Perovskite cell and preparation method thereof, laminated cell and photovoltaic module

Abstract

The invention provides a perovskite cell and a preparation method thereof, a laminated cell and a photovoltaic module. The perovskite cell comprises a first transparent conductive layer, a first charge transport layer, a perovskite active layer, a second charge transport layer, a second transparent conductive layer and a first interface modification layer, one of the first charge transport layer and the second charge transport layer is a hole transport layer, and the other one is an electron transport layer; the first interface modification layer is arranged between the hole transport layer and the perovskite active layer and comprises graphene oxide and carbon nanotubes. Therefore, an oxygen-containing functional group of GO can form a coordinate bond or a hydrogen bond with a defect site of the hole transport layer or the perovskite active layer, and non-radiative recombination is inhibited, so that the open-circuit voltage of the perovskite cell is improved; gO can improve the interface wettability problem and improve the subsequent film forming quality; the CNT can construct a high mobility channel, and the GO fills the CNT network gap, thereby being more beneficial to carrier transport, and further improving the fill factor of the perovskite cell.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to perovskite batteries and their preparation methods, tandem batteries, and photovoltaic modules. Background Technology

[0002] Perovskite / crystalline silicon tandem solar cells are structures that combine crystalline silicon solar cells and perovskite solar cells, achieving improved conversion efficiency through complementary advantages and synergistic effects. In tandem cells, recombination losses at the interface are the main cause of voltage loss in both the perovskite top cell and the tandem cell, severely limiting device performance improvement. For example, the hole transport layer NiOx is typically deposited using magnetron sputtering, resulting in a high surface defect density and increased recombination probability. Although a small-molecule self-assembled layer, such as 4PACz, can be spin-coated onto the NiOx surface to improve the defect situation, 4PACz has poor wettability, easily causing uneven deposition on the surface of the subsequently prepared perovskite thin film. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, one object of this invention is to provide a perovskite solar cell in which interface defects in the hole transport layer are effectively improved, thereby effectively suppressing nonradiative recombination.

[0004] In one aspect, the present invention provides a perovskite solar cell. According to an embodiment of the present invention, the perovskite solar cell includes: a first transparent conductive layer, a first charge transport layer, a perovskite active layer, a second charge transport layer, and a second transparent conductive layer, wherein one of the first charge transport layer and the second charge transport layer is a hole transport layer, and the other is an electron transport layer; the perovskite solar cell further includes: a first interface modification layer, the first interface modification layer being disposed between the hole transport layer and the perovskite active layer, and the first interface modification layer comprising graphene oxide (GO) and carbon nanotubes (CNTs). Thus, oxygen-containing functional groups (such as carboxyl groups and epoxy groups) on the surface of graphene oxide can interact with the hole transport layer (such as NiO). x Spiro-OMeTAD) or defect sites in the perovskite active layer (such as uncoordinated Pb) 2+ GO forms coordination bonds or hydrogen bonds (such as dangling bonds) to suppress nonradiative recombination, thereby increasing the open-circuit voltage (Voc) of perovskite solar cells. The oxygen-containing functional groups (such as carboxyl groups) of GO are hydrophilic, which can improve the interface wettability problem and improve the quality of subsequent film formation. CNTs can construct high-mobility channels. GO fills the gaps in the CNT network. The resistance of this first interface modification layer is lower than that of monolayer GO, which is more conducive to carrier transport and thus improves the fill factor (FF) of perovskite solar cells.

[0005] According to an embodiment of the present application, the first interface modification layer further comprises reduced graphene oxide.

[0006] According to an embodiment of the present application, the first interface modification layer has a thickness of 5-10 nm.

[0007] According to an embodiment of the present application, the perovskite cell further comprises a second interface modification layer, the second interface modification layer is arranged between the first interface modification layer and the hole transport layer, and the second interface modification layer comprises graphene oxide or comprises graphene oxide and reduced graphene oxide.

[0008] According to an embodiment of the present application, the second interface modification layer has a thickness of 1-4 nm.

[0009] In another aspect of the present application, the present application provides a method for preparing the perovskite cell described above. According to an embodiment of the present application, the method for preparing the perovskite cell comprises the steps of preparing a first transparent conductive layer, a first charge transport layer, a perovskite active layer, a second charge transport layer and a second transparent conductive layer, one of the first charge transport layer and the second charge transport layer is a hole transport layer, and the other is an electron transport layer, and the method for preparing the perovskite cell further comprises: forming a first interface modification layer between the hole transport layer and the perovskite active layer, and the method for forming the first interface modification layer comprises: coating a first interface modification liquid and heat treating to obtain the first interface modification layer. Thus, the formation of the above-mentioned first interface modification layer, the oxygen-containing functional groups (such as carboxyl groups and epoxy groups) on the surface of graphene oxide can form coordination bonds or hydrogen bonds with the defect sites (such as uncoordinated Pb x , and dangling bonds) of the hole transport layer (such as NiO 2+ , Spiro-OMeTAD) or the perovskite active layer, inhibit non-radiative recombination, and thus improve the open-circuit voltage (Voc) of the perovskite cell; the oxygen-containing functional groups (such as carboxyl groups) of GO have hydrophilicity, which can improve the interface wetting problem and improve the subsequent film formation quality; CNT can construct a high-mobility channel, and GO can fill the gap between the CNT network, and the resistance of the first interface modification layer is lower than that of single-layer GO, which is more conducive to the carrier transport, and thus improves the fill factor (FF) of the perovskite cell.

[0010] According to an embodiment of the present application, in the first interface modification liquid, the concentration of graphene oxide is 0.05-0.25 mg / mL, the concentration of carbon nanotubes is 0.05-0.15 mg / mL, and / or the temperature of the heat treatment is 100-150°C, and the time is 10-30 minutes.

[0011] According to an embodiment of the present application, the method for preparing the perovskite cell further comprises: forming a second interface modification layer between the first interface modification layer and the hole transport layer, and the method for forming the second interface modification layer comprises: coating a second interface modification solution, and annealing to obtain the second interface modification layer.

[0012] According to an embodiment of the present application, the concentration of graphene oxide in the second interface modification solution is 0.1-0.5 mg / mL.

[0013] In another aspect of the present application, the present application provides a tandem cell. According to an embodiment of the present application, the tandem cell comprises a crystalline silicon bottom cell and a perovskite top cell located on the light-receiving surface of the crystalline silicon bottom cell, and the perovskite top cell is the perovskite cell described above. Thus, the open-circuit voltage (Voc) and the fill factor (FF) of the tandem cell are both significantly improved, thereby improving the cell efficiency of the tandem cell.

[0014] In another aspect of the present application, the present application provides a photovoltaic module according to an embodiment of the present application. The photovoltaic module comprises the perovskite cell described above, or comprises the tandem cell described above. Thus, the photovoltaic module has a high photoelectric conversion efficiency.

[0015] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings. Figure 1 is a structural schematic diagram of a perovskite cell in one embodiment of the present application; Figure 2 is a structural schematic diagram of a perovskite cell in another embodiment of the present application. DETAILED DESCRIPTION

[0017] The scheme of the present application will be explained below in connection with embodiments. Those skilled in the art will understand that the following embodiments are only for illustrating the present application, and should not be regarded as limiting the scope of the present application. If a specific technique or condition is not specified in the embodiments, the technique or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0018] The present application will be described below in connection with specific embodiments, and it should be noted that these embodiments are only descriptive, and do not limit the present application in any way.

[0019] In one aspect of the present application, the present application provides a perovskite cell. According to an embodiment of the present application, the perovskite cell comprises: a first transparent conductive layer 11, a first charge transport layer 21, a perovskite active layer 30, a second charge transport layer 22, and a second transparent conductive layer 12, one of the first charge transport layer 21 and the second charge transport layer 22 is a hole transport layer, and the other is an electron transport layer Figure 1 , taking the first charge transport layer 21 as the hole transport layer as an example); the perovskite cell further comprises: a first interface modification layer 41, the first interface modification layer 41 is arranged between the hole transport layer and the perovskite active layer 30. In some embodiments, referring to Figure 1 , the first charge transport layer 21 is arranged on one side of the first transparent conductive layer 11; the perovskite active layer 30 is arranged on a side of the first charge transport layer 21 away from the first transparent conductive layer 11; the second charge transport layer 22 is arranged on a side of the perovskite active layer 30 away from the first transparent conductive layer 11, one of the first charge transport layer 21 and the second charge transport layer 22 is a hole transport layer, and the other is an electron transport layer; the second transparent conductive layer 12 is arranged on a side of the second charge transport layer 22 away from the first transparent conductive layer 11, and the first interface modification layer 41 is arranged between the hole transport layer and the perovskite active layer 30.

[0020] According to an embodiment of the present application, the first interface modification layer 41 comprises graphene oxide (GO) and carbon nanotubes (CNT). The oxygen-containing functional groups (such as carboxyl, epoxy) on the surface of the graphene oxide (GO) can form coordination bonds or hydrogen bonds with the hole transport layer (such as NiO x , Spiro-OMeTAD) or the defect sites (such as uncoordinated Pb 2+ , dangling bonds) of the perovskite active layer, inhibit non-radiative recombination, and thus improve the open-circuit voltage (Voc) of the perovskite cell; the oxygen-containing functional groups (such as carboxyl) of the GO have hydrophilicity, which can improve the interface wetting problem and improve the subsequent film formation quality; the CNT can construct a high-mobility channel, and the GO fills the gap between the CNT network, the resistance of the first interface modification layer is lower than that of a single-layer GO, which is more conducive to carrier transport, and thus improves the fill factor (FF) of the perovskite cell.

[0021] The graphene oxide (GO) has good hydrophilicity, which is conducive to perovskite nucleation and growth, and is rich in oxygen-containing functional groups (-COOH, -OH), which can effectively passivate the defects on the surface of NiOx. However, the conductivity of GO is poor, which will increase the series resistance, and the excessive hydrophilicity may affect the long-term stability of the device. The conductivity of CNT is excellent, which is conducive to hole extraction and transmission, and the one-dimensional structure of CNT can provide a charge transport channel. However, CNT is prone to aggregation, has poor dispersibility in solvents, and has weak defect passivation ability for the hole transport layer (such as NiOx). Moreover, CNT is hydrophobic, which will exacerbate the perovskite film formation problem. In the present application, the interface modification layer contains both graphene oxide and carbon nanotubes. GO and CNT not only make up for each other's shortcomings, but also better improve the performance of the battery, as follows: First, GO as a defect repair agent, its oxygen-containing functional groups can grab the uncoordinated ions (such as Pb 2+ , I⁻) on the surface of the hole transport layer (such as NiOx) and the bottom of the perovskite through coordination bonds and hydrogen bonds, greatly reducing the interface defect state density and inhibiting non-radiative recombination. The holes separated by the GO passivated interface can be quickly captured by CNT and efficiently transported to the hole transport layer. That is, GO solves the problem of weak passivation ability of CNT, and CNT solves the problem of poor conductivity of GO. Therefore, the setting of the first interface modification layer in the present application can significantly improve the open-circuit voltage (Voc) and fill factor (FF) of the perovskite solar cell at the same time (the Voc improvement is due to the reduction of recombination, and the FF improvement is due to the reduction of series resistance and the improvement of charge collection efficiency).

[0022] Second, GO has a two-dimensional sheet structure, which can provide surface passivation and certain energy level regulation, but is prone to stacking and forming insulating regions that hinder charge transport. CNT has a one-dimensional tubular structure with strong conductivity, but poor dispersibility, easy to agglomerate, and difficult to form a complete and uniform film. The first interface modification layer in the present application combines GO and CNT. CNT can act as a supporting skeleton to prevent GO sheets from excessive stacking and maintain the dispersibility of GO layers. Meanwhile, the oxygen functional groups of GO can improve the dispersibility and wettability of CNT, so that the composite film can maintain continuous coverage and provide conductive channels. In this way, the first interface modification layer avoids the problem of insulating GO and solves the problems of poor dispersibility and uneven film formation of CNT, forming a stable, uniform and conductive interface layer.

[0023] Third, the GO surface contains oxygen functional groups, which can adjust the work function to better match the energy levels of the hole transport layer (such as NiOx) and the perovskite layer. CNTs have high conductivity and a relatively stable work function. Therefore, when the two are combined, the energy level modulation effect of GO and the conductivity of CNTs combine to make the overall work function of the first interface modification layer closer to the perovskite valence band, while reducing the interface barrier. In this way, the first interface modification layer can not only improve energy level matching, but also reduce the energy loss of charge injection and increase the open-circuit voltage (Voc).

[0024] In summary, the composite of GO and CNT in the first interface modification layer of this invention is not merely a superposition of their effects, but rather produces a synergistic effect: CNT suppresses the stacking of the GO layer and provides a fast charge transport channel, while GO improves the dispersion of CNT and passivates NiOx surface defects. Together, they give the interface layer excellent film uniformity, defect passivation capability, energy level matching, and carrier transport efficiency. This synergistic effect significantly improves the crystal quality of the perovskite thin film and the photoelectric conversion efficiency and stability of the device while reducing interfacial recombination losses—effects that cannot be achieved by using GO or CNT alone.

[0025] According to some embodiments of the present invention, the first interface modification layer further includes reduced graphene oxide. Thus, some graphene oxide (GO) is partially reduced to reduced graphene oxide, improving the conductivity of graphene and simultaneously enhancing the π-π interaction between GO and CNTs, thereby further improving the interfacial contact.

[0026] According to some embodiments of the present invention, the thickness of the first interface modification layer is 5~10 nm, such as 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc. Therefore, the first interface modification layer has good adhesion, enhances interfacial contact, and the aforementioned thickness is convenient for fabrication and provides better thickness uniformity. If the thickness is too large, the overall resistivity of the first interface modification layer may be too high, resulting in greater optical loss.

[0027] According to some embodiments of the present invention, with reference to Figure 2 The perovskite solar cell further includes a second interface modification layer 42, which is disposed between the first interface modification layer 41 and the hole transport layer (taking the first charge transport layer 21 as an example). The second interface modification layer 42 includes graphene oxide, or graphene oxide and reduced graphene oxide. Therefore, the second interface modification layer can further enhance the passivation effect on the hole transport layer and better improve interface defects.

[0028] According to some embodiments of the present application, the second interface modification layer has a thickness of 1-4 nm, such as 1 nm, 2 nm, 3 nm or 4 nm, etc. Thus, the second interface modification layer with the above thickness can better ensure that the charges can tunnel and passivate the hole transport layer. If the second interface modification layer is too thick, it can hinder the charge transport and increase the series resistance.

[0029] According to some embodiments of the present application, the material of the first and second transparent conductive layers includes, but is not limited to, ITO, IZO and other transparent conductive materials. The thickness of the first transparent conductive layer can be 5-10 nm, and the thickness of the second transparent conductive layer can be 30-100 nm.

[0030] According to some embodiments of the present application, the material structure of the perovskite active layer can be ABX3, wherein A is a monovalent cation, including but not limited to one or more monovalent cation mixtures of cesium (Cs), rubidium (Rb), methylamine (CH3NH3), formamidinium (CH2(NH2)2); B is a divalent cation, including but not limited to one or more divalent cation mixtures of lead (Pb), tin (Sn), X is a monovalent anion, including but not limited to one or more monovalent anion mixtures of iodine (I), bromine (Br), chlorine (Cl), fluorine (F), thiocyanate ion (SCN).

[0031] According to some embodiments of the present application, the material of the hole transport layer includes nickel oxide (NiO xCuSCN, 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'-bifluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz), [4-(9H-carbazol-9-yl)butyl]phosphonic acid (4PACz), (4-(3,6-dibromo-9H-carbazol-9-yl)butyl)phosphonic acid (Br-4PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazol-9-yl)ethyl)phosphonic acid (Br-2PACz), and the like. In some embodiments, the material of the hole transport layer is nickel oxide, and thus the improvement on the performance of the battery is better. The thickness can be 5-30 nm.

[0032] According to some embodiments of the present application, the electron transport material of the electron transport layer includes, but is not limited to, tin oxide, fullerene and its derivatives, imide compounds, quinone compounds, and the like. Exemplarily, the imide compounds include at least one of phthalimide, succinimide, N-bromosuccinimide, glutarimide or maleimide; exemplarily, the quinone compounds include at least one of benzoquinone, naphthoquinone, phenanthraquinone or anthraquinone; exemplarily, the fullerene and its derivatives include at least one of fullerene C 60 , fullerene C 70 , PCBM ([6,6]-phenyl-C 61 butyric acid methyl ester), [6,6]-phenyl-C 71 butyric acid methyl ester (PC 71 BM). Further, the electron transport layer can be a single-layer structure, or a double-layer or triple-layer structure. In some embodiments, the electron transport layer can include a C60 layer with a thickness of 5-20 nm and a tin oxide layer with a thickness of 15-20 nm, and the tin oxide layer can be arranged to protect the C60 in subsequent processes. In some embodiments, the thickness of the C60 layer can be 5-20 nm, and the thickness of the tin oxide layer can be 10-30 nm.

[0033] In another aspect of the present application, the present application provides a method for preparing the perovskite cell described above. According to an embodiment of the present application, the method for preparing the perovskite cell comprises the steps of preparing a first transparent conductive layer, a first charge transport layer, a perovskite active layer, a second charge transport layer and a second transparent conductive layer, one of the first charge transport layer and the second charge transport layer being a hole transport layer and the other being an electron transport layer, and the method for preparing the perovskite cell further comprises: forming a first interface modification layer between the hole transport layer and the perovskite active layer, and the method for forming the first interface modification layer comprises: coating a first interface modification solution and heat treating to obtain the first interface modification layer.

[0034] According to some embodiments of the present application, the concentration of graphene oxide in the first interface modification solution is 0.05-0.25 mg / mL, such as 0.05 mg / mL, 0.08 mg / mL, 0.1 mg / mL, 0.12 mg / mL, 0.15 mg / mL, 0.18 mg / mL, 0.2 mg / mL, 0.23 mg / mL, 0.25 mg / mL, etc., and the concentration of carbon nanotubes in the first interface modification solution is 0.05-0.15 mg / mL, such as 0.05 mg / mL, 0.06 mg / mL, 0.07 mg / mL, 0.08 mg / mL, 0.09 mg / mL, 0.1 mg / mL, 0.11 mg / mL, 0.12 mg / mL, 0.13 mg / mL, 0.14 mg / mL, 0.15 mg / mL, etc. In this way, the graphene oxide and the carbon nanotubes can be uniformly dispersed without aggregation, which is conducive to preparing a first interface modification layer with uniform thickness and uniform dispersion. If the concentration of graphene oxide or carbon nanotubes is too high, it is relatively difficult to prepare a fine interface modification film. If the concentration of graphene oxide or carbon nanotubes is too low, it is easy to cause the modification layer to be discontinuous.

[0035] According to some embodiments of the present application, the heat treatment is performed at a temperature of 100-150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., for a time of 10-30 minutes, such as 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc. In this way, the residual solvent can be effectively evaporated and removed, the adhesion can be improved, and at the same time, the GO is prevented from being excessively reduced or the perovskite active layer or the hole transport layer is prevented from being damaged for a long time at a high temperature.

[0036] According to an embodiment of the present application, the method for preparing the perovskite cell further comprises: forming a second interface modification layer between the first interface modification layer and the hole transport layer, and the method for forming the second interface modification layer comprises: coating a second interface modification solution and annealing to obtain the second interface modification layer.

[0037] According to some embodiments of the present application, the concentration of graphene oxide in the second interface modification solution is 0.1-0.5 mg / mL, such as 0.1 mg / mL, 0.15 mg / mL, 0.2 mg / mL, 0.25 mg / mL, 0.30 mg / mL, 0.35 mg / mL, 0.4 mg / mL, 0.45 mg / mL, 0.50 mg / mL, etc. In this way, the graphene oxide can be uniformly dispersed without aggregation, which is conducive to the preparation of a second interface modification layer with uniform thickness and uniform dispersion. In some embodiments, the annealing temperature can be 100-150°C, and the time can be 10-30 minutes.

[0038] According to some embodiments of the present application, the method for preparing a perovskite cell comprises: S1: preparing a hole transport layer on one side surface of the first transparent conductive layer by a magnetron sputtering or coating method (such as depositing nickel oxide as a hole transport layer by magnetron sputtering).

[0039] S2: ultrasonically dispersing graphene oxide in a solvent (such as water and / or ethanol) to obtain a GO dispersion liquid with a concentration of 0.1-0.5 mg / mL; ultrasonically dispersing semiconductive single-walled CNT in a solvent with the aid of a dispersant (such as SDBS) to obtain a CNT dispersion liquid with a concentration of 0.1-0.3 mg / mL; mixing and ultrasonically treating the GO dispersion liquid and the CNT dispersion liquid according to a specific volume ratio (such as 1:1) to obtain a first interface modification solution.

[0040] S3: spin-coating the ultra-thin GO dispersion liquid on the surface of the hole transport layer at a speed of 2000 rpm for 15-30 s, and annealing to obtain a second interface modification layer. S4: spin-coating the first interface modification solution on the surface of the second interface modification layer at a speed of 3000 rpm for 25-60 s, and heat-treating the thin film after spin-coating in an inert atmosphere or air at a temperature of 100-150°C for a time of 10-30 minutes to obtain a first interface modification layer.

[0041] S5: spin-coating a perovskite precursor solution on the surface of the first interface modification layer, first at a speed of 2500 rpm for 10 s, and then at a speed of 3500 rpm for 25 s; 5 s before the end of the spin-coating process, 200 μL of chlorobenzene is dropped into the center of the substrate, and after the spin-coating is stopped, the substrate is immediately transferred to a heating plate at 100°C and annealed for 15-20 min to obtain a perovskite active layer with a thickness of 500-900 nm.

[0042] S6: preparing a C60 layer with a thickness of 5-20 nm on the surface of the perovskite active layer by a thermal evaporation method, and then preparing a SnO2 layer with a thickness of 10-30 nm by an atomic layer deposition method to obtain an electron transport layer.

[0043] S7: A second transparent conductive layer is deposited on one side of the electron transport layer using a sputtering method.

[0044] S8: An Ag electrode with a thickness of 50-120 nm is deposited on the surface of the transparent conductive layer using a second thermal evaporation method.

[0045] S9: Deposit an antireflection layer with a thickness of 50-100 nm on the side of the outermost surface of the battery away from the second transparent conductive layer using a thermal evaporation method (the material can be MgF2).

[0046] According to an embodiment of the present invention, in the formation of the first interface modification layer, the oxygen-containing functional groups (such as carboxyl groups, epoxy groups) on the surface of graphene oxide can interact with the hole transport layer (such as NiO). x Spiro-OMeTAD) or defect sites in the perovskite active layer (such as uncoordinated Pb) 2+ GO forms coordination bonds or hydrogen bonds (such as dangling bonds) to suppress nonradiative recombination, thereby increasing the open-circuit voltage (Voc) of perovskite solar cells. The oxygen-containing functional groups (such as carboxyl groups) of GO are hydrophilic, which can improve the interface wettability problem and improve the quality of subsequent film formation. CNTs can construct high-mobility channels. GO fills the gaps in the CNT network. The resistance of this first interface modification layer is lower than that of monolayer GO, which is more conducive to carrier transport and thus improves the fill factor (FF) of perovskite solar cells.

[0047] In another aspect, the present invention provides a tandem solar cell. According to an embodiment of the present invention, the tandem solar cell includes: a crystalline silicon bottom cell and a perovskite top cell located on the light-receiving surface of the crystalline silicon bottom cell, wherein the perovskite top cell is the perovskite cell described above. Thus, the open-circuit voltage (Voc) and fill factor (FF) of the tandem solar cell are significantly improved simultaneously, thereby improving the cell efficiency of the tandem solar cell.

[0048] According to embodiments of the present invention, there are no specific limitations on the type of crystalline silicon base cell, and those skilled in the art can flexibly select one according to actual needs. In some embodiments, the crystalline silicon base cell can be a TOPCon cell, a BC cell (such as a TBC cell, an HBC cell, or a hybrid BC cell), etc.

[0049] According to an embodiment of the present invention, the first transparent conductive layer may be a composite layer serving as a base cell of crystalline silicon and a top cell of perovskite.

[0050] In another aspect, the present invention provides a photovoltaic module according to an embodiment of the invention. The photovoltaic module includes the perovskite cell described above, or includes the tandem cell described above. Therefore, the photovoltaic module has a high photoelectric conversion efficiency.

[0051] Example Example 1 Step 1, polishing the silicon wafer with sodium hydroxide lye.

[0052] Step 2, depositing a first tunnel layer with a thickness of 2.1 nm and a first polysilicon layer with a thickness of 300 nm on the back of the silicon wafer in sequence by using LPCVD deposition method, wherein the deposition conditions of the first tunnel layer are: oxygen flow rate of 30000 sccm, temperature of 600℃, process time of 1000s, and tube soaking of 500s; the deposition conditions of the first polysilicon layer are: deposition temperature of 550℃, process time of 11100s, and silane flow rates of 190sccm, 440sccm, and 620sccm in three-stage gas feeding mode.

[0053] Step 3, boron diffusion on the first polysilicon layer by using boron source trichloride, boron source flow rate of 250sccm, temperature of 855℃, process time of 1000s, pushing temperature of 950℃, process time of 1100s, oxidation temperature of 950℃, oxygen flow rate of 8000sccm, and oxidation time of 1600s, to finally form a boron-doped polysilicon layer + borosilicate glass (BSG) structure, and a PN junction is formed between the boron-doped polysilicon layer and the n-type substrate silicon wafer, wherein the surface concentration of the boron-doped polysilicon layer is 6.4×10^19cm -3 , the BSG thickness is 50nm, and the sheet resistance of the boron-doped polysilicon layer is 80.

[0054] Step 4, removing the BSG formed by the boron diffusion on the front and side surfaces by using a wet chain-type machine (HF solution).

[0055] Step 5, removing the boron-doped polysilicon layer on the front and side surfaces by using an alkali washing wet tank.

[0056] Step 6, depositing a second tunnel layer with a thickness of 2.1 nm and a second polysilicon layer with a thickness of 235 nm on the back of the silicon wafer in sequence by using LPCVD deposition method, wherein the deposition conditions of the second tunnel layer are: oxygen flow rate of 30000 sccm, temperature of 600℃, process time of 1000s, and tube soaking of 500s; the deposition conditions of the second polysilicon layer are: deposition temperature of 600℃, process time of 3000s, and silane flow rates of 190sccm, 440sccm, and 620sccm in three-stage gas feeding mode.

[0057] Step 7, phosphorus diffusion to the second polysilicon layer: phosphorus source is phosphorus pentachloride, the flow rate of the phosphorus source is 1200sccm, the temperature is 810℃, the process time is 1200s; the push temperature is 880℃, the process time is 1100s; the oxidation temperature is 870℃, the oxygen flow rate is 2100sccm, and the oxidation time is 820s, so as to finally form a phosphorus-doped polysilicon layer + phosphosilicate glass (PSG) structure, wherein the surface concentration of the boron-doped polysilicon layer is 5.7×10^20cm -3 , the thickness of the PSG is 50nm, and the sheet resistance of the phosphorus-doped polysilicon layer is 20.

[0058] Step 8, removing the back surface and the side surface to form a PSG around the diffusion by a wet chain machine (HF solution).

[0059] Step 9, removing the phosphorus-doped polysilicon layer around the deposition and the back BSG and the front PSG deposited on the back side surface by a wet alkali tank and an acid tank, respectively.

[0060] Step 10, depositing an aluminum oxide passivation layer by a back-to-back double-insertion method by an ALD deposition method, the ALD process temperature is 300℃, the process time is 900s, and the thickness of the passivation layer is 4.3nm.

[0061] Step 11, depositing to form an anti-reflection film, the film deposition process temperature is 530℃, and the film is divided into three layers, in the direction away from the silicon wafer, the deposition sequence is silicon nitride 1, silicon nitride 2, and silicon nitride 3 in turn, the thickness of the three layers of film is between 28nm, 29nm, and 30nm respectively, the final overall film layer thickness is 87nm, and the refractive index is 2.12.

[0062] Step 12, forming a silver metal grid line on the back surface by a screen printing method, that is, a back electrode, forming an ohmic contact between the sintered metal and the boron-doped polysilicon layer, collecting and leading out the current, the sintering peak temperature is 710℃, so as to obtain a TBC bottom cell.

[0063] Step 13, depositing an ITO conductive layer, that is, a first transparent conductive layer, on the upper surface of the crystalline silicon bottom cell (that is, on the surface of the n-type doped polysilicon layer) by a magnetron sputtering method, the thickness is 7nm.

[0064] Step 14, preparing a hole transport layer on the side surface of the first transparent conductive layer away from the crystalline silicon bottom cell by a magnetron sputtering method, the material of the hole transport layer is NiOx, and the thickness of the hole transport layer is 20nm.

[0065] Step 15, ultrasonic dispersion of graphene oxide in a mixed solvent of water and ethanol to obtain a GO dispersion with a concentration of 0.25 mg / mL; ultrasonic dispersion of semiconducting single-walled CNT in a solvent with the aid of a dispersant (SDBS) to obtain a CNT dispersion with a concentration of 0.2 mg / mL; mixing and ultrasonic treatment of the GO dispersion and the CNT dispersion in a volume ratio of 1:1 to obtain a first interfacial modification solution.

[0066] Step 16, spin coating of an ultrathin GO dispersion on the surface of the NiOx layer at a speed of 2000 rpm for 23 s, and annealing at 120°C to obtain a second interfacial modification layer with a thickness of 4 nm.

[0067] Step 17, spin coating of the first interfacial modification solution on the surface of the second interfacial modification layer at a speed of 3000 rpm for 45 s, and heat treatment of the thin film in an inert atmosphere at a temperature of 120°C for 15 minutes to obtain a first interfacial modification layer with a thickness of 7 nm.

[0068] Step 18, dispersion of PbI2, PbBr2, CsI, FAI, and MABr in a mixed solvent of DMF and DMSO (volume ratio of DMF to DMSO is 5:1) to obtain a perovskite precursor solution, and preparation of a perovskite active layer on the side surface of the first interfacial modification layer away from the NiOx layer by spin coating: first spin coating at a speed of 2500 rpm for 10 s, and then spin coating at a speed of 3500 rpm for 25 s; 5 s before the end of the spin coating process, 200 μL of chlorobenzene is dropped into the center of the substrate, and immediately after the spin coating is stopped, the substrate is transferred to a heating plate at 100°C for annealing for 18 min to obtain a perovskite active layer Cs 0.22 FA 0.78 Pb(I 0.85 Br 0.15 )3.

[0069] Step 19, preparation of a C60 layer with a thickness of 15 nm on the side surface of the perovskite active layer away from the NiOx layer by thermal evaporation; and preparation of a SnO2 layer with a thickness of 20 nm on the surface of the prepared C60 layer by atomic layer deposition.

[0070] Step 20, deposition of an ITO transparent conductive layer with a thickness of 60 nm on one side surface of the SnO2 layer by sputtering.

[0071] Step 21, deposition of an Ag electrode with a thickness of 80 nm on the surface of the transparent conductive layer by thermal evaporation.

[0072] Step 22, MgF2 antireflection layer with thickness of 80 nm was deposited on the far side of the surface of the battery from the first transparent conductive layer by thermal evaporation method, thereby obtaining a crystalline silicon-perovskite stacked battery.

[0073] Example 2 Compared with the steps for preparing the stacked battery in Example 1, the difference lies in that the step 16 for preparing the second interface modification layer is not included, that is, the step 17 is directly carried out after the step 15, that is, the first interface modification liquid is spin-coated on the surface of the NiOx layer at a rotation speed of 3000 rpm for 45 s, and the thin film after spin-coating is subjected to heat treatment in an inert atmosphere, at a temperature of 120°C for 15 minutes, to obtain the first interface modification layer.

[0074] Comparative Example 1 Compared with the steps for preparing the stacked battery in Example 1, the difference lies in that the steps 15 to 17 for preparing the first interface modification layer and the second interface modification layer are not included, that is, the perovskite active layer is directly formed on the surface of the NiOx hole transport layer.

[0075] Comparative Example 2 Compared with the steps for preparing the stacked battery in Example 1, the difference lies in that only the second interface modification layer is formed between the NiOx layer and the perovskite light-absorbing layer, and the first interface modification layer is not prepared, that is: Step 15, graphene oxide is ultrasonically dispersed in a mixed solvent of water and ethanol to obtain a GO dispersion liquid with a concentration of 0.25 mg / mL.

[0076] Step 16, the ultra-thin GO dispersion liquid is spin-coated on the surface of the NiOx layer at a rotation speed of 2000 rpm for 23 s, and the second interface modification layer is obtained by annealing at 120°C, with a thickness of 4 nm.

[0077] Then, the perovskite active layer Cs 0.22 FA 0.78 Pb(I 0.85 Br 0.15 )3 is directly prepared on the surface of the second interface modification layer, and the subsequent steps are the same as in Example 1.

[0078] Comparative Example 3 Compared with the steps for preparing the stacked battery in Example 1, the difference lies in that only the CNT interface modification layer is formed between the NiOx layer and the perovskite light-absorbing layer, and the first interface modification layer and the second interface modification layer are not prepared, that is: Step 15, semiconductor single-walled CNTs are ultrasonically dispersed in a solvent with the assistance of a dispersant (SDBS) to obtain a CNT dispersion liquid with a concentration of 0.2 mg / mL.

[0079] Step 16, spin-coat the CNT dispersion liquid on the surface of the NiOx layer at a speed of 2000 rpm for 25 s, and anneal at 120°C to obtain a CNT interface modification layer with a thickness of 5 nm.

[0080] Then directly prepare a perovskite active layer Cs 0.22 FA 0.78 Pb(I 0.85 Br 0.15 )3 on the surface of the CNT interface modification layer, and the subsequent steps are the same as in Example 1.

[0081] Comparative Example 4 Compared with the steps for preparing the stacked battery in Example 1, the difference lies in that a second interface modification layer and a CNT interface modification layer are sequentially prepared on the surface of the NiOx layer, that is: Step 15, ultrasonically disperse graphene oxide in a mixed solvent of water and ethanol to obtain a GO dispersion liquid with a concentration of 0.25 mg / mL; and ultrasonically disperse semiconductive single-walled CNT in a solvent with the aid of a dispersant (SDBS) to obtain a CNT dispersion liquid with a concentration of 0.2 mg / mL.

[0082] Step 16, spin-coat the ultra-thin GO dispersion liquid on the surface of the NiOx layer at a speed of 2000 rpm for 23 s, and anneal at 120°C to obtain a second interface modification layer with a thickness of 4 nm.

[0083] Step 17, spin-coat the CNT dispersion liquid on the surface of the second interface modification layer at a speed of 2000 rpm for 25 s, and heat-treat the thin film after spin-coating in an inert atmosphere at a temperature of 120°C for 15 minutes to obtain a CNT interface modification layer with a thickness of 5 nm.

[0084] Then directly prepare a perovskite active layer Cs 0.22 FA 0.78 Pb(I 0.85 Br 0.15 )3 on the surface of the CNT interface modification layer, and the subsequent steps are the same as in Example 1.

[0085] The stacked batteries obtained in Examples 1 and 2 and Comparative Examples 1-4 are subjected to performance testing, and the specific testing method is as follows: using a solar simulator and an I-V tester, under 1 standard solar intensity, the electrical performance of the batteries obtained in the above examples and comparative examples is tested by steady-state power output testing, and the test results are shown in Table 1.

[0086] Table 1

[0087] As can be seen from the data in Table 1, compared with Comparative Example 1, in Example 1 and 2, by setting a graphene oxide (GO) and carbon nanotube (CNT) composite layer (first interface modification layer) between the hole transport layers, the oxygen-containing functional groups (such as carboxyl, epoxy) on the surface of GO can form coordination bonds or hydrogen bonds with the defect sites (such as uncoordinated Pb x 2+ , dangling bonds) of the perovskite active layer, inhibit non-radiative recombination, and thus improve the open-circuit voltage (Voc) of the perovskite battery; the oxygen-containing functional groups (such as carboxyl) of GO have hydrophilicity, which can improve the interface wetting problem and improve the subsequent film forming quality; CNT can construct a high-mobility channel, and GO fills the gap between the CNT network, thereby improving the fill factor (FF) of the perovskite battery.

[0088] Compared with Example 2, the setting of the second interface modification layer in Example 1 can further improve the passivation effect on the hole transport layer, better improve the interface defects, and thus improve the battery efficiency.

[0089] In Comparative Example 2, since only a GO modification layer is set, its conductivity is poor, and it is easy to stack, which is not conducive to forming a stable, uniform and conductive interface layer, so the improvement effect on the battery efficiency of the stacked battery is poor.

[0090] In Comparative Example 3, since only a CNT modification layer is set, although its conductivity is good, the defect repair of the hole transport layer is poor, the interface passivation effect is not good, and thus the improvement effect on the battery efficiency of the stacked battery is poor.

[0091] In Comparative Example 4, GO and CNT are independently set in a two-layer structure to form a NiO / GO / CNT / perovskite active layer structure, which introduces new interfaces, each of which is a potential charge trap, leading to increased recombination, especially at the GO and CNT interface and the CNT and perovskite active layer interface. GO and CNT rely only on physical adsorption between them, and their binding force is much weaker than that of a covalent bond or a composite structure connected by a molecular bridge; GO and CNT only rely on van der Waals force for physical contact, and the GO and CNT interface will form a high contact resistance, increasing the recombination; CNT itself is hydrophobic, which will exacerbate the perovskite film forming problem, and the CNT and perovskite active layer interface will have serious recombination. The above multiple reasons cause the battery to have a lower photoelectric conversion efficiency than Comparative Example 2.

[0092] The terms "first", "second", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0093] ​In the description of the specification, the description using the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the particular feature, structure, material or characteristic being described is included in at least one embodiment or example of the present application. The illustrative appearance of the above terms in various places in the specification is not intended to be taken to mean that in all contexts the terms convey the same meaning. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, in non-contradictory cases, those skilled in the art can combine and combine the features of different embodiments or examples described in the specification.

[0094] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary, and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A perovskite cell, characterized in that, Comprising: a first transparent conductive layer, a first charge transport layer, a perovskite active layer, a second charge transport layer and a second transparent conductive layer, one of the first charge transport layer and the second charge transport layer is a hole transport layer, and the other is an electron transport layer; Further comprising: a first interface modification layer, the first interface modification layer is arranged between the hole transport layer and the perovskite active layer, and the first interface modification layer comprises graphene oxide and carbon nanotubes.

2. The perovskite cell according to claim 1, characterized in that, The first interface modification layer further comprises reduced graphene oxide.

3. The perovskite cell of claim 1, wherein, The thickness of the first interface modification layer is 5-10 nm.

4. The perovskite cell according to any one of claims 1 to 3, characterized in that, Further comprising a second interface modification layer, the second interface modification layer is arranged between the first interface modification layer and the hole transport layer, and the second interface modification layer comprises graphene oxide, or comprises graphene oxide and reduced graphene oxide.

5. The perovskite cell according to claim 4, characterized in that, The thickness of the second interface modification layer is 1-4 nm.

6. A method of preparing the perovskite cell according to any one of claims 1 to 5, characterized in that, Comprising the steps of preparing a first transparent conductive layer, a first charge transport layer, a perovskite active layer, a second charge transport layer and a second transparent conductive layer, one of the first charge transport layer and the second charge transport layer is a hole transport layer, and the other is an electron transport layer, further comprising: forming a first interface modification layer between the hole transport layer and the perovskite active layer, the method of forming the first interface modification layer comprising: coating a first interface modification liquid and heat treating to obtain the first interface modification layer.

7. The method of claim 6, wherein, In the first interface modification liquid, the concentration of graphene oxide is 0.05-0.25 mg / mL, and the concentration of carbon nanotubes is 0.05-0.15 mg / mL, And / or, the temperature of the heat treatment is 100-150°C, and the time is 10-30 minutes.

8. The method according to claim 6 or 7, characterized in that, Further comprising: forming a second interface modification layer between the first interface modification layer and the hole transport layer, the method of forming the second interface modification layer comprising: coating a second interface modification liquid and annealing to obtain the second interface modification layer.

9. The method of claim 8, wherein, The concentration of graphene oxide in the second interface modification liquid is 0.1-0.5 mg / mL.

10. A stacked battery characterized by comprising: Comprising: a crystalline silicon bottom cell and a perovskite top cell located on the light-receiving surface of the crystalline silicon bottom cell, the perovskite top cell being the perovskite cell of any one of claims 1-9.

11. A photovoltaic module, characterized by Comprising the perovskite cell of any one of claims 1-5, or comprising the stacked cell of claim 10.

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