Perovskite solar cell and preparation method thereof

Abstract

The invention provides a perovskite solar cell and a preparation method thereof. The preparation method comprises the steps of providing a transparent conductive layer, and forming a hole transport layer on one side of the transparent conductive layer; forming a self-assembly molecular layer on one side, far away from the transparent conductive layer, of the hole transport layer; a perovskite thin film is formed on the side, away from the hole transport layer, of the self-assembly molecular layer, the perovskite thin film is wrapped with a steam cover, and the perovskite thin film is provided with first cations located at the A site; a vapor compound containing halide ions and second cations is introduced into the steam cover through a first channel of the steam cover, so that part of perovskite crystals in the perovskite thin film and the vapor compound are subjected to a replacement reaction to form a perovskite light absorption layer, the replacement reaction is used for replacing first cations in part of the perovskite crystals with second cations, and the ion radius of the second cations is larger than that of the first cations; and removing the steam cover, and forming an electron transport layer on one side, far away from the self-assembly molecular layer, of the perovskite light absorption layer.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cells, and in particular to a method for preparing a perovskite solar cell, a perovskite solar cell and a stacked cell. Background Art

[0002] With the rapid development of the photovoltaic field, perovskite solar cells have become a typical representative of the new generation of photovoltaic power generation technology. Their advantages such as simple preparation process, diverse processing methods, low cost and high performance have attracted more and more attention, and their band gap is adjustable, which is significantly different from traditional crystalline silicon materials. At present, the efficiency of single-cell perovskite solar cells has increased from 3.8% to 26.1%, which is very close to the photoelectric conversion efficiency record of crystalline silicon solar cells, showing great industrialization potential.

[0003] However, the film defects of the perovskite light-absorbing layer of the perovskite solar cell have long restricted the photoelectric conversion efficiency and device stability of the perovskite solar cell. In order to solve the above problems, the prior art usually adopts targeted passivation strategies from component engineering, interface engineering and additive engineering to alleviate the impact of film defects on the photoelectric conversion efficiency and device stability of perovskite solar cells. However, the passivated materials in the current component engineering, interface engineering and additive engineering cannot achieve good coordination and interaction with the perovskite light-absorbing layer, and the passivation effect of the film defects of the perovskite light-absorbing layer is not ideal, which still cannot affect the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0004] Therefore, a new preparation process is urgently needed to solve the problems of low photoelectric conversion efficiency and poor stability of perovskite solar cells caused by thin film defects in the perovskite light-absorbing layer. Summary of the invention

[0005] The main purpose of the present invention is to provide a preparation process of a perovskite solar cell, a perovskite solar cell and a stacked cell to solve the problems of low photoelectric conversion efficiency and poor stability of perovskite solar cells caused by thin film defects of the perovskite light absorbing layer in the prior art.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing a perovskite solar cell is provided, comprising: providing a transparent conductive layer, forming a hole transport layer on one side of the transparent conductive layer; forming a self-assembled molecular layer on a side of the hole transport layer away from the transparent conductive layer; forming a perovskite film on a side of the self-assembled molecular layer away from the hole transport layer, and wrapping the perovskite film with a steam hood, the steam hood having a first channel connected to the outside, and the perovskite film having a first cation located at the A position; passing a vaporous compound containing halogen ions and a second cation into the steam hood through the first channel, so that part of the perovskite crystals in the perovskite film undergo a substitution reaction with the vaporous compound to form a perovskite light-absorbing layer, wherein the substitution reaction is used to replace the first cation in part of the perovskite crystals with a second cation, and the ionic radius of the second cation is greater than the ionic radius of the first cation; removing the steam hood, and forming an electron transport layer on the side of the perovskite light-absorbing layer away from the self-assembled molecular layer.

[0007] Optionally, the steam hood has a second channel connected to the outside, and the method further includes: after the step of forming the perovskite light absorbing layer and before the step of removing the steam hood, passing an inert gas into the steam hood through the first channel, so that the inert gas removes the gaseous compounds that do not participate in the replacement reaction from the steam hood through the second channel.

[0008] Optionally, the step of forming a self-assembled molecular layer includes: mixing isoalkylammonium hydrochloride and self-assembled molecules in the self-assembled molecular layer in a preset ratio to obtain a mixed solution; coating the mixed solution on a side of the hole transport layer away from the transparent conductive layer to form a wet film containing isoalkylammonium hydrochloride and self-assembled molecules; and heat-treating the wet film to form a self-assembled molecular layer.

[0009] Alternatively, the isoalkylammonium hydrochloride is 6-(iodo-5-azaalkyl)acetic acid.

[0010] Optionally, the self-assembled molecules in the self-assembled molecular layer include one of the following: a (2-(9H-carbazole-9-yl)ethyl)phosphonic acid layer, a [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid layer, a [4-(3,6-dimethyloxy-9H-carbazole-9-yl)butyl]phosphonic acid layer and methoxy-4-phenyl-1,2-propanedione.

[0011] Optionally, the step of forming a perovskite film includes: forming a perovskite precursor film on a side of the self-assembled molecular layer away from the hole transport layer; heat treating the perovskite precursor film to form a perovskite film, wherein the heat treatment temperature is less than or equal to 100°C.

[0012] Optionally, the first cation is a methylamine ion (MA+) and the second cation is a guanidine ion (GA+).

[0013] Optionally, the hole transport layer is a nickel oxide layer.

[0014] According to another aspect of the present invention, a perovskite solar cell is provided, comprising: a hole transport layer located on one side of a transparent conductive layer; a self-assembled molecular layer located on a side of the hole transport layer away from the transparent conductive layer; a perovskite light absorption layer located on a side of the self-assembled molecular layer away from the hole transport layer, the perovskite light absorption layer having cations located at the A position, the cations comprising a first cation and a second cation, the first cation and the second cation having different ionic radii; and an electron transport layer located on a side of the perovskite light absorption layer away from the self-assembled molecular layer.

[0015] Optionally, the self-assembled molecular layer has a plurality of different functional groups, including methoxy groups, phosphonic acid groups and carboxyl groups.

[0016] Optionally, the perovskite solar cell further includes: a first electrode layer, located on a side of the hole transport layer away from the self-assembled molecular layer; and a second electrode layer, located on a side of the electron transport layer away from the perovskite light absorbing layer.

[0017] According to another aspect of the present invention, there is provided a stacked cell comprising a crystalline silicon cell and any one of the above-mentioned perovskite solar cells.

[0018] The technical solution of the present invention is applied to provide a method for preparing a perovskite solar cell, the method comprising first forming a hole transport layer on one side of a provided transparent conductive layer, then forming a self-assembled molecular layer on the side of the hole transport layer away from the transparent conductive layer, and then forming a perovskite light absorption layer on the side of the self-assembled molecular layer away from the hole transport layer. The self-assembled molecular layer can not only adjust the energy level at the interface between the hole transport layer and the perovskite light absorption layer to improve the energy level matching between the hole transport layer and the perovskite light absorption layer; it can also enhance the adhesion between the hole transport layer and the perovskite light absorption layer to reduce defects and instability at the interface, thereby achieving the effect of promoting the effective transmission of holes and reducing energy loss. Further, in the step of forming the above-mentioned perovskite light-absorbing layer, the embodiment of the present application first forms a perovskite film ABX3, A is a first cation, and then after the perovskite film is wrapped with a steam hood, a gaseous compound containing halogen ions and a second cation is passed into the steam hood through the first channel of the steam hood, so that part of the perovskite crystals in the perovskite film undergo a substitution reaction with the gaseous compound (that is, the first cation at the A position in part of the perovskite film ABX3 is replaced with a second cation), and finally a perovskite light-absorbing layer is formed. Wherein, since the ionic radius of the above-mentioned second cation is greater than the ionic radius of the first cation, the film quality after the substitution reaction is more dense and uniform than the film quality of the perovskite film, thereby obtaining a perovskite light-absorbing layer with a more stable skeleton. And then after the electron transport layer is formed on the side of the perovskite light-absorbing layer away from the self-assembled molecular layer, a perovskite solar cell with better performance can be obtained, thereby solving the problem of low photoelectric conversion efficiency and poor stability of the perovskite solar cell caused by the film defects of the perovskite light-absorbing layer in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention 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 accompanying drawings:

[0020] Figure 1 A schematic structural diagram of a perovskite solar cell according to an embodiment of the present invention is shown.

[0021] The above drawings include the following reference numerals:

[0022] 10. First electrode layer; 20. Hole transport layer; 30. Self-assembled molecular layer; 40. Perovskite light absorption layer; 50. Electron transport layer; 60. Second electrode layer. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention 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 accompanying drawings and in combination with the embodiments.

[0024] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] As described in the background technology, in the prior art, the film defects of the perovskite light-absorbing layer of the perovskite solar cell have long restricted the photoelectric conversion efficiency and device stability of the perovskite solar cell. In order to solve the above problems, the prior art usually adopts a targeted passivation strategy from component engineering, interface engineering and additive engineering to alleviate the impact of film defects on the photoelectric conversion efficiency and device stability of the perovskite solar cell. However, the passivated materials in the current component engineering, interface engineering and additive engineering cannot achieve good coordination and interaction with the perovskite light-absorbing layer, and the passivation effect of the film defects of the perovskite light-absorbing layer is not ideal, which still cannot affect the photoelectric conversion efficiency and stability of the perovskite solar cell. In order to solve the problem of low photoelectric conversion efficiency and poor stability of the perovskite solar cell caused by the film defects of the perovskite light-absorbing layer, the embodiments of the present application provide a method for preparing a perovskite solar cell, a perovskite solar cell and a stacked cell.

[0027] In some optional embodiments, a method for preparing a perovskite solar cell is provided, the method comprising: providing a transparent conductive layer, forming a hole transport layer on one side of the transparent conductive layer; forming a self-assembled molecular layer on a side of the hole transport layer away from the transparent conductive layer; forming a perovskite film on a side of the self-assembled molecular layer away from the hole transport layer, and wrapping the perovskite film with a steam hood, the steam hood having a first channel connected to the outside, the perovskite film having a first cation located at the A position; passing a vaporous compound containing halogen ions and a second cation into the steam hood through the first channel, so that part of the perovskite crystals in the perovskite film undergo a substitution reaction with the vaporous compound to form a perovskite light-absorbing layer, wherein the substitution reaction is used to replace the first cation in the part of the perovskite crystals with the second cation, the ionic radius of the second cation being greater than the ionic radius of the first cation; removing the steam hood, and forming an electron transport layer on a side of the perovskite light-absorbing layer away from the self-assembled molecular layer.

[0028] It is explained here that since the perovskite light-absorbing layer is obtained by a substitution reaction between part of the perovskite crystals in the perovskite film and the above-mentioned gaseous compound, the perovskite crystals in the above-mentioned perovskite light-absorbing layer in the embodiment of the present application may include a first perovskite crystal and a second perovskite crystal, wherein the first perovskite crystal is a perovskite crystal before the substitution reaction occurs, and the perovskite crystal does not contain the second cation in the above-mentioned gaseous compound; the second perovskite crystal is a perovskite crystal after the substitution reaction occurs, and the perovskite crystal contains the second cation in the above-mentioned gaseous compound.

[0029] Specifically, the material of the electron transport layer may include, but is not limited to, tin oxide (SnO2), zinc oxide (ZnO), titanium oxide (TiO2), fullerene derivatives (PCBM) and C 60 .

[0030] In the above preparation method, since the self-assembled molecular layer can not only adjust the energy level at the interface to improve the energy level matching between the film layers; it can also enhance the adhesion between the film layers to reduce the defects and instability at the interface. Therefore, in the embodiment of the present application, after the hole transport layer is formed, the self-assembled molecular layer is first formed, and then the perovskite light absorption layer is formed on the side of the self-assembled molecular layer away from the hole transport layer, thereby not only improving the energy level matching between the hole transport layer and the perovskite light absorption layer, but also reducing the defects and instability at the interface between the hole transport layer and the perovskite light absorption layer, thereby achieving the effect of promoting the effective transmission of holes and reducing energy loss. Further, in the step of forming the above-mentioned perovskite light-absorbing layer, the embodiment of the present application first forms a perovskite film ABX3, A is a first cation, and then after the perovskite film is wrapped with a steam hood, a gaseous compound containing halogen ions and a second cation is passed into the steam hood through the first channel of the steam hood, so that part of the perovskite crystals in the perovskite film undergo a substitution reaction with the gaseous compound (that is, the first cation at the A position in part of the perovskite film ABX3 is replaced with a second cation), and finally a perovskite light-absorbing layer is formed. Wherein, since the ionic radius of the above-mentioned second cation is greater than the ionic radius of the first cation, the film quality after the substitution reaction is more dense and uniform than the film quality of the perovskite film, thereby obtaining a perovskite light-absorbing layer with a more stable skeleton. And then after the electron transport layer is formed on the side of the perovskite light-absorbing layer away from the self-assembled molecular layer, a perovskite solar cell with better performance can be obtained, thereby solving the problem of low photoelectric conversion efficiency and poor stability of the perovskite solar cell caused by the film defects of the perovskite light-absorbing layer in the prior art.

[0031] Optionally, before the step of forming the hole transport layer, the method for preparing the perovskite solar cell may further include: forming a transparent conductive layer on one side of the transparent conductive layer so that the transparent conductive layer is located between the transparent conductive layer and the hole transport layer. Exemplarily, the material of the transparent conductive layer may include but is not limited to indium tin oxide (ITO), fluorinated tin oxide (FTO), indium zinc oxide (IZO) and aluminum zinc oxide (AZO).

[0032] Optionally, after the step of forming the electron transport layer, the method for preparing the perovskite solar cell may further include: forming a metal electrode layer on a side of the electron transport layer away from the perovskite light absorbing layer. Exemplarily, the material of the metal electrode layer may include but is not limited to gold (Au), silver (Ag), copper (Cu) and aluminum (Al).

[0033] In some optional embodiments, the steam hood has a second channel connected to the outside, and the method further comprises: after the step of forming the perovskite light absorbing layer and before the step of removing the steam hood, passing an inert gas into the steam hood through the first channel, so that the inert gas removes the gaseous compound that does not participate in the replacement reaction from the steam hood through the second channel. Exemplarily, the inert gas may be nitrogen.

[0034] In the above embodiment, considering that the film layer in which the A ions in ABX3 include multiple cations with different ionic radii can optimize the performance of the perovskite solar cell compared to the film layer in which the A ions in ABX3 are only a single cation, it is only necessary to replace the A-position cations of some perovskite crystals in the perovskite film from the first cation to the second cation. On this basis, after the replacement reaction occurs for a preset time to form a perovskite light-absorbing layer, the excess vapor compounds containing halogen ions and the second cation in the steam hood can be blown away, thereby avoiding the problem that the film quality of the perovskite light-absorbing layer is not improved due to excessive reaction of the replacement reaction. It can be understood that the above-mentioned preset time can be reasonably selected according to the actual needs of those skilled in the art, and the embodiments of the present application are not specifically limited.

[0035] It should be noted that the area of ​​the steam hood can be larger than tens of square centimeters or even hundreds of square centimeters. Therefore, the method for preparing a perovskite solar cell in the embodiment of the present application can realize the preparation of a large-area perovskite solar cell.

[0036] Optionally, the steam hood may also be a cavity. That is, after a perovskite film is formed on the side of the self-assembled molecular layer away from the hole transport layer, the perovskite film may be placed in a cavity, and a vapor compound containing halogen ions and a second cation is introduced into the cavity to allow the vapor compound to undergo a replacement reaction with a portion of the perovskite crystals in the perovskite film, and after the replacement reaction occurs for a preset time to form a perovskite light absorbing layer, the excess vapor compound in the cavity is blown away to prevent the replacement reaction from overreacting and affecting the film quality of the perovskite light absorbing layer.

[0037] In some optional embodiments, the step of forming the self-assembled molecular layer includes: mixing isoalkylammonium hydrochloride and the self-assembled molecules in the self-assembled molecular layer in a preset ratio to obtain a mixed solution; coating the mixed solution on a side of the hole transport layer away from the transparent conductive layer to form a wet film containing the isoalkylammonium hydrochloride and the self-assembled molecules; and heat-treating the wet film to form the self-assembled molecular layer.

[0038] In the above embodiment, since the ammonium end group of isoalkylammonium hydrochloride (IAHA) can coordinate with the perovskite crystals in the perovskite light absorbing layer through ionic interaction, it plays a role in passivating the surface of the perovskite light absorbing layer. Therefore, when forming the above self-assembled molecular layer, the above isoalkylammonium hydrochloride (IAHA) can be used as the second component of the self-assembled molecular layer in addition to the self-assembled molecules.

[0039] It can be seen that the embodiment of the present application forms the above-mentioned self-assembled molecular layer on the side of the hole transport layer away from the transparent conductive layer. Since the components in the self-assembled molecular layer include self-assembled molecules and isoalkylammonium hydrochloride (IAHA), the isoalkylammonium hydrochloride (IAHA) can modify the self-assembled molecular layer, so that the energy level of the transparent conductive layer of the self-assembled molecular layer (which can be a transparent conductive layer with a hole transport layer) can be fine-tuned, so that the transparent conductive layer of the self-assembled molecular layer can show better energy level alignment, which is beneficial to the hole selection at the interface.

[0040] In addition, in the embodiment of the present application, when the self-assembled molecular layer including self-assembled molecules and isoalkylammonium hydrochloride (IAHA) is formed on the side of the hole transport layer away from the transparent conductive layer, since the isoalkylammonium hydrochloride (IAHA) also contains alkyl insulating filler molecules, the alkyl insulating filler molecules can make the self-assembled molecular layer have better coverage, so that for the case where the film deposition of the transparent conductive layer and the hole transport layer with large surface roughness is poor, the self-assembled molecular layer can further avoid the problem of leakage current at the interface.

[0041] Among them, for the preset ratio of isoalkylammonium hydrochloride and self-assembling molecules in the above-mentioned self-assembled molecular layer, those skilled in the art can reasonably select the ratio according to actual needs, and the embodiments of the present application do not make specific limitations.

[0042] Specifically, the isoalkylammonium hydrochloride may be 6-(iodo-5-azaalkyl)acetic acid.

[0043] Specifically, the self-assembled molecules in the above-mentioned self-assembled molecular layer can include one of the following: (2-(9H-carbazole-9-yl)ethyl)phosphonic acid layer (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid layer (MeO-2PACz), [4-(3,6-dimethyloxy-9H-carbazole-9-yl)butyl]phosphonic acid layer (Me-4PACz) and methoxy-4-phenyl-1,2-propanedione (MeO-4PADBC).

[0044] Among them, when the self-assembled molecules in the self-assembled molecular layer are [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid layer (MeO-2PACz), [4-(3,6-dimethyloxy-9H-carbazole-9-yl)butyl]phosphonic acid layer (Me-4PACz) and methoxy-4-phenyl-1,2-propanedione (MeO-4PADBC), since the self-assembled molecules also have methoxy groups, in the process of forming a perovskite light absorption layer on the side of the self-assembled molecular layer away from the hole transport layer, the methoxy group can also serve as an effective ligand for perovskite, thereby improving the wettability of the transparent conductive layer of the perovskite light absorption layer (which can be a transparent conductive layer having the above-mentioned hole transport layer and the self-assembled molecular layer), so that the transparent conductive layer of the perovskite light absorption layer shows better energy level alignment, which is beneficial to the extraction of holes.

[0045] In some optional embodiments, the step of forming the above-mentioned perovskite film may include: forming a perovskite precursor film on a side of the above-mentioned self-assembled molecular layer away from the above-mentioned hole transport layer; heat-treating the above-mentioned perovskite precursor film to form the above-mentioned perovskite film, wherein the temperature of the above-mentioned heat treatment is less than or equal to 100°C.

[0046] Specifically, the perovskite crystals in the above perovskite film can be MAPbI3. Since MAPbI3 is sensitive to temperature, this embodiment can select a relatively low annealing temperature (100°C) to anneal the perovskite precursor film to reduce the damage of the temperature to the perovskite film. Furthermore, in the embodiment of the present application, after the perovskite film is wrapped with a steam hood, a vapor compound containing halogen ions and a second cation is introduced into the steam hood through the first channel of the steam hood, so that part of the perovskite crystals in the perovskite film can undergo a substitution reaction with the vapor compound to form a perovskite light-absorbing layer with a denser and more uniform film quality and a more stable skeleton. That is, the substitution reaction in the embodiment of the present application further compensates for the problem that the film quality of the perovskite film is poor due to the low temperature of the heat treatment.

[0047] Specifically, the first cation may be a methylammonium ion (MA+), and the second cation may be a guanidine ion (GA+). Specifically, the vapor compound may be guanidine bromide (GABr), so that the perovskite crystals in the perovskite light absorbing layer may include MAPbI3 and GAPbI3.

[0048] In some optional embodiments, the hole transport layer is a nickel oxide layer.

[0049] In the above-mentioned embodiment, when the hole transport layer is a nickel oxide layer, the embodiment of the present application also forms a self-assembled molecular layer on the side of the nickel oxide layer away from the transparent conductive layer. Since the self-assembled molecules in the self-assembled molecular layer can form coordination bonds or covalent bonds with the metal ions in the nickel oxide, the surface roughness of the nickel oxide layer can be effectively reduced. In the process of forming a perovskite film on the side of the self-assembled molecular layer away from the nickel oxide layer, the perovskite in the perovskite precursor film can be made to interact more strongly with the self-assembled molecules in the self-assembled molecular layer, which helps to promote the growth and crystallization of perovskite crystals in the perovskite precursor film to form a more uniform perovskite film. Afterwards, the perovskite film is wrapped with a steam hood, and the gaseous compound containing halogen ions and the second cation is passed into the steam hood through the first channel of the steam hood, so that part of the perovskite crystals in the perovskite film undergo a substitution reaction with the gaseous compound, and a perovskite light-absorbing layer with a denser and more uniform film quality and a more stable skeleton can be finally formed.

[0050] In other optional embodiments, the material of the above-mentioned hole transport layer may also include but is not limited to spiro-dioxymethyltriphenylamine (Spiro-OMeTAD), poly(terephthalate) (PTAA), poly(3,4-ethylenedioxythiophene):poly(4-phenylethane sulfonic acid) (PEDOT:PSS).

[0051] The following provides a specific preparation process of a perovskite solar cell, including:

[0052] S1. Provide a transparent conductive layer, and form a transparent conductive layer (ITO) with a thickness of 15 nm on one side of the transparent conductive layer, wherein the transparent conductive layer (ITO) can be obtained by magnetron sputtering deposition in an Ar / O2 mixed atmosphere. Then, the transparent conductive layer having the transparent conductive layer can be cleaned with deionized water, acetone and IPA in sequence for 30 minutes.

[0053] S2, nickel oxide (NiO x ) is sputtered onto the side of the transparent conductive layer (ITO) away from the transparent conductive layer. The sputtering process is carried out for 10 minutes at room temperature, a strong pressure of 0.37 Pa, a radio frequency power of 90 W, and an argon gas flow rate of 20 sccm, thereby forming a hole transport layer with a thickness of 30 nm.

[0054] S3. First, (1-1.5) mg / ml methoxy-4-phenyl-1,2-propanedione (MeO-4PADBC) and (1-1.5) mg / ml 6-(iodo-5λ-azaalkyl)acetic acid were mixed in a ratio of 7:3 and stirred for 15 minutes. Then, 50 μl of the mixed solution was dropped on the side of the hole transport layer away from the transparent conductive layer (ITO), spin-coated at 3000 rpm / 30s, and then annealed on a heating table at 100°C for 15 minutes to obtain a self-assembled molecular layer.

[0055] S4. First, MAPbI3 is prepared by spin coating on the side of the self-assembled molecular layer away from the hole transport layer. After preparation, it is annealed on a heating table at 100°C. Then, a steam hood is used to cover the MAPbI3. There is a channel opening on both sides of the steam hood. First, the right channel opening is closed with a valve, and GABr is introduced into the left channel opening to make the MAPbI3 in the remaining hood react chemically. The reaction time is 2 minutes to make the large cation GA + Replacement of MA + To form a more stable and uniform perovskite light-absorbing layer, open the valve on the right and introduce nitrogen gas on the left to blow away the excess GABr vapor.

[0056] S5, transferring the transparent conductive layer having the perovskite light absorbing layer to a vacuum evaporator to form an electron transport layer, wherein the deposition process may be: -4 C deposited at a thickness of 20 nm at a low pressure below Pa 60 , then we will have C 60 The transparent conductive layer is transferred to the ALD machine to deposit 20nm of tin oxide (SnO2).

[0057] S6, at 5×10 -4 Pa or less Silver with a thickness of 100 nm was deposited at a rate of to form a metal electrode layer.

[0058] According to another aspect of the embodiment of the present application, a perovskite solar cell is provided, such as Figure 1 As shown, it includes: a hole transport layer 20 located on one side of a transparent conductive layer (not shown in the figure); a self-assembled molecular layer 30, located on the side of the hole transport layer 20 away from the transparent conductive layer; a perovskite light absorption layer 40, located on the side of the self-assembled molecular layer 30 away from the hole transport layer 20, the perovskite light absorption layer 40 has cations located at the A position, the cations include a first cation and a second cation, and the ionic radii of the first cation and the second cation are different; an electron transport layer 50, located on the side of the perovskite light absorption layer 40 away from the self-assembled molecular layer 30.

[0059] The perovskite solar cell in the above-mentioned embodiment can be prepared by the above-mentioned method for preparing a perovskite solar cell, so that the perovskite solar cell has a more dense and uniform perovskite light-absorbing layer with a more stable skeleton compared to the prior art, and the adhesion between the perovskite light-absorbing layer 40 and the hole transport layer 20 is stronger and the interface defects are fewer, thereby improving the performance of the perovskite solar cell and solving the problem of low photoelectric conversion efficiency and poor stability of the perovskite solar cell caused by thin film defects of the perovskite light-absorbing layer 40 in the prior art.

[0060] In some optional embodiments, the self-assembled molecular layer 30 has a plurality of different functional groups, including methoxy groups, phosphonic acid groups and carboxyl groups.

[0061] In the above embodiment, different functional groups may come from different components in the self-assembled molecular layer 30 , and the different components may include self-assembled molecules and isoalkylammonium hydrochloride.

[0062] Exemplarily, the methoxy or carboxyl groups in the self-assembled molecular layer 30 are from self-assembled molecules. The self-assembled molecules may include, but are not limited to, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid layer (MeO-2PACz), [4-(3,6-dimethyloxy-9H-carbazole-9-yl)butyl]phosphonic acid layer (Me-4PACz) and methoxy-4-phenyl-1,2-propanedione (MeO-4PADBC).

[0063] For example, the phosphonic acid groups in the self-assembled molecular layer 30 are from isoalkylammonium hydrochloride, which may be 6-(iodo-5λ-azaalkyl)acetic acid.

[0064] In some optional embodiments, such as Figure 1 As shown, the perovskite solar cell may further include: a first electrode layer 10 located on a side of the hole transport layer 20 away from the self-assembled molecular layer 30 ; and a second electrode layer 60 located on a side of the electron transport layer 50 away from the perovskite light absorbing layer 40 .

[0065] Specifically, the first electrode layer 10 may be a transparent conductive layer, and the material of the transparent conductive layer may include but is not limited to indium tin oxide (ITO), fluorinated tin oxide (FTO), indium zinc oxide (IZO) and aluminum zinc oxide (AZO).

[0066] Specifically, the second electrode layer 60 may be a metal electrode layer, and the material of the metal electrode layer may include, but is not limited to, gold (Au), silver (Ag), copper (Cu), and aluminum (Al).

[0067] According to another aspect of the present invention, a stacked cell is provided, comprising a crystalline silicon cell and any one of the above-mentioned perovskite solar cells. Specifically, the above-mentioned crystalline silicon cell and the above-mentioned perovskite solar cell are stacked.

[0068] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0069] Through the embodiments of the present application, a hole transport layer is first formed on one side of the provided transparent conductive layer, and then a self-assembled molecular layer is formed on the side of the hole transport layer away from the transparent conductive layer, and then a perovskite light absorption layer is formed on the side of the self-assembled molecular layer away from the hole transport layer. The self-assembled molecular layer can not only adjust the energy level at the interface between the hole transport layer and the perovskite light absorption layer to improve the energy level matching between the hole transport layer and the perovskite light absorption layer; it can also enhance the adhesion between the hole transport layer and the perovskite light absorption layer to reduce defects and instability at the interface, thereby achieving the effect of promoting the effective transmission of holes and reducing energy loss. Further, in the step of forming the above-mentioned perovskite light-absorbing layer, the embodiment of the present application first forms a perovskite film ABX3, A is a first cation, and then after the perovskite film is wrapped with a steam hood, a gaseous compound containing halogen ions and a second cation is passed into the steam hood through the first channel of the steam hood, so that part of the perovskite crystals in the perovskite film undergo a substitution reaction with the gaseous compound (that is, the first cation at the A position in part of the perovskite film ABX3 is replaced with a second cation), and finally a perovskite light-absorbing layer is formed. Wherein, since the ionic radius of the above-mentioned second cation is greater than the ionic radius of the first cation, the film quality after the substitution reaction is more dense and uniform than the film quality of the perovskite film, thereby obtaining a perovskite light-absorbing layer with a more stable skeleton. And then after the electron transport layer is formed on the side of the perovskite light-absorbing layer away from the self-assembled molecular layer, a perovskite solar cell with better performance can be obtained, thereby solving the problem of low photoelectric conversion efficiency and poor stability of the perovskite solar cell caused by the film defects of the perovskite light-absorbing layer in the prior art.

[0070] 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. A method for preparing a perovskite solar cell, It is characterized in that include: Providing a transparent conductive layer, wherein one side of the transparent conductive layer forms a hole transport layer; forming a self-assembled molecular layer on a side of the hole transport layer away from the transparent conductive layer; A perovskite film is formed on a side of the self-assembled molecular layer away from the hole transport layer, and the perovskite film is wrapped with a steam cover, wherein the steam cover has a first channel connected to the outside, and the perovskite film has a first cation located at the A position; Passing a vapor compound containing halogen ions and a second cation into the steam hood through the first channel, so that a portion of the perovskite crystals in the perovskite film undergoes a substitution reaction with the vapor compound to form a perovskite light-absorbing layer, wherein the substitution reaction is used to replace the first cation in the portion of the perovskite crystals with the second cation, and the ion radius of the second cation is greater than the ion radius of the first cation; The steam cover is removed, and an electron transport layer is formed on a side of the perovskite light absorbing layer away from the self-assembled molecular layer.

2. The preparation method according to claim 1, It is characterized in that The steam hood has a second passage communicating with the outside, and the method further comprises: After the step of forming the perovskite light absorbing layer and before the step of removing the steam hood, an inert gas is introduced into the steam hood through the first channel, so that the inert gas removes the gaseous compounds that do not participate in the replacement reaction from the steam hood through the second channel.

3. The preparation method according to claim 1, It is characterized in that The steps of forming the self-assembled molecular layer include: Mixing isoalkylammonium hydrochloride and the self-assembled molecules in the self-assembled molecular layer according to a preset ratio to obtain a mixed solution; coating the mixed solution on a side of the hole transport layer away from the transparent conductive layer to form a wet film containing the isoalkylammonium hydrochloride and the self-assembling molecules; The wet film is subjected to heat treatment to form the self-assembled molecular layer.

4. The preparation method according to claim 3, It is characterized in that The isoalkylammonium hydrochloride is 6-(iodo-5-azaalkyl)acetic acid.

5. The preparation method according to any one of claims 1 to 4, It is characterized in that The self-assembled molecules in the self-assembled molecular layer include one of the following: a (2-(9H-carbazole-9-yl)ethyl)phosphonic acid layer, a [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid layer, a [4-(3,6-dimethyloxy-9H-carbazole-9-yl)butyl]phosphonic acid layer and methoxy-4-phenyl-1,2-propanedione.

6. The preparation method according to any one of claims 1 to 4, It is characterized in that The steps of forming the perovskite film include: forming a perovskite precursor film on a side of the self-assembled molecular layer away from the hole transport layer; The perovskite precursor film is heat-treated to form the perovskite film, wherein the temperature of the heat treatment is less than or equal to 100° C.

7. The preparation method according to any one of claims 1 to 4, It is characterized in that The first cation is a methylamine ion, and the second cation is a guanidine ion.

8. The preparation method according to any one of claims 1 to 4, It is characterized in that The hole transport layer is a nickel oxide layer.

9. A perovskite solar cell, It is characterized in that include: a hole transport layer located on one side of the transparent conductive layer; A self-assembled molecular layer is located on a side of the hole transport layer away from the transparent conductive layer; A perovskite light-absorbing layer is located on a side of the self-assembled molecular layer away from the hole transport layer, the perovskite light-absorbing layer has a cation located at position A, the cation includes a first cation and a second cation, and the first cation and the second cation have different ionic radii; The electron transport layer is located on a side of the perovskite light absorbing layer away from the self-assembled molecular layer.

10. The perovskite solar cell according to claim 9, It is characterized in that The self-assembled molecular layer has a plurality of different functional groups, including methoxy groups, phosphonic acid groups and carboxyl groups.

11. The perovskite solar cell according to claim 9 or 10, It is characterized in that The perovskite solar cell further comprises: A first electrode layer, located on a side of the hole transport layer away from the self-assembled molecular layer; The second electrode layer is located on a side of the electron transport layer away from the perovskite light absorbing layer.

12. A laminated battery, It is characterized in that The invention comprises a crystalline silicon cell and the perovskite solar cell according to any one of claims 9 to 11.

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