Tandem solar cell and manufacturing method therefor, photovoltaic module, electric device, and power generation device

Abstract

The present application relates to a tandem solar cell and a manufacturing method therefor, a photovoltaic module, an electric device, and a power generation device. The tandem solar cell comprises a first absorber layer, a recombination layer, and a second absorber layer, wherein the recombination layer is located between the first absorber layer and the second absorber layer. The recombination layer comprises a first interfacial layer and a second interfacial layer opposite to each other, wherein the second interfacial layer is disposed between the first interfacial layer and the second absorber layer. The first interfacial layer comprises an N-type semiconductor, and the second interfacial layer comprises a P-type semiconductor. The N-type semiconductor comprises an N-type perovskite material, and / or the P-type semiconductor comprises a P-type perovskite material.

Description

Tandem solar cells and their fabrication methods, photovoltaic modules, electrical appliances and power generation devices Cross-references

[0001] This application claims priority to Chinese Patent Application No. 202411648341.X, filed on November 18, 2024, entitled “Tannel Solar Cells and Methods for Preparing Themselves, Photovoltaic Modules, Electrical Devices and Power Generation Devices”, which is incorporated herein by reference in its entirety. Technical Field

[0002] This application relates to the field of photovoltaic technology, and in particular to a tandem solar cell and its preparation method, photovoltaic modules, electrical devices, and power generation devices. Background Technology

[0003] A tandem solar cell is an electronic device that directly converts light energy into electrical energy. The main working principle of a tandem solar cell is the photovoltaic effect: when sunlight or other light sources shine on the semiconductor material of the tandem solar cell, the energy of the photons is absorbed by the semiconductor, exciting the generation of electron-hole pairs. Under the influence of an electric field inside the semiconductor, the electrons and holes move in different directions, creating a potential difference across the device. When an external circuit is connected, a current is generated. A tandem solar cell consists of multiple layers of semiconductor materials with different band gaps, forming multiple pn junctions. Its working principle is that materials with different band gaps can absorb different wavelengths of sunlight, thus utilizing sunlight more effectively and achieving more efficient photon capture. The multiple pn junctions work together, increasing the open-circuit voltage and short-circuit current of the cell, thereby improving the conversion efficiency.

[0004] Currently, traditional tandem solar cells typically use tunneling junctions to connect semiconductor materials with different band gaps. However, the structure of traditional tunneling junctions is relatively complex, making the fabrication process complicated and costly. How to simplify the structure of tunneling junctions while maintaining the performance of tandem solar cells is one of the key issues that urgently needs to be addressed. Summary of the Invention

[0005] To achieve the above objectives, this application provides a tandem solar cell and its preparation method, photovoltaic module, power supply device, and power generation device, which simplifies the traditional tunnel junction structure while maintaining good photoelectric conversion performance.

[0006] The first aspect of this application provides a tandem solar cell, comprising:

[0007] A first light-absorbing layer, a composite layer, and a second light-absorbing layer, wherein the composite layer is located between the first light-absorbing layer and the second light-absorbing layer;

[0008] The composite layer includes a first interface layer and a second interface layer opposite to each other, wherein the second interface layer is disposed between the first interface layer and the second light-absorbing layer;

[0009] The first interface layer comprises an N-type semiconductor, the second interface layer comprises a P-type semiconductor, the N-type semiconductor comprises an N-type perovskite material, and / or the P-type semiconductor comprises a P-type perovskite material.

[0010] The composite layer in the tandem solar cell provided in this application can replace the traditional tunnel junction. Compared with the traditional tunnel junction structure composed of a wide bandgap carrier transport layer, a charge recombination layer, and a narrow bandgap carrier transport layer, it can eliminate the intermediate charge recombination layer, which simplifies the structure of the tunnel junction, reduces the fabrication process, and lowers the fabrication cost. Moreover, since the composite layer of this application can still carry out normal carrier transport and recombination after eliminating the intermediate layer, the tandem solar cell can still maintain good photoelectric conversion performance.

[0011] In some embodiments, the N-type semiconductor comprises an N-type perovskite material, and the P-type semiconductor comprises a P-type perovskite material.

[0012] In some embodiments, the first interface layer is in direct contact with the second interface layer.

[0013] In some embodiments, the N-type perovskite material comprises materials satisfying the chemical formula AlPbI. 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2 One or more of the compounds;

[0014] Among them, A1 and A2 each independently include Cs + FA + MA + and Rb + One or more of them, X1 includes Ag + Cu + Na + Li + K + 、Rb + Cs + Ni 2+ Cu 2+ Zn 2+ Co 2+ Bi 3+ Ga 3+ In 3+ Sb 3+ Al3+ 、Tl 3+ and Co 3+ One or more of the following, 0≤a1≤3, 0.001≤b1≤0.01, 0≤a2≤3.

[0015] In some embodiments, the N-type perovskite material comprises materials satisfying the chemical formula AlPbI. 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2 One or more of the compounds;

[0016] Among them, A1 and A2 each independently include Cs + and FA + One or two of them, X1 includes Ag + , 0≤a1≤3, 0.001≤b1≤0.01, 0≤a2≤3.

[0017] In some embodiments, the p-type perovskite material comprises materials satisfying the chemical formula A3SnI3 or A4Sn. 1-b2 X2 b2 One or more of the compounds containing I3;

[0018] Among them, A3 and A4 each independently include Cs + FA + MA + and Rb + One or more of them, X2 includes Sb 3+ Bi 3+ Ag + Cu + Na + Li + K + 、Rb + Cs + Ni 2+ Cu 2+ Zn 2+ Co 2+ Ga 3+ In 3+ Al 3+ 、Tl 3+ and Co 3+ One or two of them, 0.001≤b2≤0.01.

[0019] In some embodiments, the p-type perovskite material comprises materials satisfying the chemical formula A3SnI3 or A4Sn. 1-b2 X2 b2One or more of the compounds containing I3;

[0020] Among them, A3 and A4 each independently include Cs + and FA + One or two of them, X2 includes Sb 3+ , 0.001≤b2≤0.01.

[0021] In some implementations, one or more of the following conditions are met:

[0022] (1) In the first interface layer, the electron concentration is 10. 20 pcs / cm 3 ~10 21 pcs / cm 3 The hole concentration is 10 14 pcs / cm 3 ~10 15 pcs / cm 3 ;

[0023] (2) In the second interface layer, the hole concentration is 10. 18 pcs / cm 3 ~10 19 pcs / cm 3 The electron concentration is 10 15 pcs / cm 3 ~10 16 pcs / cm 3 .

[0024] In some implementations, one or more of the following conditions are met:

[0025] (1) In the first interface layer, the band gap of the N-type semiconductor is 1.6eV to 2.5eV;

[0026] (2) In the second interface layer, the band gap of the P-type semiconductor is 1.35eV to 1.45eV.

[0027] In some embodiments, the thickness of the first interface layer and the second interface layer are each independently 15 nm to 50 nm.

[0028] In some embodiments, the defect state density at the interface adjacent to the first interface layer and the second interface layer is 10. 10 cm -3 ·eV -1 ~10 11 cm -3 ·eV -1 .

[0029] In some embodiments, the HOMO energy level of the first interface layer is less than the HOMO energy level of the first light-absorbing layer, the LUMO energy level of the second interface layer is greater than the LUMO energy level of the second light-absorbing layer, and the HOMO energy level of the first interface layer is less than the HOMO energy level of the second interface layer.

[0030] In some implementations, one or more of the following conditions are met:

[0031] (1) The HOMO energy level of the first interface layer is -4.0 eV to -4.5 eV;

[0032] (2) The HOMO energy level of the second interface layer is -3.0 eV to -3.55 eV;

[0033] (3) The LUMO energy level of the second interface layer is -4.5eV to -5.0eV.

[0034] In some implementations, one or more of the following conditions are met:

[0035] (1) The HOMO energy level of the first light-absorbing layer is -3.8 eV to -4.0 eV;

[0036] (2) The LUMO energy level of the second light-absorbing layer is -5.0eV to -5.4eV.

[0037] In some embodiments, the first light-absorbing layer comprises a wide bandgap perovskite material, and the second light-absorbing layer comprises a narrow bandgap perovskite material.

[0038] In some embodiments, the wide-bandgap perovskite material satisfies the chemical formula: Y1PbI 3-d1 Br d1 Y1 includes Cs + FA + MA + and Rb + One or more of them, 0.6≤d1<1.8.

[0039] In some embodiments, the wide-bandgap perovskite material includes FA. 0.8 Cs 0.2 Pb(I 0.62 Br 0.38 3. FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 3. FA 0.15 Cs 0.85 Pb(I 0.73 Br 0.27 3. Cs 0.12 MA0.05 FA 0.83 Pb(I 0.6 Br 0.4 )3 and FA 0.2 Cs 0.8 Pb(I 0.67 Br 0.33 One or more of 3.

[0040] In some embodiments, the narrow bandgap perovskite material satisfies the chemical formula: Y₂Pb 1-d2 Sn d2 I3, Y2 including Cs + FA + MA + and Rb + One or more of them, 0.2≤d2≤0.7.

[0041] In some embodiments, the narrow bandgap perovskite material includes MA 0.3 FA 0.7 Pb 0.5 Sn 0.5 I3, MAPb 0.85 Sn 0.15 I3, FAPb 0.5 Sn 0.5 I3 and FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 One or more of I3.

[0042] In some implementations, one or more of the following conditions are met:

[0043] (1) The band gap of the wide bandgap perovskite material is 1.6 eV to 2.0 eV;

[0044] (2) The band gap of the narrow band gap perovskite material is 1.2eV to 1.4eV.

[0045] In some embodiments, the stacked solar cell further includes:

[0046] First electrode and second electrode;

[0047] The first light-absorbing layer is disposed between the first electrode and the first interface layer, and the second light-absorbing layer is disposed between the second interface layer and the second electrode.

[0048] In some embodiments, one of the first electrode and the second electrode is a transparent electrode.

[0049] In some embodiments, the stacked solar cell further includes:

[0050] First charge transport layer and second charge transport layer;

[0051] The first charge transport layer is disposed between the first electrode and the first light-absorbing layer, and the second charge transport layer is disposed between the second light-absorbing layer and the second electrode.

[0052] In some embodiments, one of the first charge transport layer and the second charge transport layer is an electron transport layer and the other is a hole transport layer.

[0053] In some embodiments, the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer.

[0054] A second aspect of this application also provides a method for preparing a tandem solar cell, comprising:

[0055] A first light-absorbing layer, a composite layer, and a second light-absorbing layer are formed, with the composite layer located between the first light-absorbing layer and the second light-absorbing layer, to prepare the stacked solar cell;

[0056] The composite layer includes a first interface layer and a second interface layer, which are disposed between the first interface layer and the second light-absorbing layer.

[0057] The first interface layer comprises an N-type semiconductor, the second interface layer comprises a P-type semiconductor, the N-type semiconductor comprises an N-type perovskite material, and / or the P-type semiconductor comprises a P-type perovskite material.

[0058] A third aspect of this application provides a photovoltaic module, including the tandem solar cell described in the first aspect of this application or the tandem solar cell prepared by the method described in the second aspect of this application.

[0059] A fourth aspect of this application provides an electrical device comprising one or more of the tandem solar cells described in the first aspect of this application, tandem solar cells prepared by the method described in the second aspect of this application, and photovoltaic modules described in the third aspect of this application.

[0060] The fifth aspect of this application provides a power generation device, including one or more of the tandem solar cells described in the first aspect of this application, the photovoltaic module described in the second aspect of this application, and the photovoltaic module described in the third aspect of this application.

[0061] The photovoltaic modules, electrical appliances, and power generation devices of this application include the tandem solar cells provided in this application, and therefore have at least the same advantages as the tandem solar cells.

[0062] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort. In the drawings:

[0064] Figure 1 is a schematic diagram of a stacked solar cell according to an embodiment of this application.

[0065] Figure 2 is a schematic diagram of a stacked solar cell according to an embodiment of this application.

[0066] Figure 3 is a schematic diagram of an electrical device according to an embodiment of this application.

[0067] Reference numerals: 10 First light-absorbing layer; 20 Composite layer; 30 Second light-absorbing layer; 40 First electrode; 50 Second electrode; 60 First charge transport layer; 70 Second charge transport layer; 210 First interface layer; 220 Second interface layer. Detailed Implementation

[0068] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0069] The "range" disclosed in this application 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 a particular range. Ranges defined in this way can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be combined arbitrarily, 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 a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. 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 application, unless otherwise stated, the numerical range "ab" 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 "0-5" have been listed in this document; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, stating that a parameter is an integer ≥2 is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, stating that a parameter is an integer selected from "2-10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0070] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0071] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0072] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0073] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably 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, if the method may also include step (c), it means 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.

[0074] In this application, unless otherwise stated, A (e.g., B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0075] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0076] In tandem solar cells, the tunneling junction is a key component affecting cell performance. It allows photogenerated carriers (electrons and holes) to be efficiently transported between sub-cells made of different materials, thus connecting the sub-cells in series and making the total voltage the sum of the sub-cell voltages, thereby improving the overall output performance of the cell. Currently, in traditional tandem solar cells, the tunneling junction typically consists of a wide-bandgap carrier transport layer, a charge recombination layer, and a narrow-bandgap carrier transport layer. This type of tunneling junction has many layers and a complex structure, requiring a large amount of material during fabrication and involving multiple deposition processes, resulting in high manufacturing costs.

[0077] To address the aforementioned technical problems, this application proposes a tandem solar cell that uses a composite layer comprising N-type perovskite material and / or P-type perovskite material instead of a traditional tunnel junction to connect semiconductor materials with different band gaps. This simplifies the tunnel junction structure while maintaining good photoelectric conversion performance. The tandem solar cell will be described in detail below.

[0078] In a first aspect, this application provides a tandem solar cell, as shown in the example of FIG1, which includes a first light-absorbing layer 10, a composite layer 20 and a second light-absorbing layer 30, wherein the composite layer 20 is located between the first light-absorbing layer 10 and the second light-absorbing layer 30.

[0079] The composite layer 20 includes a first interface layer 210 and a second interface layer 220 opposite to each other, with the second interface layer 220 disposed between the first interface layer 210 and the second light-absorbing layer 30.

[0080] The first interface layer 210 includes an N-type semiconductor, and the second interface layer 220 includes a P-type semiconductor. The N-type semiconductor includes an N-type perovskite material, and / or the P-type semiconductor includes a P-type perovskite material.

[0081] The tandem solar cell provided in this application uses a composite layer instead of a traditional tunnel junction. In this composite layer, the first interface layer contains N-type perovskite material, and / or the second interface layer contains P-type perovskite material. Since N-type perovskite material can not only transport electrons and P-type perovskite material can not only transport holes, but these two perovskite materials can also facilitate the recombination of electrons and holes. Therefore, this composite layer can act as a carrier transport and recombination layer. Compared with the traditional tunnel junction structure of wide-bandgap carrier transport layer-charge recombination layer-narrow-bandgap carrier transport layer, the composite layer of this application can eliminate the intermediate charge recombination layer, thus simplifying the structure of the tunnel junction, reducing fabrication steps, and lowering fabrication costs. Moreover, since the composite layer of this application can still carry out normal carrier transport and recombination after eliminating the intermediate layer, the tandem solar cell can still maintain good photoelectric conversion performance.

[0082] It is understood that in the tandem solar cell of this application, the first light-absorbing layer, the composite layer and the second light-absorbing layer can be stacked; in the composite layer, the first interface layer and the second interface layer can also be stacked.

[0083] It is understood that the N-type semiconductor and P-type semiconductor described in this application have meanings known in the art. The N-type perovskite material refers to a material that inherently contains perovskite components, and in which the electron concentration is greater than the hole concentration; the P-type perovskite material refers to a material that inherently contains perovskite components, and in which the electron concentration is less than the hole concentration.

[0084] It can be understood that the perovskite composition mentioned above refers to compounds that can satisfy the chemical formula A'B'X'3 or A'2C'D'X'6. In this formula, A' ion is a monovalent cation, B' ion is a divalent cation, C' ion is a monovalent cation, D' ion is a trivalent cation, and X' ion is a monovalent anion. A' ion includes organic cations, Li... + Na + K + 、Rb + and Cs +One or more of the following; the organic cation includes at least one selected from methylamino, ethylamino, propylamino, butylamino, pentamino, hexamino, formamidinyl, and imidazolyl; the B' ion includes Pb 2+ Sn 2+ Be 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Zn 2+ 、Ge 2+ Fe 2+ Co 2+ Cu 2+ and Ni 2+ One or more of the following; C' ions include Cs + Ag + K + and Ru + One or more of the following; D' ions include Bi 3+ Ni 3+ Fe 3+ and Cu 3+ One or more of the following; X' ions include F - Cl - ,Br - I - CN - SCN - OCN - One or more of them.

[0085] As an example, in a tandem solar cell, the method for obtaining N-type and P-type semiconductors is as follows: Starting from the side surface of the first light-absorbing layer away from the second light-absorbing layer, take a sample of a certain thickness (e.g., 2 / 3 thickness) along the direction away from the second light-absorbing layer to the top layer of the cell as a sample of the first interface layer; starting from the side surface of the second light-absorbing layer away from the first light-absorbing layer, take a sample of a certain thickness (e.g., 1 / 3 thickness) along the direction away from the first light-absorbing layer to the bottom layer of the cell as a sample of the second interface layer for subsequent testing.

[0086] As an example, inductively coupled plasma mass spectrometry (ICP-MS) can be used to test the samples of the first and second interface layers to determine the elemental distribution and proportion, thus obtaining the sample composition. Similarly, the relative concentrations of holes and electrons in the sample can be measured using dark-state capacitance-voltage (CV) curves to determine whether the first interface layer contains N-type perovskite material and the second interface layer contains P-type perovskite material. An exemplary dark-state capacitance-voltage (CV) curve testing method is as follows: Sample powder is deposited onto a transparent electrode. Using a three-electrode system, the working electrode is the electrode prepared from the sample, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a Pt electrode. The CV curve measured using an electrochemical workstation within the -2V to 2V open voltage range is then subjected to Mott-Schottky analysis to calculate the relative concentrations of holes and electrons in the material.

[0087] In some embodiments, the N-type semiconductor comprises N-type perovskite material, and the P-type semiconductor comprises P-type perovskite material. Thus, both the first and second interface layers can not only transport charge carriers but also facilitate electron-hole recombination. That is, the first and second interface layers can simultaneously serve as carrier transport and recombination layers, thereby simplifying the structure of traditional tunnel junctions while maintaining good photoelectric conversion performance.

[0088] In some embodiments, the N-type semiconductor comprises an N-type perovskite material, the P-type semiconductor comprises a P-type perovskite material, and the first interface layer is in direct contact with the second interface layer.

[0089] When the first interface layer and the second interface layer are in direct contact, and the first interface layer and the second interface layer respectively contain N-type perovskite material and P-type perovskite material, the contact between the perovskite materials will form a continuous band bend, which is beneficial to the transport and recombination of charge carriers, thereby improving the photoelectric conversion performance of the tandem solar cell.

[0090] In some embodiments, the first light-absorbing layer is in direct contact with the first interface layer, the first interface layer is in direct contact with the second interface layer, and the second interface layer is in direct contact with the second light-absorbing layer. Thus, these four interconnected stacked layers can simultaneously serve as carrier transport layers without the need for additional transport layers; simultaneously, the first and second interface layers can also serve as carrier recombination layers, eliminating the need for the charge recombination layer found in traditional tunnel junctions.

[0091] In some embodiments, the N-type perovskite material comprises materials satisfying the chemical formula AlPbI. 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2One or more of the compounds; wherein A1 and A2 each independently include Cs + FA + (Ethylammonium ion, C2H5NH3) + MA + (Ammonium carbamate ion, CH3NH4) + ) and Rb + One or more of them, X1 includes Ag + Cu + Na + Li + K + 、Rb + Cs + Ni 2+ Cu 2+ Zn 2+ Co 2+ Bi 3+ Ga 3+ In 3+ Sb 3+ Al 3+ 、Tl 3+ and Co 3+ One or more of the following, 0≤a1≤3, 0.001≤b1≤0.01, 0≤a2≤3; optionally, 1.8≤a1≤3, 1.8≤a2≤3.

[0092] The compound satisfies the chemical formula AlPbI 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2 In this way, the composition of the compound is essentially controlled, making the perovskite material N-type. This allows the first interface layer containing the compound to function as a transport and recombination layer for charge carriers.

[0093] In some embodiments, the N-type perovskite material comprises materials satisfying the chemical formula AlPbI. 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2 One or more of the compounds; wherein A1 and A2 each independently include Cs + and FA + One or two of them, X1 includes Ag + 0≤a1≤3, 0.001≤b1≤0.01, 0≤a2≤3. Thus, the first interface layer provides better transport and recombination of charge carriers, enabling the tandem solar cell to have better photoelectric conversion performance.

[0094] In some embodiments, the N-type perovskite material includes CsPbBr3, CsPbI2Br, and Cs 0.2 FA 0.8 PbBr3, FAPbI 2.55 Br 0.45 FA 0.8 Cs 0.2 PbI2Br, CsPbI3 and CsPb 0.998 Ag 0.002 One or more of Br3. Optionally, N-type perovskite materials include CsPbBr3, CsPbI2Br, and Cs 0.2 FA 0.8 PbBr3, FA 0.8 Cs 0.2 PbI2Br and CsPb 0.098 Ag 0.002 One or more of Br3. When N-type perovskite materials include these compounds, the transport and recombination of charge carriers are better, enabling tandem solar cells to have better photoelectric conversion performance.

[0095] In some embodiments, the p-type perovskite material comprises materials satisfying the chemical formula A3SnI3 or A4Sn. 1-b2 X2 b2 One or more of the compounds of I3; wherein A3 and A4 each independently include Cs + FA + MA + and Rb + One or more of them, X2 includes Sb 3+ Bi 3+ Ag + Cu + Na + Li + K + 、Rb + Cs + Ni 2+ Cu 2+ Zn 2+ Co 2+ Ga 3+ In 3+ Al 3+ 、Tl 3+ and Co 3+ One or two of them, 0.001≤b2≤0.01.

[0096] The compound satisfies the chemical formula A3SnI3 or A4Sn 1-b2 X2 b2At I3, the composition of the compound is essentially controlled, making the perovskite material p-type. This allows the second interface layer containing the compound to function as a transport and recombination layer for charge carriers.

[0097] In some embodiments, the p-type perovskite material comprises materials satisfying the chemical formula A3SnI3 or A4Sn. 1-b2 X2 b2 One or more of the compounds of I3; wherein A3 and A4 each independently include Cs + and FA + One or two of them, X2 includes Sb 3+ 0.001≤b2≤0.01. Thus, the second interface layer has a better effect on the transport and recombination of charge carriers, enabling the tandem solar cell to have better photoelectric conversion performance.

[0098] In some embodiments, the p-type perovskite material includes FASnI3, CsSnI3, and FA. 0.5 MA 0.5 I3, FA 0.8 Cs 0.2 SnI3 and FASn 0.992 Sb 0.008 One or more of I3 compounds. When p-type perovskite materials include these compounds, the transport and recombination effects of charge carriers are better, enabling tandem solar cells to have better photoelectric conversion performance.

[0099] In some embodiments, the electron concentration in the first interface layer is 10. 20 pcs / cm 3 ~10 21 pcs / cm 3 The hole concentration is 10 14 pcs / cm 3 ~10 15 pcs / cm 3 In this way, the first interface layer can have a better electron transport effect.

[0100] In some embodiments, the hole concentration in the second interface layer is 10. 18 pcs / cm 3 ~10 19 pcs / cm 3 The electron concentration is 10 15 pcs / cm 3 ~10 16 pcs / cm 3 In this way, the second interface layer can have a better hole transmission effect.

[0101] As an example, the concentrations of holes and electrons in the first and second interface layers can be tested using the following method: Using the samples of the first and second interface layers obtained above as test samples, the concentrations of electrons and holes in the first and second interface layers can be measured by analyzing the capacitance-voltage (CV) curves of the test samples in the dark state. The method for measuring the capacitance-voltage (CV) curves in the dark state is described above and will not be repeated here.

[0102] In some embodiments, the band gap of the N-type semiconductor in the first interface layer is 1.6 eV to 2.5 eV. For example, the band gap of the N-type semiconductor can be 1.6 eV, 1.7 eV, 1.8 eV, 1.9 eV, 2.0 eV, 2.1 eV, 2.2 eV, 2.3 eV, 2.4 eV, 2.5 eV, or any range of these values. This allows the energy band of the N-type semiconductor to be positioned appropriately, enabling it to satisfy carrier transport and recombination.

[0103] In some embodiments, the band gap of the P-type semiconductor in the second interface layer is 1.35 eV to 1.45 eV. For example, the band gap of the P-type semiconductor can be 1.35 eV, 1.37 eV, 1.4 eV, 1.43 eV, 1.45 eV, or within any range of these values. This allows the energy band of the P-type semiconductor to be positioned appropriately to accommodate carrier transport and recombination.

[0104] The band gaps of N-type and P-type semiconductors are well-known in the art and can be measured using methods known in the art. As an example, samples of the first and second interface layers obtained above can be used as test samples, and measured by ultraviolet-visible absorption spectroscopy. For instance, if the sample is directly subjected to ultraviolet-visible absorption spectroscopy and the measured absorption cutoff edge is a nm, then the band gap = 1240 / a (eV).

[0105] In some embodiments, the thicknesses of the first interface layer and the second interface layer are each independently between 15 nm and 50 nm. For example, the thicknesses of the first interface layer and the second interface layer can each be independently 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or within any range of these values. This allows for more efficient transport and recombination of electrons and holes, and provides a higher current density, thereby enabling the tandem solar cell to possess excellent photoelectric conversion performance.

[0106] In some embodiments, the defect state density at the interface adjacent to the first interface layer and the second interface layer is 10. 10 cm-3 ·eV -1 ~10 11 cm -3 ·eV -1 Within this range, the defect state density can minimize its impact on carrier mobility and carrier lifetime in the composite layer, thus enabling the tandem solar cell to maintain good photoelectric conversion performance.

[0107] In this application, the defect state density at the interface adjacent to the first interface layer and the second interface layer refers to the density of electronic states generated due to the presence of defects at the interface adjacent to the first interface layer and the second interface layer. As an example, this defect state density can be tested using the space charge-confined current (SCLC) method for tandem solar cells. An exemplary test method for the space charge-confined current (SCLC) method is as follows:

[0108] A sandwich structure is formed by stacking the first and second interface layers with electrodes. In this sandwich structure, the stacked structure of the first and second interface layers is in the middle, and electrodes (such as FTO / stacked structure / metal) are on both sides, thus constructing a device. The current-voltage (JV) characteristics of the device are then measured under dark conditions to determine the current behavior in the absence of photogenerated carriers, obtaining the SCLC curve. At high voltages, when the number of injected carriers is sufficient to form a space charge region in the stacked structure, the relationship between current density (J) and electric field (E) follows the Mott-Gurney law: J = ε × ε0 × μ × (V² / L), where ε is the dielectric constant of the stacked structure, ε0 is the vacuum dielectric constant, μ is the carrier mobility, V is the voltage, and L is the sample thickness. The defect state density can be calculated from the slope of the SCLC curve. In the SCLC region, the current density is proportional to the square of the electric field, while the slope is related to the defect state density. By linearly fitting the SCLC region of the SCLC curve, the slope of the straight line can be obtained, and the defect state density can be calculated.

[0109] In some embodiments, the HOMO energy level of the first interface layer is less than the HOMO energy level of the first light-absorbing layer, the LUMO energy level of the second interface layer is greater than the LUMO energy level of the second light-absorbing layer, and the HOMO energy level of the first interface layer is less than the HOMO energy level of the second interface layer. This facilitates the transport and recombination of charge carriers in the composite layer.

[0110] In this application, the HOMO (Highest Occupied Molecular Orbital) level refers to the highest occupied molecular orbital energy level; the LUMO (Lowest Unoccupied Molecular Orbital) level refers to the lowest unoccupied molecular orbital energy level.

[0111] As an example, HOMO levels can be measured using ultraviolet photoelectron spectroscopy (UPS). For instance, samples from the first and second interface layers obtained earlier can be used as test samples. These samples are placed in the sample chamber of the UPS instrument (high vacuum environment). By exciting the valence band electrons on the sample surface with ultraviolet light, the valence band position (VB / HOMO), work function (Ф), and ionization potential (IE) information can be obtained. In UPS testing, the He I line (energy hν = 21.22 eV) is typically used as the excitation source. The HOMO level can be determined by measuring the maximum valence band value of the sample. For the sample under test, the VBM or HOMO level can be determined by linear extrapolation from the steep rise of the valence band starting edge in the UPS spectrum and taking its intersection with the background noise baseline. LUMO levels can be measured using low-energy reflected photoelectron spectroscopy (LEIPS). For instance, samples from the first and second interface layers obtained earlier can be used as test samples, and LEIPS testing can be performed on the samples. LEIPS uses low-energy electrons (less than 5 eV) as the incident source, which couple to the unoccupied states (conduction band) on the sample surface. By detecting the emitted photons, it obtains information about the sample's conduction band (CB / LUMO) and electron affinity (EA). LEIPS measurements provide information about the sample's conduction band position, thereby determining the LUMO energy level. The testing methods for the HOMO and LUMO energy levels of the first absorbing layer are similar to those for the second interface layer.

[0112] In some embodiments, the HOMO energy level of the first interface layer is -4.0 eV to -4.5 eV. For example, the HOMO energy level of the first interface layer can be -4.0 eV, -4.1 eV, -4.2 eV, -4.3 eV, -4.5 eV, -4.5 eV, or within any of the above values.

[0113] In some embodiments, the HOMO energy level of the second interface layer is -3.0 eV to -3.55 eV. For example, the HOMO energy level of the second interface layer can be -3.0 eV, -3.1 eV, -3.2 eV, -3.3 eV, -3.5 eV, -3.5 eV, -3.55 eV, or within any of the above values.

[0114] In some embodiments, the LUMO energy level of the second interface layer is -4.5 eV to -5.0 eV. For example, the LUMO energy level of the second interface layer can be -4.5 eV, -4.6 eV, -4.7 eV, -4.8 eV, -4.9 eV, -5.0 eV, or within any range of the above values.

[0115] In some embodiments, the HOMO energy level of the first light-absorbing layer is -3.8 eV to -4.0 eV. For example, the HOMO energy level of the first light-absorbing layer can be -3.8 eV, -3.9 eV, -4.0 eV, or within any range of the above values.

[0116] In some embodiments, the LUMO energy level of the second light-absorbing layer is -5.0 eV to -5.4 eV. For example, the LUMO energy level of the second light-absorbing layer can be -5.0 eV, -5.1 eV, -5.2 eV, -5.3 eV, -5.4 eV, or within any of the above values.

[0117] In some embodiments, the tandem solar cell of this application is a tandem perovskite cell.

[0118] In some embodiments, the first light-absorbing layer comprises a wide-bandgap perovskite material, and the second light-absorbing layer comprises a narrow-bandgap perovskite material.

[0119] It is understood that the terms "wide" and "narrow" in the wide-bandgap perovskite materials and narrow-bandgap perovskite materials described in this application are relative, i.e., the bandgap of the wide-bandgap perovskite material is greater than that of the narrow-bandgap perovskite material.

[0120] It is understandable that the "wide bandgap" and "narrow bandgap" in the aforementioned perovskite light-absorbing layer are relative; that is, the bandgap of the first light-absorbing layer is larger than that of the second light-absorbing layer. Thus, when sunlight enters from the wide bandgap perovskite light-absorbing layer, shorter wavelengths are first absorbed and utilized by the wide bandgap perovskite light-absorbing layer, while longer wavelengths can penetrate and be absorbed and utilized by the narrower bandgap perovskite light-absorbing layer, maximizing the conversion of light energy into electrical energy.

[0121] When the first light-absorbing layer includes a wide-bandgap perovskite material and the second light-absorbing layer includes a narrow-bandgap perovskite material, since the first interface layer and / or the second interface layer also contain perovskite material, the first interface layer and / or the second interface layer can be better compatible with the adjacent first light-absorbing layer and / or the second light-absorbing layer. This can reduce defects and charge accumulation problems at the interface between the first light-absorbing layer and the first interface layer, and / or at the interface between the second light-absorbing layer and the second interface layer, thereby reducing the adverse effects on carrier transport and improving the photoelectric conversion performance of the battery.

[0122] In some embodiments, the wide-bandgap perovskite material satisfies the chemical formula: Y1PbI 3-d1 Br d1 Y1 includes Cs + FA + MA + and Rb + One or more of the following, 0.6≤d1<1.8. When wide-bandgap perovskite materials satisfy this chemical formula, tandem solar cells can have better photoelectric conversion performance.

[0123] In some embodiments, the wide-bandgap perovskite material includes FA. 0.8 Cs 0.2 Pb(I 0.62 Br 0.38 3. FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 3. FA 0.15 Cs 0.85 Pb(I 0.73 Br 0.27 3. Cs 0.12 MA 0.05 FA 0.83 Pb(I 0.6 Br 0.4 )3 and FA 0.2 Cs 0.8 Pb(I 0.67 Br 0.33 One or more of 3.

[0124] In some embodiments, the narrow bandgap perovskite material satisfies the chemical formula: Y₂Pb 1-d2 Sn d2 I3, Y2 including Cs + FA + MA + and Rb + One or more of the following, 0.2≤d2≤0.7. When narrow-bandgap perovskite materials satisfy this chemical formula, tandem solar cells can have better photoelectric conversion performance.

[0125] In some embodiments, the narrow bandgap perovskite material includes MA 0.3 FA 0.7 Pb 0.5 Sn 0.5 I3, MAPb 0.85 Sn 0.15 I3, FAPb 0.5 Sn 0.5 I3 and FA 0.7 MA 0.3 Pb0.5 Sn 0.5 One or more of I3.

[0126] In some embodiments, the band gap of the wide bandgap perovskite material is 1.6 eV to 2.0 eV. For example, the band gap of the wide bandgap perovskite material can be 1.6 eV, 1.7 eV, 1.8 eV, 1.9 eV, 2.0 eV, or within any range of the above values.

[0127] In some embodiments, the band gap of the narrow band gap perovskite material is 1.2 eV to 1.4 eV. For example, the band gap of the narrow band gap perovskite material can be 1.2 eV, 1.3 eV, 14 eV, or within any range of the above values.

[0128] The band gaps of wide-bandgap perovskite materials and narrow-bandgap perovskite materials fall within the aforementioned ranges, which allows for better synergy between the two, thus enabling excellent absorption and utilization of solar energy and improving photoelectric conversion efficiency.

[0129] In this application, the band gap testing methods for wide-bandgap perovskite materials and narrow-bandgap perovskite materials are similar to those for N-type perovskite materials or P-type perovskite materials, as described above, and will not be repeated here.

[0130] In some embodiments, as shown in the example of Figure 1, the tandem solar cell further includes:

[0131] First electrode 40 and second electrode 50;

[0132] The first light-absorbing layer 10 is disposed between the first electrode 40 and the first interface layer 210, and the second light-absorbing layer 5 is disposed between the second interface layer 220 and the second electrode 50.

[0133] In some embodiments, one of the "first electrode" and the "second electrode" is a transparent electrode for light incident. One of the first electrode and the second electrode is used to collect electron carriers transported via the electron transport layer, and the other is used to collect hole carriers transported via the hole transport layer.

[0134] In some embodiments, the first electrode is a transparent electrode.

[0135] In some embodiments, the first electrode comprises a transparent conductive oxide.

[0136] In some embodiments, the second electrode comprises a conductive material, which may further be an organic conductive material, an inorganic conductive material, or a combination thereof. Inorganic conductive materials include one or more of transparent conductive metal oxides, metals and their alloys, carbon derivatives, etc. Organic conductive materials include electropolymers, and conductive polymers include one or more of poly(3,4-ethylenedioxythiophene) (PEDOT), polythiophene, polyacetylene, etc.

[0137] In some embodiments, the transparent conductive oxide includes one or more of FTO (fluorine-doped tin oxide), ITO (tin-doped indium oxide), lanthanide-doped indium oxide, AZO (aluminum-doped zinc oxide), antimony-doped tin oxide, BZO (boron-doped zinc oxide), aluminum-doped zinc oxide (AZO), IZO (indium zinc oxide), gallium zinc oxide (GZO), and IWO (tungsten-doped indium oxide).

[0138] In some embodiments, the metallic material includes one or more of gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), chromium (Cr), bismuth (Bi), platinum (Pt), magnesium (Mg), molybdenum (Mo), tungsten (W), and their alloys.

[0139] In some embodiments, the carbon derivative includes at least one of graphite, graphene, and carbon nanotubes.

[0140] In some embodiments, as shown in the example of FIG2, the tandem solar cell further includes:

[0141] First charge transport layer 60 and second charge transport layer 70;

[0142] The first charge transport layer 60 is disposed between the first electrode 40 and the first light-absorbing layer 10, and the second charge transport layer 70 is disposed between the second light-absorbing layer 30 and the second electrode 50.

[0143] In some embodiments, one of the first charge transport layer and the second charge transport layer is an electron transport layer, and the other is a hole transport layer. The electron transport layer can extract and transport electron carriers and block the passage of free holes. The hole transport layer can extract and transport hole carriers and block the passage of free electrons.

[0144] In some embodiments, the first charge transport layer is a hole transport layer and the second charge transport layer is an electron transport layer.

[0145] In some embodiments, the electron transport layer may include, but is not limited to, one or more of the following materials and their derivatives: imide compounds, quinone compounds, fullerenes and their derivatives, methoxytriphenylamine-fluoroformamidinium (OMeTPA-FA), calcium titanate (CaTiO3), lithium fluoride (LiF), calcium fluoride (CaF2), poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), poly3-hexylthiophene (P3HT), triphenylamine with a triphenylene core (H101), 3,4-ethylenedioxythiophene-methoxytriphenylamine (EDOT-OMeTPA), N-(4-aniline)carbazole-spiro Bifluorene (CzPAF-SBF), polythiophene, first metal oxide, silicon oxide (SiO2), strontium titanate (SrTiO3), cuprous thiocyanate (CuSCN), etc.; wherein, the metal element in the first metal oxide may include one or more of magnesium (Mg), nickel (Ni), cadmium (Cd), zinc (Zn), indium (In), lead (Pb), molybdenum (Mo), tungsten (W), antimony (Sb), bismuth (Bi), copper (Cu), mercury (Hg), titanium (Ti), silver (Ag), manganese (Mn), iron (Fe), vanadium (V), tin (Sn), zirconium (Zr), strontium (Sr), gallium (Ga), and chromium (Cr).

[0146] In some embodiments, the hole transport layer may include, but is not limited to, one or more of the following materials and their derivatives: 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), polytriarylamine (PTAA), nickel oxide (NiO). x Materials such as poly(3,4-ethylenedioxythiophene), polystyrene sulfonate (PEDOT:PSS), and WO3 can transport holes and block electrons.

[0147] In some embodiments, the tandem solar cell further includes a substrate layer disposed on the side of the first electrode layer that is relatively far from the first light-absorbing layer, or the substrate layer disposed on the side of the second electrode layer that is relatively far from the second light-absorbing layer.

[0148] In some embodiments, the substrate layer may be, but is not limited to, a glass substrate or a flexible substrate. The flexible substrate may include one or more materials selected from polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, etc.

[0149] It is understood that the structure of the tandem solar cell involved in this application is not limited to the structural layers listed above. Other functional layers, such as buffer layers, can also be introduced as needed. In some embodiments, the tandem solar cell can be provided with a buffer layer of appropriate energy level, which can play one or more of the following roles: reducing energy level barrier, promoting energy level matching, improving carrier extraction efficiency, passivating interface defect states, protecting the light absorption layer, inhibiting the oxidative decomposition of the cell by water molecules and oxygen, improving photoelectric conversion efficiency, and improving the stability of perovskite cells. Depending on the location of the buffer layer, the type of buffer layer can include four types: a buffer layer between the hole transport layer and the anode, a buffer layer between the electron transport layer and the cathode, a buffer layer between the hole transport layer and the light absorption layer, and a buffer layer between the electron transport layer and the light absorption layer.

[0150] Secondly, this application also provides a method for preparing a tandem solar cell, which can be used to prepare the tandem solar cell of the first aspect of this application, and may include the following steps:

[0151] A first light-absorbing layer, a composite layer, and a second light-absorbing layer are formed, with the composite layer located between the first light-absorbing layer and the second light-absorbing layer, to prepare the stacked solar cell;

[0152] The composite layer includes a first interface layer and a second interface layer, which are disposed between the first interface layer and the second light-absorbing layer.

[0153] The first interface layer comprises an N-type semiconductor, the second interface layer comprises a P-type semiconductor, the N-type semiconductor comprises an N-type perovskite material, and / or the P-type semiconductor comprises a P-type perovskite material.

[0154] The tandem solar cell fabricated by the method provided in this application uses a composite layer instead of a traditional tunnel junction. In this composite layer, the first interface layer contains N-type perovskite material, and / or the second interface layer contains P-type perovskite material. Since N-type perovskite material can not only transport electrons and P-type perovskite material can not only transport holes, but these two perovskite materials can also facilitate the recombination of electrons and holes. Therefore, this composite layer can act as a carrier transport and recombination layer to facilitate carrier transport and recombination. Compared with the traditional tunnel junction structure of wide-bandgap carrier transport layer-charge recombination layer-narrow-bandgap carrier transport layer, the composite layer of this application can eliminate the intermediate charge recombination layer, thus simplifying the structure of the tunnel junction, reducing fabrication steps, and lowering fabrication costs. Moreover, since the composite layer of this application can still facilitate normal carrier transport and recombination after eliminating the intermediate layer, the tandem solar cell can still maintain good photoelectric conversion performance.

[0155] In some embodiments, the method for preparing the composite layer may include the following steps:

[0156] Step S10: Based on the composition of N-type semiconductors and P-type semiconductors, select the precursor material corresponding to the N-type semiconductor and the precursor material corresponding to the P-type semiconductor, respectively, and denot them as N-type precursor material and P-type precursor material.

[0157] Step S11: The N-type precursor material is deposited on one side of the first light-absorbing layer by surface co-evaporation, and the first interface layer is prepared after the first annealing treatment.

[0158] Step S12: The P-type precursor material is deposited on one side of the first interface layer using the surface co-evaporation method, and the second interface layer is prepared after a second annealing treatment.

[0159] In steps S10 to S12 above, the first interface layer and the second interface layer are prepared by surface co-evaporation, which can make the element distribution in the first interface layer and the second interface layer more uniform and facilitate the transport of charge carriers in the composite layer.

[0160] In some embodiments, the N-type semiconductor includes an N-type perovskite material, and the N-type perovskite material comprises materials satisfying the chemical formula AlPbI. 3-a1 Br a1 When the compound is used, the N-type precursor material includes AlZ1 and PbZ2, Z1 and Z2 each independently include at least one of Br and I, and at least one of Z1 and Z2 includes Br.

[0161] Based on the chemical formula AlPbI 3-a1 Br a1 Based on the stoichiometric ratio, AlZ1 and PbZ2 were selected as N-type precursor materials; and by controlling the molar ratio of AlZ1 and PbZ2, AlPbI2 could be prepared. 3-a1 Br a1 The perovskite material can be made to be N-type.

[0162] In some embodiments, the N-type semiconductor includes an N-type perovskite material, and the N-type perovskite material comprises materials satisfying the chemical formula A₂Pb. 1-b1 X1 b1 I 3-a2 Br a2 When the compound is used, the N-type precursor material includes A2Z3, PbZ4 and X1Z5, wherein Z3, Z4 and Z5 each independently include at least one of Br and I, and at least one of Z3, Z4 and Z5 includes Br.

[0163] In some embodiments, the molar amount of X1Z5 is 0.1% to 1% of the molar amount of Pb, that is, the molar amount of X1Z5 is 0.001 mol / mol (Pb) to 0.01 mol / mol (Pb).

[0164] Based on the chemical formula A2Pb 1-b1 X1 b1 I 3-a2 Br a2 By determining the stoichiometric ratio, A2Z3, PbZ4, and X1Z5 were selected as N-type precursor materials; and by controlling the molar ratio of the three, the desired N-type precursor material, A2Pb, could be obtained. 1-b1 X1 b1 I 3-a2 Br a2 The perovskite material can be made to be N-type.

[0165] In some embodiments, the P-type semiconductor includes a P-type perovskite material, and when the P-type perovskite material includes a compound satisfying the chemical formula A3SnI3, the P-type precursor material includes A3I and SnI2.

[0166] Based on the stoichiometric ratio of the chemical formula A3SnI3, A3I and SnI2 are selected as P-type precursor materials; and by controlling the molar ratio of A3I and SnI2, perovskite materials that meet the chemical formula A3SnI3 can be prepared, and the perovskite material can be made to be more N-type.

[0167] In some embodiments, the P-type semiconductor includes a P-type perovskite material, and the P-type perovskite material comprises materials satisfying the chemical formula A4Sn. 1-b2 X2 b2 When I3 is a compound, the p-type precursor materials include A4I, SnI2 and X2I, wherein the molar amount of X2I is 0.1% to 1% of the molar amount of Sn, that is, the molar amount of X2I is 0.001 mol / mol (Sn) to 0.01 mol / mol (Sn).

[0168] Based on the chemical formula A4Sn 1-b2 X2 b2 To determine the stoichiometric ratio of I3, A4I, SnI2, and X2I were selected as p-type precursor materials; and by controlling the molar ratio of the three, the desired p-type precursor material (A4SnI2) could be obtained. 1-b2 X2 b2 I3 perovskite material, and can make the perovskite material more P-type.

[0169] In some embodiments, the method for preparing the first light-absorbing layer may include the following steps:

[0170] Step S20: Based on the chemical formula Y1PbI that the wide-bandgap perovskite material satisfies... 3-d1Br d1 Select a wide-bandgap precursor material that corresponds to it, the wide-bandgap precursor material includes Y1R1 and PbR1'2, the molar ratio of Y1R1 and PbR1'2 is consistent with the stoichiometry of the chemical formula, wherein R1 and R1' each independently include at least one of I and Br.

[0171] Step S21: Using a solution spin coating method, the wide-bandgap precursor material is prepared into a precursor solution, which is then spin-coated onto the substrate layer. After vacuum flash evaporation and a third annealing treatment, the first light-absorbing layer is prepared.

[0172] In some embodiments, the method for preparing the second light-absorbing layer may include the following steps:

[0173] Step S30: Based on the chemical formula Y2Pb satisfied by the narrow bandgap perovskite material 1-d2 Sn d2 I3, select the corresponding narrow bandgap precursor material, which includes Y2I, PbI2 and SnI2, wherein the molar ratio of Y2I, PbI2 and SnI2 is consistent with the stoichiometry of the chemical formula;

[0174] Step S31: The narrow bandgap precursor material is deposited on one side of the second interface layer by surface co-evaporation, and the second light-absorbing layer is prepared after the fourth annealing treatment.

[0175] In steps S30 to S31, the second light-absorbing layer is prepared by surface co-evaporation, which can reduce the damage to the second interface layer caused by the solution spin coating method, improve the quality of the second interface layer, and thereby improve the photoelectric performance of the tandem solar cell.

[0176] Thirdly, this application also provides a photovoltaic module, including a tandem solar cell of the first aspect of this application or a tandem solar cell prepared by the method of the second aspect of this application.

[0177] In some embodiments, the photovoltaic module may include only the tandem solar cell of the first aspect of this application, or may combine the tandem solar cell with other solar cells. For example, the tandem solar cell may be combined with a silicon solar cell.

[0178] Fourthly, this application also provides an electrical device, including one or more of the following: a tandem solar cell according to the first aspect of this application, a tandem solar cell prepared by the method of the second aspect of this application, and a photovoltaic module according to the third aspect of this application.

[0179] In some embodiments, the electrical device may include mobile devices, such as mobile phones, laptops, electric vehicles, electric trains, ships and satellites, power generation systems, etc., but is not limited thereto. Figure 3 is an example of an electrical device. This electrical device is a car, and may further be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. As another example, the electrical device may be a wearable device, such as a watch.

[0180] Fifthly, this application also provides a power generation device, including one or more of the tandem solar cell of the first aspect of this application, the tandem solar cell prepared by the method of the second aspect of this application, and the photovoltaic module of the third aspect of this application.

[0181] In some embodiments, the type of power generation device may include, but is not limited to, integrated power generation. The location of the power generation device may include, but is not limited to, the roof or back panel of a vehicle.

[0182] Example

[0183] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0184] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0185] Example 1

[0186] (1) Take 20 pieces of FTO conductive glass with a specification of 2.0×2.0cm, remove 0.35cm of FTO from each end by laser etching to expose the glass substrate; use cleaning solution, deionized water and ethanol to ultrasonically clean the etched FTO conductive glass several times in sequence; then blow the solvent dry under nitrogen gun and put it into the ultraviolet ozone generator for further cleaning.

[0187] (2) On an FTO substrate treated with ultraviolet ozone, 0.5 mg / mL of MeO-2PACz ([2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid) (ethanol as solvent) was spin-coated at a rate of 2000 rpm / s in a glove box for 30 s. The substrate was then annealed on a hot plate at 100 ℃ for 10 min to prepare a hole transport layer with a thickness of 15 nm.

[0188] (3) Weigh out 17.02 mg CsBr, 31.18 mg CsI, 39.99 mg FABr, 82.55 mg FAI, 139.46 mg PbBr2, and 285.83 mg PbI2 in sequence, add 1 mL of solvent (a mixture of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) at a ratio of 4:1 by volume), stir to dissolve for 2 h, and then filter through a 0.22 μm organic filter to obtain the perovskite precursor solution. Spin-coat the perovskite precursor solution onto the obtained hole transport layer at 5000 rpm / s for 25 s, then place it in a vacuum flash evaporator for 30 s, and finally anneal it on a 100℃ hot plate for 15 min to prepare the wide-bandgap perovskite material FA. 0.8 Cs 0.2 Pb(I 0.62 Br 0.38 The first light-absorbing layer of 3 has a thickness of 380 nm; wide-bandgap perovskite material FA 0.8 Cs 0.2 Pb(I 0.62 Br 0.38 The band gap of )3 is 1.8 eV, and the HOMO level is -3.9 eV.

[0189] (4) CsBr and PbBr2 are deposited on the first light-absorbing layer by surface co-evaporation to form an N-type perovskite material CsPbBr3; wherein, the initial evaporation rate of CsBr is The rate is constant; the initial evaporation rate of PbBr2 is... The deposition rate was constant; the total thickness of the vapor deposition was 15 nm; the layer was transferred to a hot stage and annealed at 120 °C for 15 min to prepare the first interface layer.

[0190] (5) FAI and SnI2 are deposited on the first interface layer by surface co-evaporation to form a P-type perovskite material FASnI3; wherein the initial evaporation rate of FAI is: The rate is constant; the initial evaporation rate of SnI2 is The deposition rate was kept constant; the total thickness of the vapor deposition was 15 nm; the vapor was transferred to a hot stage and annealed at 100 °C for 10 min to prepare the second interface layer.

[0191] (6) PbI2, SnI2, and FAI are deposited on the second interface layer by surface co-evaporation to form a narrow bandgap perovskite material FAPb. 0.5 Sn 0.5 I3; where the initial evaporation rate of FAI The rate is constant; the initial evaporation rates of SnI2 and PbI2 are... The deposition rate was constant; the total evaporation thickness was 1 μm; the material was transferred to a hot stage and annealed at 100 °C for 10 min to prepare the second light-absorbing layer; narrow bandgap perovskite material FAPb 0.5 Sn 0.5 The band gap of I3 is 1.2 eV, and the LUMO level is -5.1 eV.

[0192] (7) Electron transport layer, buffer layer and electrode C60 / BCP / Cu were deposited by vapor deposition. The thicknesses of the electron transport layer, buffer layer and electrode were 25nm, 8nm and 90nm, respectively, to prepare a tandem perovskite solar cell.

[0193] Example 2

[0194] Similar to the preparation process in Example 1, the main difference is that in step (4), AgBr is doped into PbBr2, and the molar amount of AgBr is 0.2% of the molar amount of PbBr2, so that the N-type perovskite material is CsPb. 0.998 Ag 0.002 Br3.

[0195] Example 3

[0196] Similar to the preparation process in Example 1, the main difference is that in step (5), SbI3 is doped into SnI2, and the molar amount of SbI3 is 0.8% of the molar amount of SnI2, so that the p-type perovskite material is FASn. 0.992 Sb 0.008 I3.

[0197] Example 4

[0198] Similar to the preparation process in Example 1, the main difference is that in step (4), FAI, PbI2, and PbBr2 are deposited on the first light-absorbing layer by surface co-evaporation, and the evaporation rates of FAI, PbI2, and PbBr2 are respectively... The composition of N-type perovskite materials is adjusted to FAPbI 2.55 Br 0.45 This results in a band gap of 1.60 eV for N-type perovskite materials.

[0199] Example 5

[0200] Similar to the preparation process in Example 1, the main difference is that in step (4), CsBr, PbI2, and FABr are deposited on the first light-absorbing layer by surface co-evaporation, and the evaporation rates of CsBr, PbI2, and FABr are respectively... The composition of N-type perovskite materials is controlled to be FA. 0.8 Cs 0.2 PbI2Br makes the band gap of N-type perovskite material 2.5eV.

[0201] Example 6

[0202] Similar to the preparation process in Example 1, the main difference is that in step (5), CsI, SnI2, and FAI are deposited on the second interface layer by surface co-evaporation, and the evaporation rates of CsI, SnI2, and FAI are respectively... The composition of P-type perovskite materials is controlled by FA. 0.8 Cs 0.2 SnI3 makes the band gap of the P-type perovskite material 1.45eV.

[0203] Example 7

[0204] Similar to the preparation process in Example 1, the main difference is that in step (4), PbBr2 is replaced with an equimolar amount of PbI2, so that the composition of the N-type perovskite material is CsPbI3.

[0205] Example 8

[0206] Similar to the preparation process in Example 1, the main difference is that in step (5), FAI and SnI2 are replaced with equimolar amounts of FABr and SnBr2, so that the composition of the P-type perovskite material is FASnBr3.

[0207] Comparative Example 1

[0208] Similar to the preparation process in Example 1, the main difference is that steps (4) and (5) are omitted, and the first and second interface layers are replaced by a traditional tunneling junction structure (wide bandgap carrier transport layer-charge recombination layer-narrow bandgap carrier transport layer). The specific preparation process is as follows:

[0209] On the first light-absorbing layer, 25 nm C60 was vacuum-deposited as an electron transport layer; on the electron transport layer, 30 nm SnOx was atomically deposited as a solvent barrier layer; on this basis, 5 nm Au was deposited as a charge recombination layer; then, 1 mg / mL MeO-2PACz IPA solution was spin-coated at a rate of 3000 rpm / s for 30 s to obtain a 10 nm film; then, the second light-absorbing layer and subsequent film were prepared according to steps (5) to (7) of Example 1.

[0210] Comparative Example 2

[0211] Similar to the preparation process in Example 1, the main difference is that steps (4) and (5) are swapped, that is, the positions of the first interface layer and the second interface layer are swapped. A second interface layer containing P-type perovskite material is prepared on the first light-absorbing layer (wide bandgap), and a first interface layer containing N-type perovskite material is prepared on the second interface layer.

[0212] The parameters and performance test results of the above embodiments and comparative examples are shown in Tables 1 to 3 below. Among them, "defect state density" refers to the defect state density of the interface between the first interface layer and the second interface layer.

[0213] Table 1

[0214] Table 2

[0215] Test methods

[0216] (1) Photoelectric conversion efficiency

[0217] Under normal temperature and pressure, and under standard simulated sunlight (AM 1.5G, 100 mW / cm²), the battery performance was tested, and the IV curve (volt-ampere characteristic curve) was obtained. Based on the IV curve and the data fed back by the testing equipment (four-channel digital source meter, Keithley 2440), the short-circuit current density Jsc (mA / cm²), open-circuit voltage Voc (volts), maximum light output current Jmpp (mA), and maximum light output voltage Vmpp (V) can be obtained.

[0218] The fill factor FF of the battery can be calculated using the formula FF = Jsc × Voc / (Jmpp × Vmpp), in percentage (%). The photoelectric conversion efficiency PCE of the battery can be calculated using the formula PCE = Jsc × Voc × FF / Pw, in percentage (%); Pw represents the input power, in milliwatts (mW).

[0219] "Normal temperature and pressure" refers to normal pressure: the pressure is one atmosphere at a temperature of 25℃; normal temperature refers to 20℃ to 30℃, and further, it can be 25℃.

[0220] Table 3

[0221] Comparing Examples 1-8 with Comparative Example 1, it can be seen that, compared with the traditional tunnel junction structure, the composite layer of this application not only simplifies the structure of the tunnel junction and reduces the fabrication process, but also allows the battery to maintain good photoelectric conversion efficiency, and can even improve the photoelectric conversion efficiency. Comparing Examples 1-8 with Comparative Example 2, it can be seen that when the composite layer contains a first interface layer with an N-type semiconductor and a second interface layer with a P-type semiconductor, and these are matched with the types of the first and second light-absorbing layers, respectively, a high photoelectric conversion efficiency can be achieved.

[0222] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0223] The embodiments described above merely illustrate various implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A tandem solar cell, comprising: A first light-absorbing layer, a composite layer, and a second light-absorbing layer, wherein the composite layer is located between the first light-absorbing layer and the second light-absorbing layer; The composite layer includes a first interface layer and a second interface layer opposite to each other, wherein the second interface layer is disposed between the first interface layer and the second light-absorbing layer; The first interface layer comprises an N-type semiconductor, the second interface layer comprises a P-type semiconductor, the N-type semiconductor comprises an N-type perovskite material, and / or the P-type semiconductor comprises a P-type perovskite material.

2. The laminated solar cell of claim 1, wherein, The N-type semiconductor includes N-type perovskite material, and the P-type semiconductor includes P-type perovskite material.

3. The tandem solar cell according to claim 1 or 2, wherein The first interface layer is in direct contact with the second interface layer.

4. The tandem solar cell according to any one of claims 1 to 3, wherein The N-type perovskite material includes one or more of a compound that satisfies the chemical formula A1PbI 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2 ​ Among them, A1 and A2 each independently include Cs + FA + MA + and Rb + One or more of them, X1 includes Ag + Cu + Na + Li + K + 、Rb + Cs + Ni 2+ Cu 2+ Zn 2+ Co 2+ Bi 3+ Ga 3+ In 3+ Sb 3+ Al 3+ 、Tl 3+ and Co 3+ One or more of the following, 0≤a1≤3, 0.001≤b1≤0.01, 0≤a2≤3.

5. The tandem solar cell according to any one of claims 1 to 4, wherein The N-type perovskite material includes one or more of a compound that satisfies the chemical formula A1PbI 3-a1 Br a1 or A2Pb 1-b1 X1 b1 I 3-a2 Br a2 ​ wherein A1and A2each independently comprise Cs + and FA + one or both of which, X1comprises Ag + 0≤a1≤3, 0.001≤b1≤0.01, 0≤a2≤3.

6. The tandem solar cell according to any one of claims 1 to 5, wherein The P-type perovskite material includes one or more of compounds that satisfy the chemical formula A3SnI3 or A4Sn 1-b2 X2 b2 I3 Among them, A3 and A4 each independently include Cs + FA + MA + and Rb + One or more of them, X2 includes Sb 3+ Bi 3+ Ag + Cu + Na + Li + K + 、Rb + Cs + Ni 2+ Cu 2+ Zn 2+ Co 2+ Ga 3+ In 3+ Al 3+ 、Tl 3+ and Co 3+ One or two of them, 0.001≤b2≤0.

01.

7. The tandem solar cell according to any one of claims 1 to 6, wherein The P-type perovskite material includes one or more of a compound that satisfies the chemical formula A3SnI3 or A4SnI3 1-b2 X2 b2 I3 wherein A3and A4each independently comprise Cs + and FA + one or both of A2and A3comprise Sb 3+ 0.001 < b2 < 0.

01.

8. The tandem solar cell according to any one of claims 1 to 7, wherein One or more of the following conditions must be met: (1) In the first interface layer, the electron concentration is 10. 20 pcs / cm 3 ~10 21 pcs / cm 3 The hole concentration is 10 14 pcs / cm 3 ~10 15 pcs / cm 3 ; (2) In the second interface layer, the concentration of holes is 10 18 cm 3 -1 19 , and the concentration of electrons is 10 3 cm 15 -1 3 -10 16 cm 3 -1 .

9. The tandem solar cell according to any one of claims 1 to 8, wherein One or more of the following conditions must be met: (1) In the first interface layer, the band gap of the N-type semiconductor is 1.6eV to 2.5eV; (2) In the second interface layer, the band gap of the P-type semiconductor is 1.35eV to 1.45eV.

10. The tandem solar cell according to any one of claims 1 to 9, wherein The thickness of the first interface layer and the second interface layer are each independently 15nm to 50nm.

11. The tandem solar cell according to any one of claims 1 to 10, wherein The interface between the first interface layer and the second interface layer has a defect state density of 10 10 cm -3 · eV -1 ~ 10 11 cm -3 · eV -1 .

12. The tandem solar cell according to any one of claims 1 to 11, wherein The HOMO energy level of the first interface layer is less than the HOMO energy level of the first light-absorbing layer, the LUMO energy level of the second interface layer is greater than the LUMO energy level of the second light-absorbing layer, and the HOMO energy level of the first interface layer is less than the HOMO energy level of the second interface layer.

13. The laminated solar cell of claim 12, wherein, One or more of the following conditions must be met: (1) The HOMO energy level of the first interface layer is -4.0 eV to -4.5 eV; (2) The HOMO energy level of the second interface layer is -3.0 eV to -3.55 eV; (3) The LUMO energy level of the second interface layer is -4.5eV to -5.0eV.

14. The tandem solar cell according to claim 12 or 13, wherein, One or more of the following conditions must be met: (1) The HOMO energy level of the first light-absorbing layer is -3.8 eV to -4.0 eV; (2) The LUMO energy level of the second light-absorbing layer is -5.0eV to -5.4eV.

15. The tandem solar cell according to any one of claims 1 to 14, wherein The first light-absorbing layer comprises a wide-bandgap perovskite material, and the second light-absorbing layer comprises a narrow-bandgap perovskite material.

16. The laminated solar cell of claim 15, wherein, The wide bandgap perovskite material satisfies the chemical formula: Y1PbI 3-d1 Br d1 , Y1 includes one or more of Cs + , FA + , MA + , and Rb + , 0.6≤d1<1.

8.

17. The laminated solar cell of claim 16, wherein, The wide-bandgap perovskite material includes FA. 0.8 Cs 0.2 Pb(I 0.62 Br 0.38 3. FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 3. FA 0.15 Cs 0.85 Pb(I 0.73 Br 0.27 3. Cs 0.12 MA 0.05 FA 0.83 Pb(I 0.6 Br 0.4 )3 and FA 0.2 Cs 0.8 Pb(I 0.67 Br 0.33 One or more of 3.

18. The tandem solar cell according to any one of claims 15 to 17, wherein, The narrow bandgap perovskite material satisfies the chemical formula: Y2Pb 1-d2 Sn d2 I3, Y2 includes Cs + , FA + , MA + , and Rb + one or more of, 0.2≤d2≤0.

7.

19. The laminated solar cell of claim 18, wherein, The narrow bandgap perovskite material includes MA 0.3 FA 0.7 Pb 0.5 Sn 0.5 I3, MAPb 0.85 Sn 0.15 I3, FAPb 0.5 Sn 0.5 I3 and FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 One or more of I3.

20. The tandem solar cell according to any one of claims 15 to 19, wherein, One or more of the following conditions must be met: (1) The band gap of the wide bandgap perovskite material is 1.6 eV to 2.0 eV; (2) The band gap of the narrow band gap perovskite material is 1.2eV to 1.4eV.

21. The tandem solar cell according to any one of claims 1 to 20, wherein The stacked solar cell further includes: First electrode and second electrode; The first light-absorbing layer is disposed between the first electrode and the first interface layer, and the second light-absorbing layer is disposed between the second interface layer and the second electrode.

22. The laminated solar cell of claim 21, wherein, One of the first electrode and the second electrode is a transparent electrode.

23. The tandem solar cell of claim 21 or 22, wherein, The stacked solar cell further includes: First charge transport layer and second charge transport layer; The first charge transport layer is disposed between the first electrode and the first light-absorbing layer, and the second charge transport layer is disposed between the second light-absorbing layer and the second electrode.

24. The laminated solar cell of claim 23, wherein, One of the first charge transport layer and the second charge transport layer is an electron transport layer, and the other is a hole transport layer.

25. The laminated solar cell of claim 24, wherein, The first charge transport layer is a hole transport layer, and the second charge transport layer is an electron transport layer.

26. A method for preparing a tandem solar cell, comprising: A first light-absorbing layer, a composite layer, and a second light-absorbing layer are formed, with the composite layer located between the first light-absorbing layer and the second light-absorbing layer, to prepare the stacked solar cell; The composite layer includes a first interface layer and a second interface layer, which are disposed between the first interface layer and the second light-absorbing layer. The first interface layer comprises an N-type semiconductor, the second interface layer comprises a P-type semiconductor, the N-type semiconductor comprises an N-type perovskite material, and / or the P-type semiconductor comprises a P-type perovskite material.

27. A photovoltaic module comprising a tandem solar cell according to any one of claims 1 to 25 or a tandem solar cell prepared by the method of claim 26.

28. An electrical device comprising one or more of the following: a tandem solar cell according to any one of claims 1 to 25, a tandem solar cell prepared by the method of claim 26, and a photovoltaic module according to claim 27.

29. A power generation device comprising one or more of the tandem solar cells according to any one of claims 1 to 25, the photovoltaic module according to claim 26, and the photovoltaic module according to claim 27.

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