Preparation method for perovskite thin film, and laminated solar cell

Abstract

The present invention provides a preparation method for a perovskite thin film. The preparation method comprises adding a certain proportion of a low-boiling-point solvent to a perovskite precursor solution, and using a film preparation method of hot dip coating and then annealing. The method can achieve an effect of uniformly volatilizing the solvent during the process of drying a thick wet film. Compared with a traditional method, the method can effectively reduce the organic solvent and additives remaining on a suede substrate, prevent defects from being formed within the film, and improve the quality of the perovskite thin film and the performance of a device. A laminated solar cell prepared by means of the method has a significantly reduced defect density within the film, and has a higher open-circuit voltage and a higher short-circuit current density, thereby improving the stability and photoelectric conversion efficiency of the device.

Description

A method for preparing perovskite thin film and stacked solar cell Technical Field

[0001] 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 crystalline silicon stacked solar cell. Background Art

[0002] 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.

[0003] 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.

[0004] In this regard, the use of a velvet crystalline silicon substrate is an inevitable option to further improve the performance of crystalline silicon / perovskite tandem solar cells. For example, a patent with publication number CN112151634A discloses a method for coating perovskite materials on a crystalline silicon solar cell with a velvet surface, wherein a perovskite precursor liquid is coated on the cleaned velvet crystalline silicon cell layer, and annealed to obtain a perovskite layer. However, for a velvet substrate, due to its unique substrate unevenness, it is easy to cause uneven distribution of the perovskite precursor solution. When the perovskite is formed into a film and dried on the velvet substrate, some organic solvents and additives are more likely to remain in the film, causing a large number of defects and affecting the performance of the device. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem of solvent residue easily resulting from the formation of a perovskite layer on a suede crystalline silicon solar cell in existing crystalline silicon perovskite tandem solar cells. A method for preparing a perovskite film and a tandem solar cell are proposed. A certain proportion of a low-boiling point solvent is added to the perovskite precursor solution, and a film-forming method of hot dipping followed by annealing is adopted. This method can achieve the effect of uniform solvent volatilization during the drying process of the thick wet film. Compared with traditional methods, this method can effectively reduce the residual organic solvent and additives on the suede substrate, prevent the formation of defects in the film, improve the quality of the perovskite film, and enhance device performance.

[0006] To achieve the above objectives, the present invention provides the following specific solutions.

[0007] A method for preparing a perovskite film includes the following steps.

[0008] A suede substrate is provided and heated to 60-80 degrees. The suede substrate is then completely immersed in a perovskite precursor solution. The suede substrate is then removed and tilted at an angle of 0-90 degrees to drain the residual solution for 0-600 seconds. The substrate is then annealed at a temperature of 50-150 degrees to form a perovskite absorption layer on the suede substrate.

[0009] Wherein, a low-boiling-point solvent is added to the perovskite precursor solution, and the low-boiling-point solvent includes one of γ-valerolactone, ether, acetone, dichloromethane, etc., and the solvent ratio is between 0% and 100%.

[0010] In one embodiment, the preparation of the suede substrate comprises:

[0011] 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.

[0012] 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.

[0013] In one embodiment, the perovskite thin film preparation method further includes sequentially forming a passivation layer, an electron transport layer, a buffer layer, and a second conductive layer on the surface of the perovskite absorption layer.

[0014] Specifically, the second conductive layer includes a second conductive transparent layer and a second metal electrode layer sequentially formed on the buffer layer.

[0015] The present invention also provides a laminated 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 and a second conductive layer sequentially arranged on the surface of the velvet substrate.

[0016] Specifically, the second conductive layer includes a second conductive transparent layer and a second metal electrode layer sequentially disposed on the buffer layer.

[0017] 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.

[0018] Specifically, the first conductive layer includes a first conductive transparent layer and a first metal conductive layer sequentially provided on the surface of the textured crystalline silicon layer.

[0019] 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.

[0020] The method for preparing a perovskite film provided by the present invention adds a certain proportion of a low-boiling point solvent to the perovskite precursor solution, and adopts a film-making method of hot dipping and then annealing. This method can achieve the effect of uniformly volatilizing the solvent during the process of drying the thick wet film. Compared with the traditional method, this method can effectively reduce the residual organic solvents and additives on the velvet substrate, prevent the formation of defects in the film, improve the quality of the perovskite film, and improve the device performance. Using this method, we can prepare high-quality thick perovskite films with a thickness ranging from 1 to 10 um, thereby forming complete coverage on the velvet and the substrate, and can therefore be used to prepare high-performance velvet crystalline silicon substrate crystalline silicon / perovskite stacked solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram of the steps of a method for preparing a perovskite thin film in Example 1 of the present invention.

[0022] FIG2 is a schematic diagram of the steps of a method for preparing a perovskite thin film in Comparative Example 1 of the present invention.

[0023] FIG3 is a schematic diagram of the steps of a method for preparing a perovskite thin film in Comparative Example 2 of the present invention.

[0024] FIG4 is a schematic diagram of the steps of a method for preparing a perovskite thin film in Comparative Example 3 of the present invention.

[0025] FIG5 is a schematic diagram of the structure of a stacked solar cell in Example 1 of the present invention.

[0026] 1. Velvet substrate; 2. Perovskite absorption layer; 3. Residual solvent; 4. Scraper; 20. Perovskite film layer.

[0027] 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.

[0028] 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 conductive transparent layer; 242. Second metal electrode layer. DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] Referring to FIG. 1 , an embodiment of the present invention provides a method for preparing a perovskite thin film, including the following steps.

[0032] A suede substrate 1 is provided and heated to 60-80 degrees. The suede substrate 1 is then completely immersed in a perovskite precursor solution. The suede substrate is then taken out and tilted at an angle of 0-90 degrees to drain the residual solution for 0-600 seconds. The substrate is then annealed at a temperature of 50-150 degrees to form a perovskite absorption layer 2 on the suede substrate.

[0033] In one embodiment, a low-boiling-point solvent is added to the perovskite precursor solution, and the low-boiling-point solvent includes one of γ-valerolactone, ether, acetone, dichloromethane, etc., and the solvent ratio is between 0% and 100%.

[0034] Specifically, when the velvet substrate 1 is immersed in the perovskite precursor solution, the velvet structure on its surface can well allow the perovskite precursor solution to adhere to it, and form a perovskite film layer 20 when it is taken out. The film layer is a wet film structure. After annealing treatment, the solvent evaporates and the molecules react, thereby forming the perovskite absorption layer 2.

[0035] 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 .

[0036] The B position is a metal cation, including Pb 2+ 、Sn 2+ At least one of .

[0037] The X position is a halogen anion, including F - 、Cl - Br - , I - At least one of .

[0038] The preparation of the perovskite precursor solution includes: weighing 0.5-3M perovskite powder and dissolving it in 0.5-5mL of an organic solvent, and then adding 0.5-5mL of a low-boiling point solvent additive to obtain the perovskite precursor solution.

[0039] The organic solvent includes at least one of dimethylformamide (DMF), g-butyrolactone (GBL), dimethyl sulfoxide (DMSO), and N,N-dimethylacetamide (DMA).

[0040] 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.

[0041] However, in the process of forming the perovskite absorption layer 2 using the perovskite precursor solution, due to the velvet structure on the velvet substrate 1, some residual solvent 3 will remain at the interface between the velvet substrate 1 and the perovskite absorption layer 2. If it cannot be further cleaned up, it will cause the formation of defects in the film and reduce the performance of the device.

[0042] In an embodiment of the present invention, a low-boiling-point solvent is added to the perovskite precursor solution in a certain proportion, and a film-forming method using hot dip coating followed by annealing is employed. This method achieves uniform solvent evaporation during the drying process of thick wet films. Compared to traditional methods, this method can effectively reduce residual organic solvents and additives on the suede substrate, prevent the formation of defects within the film, improve the quality of the perovskite film, and enhance device performance.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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 and a second conductive layer 24 on the surface of the perovskite absorption layer 2, and the second conductive layer 24 includes a second conductive transparent layer 241 and a second metal electrode layer 242 sequentially formed on the buffer layer 23.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 241 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 241 is formed by sputtering. The first metal electrode layer 242 is formed by evaporation. The substrate sample to be prepared is placed on a mask 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 second metal electrode layer 242.

[0061] The perovskite thin film preparation method provided in this embodiment adds a low-boiling point solvent to the perovskite precursor solution, so that the solvent evaporates more evenly on the velvet structure, with less solvent residue in the velvet structure. At the same time, the film layer structure at the interface is further improved, and the formation of defects in the film is reduced, thereby improving the performance and stability of the device.

[0062] Please refer to Figure 5. An embodiment of the present invention also provides a stacked solar cell obtained by the above-mentioned perovskite thin film preparation method, including a suede substrate 1; and a perovskite absorption layer 2, a passivation layer 21, an electron transport layer 22, a buffer layer 23 and a second conductive layer 24 arranged in sequence on the surface of the suede substrate.

[0063] Specifically, the second conductive layer 24 includes a second conductive transparent layer 241 and a second metal electrode layer 242 sequentially disposed on the buffer layer 23 .

[0064] 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 and the second conductive layer 24 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.

[0065] 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 .

[0066] The B position is a metal cation, including Pb 2+ 、Sn 2+ At least one of .

[0067] The X position is a halogen anion, including F - 、Cl - Br - , I - At least one of .

[0068] 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).

[0069] 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).

[0070] 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).

[0071] The second conductive layer 24 is composed of a second conductive transparent layer 241 and a second metal electrode layer 242, which performs the function of conducting electrons and outputting current. Specifically, the second metal electrode layer 242 is composed of at least one of silver (Ag), gold (Au), copper (Cu), aluminum (Al), and carbon (C); the second conductive transparent layer 241 is composed of at least one of indium tin oxide (ITO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO).

[0072] 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 conductive layer 101 sequentially arranged on the surface of the textured crystalline silicon layer 11.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] The present invention provides a stacked solar cell, comprising a suede substrate 1, a perovskite absorption layer 2, a passivation layer 21, an electron transport layer 22, a buffer layer 23 and a second conductive layer 24. A low-boiling-point additive is added to a perovskite precursor solution to achieve the effect of uniformly volatilizing the solvent, thereby reducing the solvent residue at the contact interface between the perovskite absorption layer 2 and the suede substrate 1, reducing defects in the film, and further improving the structure of the contact interface between the perovskite absorption layer 2 and the suede substrate 1, thereby improving the performance and stability of the device.

[0078] 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. Example

[0079] A stacked solar cell is provided, comprising 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 241, and a second metal electrode layer 242. The stacked solar cell is prepared by the following method, comprising the steps of:

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] Step 6: Weigh 1.7M perovskite powder and dissolve it in 1mL of DMF and DMSO solvents at a solvent ratio of 8:2. Then, add 0.2mL of γ-valerolactone as a low-boiling-point solvent additive to obtain a perovskite precursor solution. Heat the substrate sample prepared in the previous step to 60°C and completely immerse it in the perovskite precursor solution. Remove the substrate sample and tilt it at a 45-degree angle to drain any remaining solvent for 30 seconds. Annealing is then performed at 110°C for 20 minutes. A 5µm thick perovskite absorption layer 2 is formed on the hole transport layer 13.

[0086] 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 -4 Pa, 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.

[0087] 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.

[0088] 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 .

[0089] 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 241 is formed on the buffer layer 23 .

[0090] 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, silver is evaporated to the second conductive transparent layer 241 to obtain the second metal electrode layer 242, and finally a stacked solar cell is obtained.

[0091] Comparative Example 1

[0092] A stacked solar cell is provided, which has the same device structure as Example 1, but the difference in preparation method from Example 1 is that γ-valerolactone is not added as a low-boiling point solvent additive to the perovskite precursor solution in step 6, as shown in FIG2 .

[0093] Comparative Example 2

[0094] A stacked solar cell is provided, which has the same device structure as Example 1, but the preparation method differs from Example 1 in that a conventional method is used to prepare a perovskite absorption layer 2 in step six, and a flash evaporation method is used to prepare a perovskite precursor solution. The perovskite powder is weighed and dissolved in 1 ml of DMF and DMSO solvent in a solvent ratio of 8:2, and magnetic stirring is performed for 30 minutes. Subsequently, the sample is placed on a spin coater base, the spin coating speed is set to 1000 rpm, the spin coating time is set to 10 seconds, and the amount of perovskite precursor solution is 120 ul to coat the surface of the sample. After the spin coating is completed, the sample is placed on a flash evaporation table, the flash evaporation time is set to 30 seconds, and the flash evaporation temperature is set to 30°C. After the flash evaporation is completed, annealing treatment is performed, the annealing temperature is set to 100°C, the annealing time is 15 minutes, and the thickness is about 5 μm, to obtain a perovskite absorption layer 2; in addition, the perovskite precursor solution can also be covered on the velvet structure by scraping, spraying, printing, etc. as shown in Figure 3.

[0095] Comparative Example 3

[0096] A stacked solar cell is provided, which has the same device structure as Example 1, but the preparation method differs from Example 1 in that the traditional method is used to prepare the perovskite absorption layer 2 in step 6, and step 6 is changed to use a flash evaporation method, with a perovskite precursor solution, weighing the perovskite powder and dissolving it in 1 ml of DMF and DMSO solvent, the solvent ratio is 8:2, and magnetic stirring is performed for 30 minutes. Then, the sample is placed on the base of a spin coater, the spin coating speed is set to 3000 rpm, the spin coating time is 30 seconds, and the amount of perovskite precursor solution is 120 ul to coat the surface of the sample. After the spin coating is completed, the sample is placed on a flash evaporation table, the flash evaporation time is set to 30 seconds, the flash evaporation temperature is 30°C, and annealing is performed after the flash evaporation is completed. The annealing temperature is set to 100°C, the annealing time is 15 minutes, and the thickness is about 700 nm. In addition, the perovskite precursor solution can also be covered on the velvet structure by scraping, spraying, printing, etc., as shown in Figure 4.

[0097] The preparation methods of the above-mentioned comparative examples 3 and 4 are basically the same, and the focus is on the coverage of the perovskite film layer 20 (i.e., the wet film formed by the adhesion of the perovskite precursor liquid) on the velvet structure. In comparative example 4, the spin coating speed is fast, and the obtained perovskite film layer 20 basically covers the velvet structure and has a relatively low thickness.

[0098] A solar simulator was used to perform a standard solar intensity calibration and a 1.0 cm 2 The devices obtained in the above embodiments and comparative examples 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 retained to two decimal places. The test results are shown in the following table:

[0099] The perovskite solution with a low-boiling-point solvent undergoes two-step evaporation during film formation. 1. During the tilted film formation process, the low-boiling-point solvent slowly evaporates, removing some organic impurities dissolved in the solvent and allowing the perovskite to nucleate uniformly on the velvet surface without affecting the perovskite film formation. 2. During the annealing process, all solvent evaporates rapidly, resulting in a high-quality film.

[0100] Without the addition of a low-boiling-point solvent, the perovskite solvent evaporates rapidly during the final annealing step. This prevents the perovskite from nucleating slowly and evenly, resulting in uneven film formation. Furthermore, because the liquid-to-solid transition is so rapid, many organic impurities cannot be effectively removed by solvent evaporation, thus affecting film quality.

[0101] The present invention aims to provide a method for forming an efficient perovskite film on a velvet crystalline silicon substrate, for preparing an efficient perovskite / crystalline silicon stacked solar cell based on a velvet substrate. The conventional method for preparing perovskite films cannot form high-quality thick perovskite films on a velvet substrate. If a 5um thick film is prepared using the conventional method, a large number of defects will be formed in the film due to residual organic solvents, thereby affecting the performance of the device. By comparing the example with Comparative Example 2, it can be found that the device based on the thick perovskite film prepared by the conventional method has low efficiency, low open circuit voltage, and greater attenuation rate. The conventional method can be used to prepare high-quality thin perovskite films, but in Comparative Example 3, when the film thickness is reduced to 700nm, the perovskite film cannot completely cover the velvet crystalline silicon, thus causing the device in Comparative Example 3 to short-circuit, with a photoelectric conversion efficiency of only 3.2% and an open circuit voltage of less than 1V.

[0102] Compared with Example 1 and Comparative Example 1, we added a low-boiling point solvent additive to the hot dip coating film-forming method. The additive will evaporate first during the hot dip coating and draining process, and better remove the organic solvent and additive residues in the film. Therefore, the device prepared by this method in Example 1 has the best photoelectric conversion efficiency of 31.25%, the highest open circuit voltage of 1.99V, and the lowest attenuation rate of 0.3% when the film thickness is 5um. These high performances are all due to its lower intra-film defects. The present invention aims to provide a method for preparing a perovskite film based on a velvet crystalline silicon substrate and a crystalline silicon / perovskite stacked solar cell, a certain proportion of a low-boiling point solvent is added to the perovskite precursor solution, and a hot dip coating and then annealing film-forming method is adopted to reduce the residual organic solvent and additives on the velvet substrate, prevent the formation of defects in the film, improve the quality of the perovskite film, and improve the device performance and stability.

[0103] 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 film, characterized in that: Includes steps: A velvet substrate is provided, heated to 60-80 degrees, and then the velvet substrate is completely immersed in a perovskite precursor solution, and then the velvet substrate is taken out and tilted at an angle of 0-90 degrees to drain the residual solution for 0-600 seconds, and then annealed at a temperature of 50-150 degrees to form a perovskite absorption layer on the velvet substrate.

2. The method for preparing a perovskite thin film according to claim 1, characterized in that: The preparation of the perovskite precursor solution comprises: Weigh 0.5~3M perovskite powder and dissolve it in 0.5~5mL of organic solvent, then add 0.5~5mL of low boiling point solvent additive to obtain a perovskite precursor solution.

3. The method for preparing a perovskite thin film according to claim 1, characterized in that: A low boiling point solvent is added to the perovskite precursor solution, and the low boiling point solvent includes one of γ-valerolactone, ether, acetone, dichloromethane, etc., and the solvent ratio is between 0% and 100%.

4. The method for preparing a perovskite thin film according to any one of claims 1 to 3, characterized in that: 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.

5. The method for preparing a perovskite thin film according to claim 4, characterized in that: The first conductive layer includes a first conductive transparent layer and a first metal electrode layer which are sequentially formed on the P-type base doping layer.

6. The method for preparing a perovskite thin film according to any one of claims 1 to 3, characterized in that: The method for preparing the perovskite thin film further comprises sequentially forming a passivation layer, an electron transport layer, a buffer layer and a second conductive layer on the surface of the perovskite absorption layer.

7. The method for preparing a perovskite thin film according to claim 6, characterized in that: The second conductive layer includes a second conductive transparent layer and a second metal electrode layer sequentially formed on the buffer layer.

8. A laminated solar cell, prepared by the method for preparing a perovskite thin film according to any one of claims 1 to 7, characterized in that: The invention comprises a suede substrate; and a perovskite absorption layer, a passivation layer, an electron transport layer, a buffer layer and a second conductive layer which are sequentially arranged on the surface of the suede substrate.

9. The tandem solar cell according to claim 8, characterized in that: The textured substrate comprises 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 being arranged on the hole transport layer; and a first conductive layer arranged on the other surface of the textured crystalline silicon layer.

10. The tandem solar cell according to claim 9, characterized in that: The textured crystalline silicon layer comprises a textured silicon substrate; and a base passivation layer and a P-type base doping layer sequentially arranged on a surface of the textured silicon substrate, wherein the first conductive layer is arranged on the P-type base doping layer; A substrate surface passivation layer and an N-type substrate doping layer are sequentially prepared on the other surface of the textured silicon substrate, and the tunneling layer is arranged on the N-type substrate doping layer.

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