Perovskite / crystalline silicon laminated solar cell and preparation method thereof

Abstract

The invention provides a perovskite / crystalline silicon laminated solar cell and a preparation method thereof, and belongs to the technical field of solar cells. Comprising a silicon bottom cell and a perovskite top cell which are sequentially stacked from bottom to top. The perovskite top cell comprises a hole transport layer, an organic absorption layer, a perovskite absorption layer, a passivation layer, an electron transport layer, a third transparent electrode layer, a second metal electrode layer and an anti-reflection layer. Through the organic donor-acceptor heterojunction integrated at the perovskite end, the short-circuit current is adaptively adjusted under the intensities of different near-infrared bands in a standard spectrum, so that the short-circuit current is matched with the silicon current, and the efficiency and the interval generating capacity of the laminated solar cell are maximized.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a perovskite / crystalline silicon tandem solar cell that adapts to changes in the solar spectrum and its fabrication method. Background Technology

[0002] With the continued growth in global demand for clean energy, the efficiency and cost reduction of solar cell technology have become research hotspots. Perovskite / crystalline silicon tandem solar cells combine perovskite and monocrystalline silicon materials in layers, forming a complementary photoelectric conversion system. Its core advantage lies in the synergistic expansion of the spectral response range: the perovskite thin film has an extremely high absorption coefficient for short-wavelength light (300-700 nm) in the solar spectrum, capturing most of the short-wavelength energy within a sub-micron thickness; while the crystalline silicon material has a good response to long-wavelength light (700-1100 nm). The combination of these two materials allows the theoretical photoelectric conversion efficiency of the tandem cell to break through the Shockley-Queisser limit of single-junction cells, reaching over 35%.

[0003] However, the actual efficiency of current tandem solar cells still falls significantly short of theoretical values, with one of the core bottlenecks being energy loss due to spectral mismatch. An ideal tandem structure requires optimal matching between the bandgap of the upper perovskite layer and the bandgap of the lower crystalline silicon layer to achieve graded absorption of photon energy from the standard solar spectrum. However, in practice, the bandgap uniformity of the perovskite film is affected by the fabrication process, easily leading to insufficient absorption in the short-wavelength region or wasted photon energy in the long-wavelength region. Spectral mismatch indirectly leads to a mismatch in carrier generation rates. When the perovskite layer absorbs excessive short-wavelength light, charge accumulation at the interface exacerbates nonradiative recombination, while the saturation of long-wavelength light absorption in the crystalline silicon layer results in current mismatch. These spectral mismatch issues not only restrict the efficiency improvement of tandem solar cells but also place higher demands on material bandgap engineering, interface optical design, and carrier dynamics control.

[0004] In recent years, some studies have focused on the spectral matching problem of tandem solar cells. In the paper J. Phys. Chem. Lett. 2020, 11, 10, 3782–3788, a method for addressing spectral mismatch errors in perovskite solar cells was studied using a commercial AAA-grade solar simulator. The impact of spectral mismatch on the performance of perovskite solar cells was discussed, and corresponding solutions were proposed to improve the accuracy of simulator test results. In practical applications, the paper De Bastiani, M., Mirabelli, AJ, Hou, Y. et al. Efficient bifacialmonolithic perovskite / silicon tandem solar cells via bandgap engineering. NatEnergy 6, 167–175 (2021) investigated the perovskite bandgap required to achieve optimal current matching under different actual illumination and reflectivity conditions. However, in these studies, the same type of perovskite / crystalline silicon tandem solar cell only adapts to one fixed spectrum. In practical applications, under outdoor conditions, when the solar spectrum evolves towards sunrise and sunset with noon as the reference, it exhibits a trend of "sharp reduction in short-wave energy, relative retention of long-wave energy, and decrease in total irradiance" (e.g., Figure 1 As shown in the figure, this dynamic change has a significant impact on the efficiency of photovoltaic devices, and the spectral timeliness needs to be considered according to the actual application scenario.

[0005] This invention provides a perovskite / crystalline silicon tandem solar cell with dynamic spectral response capability. An organic donor-acceptor heterojunction with near-infrared absorption is integrated at the perovskite end. Under real-time spectral changes, it can adaptively adjust the photocurrent of the perovskite sub-cell to match the current of the silicon sub-cell, ensuring the entire tandem solar cell operates at optimal efficiency. This effectively overcomes the dependence of tandem devices on fixed standard spectra, exhibiting superior power generation performance under complex lighting conditions. Furthermore, the low-temperature processing of the organic functional layer is compatible with the perovskite layer's fabrication process, reducing production difficulty and significantly contributing to the practical application of high-efficiency photovoltaic technology. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a perovskite / crystalline silicon tandem solar cell, which achieves adaptive adjustment of short-circuit current under different near-infrared band intensities in the standard spectrum by integrating an organic donor-acceptor heterojunction at the perovskite end, thereby matching the silicon current and maximizing the efficiency and power generation of the tandem solar cell within a certain range.

[0007] This invention provides a perovskite / crystalline silicon tandem solar cell, comprising a silicon bottom cell and a perovskite top cell stacked sequentially from bottom to top. The perovskite top cell includes a hole transport layer, an organic absorber layer, a perovskite absorber layer, a passivation layer, an electron transport layer, a third transparent electrode layer, a second metal electrode layer, and an antireflection layer.

[0008] In this embodiment, the silicon-based solar cell includes a first metal electrode layer, a first transparent electrode layer, a P-type substrate doped layer, a substrate passivation layer, a silicon substrate, a substrate surface passivation layer, an N-type substrate doped layer, and a second transparent electrode layer. The hole transport layer is located on the second transparent electrode layer, and the two are in contact.

[0009] Furthermore, the organic absorber layer comprises at least one organic donor material and at least one organic acceptor material, with their energy levels matched. The highest occupied molecular orbital (HOMO) energy level of the organic donor material is higher than the lowest unoccupied molecular orbital (LUMO) energy level of the organic acceptor material.

[0010] Specifically, the organic donor material comprises at least one of the following materials: poly(3-hexylthiophene) (P3HT), poly(divinylthiophene)-co-benzodithiophene (PDVT-10), poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopentan[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)) (PCPDTBT), poly(thieno[3,4-b]thiophene-co-benzodithiophene) (PTB7), poly(thieno[3,4-b]thiophene-co-thienoylbenzodithiophene), poly(benzodithiophene-co-dithienobenzodithiophene) (PTB7-Th), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2 ​​... (2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (PM6), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (D18), etc.

[0011] Specifically, the organic acceptor material comprises at least one of the following materials: methyl [6,6]-phenyl-C61-butyrate (PCBM), methyl [6,6]-phenyl-C71-butyrate (PC71BM), 3,9-bis(2-methylene-(3-(1,1-dicyanovinyl)-indolone))-5,5,11,11-tetrahexyldithiopheno[2,3-d:2',3'-d']-s-indolo[1,2-b:4,5-b']dithiophene (ITIC), bis(2-((2,6-dicyano-4-(thiophen-2-yl)phenyl)amino)-4,5-difluorothiophen-3-yl)methyl ketone (Y6), etc.

[0012] In the organic absorber layer, organic donor and organic acceptor materials are blended to form an interpenetrating network structure with a thickness ranging from 50 to 500 nm.

[0013] In one embodiment, the first metal electrode layer and the second metal electrode layer are at least one of silver (Ag), gold (Au), copper (Cu), aluminum (Al), and carbon (C);

[0014] In one embodiment, the first transparent electrode layer, the second transparent electrode layer, and the third transparent electrode layer are at least one of indium tin oxide (ITO), indium zinc oxide (IZO), and aluminum zinc oxide (AZO);

[0015] In one embodiment, the hole transport layer is at least one of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly-3-hexylthiophene (P3HT), nickel oxide (NiOx), molybdenum oxide (MoOx), cuprous iodide (CuI), and cuprous thiocyanate (CuSCN);

[0016] In one embodiment, the perovskite absorber layer has an ABX3 structure, where A is an organic cation, including CH3NH3. + (MA + ), NH2CH=NH2 + (FA + CH3CH2NH3 + or Cs + At least one of them;

[0017] B represents metal cations, including Pb. 2+ Sn 2+ At least one of them;

[0018] C represents a halide anion, including F. - Cl - ,Br- I - At least one of them;

[0019] The passivation layer is at least one of the following: propylenediamine iodine (PDADI), propylenediamine bromide (PDADBr), butylamine chloride (BACl), butylamine bromide (BABr), butylamine iodide (BAI), N,N-dimethyl-1,3-propanediamine hydrochloride (DMePDADCl), dodecylamine bromide (DDDADBr), magnesium fluoride, lithium fluoride (LiF), and sodium fluoride (NaF).

[0020] In one embodiment, the electron transport layer is a composite structure formed by stacking at least one or more of the following materials: titanium dioxide (TiO2), tin dioxide (SnO2), zinc oxide (ZnO), C60 (C60), methyl [6,6]-phenyl-C61-butyrate (PCBM), methyl [6,6]-phenyl-C71-butyrate (PC71BM), and indoline fullerene (ICBA).

[0021] In one embodiment, the antireflective layer is at least one of lithium fluoride (LiF), magnesium fluoride (MgF), and polymethyl methacrylate (PMMA);

[0022] Another aspect of the present invention provides a method for fabricating a perovskite-silicon tandem solar cell, the structure of which is as described above, wherein the organic absorber layer includes the following fabrication steps:

[0023] Organic donor and organic acceptor materials are mixed and dissolved in a solvent, ultrasonically dispersed, and then filtered to remove impurities to obtain a donor-acceptor blend solution. The donor-acceptor blend solution is then drop-coated onto a hole transport layer and spin-coated. During the spin-coating process, the solvent evaporates naturally. After spin-coating is completed, the film is annealed to obtain an organic absorber layer.

[0024] Furthermore, the purpose of ultrasonic dispersion in the above steps is to ensure that the donor and acceptor materials are uniformly dissolved and free from agglomeration. The ultrasonic power is 200~400 W, and the ultrasonication is carried out for 10~30 min under a water bath temperature control of 25~40 ℃.

[0025] Furthermore, the spin coating speed is 1000-5000 rpm, and the spin coating time is 20-60 s;

[0026] Furthermore, the annealing temperature range is 80~150 ℃, and the annealing time is 10~30 min.

[0027] Furthermore, in the donor-receptor blend solution, the organic acceptor material accounts for 0.1% to 99.9% of the total mass of the organic acceptor material, and the solution concentration ranges from 10 to 30 mg / mL.

[0028] Preferably, in the acceptor-donor blend solution, the organic acceptor material accounts for 61% of the total mass of the organic acceptor material, and the solution concentration ranges from 11 mg / mL.

[0029] Furthermore, the organic donor material comprises at least one of the following materials: poly(3-hexylthiophene) (P3HT), poly(divinylthiophene)-co-benzodithiophene (PDVT-10), poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopentan[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)) (PCPDTBT), poly(thieno[3,4-b]thiophene-co-benzodithiophene) (PTB7), poly(thieno[3,4-b]thiophene-co-thienoylbenzodithiophene), poly(benzodithiophene-co-dithienobenzodithiophene) (PTB7-Th), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene- 2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (PM6), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (D18), etc.;

[0030] The organic acceptor material comprises at least one of the following materials: methyl [6,6]-phenyl-C61-butyrate (PCBM), methyl [6,6]-phenyl-C71-butyrate (PC71BM), 3,9-bis(2-methylene-(3-(1,1-dicyanovinyl)-indolone))-5,5,11,11-tetrahexyldithiopheno[2,3-d:2',3'-d']-s-indolo[1,2-b:4,5-b']dithiophene (ITIC), bis(2-((2,6-dicyano-4-(thiophen-2-yl)phenyl)amino)-4,5-difluorothiophen-3-yl)methyl ketone (Y6), etc.

[0031] The solvent comprises one or more of the following: chlorobenzene, o-dichlorobenzene, toluene, 1,8-diiodooctane, dimethyl phthalate, 1-chloronaphthalene, etc.

[0032] In this embodiment, the perovskite top cell includes a hole transport layer, an organic absorber layer, a perovskite absorber layer, a passivation layer, an electron transport layer, a third transparent electrode layer, a second metal electrode layer, and an antireflection layer sequentially fabricated on the silicon bottom cell.

[0033] In this embodiment, the silicon-based solar cell includes the following fabrication steps: providing a silicon substrate, depositing a substrate surface passivation layer and a substrate passivation layer on the top and bottom surfaces of the silicon substrate, respectively; subsequently depositing an N-type substrate doped layer and a P-type substrate doped layer on the substrate surface passivation layer and the substrate passivation layer, respectively; then forming a second transparent electrode layer and a first transparent electrode layer on the N-type substrate doped layer and the P-type substrate doped layer, respectively; and finally forming a first metal electrode layer on the first transparent electrode layer.

[0034] In this embodiment, the silicon substrate is an N-type silicon substrate, and both sides are chemically textured in an alkaline solution before preparation to form a pyramid structure with random distribution.

[0035] In this embodiment, the substrate surface passivation layer and the substrate passivation layer are obtained by depositing intrinsic amorphous silicon layers (ia-Si:H) on the top and bottom surfaces of the silicon substrate, respectively, using plasma-enhanced chemical vapor deposition.

[0036] In this embodiment, the N-type substrate doped layer and the P-type substrate doped layer are obtained by plasma-enhanced chemical vapor deposition on the substrate surface passivation layer and the substrate passivation layer, respectively. The P-type substrate doped layer and the N-type silicon substrate form a "pin heterojunction" through the intrinsic layer, thereby constructing a built-in electric field for carrier transport.

[0037] The first transparent electrode layer and the second transparent electrode layer are deposited on the P-type substrate doped layer and the N-type substrate doped layer respectively by magnetron sputtering. Plasma bombardment of the metal oxide target material causes the target material atoms to be deposited on the surface of the target substrate, forming a dense transparent conductive film.

[0038] In this embodiment, the first metal electrode layer is deposited on the first transparent electrode layer by thermal evaporation.

[0039] After the above steps, a silicon-based solar cell is obtained. The silicon-based solar cell is then thermally annealed in an oven and cooled at room temperature. Subsequently, a hole transport layer for the perovskite top solar cell is prepared by magnetron sputtering on the second transparent electrode.

[0040] In a perovskite sub-cell, the perovskite absorber layer absorbs 300-700 nm photons and dissociates into electrons and holes under the influence of a built-in electric field. Electrons generated by the perovskite pass through the electron transport layer to the first metal electrode layer and are collected. Holes generated by the perovskite pass through the donor and hole transport layers in the organic absorber layer to the second transparent electrode layer and recombine with electrons generated in the silicon cell. The organic absorber layer absorbs 700-900 nm photons and dissociates into electrons and holes at the donor-acceptor interface. Electrons generated by the organic absorber layer pass through the perovskite absorber layer and the electron transport layer to the first metal electrode layer and are collected. Holes generated by the organic absorber layer pass through the hole transport layer to the second transparent electrode layer and recombine with electrons generated in the silicon cell.

[0041] The perovskite / crystalline silicon tandem solar cell prepared by the above-described method exhibits a perovskite sub-cell response to short-wavelength light (300-900 nm), while the silicon sub-cell primarily absorbs long-wavelength light (900-1200 nm). The equivalent circuit diagram of the solar cell is shown below. Figure 2 As shown, due to the current limitation in the series circuit, the short-circuit current density of the tandem solar cell is equal to the lower of the silicon sub-cell 300 and the perovskite sub-cell 410. When the short-wavelength energy (300-700 nm) in the solar spectrum decreases sharply and the long-wavelength energy (700-1200 nm) increases, the photogenerated current of the perovskite sub-cell is supplemented by the organic absorption layer from the long-wavelength energy, and the overall current remains unchanged, thus achieving self-adaptation to changes in the solar spectrum.

[0042] Compared with existing technologies, the perovskite / crystalline silicon tandem solar cells prepared by the above method have the following advantages: 1) The band gap of existing perovskite / crystalline silicon tandem solar cells is designed according to the "standard solar spectrum (AM1.5G)," and can only achieve optimal spectral matching under strong midday light. In contrast, the near-infrared absorption of the perovskite sub-cells in the embodiments of this invention is supplemented by the organic absorption layer, and the current is not sensitive to spectral changes. It can match the spectral changes of different scenarios in real time, resulting in significant efficiency advantages; 2) When current mismatch occurs due to spectral mismatch in existing tandem solar cells, excess charge carriers will accumulate at the interface, causing local overheating and intensified charge carrier recombination, ultimately leading to a shortened cell life. The adaptive tandem solar cells in the embodiments of this invention alleviate this problem at its source by dynamically balancing the current. The adaptive adjustment can make the photocurrent of the two layers equal in real time, avoiding sudden local temperature rises and reducing the risk of perovskite layer degradation and crystalline silicon passivation layer failure; 3) Existing tandem solar cells usually require a solar tracker to track light and reduce spectral mismatch, which increases system costs. The adaptive stacked battery in this embodiment of the invention can simplify system design and reduce production costs. Attached Figure Description

[0043] Figure 1This is a schematic diagram of the structure of the perovskite / crystalline silicon tandem solar cell provided by the present invention;

[0044] Figure 2 The equivalent circuit diagram of the tandem solar cell provided by the present invention;

[0045] Figure 3 The solar spectrum at different times of day (morning, noon, and evening) in a certain location during winter in the Northern Hemisphere;

[0046] Figure 4 IV curves of the perovskite / crystalline silicon tandem solar cell in Example 1 of this invention under different solar spectra;

[0047] Figure 5 IV curves of the perovskite / crystalline silicon tandem solar cell in Comparative Example 1 provided by the present invention under different solar spectra.

[0048] 111. Antireflection layer; 112. Second metal electrode layer; 113. Third transparent electrode layer; 114. Electron transport layer; 115. Passivation layer; 116. Perovskite absorber layer; 117. Organic absorber layer; 118. Hole transport layer; 210. Second transparent electrode layer; 211. N-type substrate doped layer; 212. Substrate surface passivation layer; 213. Silicon substrate; 214. Substrate passivation layer; 215. P-type substrate doped layer; 216. First transparent electrode layer; 217. First metal electrode layer.

[0049] 300. Silicon sub-cell portion in the equivalent circuit diagram of a tandem solar cell; 400. Perovskite sub-cell portion in the equivalent circuit diagram of a tandem solar cell. Detailed Implementation

[0050] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0051] In the description of this invention, unless otherwise stated, "a plurality of" 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," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] The present invention provides a method for fabricating a perovskite sub-cell with adaptive spectrum in a perovskite-silicon tandem solar cell, specifically including the following steps:

[0053] (1) A hole transport layer 118 nickel oxide thin film of perovskite top cell was prepared by magnetron sputtering on the prepared silicon bottom cell;

[0054] (2) Organic donor material D18 and organic acceptor material Y6 were dissolved in chloroform solvent at a mass ratio of 1:1.6, with a total solution concentration of 11 mg / ml. The solution was then ultrasonically dispersed for 30 min to 2 h and filtered through a 0.22 μm filter membrane to remove impurities. The organic donor-acceptor solution was drop-coated onto hole transport layer 118 and spin-coated at 1000–5000 rpm for 30–60 s. The solvent evaporated naturally during spin-coating. After spin-coating, the film was annealed at 80 °C for 10 min to optimize the film morphology, resulting in organic absorber layer 117.

[0055] (3) Dissolve CsI:FAI:PbI2:PbBr2 in 1 ml of a DMF:DMSO (4:1 v / v) mixed solvent at a molar ratio of 0.22:0.78:0.775:0.225, where Pb... 2+ Cs was obtained by heating and stirring at 60 °C for 12 h with an ion concentration of 1.5 M and then filtering with a 0.45 μm filter head. 0.22 FA 0.78 Pb(I 0.85 Br 0.15 3. Precursor solution. 120 μL of perovskite precursor solvent was coated on the surface of the organic absorber layer 117 film and spin-coated at 4000 rpm for 30 s. After spin-coating, the film was flash-evaporated under a vacuum of 5 Pa for 60 s, and then annealed at 100 °C for 10 min to obtain the perovskite absorber layer 116.

[0056] (4) To prepare passivation layer 115, 150 μL of PDADI solution with a concentration of 2.5 mg / ml (isopropanol as solvent) was coated on the surface of perovskite absorber layer 116. The solution was spin-coated at 5000 rpm for 30 s, and then annealed at 100°C for 5 min to obtain passivation layer 115.

[0057] (5) Place the obtained film on the mask template and put it into the evaporation chamber of the vapor deposition machine, at a temperature of 1×10⁻⁶. -4 Evaporation was performed under a vacuum of Pa, with an evaporation rate of 0.1–0.15 Å / s to deposit a 20 nm C60 thin film. After complete evaporation and cooling, a 20 nm SnO2 layer was deposited at 100 °C by atomic layer deposition (ALD) to obtain electron transport layer 114.

[0058] (6) Then, a 40 nm transparent indium zinc oxide (IZO) electrode was sputtered using a target material (90% In2O3 + 10% ZnO) with a radio frequency power of 38W to obtain the third transparent electrode layer 113.

[0059] (7) Subsequently, 1 μm of silver was thermally evaporated through a shadow mask to obtain the second metal electrode layer 112.

[0060] (8) Finally, in 1×10 -4 A 100 nm MgF2 antireflective layer, namely antireflective layer 111, was evaporated at a vacuum level of Pa at a rate of 2 Å / s.

[0061] The following will provide specific embodiments and comparative examples to clearly and completely describe the technical solution of the present invention, and to effectively test and compare the devices obtained by the method.

[0062] Example 1:

[0063] This embodiment is a perovskite / crystalline silicon tandem solar cell of the present invention, which is prepared by the above steps (1) to (8).

[0064] Comparative Example 1:

[0065] This comparative example is a perovskite / crystalline silicon tandem solar cell. The organic absorber layer structure described in section 1 was not implemented in this comparative example. The cell was prepared using the following steps:

[0066] (1) A nickel oxide thin film for hole transport layer of perovskite top cell was prepared by magnetron sputtering on the prepared silicon bottom cell;

[0067] (2) Dissolve CsI:FAI:PbI2:PbBr2 in 1 ml of a DMF:DMSO (4:1 v / v) mixed solvent at a molar ratio of 0.22:0.78:0.775:0.225, where Pb... 2+ Cs was obtained by heating and stirring at 60 °C for 12 h with an ion concentration of 1.5 M and then filtering with a 0.45 μm filter head. 0.22 FA 0.78 Pb(I 0.85 Br 0.15 3. Precursor solution. 120 μL of perovskite precursor solvent was coated on the surface of the hole transport layer film and spin-coated at 4000 rpm for 30 s. After spin-coating, the film was flash-evaporated under a vacuum of 5 Pa for 60 s, followed by annealing at 100 °C for 10 min to obtain the perovskite absorber layer.

[0068] (3) To prepare a passivation layer, 150 μL of a 2.5 mg / ml PDADI solution (isopropanol as solvent) was coated onto the surface of the perovskite layer. The solution was spin-coated at 5000 rpm for 30 s, and then annealed at 100°C for 5 min to obtain the passivation layer.

[0069] (4) Place the obtained film on the mask template and put it into the evaporation chamber of the vapor deposition machine. -4 Evaporation was performed under a vacuum of 0.1–0.15 Å / s to deposit a 20 nm C60 thin film. After complete evaporation and cooling, a 20 nm SnO2 layer was deposited at 100 °C using atomic layer deposition (ALD) to obtain the electron transport layer.

[0070] (5) Then, a 40 nm transparent indium zinc oxide (IZO) electrode was sputtered using a target material (90% In2O3 + 10% ZnO) with a radio frequency power of 38W to obtain a third transparent electrode layer.

[0071] (6) Subsequently, 1 μm of silver was thermally evaporated through a shadow mask to obtain the second metal electrode layer.

[0072] (7) Finally, in 1×10 -4 A 100 nm MgF2 antireflective layer, or anti-reflection layer, was evaporated at a rate of 2 Å / s under a vacuum of Pa. The silicon-based solar cell in Example 1 and Comparative Example 1 can employ an HJT structure, consisting of, from bottom to top, a first metal electrode layer 217, a first transparent electrode layer 216, a P-type substrate doped layer 215, a substrate passivation layer 214, a silicon substrate 213, a substrate surface passivation layer 212, an N-type substrate doped layer 211, and a second transparent electrode layer 210. In Example 1 and Comparative Example 1, the silicon substrate 213 is selected from N-type silicon substrates.

[0073] like Figure 1 As shown, solar spectra one to three represent solar spectral irradiance curves measured at different times. IV curves for Example 1 and Comparative Example 1 were measured under the spectra at these times, and the data obtained under the solar spectrum were normalized using the data as the reference unit. Figure 4 As shown, the normalized efficiencies of the solar cell based on the structure described in this invention under three solar spectra are 1, 0.9848, and 1.0086, with a variance of 0.012; while the normalized efficiencies of the solar cell in Comparative Example 1 under the three solar spectra are 1, 0.7742, and 1.0754, with a variance of 0.157. The efficiency variation in Comparative Example 1 mainly stems from current mismatch caused by spectral changes, demonstrating the effectiveness of the tandem solar cell of this invention in adapting to spectral variations.

[0074] Solar cell performance parameters of Example 1

[0075] Normalized current Normalized voltage Normalized fill factor Normalized conversion efficiency Solar Spectrum I 1 1 1 1 Solar Spectrum II 0.9925 1 0.9922 0.9848 Solar Spectrum III 1.0086 1 1 1.0086

[0076] Performance parameters of solar cells in Comparative Example 1

[0077] Normalized current Normalized voltage Normalized fill factor Normalized conversion efficiency Solar Spectrum I 1 1 1 1 Solar Spectrum II 1.0471 0.9969 0.7417 0.7742 Solar Spectrum III 1.0926 1 0.9843 1.0754

[0078] The above embodiments are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle of the present invention. All technical solutions after making equivalent substitutions to the claims of the present invention fall within the protection scope of the present invention, which is defined by the appended claims and their equivalents.

Claims

1. A perovskite / crystalline silicon tandem solar cell, characterized in that, It includes a silicon bottom cell and a perovskite top cell stacked from bottom to top; the perovskite top cell includes a hole transport layer, an organic absorber layer, a perovskite absorber layer, a passivation layer, an electron transport layer, a third transparent electrode layer, a second metal electrode layer, and an antireflection layer.

2. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that, The organic absorber layer comprises at least one organic donor material and at least one organic acceptor material, with their energy levels matched. The highest occupied molecular orbital (HOMO) energy level of the organic donor material is higher than the lowest unoccupied molecular orbital (LUMO) energy level of the organic acceptor material.

3. The perovskite / crystalline silicon tandem solar cell according to claim 2, characterized in that, The organic donor material comprises at least one of the following materials: poly(3-hexylthiophene) (P3HT), poly(divinylthiophene)-co-benzodithiophene (PDVT-10), poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopentan[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)) (PCPDTBT), poly(thieno[3,4-b]thiophene-co-benzodithiophene) (PTB7), poly(thieno[3,4-b]thiophene-co-thienoylbenzodithiophene), poly(benzodithiophene-co-dithienobenzodithiophene) (PTB7-Th), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2- (2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (PM6), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (D18).

4. The perovskite / crystalline silicon tandem solar cell according to claim 2, characterized in that, The organic acceptor material comprises at least one of the following materials: methyl [6,6]-phenyl-C61-butyrate (PCBM), methyl [6,6]-phenyl-C71-butyrate (PC71BM), 3,9-bis(2-methylene-(3-(1,1-dicyanovinyl)-indolone))-5,5,11,11-tetrahexyldithiopheno[2,3-d:2',3'-d']-s-indolo[1,2-b:4,5-b']dithiophene (ITIC), and bis(2-((2,6-dicyano-4-(thiophen-2-yl)phenyl)amino)-4,5-difluorothiophen-3-yl)methyl ketone (Y6).

5. The perovskite / crystalline silicon tandem solar cell according to claim 2, characterized in that, In the organic absorber layer, organic donor and organic acceptor materials are blended to form an interpenetrating network structure with a thickness ranging from 50 to 500 nm.

6. The perovskite / crystalline silicon tandem solar cell according to any one of claims 1 to 5, characterized in that, The silicon-based solar cell includes a first metal electrode layer, a first transparent electrode layer, a P-type substrate doped layer, a substrate passivation layer, a silicon substrate, a substrate surface passivation layer, an N-type substrate doped layer, and a second transparent electrode layer; the hole transport layer is located on the second transparent electrode layer, and the two are in contact.

7. A method for fabricating a perovskite / crystalline silicon tandem solar cell, applied to the perovskite / crystalline silicon tandem solar cell according to any one of claims 1 to 6, characterized in that, The organic absorbent layer includes the following preparation steps: Organic donor and organic acceptor materials are mixed and dissolved in a solvent, ultrasonically dispersed, and then filtered to remove impurities to obtain a donor-acceptor blend solution. The donor-acceptor blend solution is then drop-coated onto a hole transport layer and spin-coated. During the spin-coating process, the solvent evaporates naturally. After spin-coating is completed, the film is annealed to obtain an organic absorber layer.

8. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, In the aforementioned acceptor-donor blend solution, the organic acceptor material accounts for 0.1% to 99.9% of the total mass of the organic acceptor material, and the solution concentration ranges from 10 to 30 mg / mL.

9. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, The purpose of ultrasonic dispersion in the above steps is to ensure that the donor and acceptor materials are uniformly dissolved and free from agglomeration. The ultrasonic power is 200~400 W, and the ultrasonication is carried out for 10~30 min under the temperature control of a water bath at 25~40℃.

10. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, The spin coating speed is 1000-5000 rpm, and the spin coating time is 20-60 s.

11. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, The annealing temperature range is 80~150 ℃, and the annealing time is 10~30 min.

12. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, The organic donor material comprises at least one of the following materials: poly(3-hexylthiophene) (P3HT), poly(divinylthiophene)-co-benzodithiophene (PDVT-10), poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopentan[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)) (PCPDTBT), poly(thieno[3,4-b]thiophene-co-benzodithiophene) (PTB7), poly(thieno[3,4-b]thiophene-co-thienoylbenzodithiophene), poly(benzodithiophene-co-dithienobenzodithiophene) (PTB7-Th), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2- (2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (PM6), poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-methoxythiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-dihexyl-3,4'-dihydro-2'H-spiro[cyclopentane-1,2'-indole]-5',6'-dionitrile))] (D18).

13. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, The organic acceptor material comprises at least one of the following materials: methyl [6,6]-phenyl-C61-butyrate (PCBM), methyl [6,6]-phenyl-C71-butyrate (PC71BM), 3,9-bis(2-methylene-(3-(1,1-dicyanovinyl)-indolone))-5,5,11,11-tetrahexyldithiopheno[2,3-d:2',3'-d']-s-indolo[1,2-b:4,5-b']dithiophene (ITIC), and bis(2-((2,6-dicyano-4-(thiophen-2-yl)phenyl)amino)-4,5-difluorothiophen-3-yl)methyl ketone (Y6).

14. The method for fabricating a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that, The solvent comprises one or more of the following: chlorobenzene, o-dichlorobenzene, toluene, 1,8-diiodooctane, dimethyl phthalate, and 1-chloronaphthalene.

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