CN118175907A - Preparation method of perovskite light absorption layer, solar cell and preparation method thereof - Google Patents

Abstract

The invention relates to a preparation method of a perovskite light absorption layer, a solar cell and a preparation method of the solar cell. The preparation method of the perovskite light absorption layer comprises the following steps: and adopting an evaporation process to jointly deposit organic salt and inorganic salt on the substrate, and adjusting the evaporation ratio of the organic salt and the inorganic salt by controlling the evaporation rate, so as to adjust the ratio of the organic salt and the inorganic salt deposited on the substrate, thereby forming the perovskite light absorption layer comprising the P-type perovskite layer and the N-type perovskite layer which are stacked. According to the preparation method, the P-type perovskite layer and the N-type perovskite layer are formed by adopting an evaporation process, the uniformity of the film layer can be improved, and the evaporation rate is controlled to adjust the evaporation ratio of organic salt and inorganic salt, so that the proportion of the organic salt and the inorganic salt deposited on a substrate is adjusted, the formed P-type perovskite layer and N-type perovskite layer are homogeneous PN junctions, the continuous deposition process is uniform and closely related, and the performance loss caused by interface recombination between different film layers is reduced.

Description

Preparation method of perovskite light absorption layer, solar cell and preparation method thereof

Technical Field

The present invention relates to the photovoltaic field, and in particular to a method for preparing a perovskite light absorption layer, a solar cell and a method for preparing the same.

Background technique

As the third generation of photovoltaic cells, perovskite solar cells have a theoretical photoelectric conversion efficiency of up to 31%, while the current photoelectric conversion efficiency is about 26%. Most of the most efficient perovskite cells are currently prepared on a small area of glass using a one-step solution spin coating method, which cannot achieve large-area uniform preparation, hindering their industrialization process. Walsh used spin coating to prepare P-type perovskite films and N-type perovskite films respectively, and the cell efficiency reached 21%. However, there are serious problems of interface recombination and poor uniformity of large-area preparation when using the solution method to prepare P-type perovskite films and N-type perovskite films respectively, which affects the performance of the cell such as efficiency.

Summary of the invention

Based on this, it is necessary to provide a method for preparing a perovskite light absorption layer, a solar cell and a method for preparing the same, so as to solve the problem of serious interface recombination between P-type perovskite film and N-type perovskite film and poor uniformity in large-area preparation.

The first aspect of the present invention is to provide a method for preparing a perovskite light absorbing layer, the scheme is as follows:

A method for preparing a perovskite light absorbing layer comprises the following steps:

A perovskite light absorbing layer is deposited on a substrate by an evaporation process, wherein the evaporation source includes an organic salt and an inorganic salt. The evaporation rate of the evaporation source is controlled to adjust the evaporation ratio of the organic salt and the inorganic salt, thereby adjusting the ratio of the organic salt and the inorganic salt deposited on the substrate to form the perovskite light absorbing layer including a stacked P-type perovskite layer and an N-type perovskite layer.

In one embodiment, the molecular formula of the organic salt is RX _n , wherein R is selected from at least one of methyl amidino and methylamino, X is selected from at least one of Cl, Br, and I, and n is in stoichiometric form.

In one embodiment, the inorganic salt has a molecular formula of QX' _n , wherein Q is selected from at least one of Cs, Pb, and Sn, X' is selected from at least one of Cl, Br, and I, and n conforms to stoichiometry.

In one embodiment, each of the evaporation sources is disposed on a different heat source, and the heating temperature of each of the heat sources is independently controlled to independently control the evaporation rate of each of the evaporation sources.

In one embodiment, in a first stage of the evaporation process, a first type of perovskite layer is deposited at a first evaporation rate of each evaporation source;

In the second stage of the evaporation process, the evaporation rates of one or more evaporation sources are controlled to gradually change to respective second evaporation rates, so that the perovskite layer gradually transitions from the first type perovskite layer to the second type perovskite layer;

The first type perovskite layer is a P-type perovskite layer, and the second type perovskite layer is an N-type perovskite layer; or, the first type perovskite layer is an N-type perovskite layer, and the second type perovskite layer is a P-type perovskite layer.

In one embodiment, the first type perovskite layer is a P-type perovskite layer, the second type perovskite layer is an N-type perovskite layer, and the temperature of the substrate in the second stage is controlled to be higher than the temperature of the substrate in the first stage; or

The first type perovskite layer is an N-type perovskite layer, the second type perovskite layer is a P-type perovskite layer, and the temperature of the substrate in the second stage is controlled to be lower than the temperature of the substrate in the first stage.

The second aspect of the present invention is to provide a method for preparing a solar cell, the scheme is as follows:

A method for preparing a solar cell comprises the following steps:

Depositing the perovskite light absorbing layer on a substrate by the preparation method of the perovskite light absorbing layer;

An electrode layer is formed on the perovskite light absorbing layer.

In one embodiment, the method for preparing a solar cell further comprises the following steps:

A hole transport layer is formed by deposition using an evaporation process, and the hole transport layer is located between the electrode layer and the P-type perovskite layer.

In one embodiment, the method for preparing a solar cell further comprises the following steps:

An electron transport layer is formed by deposition using an evaporation process, and the electron transport layer is located between the substrate and the N-type perovskite layer.

The third aspect of the present invention is to provide a solar cell, the scheme is as follows:

A solar cell is prepared by the method for preparing a solar cell.

Compared with the traditional solution, the above-mentioned method for preparing the perovskite light absorption layer, the solar cell and the preparation method thereof have the following beneficial effects:

The above-mentioned method for preparing the perovskite light absorption layer adopts an evaporation process to form a P-type perovskite layer and an N-type perovskite layer. Compared with the solution method, the uniformity of the film layer can be improved, and the ratio of evaporation of organic salts and inorganic salts can be adjusted by controlling the evaporation rate, thereby adjusting the ratio of organic salts and inorganic salts deposited on the substrate. The formed P-type perovskite layer and N-type perovskite layer are homogeneous PN junctions, and the built-in electric field generated by them separates and extracts electrons and holes, and there is no need to set up an additional carrier transport layer. The continuous deposition process is uniform and closely connected, and it can be regarded as a whole, reducing the performance loss caused by interface recombination between different film layers.

The method for preparing the solar cell includes the method for preparing the perovskite light absorption layer, thereby being able to obtain corresponding beneficial effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a solar cell according to an embodiment;

FIG. 2 is a schematic structural diagram of a solar cell according to another embodiment.

Detailed ways

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and/or" used herein includes any and all combinations of one or more of the related listed items.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

A method for preparing a perovskite light absorbing layer according to an embodiment of the present invention comprises the following steps:

A perovskite light absorbing layer is deposited on a substrate by an evaporation process, wherein the evaporation source includes an organic salt and an inorganic salt. By controlling the evaporation rate of the evaporation source and adjusting the evaporation ratio of the organic salt and the inorganic salt, the ratio of the organic salt and the inorganic salt deposited on the substrate is adjusted to form a perovskite light absorbing layer including a stacked P-type perovskite layer and an N-type perovskite layer.

The above-mentioned method for preparing the perovskite light absorption layer adopts an evaporation process to form a P-type perovskite layer and an N-type perovskite layer. Compared with the solution method, the uniformity of the film layer can be improved, and the ratio of evaporation of organic salts and inorganic salts can be adjusted by controlling the evaporation rate, thereby adjusting the ratio of organic salts and inorganic salts deposited on the substrate. The formed P-type perovskite layer and N-type perovskite layer are homogeneous PN junctions, and the built-in electric field generated by them separates and extracts electrons and holes, and there is no need to set up an additional carrier transport layer. The continuous deposition process is uniform and closely connected, and it can be regarded as a whole, reducing the performance loss caused by interface recombination between different film layers.

The preparation method controls the evaporation rate, adjusts the evaporation ratio of organic salt and inorganic salt, and continuously evaporates the P-type perovskite layer and the N-type perovskite layer, thereby shortening the battery preparation cycle and facilitating industrial production.

The molecular formula of the organic salt is RX _n , in which R can be but is not limited to at least one of FA (carbamimidoyl, CH(NH ₂ ) ₂ ⁺ ) and MA (methylamino, CH ₃ NH ₃ ⁺ ), X is selected from at least one of Cl, Br, and I, and n conforms to stoichiometry.

Furthermore, the organic salt is selected from at least one of FAI, FABr, MAI, MABr and MACl.

The inorganic salt has a molecular formula of QX' _n , wherein Q is selected from at least one of Cs, Pb and Sn, X' is selected from at least one of Cl, Br and I, and n conforms to the stoichiometric ratio.

Furthermore, the inorganic salt is at least one selected from the group consisting of CsI, PbI ₂ , PbBr ₂ , PbCl, CsBr, CsCl, SnCl ₄ , SnI ₄ , and SnBr ₄ .

In one example, the evaporation rate of the organic salt and the inorganic salt is controlled by controlling the temperature of the evaporation process, thereby adjusting the evaporation ratio of the organic salt and the inorganic salt. For example, compared with N-type perovskite, the deposition rate of the main A-site precursor material of P-type perovskite is slow or the deposition rate of the main X-site precursor material is fast.

In one example, each evaporation source is disposed on a different heat source, and the heating temperature of the different heat sources is independently controlled to independently control the evaporation rate of the different evaporation sources.

For example, the organic salts are MAI and MACl, the inorganic salts are PbI ₂ and PbCl ₂ , MAI, MACl, PbI ₂ and PbCl ₂ are respectively set on four heat sources, and the heating temperatures of different heat sources are independently controlled, so that different evaporation sources can be adjusted independently.

In one example, in a first stage of the evaporation process, a first type of perovskite layer is deposited at a first evaporation rate of each evaporation source;

In the second stage of the evaporation process, the evaporation rates of one or more evaporation sources are controlled to gradually change to respective second evaporation rates, so that the perovskite layer gradually transitions from the first type perovskite layer to the second type perovskite layer;

The first type perovskite layer is a P-type perovskite layer, and the second type perovskite layer is an N-type perovskite layer; or, the first type perovskite layer is an N-type perovskite layer, and the second type perovskite layer is a P-type perovskite layer.

The first and second stages of the evaporation process are performed continuously. The evaporation rate of the evaporation source changes continuously. In this way, the element concentration at the PN junction changes in a gradient, avoiding serious phase separation at the PN junction during the subsequent film formation process.

In one example, the first type perovskite layer is a P-type perovskite layer, the second type perovskite layer is an N-type perovskite layer, and the temperature of the substrate in the second stage is controlled to be higher than the temperature of the substrate in the first stage. By increasing the temperature of the substrate in the second stage, the N-type degree of the N-type perovskite layer can be made better.

In one example, the first type perovskite layer is an N-type perovskite layer, the second type perovskite layer is a P-type perovskite layer, and the temperature of the substrate in the second stage is controlled to be lower than the temperature of the substrate in the first stage. By lowering the temperature of the substrate in the second stage, the P-type degree of the P-type perovskite layer can be made better.

The P-type perovskite layer and the N-type perovskite layer form a homogeneous PN junction, and the atomic or group composition of the perovskite material is consistent, but the atomic or group ratio is different. The molecular formula of the perovskite material is ABX _3. Wherein, A is a monovalent cation, including but not limited to at least one of cesium ion, rubidium ion, potassium ion, methylamine ion, formamidine ion, methylenediamine ion, benzamidine cation and guanidine cation. B is a divalent cation, including but not limited to at least one of lead ion, copper ion, zinc ion, gallium ion, tin ion and calcium ion. X is a monovalent anion, including but not limited to at least one of fluoride ion, chloride ion, bromide ion, iodide ion, thiocyanate ion, tetrafluoroborate ion, hexafluorophosphate ion, formate ion and acetate ion.

In one example, the band gap of the P-type perovskite layer is 1.40eV~2.3eV.

In one example, the band gap of the N-type perovskite layer was 1.40eV~2.3eV.

In one example, the thickness of the P-type perovskite layer is 300nm~600nm.

In one example, the thickness of the N-type perovskite layer is 300nm~600nm.

Furthermore, the present invention also provides a method for preparing a solar cell, comprising the following steps:

Depositing a perovskite light absorbing layer on a substrate by any of the above-mentioned methods for preparing a perovskite light absorbing layer;

An electrode layer is formed on the perovskite light absorbing layer.

The above preparation method uses an evaporation process to form a P-type perovskite layer and an N-type perovskite layer, which can improve the uniformity of the film layer, and by controlling the evaporation rate, adjust the ratio of the evaporation of organic salts and inorganic salts, thereby adjusting the ratio of organic salts and inorganic salts deposited on the substrate. The formed P-type perovskite layer and N-type perovskite layer are homogeneous PN junctions, and the built-in electric field generated separates and extracts electrons and holes, and no additional carrier transport layer is required. The continuous deposition process is uniform and closely connected, and can be regarded as a whole, reducing the performance loss caused by interface recombination between different film layers.

The preparation method controls the evaporation rate, adjusts the evaporation ratio of organic salt and inorganic salt, and continuously evaporates the P-type perovskite layer and the N-type perovskite layer, thereby shortening the battery preparation cycle and facilitating industrial production.

The solar cell can be a single-layer perovskite cell or a stacked-layer cell.

For example, the solar cell 100 shown in FIG1 is a single-layer perovskite cell, which includes a stacked substrate 110, a perovskite light absorbing layer 120, and an electrode layer 130. The perovskite light absorbing layer 120 includes a P-type perovskite layer 121 and an N-type perovskite layer 122.

When the solar cell is a perovskite single-layer cell, the material of the substrate 110 can be, but is not limited to, one or more of oxides such as indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), indium-doped zinc oxide (IZO), fluorine-doped tin oxide (FTO), indium tungsten oxide (IWO), and indium cerium oxide (ICO).

Among them, the tandem cells are, for example, perovskite/crystalline silicon tandem cells, all-perovskite tandem cells, perovskite/organic tandem cells, perovskite/CIGS tandem cells, perovskite/CdTe tandem cells, perovskite/GaAs tandem cells, etc.

For example, the solar cell 200 shown in FIG2 is a perovskite/crystalline silicon stacked cell, which includes an anti-reflection layer 270, a second transparent conductive layer 260, a buffer layer 250, a hole transport layer 240, a P-type perovskite layer 232, an N-type perovskite layer 231, an electron transport layer 220, a composite layer 219, a first doping layer 214, a first amorphous silicon layer 212, a single crystal silicon substrate 211, a second amorphous silicon layer 213, a second doping layer 216, and a transparent electrode layer 217. A first grid line 218 is arranged on the anti-reflection layer 270, and a second grid line 280 is arranged on the transparent electrode layer 217. The P-type perovskite layer 232 and the N-type perovskite layer 231 constitute a perovskite light absorption layer 230.

The perovskite homogeneous PN junction prepared by the evaporation process can realize the transmission of carriers, and there is no need to set up an additional carrier transport layer.

In order to further improve the hole transport effect, in one example, the method for preparing a solar cell further includes the following steps:

A hole transport layer is formed, and the hole transport layer is located between the electrode layer and the P-type perovskite layer.

Optionally, the material of the hole transport layer can be, but is not limited to, NiO _x (nickel oxide), CuSCN (cuprous thiocyanate), MoO _x (molybdenum oxide), CuI (cuprous iodide), CuO _x (copper oxide), V ₂ O ₅ (vanadium pentoxide), MoS ₂ (molybdenum disulfide), MnS ₂ (manganese disulfide), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid)), Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene), Spiro-TTB (2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'-bifluorene), (MeO-)2PACz ([2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), (MeO-)4PACz ([4-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), One or more of: [(1,2-butyl)phosphonic acid), F4-TCNQ (2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone), and P3HT (poly 3-hexylthiophene).

In one example, the thickness of the hole transport layer is 1 nm to 200 nm. Further, in one example, the thickness of the hole transport layer is 10 nm to 100 nm. In some specific examples, the thickness of the hole transport layer is 5 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc.

Optionally, the preparation process of the hole transport layer can be but is not limited to evaporation, magnetron sputtering, atomic layer deposition, electrochemical deposition, molecular beam evaporation, dip coating, spin coating, blade coating, slit coating, rod coating and inkjet printing.

In one example, the hole transport layer is prepared by evaporation. Due to the different preparation methods, the hole transport layer prepared by the wet method and the perovskite light absorption layer prepared by the dry method will have interface incompatibility, resulting in additional defects and thus performance loss. In this example, the hole transport layer is prepared by evaporation, which can reduce the interface recombination between the hole transport layer and the perovskite light absorption layer and reduce the loss of battery performance.

In order to further improve the electron transmission effect, in one example, the method for preparing a solar cell further includes the following steps:

An electron transport layer is formed, and the electron transport layer is located between the substrate and the N-type perovskite layer.

Optionally, the material of the electron transport layer may be one or more of but not limited to ZnO (zinc oxide), SnO ₂ (tin oxide), TiO ₂ (titanium dioxide), SrTiO ₃ (strontium titanate), Zn ₂ SnO ₄ (zinc stannate), ZrO ₂ (zirconium dioxide), Al ₂ O ₃ (aluminum oxide), WO ₃ (tungsten trioxide), CeO _x (cesium oxide), CdS (cadmium sulfide), CdSe (cadmium selenide), BaSnO ₃ (barium stannate), Nb ₂ O ₅ (niobium pentoxide), C ₆₀ (fullerene), and PCBM (fullerene derivative).

In one example, the thickness of the electron transport layer is 1 nm to 30 nm. Further, in one example, the thickness of the electron transport layer is 5 nm to 20 nm. In some specific examples, the thickness of the electron transport layer is 2 nm, 5 nm, 8 nm, 12 nm, 15 nm, 18 nm, 20 nm, 22 nm, 25 nm, 27 nm, 29 nm, 30 nm, etc.

Optionally, the preparation process of the electron transport layer can be but is not limited to evaporation, magnetron sputtering, atomic layer deposition, electrochemical deposition, molecular beam evaporation, dip coating, spin coating, blade coating, slit coating, rod coating and inkjet printing.

In one example, the electron transport layer is prepared by evaporation. Due to the different preparation methods, the electron transport layer prepared by the wet method and the perovskite light absorption layer prepared by the dry method will be incompatible at the interface, resulting in additional defects and thus causing performance loss. In this example, the electron transport layer is prepared by evaporation, which can reduce the interface recombination between the electron transport layer and the perovskite light absorption layer and reduce the loss of battery performance.

Optionally, the material of the electrode layer may be, but is not limited to, one or more of metals such as Au, Ag, and Cu.

Furthermore, the present invention also provides a solar cell, which is prepared by any of the preparation methods in the above examples.

The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following specific embodiments.

Example 1

As shown in FIG. 1 , this embodiment provides a method for preparing a solar cell 100, comprising the following steps:

Step 1: Use ITO conductive glass as the substrate 110, whose sheet resistance is 1Ω/sq and thickness is 20nm.

Step 2: Using an evaporation process to deposit a perovskite light absorbing layer 120 on the substrate 110. The evaporation source includes organic salt and inorganic salt, the organic salt is MAI and MACl, and the inorganic salt is PbI ₂ and PbCl ₂ , and different evaporation sources are respectively installed on different heat sources.

In the first stage, the temperature of the substrate is controlled to be 0°C, and the temperature of each heat source is controlled to make the evaporation rate of MAI, MACl and PbI ₂ 1.5Å/s, and the evaporation rate of PbCl ₂ 0, and a P-type perovskite layer 121 is deposited on the substrate, with a composition of MAPbI ₃ and a thickness of 300nm.

In the second stage, the substrate is heated to 50°C and the temperature of the heat source is adjusted to keep the evaporation rate of MAI and MACl at 1.5Å/s, the evaporation rate of _PbI2 is reduced from 1.5Å/s to 0.9A/s, and the evaporation rate of _PbCl2 is increased from 0 to 0.6A/s. An N-type perovskite layer 122 is deposited on the above-mentioned P-type perovskite layer 121, with a composition of _{MAPbIxCl1 -x} and a thickness of 300nm.

Step 3: Deposit silver on the N-type perovskite layer 122 using an evaporation process to form an electrode layer 130 with a thickness of 70 nm.

Step 4, annealing the perovskite cell obtained in step 3 at 100° C. for 15 minutes.

Example 2

As shown in FIG. 2 , this embodiment provides a method for preparing a solar cell, comprising the following steps:

Step 1: Select N-type single crystal silicon, perform RCA cleaning, and then use metal-assisted chemical etching to prepare a porous structure on the surface of the N-type single crystal silicon to obtain porous silicon. The etching uses a mixed solution composed of HF, AgNO ₃ and H ₂ O ₂ , and then uses HNO ₃ for cleaning after etching.

Step 2, immerse the porous silicon in an acid solution at 10°C, the acid solution comprising HF and HNO3 in a volume ratio of 1: ₃ . After removing the porous silicon on the surface, place it in a NaOH solution at 70°C-90°C for texturing to obtain a top pyramid structure and a bottom inverted pyramid structure, wherein the angle between the top pyramid structure and the silicon surface is 60°, the depth is 1μm, and the angle between the bottom inverted pyramid structure and the silicon surface is 25°, the depth is 1μm, and the single crystal silicon substrate 211 is obtained.

Step 3, using PECVD (plasma enhanced chemical vapor deposition) process to deposit a-Si:H (hydrogenated amorphous silicon) on the front and back sides of the single crystal silicon substrate 211, respectively, to obtain a first amorphous silicon layer 212 and a second amorphous silicon layer 213, the deposition temperature is 200°C, and the deposition thickness is 5nm.

Step 4: deposit boron-doped a-Si:H on the first amorphous silicon layer 212 using a PECVD process to form a first doped layer 214, with a deposition temperature of 200° C. and a deposition thickness of 12 nm.

Step 5: Deposit phosphorus-doped a-Si:H on the second amorphous silicon layer 213 using a PECVD process to form a second doped layer 216. The deposition temperature is 200° C. and the deposition thickness is 6 nm.

Step 6: Deposit ITO on the second doping layer 216 by magnetron sputtering process to form a first transparent conductive layer 4 with a deposition thickness of 110 nm and a sheet resistance of 120Ω/sq.

Step 7: deposit silver on the first transparent conductive layer 4 at low temperature by using an evaporation process to form a first gate line 218 .

Step 8: Deposit IZO on the first doping layer 214 by magnetron sputtering to form a composite layer 219 with a deposition thickness of 15 nm.

Step 9: C60-COOH-SAM is deposited on the composite layer 219 by an evaporation process to form an electron transport layer 220 with a thickness of 15 nm.

Step 10: using an evaporation process to deposit a perovskite light absorbing layer 230 on the electron transport layer 220. The evaporation source includes organic salts and inorganic salts, the organic salts are FAI, FABr, MACl and FACl, and the inorganic salts are _PbBr2 , _PbI2 and CsI.

In the first stage, the temperature of the substrate is controlled to be 100°C, and the temperatures of the heat sources are controlled to make the evaporation rate ratio of the organic salts FAI, FABr, MACl, and FACl be 3:2:1.5:3, and the evaporation rate ratio of the inorganic _{salts PbBr2} , _PbI2 , and CsI be 1:19:1, _{and an N-type perovskite layer 231 is deposited on the electron transport layer 220, with a composition of FA0.8MA0.15Cs0.05Pb(I0.75Br0.1Cl0.15 ) 3 and a thickness} of 500nm.

In the second stage, the temperature of the substrate is adjusted to 80°C, and the temperature of each heat source is controlled to gradually adjust the evaporation rate of each evaporation source until the evaporation rate ratio of the organic salts FAI, FABr, MACl, and FACl is adjusted to 1:1:4.5:3, and the evaporation rate ratio of the inorganic salts _PbBr2 , _PbI2 , and CsI is adjusted to 12:1:0.5, and a P-type perovskite layer 232 is deposited on the above-mentioned N-type perovskite layer 231, with a composition of FA _0.5 MA _0.45 Cs _0.05 Pb(I _0.85 Br _0.1 Cl _0.05 ) ₃ and a thickness of 500nm. Step 11, Spiro-TTB and F6-TCNNQ are co-evaporated by an evaporation process, and a hole transport layer 240 is deposited on the P-type perovskite layer 232 with a thickness of 25nm.

Step 12: Deposit SnO ₂ on the hole transport layer 240 by evaporation process to form a buffer layer 250 , with a deposition thickness of about 20 nm.

Step 13: Deposit IZO on the buffer layer 250 by magnetron sputtering process to form a second transparent conductive layer 260, with a deposition thickness of about 100 nm.

Step 14: Deposit silver on the second transparent conductive layer 260 through a mask using an evaporation process to form a second gate line 280 with a thickness of about 400 nm.

Step 14: MgF _x is deposited on the entire surface by using an evaporation process to form an anti-reflection layer 270 , with a deposition thickness of about 120 nm.

Comparative Example 1

The difference between this comparative example and Example 1 is that in step 2, both the P-type perovskite layer and the N-type perovskite layer are prepared by a conventional spin coating process.

Comparative Example 2

The difference between this comparative example and Example 2 is that in step 10, both the P-type perovskite layer and the N-type perovskite layer are prepared by a conventional spin coating process.

The performance of the solar cells prepared in Examples 1-2 and Comparative Examples 1-2 was tested, and the results are shown in Table 1.

Table 1 Performance test results of solar cells of Examples 1-2 and Comparative Examples 1-2

It can be seen from the results in Table 1 that Examples 1-2 form the perovskite film layer by evaporation process, and adjust the ratio of evaporation of organic salt and inorganic salt by changing the evaporation temperature, and continuously deposit to form the P-type perovskite layer and the N-type perovskite layer. Compared with Comparative Examples 1-2 using the traditional spin coating process, the in vivo recombination of carriers is reduced, the open circuit voltage is significantly improved, and the fill factor and conversion efficiency are also improved.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description can be used to interpret the content of the claims.

Claims (10)

1. A method for preparing a perovskite light absorbing layer, characterized in that it comprises the following steps: A perovskite light absorbing layer is deposited on a substrate by an evaporation process, wherein the evaporation source includes an organic salt and an inorganic salt. The evaporation rate of the evaporation source is controlled to adjust the evaporation ratio of the organic salt and the inorganic salt, thereby adjusting the ratio of the organic salt and the inorganic salt deposited on the substrate to form the perovskite light absorbing layer including a stacked P-type perovskite layer and an N-type perovskite layer. 2. The method for preparing a perovskite light absorbing layer according to claim 1, wherein the molecular formula of the organic salt is RX _n , wherein R is selected from at least one of a methyl amidine group and a methylamine group, X is selected from at least one of Cl, Br, and I, and n conforms to the stoichiometric ratio. 3. The method for preparing a perovskite light absorbing layer according to claim 1, characterized in that the inorganic salt has a molecular formula of _QX'n , wherein Q is selected from at least one of Cs, Pb, and Sn, X' is selected from at least one of Cl, Br, and I, and n conforms to stoichiometry. 4. The method for preparing a perovskite light absorbing layer according to claim 1, characterized in that each of the evaporation sources is respectively arranged on a different heat source, and the heating temperature of the different heat sources is independently controlled to independently control the evaporation rate of the different evaporation sources. 5. The method for preparing a perovskite light absorbing layer according to any one of claims 1 to 4, characterized in that, in the first stage of the evaporation process, a first type of perovskite layer is deposited at a first evaporation rate of each evaporation source; In the second stage of the evaporation process, the evaporation rates of one or more evaporation sources are controlled to gradually change to respective second evaporation rates, so that the perovskite layer gradually transitions from the first type perovskite layer to the second type perovskite layer; The first type perovskite layer is a P-type perovskite layer, and the second type perovskite layer is an N-type perovskite layer; or, the first type perovskite layer is an N-type perovskite layer, and the second type perovskite layer is a P-type perovskite layer. 6. The method for preparing a perovskite light absorption layer according to claim 5, characterized in that the first type of perovskite layer is a P-type perovskite layer, the second type of perovskite layer is an N-type perovskite layer, and the temperature of the substrate in the second stage is controlled to be higher than the temperature of the substrate in the first stage; or The first type perovskite layer is an N-type perovskite layer, the second type perovskite layer is a P-type perovskite layer, and the temperature of the substrate in the second stage is controlled to be lower than the temperature of the substrate in the first stage. 7. A method for preparing a solar cell, characterized in that it comprises the following steps: Depositing the perovskite light absorbing layer on a substrate by the preparation method according to any one of claims 1 to 6; An electrode layer is formed on the perovskite light absorbing layer. 8. The method for preparing a solar cell according to claim 7, characterized in that the method for preparing a solar cell further comprises the following steps: A hole transport layer is formed by deposition using an evaporation process, and the hole transport layer is located between the electrode layer and the P-type perovskite layer. 9. The method for preparing a solar cell according to claim 7 or 8, characterized in that the method for preparing a solar cell further comprises the following steps: An electron transport layer is formed by deposition using an evaporation process, and the electron transport layer is located between the substrate and the N-type perovskite layer. 10. A solar cell, characterized in that it is prepared by the preparation method according to any one of claims 7 to 9.