Perovskite / crystalline silicon laminated solar cell and preparation method thereof

Abstract

The invention provides a perovskite / crystalline silicon laminated solar cell and a preparation method thereof. The perovskite / crystalline silicon laminated solar cell comprises a crystalline silicon bottom cell, a first transparent oxide conductive layer, a first carrier transport layer, a perovskite active layer, a second carrier transport layer, a buffer layer, a second transparent oxide conductive layer and a metal electrode layer which are sequentially laminated, and further comprises an interface modification layer, the interface modification layer is arranged between the first carrier transport layer and the perovskite active layer, and the material of the interface modification layer comprises a benzodithiophene compound shown in a formula (I). The liquid crystal micromolecule shown in the formula (I) has long-range ordered arrangement and good crystallinity, can play a role of a nucleating agent in the nucleation process of a perovskite active material, and can effectively improve the crystallization quality of a perovskite active layer. The arrangement of the interface modification layer can improve the photovoltaic performance and stability of the perovskite / crystalline silicon laminated solar cell. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and in particular, to a perovskite / crystalline silicon tandem solar cell and a preparation method thereof. Background Art

[0002] Organic-inorganic hybrid perovskite solar cells are considered ideal candidates for future photovoltaic applications due to their excellent photovoltaic performance. The perovskite / crystalline silicon tandem solar cell prepared by stacking with a crystalline silicon bottom cell is regarded as an effective means to break through the theoretical limit. In the tandem cell, the recombination loss at the interface is the main cause of the voltage loss of the perovskite top cell and the tandem cell. The interface recombination between the hole transport layer and the perovskite layer is even more dominant, severely restricting the improvement of device performance. This is mainly because the hole transport layer suitable for the textured crystalline silicon bottom cell is usually NiOx prepared by magnetron sputtering, which has poor permeability and a high surface defect state density, and is very easy to become a recombination center.

[0003] Although the surface defects of NiOx can be improved by spin-coating a small molecule self-assembled layer, such as 2PACz or 4PACz, on the surface of NiOx, the wettability of 2PACz and 4PACz is poor, which is extremely likely to cause the surface of the subsequently prepared perovskite film to be uneven, or even unable to be spin-coated. In addition, the solvent of the small molecule self-assembled layer usually uses an alcohol solution, and the evaporation rate is relatively fast, making it difficult to control the crystallization rate of the film.

[0004] On this basis, researching and developing an interface modification layer that can reduce the interface recombination loss between the hole transport layer and the perovskite active layer, improve the surface defects of the hole transport layer, and is easy to be prepared by spin-coating method is of great significance for improving the photovoltaic performance and stability of the perovskite / crystalline silicon tandem solar cell. Summary of the Invention

[0005] The main object of the present invention is to provide a perovskite / crystalline silicon tandem solar cell and a preparation method thereof, so as to solve the problems in the prior art that the interface recombination loss between the hole transport layer and the perovskite active layer in the perovskite / crystalline silicon tandem solar cell is serious, there are many surface defects in the hole transport layer, and the preparation of the traditional interface modification layer is difficult and affects the preparation of the subsequent perovskite active layer, resulting in poor photovoltaic performance and stability of the perovskite / crystalline silicon tandem solar cell.

[0006] To achieve the above object, on the one hand, the present invention provides a perovskite / silicon heterojunction solar cell, comprising a silicon bottom cell, a first transparent oxide conductive layer, a first carrier transport layer, a perovskite active layer, a second carrier transport layer, a buffer layer, a second transparent oxide conductive layer and a metal electrode layer which are sequentially stacked. The perovskite / silicon heterojunction solar cell further comprises an interface modification layer, which is disposed between the first carrier transport layer and the perovskite active layer, and the material of the interface modification layer comprises a benzodithiophene compound represented by formula (I).

[0007]

[0008] Wherein, R1 is selected from C1-C 16 alkyl, R2 is selected from a halogen atom or C1-C 10 alkyl, R3 and R4 are each independently selected from C1-C8 alkyl, and R5 is selected from C1-C8 alkyl.

[0009] Further, R1 is selected from C1-C 16 linear or branched alkyl, preferably C8-C 16 branched alkyl, more preferably 2-ethyl-hexyl, 4-butyl-octyl or 6-hexyl-decyl; R2 is selected from a halogen atom or C1-C 10 linear or branched alkyl, preferably Cl or n-hexyl, more preferably Cl; R3 and R4 are each independently selected from C1-C8 linear or branched alkyl, preferably n-hexyl, n-octyl, n-decyl or ethylhexyl; R5 is selected from C1-C8 linear or branched alkyl, preferably n-hexyl, n-octyl or ethylhexyl.

[0010] Further, the benzodithiophene compound represented by formula (I) is selected from any one of the following compounds:

[0011]

[0012]

[0013] Further, the thickness of the interface modification layer is 5-15 nm.

[0014] Further, the first carrier transport layer is a hole transport layer, and the second carrier transport layer is an electron transport layer.

[0015] Further, the thickness of the first carrier transport layer is 1-5 nm.

[0016] Further, the thickness of the perovskite active layer is 500-1000 nm.

[0017] Further, the thickness of the second carrier transport layer is 10-30 nm.

[0018] Further, the thickness of the first transparent oxide conductive layer is 5 - 35 nm.

[0019] Further, the thickness of the buffer layer is 10 - 30 nm.

[0020] Further, the thickness of the second transparent oxide conductive layer is 70 - 110 nm.

[0021] Further, the thickness of the metal electrode layer is 100 - 150 nm or 10 - 15 μm.

[0022] Further, the crystalline silicon bottom cell is selected from HJT cells, TOPCon cells or IBC cells.

[0023] Further, the materials of the first transparent oxide conductive layer and the second transparent oxide conductive layer are each independently selected from one or more of the group consisting of indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, and indium zirconium oxide.

[0024] Further, the material of the first carrier transport layer is selected from one or more of the group consisting of NiO x , MoO3, V2O5, and CuSCN.

[0025] Further, the band gap of the perovskite active layer is 1.60 - 1.70 eV, and preferably the material of the perovskite active layer is selected from ABX3, where A is CH3NH3 + , NH = CHNH3 + or Cs + , B is Pb 2+ or Sn 2+ , X is I - , Cl - or Br - .

[0026] Further, the material of the second carrier transport layer is selected from PCBM and / or C 60 .

[0027] Further, the material of the buffer layer is selected from tin dioxide and / or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

[0028] Further, the material of the metal electrode layer is selected from one or more of the group consisting of gold, silver, and copper.

[0029] To achieve the above object, another aspect of the present invention further provides a method for preparing the above-mentioned perovskite / silicon heterojunction solar cell provided by the present application, which includes sequentially preparing a first transparent oxide conductive layer, a first carrier transport layer, a perovskite active layer, a second carrier transport layer, a buffer layer, a second transparent oxide conductive layer and a metal electrode layer on the surface of the silicon bottom cell. The method for preparing the perovskite / silicon heterojunction solar cell further includes: preparing an interface modification layer on the surface of the first carrier transport layer away from the first transparent oxide conductive layer. The method for preparing the interface modification layer includes: coating a mixed solution containing the benzodithiophene compound shown in formula (I) on the surface of the first carrier transport layer away from the first transparent oxide conductive layer, and obtaining the interface modification layer after annealing treatment; or, depositing the benzodithiophene compound shown in formula (I) on the surface of the first carrier transport layer away from the first transparent oxide conductive layer by evaporation to obtain the interface modification layer.

[0030] Further, spin coating, slot die coating or blade coating is used for coating; preferably, in the mixed solution, the mass concentration of the benzodithiophene compound shown in formula (I) is 5-10 mg / mL, and the preferred spin coating speed is 3000-5000 rpm; preferably, the solvent in the mixed solution is selected from chlorobenzene.

[0031] Further, the temperature of the annealing treatment is 100-150 °C, and the time is 5-15 min.

[0032] Further, using the benzodithiophene compound shown in formula (I) as an evaporation source, the interface modification layer is prepared by vacuum evaporation. During the evaporation process, the heating temperature of the evaporation source is 300-600 °C, the vacuum degree is 2×10 -3 ~6×10 -4 Pa, and the evaporation rate is

[0033] Further, the buffer layer is prepared by atomic layer deposition.

[0034] Further, the second transparent oxide conductive layer is prepared by magnetron sputtering.

[0035] Applying the technical solution of the present invention, the liquid crystal small molecules of the benzodithiophene compound shown in formula (I) of the present application have a long-range ordered arrangement and good crystallinity, and can play the role of a nucleating agent during the nucleation process of the perovskite active material, and can effectively improve the crystallization quality of the perovskite active layer. By providing an interface modification layer containing the benzodithiophene compound shown in formula (I) between the first carrier transport layer and the perovskite active layer, the carrier lifetime can be effectively extended, the photocurrent decay time can be shortened, exciton dissociation can be promoted, facilitating the transport and collection of charges, and at the same time, the defects on the surface of the first carrier transport layer can be passivated, thereby improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic 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:

[0037] Figure 1 The stacked structure diagram of the perovskite / silicon heterojunction solar cell of the present invention is shown.

[0038] Among them, the above-mentioned drawings include the following reference numerals:

[0039] 10. Silicon bottom cell; 20. First transparent oxide conductive layer; 30. First carrier transport layer; 40. Perovskite active layer; 50. Second carrier transport layer; 60. Buffer layer; 70. Second transparent oxide conductive layer; 80. Metal electrode layer; 90. Interface modification layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0041] As described in the background art, there are serious problems in the existing perovskite / silicon heterojunction solar cell, such as severe interfacial recombination loss between the hole transport layer and the perovskite active layer, many defects on the surface of the hole transport layer, and difficulties in preparing traditional interface modification layers and affecting the subsequent preparation of the perovskite active layer, resulting in poor photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell. To solve the above technical problems, the present application provides a perovskite / silicon heterojunction solar cell, as Figure 1As shown, the perovskite / silicon heterojunction solar cell includes a silicon bottom cell 10, a first transparent oxide conductive layer 20, a first carrier transport layer 30, a perovskite active layer 40, a second carrier transport layer 50, a buffer layer 60, a second transparent oxide conductive layer 70, and a metal electrode layer 80, which are sequentially stacked. The perovskite / silicon heterojunction solar cell further includes an interface modification layer 90, which is disposed between the first carrier transport layer 30 and the perovskite active layer 40. The material of the interface modification layer 90 includes a benzodithiophene compound represented by formula (I).

[0042]

[0043] Wherein, R1 is selected from C1-C 16 alkyl, R2 is selected from a halogen atom or C1-C 10 alkyl, R3 and R4 are each independently selected from C1-C8 alkyl, and R5 is selected from C1-C8 alkyl.

[0044] The liquid crystal small molecule of the benzodithiophene compound represented by formula (I) in the present application has a long-range ordered arrangement and good crystallinity, and can play the role of a nucleating agent in the nucleation process of the perovskite active material, and can effectively improve the crystallization quality of the perovskite active layer 40. By providing an interface modification layer 90 containing the benzodithiophene compound represented by formula (I) between the first carrier transport layer 30 and the perovskite active layer 40, the carrier lifetime can be effectively extended, the photocurrent decay time can be shortened, exciton dissociation can be promoted, and charge transport and collection can be facilitated. At the same time, the defects on the surface of the first carrier transport layer 30 can be passivated, thereby improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell.

[0045] In a preferred embodiment, R1 includes but is not limited to C1-C 16 linear or branched alkyl, preferably C8-C 16 branched alkyl; R2 includes but is not limited to a halogen atom or C1-C 10 linear or branched alkyl; R3 and R4 each independently include but are not limited to C1-C8 linear or branched alkyl; R5 includes but is not limited to C1-C8 linear or branched alkyl. The substituents of the benzodithiophene compound represented by formula (I) include but are not limited to the above types. Limiting them within the above range is beneficial to improving the nucleation process of the perovskite active material and the crystallinity of the perovskite active layer 40; at the same time, it is also beneficial to extend the carrier lifetime, shorten the photocurrent decay time, and is beneficial to passivating the defects on the surface of the first carrier transport layer 30, thereby being beneficial to improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell.

[0046] In order to further improve the crystallinity of the perovskite active layer 40, further extend the carrier lifetime, shorten the photocurrent decay time, and further passivate the defects on the surface of the first carrier transport layer 30, thereby further improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell, preferably, R1 includes but is not limited to 2-ethylhexyl, 4-butyloctyl or 6-hexyldecyl, R2 is Cl or n-hexyl, preferably Cl, R3 and R4 each independently include but are not limited to n-hexyl, n-octyl, n-decyl or ethylhexyl, and R5 includes but is not limited to n-hexyl, n-octyl or ethylhexyl.

[0047] In a preferred embodiment, the benzodithiophene compound represented by formula (I) includes but is not limited to any one of the following compounds:

[0048]

[0049] Compared with other types, using the above-mentioned type of compound as the material of the interface modification layer 90 can better play the role of the nucleating agent, which is beneficial to further improving the crystallization quality of the perovskite active layer 40; at the same time, it is beneficial to further extend the carrier lifetime, shorten the photocurrent decay time, promote exciton dissociation, further facilitate the transport and collection of charges, and at the same time is beneficial to further passivate the defects on the surface of the first carrier transport layer 30, thereby being beneficial to further improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell.

[0050] In a preferred embodiment, the thickness of the interface modification layer 90 is 5-15 nm. The thickness of the interface modification layer 90 includes but is not limited to the above range. Limiting it within the above range is beneficial to better play the role of the interface modification layer 90, which is beneficial to further improving the crystallization quality of the perovskite active layer 40; at the same time, it is beneficial to further extend the carrier lifetime, shorten the photocurrent decay time, promote exciton dissociation, further facilitate the transport and collection of charges, and thereby be beneficial to further improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell.

[0051] The perovskite cell part in the perovskite / silicon heterojunction solar cell provided by this application can have a reverse structure (p-i-n structure). In a preferred embodiment, the first carrier transport layer 30 is a hole transport layer, and the second carrier transport layer 50 is an electron transport layer. Compared with the normal structure (n-i-p structure), the perovskite solar cell with a reverse structure has better photoelectric conversion efficiency and stability.

[0052] In order to improve the carrier transport efficiency and at the same time shorten the carrier transport path, thereby improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the thickness of the first carrier transport layer 30 is 1-5 nm.

[0053] In a preferred embodiment, the thickness of the perovskite active layer 40 is 500 - 1000 nm. The thickness of the perovskite active layer 40 includes but is not limited to the above range. Limiting it within the above range is conducive to better playing its role in absorbing sunlight, is conducive to better transporting electrons and holes, and thus is conducive to improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell.

[0054] In order to improve the carrier transport efficiency and shorten the carrier transport path, thereby improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the thickness of the second carrier transport layer 50 is 10 - 30 nm.

[0055] In a preferred embodiment, the thickness of the first transparent oxide conductive layer 20 is 5 - 35 nm. The thickness of the first transparent oxide conductive layer 20 includes but is not limited to the above range. Limiting it within the above range is conducive to better playing its conductivity and is conducive to shortening the electron transport path, thereby being conducive to improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell.

[0056] The setting of the buffer layer 60 can improve the band mismatch between interfaces and reduce the defect density, thereby being able to improve the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell and inhibit the performance degradation. In order to further improve the band mismatch between interfaces and further reduce the defect density, thereby further improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the thickness of the buffer layer 60 is 10 - 30 nm.

[0057] In a preferred embodiment, the material of the buffer layer 60 includes but is not limited to tin dioxide and / or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). Using the buffer layer 60 of the above type is conducive to improving the band mismatch between interfaces and reducing the defect density, thereby improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell.

[0058] The setting of the second transparent oxide conductive layer 70 can improve the carrier transport efficiency, reduce the interface defects, and adjust the energy level structure, thereby being able to improve the photoelectric conversion efficiency and stability of the perovskite / silicon heterojunction solar cell. In order to further improve the carrier transport efficiency and further reduce the interface defects, thereby further improving the photoelectric conversion efficiency and stability of the perovskite / silicon heterojunction solar cell, preferably, the thickness of the second transparent oxide conductive layer 70 is 70 - 110 nm.

[0059] In a preferred embodiment, the thickness of the metal electrode layer 80 is 100 - 150 nm or 10 - 15 μm. The thickness of the metal electrode layer 80 includes but is not limited to the above range. Limiting it within the above range is beneficial to better exert its conductivity, thereby being conducive to improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell.

[0060] HJT cells (intrinsic thin-film heterojunction solar cells) and TOPCon cells (tunnel oxide passivated contact solar cells) have low temperature coefficients, high photoelectric conversion efficiencies, and long service lives. IBC cells (all-back-contact cells) have good compatibility and high photoelectric conversion efficiencies. In a preferred embodiment, the crystalline silicon bottom cell 10 includes but is not limited to HJT cells, TOPCon cells, or IBC cells.

[0061] To further improve the carrier transport efficiency, reduce interface defects, and adjust the energy level structure, thereby further improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the materials of the first transparent oxide conductive layer 20 and the second transparent oxide conductive layer 70 each independently include but are not limited to one or more of the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), and indium zirconium oxide (IZrO).

[0062] To improve the carrier transport efficiency and thus improve the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the material of the first carrier transport layer 30 includes but is not limited to x one or more of the group consisting of NiO, MoO3, V2O5, and CuSCN.

[0063] In a preferred embodiment, the bandgap of the perovskite active layer 40 is 1.60 - 1.70 eV. The bandgap of the perovskite active layer 40 includes but is not limited to the above range. Limiting it within the above range is beneficial to improving the energy level matching, thereby improving the light energy utilization rate and further improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell.

[0064] To further improve the light absorption efficiency and carrier transport efficiency of the perovskite active layer 40, preferably, the material of the perovskite active layer 40 includes but is not limited to ABX3, where A is CH3NH3 + 、NH=CHNH3 + or Cs + ,B is Pb 2+ or Sn 2+ ,X is I - 、Cl - or Br - .

[0065] To improve the carrier transport efficiency and the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the material of the second carrier transport layer 50 includes but is not limited to PCBM (fullerene derivative) and / or C 60 (buckminsterfullerene).

[0066] The material of the metal electrode layer 80 used in this application can be a commonly used metal material in the art. In a preferred embodiment, the material of the metal electrode layer 80 includes but is not limited to one or more of the group consisting of gold, silver, and copper.

[0067] The second aspect of this application also provides a method for manufacturing the above-mentioned perovskite / silicon heterojunction solar cell provided by this application, including sequentially manufacturing a first transparent oxide conductive layer 20, a first carrier transport layer 30, a perovskite active layer 40, a second carrier transport layer 50, a buffer layer 60, a second transparent oxide conductive layer 70, and a metal electrode layer 80 on the surface of the silicon bottom cell 10. The method for manufacturing the perovskite / silicon heterojunction solar cell further includes: manufacturing an interface modification layer 90 on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20. The method for manufacturing the interface modification layer 90 includes: coating a mixed solution containing the benzodithiophene compound shown in formula (I) on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20, and obtaining the interface modification layer 90 after annealing; or, depositing the benzodithiophene compound shown in formula (I) on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20 by evaporation to obtain the interface modification layer 90.

[0068] Compared with the manufacturing method of the traditional perovskite / silicon heterojunction solar cell, the above-mentioned manufacturing method provided by this application further includes the manufacturing of the interface modification layer 90, and the interface modification layer 90 is disposed on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20 by a coating method or an evaporation method. The interface modification layer 90 includes the above-mentioned benzodithiophene compound shown in formula (I) provided by this application. The liquid crystal small molecule of the benzodithiophene compound shown in formula (I) of this application has a long-range ordered arrangement and good crystallinity, and can play the role of a nucleating agent during the nucleation process of the perovskite active material, and can effectively improve the crystallization quality of the perovskite active layer 40. By disposing the interface modification layer 90 on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20, the carrier lifetime can be effectively extended, the photocurrent decay time can be shortened, exciton dissociation can be promoted, the transmission and collection of charges can be facilitated, and at the same time, the defects on the surface of the first carrier transport layer 30 can be passivated, thereby improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell.

[0069] In a preferred embodiment, spin coating, slot die coating or blade coating is used for coating. Compared with other coating methods, the above coating methods are particularly suitable for the preparation of thinner films, facilitating the control of the thickness of the interfacial modification layer 90, and the obtained interfacial modification layer 90 is relatively uniform.

[0070] To further improve the uniformity and film-forming quality of the interfacial modification layer 90, preferably, in the mixed solution, the mass concentration of the benzodithiophene compound shown in formula (I) is 5-10 mg / mL, and the spin coating speed is 3000-5000 rpm.

[0071] To improve the compatibility of the benzodithiophene compound shown in formula (I) with the solvent and enhance its dispersion uniformity in the mixed solution, thus facilitating the subsequent coating process, preferably, the solvent in the mixed solution includes but is not limited to chlorobenzene.

[0072] To further improve the uniformity and film-forming quality of the interfacial modification layer 90, preferably, the temperature of the annealing treatment is 100-150 °C, and the time is 5-15 min.

[0073] Vacuum evaporation is a processing method in which the evaporation source is heated to make it vaporize, and the vaporized particles are deposited on the surface of the substrate to obtain a thin film. In a preferred embodiment, the benzodithiophene compound shown in formula (I) is used as the evaporation source, and the interfacial modification layer 90 is prepared by vacuum evaporation. During the evaporation process, the heating temperature of the evaporation source is 300-600 °C, the vacuum degree is 2×10 -3 ~6×10 -4 Pa, and the evaporation rate is The heating temperature, vacuum degree and treatment time during the evaporation process include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to improving the film-forming quality of the interfacial modification layer 90, enhancing the uniformity of the film layer, thus facilitating the better play of the role of the interfacial modification layer 90, and further being beneficial to improving the photovoltaic performance and stability of the perovskite / silicon heterojunction solar cell.

[0074] Preparing the buffer layer 60 on the surface of the second carrier transport layer 50 away from the perovskite active layer 40 can improve the band gap mismatch between interfaces, reduce the defect density, thereby improving the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell and being beneficial to suppressing performance degradation. To further improve the band gap mismatch between interfaces, reduce the defect density, and at the same time, to improve the film-forming quality and film layer uniformity of the buffer layer 60, and further improve the photoelectric conversion efficiency of the perovskite / silicon heterojunction solar cell, preferably, the buffer layer 60 is prepared by atomic layer deposition (ALD method).

[0075] Depositing a second transparent oxide conductive layer 70 on the surface of the buffer layer 60 away from the second carrier transport layer 50 can improve the carrier transport efficiency, reduce interface defects, and adjust the energy level structure, thereby improving the photoelectric conversion efficiency and stability of the perovskite / silicon heterojunction solar cell. To further improve the film-forming quality and uniformity of the second transparent oxide conductive layer 70, and further improve the carrier transport efficiency, and thus further improve the photoelectric conversion efficiency and stability of the perovskite / silicon heterojunction solar cell, preferably, the second transparent oxide conductive layer 70 is prepared by magnetron sputtering.

[0076] In a preferred embodiment, the first transparent oxide conductive layer 20 is prepared by sputtering; the perovskite active layer 40 is prepared by a one-step or two-step method; the first carrier transport layer 30 is prepared by spin coating or evaporation; the second carrier transport layer 50 is prepared by thermal evaporation; the metal electrode layer 80 is prepared by vacuum evaporation or screen printing.

[0077] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0078] Example 1

[0079] A method for preparing a perovskite / silicon heterojunction solar cell, comprising:

[0080] (1) Using an HJT cell produced by Zhejiang Aikosolar Technology Co., Ltd. as the silicon heterojunction bottom cell 10;

[0081] (2) Preparing the first transparent oxide conductive layer 20:

[0082] Depositing an ITO conductive layer with a thickness of 10 nm on the surface of the pn junction of the silicon heterojunction bottom cell 10 obtained in step (1) by sputtering.

[0083] (3) Preparing the first carrier transport layer 30 (hole transport layer):

[0084] Preparing a NiO layer on the surface of the ITO conductive layer away from the silicon heterojunction bottom cell 10 obtained in step (2) by magnetron sputtering, and the thickness of the NiO layer is 30 nm; x layer x The thickness of the layer is 30 nm;

[0085] (4) Preparing the interface modification layer 90:

[0086] Preparing Compound 1 (purchased from J&K Scientific, CAS No. 2041283-06-9), and the chemical structural formula of the Compound 1 is as follows:

[0087]

[0088] Mix 5 mg of Compound 1 with 1 mL of chlorobenzene to obtain a mixed solution with a mass concentration of 5 mg / mL. Spin-coat the mixed solution on the surface of the NiO layer prepared in step (3) x facing away from the ITO conductive layer. During the spin-coating process, the rotation speed is 3000 rpm and the time is 30 s. After spin-coating, heat-treat at 100 °C for 5 min to obtain an interfacial modification layer 90 with a thickness of 5 nm.

[0089] (5) Prepare the perovskite active layer 40:

[0090] Disperse PbI2, PbBr2, CsI, FAI, and MABr in a mixed solvent of DMF and DMSO (the volume ratio of DMF to DMSO is 9:1) to obtain a perovskite precursor solution. Use the spin-coating method to prepare the perovskite active layer 40 on the surface of the interfacial modification layer 90 prepared in step (4) x facing away from the NiO layer. First, spin-coat at a rotation speed of 1500 rpm for 5 s, and then spin-coat at a rotation speed of 3000 rpm for 25 s. Five seconds before the end of the spin-coating process, drop 200 μL of chlorobenzene into the center of the substrate. After spin-coating stops, immediately transfer the substrate to a heating plate at 100 °C and anneal for 15 min to obtain a Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.75 Br 0.25 )3 layer with a thickness of 700 nm.

[0091] (6) Prepare the second carrier transport layer 50 (electron transport layer):

[0092] Use thermal evaporation to prepare a C layer with a thickness of 20 nm on the surface of the Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.75 Br 0.25 )3 layer facing away from the interfacial modification layer 90. 60 layer;

[0093] (7) Prepare the buffer layer 60:

[0094] On the surface of the C layer prepared in step (6) facing away from the perovskite active layer 40, prepare a SnO2 layer with a thickness of 20 nm by atomic layer deposition. 60

[0095] (8) Prepare the second transparent oxide conductive layer 70:

[0096] A layer of ITO conductive layer is deposited on the surface of the SnO2 layer prepared in step (7) away from the electron transport layer by sputtering method, and the thickness of the ITO conductive layer is 100 nm;

[0097] (9) Preparation of the metal electrode layer 80:

[0098] Using the vacuum thermal deposition method, an Ag electrode with a thickness of 110 nm is deposited on the surface of the second transparent oxide conductive layer 70.

[0099] The stacked structure of the perovskite / silicon heterojunction solar cell prepared in this example is as Figure 1 shown.

[0100] Example 2

[0101] The difference from Example 1 is that Compound 1 in step (4) is replaced by Compound 2 (purchased from J&K Scientific, catalog number OS0136), and the chemical structure of Compound 2 is as follows:

[0102]

[0103] Example 3

[0104] The difference from Example 1 is that in step (4), the mass concentration of the mixed solution obtained by mixing Compound 1 and chlorobenzene is 10 mg / mL, and the thickness of the prepared interface modification layer 90 is 15 nm.

[0105] Example 4

[0106] The difference from Example 1 is that in step (4), the mass concentration of the mixed solution obtained by mixing Compound 1 and chlorobenzene is 1 mg / mL, and the thickness of the prepared interface modification layer 90 is 3 nm.

[0107] Example 5

[0108] The difference from Example 1 is that in step (4), Compound 1 is used as the evaporation source, and the interface modification layer 90 is prepared by vacuum evaporation. During the evaporation process, the heating temperature of the evaporation source is 600 °C, the vacuum degree is 6×10 -4 Pa, and the evaporation rate is

[0109] Example 6

[0110] The difference from Example 1 is that in step (4), Compound 1 is used as the evaporation source, and the interface modification layer 90 is prepared by vacuum evaporation. During the evaporation process, the heating temperature of the evaporation source is 300 °C, the vacuum degree is 2×10 -3 Pa, and the evaporation rate is

[0111] Example 7

[0112] The difference from Example 1 is that in step (4), compound 1 is used as the evaporation source, and the interfacial modification layer 90 is prepared by vacuum evaporation. During the evaporation process, the heating temperature of the evaporation source is 600 °C, the vacuum degree is 6×10 -4 Pa, and the evaporation rate is

[0113] Comparative Example 1

[0114] The difference from Example 1 is that step (4) is omitted, and the prepared perovskite / crystalline silicon tandem solar cell does not include the interfacial modification layer 90.

[0115] Photovoltaic performance tests were carried out on the perovskite / crystalline silicon tandem solar cell devices prepared in all the above examples and comparative examples of the present application. The effective area of the devices was 100 mm 2 ; The test conditions were as follows: spectral distribution AM1.5G, light intensity 100 mW / cm 2 , a solar simulator (Julight Optoelectronic Technology Co., Ltd.), and the J-V curve was measured using a Keithley 2400. The results are shown in Table 1 below.

[0116] Table 1

[0117]

[0118] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: Compared with the preparation method of traditional perovskite / crystalline silicon tandem solar cells, the above preparation method of the present application also includes the preparation of the interfacial modification layer 90. The interfacial modification layer 90 is disposed on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20 by a coating method or an evaporation method. The interfacial modification layer 90 includes the benzodithiophene compound shown in the above formula (I) provided by the present application. The liquid crystal small molecule of the benzodithiophene compound shown in formula (I) of the present application has a long-range ordered arrangement and good crystallinity, and can play the role of a nucleating agent during the nucleation process of the perovskite active material, and can effectively improve the crystallization quality of the perovskite active layer 40. By disposing the interfacial modification layer 90 on the surface of the first carrier transport layer 30 away from the first transparent oxide conductive layer 20, the carrier lifetime can be effectively extended, the photocurrent decay time can be shortened, exciton dissociation can be promoted, the transmission and collection of charges can be facilitated, and at the same time, the defects on the surface of the first carrier transport layer 30 can be passivated, thereby improving the photovoltaic performance and stability of the perovskite / crystalline silicon tandem solar cell.

[0119] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented, for example, in an order other than those described here.

[0120] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A perovskite / crystalline silicon tandem solar cell, comprising a crystalline silicon bottom cell (10), a first transparent oxide conductive layer (20), a first carrier transport layer (30), a perovskite active layer (40), a second carrier transport layer (50), a buffer layer (60), a second transparent oxide conductive layer (70) and a metal electrode layer (80) which are sequentially stacked, characterized in that, The perovskite / silicon heterojunction solar cell further includes an interfacial modification layer (90), the interfacial modification layer (90) is disposed between the first carrier transport layer (30) and the perovskite active layer (40), and the material of the interfacial modification layer (90) includes a benzodithiophene compound represented by formula (I). Among them, R1 is selected from C1-C 16 alkyl groups, R2 is selected from halogen atoms or C1-C 10 alkyl groups, R3 and R4 are each independently selected from C1-C8 alkyl groups, and R5 is selected from C1-C8 alkyl groups.

2. The perovskite / silicon heterojunction tandem solar cell according to claim 1, wherein, The R1 is selected from linear or branched alkyl groups having C1 to C 16 , preferably branched alkyl groups having C8 to C 16 , more preferably 2-ethylhexyl, 4-butyloctyl or 6-hexyldecyl; The R2 is selected from a halogen atom or a linear or branched alkyl group having 1 to C 10 Preferably, it is Cl or n-hexyl, and more preferably Cl; R3 and R4 are each independently selected from straight-chain or branched-chain alkyl groups having 1 to 8 carbon atoms, preferably n-hexyl, n-octyl, n-decyl or 2-ethylhexyl; R5 is selected from straight-chain or branched-chain alkyl groups having 1 to 8 carbon atoms, preferably n-hexyl, n-octyl or 2-ethylhexyl.

3. The perovskite / silicon heterojunction solar cell according to claim 1, wherein The benzodithiophene compound represented by formula (I) is selected from any one of the following compounds:

4. The perovskite / silicon heterojunction tandem solar cell according to any one of claims 1 to 3, characterized in that, The thickness of the interfacial modification layer (90) is 5 to 15 nm; Preferably, the first carrier transport layer (30) is a hole transport layer, and the second carrier transport layer (50) is an electron transport layer; Preferably, the thickness of the first carrier transport layer (30) is 1 to 5 nm; and / or, the thickness of the perovskite active layer (40) is 500 to 1000 nm; and / or, the thickness of the second carrier transport layer (50) is 10 to 30 nm; and / or, the thickness of the first transparent oxide conductive layer (20) is 5 to 35 nm; and / or, the thickness of the buffer layer (60) is 10 to 30 nm; and / or, the thickness of the second transparent oxide conductive layer (70) is 70 to 110 nm; and / or, the thickness of the metal electrode layer (80) is 100 to 150 nm or 10 to 15 μm.

5. The perovskite / silicon heterojunction tandem solar cell according to claim 4, wherein The crystalline silicon bottom cell (10) is selected from HJT cells, TOPCon cells or IBC cells; Preferably, the materials of the first transparent oxide conductive layer (20) and the second transparent oxide conductive layer (70) are each independently selected from one or more of the group consisting of indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide and indium zirconium oxide; Preferably, the material of the first carrier transport layer (30) is selected from one or more of the group consisting of NiO x , MoO3, V2O5, and CuSCN; Preferably, the band gap of the perovskite active layer (40) is 1.60 to 1.70 eV, and preferably the material of the perovskite active layer (40) is selected from ABX3, wherein A is CH3NH3 + , NH=CHNH3 + or Cs + , B is Pb 2+ or Sn 2+ , X is I - , Cl - or Br - ; Preferably, the material of the second charge carrier transport layer (50) is selected from PCBM and / or C 60 ; Preferably, the material of the buffer layer (60) is selected from tin dioxide and / or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; Preferably, the material of the metal electrode layer (80) is selected from one or more of the group consisting of gold, silver and copper.

6. A method for preparing a perovskite / silicon heterojunction solar cell according to any one of claims 1 to 5, comprising sequentially preparing a first transparent oxide conductive layer (20), a first carrier transport layer (30), a perovskite active layer (40), a second carrier transport layer (50), a buffer layer (60), a second transparent oxide conductive layer (70), and a metal electrode layer (80) on the surface of a silicon bottom cell (10), characterized in that, The method for preparing the perovskite / silicon heterojunction solar cell further includes: preparing an interfacial modification layer (90) on a surface of the first carrier transport layer (30) away from the first transparent oxide conductive layer (20), and the method for preparing the interfacial modification layer (90) includes: Coating a mixed solution containing the benzodithiophene compound represented by formula (I) on a surface of the first carrier transport layer (30) away from the first transparent oxide conductive layer (20), and obtaining the interfacial modification layer (90) after annealing treatment; or, Depositing the benzodithiophene compound represented by formula (I) on a surface of the first carrier transport layer (30) away from the first transparent oxide conductive layer (20) by evaporation deposition to obtain the interfacial modification layer (90).

7. The preparation method of the perovskite / silicon heterojunction tandem solar cell according to claim 6, wherein The coating is performed by spin coating, slot die coating or blade coating; Preferably, in the mixed solution, the mass concentration of the benzodithiophene compound represented by the formula (I) is 5 to 10 mg / mL, and the preferred spin coating speed is 3000 to 5000 rpm; Preferably, the solvent in the mixed solution is selected from chlorobenzene.

8. The manufacturing method of the perovskite / silicon heterojunction tandem solar cell according to claim 7, characterized in that, The temperature of the annealing treatment is 100 to 150 °C, and the time is 5 to 15 min.

9. The preparation method of the perovskite / crystalline silicon tandem solar cell according to claim 6, wherein, Using the benzodithiophene compound represented by the formula (I) as an evaporation source, the interface modification layer (90) is prepared by vacuum evaporation. During the evaporation process, the heating temperature of the evaporation source is 300 to 600 °C, the vacuum degree is 2×10 -3 ~6×10 -4 Pa, and the evaporation rate is 10. The method for preparing a perovskite / silicon heterojunction solar cell according to any one of claims 6 to 9, wherein the buffer layer (60) is prepared by atomic layer deposition; Preferably, the second transparent oxide conductive layer (70) is prepared by magnetron sputtering.

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