Preparation method for perovskite thin film, and tandem solar cell

Abstract

The present application provides a preparation method for a perovskite thin film. An etching step is introduced in a conventional two-step method; in the first step, in the process of co-evaporating to form a lead iodide thin film, an organic additive is introduced; and in the second step, the organic additive in the lead iodide thin film is extracted using a dissolving solution, so that the lead iodide thin film of a porous structure is obtained, increasing the contact between the lead iodide thin film and an ammonium salt solution in the third step during spin-coating with the ammonium salt solution, thereby improving the adequacy of reaction; and a high-quality and low-defect density conformal perovskite thick film is formed on a textured substrate, thereby improving the performance of tandem solar cell devices obtained using the method.

Description

A method for preparing perovskite thin film and stacked solar cell

[0001] This application claims priority to Chinese patent application No. 2024103999177, filed with the Patent Office of China on April 3, 2024, entitled “A method for preparing a perovskite thin film and a stacked solar cell”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention mainly relates to the technical field of solar cells, and in particular to a method for preparing a perovskite thin film and a stacked solar cell. Background Art

[0003] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0004] Solar energy, a sought-after new clean energy source, boasts abundant resources and low costs. Converting solar energy into electricity using photovoltaic cells is currently one of the most efficient ways to utilize solar energy. Monocrystalline and polycrystalline silicon solar cells have relatively mature industrial technologies. In recent years, perovskite solar cells have garnered widespread attention from both the scientific and industrial communities due to their advantages, including adjustable band gaps, low exciton binding forces, and high photoelectric conversion efficiency.

[0005] Most existing crystalline silicon / perovskite tandem solar cells are fabricated using polished crystalline silicon base cells. This is because existing perovskite film formation methods are generally targeted at polished substrates, whereas the surfaces of crystalline silicon cells currently commercialized on a large scale are mostly textured. Textured surfaces significantly reduce the device's reflection of incident light and enhance light absorption, an essential requirement for high-efficiency solar cells. Consequently, current crystalline silicon / perovskite tandem solar cells based on polished crystalline silicon base cells generally suffer from high light absorption losses and low short-circuit current density.

[0006] In this regard, the use of textured crystalline silicon substrates is an inevitable option for further improving the performance of crystalline silicon / perovskite tandem solar cells. To prepare conformal, fully covered perovskite films on textured crystalline silicon substrates, a two-step evaporation and solution method is commonly used. In the first step, a conformal lead iodide or lead iodide-cesium bromide mixed film is prepared by evaporation. In the second step, a mixed ammonium salt solution reacts with the evaporated film to form a conformal perovskite film.

[0007] However, this traditional two-step method produces conformal perovskite films with a large amount of lead iodide residue because the lead iodide hardly reacts completely with the ammonium salt solution. This free lead iodide forms numerous defects within the perovskite film, resulting in low-quality perovskite films and thus affecting device performance. Application Contents

[0008] The present invention aims to overcome the problem that existing perovskite film preparation methods cannot produce high-quality, low-defect-density conformal perovskite films. A perovskite film preparation method and a tandem solar cell are proposed. This method introduces organic vapor deposition into the first step of the conventional two-step co-evaporation method. Subsequently, a second step of dissolving and etching to remove organic matter is added, thereby converting the dense lead iodide film formed by evaporation into a loose, porous film. This method increases the contact surface area of ​​the lead iodide film with the ammonium salt solution in the third step, thereby allowing the lead iodide to react more completely with the ammonium salt solution, forming a high-quality, low-defect-density conformal perovskite film and improving device performance. The tandem solar cell prepared by this method has higher stability and light conversion efficiency.

[0009] To achieve the above objectives, the present invention provides the following specific solutions.

[0010] A method for preparing a perovskite film comprises the following steps:

[0011] A suede substrate is provided, lead iodide, cesium bromide and an organic additive are co-evaporated on the suede substrate to form a lead iodide film; a dissolved solution is coated on the lead iodide film to obtain a porous lead iodide film, an ammonium salt solution is spin-coated on the porous lead iodide film, and annealing is performed to obtain a perovskite absorption layer.

[0012] The organic additive is an organic amine halide, including but not limited to at least one of propylenediamine bromide (PDADBr), butylammonium chloride (BACl), butylammonium bromide (BABr), butylammonium iodide (BAI), N,N-dimethyl-1,3-propylenediamine hydrochloride (DMePDADCl), and dodecanediamine bromide (DDDADBr);

[0013] In this embodiment, the dissolving solution is at least one of ethanol, isopropanol, and methanol;

[0014] In one embodiment, the dissolved solution can be coated on the lead iodide film by spin coating, with a spin coating speed of 1200-6000 rpm and a spin coating time of 20-120 s. After the spin coating is completed, an annealing operation is performed, with an annealing temperature of 50-150° C. and an annealing time of 5-40 min. Alternatively, an immersion coating method can be used, in which a sample prepared with a lead iodide film is immersed in the dissolved solution for 0-40 min, taken out and annealed, with an annealing temperature of 50-150° C. and an annealing time of 5-40 min. This step converts the dense lead iodide film into a porous lead iodide film with a porous loose structure.

[0015] In one embodiment, the evaporation rate of lead iodide is controlled at 0-10 A / s, the evaporation rate of cesium bromide is controlled at 0-10 A / s, the evaporation rate of the organic additive is controlled at 0-10 A / s, and the total evaporation time is controlled between 0 and 10000 s.

[0016] Preferably, by controlling the evaporation rates of different materials, the content ratio of lead iodide to cesium bromide is between 10:1 and 2:1, and the ratio of the organic additive to lead iodide and cesium bromide is between 1:100 and 1:5.

[0017] The ammonium salt solution is prepared by dissolving formamidine iodide (FAI), formamidine bromide (FABr) and methylammonium chloride (MACl) in an organic solvent in a certain proportion, wherein the volume ratio of FAI and FABr is between 10:1 and 1:10; the volume ratio of MACl to the two ammonium salt additives FAI and FABr is between 0% and 50%, and the solution concentration is controlled between 0.5-2 M; the organic solvent includes at least one of ethanol, isopropanol, methanol, dimethylformamide (DMF), g-butyrolactone (GBL), dimethyl sulfoxide (DMSO) and N,N-dimethylacetamide (DMA), and the solvent volume ratio is between 0-3:10-7.

[0018] In one embodiment, the spin coating speed of the ammonium salt solution is 1200-6000 rpm, the spin coating time is 20-120 s, and after the spin coating is completed, annealing is performed at an annealing temperature of 50-150° C. and an annealing time of 5-40 min.

[0019] In one embodiment, the preparation of the suede substrate comprises:

[0020] A textured silicon substrate is provided, and a base passivation layer, a P-type base doping layer, and a first conductive layer are sequentially prepared on one side of the textured silicon substrate; and a base surface passivation layer, an N-type base doping layer, a tunneling layer, and a hole transport layer are sequentially prepared on the other side of the textured silicon substrate to obtain the textured substrate, wherein the perovskite absorption layer is formed on the hole transport layer.

[0021] Specifically, the first conductive layer includes a first conductive transparent layer and a first metal electrode layer sequentially formed on the P-type doped layer.

[0022] In one embodiment, the perovskite thin film preparation method further includes sequentially forming a passivation layer, an electron transport layer, a buffer layer, a second conductive layer, and an anti-reflection layer on the surface of the perovskite absorption layer.

[0023] Specifically, the second conductive layer includes a second conductive transparent layer and a second metal electrode layer sequentially formed on the buffer layer.

[0024] The present invention also provides a stacked solar cell prepared by the above method, comprising a velvet substrate; and a perovskite absorption layer, a passivation layer, an electron transport layer, a buffer layer, a second conductive layer and an anti-reflection layer sequentially arranged on the surface of the velvet substrate.

[0025] Specifically, the second conductive layer includes a second conductive transparent layer and a second metal electrode layer sequentially disposed on the buffer layer.

[0026] The textured substrate includes a textured crystalline silicon layer; a tunneling layer and a hole transport layer sequentially arranged on one surface of the textured crystalline silicon layer, the perovskite absorption layer is arranged on the hole transport layer; and a first conductive layer arranged on the other surface of the textured crystalline silicon layer.

[0027] Specifically, the first conductive layer includes a first conductive transparent layer and a first metal electrode layer sequentially provided on the surface of the textured crystalline silicon layer.

[0028] Specifically, the textured crystalline silicon layer includes a textured silicon substrate; and a base passivation layer and a P-type base doping layer sequentially arranged on one surface of the textured silicon substrate, and the first conductive layer is arranged on the P-type base doping layer; and a base surface passivation layer and an N-type base doping layer sequentially prepared on the other surface of the textured silicon substrate, and the tunneling layer is arranged on the N-type base doping layer.

[0029] This embodiment provides a method for preparing a perovskite thin film, which introduces an etching step into the traditional two-step method. In the first step, an organic additive is introduced during the co-evaporation of a lead iodide thin film. In the second step, a dissolving solution is used to absorb the organic additive in the lead iodide thin film, thereby obtaining a lead iodide thin film with a porous structure. The contact with the ammonium salt solution during spin coating in the third step is increased, thereby improving the sufficiency of the reaction, promoting the formation of a higher-quality, lower-defect-density conformal perovskite thick film on a suede substrate, and improving the performance of the battery device obtained using this method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a schematic diagram of the steps of a method for preparing a perovskite thin film provided in an embodiment of the present invention.

[0031] FIG2 is a schematic diagram of the structure of a stacked solar cell provided by an embodiment of the present invention.

[0032] 1. Velvet substrate; L1, lead iodide film; L2, porous lead iodide film; 2. Perovskite absorption layer.

[0033] 10. First conductive layer; 11. Textured crystalline silicon layer; 12. Tunneling layer; 13. Hole transport layer; 21. Passivation layer; 22. Electron transport layer; 23. Buffer layer; 24. Second conductive layer; 25. Anti-reflection layer.

[0034] 101. First metal electrode layer; 102. First conductive transparent layer; 111. P-type base doping layer; 112. Base passivation layer; 113. Textured silicon substrate; 114. Base surface passivation layer; 115. N-type base doping layer; 241. Second metal electrode layer; 242. Second conductive transparent layer. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0036] In the description of the present invention, unless otherwise specified, "plurality" means two or more; the terms "center", "longitudinal", "lateral", "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0037] Referring to FIG1 , a method for preparing a perovskite thin film according to an embodiment of the present invention includes the following steps:

[0038] A suede substrate 1 is provided, on which lead iodide, cesium bromide and an organic additive are co-evaporated to form a lead iodide film L1; a dissolved solution is coated on the lead iodide film L1 to obtain a porous lead iodide film L2; an ammonium salt solution is spin-coated on the porous lead iodide film L2, and annealing is performed to obtain a perovskite absorption layer 2.

[0039] The organic additive is an organic amine halide, including but not limited to at least one of propylenediamine bromide (PDADBr), butylammonium chloride (BACl), butylammonium bromide (BABr), butylammonium iodide (BAI), N,N-dimethyl-1,3-propylenediamine hydrochloride (DMePDADCl), and dodecanediamine bromide (DDDADBr);

[0040] In this embodiment, the dissolving solution is at least one of ethanol, isopropanol, and methanol. After the lead iodide film is prepared, the film contains organic additives that can be absorbed by the applied dissolving solution, leaving a porous structure on the film, achieving an etching effect and obtaining a porous lead iodide film. The porous structure can increase contact with the ammonium salt solution and improve the completeness of the reaction.

[0041] In one embodiment, the dissolved solution can be coated on the lead iodide film L1 by spin coating, with a spin coating speed of 1200-6000 rpm and a spin coating time of 20-120 s. After the spin coating is completed, an annealing operation is performed, and the annealing temperature is 50-150°C and the annealing time is 5-40 min. It can also be coated by immersion method, and the sample prepared with the lead iodide film L1 is immersed in the dissolved solution for 0-40 min, taken out and annealed, and the annealing temperature is 50-150°C and the annealing time is 5-40 min. This step transforms the dense lead iodide film L1 into a porous lead iodide film L2 with a porous and loose structure.

[0042] In one embodiment, the evaporation rate of lead iodide is controlled at 0-10 A / s, the evaporation rate of cesium bromide is controlled at 0-10 A / s, the evaporation rate of the organic additive is controlled at 0-10 A / s, and the total evaporation time is controlled between 0 and 10000 s.

[0043] Preferably, by controlling the evaporation rates of different materials, the content ratio of lead iodide to cesium bromide is between 10:1 and 2:1, and the ratio of the organic additive to lead iodide and cesium bromide is between 1:100 and 1:5.

[0044] The ammonium salt solution is prepared by dissolving formamidine iodide (FAI), formamidine bromide (FABr) and methylammonium chloride (MACl) in an organic solvent in a certain proportion, wherein the volume ratio of FAI and FABr is between 10:1 and 1:10; the volume ratio of MACl to the two ammonium salt additives FAI and FABr is between 0% and 50%, and the solution concentration is controlled between 0.5-2 M; the organic solvent includes at least one of ethanol, isopropanol, methanol, dimethylformamide (DMF), g-butyrolactone (GBL), dimethyl sulfoxide (DMSO) and N,N-dimethylacetamide (DMA), and the solvent volume ratio is between 0-3:10-7.

[0045] In one embodiment, the spin coating speed of the ammonium salt solution is 1200-6000 rpm, the spin coating time is 20-120 s, and after the spin coating is completed, annealing is performed at an annealing temperature of 50-150° C. and an annealing time of 5-40 min.

[0046] In this embodiment, the velvet base 1 is a layer film with a velvet structure on the surface. In the production and application of solar cells, the irregular surface of the velvet structure can increase the number of reflections of sunlight on the surface, effectively reduce the surface reflectivity of the solar cell, and increase the light absorption coefficient of the device, thereby increasing the photoelectric conversion efficiency of the device. The velvet base 1 described in this application has a velvet structure, which can also reduce light reflection.

[0047] In one embodiment, the preparation of the velvet base 1 includes: providing a velvet silicon substrate 113, sequentially preparing a base passivation layer 112, a P-type base doping layer 111 and a first conductive layer 10 on one side of the velvet silicon substrate 113, and sequentially preparing a base surface passivation layer 114, an N-type base doping layer 115, a tunneling layer 12 and a hole transport layer 13 on the other side of the velvet silicon substrate 113 to obtain the velvet base 1, wherein the perovskite absorption layer 2 is formed on the hole transport layer 13, and the first conductive layer 10 includes a first conductive transparent layer 102 and a first metal electrode layer 101 sequentially formed on the P-type base doping layer 111.

[0048] In this embodiment, the textured silicon substrate 113 has a textured surface on its surface. On this basis, each film layer formed on the two surfaces of the textured silicon substrate 113 also has a textured structure; specifically, the textured surface of the textured silicon substrate 113 can be prepared by anisotropically etching a silicon wafer with an alkaline solution.

[0049] The base passivation layer 112 and the base surface passivation layer 114 formed on the two surfaces of the textured silicon substrate 113 are both passivation structures, which can saturate the dangling bonds at the semiconductor surface, reduce surface activity, increase the surface cleaning process, and avoid the formation of recombination centers due to the introduction of impurities in the surface layer, thereby reducing the surface recombination rate of minority carriers; specifically, the base passivation layer 112 and the base surface passivation layer 114 can be formed by methods such as vapor deposition and atomic layer deposition.

[0050] In this embodiment, the P-type base doping layer 111 and the N-type base doping layer 115 can be formed by diffusion. Specifically, a phosphorus source / nitrogen source is diffused on the textured silicon substrate 113 to form a doping structure, thereby obtaining the P-type base doping layer 111 and the N-type base doping layer 115 respectively.

[0051] The first conductive transparent layer 102 can be formed by magnetron sputtering. The substrate sample to be prepared is placed in a magnetron sputtering device, the power is controlled between 50 and 200 W, a target is set, and the first conductive transparent layer 102 is sputtered. The first metal electrode layer 101 is formed by evaporation. The substrate sample to be prepared is placed on a mask plate for evaporation. The evaporation vacuum is 5×10 -5 ~2×10 -4 Pa, the evaporation temperature is 500-2000° C., the evaporation rate is 0.1-5 Å / S, and the metal material is evaporated to form the first metal electrode layer 101.

[0052] In this embodiment, the tunneling layer 12 is prepared by atomic layer deposition, magnetron sputtering or wet chemical method, which can eliminate the electrical mismatch and device instability problems caused by direct series connection of crystalline silicon cells and perovskite cells.

[0053] In this embodiment, the hole transport layer 13 is prepared by spin coating, and the hole transport layer dispersion is evenly coated on the surface of the tunneling layer 12. The spin coating speed is 1000-5000 rpm, and the spin coating time is 10-100 s. After the spin coating is completed, an annealing operation is performed. The annealing temperature is 300-600° C. and the annealing time is 10-50 min to obtain the hole transport layer 13.

[0054] In this embodiment, the hole transport layer 13 can also be prepared by magnetron sputtering. The substrate sample to be prepared is placed in a magnetron sputtering device, and the power is controlled to be 30-90W to obtain the hole transport layer 13 by sputtering.

[0055] In one embodiment, the perovskite thin film preparation method also includes sequentially forming a passivation layer 21, an electron transport layer 22, a buffer layer 23, a second conductive layer 24 and an anti-reflection layer 25 on the surface of the perovskite absorption layer 2, and the second conductive layer 24 includes a second conductive transparent layer 242 and a second metal electrode layer 241 sequentially formed on the buffer layer 23.

[0056] The passivation layer 21 can be prepared by evaporation, wherein the passivation layer material is evaporated onto the surface of the perovskite absorption layer 2, and the evaporation vacuum degree is 1~5×10 -4 Pa, the evaporation temperature is 50-400°C, the evaporation rate is 0.05-1 Å / S, and after the evaporation is completed, an annealing operation is performed, the annealing temperature is 0-150°C, and the annealing time is 0-30 min to obtain the passivation layer 21.

[0057] The passivation layer 21 can also be prepared by a spin coating method, wherein the passivation layer dispersion is evenly coated on the surface of the perovskite absorption layer 2, ultrasonically dissolved and spin-coated, the ultrasonic time is 0-30 min, the spin coating speed is 1000-7000 rpm, and the spin coating time is 20-120 s; after the spin coating is completed, an annealing operation is performed, the annealing temperature is 40-160° C., and the annealing time is 5-40 min to obtain the passivation layer 21.

[0058] The passivation layer 21 can also be prepared by spraying, spraying the passivation layer dispersion on the surface of the perovskite absorption layer at a spraying rate of 1-100 cm / s. After spraying, annealing is performed at a temperature of 20-170° C. and a time of 0-30 min to obtain the passivation layer 21.

[0059] The passivation layer 21 is used to reduce the surface activity of the perovskite absorption layer, thereby reducing the surface carrier recombination efficiency, thereby improving the photoelectric conversion efficiency of the device.

[0060] The electron transport layer 22 is prepared by spin coating, and the electron transport layer dispersion is evenly coated on the surface of the passivation layer 21 at a spin coating speed of 500-4000 rpm and a spin coating time of 10-80 s to obtain the electron transport layer 22.

[0061] The electron transport layer 22 can also be prepared by evaporation, wherein the electron transport layer material is evaporated onto the surface of the passivation layer 21, and the evaporation vacuum degree is 5×10 -5 ~5×10 -4 Pa, the evaporation temperature is 100-400° C., and the evaporation rate is 0.05-1 Å / S to obtain the electron transport layer 22.

[0062] The buffer layer 23 is prepared by atomic layer deposition. The buffer layer material is deposited on the surface of the electron transport layer 22 using an atomic layer deposition device. The deposition vacuum is 0-1×10 4 Pa, the deposition pipeline temperature is between 50 and 150° C., the deposition chamber temperature is between 40 and 150° C., and the buffer layer 23 is obtained.

[0063] The buffer layer 23 can also be prepared by evaporation, wherein the buffer layer material is evaporated onto the surface of the electron transport layer 22, and the evaporation vacuum is 6×10 -5 ~4×10 -4 Pa, the evaporation temperature is 100~500℃, and the evaporation rate is 0.05~1 Å / S to obtain the buffer layer 23.

[0064] In this embodiment, the second conductive layer 24 can be prepared by the same method as the first conductive layer 10. Specifically, the second conductive transparent layer 242 can be formed by magnetron sputtering. The substrate sample to be prepared is placed in a magnetron sputtering device, the power is controlled between 50 and 200 W, a target material is set, and the second conductive transparent layer 242 is sputtered. The first metal electrode layer 101 is formed by evaporation. The substrate sample to be prepared is placed on a mask plate for evaporation. The evaporation vacuum degree is 5×10 -5 ~2×10 -4 Pa, the evaporation temperature is 500-2000° C., the evaporation rate is 0.1-5 Å / S, and the metal material is evaporated to form the second metal electrode layer 241 .

[0065] The anti-reflection layer 25 is prepared by magnetron sputtering or evaporation.

[0066] This embodiment provides a method for preparing a perovskite thin film, which introduces an etching step into the traditional two-step method. In the first step, an organic additive is introduced during the co-evaporation of a lead iodide thin film. In the second step, a dissolving solution is used to absorb the organic additive in the lead iodide thin film, thereby obtaining a lead iodide thin film with a porous structure. The contact with the ammonium salt solution during spin coating in the third step is increased, thereby improving the sufficiency of the reaction, promoting the formation of a higher-quality, lower-defect-density conformal perovskite thick film on a suede substrate, and improving the performance of the battery device obtained using this method.

[0067] Referring to Figure 2, an embodiment of the present invention further provides a stacked solar cell obtained by the above-mentioned perovskite thin film preparation method, comprising a suede substrate 1; and a perovskite absorption layer 2, a passivation layer 21, an electron transport layer 22, a buffer layer 23, a second conductive layer 24 and an anti-reflection layer 25 sequentially arranged on the surface of the suede substrate.

[0068] Specifically, the second conductive layer 24 includes a second conductive transparent layer 242 and a second metal electrode layer 241 sequentially disposed on the buffer layer 23 .

[0069] In this embodiment, the surface of the velvet substrate 1 has a velvet structure. Therefore, the perovskite absorption layer 2, the passivation layer 21, the electron transport layer 22, the buffer layer 23, the second conductive layer 24 and the anti-reflection layer 25 formed on the surface of the velvet substrate 1 are also film layers with a velvet structure. The irregular surface of the velvet structure can increase the number of reflections of sunlight on the surface, effectively reduce the surface reflectivity of the solar cell, and improve the light absorption coefficient of the device, thereby increasing the photoelectric conversion efficiency of the device.

[0070] In this embodiment, the perovskite absorption layer 2 is specifically an ABX3 structure, and the A position is an organic cation, including CH3NH3 +(MA + ), NH2CH=NH2 + (FA + ), CH3CH2NH3 + or Cs + At least one of .

[0071] The B position is a metal cation, including Pb 2+ 、Sn 2+ At least one of .

[0072] The X position is a halogen anion, including F - 、Cl - Br - , I - At least one of .

[0073] The passivation layer 21 on the perovskite absorption layer 2 can reduce the surface activity of the perovskite absorption layer 2, reduce the surface carrier recombination efficiency, and thus improve the photoelectric conversion efficiency of the device; specifically, the passivation layer 21 is composed of at least one of propylenediamine iodide, propylenediamine bromide (PDADBr), butylammonium chloride (BACl), butylammonium bromide (BABr), butylammonium iodide (BAI), N,N-dimethyl-1,3-propylenediamine hydrochloride (DMePDADCl), dodecadiamine bromide (DDDADBr), magnesium fluoride, lithium fluoride (LiF), and sodium fluoride (NaF).

[0074] The electron transport layer 22 can effectively transport electrons and block holes. Specifically, the electron transport layer is made of zinc oxide (ZnO), tin dioxide (SnO2), titanium dioxide (TiO2), [6,6]-phenyl C61 butyric acid methyl ester (PC 61 BM), carbon 60 (C 60 ), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).

[0075] The buffer layer 23 can effectively improve problems such as band mismatch between interfaces, carrier recombination and chemical reactions, thereby improving the charge separation and collection efficiency in the perovskite battery, and effectively improving interface and stability problems. Specifically, the buffer layer 23 is composed of at least one of zinc oxide (ZnO), tin dioxide (SnO2), and titanium dioxide (TiO2).

[0076] The second conductive layer 24 is composed of a second conductive transparent layer 242 and a second metal electrode layer 241, which plays the role of conducting electrons and outputting current. Specifically, the second metal electrode layer 241 is composed of at least one of silver (Ag), gold (Au), copper (Cu), aluminum (Al), and carbon (C); the second conductive transparent layer 242 is composed of at least one of indium tin oxide (ITO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO).

[0077] The anti-reflection layer 25 is at least one of magnesium fluoride, lithium fluoride (LiF), sodium fluoride (NaF), and silicon oxide (SiO2);

[0078] In this embodiment, the textured substrate 1 includes a textured crystalline silicon layer 11; a tunneling layer 12 and a hole transport layer 13 sequentially arranged on one surface of the textured crystalline silicon layer 11, and the perovskite absorption layer 2 is arranged on the hole transport layer 13; and a first conductive layer 10 arranged on the other surface of the textured crystalline silicon layer 11, and the first conductive layer 10 includes a first conductive transparent layer 102 and a first metal electrode layer 101 sequentially arranged on the surface of the textured crystalline silicon layer 11.

[0079] Specifically, the textured crystalline silicon layer 11 includes a textured silicon substrate 113; and a base passivation layer 112 and a P-type base doping layer 111 sequentially arranged on one surface of the textured silicon substrate 113, and the first conductive layer 10 is arranged on the P-type base doping layer 111; and a base surface passivation layer 114 and an N-type base doping layer 115 sequentially prepared on the other surface of the textured silicon substrate 113, and the tunneling layer 12 is arranged on the N-type base doping layer 115.

[0080] The tunneling layer 12 may be made of oxides such as silicon dioxide, and may generate a tunneling current at the contact position of the stacked battery to connect the two sub-batteries.

[0081] The hole transport layer 13 is made of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly-3-hexylthiophene (P3HT), nickel oxide (NiO x ), molybdenum oxide (MoO x ), cuprous iodide (CuI), and cuprous thiocyanate (CuSCN), can transport holes and block electron transmission.

[0082] In this embodiment, the hole transport layer 13, perovskite absorption layer 2, passivation layer 21, and electron transport layer 22 constitute a perovskite cell. The P-type base doping layer 111, base passivation layer 112, textured silicon substrate 113, base surface passivation layer 114, and N-type base doping layer 115 constitute a textured crystalline silicon layer 11. The textured crystalline silicon layer 11 is a crystalline silicon cell, specifically, a crystalline silicon cell formed of single crystal silicon, polycrystalline silicon, or amorphous silicon semiconductors. Connecting the two cells to form a series structure through a tunneling layer 12 can achieve excellent surface passivation and selective carrier collection, thereby improving device performance.

[0083] The present invention provides a stacked solar cell, comprising a velvet substrate 1, a perovskite absorption layer 2, a passivation layer 21, an electron transport layer 22, a buffer layer 23, a second conductive layer 24, and an anti-reflection layer 25. During the preparation of the perovskite absorption layer 2, a perovskite film is prepared by evaporating an organic additive and etching. After a lead iodide film containing an organic additive is formed on the substrate, it is dissolved to obtain a porous lead iodide film, and then an ammonium salt solution is spin-coated and annealed. The film formed by this process has fewer defects and has higher open circuit voltage, photoelectric conversion efficiency, and device stability.

[0084] The following specific embodiments and comparative examples are provided to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0085] Example 1: Solar cell device obtained based on traditional perovskite film preparation method

[0086] This embodiment provides a stacked solar cell, including a first metal electrode layer 101, a first conductive transparent layer 102, a P-type base doping layer 111, a base passivation layer 112, a textured silicon substrate 113, a base surface passivation layer 114, an N-type base doping layer 115, a tunneling layer 12, a hole transport layer 13, a perovskite absorption layer 2, a passivation layer 21, an electron transport layer 22, a buffer layer 23, a second conductive transparent layer 242, a second metal electrode layer 241, and an anti-reflection layer 25. The method is as follows:

[0087] Step 1: providing a textured silicon substrate 113, sequentially preparing a base passivation layer 112 and a P-type base doping layer 111 on the back side of the textured silicon substrate 113, and sequentially preparing a base surface passivation layer 114 and an N-type base doping layer 115 on the other side.

[0088] Step 2: Using magnetron sputtering, an ITO target is set, the power is controlled to 60 W, the operation time is 1.5 hours, and the first conductive transparent layer 102 is formed on the P-type base doped layer 111.

[0089] Step 3: Using the evaporation method, place the substrate sample prepared in the previous step into the evaporation chamber and wait for the evaporation vacuum to reach 2×10 -4 Pa, the evaporation voltage is adjusted to the evaporation temperature, the evaporation rate is controlled at 2.5 Å / s, and silver is evaporated to the first conductive transparent layer 102 to obtain the first metal electrode layer 101.

[0090] Step 4: Using magnetron sputtering, place the substrate sample prepared in the previous step on the mask and then place it in the magnetron sputtering equipment, control the power to 60W, run for 1 hour, and form a tunneling layer 12 on the N-type substrate doping layer 115. The tunneling layer 12 is silicon dioxide.

[0091] Step 5: Treat the substrate sample prepared in the previous step with UV-Ozone for 15 minutes, and use the spin coating method to prepare a hole transport layer dispersion. Weigh 0.05 mol NiOx powder and dissolve it in 1 ml ultrapure water, and ultrasonically vibrate for 20 minutes; evenly coat the hole transport layer dispersion on the surface of the tunneling layer 12, set the spin coating speed to 2000 rpm, the spin coating time to 40 seconds, and the solution volume to 100 ul; after the spin coating is completed, perform annealing operation at an annealing temperature of 450°C and an annealing time of 30 minutes to obtain a hole transport layer 13.

[0092] Step 6: Using a co-evaporation method, lead iodide and cesium bromide are evaporated on the surface of the hole transport layer 13 to form a lead iodide film L1. The evaporation rate of lead iodide is 8A / s, the evaporation rate of cesium bromide is controlled at 0.8A / s, the total evaporation time is 1000s, the content ratio of lead iodide to cesium bromide is controlled at 10:1, and the thickness of the formed film is 440nm; formamidine iodide (FAI), formamidine bromide (FABr), and methylamine chloride (MACl) are added at a certain The ratio of FAI and FABr is dissolved in an organic solvent at 1:4.7, the ratio of methylamine chloride (MACl) to the other two ammonium salt additives is 10%wt, and the solution concentration is controlled at 1M to obtain an ammonium salt solution; the ammonium salt solution is spin-coated on the surface of the lead iodide film L1 at a spin-coating speed of 5000 rpm and a spin-coating time of 30s, and an annealing operation is performed at an annealing temperature of 150°C and an annealing time of 10min to obtain a perovskite absorption layer 2.

[0093] Step 7: Using the evaporation method, weigh 3 mg of propylene diamine iodide and place it in a crucible. Place the substrate sample prepared in the previous step on the mask and place it in the evaporation chamber. Wait until the evaporation vacuum reaches 2×10 -4Pa, the evaporation voltage is adjusted to the evaporation temperature, the evaporation rate is controlled at 0.1Å / S, and propylene diamine iodide is evaporated onto the perovskite absorption layer 2. After the annealing table temperature is set to 100°C, and an annealing operation is performed for 8 minutes to obtain the passivation layer 21.

[0094] Step 8: Using the evaporation method, place the substrate sample prepared in the previous step on the mask and put it into the evaporation chamber until the evaporation vacuum degree reaches 1×10 -4 Pa, the evaporation voltage is adjusted to the evaporation temperature, the evaporation rate is controlled at 0.1-0.15Å / S, and C60 is evaporated onto the passivation layer 21 to obtain the electron transport layer 22.

[0095] Step 9: Using atomic layer deposition, set the vacuum degree of the atomic layer deposition equipment to 0.5×10 4 Pa, the deposition pipeline temperature is 60° C., the deposition chamber temperature is 70° C., SnO 2 is evaporated onto the electron transport layer 22 to obtain the buffer layer 23 .

[0096] Step 10: Using magnetron sputtering, setting an IZO target, controlling the power to 50 W, and running for 1 hour, a second conductive transparent layer 242 is formed on the buffer layer 23 .

[0097] Step 11: Using the evaporation method, place the substrate sample prepared in the previous step into the evaporation chamber and wait for the evaporation vacuum to reach 2×10 -4 Pa, the evaporation voltage is adjusted to the evaporation temperature, the evaporation rate is controlled at 2.5 Å / S, and silver is evaporated to the second conductive transparent layer 242 to obtain the second metal electrode layer 241.

[0098] Step 12: Using an evaporation method, magnesium fluoride is evaporated on the second metal electrode layer 241 at an evaporation rate of 2.5 Å / s and a thickness of 100 nm, thereby finally obtaining a stacked solar cell.

[0099] Example 2: Solar cell device obtained based on the preparation method of perovskite film containing 5% organic additives

[0100] Referring to Figures 1-2, this embodiment provides a stacked solar cell having the same device structure as that of Example 1. However, the difference between the preparation method and that of Example 1 lies in step 6. In this embodiment, step 6 is as follows:

[0101] Lead iodide, cesium bromide, and propylene diamine bromide are evaporated on the surface of the hole transport layer 13 by a co-evaporation method to form a lead iodide film L1. The evaporation rate of lead iodide is 8A / s, the evaporation rate of cesium bromide is controlled at 0.8A / s, the evaporation rate of propylene diamine bromide is 0.4A / s, the total evaporation time is 1000s, the content ratio of lead iodide to cesium bromide is controlled at 10:1, and the ratio of propylene diamine bromide to lead iodide and cesium bromide is 5:100. The thickness of the formed film is 440nm. Isopropyl alcohol (IPA), which can dissolve organic additives but cannot dissolve lead iodide and cesium bromide, is evenly coated on the surface of the lead iodide film L1 prepared in the first step to remove the organic additives in the film, and an annealing operation is performed. The annealing temperature is 100°C and the annealing time is 10 min; this step transforms the dense lead iodide film L1 into a porous lead iodide film L2; formamidine iodide (FAI), formamidine bromide (FABr), and methylammonium chloride (MACl) are dissolved in an organic solvent in a certain proportion, the ratio of FAI and FABr is between 1:4.7, the ratio of methylammonium chloride (MACl) to the other two ammonium salt additives is 10%wt, and the solution concentration is controlled at 1M to obtain an ammonium salt solution; the ammonium salt solution is spin-coated on the surface of the porous lead iodide film L2 at a spin-coating speed of 5000 rpm and a spin-coating time of 30s, and an annealing operation is performed at an annealing temperature of 150°C and an annealing time of 10min to obtain a perovskite absorption layer 2.

[0102] Example 3 Battery device obtained based on the preparation method of perovskite film containing 10% organic additives

[0103] This embodiment provides a stacked solar cell having the same device structure as that of Example 2, but the difference in the preparation method from that of Example 2 is that the evaporation rate of propylenediamine bromide in step 6 is 0.8 A / s, and the ratio of propylenediamine bromide to lead iodide and cesium bromide is 1:10.

[0104] Example 4: Solar cell device obtained based on the preparation method of perovskite film containing 20% ​​organic additives

[0105] This embodiment provides a stacked solar cell having the same device structure as that of Example 2, but the difference in the preparation method from that of Example 2 is that the evaporation rate of propylenediamine bromide in step 6 is 1.6 A / s, and the ratio of propylenediamine bromide to lead iodide and cesium bromide is 1:5.

[0106] A solar simulator was used to perform a standard solar intensity calibration and a solar light intensity calibration was performed on an area of ​​1.0 cm 2 The devices obtained in Examples 1 to 4 above were subjected to IV testing, with the starting voltage set to 1.95V, the cut-off voltage set to 0V, the range set to 100 mA, and the results rounded to two decimal places. The test results are shown in the following table:

[0107] Device photoelectric conversion efficiency (%) Open circuit voltage (v) Short circuit current density (mA / cm 2 ) Decay rate / stability (% / year) Example 1 26.20 1.86 18.26 4.92 Example 2 31.38 2.10 21.34 0.92 Example 3 33.68 2.11 21.63 0.52 Example 4 30.34 2.09 21.16 1.02

[0108] Can learn from the test data obtained by experiment, in embodiment 1, based on the prepared perovskite film of conventional method, because its first step film and second step ammonium salt solution reaction are incomplete.Ammonium salt solution is difficult to penetrate into the film bottom prepared by the first step, and the perovskite film inside and the bottom of its formation have a large amount of lead iodides to remain, and film quality is low.In embodiment 2-4, through the first step lead iodide film of co-steaming dissolution solution three-step method processing, because its porous characteristic has larger reaction surface area, can react with the ammonium salt solution of the second step more completely.Ammonium salt solution also can better contact with the bottom by porous structure and lead iodide film inside.Based on the prepared perovskite film of selective dissolution process, inside does not have lead iodide to remain, and film quality is high.

[0109] In terms of device performance, the stacked devices of Examples 2-4, prepared using the solution process, all exhibited significantly higher photoelectric conversion efficiency, short-circuit current, and open-circuit voltage than the stacked device of Example 1, prepared using conventional methods. Furthermore, the stacked devices of Examples 2-4 also exhibited significantly higher stability than that of Example 1. This is demonstrated by the device degradation rate of Example 1, which was as high as 4.9% per year, while the degradation rates of the stacked devices of Examples 2-4 were all less than 1.1% per year.

[0110] The invention also optimizes the organic doping ratio for the three-step co-evaporation and dissolution process. Optimization results show that for this process, an organic doping ratio of 1:10 achieves optimal results. This is reflected in the stacked device in Example 3, based on these optimized parameters, achieving higher photoelectric conversion efficiency and open-circuit voltage than Examples 2 and 4.

[0111] The above embodiments are only preferred implementation modes of the present invention. It should be pointed out that for ordinary technicians in this technical field, various changes, modifications, replacements and deformations can be made to these embodiments without departing from the principles of the present invention. These technical solutions that are equivalent to the claims of the present invention all fall within the scope of protection of the present invention, and the scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a perovskite thin film, characterized in that: Including steps: A suede substrate is provided, lead iodide, cesium bromide and an organic additive are co-evaporated on the suede substrate to form a lead iodide film; a dissolved solution is coated on the lead iodide film to obtain a porous lead iodide film, an ammonium salt solution is spin-coated on the porous lead iodide film, and annealing is performed to obtain a perovskite absorption layer.

2. The method for preparing a perovskite thin film according to claim 1, wherein: The organic additive is an organic amine halide, including at least one of propylenediamine bromide (PDADBr), butylammonium chloride (BACl), butylammonium bromide (BABr), butylammonium iodide (BAI), N,N-dimethyl-1,3-propylenediamine hydrochloride (DMePDADCl), and dodecanediamine bromide (DDDADBr).

3. The method for preparing a perovskite thin film according to claim 1, wherein: The dissolving solution is at least one of ethanol, isopropanol and methanol.

4. The method for preparing a perovskite thin film according to claim 1, wherein: The dissolving solution is coated on the lead iodide film by spin coating, with a spin coating speed of 1200-6000 rpm and a spin coating time of 20-120 seconds. After the spin coating is completed, an annealing operation is performed, with an annealing temperature of 50-150° C. and an annealing time of 5-40 minutes. Alternatively, an immersion coating method is used, in which a sample prepared with the lead iodide film is immersed in the dissolving solution for an immersion time of 0-40 minutes, and then taken out and annealed at a temperature of 50-150° C. and an annealing time of 5-40 minutes.

5. The method for preparing a perovskite thin film according to claim 1, wherein: The evaporation rate of lead iodide is controlled at 0-10A / s, the evaporation rate of cesium bromide is controlled at 0-10A / s, the evaporation rate of the organic additive is controlled at 0-10A / s, and the total evaporation time is controlled between 0 and 10000 s.

6. The method for preparing a perovskite thin film according to claim 1, wherein: By controlling the evaporation rates of different materials, the content ratio of lead iodide to cesium bromide is between 10:1 and 2:1, and the ratio of organic additives to lead iodide and cesium bromide is between 1:100 and 1:

5.

7. The method for preparing a perovskite thin film according to any one of claims 1 to 6, wherein: The preparation of the suede substrate comprises: A textured silicon substrate is provided, and a base passivation layer, a P-type base doping layer, and a first conductive layer are sequentially prepared on one side of the textured silicon substrate; and a base surface passivation layer, an N-type base doping layer, a tunneling layer, and a hole transport layer are sequentially prepared on the other side of the textured silicon substrate to obtain the textured substrate, wherein the perovskite absorption layer is formed on the hole transport layer.

8. The method for preparing a perovskite thin film according to claim 7, wherein: The perovskite thin film preparation method further includes sequentially forming a passivation layer, an electron transport layer, a buffer layer, a second conductive layer, and an anti-reflection layer on the surface of the perovskite absorption layer.

9. A stacked solar cell, prepared by the perovskite thin film preparation method according to any one of claims 1 to 8, characterized in that: The invention comprises a suede substrate; and a perovskite absorption layer, a passivation layer, an electron transport layer, a buffer layer, a second conductive layer and an anti-reflection layer which are sequentially arranged on the surface of the suede substrate.

10. The tandem solar cell according to claim 9, characterized in that: The textured substrate includes a textured crystalline silicon layer; a tunneling layer and a hole transport layer sequentially arranged on one surface of the textured crystalline silicon layer, the perovskite absorption layer is arranged on the hole transport layer; and a first conductive layer arranged on the other surface of the textured crystalline silicon layer.

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