Interlayer structure for solar cell and preparation method and application thereof

Abstract

The invention provides an intermediate layer structure for a solar cell and a preparation method and application thereof. The intermediate layer structure comprises a transparent conductive oxide layer, a self-assembled monomolecular hole transport layer and a self-assembled monomolecular connecting layer for connecting the transparent conductive oxide layer and the self-assembled monomolecular hole transport layer, the material of the self-assembled monomolecular hole transport layer is a self-assembled monomolecular material with a phosphonic acid end group; the material of the self-assembled monomolecular connecting layer is selected from one or two of a silane self-assembled monomolecular layer material or a carboxylic acid self-assembled monomolecular layer material, and the silane self-assembled monomolecular layer material and the carboxylic acid self-assembled monomolecular layer material have sulfydryl groups; the problems that in the prior art, the material coverage rate of a self-assembled monomolecular hole transport layer on a TCO is low, and the material distribution of the self-assembled monomolecular hole transport layer is not uniform are solved.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and in particular to an intermediate layer structure for solar cells, a preparation method thereof and an application thereof. Background Art

[0002] At present, the photoelectric conversion efficiency (PCE) of single-cell perovskite solar cells (PSCs) has reached 25.7%, which is very close to its SQ theoretical limit. In order to break through the SQ limit of this single-cell solar cell, constructing multi-cell tandem solar cells (TSCs) can make more efficient use of solar energy. Tandem solar cells are a promising way to achieve high-performance photovoltaic power generation at low cost. At present, the highest efficiency of perovskite / crystalline silicon tandem solar cells has reached 33.9%, far exceeding the Shockley-Queisser limit (29.4%) of traditional silicon-based solar cells, and has great commercial potential. Whether it is a single-cell solar cell or a multi-cell tandem solar cell, PSCs based on self-assembled monolayer materials as hole transport layers (HTL) show excellent performance. The HTL prepared based on self-assembled monolayer materials has the advantages of easy adjustment of energy level alignment with the perovskite light absorption layer and small parasitic absorption. However, in the prior art, HTL prepared based on self-assembled monolayer materials often exhibits poor uniformity on transparent conductive oxides (TCO), resulting in low coverage of self-assembled monolayer materials on TCO and uneven distribution of self-assembled monolayer materials, which limits the improvement of battery performance. Summary of the invention

[0003] The main purpose of the present invention is to provide an intermediate layer structure for solar cells and a preparation method and application thereof, so as to solve the problems of low coverage of self-assembled monomolecular hole transport layer materials on TCO and uneven distribution of self-assembled monomolecular hole transport layer materials in the prior art.

[0004] In order to achieve the above-mentioned object, the present invention provides an intermediate layer structure for a solar cell, comprising: a transparent conductive oxide layer, a self-assembled monomolecular hole transport layer, and a self-assembled monomolecular connecting layer for connecting the transparent conductive oxide layer and the self-assembled monomolecular hole transport layer;

[0005] The self-assembled monomolecular hole transport layer includes a self-assembled monomolecular layer material having phosphonic acid end groups;

[0006] The self-assembled monomolecular connecting layer includes at least one of a silane-based self-assembled monomolecular layer material and a carboxylic acid-based self-assembled monomolecular layer material, and the silane-based self-assembled monomolecular layer material and the carboxylic acid-based self-assembled monomolecular layer material have a thiol group.

[0007] Furthermore, the self-assembled monolayer material of the phosphonic acid end group is selected from at least one of 2PACz, MeO-2PACz, Me-2PACz, 4PACz, Me-4PACz, and MeO-4PACz.

[0008] Furthermore, the transparent conductive oxide layer includes at least one of ITO, FTO, IZO and AZO.

[0009] Preferably, the thickness of the transparent conductive oxide layer is 10 nm to 30 nm.

[0010] Preferably, the thickness of the self-assembled monomolecular connecting layer is 1 nm to 5 nm, and the thickness of the self-assembled monomolecular hole transport layer is 1 nm to 5 nm.

[0011] Furthermore, the silane self-assembled monolayer material is selected from at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and (mercaptomethyl)triethoxysilane.

[0012] Furthermore, the carboxylic acid self-assembled monolayer material is selected from at least one of 3-mercaptopropionic acid, thioglycolic acid, mercaptoformic acid, and mercaptosuccinic acid.

[0013] Preferably, the carboxylic acid self-assembled monolayer material is selected from at least one of 3-mercaptopropionic acid and thioglycolic acid.

[0014] According to another aspect of the present invention, there is provided a method for preparing the intermediate layer structure for a solar cell as described above, comprising the following steps:

[0015] Step S1, depositing a self-assembled monomolecular connecting layer material on the transparent conductive oxide layer by a coating method or a vacuum evaporation method to form a self-assembled monomolecular connecting layer;

[0016] Step S2, using a coating method or a vacuum evaporation method to deposit a self-assembled monolayer material with phosphonic acid end groups on the self-assembled monolayer connecting layer to obtain an intermediate layer structure for a solar cell.

[0017] Furthermore, in step S1, a coating liquid containing a self-assembled monomolecular connecting layer material is coated on the transparent conductive oxide layer by a coating method, and the self-assembled monomolecular connecting layer is obtained after removing the solvent.

[0018] Preferably, in the coating solution containing the self-assembled monomolecular connecting layer material, the solvent is selected from at least one of ethanol and isopropanol, and the concentration of the self-assembled monomolecular connecting layer material is 0.2 mg / L to 2 mg / L.

[0019] More preferably, in step S1, the solvent is removed by volatilization at room temperature.

[0020] Preferably, in step S2, a coating liquid of a self-assembled monolayer material containing phosphonic acid end groups is coated on the self-assembled monolayer connecting layer by a coating method, and an intermediate layer structure for a solar cell is obtained by annealing.

[0021] More preferably, in the coating solution of the self-assembled monolayer material containing phosphonic acid end groups, the solvent is selected from at least one of ethanol and isopropanol, and the concentration of the self-assembled monolayer material containing phosphonic acid end groups is 0.2 mg / L to 2 mg / L.

[0022] More preferably, in the annealing treatment, the annealing temperature is 80° C. to 120° C., and the annealing time is 5 min to 30 min.

[0023] Preferably, the conductive oxide layer is prepared by PVD or ALD.

[0024] Preferably, step S1 further comprises plasma treating the conductive oxide layer.

[0025] According to another aspect of the present invention, there is provided an application of the above intermediate layer structure for solar cells, which is used for the preparation of single-junction perovskite solar cells, perovskite tandem solar cells or perovskite crystalline silicon tandem solar cells.

[0026] According to another aspect of the present invention, a perovskite crystalline silicon tandem solar cell is provided, which comprises a crystalline silicon cell stacked in sequence, an intermediate layer structure for a solar cell as described above, a perovskite absorption layer, a passivation layer, an electron transport layer, a transparent electrode layer, a metal electrode layer and an anti-reflection layer, wherein a transparent conductive oxide layer, a self-assembled monomolecular connection layer and a self-assembled monomolecular hole transport layer are stacked in sequence on the crystalline silicon cell.

[0027] Furthermore, the passivation layer includes at least one of MgF2, LiF, NaF, PDI, PI, PDAI, PEAI, and AlOx.

[0028] Furthermore, the electron transport layer comprises C 60 , PCBM, ZnO, SnO2, and PC71BM.

[0029] Furthermore, the transparent electrode layer includes at least one of ITO, FTO, IZO, AZO, IWO, IZrO, and ATO.

[0030] Furthermore, the metal electrode layer includes at least one of Ag, Cu, Au, and Al.

[0031] Furthermore, the anti-reflection layer includes at least one of MgF2, LiF, PDMS, NaF, SiO2, and SiN.

[0032] By applying the technical solution of the present invention, an intermediate layer structure for a solar cell is provided, in which a layer of a self-assembled monomolecular material having a thiol group is inserted between a traditional self-assembled monomolecular hole transport layer and TCO, and the thiol group interacts with the phosphonic acid group in the self-assembled monomolecular hole transport layer material to enhance the anchoring and uniformity of the self-assembled monomolecular hole transport layer material on the TCO, thereby improving the coverage and uniformity of the self-assembled monomolecular hole transport layer material on the TCO, and thus improving the efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 A schematic diagram of a perovskite crystalline silicon tandem solar cell according to an embodiment of the present invention is shown.

[0035] The above drawings include the following reference numerals:

[0036] 1. Crystalline silicon cell; 2. Transparent conductive oxide layer; 3. Self-assembled monomolecular connection layer; 4. Self-assembled monomolecular hole transport layer; 5. Perovskite absorption layer; 6. Passivation layer; 7. Electron transport layer; 8. Buffer layer; 9. Transparent electrode layer; 10. Metal electrode layer; 11. Anti-reflection layer. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] As described in the background art, the prior art has the problems of low coverage of the self-assembled monomolecular hole transport layer material on the TCO and uneven distribution of the self-assembled monomolecular hole transport layer material. In order to solve the above problems and to achieve the above objectives, according to one aspect of the present invention, Figure 1 As shown, an intermediate layer structure for a solar cell is provided, comprising: a transparent conductive oxide layer 2, a self-assembled monomolecular hole transport layer 4, and a self-assembled monomolecular connecting layer 3 for connecting the transparent conductive oxide layer 2 and the self-assembled monomolecular hole transport layer 4; the self-assembled monomolecular hole transport layer 4 comprises a self-assembled monomolecular layer material with a phosphonic acid end group; the self-assembled monomolecular connecting layer 3 comprises at least one of a silane self-assembled monomolecular layer material and a carboxylic acid self-assembled monomolecular layer material, and the silane self-assembled monomolecular layer material and the carboxylic acid self-assembled monomolecular layer material have a thiol group.

[0039] In order to obtain better battery performance, the present invention provides an intermediate layer structure for solar cells, by inserting a layer of self-assembled monolayer material having a thiol group between a traditional self-assembled monomolecular hole transport layer 4 (SAM-HTL) and a transparent conductive oxide layer 2 (TCO), and by interacting between the thiol group and the phosphonic acid group in the SAM-HTL, the anchoring and uniformity of the SAM-HTL on the TCO are enhanced, and the coverage and uniformity of the self-assembled monomolecular hole transport layer material on the TCO are improved, thereby improving the efficiency of the solar cell.

[0040] In some embodiments, the self-assembled monolayer material of the phosphonic acid end group is selected from at least one of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphonic acid (Me-2PACz), [4-(9H-carbazole-9-yl)butyl]phosphonic acid (4PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz). Types, including but not limited to the above materials, other carbazole phosphate type hole transport materials that can provide phosphonic acid end groups are also suitable for the present invention. In the prior art, the self-assembled monolayer material of the phosphonic acid end group extracts holes by forming a self-assembled monolayer on TCO, and a layer of self-assembled monolayer material with a thiol group is inserted between the self-assembled monolayer material of the phosphonic acid end group and TCO. The anchoring ability and uniformity of the self-assembled monolayer material of the phosphonic acid end group on TCO are enhanced through the interaction between the phosphonic acid group and the thiol group, and the sensitivity of the self-assembled monolayer hole transport layer 4 material to the roughness of the TCO substrate is reduced, thereby improving the coverage and uniformity of the self-assembled monolayer hole transport layer 4 material on TCO.

[0041] In some embodiments, the transparent conductive oxide layer 2 includes at least one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO); preferably, the thickness of the transparent conductive oxide layer 2 is 10nm to 30nm; preferably, the thickness of the self-assembled monomolecular connecting layer 3 is 1nm to 5nm, and the thickness of the self-assembled monomolecular hole transport layer 4 is 1nm to 5nm, so that the self-assembled monomolecular hole transport layer material can effectively cover the TCO and obtain a higher charge mobility.

[0042] In some embodiments, the silane-based self-assembled monolayer material is selected from at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and (mercaptomethyl)triethoxysilane.

[0043] In some embodiments, the carboxylic acid self-assembled monolayer material is selected from at least one of 3-mercaptopropionic acid, thioglycolic acid, mercaptoformic acid, and mercaptosuccinic acid; preferably, the carboxylic acid self-assembled monolayer material is selected from at least one of 3-mercaptopropionic acid and thioglycolic acid, so as to obtain a higher coverage of the self-assembled monolayer material of the phosphonic acid end group and a higher charge mobility, thereby improving the battery efficiency.

[0044] According to another aspect of the present invention, a method for preparing the above intermediate layer structure for solar cells is provided, comprising the following steps: step S1, using a coating method or a vacuum evaporation method to deposit a self-assembled monomolecular connection layer material on a transparent conductive oxide layer to form a self-assembled monomolecular connection layer, so that the subsequent self-assembled monomolecular material of the phosphonic acid end group can be evenly covered; step S3, using a coating method or a vacuum evaporation method to deposit a self-assembled monomolecular layer material of the phosphonic acid end group on the self-assembled monomolecular connection layer to obtain an intermediate layer structure for solar cells. The method is used for the intermediate layer structure of solar cells, and the process is simple and the cost is low.

[0045] In some embodiments, in step S1, a coating liquid containing a self-assembled monomolecular connection layer material is coated on the transparent conductive oxide layer by a coating method, and a self-assembled monomolecular connection layer is obtained after removing the solvent; preferably, in the coating liquid containing the self-assembled monomolecular connection layer material, the solvent is selected from at least one of ethanol and isopropanol, and the concentration of the self-assembled monomolecular connection layer material is 0.2-2 mg / L, so as to form a uniformly distributed self-assembled monomolecular connection layer; more preferably, in step S1, the solvent is removed by volatilization at room temperature, and the self-assembled monomolecular connection layer can be prepared at room temperature; preferably, in step S2, a coating liquid containing a self-assembled monomolecular connection layer material containing a phosphonic acid end group is coated on the self-assembled monomolecular connection layer by a coating method, and an intermediate layer structure for a solar cell is obtained after annealing; preferably, in the coating liquid containing the self-assembled monomolecular connection layer material containing a phosphonic acid end group, the solvent is selected from ethyl acetate, ... At least one of alcohol and isopropanol, the concentration of the self-assembled monolayer material of the phosphonic acid end group is 0.2mg / L~2mg / L; more preferably, in the annealing treatment, the annealing temperature is 80℃~120℃, and the annealing time is 5min~30min to form a dense self-assembled monolayer hole transport layer; preferably, in step S1 and step S2, the coating method is selected from a slit coating method and a spin coating method respectively and independently; preferably, the conductive oxide layer is prepared by PVD or ALD, and the transparent conductive oxide layer is prepared by PVD technology or ALD technology, and the formed film is uniform and flat with high production efficiency; preferably, step S1 also includes plasma treatment of the conductive oxide layer to increase the wettability of the self-assembled monolayer connecting layer material and better spread the self-assembled monolayer connecting layer material, thereby improving the coverage and uniformity of the self-assembled monolayer material of the phosphonic acid end group.

[0046] According to another aspect of the present invention, an application of the above intermediate layer structure for solar cells is provided, which is used for the preparation of single-junction perovskite solar cells, perovskite tandem solar cells or perovskite crystalline silicon tandem solar cells. The self-assembled monomolecular connection layer 3 is inserted between the transparent conductive oxide and the self-assembled monomolecular hole transport layer 4, which can improve the coverage and uniformity of the self-assembled monomolecular hole transport layer 4 material on the TCO, thereby improving the hole transport efficiency of the self-assembled monomolecular hole transport layer 4, and can improve the cell efficiency of the single-junction perovskite solar cell, perovskite tandem solar cell or perovskite crystalline silicon tandem solar cell having the intermediate layer structure.

[0047] According to another aspect of the present invention, Figure 1 As shown, a perovskite crystalline silicon tandem solar cell is provided, the perovskite crystalline silicon tandem solar cell comprises a crystalline silicon cell 1 stacked in sequence, an intermediate layer structure for solar cells as described above, a perovskite absorption layer 5, a passivation layer 6, an electron transport layer 7, a transparent electrode layer 9, a metal electrode layer 10 and an anti-reflection layer 11, and a transparent conductive oxide layer 2, a self-assembled monomolecular connection layer 3 and a self-assembled monomolecular hole transport layer 4 are stacked in sequence on the crystalline silicon cell 1. The intermediate layer structure can realize efficient charge transfer between the crystalline silicon sub-cell and the perovskite sub-cell, and improve the photovoltaic efficiency of the tandem cell; the perovskite / TOPCon tandem cell and the perovskite / silicon-based heterojunction tandem cell in the perovskite / crystalline silicon tandem cell are both considered to be the most promising solar cell tandem cells. In a preferred embodiment, the crystalline silicon cell 1 is a TOPCon cell or a silicon-based heterojunction cell.

[0048] In some embodiments, the passivation layer 6 includes magnesium fluoride (MgF2), lithium fluoride (LiF), sodium fluoride (NaF), piperazine diiodide (PDI), piperazine iodide (PI), propylene diamine hydroiodide (PDAI), phenethylammonium iodide (PEAI), aluminum oxide (AlO x ) at least one of; preferably the thickness of the passivation layer 6 is 0.5nm ~ 2nm.

[0049] In some embodiments, the electron transport layer 7 includes C 60 , PCBM, ZnO, SnO2, PC71BM; preferably, the thickness of the electron transport layer 7 is 1nm to 20nm.

[0050] In some embodiments, a buffer layer 8 is disposed between the electron transport layer 7 and the transparent electrode layer 9, and the buffer layer 8 includes at least one of SnO2, BCP, ZnO, AZO, MoO3, and Y2O3; preferably, the thickness of the buffer layer 8 is 50 nm to 100 nm.

[0051] In some embodiments, the transparent electrode layer 9 includes at least one of ITO, FTO, IZO, AZO, IWO, IZrO, and ATO; preferably, the thickness of the transparent electrode layer 9 is 50 nm to 100 nm.

[0052] In some embodiments, the metal electrode layer 10 includes at least one of Ag, Cu, Au, and Al; preferably, the thickness of the metal electrode layer 10 is 300 nm to 500 nm.

[0053] In some embodiments, the anti-reflection layer 11 includes magnesium fluoride (MgF2), lithium fluoride (LiF), polydimethylsiloxane (PDMS), sodium fluoride (NaF), silicon oxide (SiO2), silicon nitride (SiN x ) at least one; preferably, the thickness of the anti-reflection layer 11 is 100nm to 150nm.

[0054] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0055] Example 1

[0056] A perovskite crystalline silicon stacked solar cell comprises a crystalline silicon heterojunction bottom cell, a first indium tin oxide layer, a 3-mercaptopropyltrimethoxysilane self-assembled monolayer, a 2PACz self-assembled monolayer, a perovskite absorption layer, a first MgF2 layer, a PCBM layer, a BCP layer, a second indium tin oxide layer, an Ag electrode layer and a second MgF2 layer which are stacked in sequence from bottom to top; wherein the thickness of the first indium tin oxide layer is 20 nm, the thickness of the 3-mercaptopropyltrimethoxysilane self-assembled monolayer is 2 nm, the thickness of the 2PACz self-assembled monolayer is 2 nm, the thickness of the perovskite absorption layer is 1 μm, the thickness of the first MgF2 layer is 1 nm, the thickness of the PCBM layer is 10 nm, the thickness of the BCP layer is 80 nm, the thickness of the second indium tin oxide layer is 80 nm, the thickness of the Ag electrode layer is 400 nm, and the thickness of the second MgF2 layer is 120 nm;

[0057] Specifically, the preparation steps of the perovskite crystalline silicon tandem solar cell are as follows:

[0058] Step 1: Prepare a first indium tin oxide layer on a crystalline silicon heterojunction bottom cell using PVD technology;

[0059] Step 2: The first indium tin oxide layer is treated with plasma gas for 15 minutes, and then a coating liquid containing 3-mercaptopropyltrimethoxysilane is coated on the first indium tin oxide layer by a slit coating method, and the solvent is evaporated at room temperature to obtain a 3-mercaptopropyltrimethoxysilane self-assembled monolayer; wherein the solvent in the coating liquid is ethanol, and the concentration of 3-mercaptopropyltrimethoxysilane in the coating liquid is 1 mg / L;

[0060] Step 3: coating the coating liquid containing 2PACz onto the 3-mercaptopropyltrimethoxysilane self-assembled monolayer by a slit coating method, and annealing at 100° C. for 10 min to obtain a 2PACz self-assembled monolayer; wherein the solvent in the coating liquid is ethanol, and the concentration of 2PACz in the coating liquid is 1 mg / L;

[0061] Step 4: The perovskite precursor solution is coated onto the 2PACz self-assembled monolayer by slit coating, which is then placed in a vacuum pump for 30 seconds and then annealed at 120°C for 10 minutes to obtain the perovskite absorption layer Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.75 Br 0.25 )3;

[0062] Step 5, using evaporation technology to sequentially prepare a first MgF2 layer, a PCBM layer, and a BCP layer on the perovskite layer;

[0063] Step 6, preparing a second indium tin oxide layer on the BCP layer using PVD technology;

[0064] Step seven, using evaporation technology to sequentially prepare an Ag electrode layer and a second MgF2 layer on the second indium tin oxide layer.

[0065] Example 2

[0066] A perovskite crystalline silicon stacked solar cell, the structure of which is different from that of Example 1 only in that the first indium tin oxide layer is replaced by an FTO layer, the 3-mercaptopropyltrimethoxysilane self-assembled monolayer is replaced by a 3-mercaptopropionic acid self-assembled monolayer, the 2PACz self-assembled monolayer is replaced by a MeO-2PACz self-assembled monolayer, the FTO layer has a thickness of 30 nm, the 3-mercaptopropionic acid self-assembled monolayer has a thickness of 5 nm, and the MeO-2PACz self-assembled monolayer has a thickness of 5 nm.

[0067] The preparation steps thereof are different from those of Example 1 only in that the MeO-2PACz self-assembled monolayer and the 3-mercaptopropionic acid self-assembled monolayer are prepared by vacuum evaporation method, respectively.

[0068] Example 3

[0069] A perovskite crystalline silicon stacked solar cell, the structure of which is different from that of Example 1 only in that the first indium tin oxide layer is replaced by an IZO layer, the 3-mercaptopropyltrimethoxysilane self-assembled monolayer is replaced by a 3-mercaptopropionic acid self-assembled monolayer, the 2PACz self-assembled monolayer is replaced by a Me-4PACz self-assembled monolayer, the thickness of the IZO layer is 10 nm, the thickness of the 3-mercaptopropionic acid self-assembled monolayer is 2 nm, and the thickness of the Me-4PACz self-assembled monolayer is 2 nm.

[0070] The preparation steps thereof are different from those of Example 1 only in that the Me-4PACz self-assembled monolayer and the 3-mercaptopropionic acid self-assembled monolayer are prepared by spin coating, respectively.

[0071] Example 4

[0072] The only difference between it and Example 1 is that the material of the self-assembled monomolecular connecting layer is 3-mercaptopropionic acid.

[0073] Example 5

[0074] The only difference between the embodiment 1 and the embodiment 1 is that the material of the self-assembled monomolecular connecting layer is thioglycolic acid.

[0075] Example 6

[0076] The only difference between it and Example 1 is that the material of the self-assembled monomolecular connecting layer is 3-mercaptopropyltriethoxysilane.

[0077] Example 7

[0078] The only difference between the embodiment 1 and the embodiment 1 is that the material of the self-assembled monomolecular connecting layer is 3-mercaptopropylmethyldimethoxysilane.

[0079] Example 8

[0080] The only difference between it and Example 1 is that the material of the self-assembled monomolecular connecting layer is (mercaptomethyl)triethoxysilane.

[0081] Example 9

[0082] The only difference between it and Example 1 is that the material of the self-assembled monomolecular connecting layer is mercaptoformic acid.

[0083] Example 10

[0084] The only difference between the embodiment 1 and the embodiment 1 is that the material of the self-assembled monomolecular connecting layer is mercaptosuccinic acid.

[0085] Comparative Example 1

[0086] The only difference between the embodiment 1 and the embodiment 1 is that the embodiment 1 does not have a 3-mercaptopropyltrimethoxysilane self-assembled monolayer.

[0087] Specifically, the perovskite crystalline silicon stacked solar cell includes a crystalline silicon heterojunction bottom cell, a first indium tin oxide layer, a 2PACz self-assembled monolayer, a perovskite absorption layer, a first MgF2 layer, a PCBM layer, a BCP layer, a second indium tin oxide layer, an Ag electrode layer and a second MgF2 layer stacked in sequence from bottom to top; wherein the thickness of the first indium tin oxide layer is 20nm, the thickness of the PACz self-assembled monolayer is 2nm, the thickness of the perovskite absorption layer is 1μm, the thickness of the first MgF2 layer is 1nm, the thickness of the PCBM layer is 10nm, the thickness of the BCP layer is 80nm, the thickness of the second indium tin oxide layer is 80nm, the thickness of the Ag electrode layer is 400nm, and the thickness of the second MgF2 layer is 120nm;

[0088] Specifically, the preparation steps of the perovskite crystalline silicon tandem solar cell are as follows:

[0089] Step 1: Prepare a first indium tin oxide layer on a crystalline silicon heterojunction bottom cell using PVD technology;

[0090] Step 2: The first indium tin oxide layer is coated with a coating solution containing 2PACz by a slit coating method using plasma gas for 15 minutes, and the solvent is evaporated at room temperature at 100° C. for 10 minutes to obtain a 2PACz self-assembled monolayer; wherein the solvent in the coating solution is ethanol, and the concentration of 2PACz in the coating solution is 1 mg / L;

[0091] Step 3: The perovskite precursor solution is coated onto the 2PACz self-assembled monolayer by slit coating, which is then placed in a vacuum pump for 30 seconds and then annealed at 120°C for 10 minutes to obtain the perovskite absorption layer Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.75 Br 0.25 )3;

[0092] Step 4, using evaporation technology to sequentially prepare a first MgF2 layer, a PCBM layer, and a BCP layer on the perovskite layer;

[0093] Step 5, preparing a second indium tin oxide layer on the BCP layer using PVD technology;

[0094] Step six, using evaporation technology to sequentially prepare an Ag electrode layer and a second MgF2 layer on the second indium tin oxide layer.

[0095] Comparative Example 2

[0096] The only difference between the embodiment 1 and the embodiment 1 is that the embodiment 1 does not have a 3-mercaptopropyltrimethoxysilane self-assembled monolayer and uses 3-mercaptopropyltrimethoxysilane and 2PACz as hole transport layer materials.

[0097] Specifically, the perovskite crystalline silicon stacked solar cell includes a crystalline silicon heterojunction bottom cell, a first indium tin oxide layer, a hole transport layer, a perovskite absorption layer, a first MgF2 layer, a PCBM layer, a BCP layer, a second indium tin oxide layer, an Ag electrode layer and a second MgF2 layer stacked in sequence from bottom to top; wherein the thickness of the first indium tin oxide layer is 20nm, the thickness of the hole transport layer is 4nm, the thickness of the perovskite absorption layer is 1μm, the thickness of the first MgF2 layer is 1nm, the thickness of the PCBM layer is 10nm, the thickness of the BCP layer is 80nm, the thickness of the second indium tin oxide layer is 80nm, the thickness of the Ag electrode layer is 400nm, and the thickness of the second MgF2 layer is 120nm; the hole transport layer is composed of 3-mercaptopropyltrimethoxysilane and 2PACz.

[0098] Specifically, the preparation steps of the perovskite crystalline silicon tandem solar cell are as follows:

[0099] Step 1: Prepare a first indium tin oxide layer on a crystalline silicon heterojunction bottom cell using PVD technology;

[0100] Step 2: The first indium tin oxide layer is treated with plasma gas for 15 minutes, and then a coating solution containing 3-mercaptopropyltrimethoxysilane and 2PACz is coated on the first indium tin oxide layer by a slit coating method, and annealed at 100° C. for 10 minutes to obtain a hole transport layer; wherein the solvent in the coating solution is ethanol, the concentration of 3-mercaptopropyltrimethoxysilane in the coating solution is 1 mg / L, and the concentration of 2PACz is 1 mg / L;

[0101] Step 3: The perovskite precursor solution is coated onto the 2PACz self-assembled monolayer by slit coating, which is then placed in a vacuum pump for 30 seconds and then annealed at 120°C for 10 minutes to obtain the perovskite absorption layer Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.75 Br 0.25 )3;

[0102] Step 4, using evaporation technology to sequentially prepare a first MgF2 layer, a PCBM layer, and a BCP layer on the perovskite layer;

[0103] Step 5, preparing a second indium tin oxide layer on the BCP layer using PVD technology;

[0104] Step six, using evaporation technology to sequentially prepare an Ag electrode layer and a second MgF2 layer on the second indium tin oxide layer.

[0105] Comparative Example 3

[0106] The only difference between the embodiment 1 and the embodiment 1 is that the 3-mercaptopropyltrimethoxysilane self-assembled monolayer is replaced by an octadecanoic acid self-assembled monolayer.

[0107] Comparative Example 4

[0108] The only difference between the embodiment 1 and the embodiment 1 is that the 3-mercaptopropyltrimethoxysilane self-assembled monolayer is replaced by a p-aminobenzenethiol self-assembled monolayer.

[0109] The performance of the perovskite crystalline silicon tandem solar cells prepared in the embodiments and comparative examples was tested. The photoelectric conversion efficiency (PCE), fill factor (FF), open circuit voltage (Voc) and short circuit current (Jsc) of the perovskite crystalline silicon tandem solar cells prepared in the above embodiments and comparative examples are shown in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] Note: “-” indicates that the corresponding layer structure does not exist in the battery.

[0114] As can be seen from Table 1, compared with Comparative Examples 1-4, Examples 1-10 insert a layer of silane self-assembled monolayer material or carboxylic acid self-assembled monolayer material between the traditional self-assembled monolayer hole transport layer and the transparent conductive oxide layer, and the resulting stacked solar cell has a higher open circuit voltage, short circuit current density and fill factor, and the cell efficiency is significantly improved.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An intermediate layer structure for a solar cell, characterized in that: include: A transparent conductive oxide layer, a self-assembled monomolecular hole transport layer, and a self-assembled monomolecular connecting layer for connecting the transparent conductive oxide layer and the self-assembled monomolecular hole transport layer; The self-assembled monomolecular hole transport layer includes a self-assembled monomolecular layer material with phosphonic acid end groups; The self-assembled monomolecular connecting layer includes at least one of a silane-based self-assembled monomolecular layer material and a carboxylic acid-based self-assembled monomolecular layer material, and the silane-based self-assembled monomolecular layer material and the carboxylic acid-based self-assembled monomolecular layer material have a thiol group.

2. The intermediate layer structure for solar cells according to claim 1, characterized in that: The self-assembled monolayer material of the phosphonic acid end group is selected from at least one of 2PACz, MeO-2PACz, Me-2PACz, 4PACz, Me-4PACz, and MeO-4PACz.

3. The intermediate layer structure for solar cells according to claim 1, characterized in that: The transparent conductive oxide layer includes at least one of ITO, FTO, IZO, and AZO; Preferably, the thickness of the transparent conductive oxide layer is 10 nm to 30 nm; Preferably, the thickness of the self-assembled monomolecular connecting layer is 1 nm to 5 nm, and the thickness of the self-assembled monomolecular hole transport layer is 1 nm to 5 nm.

4. The intermediate layer structure for a solar cell according to any one of claims 1 to 3, characterized in that: The silane self-assembled monolayer material is selected from at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and (mercaptomethyl)triethoxysilane.

5. The intermediate layer structure for a solar cell according to any one of claims 1 to 3, characterized in that: The carboxylic acid self-assembled monolayer material is selected from at least one of 3-mercaptopropionic acid, thioglycolic acid, mercaptoformic acid, and mercaptosuccinic acid; Preferably, the carboxylic acid self-assembled monolayer material is selected from at least one of 3-mercaptopropionic acid and thioglycolic acid.

6. The method for preparing an intermediate layer structure for a solar cell according to any one of claims 1 to 5, characterized in that: The steps include: Step S1, depositing a self-assembled monomolecular connecting layer material on the transparent conductive oxide layer by a coating method or a vacuum evaporation method to form a self-assembled monomolecular connecting layer; Step S2, using a coating method or a vacuum evaporation method to deposit a self-assembled monolayer material with phosphonic acid end groups on the self-assembled monolayer connecting layer to obtain the intermediate layer structure for the solar cell.

7. The method for preparing an intermediate layer structure for a solar cell according to claim 6, characterized in that: In the step S1, a coating liquid containing a self-assembled monomolecular connection layer material is coated on the transparent conductive oxide layer by a coating method, and the self-assembled monomolecular connection layer is obtained after removing the solvent; Preferably, in the coating solution containing the self-assembled monomolecular connecting layer material, the solvent is selected from at least one of ethanol and isopropanol, and the concentration of the self-assembled monomolecular connecting layer material is 0.2 mg / L to 2 mg / L; More preferably, in the step S1, the solvent is removed by volatilization at room temperature; Preferably, in the step S2, a coating liquid of a self-assembled monolayer material containing phosphonic acid end groups is coated on the self-assembled monolayer connecting layer by a coating method, and the intermediate layer structure for a solar cell is obtained by annealing; More preferably, in the coating solution of the self-assembled monolayer material containing phosphonic acid end groups, the solvent is selected from at least one of ethanol and isopropanol, and the concentration of the self-assembled monolayer material containing phosphonic acid end groups is 0.2 mg / L to 2 mg / L; More preferably, in the annealing treatment, the annealing temperature is 80°C to 120°C, and the annealing time is 5min to 30min; Preferably, the conductive oxide layer is prepared by PVD or ALD; Preferably, step S1 further comprises plasma treating the conductive oxide layer.

8. Use of the intermediate layer structure for solar cells according to any one of claims 1 to 5, characterized in that: Used for the preparation of single-junction perovskite solar cells, perovskite tandem solar cells or perovskite crystalline silicon tandem solar cells.

9. A perovskite crystalline silicon tandem solar cell, characterized in that: The perovskite crystalline silicon tandem solar cell comprises a crystalline silicon cell stacked in sequence, an intermediate layer structure for a solar cell according to any one of claims 1 to 5, a perovskite absorption layer, a passivation layer, an electron transport layer, a transparent electrode layer, a metal electrode layer and an anti-reflection layer, wherein a transparent conductive oxide layer, a self-assembled monomolecular connection layer and a self-assembled monomolecular hole transport layer are stacked in sequence on the crystalline silicon cell.

10. The perovskite crystalline silicon tandem solar cell according to claim 9, characterized in that: The passivation layer includes at least one of MgF2, LiF, NaF, PDI, PI, PDAI, PEAI, and AlOx; and / or, The electron transport layer comprises C 60 , PCBM, ZnO, SnO2, PC71BM; and / or, The transparent electrode layer includes at least one of ITO, FTO, IZO, AZO, IWO, IZrO, and ATO; and / or, The metal electrode layer includes at least one of Ag, Cu, Au, and Al; and / or, The anti-reflection layer includes at least one of MgF2, LiF, PDMS, NaF, SiO2, and SiN.

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