Preparation method and application of high-quality perovskite layer

Abstract

The invention provides a preparation method and application of a high-quality perovskite layer, and belongs to the technical field of laminated photovoltaic cells, and the preparation method specifically comprises the steps: placing a substrate on the surface of a substrate, and preparing an inorganic layer on the surface of the substrate through evaporation; in the evaporation process, the evaporation angle theta is controlled to be larger than or equal to 15 degrees and smaller than 60 degrees by adjusting the angle of an evaporation source, the angle of a substrate or / and the fluctuation angle of the surface appearance of the substrate, so that the inorganic layer which is controllable in growth direction and adjustable in column spacing and has the nanocolumn appearance is obtained; and thermally evaporating the organic halide on the surface of the inorganic layer or spin-coating the organic halide solution, and annealing to obtain the high-quality perovskite layer. According to the invention, by controlling the evaporation angle of the inorganic layer, the growth direction-controllable and column spacing-adjustable inorganic material nano-columns are realized, so that the uniform permeation of organic halide in the process of thermally evaporating the organic halide or spin-coating the organic halide mixture solution in the second step is ensured, the film quality of the perovskite layer is improved, the residual stress in the film is reduced, and the performance of the perovskite film is improved. Therefore, the energy conversion efficiency of the perovskite solar cell is improved, the preparation method is simple, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of laminated photovoltaic cells, and in particular relates to a preparation method of a high-quality perovskite layer and an application thereof. Background Art

[0002] Because perovskite materials have an adjustable band gap of 1.48 to 2.23 electron volts and excellent light absorption capabilities, they are often used in combination with crystalline silicon solar cells. The silicon-based perovskite double-end stacked solar cells formed by this combination have developed extremely rapidly, and their maximum conversion efficiency has soared to 34.6% in a few years. The core structure of the silicon-based perovskite double-end stacked solar cell includes a wide-bandgap perovskite top cell and a narrow-bandgap silicon base cell. The perovskite top cell is responsible for absorbing high-energy photons, while the silicon base cell is used to absorb low-energy photons. This stacked design can effectively improve the overall light absorption efficiency.

[0003] In order to achieve conformal coverage of perovskite on a silicon substrate with a large-scale velvet surface (pyramids > 2μm), a two-step method is generally used for synthesis. In the first step, taking the synthesis of lead iodide film containing cesium halide as an inorganic skeleton as an example, a conformal inorganic support (also called a template) is formed on the substrate by co-evaporating cesium halide CsX (X = Br, I) and lead iodide (PbI2); in the second step, an organic halide is thermally evaporated on the surface of the co-evaporated film, or an organic halide mixture solution is spin-coated, and annealed at 150°C in air to induce mutual diffusion of precursors, and finally form perovskite.

[0004] When synthesizing perovskite film by two-step method, the ion migration ability of lead iodide film containing cesium halide is weak, resulting in poor uniformity of perovskite film; and there is no preferential orientation during the growth of perovskite film, and the chaotic orientation growth will cause residual stress in the film, which will affect the performance and stability of the device. At the same time, since the organic salt will quickly react with the lead iodide on the surface of the lead iodide film to form a dense perovskite layer, it prevents organic cations from penetrating into the unreacted area at the bottom of the lead iodide film, resulting in insufficient reaction between the inorganic skeleton and the organic salt, and a large amount of unreacted lead iodide remains at the bottom, which seriously deteriorates the device performance and accelerates the degradation of the device. Summary of the invention

[0005] In view of the problems existing in the above-mentioned existing two-step synthesis process of perovskite, the present invention provides a method for preparing a high-quality perovskite layer and its application. By controlling the evaporation angle of the inorganic layer, inorganic material nanocolumns with controllable growth direction and adjustable column spacing are achieved, which helps to ensure the uniform penetration of organic halides during the second step of thermal evaporation of organic halides or spin coating of organic halide mixture solution, so as to improve the film quality of the perovskite layer, reduce the residual stress in the film, and further improve the energy conversion efficiency of the perovskite solar cell. The preparation method is simple and low-cost.

[0006] In order to achieve the above purpose, the technical method adopted by the present invention is as follows:

[0007] A method for preparing a high-quality perovskite layer comprises the following steps:

[0008] Step 1, placing a substrate on a substrate surface, and preparing an inorganic layer on the substrate surface by evaporation; during the evaporation process, the evaporation source angle, the substrate angle, and / or the undulating angle of the substrate surface morphology are adjusted to control the evaporation angle to be 15°≤θ<60°, so as to obtain an inorganic layer with a nano-column morphology with controllable growth direction and adjustable column spacing;

[0009] Step 2: thermally evaporate an organic halide or spin-coat an organic halide solution on the surface of the inorganic layer, and obtain a high-quality perovskite layer through annealing.

[0010] Furthermore, the material of the inorganic layer is at least one of lead iodide, lead bromide, lead chloride, cesium bromide, cesium iodide, cesium chloride, and cesium fluoride.

[0011] Furthermore, in step 2, the annealing temperature is 100-170° C., the duration is 15-30 min, and the humidity of the annealing environment is 30%-70%.

[0012] Furthermore, the organic halide is formamidine iodide, formamidine bromide, formamidine chloride, methylamine iodide, methylamine bromide or methylamine chloride.

[0013] Furthermore, the concentration of the organic halide solution is 0.5-1 mol / mL.

[0014] The present invention also provides an application of the high-quality perovskite layer in a perovskite solar cell.

[0015] Furthermore, the perovskite solar cell is a perovskite single junction cell or a perovskite / silicon-based tandem cell.

[0016] Furthermore, the perovskite single-junction cell includes a substrate, a hole transport layer, a high-quality perovskite layer, an electron transport layer and a surface electrode stacked in sequence from bottom to top; wherein the thickness of the high-quality perovskite layer is 300 to 500 nm.

[0017] Furthermore, the perovskite / silicon-based stacked cell includes a silicon substrate cell, a hole transport layer, a high-quality perovskite layer, an interface passivation layer, an electron transport layer, a buffer layer, a window layer, a surface electrode and an anti-reflection layer stacked in sequence from bottom to top; wherein the thickness of the high-quality perovskite layer is 600 to 700 nm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention proposes a method for preparing a high-quality perovskite layer and its application. By controlling the evaporation angle of the inorganic layer, inorganic material nanocolumns with controllable growth direction and adjustable column spacing (from angstroms to nanometers) are obtained. The nanocolumn structure provides a vertical channel for the penetration / diffusion of organic halide cations in the second step, which helps to ensure the uniform penetration of organic halide, accelerate the diffusion of organic halide cations, and then accurately adjust the reaction rate of inorganic substances and organic halide cations, improve the ion uniformity and film quality inside the perovskite layer, avoid the problems of slow diffusion, uneven diffusion and incomplete reaction of organic salts in the inorganic layer in the traditional two-step method, and thus improve the energy conversion efficiency of perovskite solar cells;

[0020] 2. The present invention can limit the inorganic layer to grow in an island-like growth mode by controlling the evaporation angle of the inorganic layer, thereby ensuring that the inorganic layer has a uniform thin film growth orientation, which is beneficial to alleviating the residual stress generated by orientation disorder during the thin film growth process;

[0021] 3. The present invention does not require the use of other passivating agents, additives, and masks, thereby ensuring the environmental friendliness of the preparation process and having the advantages of a simple preparation method and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The SEM (scanning electron microscope) images of the inorganic layers obtained in Example 1 and Comparative Example 1; wherein (a) is a surface SEM image of the inorganic layer of Example 1; (b) is a cross-sectional SEM image of the inorganic layer of Example 1; (c) is a surface SEM image of the inorganic layer of Comparative Example 1; (d) is a cross-sectional SEM image of the inorganic layer of Comparative Example 1;

[0024] Figure 2 Schematic diagram of residual stress distribution of the perovskite layer obtained in Example 1 and Comparative Example 1;

[0025] Figure 3 A schematic diagram of the structure of a perovskite single-junction solar cell provided in Example 1, Comparative Example 1, Example 2, Comparative Example 2 and Example 4;

[0026] Figure 4 A schematic diagram of the structure of a perovskite / silicon-based tandem solar cell provided in Example 3 and Comparative Example 3;

[0027] Figure 5 XRD (X-ray diffraction) diagrams of the perovskite layer of the inorganic layer prepared based on different evaporation angles in Comparative Example 1 and Example 1;

[0028] Figure 6 Performance box diagram of the perovskite single-junction solar cell provided in Example 1 and Comparative Example 1; wherein (a) is the open circuit voltage; (b) is the short circuit current density; (c) is the fill factor; (d) is the photoelectric conversion efficiency;

[0029] Figure 7 JV diagrams of perovskite single junction solar cells provided for Example 1 and Comparative Example 1;

[0030] Figure 8 JV diagrams of perovskite single junction solar cells provided for Example 2 and Comparative Example 2;

[0031] Fig. 9 JV diagrams of perovskite / silicon-based tandem solar cells provided for Example 3 and Comparative Example 3;

[0032] Fig.10 EQE (external quantum efficiency) diagram of the perovskite / silicon-based tandem solar cell provided in Example 3;

[0033] Fig.11 These are SEM images of the inorganic layers obtained in Example 3 and Comparative Example 3; wherein, (a) is a cross-sectional SEM image of the inorganic layer of Example 3; and (b) is a cross-sectional SEM image of the inorganic layer of Comparative Example 3. DETAILED DESCRIPTION

[0034] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. All raw materials of the present invention are not particularly limited in their sources, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0035] A method for preparing a high-quality perovskite layer comprises the following steps:

[0036] Step 1, placing a substrate on a substrate surface, and preparing an inorganic layer on the substrate surface by evaporation; during the evaporation process, the evaporation source angle, the substrate angle, and / or the undulating angle of the substrate surface morphology are adjusted to control the evaporation angle to be 15°≤θ<60°, so as to obtain an inorganic layer with a nano-column morphology with controllable growth direction and adjustable column spacing;

[0037] Step 2: thermally evaporate an organic halide or spin-coat an organic halide solution on the surface of the inorganic layer, and obtain a high-quality perovskite layer through annealing.

[0038] Furthermore, the material of the inorganic layer is at least one of lead iodide, lead bromide, lead chloride, cesium bromide, cesium iodide, cesium chloride, and cesium fluoride. Specific implementation Lead iodide and CsX (X=Cl / I / Br / F) are used as evaporation sources of the inorganic layer.

[0039] Furthermore, in step 2, the annealing temperature is 100-170° C., the duration is 15-30 min, and the humidity of the annealing environment is 30%-70%.

[0040] Furthermore, the organic halide is formamidine iodide, formamidine bromide, formamidine chloride, methylamine iodide, methylamine bromide, or methylamine chloride.

[0041] Furthermore, the concentration of the organic halide solution is 0.5-1 mol / mL.

[0042] In order to improve the quality of perovskite thin films and the energy conversion efficiency of perovskite solar cells, the evaporation angle is preferably controlled to be 15°≤θ<45°.

[0043] It is worth noting that the formation of the perovskite layer is a top-down crystallization process. The cationic solution gradually penetrates from the surface to the bottom of the cesium bromide / lead iodide mixed layer. Therefore, sufficient crystallization time must be ensured to allow the cations to completely penetrate to the bottom and allow the perovskite to fully crystallize. The preferred crystallization time is 15 to 30 seconds.

[0044] The present invention also provides an application of the high-quality perovskite layer in a perovskite solar cell.

[0045] Furthermore, the perovskite solar cell is a perovskite single junction cell or a perovskite / silicon-based tandem cell.

[0046] Furthermore, the perovskite single-junction cell includes a substrate, a hole transport layer, a high-quality perovskite layer, an electron transport layer and a surface electrode stacked in sequence from bottom to top; wherein, in order to ensure the light absorption thickness and further increase the current density, the thickness of the high-quality perovskite layer is 300 to 500 nm.

[0047] Furthermore, the perovskite / silicon-based stacked cell includes a silicon base cell, a hole transport layer, a high-quality perovskite layer, an interface passivation layer, an electron transport layer, a buffer layer, a window layer, a surface electrode and an anti-reflection layer stacked in sequence from bottom to top; wherein, in order to ensure the light absorption thickness and further increase the current density, the thickness of the high-quality perovskite layer is 600 to 700 nm, and the thickness of the inorganic layer is 400 to 500 nm.

[0048] In order to facilitate the transport of electrons, the material of the electron transport layer is a wide bandgap semiconductor (for example, titanium dioxide, tin oxide or zinc oxide) or fullerene and its derivatives (C 60 , PCBM). The electron transport layer may include a plurality of stacked transport sublayers, and the total thickness of the electron transport layer is 30 to 40 nm.

[0049] In order to prevent the window layer from being damaged during sputtering, the buffer layer is tin dioxide deposited by atomic layer deposition, and the total thickness of the buffer layer is 10-20 nm.

[0050] In order to effectively transmit light and promote electron transport, the window layer is a transparent conductive layer, for example, an indium tin oxide layer, an indium zinc oxide layer, an aluminum-doped zinc oxide layer or a boron-doped zinc oxide layer, and the thickness of the window layer is 40 to 80 nm.

[0051] In order to enhance the electron extraction capability, a layer of patterned silver is deposited on the top of the battery as a surface electrode. The thickness of the silver layer is 600 to 800 nm.

[0052] In order to reduce the degree of reflection of sunlight on the top surface of the stacked solar cell, an anti-reflection layer, such as lithium fluoride or magnesium fluoride, is added to the top surface. The thickness of the anti-reflection layer is 80-100 nm.

[0053] Example 1

[0054] This embodiment prepares a perovskite single junction cell with a structure as Figure 3 As shown, Figure 3 In the figure, 1 represents a glass substrate, 2 represents ITO (indium tin oxide), 3 represents a hole transport layer, 4 represents a perovskite layer, 5 represents an electron transport layer, and 6 represents a silver electrode.

[0055] The specific steps include:

[0056] Step 1: Pretreatment of ITO glass

[0057] The cut 1.5 cm×1.5 cm ITO glass (thickness 1.1 mm) was ultrasonically treated in acetone and anhydrous ethanol for 15 min respectively. After the ultrasonication, the glass was blown dry with a nitrogen gun, and then the ITO glass was placed in ozone for 15 min.

[0058] Step 2: Preparation of hole transport layer

[0059] Place the ITO glass obtained in step 1 into the mask for sputtering NiOx, place the mask into the magnetron sputtering equipment, and evacuate to 9×10 -4 Below Pa, select the RF magnetron sputtering mode, adjust the power to 90W, set the argon flow rate to 20sccm, and sputter for 10 minutes; after sputtering, transfer the glass sheet to a nitrogen glove box and place it on a spin coater to spin coat 2PACz, wherein the amount of 2PACz used during spin coating is 50μL, the rotation speed is 3000rpm, the acceleration is 3000rpm / s, and the duration is 30s, and then it is annealed at 110°C for 10 minutes to obtain a "glass / ITO layer / hole transport layer" structure.

[0060] Step 3: Evaporation of the inorganic layer

[0061] Place the wafer containing the "glass / ITO layer / hole transport layer" structure obtained in step 2 into a vacuum evaporation device, specifically place it on the surface of the substrate, and evacuate to 7×10 -4 Below Pa, the angle between the substrate and its normal (the direction perpendicular to the substrate) is adjusted to θ, the evaporation rate of CsBr is adjusted to 1 / 10 of the evaporation rate of PbI2, the total rate is 1.2 angstroms / second, and the total thickness is 200nm; after the evaporation is completed, a "glass / ITO layer / hole transport layer / inorganic layer" structure is obtained.

[0062] Step 4: Preparation of perovskite layer

[0063] Weigh 77.5 mg of FAI, 5.7 mg of MACl, and 12.6 mg of MABr and dissolve them in anhydrous ethanol. Shake for one hour to prepare a 1.5 M organic halide cation solution for later use.

[0064] The wafer with the structure of "glass / ITO layer / hole transport layer / inorganic layer" was placed on a spin coater, 70 μL of the organic halide cation solution prepared above was added dropwise, the rotation speed was adjusted to 3000 rpm, the acceleration was adjusted to 3000 rpm / s, and the spin coating was continued for 30 s to obtain a wafer with the structure of "glass / ITO layer / hole transport layer / inorganic layer / cation";

[0065] The obtained wafer was placed in an environment with an ambient humidity of 50% and annealed at 150° C. for 30 min to obtain a wafer with a structure of “glass / ITO layer / hole transport layer / perovskite layer”, wherein the thickness of the perovskite layer was 350 nm.

[0066] Step 5: Preparation of electron transport layer

[0067] Place the wafer with the structure of "glass / ITO layer / hole transport layer / perovskite layer" obtained in step 4 in a vacuum deposition mask, and place the mask in a vacuum deposition device and evacuate to 7×10 -4 Pa below, evaporation of LiF, C 60 layer and BCP layer at a rate of 1.0 angstrom / s with thicknesses of 1 nm, 100 nm and 1.5 nm, respectively, to obtain a sheet with a structure of “glass / ITO layer / hole transport layer / perovskite layer / electron transport layer”.

[0068] Step 6: Preparation of Silver Electrode

[0069] Place the wafer obtained in step 5 into the silver-evaporated mask, and then place the mask into a vacuum deposition device and evacuate to 7×10 -4 Pa, a 120nm thick silver electrode was evaporated to obtain a sheet with the structure of "glass / ITO layer / hole transport layer / perovskite layer / electron transport layer / silver electrode", that is, a perovskite single junction battery.

[0070] In this embodiment, the angle θ between the substrate and the normal phase during the evaporation process of the inorganic layer is adjusted to 15°, 30° and 45° respectively, so as to obtain the perovskite layer of the inorganic layer prepared based on different evaporation angles.

[0071] Example 2

[0072] This embodiment prepares a perovskite single-junction cell. Compared with Embodiment 1, the only difference is that in step 3, the angle θ between the substrate and the normal phase is limited to 45°, and in step 4, the preparation process of the perovskite layer is adjusted.

[0073] Specifically, the wafer with the structure of "glass / ITO layer / hole transport layer / inorganic layer" obtained in step 3 was transferred to another vacuum evaporation device, 75 mg of FAI was weighed and placed in an organic evaporation source, and the vacuum was evacuated to 7×10 -4 Pa, heat the organic evaporation source to 180°C, the evaporation rate is 3 angstroms / second, the thickness is 400nm, and a sheet with a "glass / ITO layer / hole transport layer / inorganic layer / FAI" structure is obtained; the above-obtained sheet is placed in an environment with an ambient humidity of 50%, and annealed at 150°C for 30 minutes to obtain a sheet with a "glass / ITO layer / hole transport layer / perovskite layer" structure, wherein the thickness of the perovskite layer is 450nm.

[0074] The other preparation processes and structures are the same.

[0075] Example 3

[0076] This embodiment prepares a perovskite / silicon-based stacked cell with a structure such as Figure 4 As shown, Figure 4Among them, 3 represents the hole transport layer, 4 represents the perovskite layer, 5 represents the electron transport layer, 7 represents the crystalline silicon cell, 8 represents the buffer layer, 9 represents the window layer, 10 represents the anti-reflection layer, and 11 represents the electrode.

[0077] The specific steps include:

[0078] Step 1: Preparation of silicon bottom cell

[0079] A silicon bottom battery with a pyramid velvet surface is used, and the undulation angle of the velvet surface is 53° (i.e. the angle between the undulating slope and the plane normal). The 15cm×15cm silicon bottom battery is cut into 2cm×2cm small batteries, and a patterned 1.2cm×1.2cm ITO composite layer is formed in the center of each small battery. The cutting accuracy deviation is controlled so that the size difference of each patterned composite layer is maintained within 1mm. The cut silicon bottom battery chips are annealed at 200℃ for 15min to obtain a "silicon bottom battery / composite layer" structure, wherein the thickness of the silicon bottom battery is 3μm and the thickness of the composite layer is 10nm.

[0080] Step 2: Preparation of hole transport layer

[0081] Place the "silicon bottom battery / composite layer" structure obtained in step 1 into the mask for sputtering NiOx, place the mask into the magnetron sputtering equipment, and evacuate to 9×10 -4 Below Pa, select the RF magnetron sputtering mode, adjust the power to 90W, set the argon flow rate to 20sccm, and sputter for 10 minutes; after sputtering, transfer the glass sheet to a nitrogen glove box and place it on a spin coater to spin coat 2PACz, wherein the amount of 2PACz used during spin coating is 50μL, the rotation speed is 3000rpm, the acceleration is 3000rpm / s, and the duration is 30s, and then it is annealed at 110°C for 10 minutes to obtain a "silicon bottom battery / composite layer / hole transport layer" structure.

[0082] Step 3: Evaporation of the inorganic layer

[0083] Place the wafer containing the structure of "silicon bottom cell / composite layer / hole transport layer" obtained in step 2 in the mask for evaporating PbI2, put the mask into the vacuum evaporation equipment, and evacuate to 7×10 -4 Pa or less; adjust the rate of CsBr to 1 / 10 of the rate of PbI2, and the total thickness of the inorganic layer is 400nm; after the evaporation is completed, a structure of "silicon bottom battery / composite layer / hole transport layer / inorganic layer" is obtained.

[0084] Step 4: Preparation of perovskite layer

[0085] Weigh 77.5 mg of FAI, 15.7 mg of MAC, and 12.6 mg of MABr and dissolve them in anhydrous ethanol. Shake for one hour to prepare a 1.7 M organic halide cation solution for later use.

[0086] The wafer with the structure of "silicon bottom battery / composite layer / hole transport layer / inorganic layer" is placed on a spin coater, 100 μL of the prepared organic halide cation solution is added dropwise, the rotation speed is adjusted to 4000 rpm and the acceleration is adjusted to 3000 rpm / s, and the spin coating is continued for 30 seconds to obtain a wafer with the structure of "silicon bottom battery / composite layer / hole transport layer / inorganic layer / cation";

[0087] The obtained wafer was placed in an environment with an ambient humidity of 50% and annealed at 170° C. for 30 minutes to obtain a wafer with a structure of “silicon bottom cell / composite layer / hole transport layer / perovskite layer”, wherein the thickness of the perovskite layer was 700 nm.

[0088] Step 5: Preparation of electron transport layer

[0089] Place the wafer with the structure of "silicon bottom cell / composite layer / hole transport layer / perovskite layer" obtained in step 4 in a vacuum deposition mask, and place the mask in a vacuum deposition device and evacuate to 7×10 -4 Pa below, LiF and C are evaporated 60 The layers are formed at a rate of about 0.1 angstroms / second with thicknesses of 1 nm and 10 nm respectively, obtaining a sheet with a structure of "silicon bottom battery / composite layer / hole transport layer / perovskite layer / electron transport layer".

[0090] Step 6: Preparation of buffer layer

[0091] Place the wafer with the structure of "silicon bottom battery / composite layer / hole transport layer / perovskite layer / electron transport layer" obtained in step 5 in the atomic layer deposition chamber, evacuate the chamber, set the chamber temperature not exceeding 200°C, set the water source and tin source pressures to 44Pa and 26Pa respectively, and cycle 100 times to obtain a wafer with the structure of "silicon bottom battery / composite layer / hole transport layer / perovskite layer / electron transport layer / buffer layer".

[0092] Step 7: Preparation of window ITO layer

[0093] The wafer with the structure of "silicon bottom cell / composite layer / hole transport layer / perovskite layer / electron transport layer / buffer layer" obtained in step 6 was placed in a patterned mask (1.1 cm × 1.1 cm square), and then the mask was placed in a magnetron sputtering instrument, and the substrate temperature was set to 60 °C, and the pressure in the chamber was 7 × 10 -4Start evaporation below Pa, control the argon flow rate to 20sccm, and the oxygen flow rate to 0.3sccm; use DC magnetron sputtering mode, sputter at 40W for 6 minutes and 30 seconds, then sputter at 150W for 4 minutes, to obtain a wafer with a structure of "silicon bottom battery / composite layer / hole transport layer / perovskite layer / electron transport layer / window ITO layer".

[0094] Step 8: Preparation of positive and back electrodes

[0095] Place the wafer with the structure of "silicon bottom cell / composite layer / hole transport layer / perovskite layer / electron transport layer / window ITO layer" obtained in step 7 into the mask of the positive electrode and the back electrode, and then place the mask into the vacuum deposition equipment and evacuate to 7×10 -4 Below Pa, a 600nm thick positive electrode and a 200nm thick back electrode were evaporated to obtain a sheet with the structure of "back electrode / silicon bottom battery / composite layer / hole transport layer / perovskite layer / electron transport layer / window ITO layer / positive electrode".

[0096] Step 9: Preparation of anti-reflection layer

[0097] Place the wafer with the structure of "back electrode / silicon bottom cell / composite layer / hole transport layer / perovskite layer / electron transport layer / window ITO layer / positive electrode" obtained in step 8 on a mask with a 1.1 cm × 1.1 cm hollow center, and then place the mask in a vacuum deposition device and evacuate to 10 -4 Pa, LiF is evaporated to form an anti-reflection layer with a thickness of 100nm to obtain a perovskite / silicon-based stacked cell.

[0098] Example 4

[0099] This embodiment prepares a perovskite single-junction cell. Compared with Embodiment 1, the only difference is that the evaporation process of the inorganic layer in Step 3 is adjusted.

[0100] Specifically, the wafer containing the "glass / ITO layer / hole transport layer" structure obtained in step 2 is placed in a vacuum evaporation device and evacuated to 7×10 -4 Pa or less; taking the direction of the connecting line between the CsBr evaporation source plane and the center of the substrate as the CsBr normal, adjusting the angle between the CsBr evaporation source plane and the CsBr normal to 45°; taking the direction of the connecting line between the PbI2 evaporation source plane and the center of the substrate as the PbI2 normal, adjusting the angle between the PbI2 evaporation source plane and the PbI2 normal to 45°; adjusting the CsBr evaporation rate to 1 / 10 of the PbI2 evaporation rate, the total rate to 1.2 to 2.0 angstroms per second, and the total thickness to 200 nm, and obtaining a "glass / ITO layer / hole transport layer / inorganic layer" structure after the evaporation is completed.

[0101] The other preparation processes and structures are the same.

[0102] Comparative Example 1

[0103] In this comparative example, a perovskite single-junction battery is prepared. Compared with Example 1, the only difference is that in step 3, the angle between the substrate and its normal is kept at 0°, that is, the evaporation angle is 0°; the other preparation processes and structures are the same.

[0104] Comparative Example 2

[0105] In this comparative example, a perovskite single-junction battery is prepared. Compared with Example 2, the only difference is that in step 3, the angle between the substrate and its normal is kept at 0°, that is, the evaporation angle is 0°; the other preparation processes and structures are the same.

[0106] Comparative Example 3

[0107] In this comparative example, a perovskite / silicon-based laminated cell is prepared. Compared with Example 3, the only difference is that the undulation angle of the substrate surface morphology is 0°, that is, a flat substrate is used; the other preparation processes and structures are the same.

[0108] The materials and devices obtained in Examples 1 to 4 and Comparative Examples 1 to 3 are characterized and their performances are tested below.

[0109] Figure 1 The SEM images of the inorganic layers obtained in Example 1 and Comparative Example 1 are shown in FIG. Figure 1 (a) is a SEM image of the surface of the inorganic layer of Example 1, Figure 1 (b) SEM image of the inorganic layer cross section of Example 1, Figure 1 (c) is the SEM image of the inorganic layer surface of Comparative Example 1, Figure 1 (d) SEM image of the cross section of the inorganic layer of Comparative Example 1. It can be seen that the columnar morphology of the inorganic layer can be achieved by adjusting the evaporation angle of the substrate.

[0110] Figure 2 Schematic diagram of residual stress distribution of the perovskite layer obtained in Example 1 and Comparative Example 1. It can be seen that by controlling the evaporation angle of the inorganic layer, compared with the traditional unadjusted evaporation angle of 0°, the obtained perovskite layer presents a consistent lattice spacing in the film, corresponding to a lower residual stress distribution, indicating that controlling the evaporation angle of the inorganic layer is beneficial to alleviating the residual stress caused by orientation disorder during the film growth process.

[0111] XRD tests were performed on the perovskite layer of the inorganic layer prepared at different evaporation angles obtained in Example 1 and the perovskite layer of the inorganic layer prepared at an evaporation angle of 0° obtained in Comparative Example 1. The results are as follows: Figure 5As shown, it can be seen that by adjusting the size of the angle θ, the crystallization properties of the perovskite layer can be controlled. The crystallinity is optimal at 45°, and there is basically no diffraction peak of PbI2, indicating that the reaction between the inorganic skeleton and the organic salt is sufficient, and there is basically no residual unreacted PbI2 at the bottom.

[0112] The perovskite single-junction solar cells provided in Example 1, Comparative Example 1, Example 2, and Comparative Example 2, as well as the perovskite / silicon-based tandem solar cells provided in Example 3 and Comparative Example 3, were tested for device performance. The performance of the perovskite single-junction solar cells was tested under standard test conditions (AM1.5G, 25°C, 1000W / m 2 ), the short-circuit current density (Jsc), the open-circuit voltage (Voc), the conversion efficiency (Eff) and the fill factor (FF) were measured under the conditions of 45° evaporation angle. The performance data are shown in Table 1, wherein the data of Example 1 is based on the evaporation angle of 45°; and the perovskite single-junction solar cells provided in Example 1 and Comparative Example 1 are taken as examples to obtain the following: Figure 6 Performance box plot shown, where Figure 6 (a) is the open circuit voltage, Figure 6 (b) is the short-circuit current density, Figure 6 (c) is the filling factor, Figure 6 (d) is the photoelectric conversion efficiency. It can be seen that whether by adjusting the evaporation source angle or the undulating angle of the substrate surface morphology, when the inorganic layer evaporation angle is controlled to 45°, compared with the traditional unadjusted 0° evaporation angle, the open circuit voltage, short circuit current, fill factor and battery efficiency are all improved to a certain extent.

[0113] Table 1

[0114]

[0115] Figure 7 JV diagrams of perovskite single junction solar cells provided for Example 1 and Comparative Example 1, Figure 8 JV diagrams of perovskite single junction solar cells provided for Example 2 and Comparative Example 2, Fig. 9 The JV diagrams of the perovskite / silicon-based tandem solar cells provided for Example 3 and Comparative Example 3 also prove that by controlling the evaporation angle of the inorganic layer, the diffusion of the organic halide cations in the second step can be made more uniform, and the open circuit voltage, short circuit current and fill factor of the devices prepared therefrom are significantly improved.

[0116] Fig.10 The EQE diagram of the perovskite / silicon-based tandem solar cell provided in Example 3 further proves that Fig. 9 Reliability of JV test results.

[0117] Fig.11 The SEM images of the inorganic layers obtained in Example 3 and Comparative Example 3 are shown in FIG. Fig.11(a) is a cross-sectional SEM image of the inorganic layer of Example 3, Fig.11 (b) SEM image of the cross section of the inorganic layer of Comparative Example 3. It can be seen that by using a substrate with a surface morphology with an undulation angle of 53°, the deposited inorganic layer can have a columnar morphology, while the inorganic layer deposited by using a substrate with a flat morphology is still a dense film, indicating that the regulation of the undulation angle of the substrate morphology can achieve the regulation of the columnar morphology of the inorganic layer.

[0118] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the text of the claims, or if they include equivalent structural elements that are not substantially different from the text of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a high-quality perovskite layer, characterized in that: The following steps are involved: Step 1, placing a substrate on a substrate surface, and preparing an inorganic layer on the substrate surface by evaporation; during the evaporation process, the evaporation source angle, the substrate angle, and / or the undulating angle of the substrate surface morphology are adjusted to control the evaporation angle to be 15°≤θ<60°, so as to obtain an inorganic layer with a nano-column morphology with controllable growth direction and adjustable column spacing; Step 2: thermally evaporate an organic halide or spin-coat an organic halide solution on the surface of the inorganic layer, and obtain a high-quality perovskite layer through annealing.

2. The method for preparing a high-quality perovskite layer according to claim 1, characterized in that: The material of the inorganic layer is at least one of lead iodide, lead bromide, lead chloride, cesium bromide, cesium iodide, cesium chloride, and cesium fluoride.

3. The method for preparing a high-quality perovskite layer according to claim 1, characterized in that: The organic halide is formamidine iodide, formamidine bromide, formamidine chloride, methylamine iodide, methylamine bromide or methylamine chloride.

4. The method for preparing a high-quality perovskite layer according to claim 3, characterized in that: The concentration of the organic halide solution is 0.5-1 mol / mL.

5. The method for preparing a high-quality perovskite layer according to claim 1, characterized in that: In step 2, the annealing temperature is 100-170° C., the duration is 15-30 minutes, and the humidity of the annealing environment is 30%-70%.

6. Use of the high-quality perovskite layer obtained by the preparation method according to any one of claims 1 to 5 in perovskite solar cells.

7. A perovskite single junction cell, characterized in that: It comprises a substrate, a hole transport layer, a high-quality perovskite layer obtained by the preparation method according to any one of claims 1 to 5, an electron transport layer and a surface electrode stacked in sequence from bottom to top; wherein the thickness of the high-quality perovskite layer is 300 to 500 nm.

8. A perovskite / silicon-based tandem battery, characterized in that: It comprises a silicon substrate battery, a hole transport layer, a high-quality perovskite layer obtained by the preparation method according to any one of claims 1 to 5, an interface passivation layer, an electron transport layer, a buffer layer, a window layer, a surface electrode and an anti-reflection layer stacked in sequence from bottom to top; wherein the thickness of the high-quality perovskite layer is 600 to 700 nm.

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