A method for preparing a perovskite light-absorbing layer by a pseudo screen printing process

Abstract

The present application belongs to the field of perovskite solar cell preparation, and relates to a method for preparing a perovskite light-absorbing layer by a pseudo screen printing process. In order to solve the problem of uniformly permeating perovskite ink in a large area at low cost on a porous framework layer, the present application provides a method for preparing a perovskite light-absorbing layer by a pseudo screen printing process, which comprises: (1) spreading perovskite ink onto a screen to form a liquid film on the screen by using the surface tension of the perovskite ink and the adhesion between the screen mesh wall and the perovskite ink; (2) lowering the liquid film from the mesh hole to form a liquid bridge between the liquid film and the printing substrate by extruding the screen, and absorbing and permeating into the printing substrate under the action of capillary force, and then obtaining a perovskite light-absorbing layer through crystallization treatment; the surface of the printing substrate is a porous layer. The method has the characteristics of compatibility with traditional screen printing equipment, high uniformity of large-area film formation, simplicity and easy enlargement, and low cost.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell fabrication and relates to a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process. Background Technology

[0002] The perovskite light-absorbing layer is the core of a perovskite solar cell. The quality of the film formation determines the product performance, directly affecting its carrier transport and photoelectric conversion performance. The fabrication process has a significant impact on cell performance. Low-cost, rapid fabrication of high-quality, large-area perovskite thin films is a crucial problem that must be solved to achieve the industrialization of perovskite solar cells.

[0003] Using a porous framework layer as a printing substrate, transferring a perovskite liquid film onto it, and then subjecting it to low-temperature crystallization to obtain perovskite solar cells is an important method for low-cost, large-area perovskite solar cell fabrication. These porous framework layers are typically fabricated on a transparent conductive substrate using screen printing to prepare multiple film layers, usually in the following order: a dense layer, a mesoporous electron transport layer, a mesoporous insulating layer, a mesoporous hole transport layer, and a mesoporous carbon electrode layer. Because these key film layers can be fabricated using a single screen printing machine, the fabrication process for perovskite solar cells becomes very simple and efficient. However, this process currently cannot achieve screen printing coating of the perovskite precursor solution, hindering process and equipment compatibility. Currently, the perovskite precursor solution is mainly penetrated into the porous framework layer via drop coating, which poses a significant obstacle to process compatibility. Furthermore, drop coating is not suitable for large-area cell fabrication, as it is impossible to simultaneously drop-coat the entire cell surface with the perovskite precursor solution manually. For example, when manufacturing a 600mm x 600mm battery, the time interval between adding the first and last drop of ink can be more than half an hour. During this period, uneven penetration of the perovskite solution can easily occur, affecting the filling effect. On the other hand, the perovskite precursor solution penetrated by the drop coating method results in poor uniformity of perovskite penetration after crystallization. A significant color difference can be observed between the droplet's landing location and the surrounding diffusion area. Furthermore, testing reveals a significant difference in battery power generation performance between the droplet's landing location and the diffusion area. Scaling up the drop coating process requires high-precision inkjet printing equipment; however, high-precision inkjet printing equipment requires high-precision inkjet head processing and is expensive. To improve the uniformity problem of forming large-area thin films by filling porous pores using the drop coating method, Chinese Patent Document 1 (Publication No. CN111048667A) invented a method of setting an auxiliary outer frame around the edges of the top electrode and in the interval area between adjacent top electrodes. The auxiliary frame method is effective for the permeation of perovskite precursor solution into porous framework layers, but it requires an additional auxiliary frame as a fixture. Therefore, how to achieve uniform permeation of perovskite precursor solution over a large area on a porous framework layer at low cost has become an urgent problem to be solved in the industrialization of perovskite solar cells. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a pseudo-screen printing process on a porous layer as a printing substrate to achieve liquid film transfer of perovskite ink. It features compatibility with traditional screen printing equipment, high uniformity of large-area film formation, simplicity and easy scaling, and low cost.

[0005] Specifically, the present invention provides a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process, comprising:

[0006] (1) The perovskite ink is spread onto the screen, and a liquid film is formed on the screen by utilizing the surface tension of the perovskite ink and the adhesion between the mesh wall of the screen and the perovskite ink.

[0007] (2) By extruding the screen, the liquid film descends from the mesh and forms a liquid bridge between it and the printing substrate. Under the action of capillary force, it penetrates into the printing substrate and is then crystallized to obtain a perovskite light-absorbing layer. The surface of the printing substrate is a porous layer.

[0008] Preferably, the wire mesh includes: a central mesh area and a non-porous area surrounding the central mesh area; the mesh size of the central mesh area is 18 to 250 micrometers.

[0009] The wire mesh is made of at least one of a metal material and a polymer material; the metal material includes stainless steel or tungsten; the polymer material is polyester.

[0010] In this invention, perovskite ink is dropped onto a non-porous area of ​​a screen, and a squeegee is used to spread the ink from one side of the screen to the other. During the ink spreading process, due to surface tension, the ink penetrates into the mesh openings of the screen. The adhesion between the ink and the mesh walls prevents leakage. The squeegee is then pressed firmly against the screen and moved from one side to the other, applying downward pressure to compress the liquid film within the mesh openings, causing it to descend and form a liquid bridge between the upper surface of the printing substrate and the lower surface of the screen mesh openings. Under capillary action, the perovskite ink penetrates into the printing substrate (porous layer or porous framework layer), and after crystallization, forms a perovskite light-absorbing layer.

[0011] According to the present invention, when perovskite ink is spread through the mesh of a screen using a doctor blade, the ink penetrates into the mesh due to surface tension during the liquid film formation process. Simultaneously, due to the adhesion between the mesh wall and the ink, the ink dispersed within each mesh remains within the mesh and does not leak. This invention ensures a match between the surface tension of the perovskite ink, its adhesion to the mesh wall, and the mesh size. If the adhesion between the ink and the mesh wall is too weak, the ink may not be able to hold the liquid within the mesh and may leak directly. Alternatively, if too much ink is spread within the same mesh, the ink's gravity may exceed the vertical upward component of its adhesion to the mesh wall, also resulting in direct leakage. Compared to commonly used methods, this method has advantages such as compatibility with traditional screen printing equipment, high film uniformity, simplicity and ease of scaling up, and low cost.

[0012] Preferably, the chemical composition of the perovskite material in the perovskite ink is ABX3, where A is a monovalent cation and A is [CH(NH2)2]. + [NH3NH2]+ [(CH2)3NH2] + [NH3OH] + [C3N2H5] + [(CH3CH2)NH3] + [(CH3)2NH2] + [(NH2)3C] + [(CH3)4N] + [C3H4NS] + [NC4H8] + [C7H7] + K + 、Rb + Cs + At least one of them; B is Pb 2+ Sn 2 + Co 2+ Mn 2+ 、Ge 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Cu 2+ Fe 2+ Pd 2+ Eu 2+ Ni 2+ and Bi 3+ At least one of them; X is F - Cl - ,Br - I - and SCN - At least one of them;

[0013] The solvent of the perovskite ink is selected from at least one of dimethylformamide, N-methylformamide, dimethyl sulfoxide, γ-valerolactone, γ-butyrolactone, N-methyl-2-pyrrolidone methanol, isopropanol, ethylene glycol, water, ethyl acetate, triethyl phosphate, 2-methoxyethanol, cyclopentyl methyl ether, and N-hydroxymethylacrylamide.

[0014] The concentration of the perovskite ink is 0.5–2.0 mol / L;

[0015] The surface tension coefficient of the perovskite ink is >5 mN / m. The perovskite ink includes, but is not limited to, perovskite solutions, perovskite colloidal dispersions, and perovskite turbid solutions.

[0016] Preferably, the printing substrate includes: a substrate, a transparent conductive layer, a dense layer, an electron transport layer, an insulating layer, a hole transport layer, and a top electrode layer, with the top electrode side facing the screen and placed parallel to it; wherein the electron transport layer, the insulating layer, the hole transport layer, and the top electrode layer all have a porous structure.

[0017] Furthermore, preferably, the substrate is made of at least one of metallic materials, inorganic non-metallic materials, and polymeric materials; the thickness of the substrate is 0.001 to 5 mm.

[0018] The transparent conductive layer is made of materials including indium tin oxide, zinc aluminum oxide, indium zinc oxide, fluorine-doped tin oxide, graphene and its derivatives; the thickness of the transparent conductive layer is 2-300 nanometers.

[0019] The dense layer is made of metal oxide; the thickness of the dense layer is 2–100 nanometers.

[0020] The electron transport layer is made of at least one of the following materials: titanium oxide and its dopants, tin oxide and its dopants, indium oxide and its dopants, zinc oxide and its dopants, cadmium sulfide and its dopants, zinc sulfide and its dopants, zinc selenide and its dopants, fullerene and its derivatives, graphene and its derivatives, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)methylborane; the thickness of the electron transport layer is 0.002–2 micrometers.

[0021] The insulating layer is made of at least one of aluminum oxide, zirconium oxide, and magnesium oxide; the thickness of the insulating layer is 0.1 to 4 micrometers.

[0022] The hole transport layer is made of at least one of the following materials: copper oxide, copper iodide, copper sulfide, cuprous thiocyanate, copper antimony sulfide, tungsten oxide, nickel oxide, molybdenum oxide, cerium oxide, vanadium oxide, manganese oxide, cobalt oxide, tungsten sulfide, and molybdenum sulfide; the thickness of the hole transport layer is 0.05 to 20 micrometers.

[0023] The material of the top electrode layer includes at least one of graphite, carbon black, carbon nanotubes, carbon fiber, and graphene; the thickness of the top electrode layer is 1 to 200 micrometers.

[0024] Furthermore, preferably, the metal oxide includes at least one of titanium oxide and its dopants, tin oxide and its dopants, and zinc oxide and its dopants.

[0025] Preferably, the electron transport layer has a pore size of 5–100 nanometers and a porosity of 10–80%.

[0026] The insulating layer has a pore size of 0.001 to 1 micrometer and a porosity of 10 to 80%.

[0027] The hole transport layer has a pore size of 0.001–1 micrometer and a porosity of 10–80%.

[0028] The top electrode layer has a pore size of 0.001–6.5 micrometers and a porosity of 10–90%.

[0029] Preferably, the distance between the screen and the printing substrate is 0 to 3 millimeters.

[0030] Preferably, the perovskite ink is spread onto the screen using a doctor blade; the parameters of the doctor blade include: a moving speed of 0 to 300 mm / s and not 0, a gap between the doctor blade and the screen being 0 to 0.5 mm, an angle between the doctor blade and the screen being >0 degrees and <180 degrees, and a pressure of 0 Pa between the doctor blade and the screen being 0 Pa.

[0031] The perovskite ink is dropped onto a non-porous area on one side of the screen, and then spread from the non-porous area on one side of the screen to the non-porous area on the other side of the screen using a doctor blade.

[0032] Preferably, the ink is applied to the screen by pressing with a doctor blade. The doctor blade parameters include: a downward pressure of 0.01–0.6 MPa, a moving speed of 0–300 mm / s (not zero), and an angle between the doctor blade and the screen mesh of >0 degrees and <180 degrees. More preferably, when residual ink remains after the perovskite ink is applied to the screen mesh using the doctor blade, the doctor blade avoids or does not avoid the residual ink during the application process. The residual ink refers to the portion of ink remaining on the non-porous areas after the ink application is complete.

[0033] Preferably, the crystallization treatment is performed at a temperature of room temperature to 300 degrees Celsius for a time of 2 to 1440 minutes.

[0034] On the other hand, the present invention provides a perovskite light-absorbing layer prepared by a method for preparing a perovskite light-absorbing layer according to a pseudo screen printing process.

[0035] In another aspect, the present invention provides a perovskite solar cell, comprising: a perovskite light-absorbing layer prepared by a method for preparing a perovskite light-absorbing layer according to a pseudo-screen printing process.

[0036] The beneficial effects of this invention are:

[0037] This invention provides a method for fabricating a perovskite light-absorbing layer that is compatible with traditional screen printing equipment, exhibits high uniformity in large-area film formation on a printing substrate, is simple and easily scalable, and is low-cost. The above-described contents, objectives, features, and advantages of this invention will be better understood from the following detailed embodiments and with reference to the accompanying drawings. Attached Figure Description

[0038] Figure 1 This is a front view of a perovskite solar cell after the perovskite light-absorbing layer is formed, according to a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process based on the present invention.

[0039] Figure 2 This is a top view of the screen and squeegee in a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process according to the present invention.

[0040] Figure 3 This is a side view of the liquid spreading process in a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process according to the present invention.

[0041] Figure 4 This is a side view of the liquid-feeding process in a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process according to the present invention, without the current collection strip.

[0042] Figure 5 This is a comparison chart of the electroluminescence test performance of a battery with a perovskite light-absorbing layer prepared by using the method of Example 1 and Comparative Example 1 in a method for preparing a perovskite light-absorbing layer according to a pseudo-screen printing process of the present invention.

[0043] Figure 6 This is a comparison chart of the photoelectric conversion performance of a battery with a perovskite light-absorbing layer prepared using the method of Example 1 and Comparative Example 1 in a method for preparing a perovskite light-absorbing layer according to a pseudo-screen printing process of the present invention.

[0044] Figure 7 This is a comparison chart of the photoelectric conversion performance of a battery with a perovskite light-absorbing layer prepared using the methods of Examples 2 to 6 in a method for preparing a perovskite light-absorbing layer according to a pseudo-screen printing process of the present invention.

[0045] In the attached figure, the perovskite light-absorbing layer 8, the perovskite ink 8a, the liquid film 8b, and the residual liquid 8c represent different stages in the perovskite ink film formation process. Therefore, the same reference numerals are used in the figure, but different explanatory text will be used.

[0046] Although the top electrode layer in the attached diagram belongs to the printed substrate, additional annotations are used because the graphic size differs from that of the printed substrate.

[0047] The shapes of the perovskite ink and mesh in the attached diagram are for ease of distinction only and are not limited thereto;

[0048] The perovskite ink, liquid film, and residual liquid in the attached diagram are for illustrative purposes only and are not limited to these.

[0049] The front and rear views of the perovskite ink and the mesh walls in the attached diagram are for ease of distinction only and are not limited thereto.

[0050] Appendix Figure 4The diagram does not include a current collection bar, but this is not a limitation for ease of illustration.

[0051] Figure label:

[0052] 0. Printing substrate

[0053] 1. Substrate;

[0054] 2. Transparent conductive layer;

[0055] 3. Dense layer;

[0056] 4. Porous layer;

[0057] 5. Top electrode layer;

[0058] 6. Current collection bar;

[0059] 7. Insulation area;

[0060] 8. Perovskite light-absorbing layer;

[0061] 8a. Perovskite ink (hereinafter referred to as ink);

[0062] 8b. Liquid film;

[0063] 8c, residual liquid;

[0064] 10. Silk screen;

[0065] 10a. Mesh

[0066] 10b. Non-porous area

[0067] 12. Scraper. Detailed Implementation

[0068] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0069] In this disclosure, perovskite ink is spread onto a screen, and a liquid film is formed on the screen using the surface tension of the ink and the adhesion between the ink and the screen mesh walls, preventing leakage. The screen is then pressed by a squeegee, causing the liquid film to descend through the mesh openings and, under capillary action, penetrate into the printing substrate. The method comprises: a printing substrate containing a porous layer, perovskite ink with a certain surface tension, a screen with a certain pore size, and a squeegee. The porous layer sequentially includes an electron transport layer, an insulating layer, a hole transport layer, and a top electrode layer. Therefore, a method for fabricating a perovskite light-absorbing layer on a printing substrate, characterized by high uniformity over a large area, simplicity, easy scale-up, and low cost, is provided.

[0070] In an optional embodiment, the printed substrate comprises: a substrate, a transparent conductive layer, a dense layer, an electron transport layer, an insulating layer, a hole transport layer, and a top electrode layer, with the top electrode side facing the screen and placed parallel to it. Preferably, the substrate is selected from at least one of metallic materials, inorganic non-metallic materials, and polymeric materials, and has a thickness of 0.001–5 mm. Preferably, the transparent conductive layer is selected from indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), graphene, and its derivatives, and has a thickness of 2–300 nm. Preferably, the dense layer is made of metal oxides, preferably at least one of titanium oxide and its dopants, tin oxide and its dopants, and has a thickness of 2–100 nm. Preferably, the electron transport layer is selected from at least one of titanium oxide and its dopants, tin oxide and its dopants, indium oxide and its dopants, zinc oxide and its dopants, cadmium sulfide and its dopants, zinc sulfide and its dopants, zinc selenide and its dopants, fullerene and its derivatives, graphene and its derivatives, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), and tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)methylborane (3TPYMB), with a thickness of 0.002–2 micrometers, a pore size of 5–100 nanometers, and a porosity of 25–75%. Preferably, the insulating layer is selected from at least one of alumina, zirconium oxide, and magnesium oxide, with a thickness of 0.1–4 micrometers, a pore size of 0.001–1 micrometer, and a porosity of 25–75%. Preferably, the hole transport layer is selected from at least one of copper oxide, copper iodide, copper sulfide, cuprous thiocyanate, copper antimony sulfide, tungsten oxide, nickel oxide, molybdenum oxide, cerium oxide, vanadium oxide, manganese oxide, cobalt oxide, tungsten sulfide, and molybdenum sulfide, with a thickness of 0.05–20 micrometers, a pore size of 0.001–1 micrometer, and a porosity of 25–75%. Preferably, the top electrode layer is selected from at least one of graphite, carbon black, carbon nanotubes, carbon fibers, and graphene, with a thickness of 1–200 micrometers, a pore size of 0.001–6.5 micrometers, and a porosity of 15–90%.

[0071] In a more preferred embodiment, the dopant in the titanium oxide includes at least one of alkali (earth) metal elements, non-metal elements, and transition metal elements, with a total doping content not exceeding 10 mol%. Alkali (earth) metal elements include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, etc. Non-metal elements include nitrogen, carbon, sulfur, fluorine, chlorine, bromine, iodine, boron, phosphorus, silicon, etc. Transition metal elements include iron, cobalt, nickel, manganese, copper, zinc, cadmium, niobium, tantalum, aluminum, gallium, germanium, antimony, bismuth, indium, tin, vanadium, chromium, molybdenum, silver, platinum, etc.

[0072] In a more preferred embodiment, the dopant in the tin oxide includes at least one of alkali (earth) metal elements, non-metal elements, and transition metal elements, with a total doping content not exceeding 10 mol%. Alkali (earth) metal elements include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium. Non-metal elements include nitrogen, carbon, sulfur, fluorine, chlorine, bromine, iodine, boron, phosphorus, and silicon. Transition metal elements include titanium, iron, cobalt, nickel, manganese, copper, zinc, cadmium, niobium, tantalum, aluminum, gallium, germanium, antimony, bismuth, indium, vanadium, chromium, molybdenum, silver, and platinum.

[0073] In a more preferred embodiment, the dopant in the indium oxide includes at least one of alkali (earth) metal elements, non-metal elements, and transition metal elements, with a total doping content not exceeding 10 mol%. Alkali (earth) metal elements include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, etc. Non-metal elements include nitrogen, carbon, sulfur, fluorine, chlorine, bromine, iodine, boron, phosphorus, silicon, etc. Transition metal elements include titanium, iron, cobalt, nickel, manganese, copper, zinc, cadmium, niobium, tantalum, aluminum, gallium, germanium, antimony, bismuth, tin, vanadium, chromium, molybdenum, silver, platinum, etc.

[0074] In a more preferred embodiment, the dopant in the zinc oxide includes at least one of alkali (earth) metal elements, non-metal elements, and transition metal elements, with a total doping content not exceeding 10 mol%. Alkali (earth) metal elements include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium. Non-metal elements include nitrogen, carbon, sulfur, fluorine, chlorine, bromine, iodine, boron, phosphorus, and silicon. Transition metal elements include titanium, iron, cobalt, nickel, manganese, copper, cadmium, niobium, tantalum, aluminum, gallium, germanium, antimony, bismuth, indium, tin, vanadium, chromium, molybdenum, silver, and platinum.

[0075] In a more preferred embodiment, the dopant element in the cadmium sulfide dopant includes at least one of zinc, magnesium, calcium, strontium, barium, copper, silver, barium, gallium, thallium, aluminum, cobalt, nickel, manganese, germanium, tin, silicon, selenium, and tellurium, and the total dopant content does not exceed 10 moles.

[0076] In a more preferred embodiment, the dopant element in the zinc sulfide dopant includes at least one of cadmium, magnesium, calcium, strontium, barium, copper, silver, barium, gallium, thallium, aluminum, cobalt, nickel, manganese, germanium, tin, silicon, selenium, and tellurium, and the total dopant content does not exceed 10 moles.

[0077] In a more preferred embodiment, the dopant element in the zinc selenide dopant includes at least one of cadmium, magnesium, calcium, strontium, barium, copper, silver, barium, gallium, thallium, aluminum, cobalt, nickel, manganese, germanium, tin, silicon, sulfur, and tellurium, and the total dopant content does not exceed 10 moles.

[0078] In a more preferred embodiment, the fullerene derivatives include: methyl [6,6]-phenyl-carbon-61-butyrate, methyl [6,6]-phenyl-carbon-71-butyrate, fullerpyrrolidine, etc.

[0079] In a more preferred embodiment, the graphene derivatives include: chlorinated graphene, fluorinated graphene, graphene oxide, reduced graphene oxide, carboxylated graphene, aminated graphene, nitrogen-doped graphene, phosphorus-doped graphene, sulfur-doped graphene, boron-doped graphene, etc.

[0080] In an optional embodiment, to create a more uniform liquid film, the pore size of the screen mesh is preferably 18–250 micrometers. The perovskite ink with a certain surface tension can be a perovskite solution, a perovskite turbid liquid, a perovskite colloidal dispersion, etc.

[0081] In optional embodiments, the doctor blade must be made of a material compatible with the composition of the perovskite ink to prevent corrosion and ensure the ink's performance. Preferably, at least one of a metallic material, an inorganic non-metallic material, or a polymeric material is selected. In optional embodiments, the same doctor blade can be used for both spreading and pouring the ink, or two doctor blades made of different materials can be used for spreading and pouring the ink separately.

[0082] In an optional embodiment, during the liquid spreading process, the doctor blade spreads the ink from a non-porous area on one side of the screen to a non-porous area on the opposite side. As the ink spreads and forms a liquid film, surface tension causes it to penetrate into the mesh openings of the screen. Simultaneously, due to the adhesive force between the mesh walls and the ink, the ink dispersed into each mesh opening remains within the opening and does not leak out.

[0083] In an optional embodiment, the liquid spreading process of the squeegee is controlled by adjusting various parameters of the squeegee, including: moving speed, gap between the squeegee and the screen, angle between the squeegee and the screen, and squeegee material, to control the amount of liquid spread. This prevents the ink from leaking directly into the printing substrate due to its own weight exceeding the adhesion force between the screen wall and the ink during the ink film formation process. Preferably, the moving speed can be set to 0–300 mm / s and not 0; the gap between the squeegee and the screen can be set to 0–0.5 mm; the angle between the squeegee and the screen can be set to >0 degrees and <180 degrees (e.g., 15 degrees, 30 degrees, 45 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees, etc.); and the squeegee material can be at least one of metal, inorganic non-metallic, or polymer materials.

[0084] In an optional embodiment, the squeegee spreads the ink from a non-porous area on one side of the screen to a non-porous area on the opposite side. Alternatively, in this invention, the squeegee can press the screen, altering the adhesion between the perovskite ink remaining within the mesh openings and the mesh wall, thereby transferring it to the printing substrate.

[0085] In an optional embodiment, the liquid-feeding process of the scraper is controlled by adjusting various parameters, including: the downward pressure of the scraper, the moving speed, the angle between the scraper and the wire mesh, the scraper material, and the gap between the porous layer and the wire mesh, thereby controlling the liquid-feeding volume. Preferably, the downward pressure of the scraper can be set to 0.01–0.6 MPa, the moving speed can be set to 0–300 mm / s and is not zero, the angle between the scraper and the wire mesh can be set to >0 degrees and <180 degrees (e.g., 15 degrees, 30 degrees, 45 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees, etc.), the gap between the porous layer and the wire mesh can be set to 0–3 mm, and the scraper material can be a non-rigid polymer material, preferably silicone and fluoropolymer.

[0086] In this invention, the screen is elastic; the screen material must be compatible with the perovskite ink to avoid corrosion and affecting the performance of the perovskite ink. For example... Figure 2 As shown, the perimeter of the wire mesh 10 is a non-porous area 10b, where no liquid is allowed to flow; the center is a perforated area with holes 10a, where liquid can flow. Preferably, the wire mesh material can be stainless steel, polyester, or tungsten.

[0087] In this invention, the process of the perovskite ink penetrating into the printing substrate can be either simultaneous point and line penetration from line to surface during the movement of the squeegee, or the perovskite ink penetrating the entire surface under the action of capillary force formed between the upper surface of the printing substrate and the lower surface of the screen.

[0088] The following exemplarily illustrates a method for fabricating a perovskite light-absorbing layer, including:

[0089] 1) A dense layer and a porous layer (the porous layer includes an electron transport layer, an insulating layer, a hole transport layer, and a top electrode layer) are sequentially fabricated on a transparent conductive layer on a substrate as a printing substrate;

[0090] 2) Drop perovskite ink onto a non-porous area on one side of the screen;

[0091] 3) Use a squeegee to spread the ink from the non-porous area on one side of the screen to the non-porous area on the other side of the screen;

[0092] 4) During the ink spreading process, the surface tension of the perovskite ink and the adhesion between the mesh walls of the screen and the perovskite ink are used to form a liquid film on the screen, preventing leakage.

[0093] 5) Apply downward pressure to the squeegee to squeeze the liquid film in the mesh, change the adhesion between the ink penetrating inside the mesh and the mesh wall, cause the liquid film to fall from the mesh, and form a liquid bridge between the upper surface of the printing substrate and the lower surface of the screen mesh.

[0094] 6) Perovskite ink penetrates into the printing substrate under the action of capillary force;

[0095] 7) After crystallization, a high-quality perovskite light-absorbing layer is obtained.

[0096] In this invention, the core process of preparing a perovskite light-absorbing layer using the above-mentioned pseudo-screen printing process utilizes the surface tension of the ink itself: spreading to form a liquid film, penetrating into the mesh of the screen; adsorbing in the pores without leaking out; and penetrating into the printing substrate under the action of capillary force, thus resulting in higher film quality.

[0097] In this invention, the solvent for the perovskite ink may also need to have the characteristic of being non-volatile. This ensures that during mass production, the ink will not dry inside the mesh and cause clogging. Therefore, a solvent with a low saturated vapor pressure is preferably selected.

[0098] In this invention, the surface tension of the ink can be increased by adding non-surface-active substances, such as inorganic salts, non-volatile acids, and alkalis, or it can be decreased by adding surface-active substances, such as short-chain fatty acids, alcohols, and aldehydes.

[0099] In this invention, if the contact angle between the ink and the porous layer is too large (the wettability between the ink and the porous layer is poor), the wettability of the ink on the surface of the porous layer can be improved by ultraviolet treatment and / or plasma treatment.

[0100] Figure 1 This is a front view of a perovskite solar cell after the perovskite ink of one embodiment of the present invention has permeated into a porous layer. Figure 2 This is a top view of the wire mesh and scraper used in one embodiment of the present invention. Figure 3 This is an enlarged side view of the entire liquid-laying process, from the initial liquid-laying stage to the moment before liquid is poured. Figure 4 This is a magnified side view of the entire liquid discharge process, without a current collection bar. Figure 5 This is a comparison of the electroluminescence performance of solar cells with perovskite light-absorbing layers fabricated using the methods of Example 1 and Comparative Example 1. Figure 6 This is a comparison of the photoelectric conversion performance of solar cells with perovskite light-absorbing layers fabricated using the methods of Example 1 and Comparative Example 1. Figure 7This table compares the photoelectric conversion performance of batteries with perovskite light-absorbing layers fabricated using the methods described in Examples 2-6. Table 1 shows a comparison of the specific parameters of the batteries in the examples and comparative examples. To solve the above-mentioned technical problems, this invention provides a method for fabricating a high-quality perovskite light-absorbing layer on a printed substrate that exhibits high film uniformity, is simple and easily scaled up, and is low-cost.

[0101] Furthermore, this embodiment and subsequent embodiments will be described in detail, such as Figure 1 As shown: An insulating region 7, used to distinguish the positive and negative electrodes of the battery, is fabricated on the transparent conductive layer 2 of the substrate 1, making the transparent conductive layer 2 discontinuous; a dense layer 3, a porous layer 4, and a top electrode layer 5 are sequentially fabricated on the transparent conductive layer 2; the combination of the above 1-5 is defined as the printed substrate 0. The top electrode layer 5 is fabricated above the porous layer 4, spans the insulating region 7, and contacts the transparent conductive layer 2 to the right of the insulating region 7; a current collecting strip 6 is fabricated on the outermost edge of the transparent conductive layer 2, serving as the positive and negative electrodes of the battery.

[0102] use Figure 2 The wire mesh shown begins the liquid spreading process (as shown). Figure 3 (as shown) and the liquid discharge process (such as) Figure 4 (As shown).

[0103] like Figure 3 As shown, when the perovskite ink 8a is scraped through the mesh 10a of the screen 10 using the doctor blade 12, the perovskite ink 8a spreads onto the screen 10 during the scraping process due to surface tension, forming a liquid film 8b. This film does not leak due to adhesion to the mesh walls. Specifically, the liquid spreading process includes: applying the perovskite ink 8a to be penetrated to the non-porous area 10b of the screen 10; and using the doctor blade 12 to spread the perovskite ink 8a from one side of the non-porous area 10b to the opposite side of the screen 10. During the spreading process, the perovskite ink 8a spreads onto the screen 10 due to surface tension, forming a liquid film 8b. This film does not leak due to adhesion to the mesh walls.

[0104] like Figure 4 As shown, the liquid film 8b permeates into the mesh 10a of the wire mesh 10, and the remaining residual liquid 8c is scraped by the scraper 12 into the non-porous region 10b of the wire mesh 10. When the liquid is about to be released, the scraper 12 is held close to the wire mesh 10 and moved from one side of the non-porous region 10b to the opposite side of the wire mesh 10. During this process, downward pressure is applied to the scraper 12 to compress the wire mesh 10, changing the adhesion between the liquid inside the mesh 10a and the pore wall, causing the liquid film 8b to descend from the mesh 10a and form a liquid bridge between the upper surface of the porous layer 4 and the lower surface of the mesh 10a of the wire mesh 10. Under the action of capillary force, the liquid film 8b permeates into the porous layer 4. Furthermore, during the liquid release process, the scraper 12 may or may not avoid the residual liquid 8c.

[0105] Finally, a crystallization process is performed to form a perovskite light-absorbing layer. Preferably, the crystallization temperature can be room temperature to 300 degrees Celsius, and the time can be 2 to 1440 minutes.

[0106] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0107] Example 1: Fabrication of a perovskite light-absorbing layer using the method of the present invention.

[0108] 1) An insulating region is created on the FTO conductive layer on a glass substrate using laser etching, making the FTO conductive layer discontinuous. The two sides of the insulating region serve as the positive and negative electrode regions of the battery, respectively.

[0109] 2) Clean the FTO glass ultrasonically for 15 minutes each with acetone, alkaline detergent, deionized water, and acetone respectively, and then blow it dry.

[0110] 3) To prepare a TiO2 dense layer by screen printing on the FTO conductive layer, a screen printing paste containing the following components, namely 1.5 ml tetraisopropyl titanate, 3.5 g ethyl cellulose, and 80 ml terpineol, is printed and coated on the FTO conductive layer and sintered in a muffle furnace at 510 degrees Celsius for 30 minutes to form a TiO2 dense layer.

[0111] 4) On the dense layer, titanium dioxide paste (solid content mass fraction of 10%, solvent is terpineol) is screen printed, and sintered in a muffle furnace at 510 degrees Celsius for 30 minutes to form a porous electron transport layer.

[0112] 5) On the electron transport layer, a zirconium dioxide paste (solid content mass fraction of 5%, solvent of terpineol) is screen printed and sintered in a muffle furnace at 510 degrees Celsius for 30 minutes to form a porous insulating layer.

[0113] 6) On the insulating layer, a nickel oxide paste (solid content of 5% by mass, solvent of terpineol) is screen-printed and sintered in a muffle furnace at 510 degrees Celsius for 30 minutes to form a porous hole transport layer.

[0114] 7) On the hole transport layer, carbon paste (solid content 37% by mass, solvent terpineol) is screen-printed and sintered in a muffle furnace at 430 degrees Celsius for 30 minutes to form a porous top electrode. Layers 4) to 7) above are called the porous layers before perovskite infiltration;

[0115] 8) On the FTO conductive layer, attach tin-plated copper tape as a current collection strip;

[0116] 9) Weigh 15.3 mg of 5-aminovaleric hydroiodide (5-AVAI), 576 mg of lead iodide (PbI2), and 195 mg of methylamine iodide (CH3NH3I) powder. Measure 1 mL of a mixed solvent (gamma-valerol (GVL) and ethanol volume ratio = 4:1). Stir at 60°C for 6 hours to form CH3NH3PbI3 perovskite ink (concentration 1.25 mol / L, surface tension coefficient approximately 26 mN / m).

[0117] 10) Place the printing substrate on a horizontal platform;

[0118] 11) Use stainless steel wire to make a mesh screen with an outer frame size of 550 mm × 550 mm and a central mesh area size of 180 mm × 180 mm. The mesh count is 165 meshes (mesh size is 93 microns). Place the screen screen above the printing substrate and adjust the gap between the lower surface of the screen screen and the upper surface of the printing substrate to 0.4 mm.

[0119] 12) Add 1.0 ml of perovskite ink to a non-porous area on one side of the screen. After it spreads out, use a 250 mm long stainless steel squeegee to directly contact and apply no pressure to the screen to scrape the ink from the non-porous area on one side of the screen to the non-porous area on the other side at a uniform speed of 80 mm / s. The angle between the squeegee and the screen is 90 degrees, and the pressure between the squeegee and the screen is 0 Pa. At this point, the ink penetrates into the mesh and does not leak due to the adhesion force with the mesh wall.

[0120] 13) Using another 250 mm long silicone squeegee, directly contact the screen and apply a pressure of 0.24 MPa above it. Move the squeegee at a constant speed from one non-porous area of ​​the screen to the other, without avoiding residual liquid. Set the moving speed to 80 mm / s and the angle between the squeegee and the screen to 60 degrees. When passing through the perforated area, the adhesion between the liquid in the screen openings and the opening walls changes due to the squeegee's pressure on the screen, causing the liquid film to descend from the openings and form a liquid bridge between the upper surface of the carbon layer and the lower surface of the screen openings. Under the action of capillary force, the perovskite ink penetrates into the printing substrate;

[0121] 14) Let it stand for 20 minutes to allow it to fully penetrate, then crystallize at 50 degrees Celsius for 2 hours to produce a perovskite solar cell.

[0122] Example 2

[0123] Using the method of the present invention, a perovskite light-absorbing layer is prepared. The preparation method is the same as in Example 1, except that a 400-mesh screen (mesh size of 38 micrometers) is used.

[0124] Example 3

[0125] Using the method of the present invention, a perovskite light-absorbing layer is prepared. The preparation method is the same as in Example 1, except that the mesh size of the screen used is 100 mesh (the mesh size is 150 micrometers).

[0126] Example 4

[0127] Using the method of the present invention, a perovskite light-absorbing layer is prepared. The preparation method is the same as in Example 1, except that in step 13), when the liquid is poured, the pressure of the scraper is 0.35 MPa.

[0128] Example 5

[0129] Using the method of this invention, a perovskite light-absorbing layer is fabricated. The fabrication method is the same as in Example 1, except that an 80-mesh screen (180 micrometers mesh size) is used. In step 13), the pressure of the scraper used during liquid addition is 0.12 MPa.

[0130] Example 6

[0131] Using the method of the present invention, a perovskite light-absorbing layer is prepared. The preparation method is the same as in Example 1, except that in step 9), γ-butyrolactone (GBL) is used instead of γ-valerol (GVL), and the ratio remains unchanged (concentration is 1.25 mol / L, surface tension coefficient is about 33 mN / m); when adding the liquid, the scraper avoids the residual liquid.

[0132] Comparative Example 1: Fabrication of Perovskite Solar Cells

[0133] 1) Steps 1) to 9) are the same as in Example 1.

[0134] 2) A fixed amount of perovskite ink is precisely dropped onto the carbon layer using a series of pipettes. After standing for 20 minutes to allow it to fully penetrate and fill the carbon layer, the ink is crystallized at 50 degrees Celsius for 2 hours to produce a perovskite solar cell.

[0135] Figure 5 The diagram shows a comparison of the electroluminescence performance of perovskite solar cells fabricated using the method of the present invention and those fabricated using conventional processes. The perovskite solar cells fabricated using the method of the present invention exhibit superior electroluminescence uniformity compared to perovskite solar cells fabricated using conventional drop-addition methods.

[0136] Figure 6-7The diagram shows a comparison of the photoelectric conversion performance of perovskite solar cells fabricated using the method of the present invention and those fabricated using conventional processes. The perovskite solar cells fabricated using the method of the present invention exhibit superior photoelectric conversion performance compared to perovskite solar cells fabricated using the conventional drop-on method. (See Table 1 and...) Figure 6-7 It can be observed that the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF), and photoelectric conversion efficiency (Eff) of the battery produced by the method of the present invention are all higher than those of Comparative Example 1.

[0137] Table 1 compares the specific parameters of the batteries in the examples and comparative examples:

[0138] .

[0139] Of Examples 1-5, Example 1 exhibits the best performance because, under the premise of using the same perovskite ink and the same porous material (i.e., the ink concentration and surface tension coefficient are constant, and the porosity and pore size of the porous material are constant), adjusting the mesh size (i.e., pore size) and / or the pressure applied during liquid injection allows for the control of the optimal liquid injection amount. The liquid injection amount directly affects battery performance. Example 4 increased the pressure applied during liquid injection, resulting in excessive liquid injection and poorer performance compared to Examples 1-3. Therefore, similar to the method in Example 5, by adjusting the mesh size accordingly, battery performance can be further improved based on the existing methods.

[0140] The above detailed embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not limited to the scope of protection of the present invention. The present invention can be embodied in various forms without departing from its fundamental characteristics. Therefore, the embodiments described in this invention are for illustrative purposes only and not for limiting the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process, characterized in that, include: (1) Perovskite ink is spread onto a screen using a doctor blade, and a liquid film is formed on the screen by utilizing the surface tension of the perovskite ink and the adhesion between the mesh wall of the screen and the perovskite ink; wherein, the concentration of the perovskite ink is 0.5 to 2.0 mol / L, and the surface tension coefficient of the perovskite ink is >5 mN / m; the solvent of the perovskite ink is selected from at least one of dimethylformamide, N-methylformamide, dimethyl sulfoxide, γ-valerolactone, γ-butyrolactone, N-methyl-2-pyrrolidone, methanol, isopropanol, ethylene glycol, water, ethyl acetate, triethyl phosphate, 2-methoxyethanol, cyclopentyl methyl ether, and N-hydroxymethylacrylamide; (2) By squeezing the screen with a doctor blade, the adhesion between the perovskite ink and the mesh wall is changed, so that the liquid film falls from the mesh and forms a liquid bridge between it and the printing substrate. Under the action of capillary force, it is drawn in and penetrates into the printing substrate. After crystallization treatment, a perovskite light-absorbing layer is obtained. The surface of the printing substrate is a porous layer. The screen includes: a central mesh area and a non-porous area surrounding the central mesh area. The mesh size of the central mesh area is 18 to 250 micrometers.

2. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to claim 1, characterized in that, The wire mesh is made of at least one of a metal material and a polymer material; the metal material includes stainless steel or tungsten; the polymer material is polyester.

3. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to claim 1, characterized in that, The chemical composition of the perovskite material in the perovskite ink is ABX3; wherein A is a monovalent cation, and A is [CH(NH2)2]. + [CH3NH3] + [(CH2)3NH2] + [C3N2H5] + [(CH3CH2)NH3] + [(CH3)2NH2] + [(NH2)3C] + [(CH3)4N] + [C3H4NS] + [NC4H8] + [C7H7] + K + 、Rb + and Cs + At least one of them; B is Pb 2+ Sn 2+ Co 2+ Mn 2+ 、Ge 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Cu 2+ Fe 2+ Pd 2+ Eu 2+ Ni 2+ At least one of them; X is F - Cl - ,Br - I - and SCN - At least one of them.

4. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to any one of claims 1-3, characterized in that, The printing substrate includes: a substrate, a transparent conductive layer, a dense layer, an electron transport layer, an insulating layer, a hole transport layer, and a top electrode layer, with one side of the top electrode layer facing the screen and placed parallel to it; wherein, the electron transport layer, the insulating layer, the hole transport layer, and the top electrode layer all have a porous structure.

5. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to claim 4, characterized in that, The substrate is made of at least one of the following materials: metallic materials, inorganic non-metallic materials, and polymeric materials; the thickness of the substrate is 0.001 to 5 mm. The transparent conductive layer is made of materials including: indium tin oxide, zinc aluminum oxide, indium zinc oxide, fluorine-doped tin oxide, graphene and its derivatives; the thickness of the transparent conductive layer is 2-300 nanometers. The dense layer is made of metal oxide; the thickness of the dense layer is 2–100 nanometers. The electron transport layer is made of at least one of the following materials: titanium oxide and its dopants, tin oxide and its dopants, indium oxide and its dopants, zinc oxide and its dopants, cadmium sulfide and its dopants, zinc sulfide and its dopants, zinc selenide and its dopants, fullerene and its derivatives, graphene and its derivatives, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)methylborane; the thickness of the electron transport layer is 0.002–2 micrometers. The insulating layer is made of at least one of aluminum oxide, zirconium oxide, and magnesium oxide; the thickness of the insulating layer is 0.1 to 4 micrometers. The hole transport layer is made of at least one of the following materials: copper oxide, copper iodide, copper sulfide, cuprous thiocyanate, copper antimony sulfide, tungsten oxide, nickel oxide, molybdenum oxide, cerium oxide, vanadium oxide, manganese oxide, cobalt oxide, tungsten sulfide, and molybdenum sulfide; the thickness of the hole transport layer is 0.05 to 20 micrometers. The material of the top electrode layer includes at least one of graphite, carbon black, carbon nanotubes, carbon fiber, and graphene; the thickness of the top electrode layer is 1 to 200 micrometers.

6. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to claim 5, characterized in that, The metal oxide includes at least one of titanium oxide and its dopants, tin oxide and its dopants, and zinc oxide and its dopants.

7. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to claim 5, characterized in that, The electron transport layer has a pore size of 5–100 nanometers and a porosity of 10–80%. The insulating layer has a pore size of 0.001 to 1 micrometer and a porosity of 10 to 80%. The hole transport layer has a pore size of 0.001–1 micrometer and a porosity of 10–80%. The top electrode layer has a pore size of 0.001–6.5 micrometers and a porosity of 10–90%.

8. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to any one of claims 1-3, characterized in that, The distance between the screen and the printing substrate is 0 to 3 millimeters.

9. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to any one of claims 1-3, characterized in that, The perovskite ink is spread onto the screen using a doctor blade; the parameters of the doctor blade include: a moving speed of 0 to 300 mm / s and not 0, a gap between the doctor blade and the screen of 0 to 0.5 mm, an angle between the doctor blade and the screen of >0 degrees and <180 degrees, and a pressure of 0 Pa between the doctor blade and the screen of 0. The perovskite ink is dropped onto a non-porous area on one side of the screen, and then spread from the non-porous area on one side of the screen to the non-porous area on the other side of the screen using a doctor blade.

10. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to any one of claims 1-3, characterized in that, The liquid is applied by squeezing the wire mesh with a scraper. The parameters of the scraper include: a downward pressure of 0.01 to 0.6 MPa, a moving speed of 0 to 300 mm / s and not zero, and an angle between the scraper and the wire mesh of >0 degrees and <180 degrees.

11. The method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process according to claim 10, characterized in that, When residual liquid remains after the perovskite ink is spread onto the screen using a doctor blade, the doctor blade may or may not avoid the residual liquid during the process of pressing the screen with the doctor blade to release the ink.

12. The method for preparing a perovskite light-absorbing layer using the pseudo-screen printing process according to any one of claims 1-3, characterized in that, The crystallization treatment is performed at a temperature of room temperature to 300 degrees Celsius for a time of 2 to 1440 minutes.

13. A perovskite light-absorbing layer prepared by a method for preparing a perovskite light-absorbing layer using a pseudo-screen printing process according to any one of claims 1-12.

14. A perovskite battery, characterized in that, include: The perovskite light-absorbing layer according to claim 13.

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