Three-section laminated solar cell

Abstract

The utility model provides a three-section laminated solar cell, which comprises a crystal silicon bottom cell, a perovskite middle cell and a perovskite top cell, the perovskite top cell comprises a top cell hole transport layer, a top cell perovskite absorption layer, a top cell passivation layer, a top cell electron transport layer, a top cell buffer layer, a second transparent electrode layer, a third transparent electrode layer, a second metal electrode layer and an antireflection layer. According to the perovskite top cell, the transparent electrode layers comprise the second transparent electrode layer and the third transparent electrode layer arranged on the top surface of the second transparent electrode layer, namely, a double-layer transparent electrode structure is used, the thin film interference principle is utilized, and the thickness of the third transparent electrode layer is adjusted, so that the light transmissivity of the perovskite top cell at the wave band of 600-800nm is improved, and the light transmittance of the perovskite top cell at the wave band of 600-800nm is improved. Therefore, the current matching among the perovskite top cell, the perovskite middle cell and the crystalline silicon bottom cell is improved, and the photoelectric conversion efficiency of the three-section laminated solar cell is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cells, and more specifically, relates to a three-section stacked solar cell. Background Art

[0002] Currently, perovskite / perovskite / crystalline silicon three-cell tandem solar cells are highly favored due to their high photoelectric conversion efficiency. In a perovskite / perovskite / crystalline silicon three-cell tandem solar cell, the perovskite top cell absorbs light in the range of approximately 350-600nm, the perovskite middle cell absorbs light in the range of approximately 600-800nm, and the crystalline silicon bottom cell absorbs light in the range of approximately 800-1200nm. Maximizing the efficiency of a three-cell tandem solar cell requires current matching between the perovskite top cell, the perovskite middle cell, and the crystalline silicon bottom cell. This means that the currents generated by these three cells must be as equal as possible.

[0003] However, the top transparent electrode commonly used in existing perovskite top cells is a single-layer transparent conductive oxide, whose highest light transmittance is in the band of 800-1200nm, which seriously affects the current matching between the perovskite top cell, the perovskite middle cell and the crystalline silicon bottom cell, thereby reducing the photoelectric conversion efficiency of the three-cell stacked solar cell. Utility Model Content

[0004] The purpose of the embodiments of the present application is to provide a three-cell stacked solar cell to solve the problem existing in the related art: the top transparent electrode commonly used in the perovskite top cell is a single-layer transparent conductive oxide, and its highest light transmittance band is in the 800-1200nm range, which seriously affects the current matching between the perovskite top cell, the perovskite middle cell and the crystalline silicon bottom cell, thereby reducing the photoelectric conversion efficiency of the three-cell stacked solar cell.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of the present application are:

[0006] Provided is a three-cell stacked solar cell, comprising a crystalline silicon bottom cell, a perovskite middle cell arranged on the top surface of the crystalline silicon bottom cell, and a perovskite top cell arranged on the top surface of the perovskite middle cell, wherein the perovskite top cell comprises a top cell hole transport layer arranged on the top surface of the perovskite middle cell, a top cell perovskite absorption layer arranged on the top surface of the top cell hole transport layer, a top cell passivation layer arranged on the top surface of the top cell perovskite absorption layer, a top cell electron transport layer arranged on the top surface of the top cell passivation layer, a top cell buffer layer arranged on the top surface of the top cell electron transport layer, a second transparent electrode layer arranged on the top surface of the top cell buffer layer, a third transparent electrode layer arranged on the top surface of the second transparent electrode layer, a second metal electrode layer arranged on the top surface of the third transparent electrode layer, and an anti-reflection layer arranged on the top surface of the second metal electrode layer.

[0007] In one embodiment, the thickness of the third transparent electrode layer is greater than or equal to the thickness of the second transparent electrode layer.

[0008] In one embodiment, the thickness of the third transparent electrode layer is in the range of 40-200 nm, and the thickness of the second transparent electrode layer is in the range of 1-80 nm.

[0009] In one embodiment, the thickness of the third transparent electrode layer is 80 nm.

[0010] In one embodiment, the crystalline silicon bottom cell includes a silicon substrate, a base passivation layer provided on the bottom surface of the silicon substrate, a P-type base doping layer provided on the bottom surface of the base passivation layer, a first transparent electrode layer provided on the bottom surface of the P-type base doping layer, a first metal electrode layer provided on the first transparent electrode layer, a base surface passivation layer provided on the top surface of the silicon substrate, an N-type base doping layer provided on the top surface of the base surface passivation layer, and a first tunneling layer provided on the top surface of the N-type base doping layer; the bottom surface of the perovskite cell is provided on the top surface of the first tunneling layer.

[0011] In one embodiment, the perovskite mid-battery includes a mid-battery hole transport layer arranged on the top surface of the first tunneling layer, a mid-battery perovskite absorption layer arranged on the top surface of the mid-battery hole transport layer, a mid-battery passivation layer arranged on the top surface of the mid-battery perovskite absorption layer, a mid-battery electron transport layer arranged on the top surface of the mid-battery passivation layer, a mid-battery buffer layer arranged on the top surface of the mid-battery electron transport layer and a second tunneling layer arranged on the top surface of the mid-battery buffer layer; the top battery hole transport layer is arranged on the top surface of the second tunneling layer.

[0012] In one embodiment, the thickness of the mid-cell hole transport layer is in the range of 1-600 nm, the thickness of the mid-cell perovskite absorption layer is in the range of 1-600 nm, and the thickness of the mid-cell electron transport layer is in the range of 1-600 nm.

[0013] In one embodiment, the thickness of the intermediate battery buffer layer is in the range of 1-30 nm.

[0014] In one embodiment, the thickness range of the top battery hole transport layer is 1-600 nm, the thickness range of the top battery perovskite absorption layer is 1-600 nm, the thickness range of the top battery electron transport layer is 1-600 nm, the thickness range of the second metal electrode layer is 1-600 nm, and the thickness range of the anti-reflection layer is 1-600 nm.

[0015] In one embodiment, the top cell buffer layer has a thickness in the range of 1-30 nm.

[0016] The three-cell stacked solar cell provided in the embodiment of the present application has at least the following beneficial effects: the present application optimizes the structure of the transparent electrode layer in the traditional perovskite top cell, and sets the transparent electrode layer as a second transparent electrode layer and a third transparent electrode layer arranged on the top surface of the second transparent electrode layer, that is, a double-layer transparent electrode structure is used, and the thin film interference principle is utilized and the thickness of the third transparent electrode layer is adjusted, so that the light transmittance of the perovskite top cell in the band of 600-800nm is improved, thereby improving the current matching between the perovskite top cell, the perovskite middle cell and the crystalline silicon bottom cell, which helps to improve the photoelectric conversion efficiency of the three-cell stacked solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 Schematic diagram of the structure of a traditional three-section stacked solar cell;

[0019] Figure 2 A schematic diagram of the structure of a three-section tandem solar cell provided in an embodiment of the present application;

[0020] Figure 3 A graph showing the relationship between light transmittance and light wavelength for the three-section stacked solar cell provided in Examples 1-4.

[0021] Among them, the main marks of the drawings in the figure are:

[0022] 1. Crystalline silicon bottom cell; 11. First metal electrode layer; 12. First transparent electrode layer; 13. P-type base doping layer; 14. Base passivation layer; 15. Silicon substrate; 16. Base surface passivation layer; 17. N-type base doping layer; 18. First tunneling layer;

[0023] 2. Perovskite midcell; 21. Midcell hole transport layer; 22. Midcell perovskite absorption layer; 23. Midcell passivation layer; 24. Midcell electron transport layer; 25. Midcell buffer layer; 26. Second tunneling layer;

[0024] 3. Perovskite top cell; 31. Top cell hole transport layer; 32. Top cell perovskite absorption layer; 33. Top cell passivation layer; 34. Top cell electron transport layer; 35. Top cell buffer layer; 36. Second transparent electrode layer; 37. Third transparent electrode layer; 38. Second metal electrode layer; 39. Anti-reflection layer. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0026] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0027] In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0028] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, when the phrases "in one embodiment" or "in some embodiments" appear in various places throughout this specification, not all references are to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0029] In order to solve the problem of poor current matching between the perovskite top cell 3, the perovskite middle cell 2, and the crystalline silicon bottom cell 1 in a traditional perovskite / perovskite / crystalline silicon three-cell tandem solar cell, which affects the photoelectric conversion efficiency of the three-cell tandem solar cell, the present invention provides a three-cell tandem solar cell to solve the above problem.

[0030] See also Figure 2The three-cell tandem solar cell provided in an embodiment of the present application is now described. The three-cell tandem solar cell includes a crystalline silicon bottom cell 1, a perovskite middle cell 2, and a perovskite top cell 3. The perovskite middle cell 2 can be disposed between the crystalline silicon bottom cell 1 and the perovskite top cell 3. Specifically, the perovskite middle cell 2 is disposed on top of the crystalline silicon bottom cell 1, and the perovskite top cell 3 is disposed on top of the perovskite middle cell 2. Among them, the crystalline silicon bottom cell 1 includes a silicon substrate 15, a base passivation layer 14 provided on the bottom surface of the silicon substrate 15, a P-type base doping layer 13 provided on the bottom surface of the base passivation layer 14, a first transparent electrode layer 12 provided on the bottom surface of the P-type base doping layer 13, a first metal electrode layer 11 provided on the bottom surface of the first transparent electrode layer 12, a base surface passivation layer 16 provided on the top surface of the silicon substrate 15, an N-type base doping layer 17 provided on the top surface of the base surface passivation layer 16, and a first tunneling layer 18 provided on the top surface of the N-type base doping layer 17. The perovskite mid-cell 2 includes a mid-cell hole transport layer 21 arranged on the top surface of the first tunneling layer 18, a mid-cell perovskite absorption layer 22 arranged on the top surface of the mid-cell hole transport layer 21, a mid-cell passivation layer 23 arranged on the top surface of the mid-cell perovskite absorption layer 22, a mid-cell electron transport layer 24 arranged on the top surface of the mid-cell passivation layer 23, a mid-cell buffer layer 25 arranged on the top surface of the mid-cell electron transport layer 24, and a second tunneling layer 26 arranged on the top surface of the mid-cell buffer layer 25. The perovskite top cell 3 includes a top cell hole transport layer 31 arranged on the top surface of the second tunneling layer 26, a top cell perovskite absorption layer 32 arranged on the top surface of the top cell hole transport layer 31, a top cell passivation layer 33 arranged on the top surface of the top cell perovskite absorption layer 32, a top cell electron transport layer 34 arranged on the top surface of the top cell passivation layer 33, a top cell buffer layer 35 arranged on the top surface of the top cell electron transport layer 34, a second transparent electrode layer 36 arranged on the top surface of the top cell buffer layer 35, a third transparent electrode layer 37 arranged on the top surface of the second transparent electrode layer 36, a second metal electrode layer 38 arranged on the top surface of the third transparent electrode layer 37, and an anti-reflection layer 39 arranged on the top surface of the second metal electrode layer 38.

[0031] See also Figure 1For comparative analysis, the present invention also provides a conventional three-cell tandem solar cell, whose specific structure, from bottom to top, comprises a first metal electrode layer 11, a first transparent electrode layer 12, a P-type base doping layer 13, a base passivation layer 14, a silicon substrate 15, a base surface passivation layer 16, an N-type base doping layer 17, a first tunneling layer 18, a middle cell hole transport layer 21, a middle cell perovskite absorber layer 22, a middle cell passivation layer 23, a middle cell electron transport layer 24, a middle cell buffer layer 25, a second tunneling layer 26, a top cell hole transport layer 31, a top cell perovskite absorber layer 32, a top cell passivation layer 33, a top cell electron transport layer 34, a top cell buffer layer 35, a second transparent electrode layer 36, a second metal electrode layer 38, and an anti-reflection layer 39. The structure of the three-cell tandem solar cell provided in the present invention is an improvement on the structure of the conventional three-cell tandem solar cell. The preparation methods of the conventional three-cell tandem solar cell and the three-cell tandem solar cell provided in the present invention are now described in detail. Specifically, the specific steps for making a traditional three-section tandem solar cell are as follows:

[0032] Step 1: a base passivation layer 14 and a P-type base doping layer 13 are sequentially formed on the bottom surface of the silicon substrate 15 , and a base surface passivation layer 16 and an N-type base doping layer 17 are sequentially formed on the surface of the silicon substrate 15 .

[0033] Step 2: Prepare a first transparent electrode layer 12 on the bottom surface of the P-type base doped layer 13. Optionally, magnetron sputtering is performed by placing the sample in a magnetron sputtering device, setting an ITO (Indium Tin Oxide) target, and controlling the power between 50 and 200 W. Specifically, in this embodiment, the controlled power is 60 W, the operation time is 1.5 hours, and the thickness of the first transparent electrode layer 12 is 100 nm.

[0034] Step 3: Prepare the first metal electrode layer 11 on the bottom surface of the first transparent electrode layer 12. Optionally, the prepared sample is placed on a mask by evaporation and placed in the chamber of an evaporation machine. The evaporation vacuum is 5×10 -5 -2×10 -4 Pa, the evaporation temperature is 500-2000 ° C, and the evaporation rate is 0.1-5 Å / S. Specifically, in the embodiment of the present application, the evaporation vacuum is 2×10 -4 Pa, the evaporation voltage is adjusted to the evaporation temperature, the evaporation rate is controlled at 2.5Å / S, and silver is evaporated onto the layer film. The thickness of the first metal electrode layer 11 is 200nm.

[0035] Step 4: Form a first tunneling layer 18 on the surface of the N-type base doped layer 17. Optionally, the first tunneling layer 18 can be formed using atomic force microdeposition, magnetron sputtering, or a wet chemical method. Specifically, in this embodiment of the application, magnetron sputtering can be used. After placing the sample on a mask, it is placed in a magnetron sputtering device with a controlled power of 60 W and a run time of 1 hour. The thickness of the first tunneling layer 18 is 40 nm.

[0036] Step 5: Prepare a middle battery hole transport layer 21 on the surface of the first tunneling layer 18. The middle battery hole transport layer 21 can be at least one of poly (4-phenyl) (2,4,6-trimethylphenyl) amine) (PTAA), poly-3 hexylthiophene (P3HT), nickel oxide (NiOx), molybdenum trioxide (MoO3), cuprous iodide (CuI), and cuprous thiocyanate (CuSCN).

[0037] Alternatively, the hole transport layer dispersion can be evenly coated on the surface of the first tunneling layer 18 by spin coating at a speed of 1000-5000 rpm for 10-100 seconds. After the spin coating is completed, an annealing operation is performed at a temperature of 300-600° C. for 10-50 minutes.

[0038] Optionally, a magnetron sputtering method may be used, and the prepared sample is placed in a magnetron sputtering device with a controlled power of 30-90W.

[0039] Specifically, the present embodiment utilizes a spin coating method. The sample is treated in a UV-Ozone cleaner for 15 minutes. A hole transport layer dispersion is prepared by dissolving 0.05 mol of NiOx powder in 1 ml of ultrapure water and ultrasonically vibrating for 20 minutes. The hole transport layer dispersion is evenly applied to the surface of the sample. The spin coating speed is set to 2000 rpm, the spin coating time is 40 seconds, and the solution volume is 100 μl. After spin coating, an annealing operation is performed at 450°C for 30 minutes. The thickness of the hole transport layer 21 of the intermediate cell is 20 nm.

[0040] Step 6: Prepare the middle cell perovskite absorption layer 22 on the surface of the middle cell hole transport layer 21 .

[0041] Optionally, a spin coating method can be used to prepare a perovskite precursor solution, and the perovskite precursor solution is evenly coated on the surface of the middle battery hole transport layer 21, and then an anti-solvent is used for dynamic spin coating, the spin coating speed is 1200-6000 rpm, the spin coating time is 20-120s, and the anti-solvent titration time is 10-50s after the start of the speed. After the spin coating is completed, an annealing operation is performed, the annealing temperature is 50-150°C, and the annealing time is 5-40min. The dissolving solvent of the perovskite precursor solution includes at least one of dimethylformamide (DMF), G-butyrolactone (GBL), dimethyl sulfoxide (DMSO) and N,N-dimethylacetamide (DMA), and the solvent ratio is between 0-3:10-7. The anti-solvent may include at least one of toluene (Tol), chlorobenzene (CB), and ethyl acetate (EA).

[0042] Alternatively, a flash evaporation method can be used to prepare a perovskite precursor solution, which is then evenly coated on the surface of the middle cell hole transport layer 21 at a spin coating speed of 1000-6000 rpm for 20-120 seconds. After spin coating, a flash evaporation operation is performed for 10-60 seconds at a flash evaporation temperature of 0-100°C. After flash evaporation, an annealing treatment is performed at a temperature of 50-150°C for 5-40 minutes.

[0043] The perovskite precursor solution can be an ABX3 structure perovskite, which is adjusted by stoichiometric ratio and dissolved in an organic solvent with a concentration between 1.5-2M. In the ABX3 structure perovskite, the A position is an organic cation, including CH3NH3 + (MA + ), NH2CH=NH2 + (FA + ), CH3CH2NH3 + or Cs + At least one of; B position is a metal cation, including Pb 2 + 、Sn 2+ At least one of; X is a halogen anion, including F - 、Cl - Br - , I - At least one of .

[0044] Specifically, the flash evaporation method can be used to prepare the mid-cell perovskite absorber layer 22 in the present embodiment. Specifically, a perovskite precursor solution is prepared. A 1.52 eV bandgap perovskite powder is weighed and dissolved in 1 ml of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) in a solvent ratio of 8:2. The mixture is magnetically stirred for 30 minutes. The sample is then placed on a spin coater base, with the spin coating speed set to 3500 rpm and the spin coating time set to 30 seconds. A volume of 120 μl of the perovskite precursor solution is applied to the sample surface. After spin coating, the sample is placed on a flash evaporation table, with the flash evaporation time set to 30 seconds and the flash evaporation temperature set to 30°C. After the flash evaporation, the sample is annealed at 100°C for 15 minutes. The thickness of the mid-cell perovskite absorber layer 22 is 500 nm.

[0045] Step 7: Prepare a mid-cell passivation layer 23 on the surface of the mid-cell perovskite absorber layer 22. The mid-cell passivation layer 23 may be propylenediamine iodide, 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); or magnesium fluoride, including but not limited to at least one of lithium fluoride (LiF) and sodium fluoride (NaF).

[0046] Optionally, propylene diamine iodide can be evaporated onto the surface of the perovskite absorption layer 22 of the above-mentioned middle battery by evaporation method, and the evaporation vacuum degree is 1-5×10 -4 Pa, the evaporation temperature range is 50-400℃, the evaporation rate range is 0.05-1Å / s. After the evaporation is completed, the annealing operation is performed, the annealing temperature range is 0-150℃, and the annealing time range is 0-30min.

[0047] Alternatively, a spin coating method can be used to prepare a passivation layer dispersion and evenly coat the surface of the middle cell perovskite absorption layer 22. Propylene diamine iodine is dissolved in an organic solvent including but not limited to methanol, ethanol, or isopropanol, ultrasonically dissolved, and spin-coated. The concentration of propylene diamine iodine is 0.1-6 mg / ml, the ultrasonication time is 0-30 minutes, the spin coating speed is 1000-7000 rpm, and the spin coating time is 20-120 seconds. After the spin coating is completed, an annealing operation is performed at an annealing temperature of 40-160°C and an annealing time of 5-40 minutes.

[0048] Optionally, the passivation layer dispersion can be sprayed onto the surface of the middle cell perovskite absorption layer 22 by spraying at a rate of 0-100 cm / s. After spraying, an annealing operation is performed at a temperature of 20-170° C. for a time of 0-30 min.

[0049] Specifically, the embodiment of the present application adopts the evaporation method, weighing 3 mg of propylene diamine iodine and placing it in a crucible, placing the sample on the mask, and placing it in the evaporation chamber. The vacuum degree of the evaporation is 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 middle battery perovskite absorption layer 22. After the evaporation is completed, annealing operation is performed. The annealing temperature range is 100°C, the annealing time is 8 minutes, and the thickness of the middle battery passivation layer 23 is 4nm.

[0050] Step 8: Prepare the middle battery electron transport layer 24 on the surface of the middle battery passivation layer 23. The middle battery electron transport layer 24 is 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).

[0051] Optionally, the electron transport layer dispersion can be evenly coated on the surface of the middle battery passivation layer 23 by spin coating, with a spin coating speed of 500-4000 rpm and a spin coating time of 10-80 s.

[0052] Optionally, the electron transport layer material can be evaporated to the surface of the middle battery passivation layer 23 by evaporation method, and the evaporation vacuum range is 5×10 -5 -5×10 -4 Pa, the evaporation temperature range is 100-400℃, and the evaporation rate range is 0.05-1Å / S.

[0053] Specifically, the embodiment of the present application can adopt the evaporation method, place the sample on the mask, put it into the evaporation chamber, and wait for the evaporation vacuum degree to be 1×10 -4 Pa, the evaporation voltage was adjusted to the evaporation temperature, and the evaporation rate was controlled at 0.1-0.15Å / S. 60 The thickness of the middle battery electron transport layer 24 is 20 nm after evaporation onto the film.

[0054] Step 9: Prepare a mid-cell buffer layer 25 on the surface of the mid-cell electron transport layer 24. The mid-cell buffer layer 25 is made of at least one of zinc oxide (ZnO), tin dioxide (SnO2), and titanium dioxide (TiO2). The thickness of the mid-cell buffer layer 25 can range from 1 to 30 nm.

[0055] Alternatively, the electron transport layer material can be deposited onto the surface of the electron transport layer 24 of the middle battery using an atomic deposition method, with a deposition vacuum of 0-1×10 4 Pa, the deposition pipe temperature is between 50-150°C, and the deposition chamber temperature is 40-150°C.

[0056] Optionally, the electron transport layer modification layer material can be evaporated onto the surface of the electron transport layer 24 of the middle battery by evaporation method, and the evaporation vacuum degree is 6×10 -5 -4×10 -4 Pa, the evaporation temperature is 100-500℃, and the evaporation rate is 0.05-1Å / S.

[0057] Specifically, the embodiment of the present application can adopt the atomic accumulation deposition method, and the vacuum degree of the atomic accumulation deposition equipment is set to 0.5×10 4 Pa, the deposition pipeline temperature is between 60°C, the deposition chamber temperature is 70°C, SnO2 is evaporated onto the layer film, and the thickness of the middle battery buffer layer 25 is 15nm.

[0058] Step 10: Form a second tunneling layer 26 on the surface of the middle cell buffer layer 25. Optionally, the second tunneling layer 26 can be formed using atomic force microdeposition, magnetron sputtering, or wet chemical methods. Specifically, in this embodiment of the application, magnetron sputtering is used. The sample is placed on a mask and then in a magnetron sputtering device. The control power is 60W, the operation time is 1 hour, and the thickness of the second tunneling layer 26 is 40nm.

[0059] Step 11: Prepare a top cell hole transport layer 31 on the surface of the second tunneling layer 26. The top cell hole transport layer 31 can be made of at least one of poly(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA), poly-3-hexylthiophene (P3HT), nickel oxide (NiOx), molybdenum trioxide (MoO3), cuprous iodide (CuI), and cuprous thiocyanate (CuSCN). The preparation method for the top cell hole transport layer 31 is the same as that for the middle cell hole transport layer 21 in Step 5 and is not further described here.

[0060] Specifically, the present embodiment utilizes a spin coating method. The sample is treated in a UV-Ozone cleaner for 15 minutes. A hole transport layer dispersion is prepared by dissolving 0.05 mol of NiOx powder in 1 ml of ultrapure water, followed by ultrasonic vibration for 20 minutes. The hole transport layer dispersion is evenly applied to the surface of the sample at a spin coating speed of 2000 rpm, a spin coating time of 40 seconds, and a solution volume of 100 μl. After spin coating, an annealing operation is performed at 450°C for 30 minutes. The thickness of the top cell hole transport layer 31 is 20 nm.

[0061] Step 12: Prepare a top cell perovskite absorption layer 32 on the surface of the top cell hole transport layer 31. The preparation method of the top cell perovskite absorption layer 32 can be the same as the preparation method of the middle cell perovskite absorption layer 22 in step 6, and will not be repeated here.

[0062] Specifically, the flash evaporation method can be used to prepare the top cell perovskite absorption layer 32 in the embodiment of the present application. Specifically, a perovskite precursor solution is prepared, and 2.05eV bandgap perovskite powder is weighed and dissolved in 1ml of DMF and DMSO solvent in a solvent ratio of 8:2. The solution is magnetically stirred for 30 minutes. The sample is then placed on the base of a spin coater, and the spin coating speed is set to 3500rpm and the spin coating time is set to 30s. The amount of perovskite precursor solution is 120ul, and it is applied to the surface of the sample. After the spin coating is completed, the sample is placed on the flash evaporation table, and the flash evaporation time is set to 30s and the flash evaporation temperature is set to 30°C. After the flash evaporation is completed, an annealing treatment is performed at an annealing temperature of 100°C and an annealing time of 15 minutes. The thickness of the top cell perovskite absorption layer 32 is 500nm.

[0063] Step 13: Prepare a top cell passivation layer 33 on the surface of the top cell perovskite absorber layer 32. The top cell passivation layer 33 can be made of propylenediamine iodide, 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). It can also be made of magnesium fluoride, including but not limited to at least one of lithium fluoride (LiF) and sodium fluoride (NaF). The preparation method for this top cell passivation layer 33 is the same as the preparation method for the middle cell passivation layer 23 in Step 7 and is not further described here.

[0064] Specifically, the embodiment of the present application adopts the evaporation method, weighing 3 mg of propylene diamine iodine and placing it in a crucible, placing the sample on the mask, and placing it in the evaporation chamber. The vacuum degree of the evaporation is 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 top cell perovskite absorption layer 32. After the evaporation is completed, annealing operation is performed. The annealing temperature range is 100°C, the annealing time is 8 minutes, and the thickness of the top cell passivation layer 33 is 4nm.

[0065] Step 14: Prepare the top battery electron transport layer 34 on the surface of the top battery passivation layer 33. The top battery electron transport layer 34 is 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). The preparation method of the top cell electron transport layer 34 can be the same as the preparation method of the middle cell electron transport layer 24 in step eight, and will not be repeated here.

[0066] Specifically, the embodiment of the present application can adopt the evaporation method, place the sample on the mask, put it into the evaporation chamber, and wait for the evaporation vacuum degree to be 1×10 -4 Pa, the evaporation voltage was adjusted to the evaporation temperature, and the evaporation rate was controlled at 0.1-0.15Å / S. 60 The top cell electron transport layer 34 is evaporated onto the film to a thickness of 20 nm.

[0067] Step 15: Prepare a top cell buffer layer 35 on the surface of the top cell electron transport layer 34. The top cell buffer layer 35 is made of at least one of zinc oxide (ZnO), tin dioxide (SnO2), or titanium dioxide (TiO2). The thickness of the middle cell buffer layer 25 can range from 1 to 30 nm. The preparation method for the top cell buffer layer 35 is the same as that for the middle cell buffer layer 25 in Step 9 and is not further described here.

[0068] Specifically, the embodiment of the present application can adopt the atomic accumulation deposition method, and the vacuum degree of the atomic accumulation deposition equipment is set to 0.5×10 4 Pa, the deposition channel temperature is between 60°C, the deposition chamber temperature is 70°C, SnO2 is evaporated onto the layer film, and the thickness of the top battery buffer layer 35 is 15nm.

[0069] Step 16: Prepare a second transparent electrode layer 36 on the surface of the top battery buffer layer 35. Alternatively, the transparent electrode material can be sputtered onto the surface of the top battery buffer layer 35 by magnetron sputtering, with a controlled power of 30-200W. Alternatively, the transparent electrode material can be evaporated onto the surface of the top battery buffer layer 35 by evaporation, with a vacuum of 1×10 -5 -5×10 -4 Pa, the evaporation temperature is 1000-2000℃, and the evaporation rate is 0.05-3Å / S.

[0070] Specifically, the embodiment of the present application can adopt a magnetron sputtering method, which is similar to the preparation method of preparing the first transparent electrode layer 12 in step 2, setting an IZO (Indium Zinc Oxide) target material, controlling the power to 50 W, the operating time to 1 hour, and the thickness of the second transparent electrode layer 36 to 40 nm.

[0071] Step 17: Form a second metal electrode layer 38 on the surface of the second transparent electrode layer 36. The process is similar to that for the first metal electrode layer 11, except that the mask is different. The thickness of the second metal electrode layer 38 is 100 nm. The second metal electrode layer 38 is made of at least one of silver (Ag), gold (Au), copper (Cu), aluminum (Al), and carbon (C).

[0072] Step 18: Prepare an anti-reflection layer 39 on the surface of the second metal electrode layer 38. Optionally, this can be prepared by magnetron sputtering or evaporation. Specifically, the embodiment of the present application uses evaporation, controlling the evaporation rate at 2 Å / s to deposit magnesium fluoride onto the film. The thickness of the anti-reflection layer 39 is 100 nm. The anti-reflection layer 39 can be at least one of magnesium fluoride, lithium fluoride (LiF), sodium fluoride (NaF), and silicon oxide (SiO2).

[0073] The first transparent electrode layer 12 and the second transparent electrode layer 36 are made of at least one of indium tin oxide (ITO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO).

[0074] Among them, the thickness range of the middle cell hole transport layer 21 is 1-600nm, the thickness range of the middle cell perovskite absorber layer 22 is 1-600nm, the thickness range of the middle cell electron transport layer 24 is 1-600nm, and the thickness range of the middle cell buffer layer 25 is 1-30nm. The thickness range of the top cell hole transport layer 31 is 1-600nm, the thickness range of the top cell perovskite absorber layer 32 is 1-600nm, the thickness range of the top cell electron transport layer 34 is 1-600nm, the thickness range of the second metal electrode layer 38 is 1-600nm, the thickness range of the anti-reflection layer 39 is 1-600nm, and the thickness range of the top cell buffer layer 35 is 1-30nm.

[0075] In order to verify the performance of the traditional three-section stacked solar cell and the three-section stacked solar cell provided in the embodiments of this application, this application provides four groups of experiments for comparative demonstration, namely Example 1, Example 2, Example 3 and Example 4.

[0076] Example 1 is a traditional three-section stacked solar cell, which is prepared by the above steps 1 to 18.

[0077] Example 2 is a three-section stacked solar cell provided in an embodiment of the present application. The difference between its preparation method and the preparation method of the traditional three-section stacked solar cell provided in the above-mentioned Example 1 is that: a preparation step of preparing the third transparent electrode layer 37 is added between step sixteen and step seventeen. Specifically, similar to the preparation method of preparing the first transparent electrode layer 12 in step two, an IZO target material is set, the control power is 50W, the operating time is 1h, and the thickness of the third transparent electrode layer 37 is 40nm.

[0078] Example 3 is a three-section stacked solar cell provided in an embodiment of the present application. The difference between its preparation method and the preparation method of the traditional three-section stacked solar cell provided in the above-mentioned Example 1 is that: a preparation step of preparing the third transparent electrode layer 37 is added between step sixteen and step seventeen. Specifically, similar to the preparation method for preparing the first transparent electrode layer 12 in step two, an IZO target material is set, the control power is 50W, the operating time is 2h, and the thickness of the third transparent electrode layer 37 is 80nm.

[0079] Example 4 is a three-section stacked solar cell provided in an embodiment of the present application. The difference between its preparation method and the preparation method of the traditional three-section stacked solar cell provided in the above-mentioned Example 1 is that: a preparation step of preparing the third transparent electrode layer 37 is added between step sixteen and step seventeen. Specifically, similar to the preparation method of preparing the first transparent electrode layer 12 in step two, an IZO target material is set, the control power is 50W, the operating time is 3h, and the thickness of the third transparent electrode layer 37 is 120nm.

[0080] In one embodiment, the thickness of the third transparent electrode layer 37 is greater than or equal to the thickness of the second transparent electrode layer 36. The thickness of the third transparent electrode layer 37 is in the range of 40-200 nm, and the thickness of the second transparent electrode layer 36 is in the range of 1-80 nm.

[0081] See also Figure 3 The calculated relationship between the light transmittance and light wavelength of the three-section stacked solar cells provided in Examples 1-4 is shown in the following table.

[0082] Examples Light transmittance 350-600nm (%) Light transmittance 600-800nm(%) Light transmittance 800-1200nm(%) Example 1 79.62 91.06 96.15 Example 2 79.72 88.40 94.49 Example 3 79.83 97.74 91.56 Example 4 79.93 97.43 89.71

[0083] Four groups of samples were subjected to comparative experiments. A standard solar intensity calibration was performed using a solar simulator. 2 A three-cell stacked solar cell was subjected to a long-term IV test with the starting voltage set to 3.2V, the cut-off voltage set to 0V, and the range set to 100mA. The test results are shown in the following table.

[0084] Device Open circuit voltage (V) <![CDATA[Short-circuit current (mA / cm 2 )]]> Fill Factor Photoelectric conversion efficiency (%) Example 1 3.12 10.32 0.81 26.08 Example 2 3.12 10.15 0.81 25.65 Example 3 3.13 11.46 0.81 29.05 Example 4 3.13 11.31 0.81 28.67

[0085] From the above table we can see that:

[0086] 1. The present application optimizes the structure of the transparent electrode layer in the traditional perovskite top cell 3, and sets the transparent electrode layer as a second transparent electrode layer 36 and a third transparent electrode layer 37 provided on the top surface of the second transparent electrode layer 36, that is, a double-layer transparent electrode structure is used. By utilizing the thin film interference principle and adjusting the thickness of the third transparent electrode layer 37, the light transmittance of the perovskite top cell 3 in the band of 600-800nm is improved, thereby improving the current matching between the perovskite top cell 3, the perovskite middle cell 2 and the crystalline silicon bottom cell 1, which helps to improve the photoelectric conversion efficiency of the three-cell stacked solar cell.

[0087] 2. The thickness of the third transparent electrode layer 37 and the thickness of the second transparent electrode layer 36 in Example 2 are both 40 nm. This thickness cannot achieve the effect of thin-film interference, so its light transmittance at 600-800 nm is actually lower than that in Example 1. This results in the three-section stacked solar cell provided in Example 2 having lower short-circuit current and photoelectric conversion efficiency.

[0088] 3. The thickness of the third transparent electrode layer 37 in Examples 3 and 4 is greater than that of the second transparent electrode layer 36. The light transmittance of both examples in the 600-800 nm band is significantly increased compared to that in Example 1, approaching 100. The three-section tandem solar cells provided by Examples 3 and 4 have higher short-circuit currents and photoelectric conversion efficiencies. The three-section tandem solar cell achieves optimal performance when the thickness of the third transparent electrode layer 37 is 80 nm.

[0089] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A three-cell tandem solar cell comprising a crystalline silicon bottom cell, a perovskite middle cell disposed on top of the crystalline silicon bottom cell, and a perovskite top cell disposed on top of the perovskite middle cell, characterized in that: The perovskite top cell includes a top cell hole transport layer arranged on the top surface of the perovskite cell, a top cell perovskite absorption layer arranged on the top surface of the top cell hole transport layer, a top cell passivation layer arranged on the top surface of the top cell perovskite absorption layer, a top cell electron transport layer arranged on the top surface of the top cell passivation layer, a top cell buffer layer arranged on the top surface of the top cell electron transport layer, a second transparent electrode layer arranged on the top surface of the top cell buffer layer, a third transparent electrode layer arranged on the top surface of the second transparent electrode layer, a second metal electrode layer arranged on the top surface of the third transparent electrode layer, and an anti-reflection layer arranged on the top surface of the second metal electrode layer.

2. The three-section tandem solar cell according to claim 1, wherein: The thickness of the third transparent electrode layer is greater than or equal to the thickness of the second transparent electrode layer.

3. The three-section tandem solar cell according to claim 2, wherein: The thickness of the third transparent electrode layer is in the range of 40-200 nm, and the thickness of the second transparent electrode layer is in the range of 1-80 nm.

4. The three-section tandem solar cell according to claim 3, wherein: The thickness of the third transparent electrode layer is 80 nm.

5. The three-section tandem solar cell according to claim 1, wherein: The crystalline silicon bottom cell includes a silicon substrate, a base passivation layer arranged on the bottom surface of the silicon substrate, a P-type base doping layer arranged on the bottom surface of the base passivation layer, a first transparent electrode layer arranged on the bottom surface of the P-type base doping layer, a first metal electrode layer arranged on the first transparent electrode layer, a base surface passivation layer arranged on the top surface of the silicon substrate, an N-type base doping layer arranged on the top surface of the base surface passivation layer, and a first tunneling layer arranged on the top surface of the N-type base doping layer; the bottom surface of the perovskite cell is arranged on the top surface of the first tunneling layer.

6. The three-section tandem solar cell according to claim 5, wherein: The perovskite mid-battery includes a mid-battery hole transport layer arranged on the top surface of the first tunneling layer, a mid-battery perovskite absorption layer arranged on the top surface of the mid-battery hole transport layer, a mid-battery passivation layer arranged on the top surface of the mid-battery perovskite absorption layer, a mid-battery electron transport layer arranged on the top surface of the mid-battery passivation layer, a mid-battery buffer layer arranged on the top surface of the mid-battery electron transport layer and a second tunneling layer arranged on the top surface of the mid-battery buffer layer; the top battery hole transport layer is arranged on the top surface of the second tunneling layer.

7. The three-section tandem solar cell according to claim 6, wherein: The thickness of the middle battery hole transport layer is in the range of 1-600 nm, the thickness of the middle battery perovskite absorption layer is in the range of 1-600 nm, and the thickness of the middle battery electron transport layer is in the range of 1-600 nm.

8. The three-section tandem solar cell according to claim 6, wherein: The thickness of the intermediate battery buffer layer is in the range of 1-30 nm.

9. The three-section tandem solar cell according to any one of claims 1 to 8, wherein: The thickness range of the top battery hole transport layer is 1-600nm, the thickness range of the top battery perovskite absorption layer is 1-600nm, the thickness range of the top battery electron transport layer is 1-600nm, the thickness range of the second metal electrode layer is 1-600nm, and the thickness range of the anti-reflection layer is 1-600nm.

10. The three-section tandem solar cell according to any one of claims 1 to 8, wherein: The thickness of the top cell buffer layer is in the range of 1-30 nm.

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