A method of adjusting the work function of a tunneling material, a tunneling composite layer, and a stacked battery

Abstract

The application provides a method for adjusting work function of a tunneling material, a tunneling composite layer and a stacked battery, and comprises the following steps: mixing a tunneling material nanocrystal with a solvent to obtain a tunneling material solution; mixing the tunneling material solution with a ligand solution to perform a surface functionalization reaction to adjust the work function of the tunneling material, and obtain a tunneling composite material; the ligand comprises an electron-donating ligand and / or an electron-accepting ligand. The work function of the tunneling material is adjusted by modifying the tunneling material nanocrystal with a ligand, and when the tunneling composite material is used in a stacked battery, the energy level of the tunneling composite layer is efficiently aligned with the energy band of the top and bottom perovskite sub-batteries by flexibly adjusting the work function. This can significantly reduce the carrier transport barrier, and improve the recombination and tunneling efficiency of electrons and holes.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology and relates to a method for adjusting the work function of tunneling materials, a tunneling composite layer, and a stacked cell. Background Technology

[0002] The photoelectric conversion efficiency of single-junction perovskite solar cells is limited by the Shockley-Queisser limit, making further significant improvements difficult. To overcome this limit, tandem solar cells have emerged. Tandem solar cells, by stacking two or more light-absorbing layers with different band gaps, can achieve a wider absorption and utilization of the solar spectrum, thereby effectively improving the cell's photoelectric conversion efficiency. Perovskite tandem cells, especially all-perovskite tandem cells, demonstrate enormous development potential due to the compatibility and tunability of their sub-cell material systems, and are expected to become an important direction for the development of next-generation high-efficiency solar cells.

[0003] In the structural design of tandem solar cells, the tunneling recombination layer is the core functional layer connecting the top and bottom sub-cells, and its performance directly determines the overall photoelectric conversion efficiency of the tandem solar cell. Conventional all-perovskite tandem modules use conductive nanoparticles as the tunneling recombination layer; these nanoparticles can be metal nanoparticles or metal oxide nanoparticles. Using this as the tunneling recombination layer can effectively realize electron-hole recombination, improving the photoelectric conversion efficiency of all-perovskite tandem solar cells and modules.

[0004] The work function of the tunneling material is a key parameter determining the energy level structure of the tunneling composite layer. When the work function of the tunneling material does not match the band structure of the perovskite sub-cell, a high carrier transport barrier will form at the interface between the tunneling composite layer and the sub-cell. This not only hinders the smooth transport of electrons and holes, leading to carrier accumulation at the interface, but also increases the nonradiative recombination loss of carriers, severely reducing the open-circuit voltage, short-circuit current, and fill factor of the tandem cell, ultimately limiting the improvement of the photoelectric conversion efficiency of the tandem cell.

[0005] Currently, there are few tunneling materials available for the fabrication of all-perovskite tandem modules, and these materials generally have a fixed and unique work function that cannot be adjusted or optimized, which greatly limits the efficiency of all-perovskite tandem modules. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for adjusting the work function of tunneling materials, a tunneling composite layer, and a tandem solar cell. This invention achieves adjustment of the work function of the tunneling material nanocrystals through ligand modification. When used in a tandem solar cell, the work function can be flexibly adjusted to achieve efficient alignment between the energy levels of the tunneling composite layer and the energy bands of the top and bottom perovskite sub-cells. This significantly reduces the carrier transport barrier and improves the recombination and tunneling efficiency of electrons and holes.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for adjusting the work function of a tunneling material, the method comprising the following steps:

[0009] The tunneling material nanocrystals are mixed with a solvent to obtain a tunneling material solution;

[0010] By mixing the tunneling material solution with the ligand solution and performing a surface functionalization reaction to adjust the work function of the tunneling material, a tunneling composite material is obtained.

[0011] The ligands in the ligand solution include electron-donating ligands and / or electron-accepting ligands.

[0012] This invention involves improved ligand exchange on nanoparticles. The surface ligands of the nanoparticles are not merely inert protective layers; they fundamentally reconstruct the surface physicochemical environment of the nanocrystals through strong chemical interactions with surface atoms. The ligand molecules themselves possess an inherent dipole moment where the centers of positive and negative charges do not coincide. When they are chemically bonded to the nanocrystal surface through head groups, they form an orderly arranged monopole layer. This dipole layer generates a strong electric field, directly raising or lowering the vacuum energy level at the nanoparticle surface. Since the work function is defined as the energy difference from the Fermi level of a material to the vacuum level, a shift in the vacuum level implies a change in the work function. For example, electron-donating ligands (such as amines) form an outward-facing dipole layer, lowering the vacuum energy level and thus reducing the work function; while electron-accepting ligands (such as carboxylic acids) have the opposite effect, increasing the work function.

[0013] In addition to the direct dipole effect, the ligands described in this invention also influence the electronic structure of nanoparticles by passivating surface states and potentially causing charge transfer. The surface of nanoparticles contains numerous "dangling bonds" formed by interrupted atomic arrangement. These dangling bonds introduce defect levels (surface states) into the band gap, acting like energy traps that can capture charge carriers and pin the Fermi level. When a new ligand effectively saturates these dangling bonds, these surface states can be removed, releasing the pinning of the Fermi level and allowing it to move freely. This not only alters the work function but also makes the band structure "cleaner" and more ideal. Furthermore, significant charge transfer occurs between the ligand and the nanocrystal surface, similar to chemical doping, directly injecting or extracting electrons into the nanoparticles, shifting the Fermi level, and inducing band bending.

[0014] Preferably, the electron-donating ligand comprises oleylamine (OAm).

[0015] Preferably, the electron-accepting ligand comprises mono[2-[(2-methyl-acryloyl)oxy]ethyl succinate (MMES).

[0016] Preferably, the tunneling material nanocrystals include any one or a combination of at least two of the following: indium tin oxide nanocrystals, fluorine-doped tin oxide nanocrystals, aluminum-doped zinc oxide nanocrystals, zinc-doped tin oxide nanocrystals, tungsten-doped indium oxide nanocrystals, zinc-doped indium oxide nanocrystals, indium hydroxide-doped tin oxide nanocrystals, cadmium tin oxide nanocrystals, cerium oxide nanocrystals, indium oxide nanocrystals, tin oxide nanocrystals, or iridium oxide nanocrystals. Typical but non-limiting combinations include combinations of indium tin oxide nanocrystals and fluorine-doped tin oxide nanocrystals, combinations of indium oxide nanocrystals and tin oxide nanocrystals, or combinations of cadmium tin oxide nanocrystals and cerium oxide nanocrystals.

[0017] Preferably, the solvent includes toluene.

[0018] Preferably, the mass concentration of the tunneling material solution is 2% to 5%, for example: 2%, 2.5%, 3%, 4% or 5%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, the solvent of the ligand solution includes any one or a combination of at least two of toluene, chlorobenzene, isopropanol, ethanol, ethyl acetate or methyl propionate.

[0020] Preferably, the mass concentration of the ligand solution is 3% to 7%, for example: 3%, 4%, 5%, 6% or 7%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the method of mixing the tunneling material solution with the ligand solution includes vortex mixing.

[0022] Preferably, the temperature of the surface functionalization reaction is 5℃~100℃, for example: 5℃, 10℃, 20℃, 50℃ or 100℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the surface functionalization reaction time is 0.1h to 6h, for example: 0.1h, 0.5h, 1h, 3h or 6h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] The surface functionalization reaction described in this invention mainly removes excess ligands and byproducts through induced precipitation, and the final nanocrystals are stored in the solution in a uniformly dispersed form.

[0025] Preferably, after the surface functionalization reaction, excess ligands and byproducts are removed by hexane-induced precipitation.

[0026] In a second aspect, the present invention provides a tunneling composite material, wherein the modified tunneling material is prepared by the method described in the first aspect.

[0027] The tunneling composite material of this invention has the characteristic of adjustable work function, which liberates the limitations of material selection and makes more types of nanomaterials with lower cost or better process compatibility potential candidates for tunneling composite layers, no longer limited to a few materials with inherent work functions.

[0028] Thirdly, the present invention provides a tunneling composite layer comprising the tunneling composite material as described in the second aspect.

[0029] The tunneling composite layer made of the tunneling composite material described in this invention can achieve efficient alignment of its energy level with the energy bands of the top and bottom perovskite sub-cells by flexibly adjusting the work function. This significantly reduces the carrier transport barrier and improves the recombination and tunneling efficiency of electrons and holes. Precise band matching and optimized carrier dynamics directly translate into increased device open-circuit voltage and fill factor, representing an effective way to improve the efficiency of current all-perovskite tandem solar cells.

[0030] Fourthly, the present invention provides a stacked battery comprising a tunneling composite layer as described in the third aspect.

[0031] When the tunneling composite material described in this invention is used in tandem solar cells, its work function is adjustable, which allows for the selection of materials that cause less damage to the perovskite layer or are more stable themselves (e.g., avoiding the use of easily migrating gold nanoparticles), thereby simplifying the process and potentially enhancing the long-term operational stability of tandem devices.

[0032] The tandem solar cell of the present invention includes a full perovskite tandem module, comprising two sets of perovskite cells, with the tunneling recombination layer disposed between the two sets of perovskite cells, which can effectively realize electron-hole recombination and improve the photoelectric conversion efficiency of the full perovskite tandem solar cell and module.

[0033] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) This invention modifies the work function of the tunneling material nanocrystals by modifying the ligands. When used in tandem solar cells, the energy levels of the tunneling composite layer are efficiently aligned with the energy bands of the top and bottom perovskite sub-cells by flexibly adjusting the work function. This significantly reduces the carrier transport barrier and improves the recombination and tunneling efficiency of electrons and holes.

[0036] (2) This invention enables the fabrication of perovskite-based tandem solar cells and large-area modules by controllably adjusting the work function of the tunneling material, ultimately achieving a significant improvement in efficiency and stability. Attached Figure Description

[0037] Figure 1 The ultraviolet photoelectron spectra of the tunneling composite materials prepared in Examples 1 and 2 are shown.

[0038] Figure 2 The curves show the performance of the all-perovskite tandem solar cells prepared in Application Example 1 and Comparative Application Example 1.

[0039] Figure 3 The curves are the effect curves of the large-area all-perovskite multilayer module prepared by Example 2. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0041] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0042] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0044] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0045] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0047] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0048] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0049] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0050] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0051] The indium oxide nanocrystals used in the embodiments and comparative examples of this invention were all prepared by the following method:

[0052] Indium(III) acetate (6 mmol), octyl acetate (18 mmol), and oleylamine (50 mmol) were dissolved in a three-necked flask containing 50 mL of octyl ether. The mixture was degassed under vacuum for 90 min to remove residual oxygen and moisture. Under a nitrogen atmosphere, the system temperature was raised to 150 °C and maintained for 1 h to ensure complete reaction of the precursors. The solution was then heated to 280 °C and maintained for 2 h to promote nanocrystal growth. After cooling to room temperature, the crude product was purified by ethanol precipitation to obtain indium oxide nanocrystals.

[0053] Example 1

[0054] This embodiment provides a method for adjusting the work function of tunneling materials, the method comprising the following steps:

[0055] Indium oxide nanocrystals were mixed with toluene to obtain a tunneling material solution with a mass concentration of 2%.

[0056] The tunneling material solution was mixed with a toluene solution with a mass concentration of 5% OAm. After mixing at 25°C, the mixture was stirred for 1 hour to carry out a surface functionalization reaction to adjust the work function of the tunneling material. Excess ligands and byproducts were removed by hexane-induced precipitation to obtain the tunneling composite material (the tunneling composite material is dispersed in the solution and can be directly coated to obtain the tunneling composite layer).

[0057] Example 2

[0058] Indium oxide nanocrystals were mixed with toluene to obtain a tunneling material solution with a mass concentration of 5%.

[0059] The tunneling material solution was mixed with a toluene solution of 7% MMES at 25°C and stirred for 2 hours to carry out a surface functionalization reaction to adjust the work function of the tunneling material. Excess ligands and byproducts were removed by hexane-induced precipitation to obtain the tunneling composite material (the tunneling composite material is dispersed in the solution and can be directly coated to obtain the tunneling composite layer).

[0060] Example 3

[0061] Indium oxide nanocrystals were mixed with toluene to obtain a tunneling material solution with a mass concentration of 3%.

[0062] The tunneling material solution was mixed with a 5% OAm toluene solution, and then heated to 100°C and stirred for 6 hours to carry out a surface functionalization reaction to adjust the work function of the tunneling material. Excess ligands and byproducts were removed by hexane-induced precipitation to obtain the tunneling composite material (the tunneling composite material is dispersed in the solution and can be directly coated to obtain the tunneling composite layer).

[0063] Example 4

[0064] Indium oxide nanocrystals were mixed with toluene to obtain a tunneling material solution with a mass concentration of 1%.

[0065] The tunneling material solution was mixed with a toluene solution with a mass concentration of 2% OAm. After mixing, the mixture was stirred at 20°C for 3 hours to carry out a surface functionalization reaction to adjust the work function of the tunneling material. Excess ligands and byproducts were removed by hexane-induced precipitation to obtain the tunneling composite material (the tunneling composite material is dispersed in the solution and can be directly coated to obtain the tunneling composite layer).

[0066] Example 5

[0067] The only difference between this embodiment and Embodiment 1 is that the mass concentration of the tunneling material solution is 1%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0068] Example 6

[0069] The only difference between this embodiment and Embodiment 1 is that the mass concentration of the tunneling material solution is 6%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0070] Example 7

[0071] The only difference between this embodiment and Example 1 is that the mass concentration of the toluene solution of OAm is 2%, while the other conditions and parameters are exactly the same as in Example 1.

[0072] Example 8

[0073] The only difference between this embodiment and Embodiment 1 is that the mass concentration of the toluene solution of OAm is 8%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0074] Example 9

[0075] The only difference between this embodiment and Example 1 is that the surface functionalization reaction is carried out by mixing and stirring in an oil bath at 150°C for 5 minutes. All other conditions and parameters are exactly the same as in Example 1.

[0076] Example 10

[0077] The only difference between this embodiment and Example 1 is that the surface functionalization reaction was mixed and stirred in an ice bath at 0°C for 6 hours. All other conditions and parameters are exactly the same as in Example 1.

[0078] Comparative Example 1

[0079] This comparative example directly uses indium oxide nanocrystals.

[0080] Application Example 1

[0081] This application example provides an area of ​​0.049 cm². 2 The specific fabrication process of the inverted perovskite-perovskite dual-junction tandem solar cell is as follows:

[0082] (1) The ITO glass substrate was wiped with deionized water, and then ultrasonicated with deionized water, acetone and isopropanol for 30 min each. A nickel oxide hole transport layer with a thickness of 10 nm was deposited on the substrate after ultraviolet ozone treatment.

[0083] (2) Weigh CsI, FAI, PbI2, and PbBr2 in a nitrogen glove box according to the molar ratio. The perovskite composition is Cs 0.35 FA 0.65 PbI 1.8 Br 1.2 The precursor solution was dissolved in a DMF:DMSO = 4:1 solvent, with a concentration of approximately 1 mol / L. A wide-bandgap perovskite film with a thickness of 400 nm was prepared using a blade coating method, followed by thermal evaporation to deposit a 26 nm thick C layer. 60 An electron transport layer of approximately 60 nm SnO2 was deposited using atomic layer deposition.

[0084] (3) The tunneling composite material prepared in Example 1 is coated onto the electron transport layer by a scraping method to form a tunneling composite layer (since the tunneling composite material is dispersed in the solution, it can be directly scraped).

[0085] (4) A 50 nm thick poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) hole transport layer was deposited on the tunneling composite layer. MAI, FAI, PbI2, and SnI2 were weighed in a nitrogen glove box according to the molar ratio. The perovskite composition was FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3 was dissolved in a mixed solvent with a volume ratio of DMF:DMSO = 9:1, and the precursor solution concentration was 2 mol / L. A perovskite thin film with a thickness of 1100 nm was prepared by a blade coating method. A 26 nm thick C layer was then deposited by thermal evaporation. 60A 10 nm layer of SnO2 was deposited using atomic layer deposition, and a 200 nm thick layer of copper was deposited by thermal evaporation to obtain the inverse perovskite-perovskite dual-junction tandem solar cell.

[0086] Application Example 2

[0087] This application example provides an area of ​​65.2 cm². 2 The specific fabrication process of the inverted perovskite-perovskite dual-junction tandem solar cell is as follows:

[0088] (1) P1 was prepared by laser scrubbing on the ITO glass substrate, and then wiped with deionized water. Then, the substrate was ultrasonicated with deionized water, acetone and isopropanol for 30 min each. A nickel oxide hole transport layer with a thickness of 10 nm was deposited on the substrate after ultraviolet ozone treatment.

[0089] (2) Weigh CsI, FAI, PbI2, and PbBr2 in a nitrogen glove box according to the molar ratio. The perovskite composition is Cs 0.35 FA 0.65 PbI 1.8 Br 1.2 The precursor solution was dissolved in a DMF:DMSO = 4:1 solvent, with a concentration of approximately 1 mol / L. A wide-bandgap perovskite film with a thickness of 400 nm was prepared using a blade coating method, followed by thermal evaporation to deposit a 26 nm thick C layer. 60 An electron transport layer of approximately 60 nm SnO2 was deposited using atomic layer deposition.

[0090] (3) The tunneling composite material prepared in Example 2 is coated on the electron transport layer by a scraping method to form a tunneling composite layer (since the tunneling composite material is dispersed in the solution, it can be directly scraped).

[0091] (4) A 50 nm thick poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) hole transport layer was deposited on the tunneling composite layer. MAI, FAI, PbI2, and SnI2 were weighed in a nitrogen glove box according to the molar ratio. The perovskite composition was FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3 was dissolved in a mixed solvent with a volume ratio of DMF:DMSO = 9:1, and the precursor solution concentration was 2 mol / L. A perovskite thin film with a thickness of 1100 nm was prepared by a blade coating method. A 26 nm thick C layer was then deposited by thermal evaporation. 60 A 10 nm SnO2 layer was deposited using atomic layer deposition, and P2 was prepared by laser scribing to expose the ITO bottom electrode, thus obtaining the inverse perovskite-perovskite dual-junction tandem solar cell.

[0092] Application Example 3

[0093] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in example 3, while the other conditions and parameters are exactly the same as in example 1.

[0094] Application Example 4

[0095] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in example 4, while the other conditions and parameters are exactly the same as in example 1.

[0096] Application Example 5

[0097] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in Example 5, while the other conditions and parameters are exactly the same as in Example 1.

[0098] Application Example 6

[0099] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in example 6, while the other conditions and parameters are exactly the same as in example 1.

[0100] Application Example 7

[0101] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in Example 7, while the other conditions and parameters are exactly the same as in Example 1.

[0102] Application Example 8

[0103] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in Example 8, while the other conditions and parameters are exactly the same as in Example 1.

[0104] Application Example 9

[0105] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in Example 9, while the other conditions and parameters are exactly the same as in Example 1.

[0106] Application Example 10

[0107] The only difference between this application example and application example 1 is that the tunneling composite material is prepared using the method of adjusting the work function of the tunneling material described in example 10, while the other conditions and parameters are exactly the same as in example 1.

[0108] Comparative Application Example 1

[0109] The only difference between this comparative application example and application example 1 is that the indium oxide nanocrystals described in comparative example 1 are used as the tunneling layer, while the other conditions and parameters are exactly the same as in example 1.

[0110] Performance testing:

[0111] The current-voltage characteristic curves of the perovskite photovoltaic modules were tested under simulated sunlight, and the test results are shown in Table 1.

[0112] Table 1

[0113]

[0114] As shown in Table 1, based on Application Examples 1-10, the performance of the tandem solar cell fabricated from the surface-ligand-functionalized tunneling material obtained by adjusting the work function of the tunneling material as described in this invention is significantly better than that of the tandem solar cell fabricated from the tunneling material without adjusting the work function, achieving a performance of 0.049 cm⁻¹. 2 The efficiency of the inverse perovskite-perovskite dual-junction tandem solar cell can reach 22.9% or higher, the open-circuit voltage can reach 1.98V or higher, and the current density can reach 15.0mA / cm². 2 With a fill factor of 72.1% or higher, a value of 0.049 cm⁻¹ can be obtained by adjusting the condition parameters in the method. 2 The efficiency of the inverse perovskite-perovskite dual-junction tandem solar cell can reach 24.7% or higher, the open-circuit voltage can reach 2.02V or higher, and the current density can reach 15.3mA / cm². 2 The fill factor can reach 78% or higher, and the large area is 65.2cm². 2 The inverse perovskite-perovskite dual-junction tandem solar cell also achieved excellent results, with an efficiency of up to 21.4%, an open-circuit voltage of up to 28.6V, and a current density of up to 1.05mA / cm². 2 The fill factor can reach 71.3%.

[0115] A comparison of Application Example 1 and Application Examples 5-6 shows that in the method for adjusting the work function of the tunneling material described in this invention, the concentration of the tunneling material solution affects the adjustment effect. Controlling the mass concentration of the tunneling material solution at 2%~5% yields a better effect in adjusting the work function of the tunneling material. If the concentration of the tunneling material solution is too low, it will affect the tunneling recombination effect and the performance parameters. If the concentration of the tunneling material solution is too high, it will affect the non-radiative recombination at the interface and reduce the performance parameters.

[0116] By comparing Application Example 1 and Application Examples 7-8, it can be seen that in the method for adjusting the work function of the tunneling material described in this invention, the concentration of the ligand solution affects the adjustment effect. Controlling the concentration of the ligand solution at 3% to 7% mass fraction results in a better effect on adjusting the work function of the tunneling material. If the concentration of the ligand solution is too low, it cannot play a role in adjusting the work function. If the concentration of the ligand solution is too high, it will hinder the recombination of charge carriers.

[0117] By comparing Application Example 1 and Application Examples 9-10, it can be seen that in the method for adjusting the work function of the tunneling material described in this invention, the temperature of the surface functionalization reaction affects the adjustment effect. Controlling the temperature of the surface functionalization reaction between 5℃ and 100℃ has a better effect on adjusting the work function of the tunneling material. If the temperature of the surface functionalization reaction is too low, the surface ligands cannot be exchanged. If the temperature of the surface functionalization reaction is too high, desorption is easy.

[0118] The ultraviolet photoelectron spectra of the tunneling composite materials prepared in Examples 1 and 2 are as follows: Figure 1 As shown, by Figure 1 It can be seen that the different ligands used in this invention affect both the work function and band structure of indium oxide nanocrystals.

[0119] The effect curve of the tunneling material prepared in Example 2 in a large-area all-perovskite multilayer assembly is shown in the figure below. Figure 3 As shown, by Figure 3 It can be seen that the tunneling composite material obtained by adjusting the work function of the tunneling material as described in this application still achieves significant results when used in large-area all-perovskite stacked components.

[0120] The effect curves of the inverse perovskite-perovskite dual-junction tandem solar cells prepared in Application Example 1 and Comparative Application Example 1 are shown in the figure below. Figure 2 As shown, a comparison between Application Example 1 and Comparative Application Example 1 reveals that indium oxide nanocrystals with ligands exhibit significantly better tunneling recombination performance. This invention, through ligand modification of the tunneling material nanocrystals, achieves adjustment of the work function of the tunneling material. When used in tandem solar cells, the work function can be flexibly adjusted to achieve efficient alignment between the energy levels of the tunneling recombination layer and the energy bands of the top and bottom perovskite sub-cells. This significantly reduces the carrier transport barrier and improves the recombination and tunneling efficiency of electrons and holes.

[0121] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for adjusting the work function of a tunneling material, characterized in that, The method includes the following steps: The tunneling material nanocrystals are mixed with a solvent to obtain a tunneling material solution; By mixing the tunneling material solution with the ligand solution and performing a surface functionalization reaction to adjust the work function of the tunneling material, a tunneling composite material is obtained. The ligands in the ligand solution include electron-donating ligands and / or electron-accepting ligands; The tunneling material nanocrystals include any one or a combination of at least two of the following: indium tin oxide nanocrystals, fluorine-doped tin oxide nanocrystals, aluminum-doped zinc oxide nanocrystals, zinc-doped tin oxide nanocrystals, tungsten-doped indium oxide nanocrystals, zinc-doped indium oxide nanocrystals, indium hydroxide-doped indium hydroxide nanocrystals, cadmium tin oxide nanocrystals, cerium oxide nanocrystals, indium oxide nanocrystals, tin oxide nanocrystals, or iridium oxide nanocrystals. The solvent includes toluene.

2. The method as described in claim 1, characterized in that, The electron-donating ligand includes oleylamine; And / or, the electron-receiving ligand includes mono[2-[(2-methyl-acryloyl)oxy]ethyl] succinate.

3. The method as described in claim 1, characterized in that, The mass concentration of the tunneling material solution is 2% to 5%.

4. The method as described in claim 1, characterized in that, The solvent of the ligand solution includes any one or a combination of at least two of toluene, chlorobenzene, isopropanol, ethanol, ethyl acetate or methyl propionate; And / or, the mass concentration of the ligand solution is 3% to 7%.

5. The method as described in claim 1, characterized in that, The method of mixing the tunneling material solution with the ligand solution includes vortex mixing.

6. The method as described in claim 1, characterized in that, The surface functionalization reaction is carried out at a temperature of 5℃~100℃; And / or, the surface functionalization reaction takes 0.1 h to 6 h.

7. A tunneling composite material, characterized in that, The tunneling composite material is prepared by the method described in any one of claims 1-6.

8. A tunneling composite layer, characterized in that, The tunneling composite layer comprises the tunneling composite material as described in claim 7.

9. A stacked battery, characterized in that, The stacked battery includes the tunneling composite layer as described in claim 8.

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