the first transport layer are arranged on different regions of a same surface of the transparent conductive substrate 81, and the first electrode 61 and the second electrode 62 are one anode and the other cathode; Optionally, when the metal oxide layer is the hole transport layer 3, a self-assembled monolayer 1 is arranged between the hole transport layer 3 and the perovskite layer 5, and the structure is as shown in Figure 7 Optionally, when the metal oxide layer is the electron transport layer 4, a self-assembled monolayer 1 is arranged between the electron transport layer 4 and the perovskite layer 5, and the structure is as shown in

[0066] Optionally, when the metal oxide layer is the electron transport layer 4, a self-assembled monolayer 1 is arranged between the electron transport layer 4 and the perovskite layer 5, and the structure is as shown in Figure 8

[0067] In the embodiment, the self-assembled monolayer 1 arranged between the metal oxide layer and the perovskite layer 5 contains phosphonic acid groups and is uniformly distributed, the carrier transport mismatch and carrier recombination of the perovskite solar cell are improved, and on the other hand, the phosphonic acid groups can also improve the defects of the contact surface between the perovskite layer 5 and the self-assembled monolayer 1.

[0068] The embodiment also provides a preparation method of the perovskite solar cell. It can be understood that the preparation method is one method for obtaining the embodiment, but is not limited to the only method. That is, the perovskite solar cell of the embodiment can also be prepared by other methods, and the embodiment does not limit this, so it should not be understood as the preparation method provided by the embodiment is a limitation on the perovskite solar cell.

[0069] The preparation method comprises the following steps: preparing a self-assembled monolayer 1 on the metal oxide layer; The self-assembled molecules in the self-assembled monolayer 1 have any one of structures as shown in formula (1) to formula (3): Formula (1); Formula (2); Formula (3); ​wherein R and R' are each independently selected from any one of -CH2-, -CH2CH2- or -CH2CH2CH2-.

[0070] Further, the step of preparing the self-assembled monolayer 1 on the metal oxide layer comprises: applying a solution containing self-assembled molecules on the metal oxide layer; annealing at 100-110℃ for 10-15 min to obtain the self-assembled monolayer 1.

[0071] Exemplarily, the annealing temperature can be 100℃, 102℃, 104℃, 107℃, 109℃ or 110℃. Preferably, the annealing temperature is 100℃.

[0072] Exemplarily, the annealing time can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min. Preferably, the annealing time is 10 min.

[0073] wherein the solution comprises self-assembled molecules and a solvent, the solvent is at least one of ethanol or isopropanol, and the concentration of the solution is 0.5-2.0 mg / mL.

[0074] Exemplarily, the concentration of the solution is 0.5 mg / mL, 0.9 mg / mL, 1.2 mg / mL, 1.5 mg / mL, 1.8 mg / mL or 2.0 mg / mL. Preferably, the concentration of the solution is 0.9-1.1 mg / mL. When the concentration of the self-assembled molecule solution is within the preferred concentration range, both the effect of the self-assembled monolayer 1 and the aggregation of the self-assembled molecules in the solution can be reduced, so that the self-assembled monolayer 1 can better transport carriers and match energy levels, and the problem of carrier recombination can be reduced.

[0075] wherein the applying step is spin coating the solution on the metal oxide layer at a rotation speed of 3500-4000 rpm.

[0076] Exemplarily, the rotation speed of the applying step is 3500 rpm, 3600 rpm, 3700 rpm, 3800 rpm, 3900 rpm or 4000 rpm. Preferably, the rotation speed of the applying step is 4000 rpm.

[0077] Preferably, the annealing temperature is 100℃ and the time is 10 min.

[0078] wherein the relative humidity of the annealing is 5-10%.

[0079] Exemplarily, the relative humidity of the annealing can be 5%, 6%, 7%, 8%, 9% or 10%. Preferably, the relative humidity of the annealing is 5%.

[0080] The embodiment of the present application also provides a photovoltaic module. The photovoltaic module comprises the perovskite solar cell and the preparation method of the perovskite solar cell.

[0081] The technical solution of the present application will be further explained in combination with more specific embodiments and experimental test results.

[0082] Embodiment 1 The embodiment provides a perovskite solar cell, and a preparation method of the perovskite solar cell comprises the following steps: Step 1, configuring a solution containing self-assembled monomers 4,4-bis-methyl phosphonic acid-2,2-dipyridine is dissolved in ethanol, and a homogenizer is used to shake at 800 rpm for 30 min at room temperature to obtain a solution containing self-assembled monomers, and the concentration of the solution is 1.0 mg / mL.

[0083] Step 2, activating a bottom cell A commercial textured silicon substrate with a thickness of 150 μm is heated on a heating table at 150℃ for 15 min.

[0084] Step 3, preparing a hole transport layer A rotating target containing 99.99% of nickel oxide is used to obtain a nickel oxide layer with a thickness of 20 nm under the conditions of 0.52 Pa, Ar:O2=700:5 and 2-4 reciprocating movements of the carrier plate.

[0085] Step 4, preparing a self-assembled monolayer The solution containing self-assembled monomers is spin-coated onto the nickel oxide layer at a speed of 4000 rpm, the spin-coating time is 30 s, and the acceleration is 2000 rpm / s. Then, the self-assembled monolayer is obtained by annealing at 100℃ for 10 min under a relative humidity of 5%.

[0086] Step 5, preparing a perovskite layer PbI2 and CsBr are co-evaporated on the self-assembled monolayer to prepare a lead skeleton.

[0087] 300 mg of FAI, 70 mg of MABr and 40 mg of MACl are dissolved in 5 mL of ethanol to obtain a cation solution, and the cation solution is spin-coated on the lead skeleton, the relative humidity of the spin-coating is 5%, the spin-coating speed is 4000 rpm, the acceleration is 4000 rpm / s, the spin-coating time is 30 s, and then the perovskite layer with a thickness of 450 nm is obtained by annealing at 135℃ for 30 min.

[0088] Step 6, preparation of passivation layer and electron transport layer 200 mg of LiF and C60 were weighed into metal evaporation boat 1 and metal evaporation boat 2, respectively, and sequentially evaporated at a rate of <0.5 Å / s to obtain a 1 nm thick LiF layer and a 25 nm thick C60 film layer.

[0089] Step 7, preparation of buffer layer A tin oxide layer was deposited on the electron transport layer at a process temperature of 70-90°C for a process time of 30-45 min and a thickness of 15 nm.

[0090] Step 8, preparation of transparent conductive layer A transparent conductive layer was magnetron sputtered on the buffer layer to obtain an ITO layer with a thickness of 100 nm.

[0091] Step 9, preparation of electrode The first electrode and the second electrode were evaporated to a thickness of 300 nm and 250 nm, respectively.

[0092] Step 10, preparation of antireflection layer A LiF layer with a thickness of 100 nm was evaporated.

[0093] Example 2 The difference between this example and Example 1 is that the self-assembled molecule is 4,4-bisethylphosphonic acid-2,2-bipyridine.

[0094] Example 3 The difference between this example and Example 1 is that the self-assembled molecule is 4,4-bispropylphosphonic acid-2,2-bipyridine.

[0095] Example 4 The difference between this example and Example 1 is that the self-assembled molecule has a structure as shown in formula (2-1).

[0096] Example 5 The difference between this example and Example 1 is that the self-assembled molecule has a structure as shown in formula (3-1).

[0097] Example 6 The difference between this example and Example 1 is that the concentration of the solution is 0.5 mg / mL.

[0098] Example 7 The difference between this example and Example 1 is that the concentration of the solution is 1.5 mg / mL.

[0099] Example 8 The difference between this example and Example 1 is only that the concentration of the solution is 2.0 mg / mL.

[0100] Comparative Example 1 The difference between this example and Example 1 is only that the self-assembled monolayer is not provided.

[0101] Comparative Example 2 The difference between this example and Example 1 is only that the self-assembled molecule is 2PACz.

[0102] Comparative Example 3 The difference between this example and Example 1 is only that the self-assembled molecule is MeO-2PACz.

[0103] Comparative Example 4 The difference between this example and Example 1 is only that the self-assembled molecule is Me-4PACz.

[0104] Photoelectric performance test The perovskite tandem solar cells of Examples 1-8 and Comparative Examples 1-4 are tested for open-circuit voltage, fill factor, photoelectric conversion efficiency, etc. using a halm test sorting device. The halm machine is a device for simulating sunlight, and is equipped with an electronic load, data acquisition and calculation devices for testing the electrical performance of photovoltaic devices (including solar cells). The calibrated light intensity of the tested solar cells is controlled to be 1000±5 W / m².

[0105] The photoelectric performance test results of Examples 1-8 and Comparative Examples 1-4 are shown in Table 1.

[0106] Table 1 Photoelectric performance test results of Examples 1-8 and Comparative Examples 1-4

[0107] As can be seen from the data in Table 1, the photoelectric conversion efficiency of Examples 1-8 is improved compared with Comparative Examples 1-4. The steric hindrance of the self-assembled molecule used in the self-assembled monolayer in Examples 1-8 is small, and its coverage on the metal oxide layer is higher. Moreover, the self-assembled molecule includes bipyridine and two phosphonic acid groups respectively located on the two pyridine rings of the bipyridine, and the conjugated structure of the bipyridine improves the carrier transport effect. More importantly, the phosphonic acid groups can form coordination bonds with the metal of the metal oxide layer, and the number of phosphonic acid groups of the self-assembled molecule is larger, increasing the number of coordination bonds, improving the force between the self-assembled monolayer and the metal oxide layer, reducing the possibility of the self-assembled monolayer falling off, making the distribution of the self-assembled monolayer more uniform in the plane perpendicular to the thickness direction of the perovskite solar cell, improving the defects of the self-assembled monolayer, and reducing the problems of carrier transport mismatch, energy level mismatch, and carrier recombination.

[0108] In Embodiments 1-3, R and R' of Embodiment 2 are -CH2CH2-, the overall effect of the steric hindrance of the self-assembled molecule and the negative charge distribution of the phosphonic acid group is better, and the carrier transmission is more favorable. Compared with Embodiments 4-5, the phosphonic acid group in the self-assembled molecule structure of Embodiment 1 is located at the para position of N, so that the atomic spacing on the N heterocycle is increased, the spatial distribution is more dispersed, the mutual distance is relatively farther, the steric hindrance of the self-assembled monomer of the structure is smaller, the agglomeration of the self-assembled molecule can be relieved, the covering effect of the self-assembled molecule on the metal oxide layer is improved, the self-assembled monolayer has more self-assembled monomers and the distribution is more uniform, the defects of the self-assembled monolayer are better improved, the carrier transmission and energy level matching effect are improved, and the problem of carrier recombination is reduced. Compared with Embodiments 6-8, the solution concentration for preparing the self-assembled monolayer of Embodiment 1 is in the preferred range, which can ensure the effect of the self-assembled monolayer and reduce the agglomeration of the self-assembled molecule in the solution, so that the self-assembled monolayer can better transport carriers and match energy levels, and the problem of carrier recombination is reduced.

[0109] The technical solutions disclosed in the embodiments of the present application are described in detail above, and specific examples are applied in this paper to describe the principles and implementation modes of the present application. The above description of the embodiments is only used to help understand the technical solutions and core invention points of the embodiments of the present application. At the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed, and the above description of the embodiments should not be understood as a limitation of the present application.

Claims

1. A perovskite solar cell, characterized by, The perovskite solar cell comprises: a metal oxide layer; a self-assembled monolayer, the self-assembled monolayer is arranged on one side surface of the metal oxide layer, the self-assembled molecules in the self-assembled monolayer have any one structure of formula (1)~formula (3): Formula (1); Formula (2); Formula (3); wherein, the R and the R' are each independently selected from any one of -CH2-, -CH2CH2- or -CH2CH2CH2-.

2. The perovskite solar cell according to claim 1, characterized in that, The self-assembled molecules have the structure of formula (1).

3. The perovskite solar cell according to claim 2, characterized in that, The R and the R' are the same kind.

4. The perovskite solar cell according to claim 3, characterized in that, The R and the R' are both -CH2CH2-. 5.The perovskite solar cell of claim 1, wherein, The self-assembled monolayer is further provided with a perovskite layer on the surface facing away from the metal oxide layer, the perovskite layer comprising Pb 2+ at least one of the group consisting of Sn, Ge, and Se.

6. The perovskite solar cell according to any one of claims 1-5, characterized in that, The perovskite solar cell is a perovskite tandem solar cell, the perovskite tandem solar cell comprises: a bottom cell, and a first transport layer, a perovskite layer, a second transport layer and a first electrode which are sequentially stacked on the surface of the bottom cell; wherein one of the first transport layer and the second transport layer is a hole transport layer, and the other is an electron transport layer; a second electrode, the second electrode is arranged on the surface of the bottom cell away from the first transport layer, and one of the first electrode and the second electrode is a positive electrode, and the other is a negative electrode; wherein, when the metal oxide layer is the hole transport layer, the self-assembled monolayer is arranged between the hole transport layer and the perovskite layer; or, when the metal oxide layer is the electron transport layer, the self-assembled monolayer is arranged between the electron transport layer and the perovskite layer; or, The perovskite solar cell further comprises an electron-hole recombination layer, the electron-hole recombination layer is arranged between the bottom cell and the first transport layer, the self-assembled monolayer is arranged between the hole transport layer and the perovskite layer when the metal oxide layer is the hole transport layer, the self-assembled monolayer is arranged between the electron transport layer and the perovskite layer when the metal oxide layer is the electron transport layer, and the self-assembled monolayer is arranged between the electron-hole recombination layer and the perovskite layer when the metal oxide layer is the electron-hole recombination layer and the self-assembled monolayer is the hole transport layer.

7. The perovskite solar cell according to claim 6, characterized in that, The bottom cell comprises any one of a heterojunction cell, a passivated contact cell, a copper indium gallium selenide cell, and an organic cell; The material of the hole transport layer comprises nickel oxide, and the thickness of the hole transport layer is 20 nm~25 nm; The material of the electron transport layer comprises any one of C60 or tin oxide, and the thickness of the electron transport layer is 20 nm~25 nm; The thickness of the self-assembled monolayer is less than 2 nm; The perovskite layer has a thickness of 400 nm to 500 nm, and a material of the perovskite layer has a chemical general formula ABX3, wherein the A is an A-site cation, the B is a B-site cation, and the X is an X-site anion; the A-site cation includes at least one of FA + , MA + , or Cs + ; and / or, the B-site cation includes at least one of Pb 2+ ; and / or, the X-site anion includes at least one of I - , F - , Br - , Cl - , or SCN - . The electron-hole recombination layer comprises one or more of indium tin oxide, indium zinc oxide or indium tungsten oxide, and the thickness of the electron-hole recombination layer is 10 nm~15 nm.

8. The perovskite solar cell according to any one of claims 1-5, characterized in that, The perovskite solar cell is a perovskite single-junction cell, the perovskite single-junction cell comprises: a glass substrate, and a transparent conductive substrate, a first transport layer, a perovskite layer, a second transport layer, a transparent conductive layer and a first electrode which are sequentially stacked on the surface of the glass substrate; one of the first transport layer and the second transport layer is the hole transport layer, and the other is the electron transport layer; a second electrode, the second electrode and the first transport layer being disposed on different regions of the same side surface of the transparent conductive substrate, the first electrode and the second electrode being one positive electrode and the other negative electrode; wherein, when the metal oxide layer is the hole transport layer, the self-assembled monolayer is disposed between the hole transport layer and the perovskite layer; or, when the metal oxide layer is the electron transport layer, the self-assembled monolayer is disposed between the electron transport layer and the perovskite layer.

9. A method of manufacturing a perovskite solar cell, characterized by, The preparation method comprises: preparing a self-assembled monolayer on a metal oxide layer; the self-assembled molecules in the self-assembled monolayer have any one of structures as in formula (1)~formula (3): Formula (1); Equation (2); Equation (3); wherein, the R and the R' are each independently selected from any one of -CH2-, -CH2CH2- or -CH2CH2CH2-.

10. The method of claim 9, wherein, The step of preparing a self-assembled monolayer on a metal oxide layer comprises: applying a solution containing the self-assembled molecules on the metal oxide layer; annealing at 100℃~110℃ for 10 min~15 min to obtain the self-assembled monolayer.

11. The method of claim 10, wherein, The solution comprises the self-assembled molecules and a solvent, the solvent being at least one of ethanol or isopropanol; The applying step is spin coating the solution on the metal oxide layer at a rotation speed of 3500 rpm~4000 rpm; The relative humidity of the annealing is 5%~10%; The concentration of the solution is 0.5 mg / mL~2.0 mg / mL.

12. The method of making according to any one of claim 11, wherein, The concentration of the solution is 0.9 mg / mL~1.1 mg / mL.

13. A photovoltaic module, characterized by The photovoltaic module comprises the perovskite solar cell as in any one of claims 1-8 and the preparation method as in any one of claims 9-12.

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