Laminated solar cell, photovoltaic system, power generation device, and power utilization device

Abstract

The invention provides a laminated solar cell, a photovoltaic system, a power generation device and a power utilization device. The laminated solar cell comprises a first electrode, a first light absorption layer, a first charge extraction layer, an upper conversion layer, a second charge extraction layer, a second light absorption layer and a second electrode which are sequentially laminated along a first direction; one of the first charge extraction layer and the second charge extraction layer is a hole transport layer, and the other one is an electron transport layer; the upconversion layer includes an upconversion material. In the laminated solar cell, holes and electrons extracted by the first charge extraction layer and the second charge extraction layer can be compounded in the upper conversion layer, energy generated by compounding of the holes and the electrons can be accumulated in the upper conversion layer under the action of the upper conversion material, and finally photons with energy higher than that of the holes and the electrons are radiated. Photons generated by radiation of the upper conversion layer can be absorbed again by the first light absorption layer and the second light absorption layer, and then the light current of the laminated solar cell is increased.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a tandem solar cell, a photovoltaic system, a power generation device, and a power consumption device. Background Technology

[0002] Solar cells convert solar energy into electrical energy, making them relatively environmentally friendly. Photocurrent is a crucial performance indicator for solar cells. Developing tandem solar cells is an effective way to improve their photocurrent. Although tandem solar cells can achieve higher photocurrents compared to single solar cells, further increasing the photocurrent of tandem solar cells remains significant. Summary of the Invention

[0003] This application provides a first aspect of a tandem solar cell. The tandem solar cell includes a first electrode, a first light-absorbing layer, a first charge extraction layer, an upconversion layer, a second charge extraction layer, a second light-absorbing layer, and a second electrode, which are sequentially stacked along a first direction; one of the first charge extraction layer and the second charge extraction layer is a hole transport layer and the other is an electron transport layer; the upconversion layer comprises an upconversion material.

[0004] In the aforementioned tandem solar cell, the holes and electrons extracted by the first and second charge extraction layers can recombine in the upper conversion layer. Under the action of the upper conversion material, the energy generated by the recombination of holes and electrons can accumulate in the upper conversion layer, eventually radiating photons with energy higher than that of holes and electrons. The photons radiated by the upper conversion layer can be reabsorbed by the first and second light-absorbing layers, thereby increasing the photocurrent of the tandem solar cell.

[0005] In some embodiments, the upconversion material includes an electro-induced upconversion material. Electro-induced upconversion materials can promote the accumulation of energy generated by the recombination of holes and electrons, promote the generation of high-energy photons, and further increase the photocurrent of the tandem solar cell.

[0006] In some embodiments, the upconversion material includes phthalocyanine. Phthalocyanine can convert low-energy charges into high-energy photons, which can make full use of the low-energy charges generated by the tandem solar cell, further improving the light utilization efficiency of the tandem solar cell and further increasing the photocurrent of the tandem solar cell.

[0007] In some embodiments, the upper conversion layer includes a conductive layer, an intermediate layer, and an upper conversion material layer sequentially stacked along the first direction; the upper conversion material layer contains the upper conversion material; the intermediate layer contains a material with the chemical formula MZ, wherein M includes one or more of Li, Na, K, Rb, and Cs, and Z includes one or more of F, Cl, Br, and I. Z ions in the intermediate layer can act as a charge transfer medium, promoting the transfer of charge received by the conductive layer to the upper conversion material layer, promoting the recombination and energy accumulation of holes and electrons in the upper conversion layer, improving the utilization rate of energy generated by hole and electron recombination, and further increasing the photocurrent of the tandem solar cell. Simultaneously, the intermediate layer can buffer the energy band between the conductive layer and the upper conversion material layer, further promoting the recombination and energy accumulation of holes and electrons in the upper conversion layer, thereby further increasing the photocurrent of the tandem solar cell. In some embodiments, the conductive layer contains one or more of gold, silver, fluorine-doped tin oxide, indium tin oxide, zinc aluminum oxide, boron-doped zinc oxide, indium zinc oxide, and indium tungsten oxide.

[0008] In some embodiments, the thickness of the conductive layer is 1 nm to 2 nm.

[0009] In some embodiments, the thickness of the intermediate layer is 0.2 nm to 2 nm.

[0010] In some embodiments, the thickness of the upconversion material layer is 15 nm to 25 nm. A thickness within this range allows the tandem solar cell to achieve a high upconversion efficiency while maintaining a suitable thickness, further improving the utilization rate of energy generated by hole-electron recombination and increasing the photocurrent of the tandem solar cell.

[0011] In some embodiments, the band gap of the first light-absorbing layer is different from that of the second light-absorbing layer. The use of a first light-absorbing layer and a second light-absorbing layer with different band gaps can absorb light of different wavelengths, thereby improving the light utilization efficiency of the tandem solar cell and increasing the photocurrent of the tandem solar cell.

[0012] In some embodiments, the band gap of the first light-absorbing layer is larger than that of the second light-absorbing layer. During the fabrication of the top conversion layer, the influence of the top conversion material layer on the light-absorbing layer may be greater than that of the conductive layer. In the fabrication process of a tandem solar cell, the fabrication of the light-absorbing layer with a wider band gap typically precedes that of the light-absorbing layer with a narrower band gap; that is, the first light-absorbing layer is fabricated first, followed by the second. In this case, in the top conversion layer, the conductive layer is closer to the first light-absorbing layer than the top conversion material layer; that is, the conductive layer is fabricated before the top conversion material layer. This allows the influence of the top conversion material layer on the first light-absorbing layer to be reduced, which helps maintain a more stable structure in the first light-absorbing layer and further improves the photocurrent of the tandem solar cell.

[0013] In some embodiments, the band gap of the first light-absorbing layer is 1.6 eV to 2.2 eV.

[0014] In some embodiments, the band gap of the second light-absorbing layer is 1 eV to 1.4 eV.

[0015] In some embodiments, the stacked solar cell further includes a third charge extraction layer; the third charge extraction layer is located between the first electrode and the first light-absorbing layer; one of the third charge extraction layer and the first charge extraction layer is a hole transport layer and the other is an electron transport layer.

[0016] In some embodiments, the tandem solar cell further includes a fourth charge extraction layer; the fourth charge extraction layer is located between the second electrode and the second light-absorbing layer; one of the fourth charge extraction layer and the second charge extraction layer is a hole transport layer and the other is an electron transport layer.

[0017] In some embodiments, the first light-absorbing layer includes one or more of a perovskite light-absorbing layer and a silicon-based light-absorbing layer.

[0018] In some embodiments, the second light-absorbing layer includes one or more of a perovskite light-absorbing layer and a silicon-based light-absorbing layer.

[0019] A second aspect of this application provides a photovoltaic system. The photovoltaic system includes the tandem solar cells of the first aspect.

[0020] A third aspect of this application provides a power generation device. The power generation device includes a tandem solar cell as described in the first aspect.

[0021] A fourth aspect of this application provides an electrical device comprising a tandem solar cell as described in the first aspect. Attached Figure Description

[0022] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a stacked solar cell according to one embodiment of this application.

[0024] Explanation of markings in the diagram:

[0025] 10. Tandem solar cell; 101. First electrode; 102. First light-absorbing layer; 103. First charge extraction layer; 104. Upper conversion layer; 1041. Conductive layer; 1042. Intermediate layer; 1043. Upper conversion material layer; 105. Second charge extraction layer; 106. Second light-absorbing layer; 107. Second electrode; 108. Third charge extraction layer; 109. Fourth charge extraction layer.

[0026] To better describe and illustrate embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the currently described embodiments and / or examples, or the best mode of these inventions as currently understood. Detailed Implementation

[0027] Hereinafter, some embodiments of this application are disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0028] 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.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0030] The "range" disclosed in this application is defined by 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 and can be arbitrarily combined; that is, 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 also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are 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 "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 "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0033] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, and in some embodiments, they are performed sequentially. For example, the method includes steps (a) and (b), indicating 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), indicating that step (c) may 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.

[0034] Unless otherwise specified, in this application, the term "room temperature" generally refers to 4°C to 30°C, and preferably 25±5°C.

[0035] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art. For example, they can be tested according to the methods given in the embodiments of this application.

[0036] In the structural design of solar cells, tandem solar cells can achieve higher photocurrents compared to single solar cells. In traditional tandem solar cells, metal layers or transparent conductive layers are typically used to connect adjacent solar cells. In this case, holes and electrons generated by adjacent solar cells will recombine in the metal layer or transparent conductive layer. The energy generated by this recombination is often lost in the form of low-energy photons and heat, and is difficult to reuse.

[0037] Based on this, please refer to Figure 1 This application provides a tandem solar cell 10 according to one embodiment. The tandem solar cell 10 includes a first electrode 101, a first light-absorbing layer 102, a first charge extraction layer 103, an upconversion layer 104, a second charge extraction layer 105, a second light-absorbing layer 106, and a second electrode 107, sequentially stacked along a first direction. One of the first charge extraction layer 103 and the second charge extraction layer 105 is a hole transport layer, and the other is an electron transport layer. The upconversion layer contains an upconversion material. Figure 1 In the diagram, the arrow indicates the first direction.

[0038] It is understood that upconversion materials are materials that can convert low-energy light into high-energy light. In the tandem solar cell 10 of this embodiment, the upconversion material can convert the energy generated by the recombination of holes and electrons into photons of higher energy. The higher-energy photons are reabsorbed by the first light-absorbing layer 102 and the second light-absorbing layer 106, thereby reusing the energy generated by the recombination of holes and electrons. Specifically, in the tandem solar cell 10 of this embodiment, the holes and electrons extracted by the first charge extraction layer 103 and the second charge extraction layer 105 can recombine in the upconversion layer 104. Under the action of the upconversion material, the energy generated by the recombination of holes and electrons can accumulate in the upconversion layer 104, and finally radiate photons with energy higher than that of holes and electrons. The photons radiated by the upconversion layer 104 can be reabsorbed by the first light-absorbing layer 102 and the second light-absorbing layer 106, thereby increasing the photocurrent of the tandem solar cell.

[0039] In some embodiments, the upconversion material includes an electro-induced upconversion material. The electro-induced upconversion material can promote the accumulation of energy generated by the recombination of holes and electrons, promote the generation of high-energy photons, and further increase the photocurrent of the tandem solar cell 10. For example, in the tandem solar cell 10, under the action of the electro-induced upconversion material, the energy generated by the recombination of holes and electrons can accumulate in the upconversion layer 104, ultimately radiating photons with a wavelength of 600 nm. These photons can be reabsorbed by the first light-absorbing layer 102 and the second light-absorbing layer 106 located on both sides of the upconversion layer 104, thereby increasing the photocurrent of the tandem solar cell 10.

[0040] Optionally, the upconversion material includes phthalocyanine. For example, for longer wavelength infrared light, the energy of the charge generated by the light-absorbing layer is very small, and this low-energy charge is more easily dissipated. For instance, for infrared light with a wavelength of 1200 nm, the energy of the charge generated by the light-absorbing layer is very small, and this low-energy charge is easily dissipated and difficult to reuse. In this case, phthalocyanine can convert this low-energy charge into higher-energy photons, thus making full use of the low-energy charge generated by the tandem solar cell, which can further improve the light utilization rate of the tandem solar cell and further increase the photocurrent of the tandem solar cell.

[0041] Please refer to it again. Figure 1 In some embodiments, the upper conversion layer 104 includes a conductive layer 1041, an intermediate layer 1042, and an upper conversion material layer 1043 sequentially stacked along a first direction. The upper conversion material layer 1043 contains an upper conversion material. The intermediate layer 1042 contains a material with the chemical formula MZ, wherein M includes one or more of Li, Na, K, Rb, and Cs, and Z includes one or more of F, Cl, Br, and I. The conductive layer 1041 can promote the transport of holes or electrons, and the Z ions in the intermediate layer 1042 can act as a charge transfer medium, promoting the transfer of charges received by the conductive layer 1043 to the upper conversion material layer 1041, promoting the recombination of holes and electrons in the upper conversion layer, thereby promoting the accumulation of energy generated by recombination, improving the utilization rate of energy generated by hole and electron recombination, and further increasing the photocurrent of the tandem solar cell 10. Meanwhile, the intermediate layer 1042 can buffer the energy band between the conductive layer 1043 and the upper conversion material layer 1041, further promoting the recombination of holes and electrons in the upper conversion layer, thereby further increasing the photocurrent of the tandem solar cell 10.

[0042] Optionally, the conductive layer 1041 can be prepared by sputtering, the intermediate layer 1042 can be prepared by vapor deposition, and the upper conversion material layer 1043 can be prepared by vapor deposition.

[0043] Optionally, the intermediate layer 1042 comprises one or more of LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr, and CsI. Optionally, the thickness of the intermediate layer 1042 is 0.2 nm to 2 nm. For example, the thickness of the intermediate layer 1042 can be 0.2 nm, 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, 2 nm, or any value within the range of any two of the above values.

[0044] In some embodiments, the conductive layer 1041 comprises one or more of gold, silver, fluorine-doped tin oxide, indium tin oxide, zinc aluminum oxide, boron-doped zinc oxide, indium zinc oxide, and indium tungsten oxide. Optionally, the thickness of the conductive layer 1041 is 1 nm to 2 nm. For example, the thickness of the conductive layer 1041 can be 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2 nm, or any value within the range of any two of the above values.

[0045] In some embodiments, the thickness of the upconversion material layer 1043 is 15 nm to 25 nm. A thickness within this range allows the tandem solar cell 10 to achieve a high upconversion efficiency while maintaining a suitable thickness, further improving the utilization rate of energy generated by hole-electron recombination and increasing the photocurrent of the tandem solar cell. Optionally, the thickness of the upconversion material layer 1043 can be 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, or any value within the range of any two of the above values.

[0046] Understandably, the upper conversion layer 104 and other layers in the tandem solar cell 10 can be identified by slicing the tandem solar cell sample and analyzing the cross-section of the sliced ​​sample. Simultaneously, the composition of the different layer structures can be confirmed using elemental analysis methods.

[0047] In some embodiments, the band gap of the first light-absorbing layer 102 is different from that of the second light-absorbing layer 106. The use of the first light-absorbing layer 102 and the second light-absorbing layer 106 with different band gaps can absorb light of different wavelengths, thereby improving the light utilization efficiency of the tandem solar cell 10 and increasing the photocurrent of the tandem solar cell 10.

[0048] In some embodiments, the band gap of the first light-absorbing layer 102 is larger than that of the second light-absorbing layer 106. When fabricating the upper conversion layer 104, the upper conversion material layer 1041 may have a greater impact on the light-absorbing layer than the conductive layer 1043. In the fabrication process of the tandem solar cell 10, the fabrication of the light-absorbing layer with a wider band gap usually precedes the fabrication of the light-absorbing layer with a narrower band gap; that is, the first light-absorbing layer 102 is fabricated first, followed by the second light-absorbing layer 106. In this case, in the upper conversion layer 104, the conductive layer 1043 is closer to the first light-absorbing layer 102 than the upper conversion material layer 1041, meaning the conductive layer 1043 is fabricated before the upper conversion material layer 1041. This allows the conductive layer 1043 to be fabricated first, reducing the impact of the upper conversion material layer 1041 on the first light-absorbing layer 102, which helps maintain a more stable structure of the first light-absorbing layer 102 and further improves the photocurrent of the tandem solar cell 10.

[0049] Optionally, the band gap of the first light-absorbing layer 102 is 1.6 eV to 2.2 eV. For example, the band gap of the first light-absorbing layer 102 can be 1.6 eV, 1.7 eV, 1.8 eV, 1.9 eV, 2 eV, 2.1 eV, 2.2 eV, or any value within the range of any two of the above values.

[0050] Optionally, the band gap of the second light-absorbing layer 106 is 1 eV to 1.4 eV. For example, the band gap of the second light-absorbing layer 106 can be 1 eV, 1.1 eV, 1.2 eV, 1.3 eV, 1.4 eV, or any value within the range of any two of the above values.

[0051] In some embodiments, the first charge extraction layer 103 is an electron transport layer, and the second charge extraction layer 105 is a hole transport layer. The upper conversion layer 104 includes a conductive layer 1041, an intermediate layer 1042, and an upper conversion material layer 1043 stacked together. The upper conversion material layer 1043 is located between the second charge extraction layer 105 and the intermediate layer 1042.

[0052] In some embodiments, the first charge extraction layer 103 is a hole transport layer, and the second charge extraction layer 105 is an electron transport layer. The upper conversion layer 104 includes a conductive layer 1041, an intermediate layer 1042, and an upper conversion material layer 1043 stacked together. The upper conversion material layer 1043 is located between the second charge extraction layer 105 and the intermediate layer 1042.

[0053] In some embodiments, the tandem solar cell 10 further includes a third charge extraction layer 108. The third charge extraction layer 108 is located between the first electrode 101 and the first light-absorbing layer 102. Of the third charge extraction layer 108 and the first charge extraction layer 103, one is a hole transport layer and the other is an electron transport layer.

[0054] In some embodiments, the tandem solar cell 10 further includes a fourth charge extraction layer 109. The fourth charge extraction layer 109 is located between the second electrode 107 and the second light-absorbing layer 106. Of the fourth charge extraction layer 109 and the second charge extraction layer 105, one is a hole transport layer and the other is an electron transport layer.

[0055] In some embodiments, the first light-absorbing layer 102 includes one or more of the following: a perovskite light-absorbing layer, a silicon-based light-absorbing layer, a cadmium telluride light-absorbing layer, a gallium arsenide light-absorbing layer, and a copper indium gallium selenide (CIGS) light-absorbing layer. The second light-absorbing layer 106 includes one or more of the following: a perovskite light-absorbing layer, a silicon-based light-absorbing layer, a cadmium telluride light-absorbing layer, a gallium arsenide light-absorbing layer, and a CIGS light-absorbing layer. By selecting the light-absorbing layer, different types of tandem solar cells 10 can be obtained. For example, perovskite-perovskite tandem solar cells, perovskite-crystalline silicon tandem solar cells, perovskite-heterojunction tandem solar cells, crystalline silicon-crystalline silicon tandem solar cells, and heterojunction-heterojunction tandem solar cells. It is understood that the tandem solar cell can be a two-layer, three-layer, four-layer, or more-layer tandem cell. Furthermore, in the tandem solar cell, the connection method between the sub-cells can be parallel or series connection.

[0056] Optionally, the perovskite light-absorbing layer comprises a material with the chemical formula ABX3 or A2CDX6. Wherein:

[0057] A is an inorganic, organic, or mixed organic-inorganic cation, comprising at least one of organic amine cations, Cs cations, K cations, Rb cations, and Li cations; the organic amine cation is selected from (NR1R2R3R4). + (R1R2N=CR3R4) + (R1R2N-C(R5)=NR3R4) + Or (R1R2N-C(NR5R6)=R3R4) + R1, R2, R3, R4, R5, and R6 are each independently selected from H, substituted or unsubstituted C1-20 alkyl groups, or substituted or unsubstituted aryl groups; A is optionally methylamino (CH3NH3) + (MA) + ), formamidinyl (HC(NH2)2 + (FA) + ), cesium ions (Cs + ) and rubidium (Rb + At least one of the following, further optionally methylamino (CH3NH3) + ) or formamidinyl (HC(NH2)2 + ).

[0058] B is an inorganic, organic, or mixed organic-inorganic cation, including at least one of lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium, and optionally a divalent metal ion Pb. 2+ and Sn 2+ At least one of them.

[0059] C is an inorganic, organic, or mixed organic-inorganic cation, optionally a monovalent metal ion Ag. + wait.

[0060] D is an inorganic, organic, or mixed organic-inorganic cation, optionally a trivalent metal ion bismuth cation Bi. 3+ Antimony cation Sb 3+ Indium cations In 3+ wait.

[0061] X is an inorganic, organic, or mixed organic-inorganic anion, optionally one or more of a halide anion and a halide-like anion, and further optionally a bromide ion (Br). - ) or iodide ions (I - ).

[0062] In some embodiments, the thickness of the perovskite light-absorbing layer is 100 nm to 1000 nm. Optionally, the thickness of the perovskite light-absorbing layer can be, but is not limited to, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, and any two of the above values.

[0063] In some embodiments, the band gap of the perovskite absorbing layer is 1 eV to 2.3 eV. As an example, the band gap of the perovskite absorbing layer is 1 eV, 1.1 eV, 1.2 eV, 1.3 eV, 1.4 eV, 1.5 eV, 1.6 eV, 1.7 eV, 1.8 eV, 1.9 eV, 2 eV, 2.1 eV, 2.2 eV, 2.3 eV, or any two of the above values. When the band gap of the perovskite absorbing layer is within the above range, it can exhibit high visible light absorption efficiency.

[0064] For the tandem solar cell 10, the material of the first electrode 101 includes one or more of organic conductive materials, inorganic conductive materials, and organic-inorganic mixed conductive materials. Optionally, the material of the first electrode 101 includes one or more of transparent conductive metal oxides, carbon, metals, and their alloys. For example, the material of the first electrode 101 includes one or more of indium tin oxide (ITO), lanthanide-doped indium oxide, fluorine-doped tin oxide (FTO), antimony-doped tin oxide, boron-doped zinc oxide (BZO), zinc aluminum oxide (AZO), indium zinc oxide (IZO), zinc gallium oxide (GZO), indium tungsten oxide (IWO), Au and its alloys, Ag and its alloys, Cu and its alloys, Al and its alloys, Ni and its alloys, Cr and its alloys, Bi and its alloys, Pt and its alloys, Mg and its alloys, Mo and its alloys, W and its alloys, graphite, graphene, and carbon nanotubes. Optionally, the thickness of the first electrode 101 is 100 nm to 1000 nm. For example, the thickness of the first electrode 101 can be 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, or any value within the range of any two of the above values. Further optionally, the thickness of the first electrode 101 can be 300nm to 800nm. Optionally, the first electrode 101 can be a transparent electrode. It is understood that the transparent electrode layer refers to the electrode on the light-incident side of the tandem solar cell 10.

[0065] For the tandem solar cell 10, the material of the second electrode 107 includes at least one of a conductive metal, a conductive non-metal, and a conductive oxide. Optionally, the conductive metal is selected from at least one of Au, Ag, Cu, Al, Ni, Cr, Bi, Pt, Mg, Mo, W, and their alloys. The conductive non-metal is selected from C. The conductive oxide includes at least one of indium tin oxide (ITO), lanthanide-doped indium oxide, fluorine-doped tin oxide (FTO), zinc aluminum oxide (AZO), boron-doped zinc oxide (BZO), and indium zinc oxide (IZO). Optionally, the thickness of the second electrode 107 is not particularly limited, and electrode thicknesses conventional in the art, such as 20 nm to 200 nm, can be used. For example, the thickness of the second electrode 107 is 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, or any value within the range of any two of the above values. Optionally, the thickness of the second electrode 107 is 60nm to 100nm, and more preferably, the thickness of the second electrode 107 is 70nm to 90nm. More preferably, the second electrode 107 is a back electrode.

[0066] It is understood that the tandem solar cell 10 also includes a substrate. A first electrode 101 can be formed on the substrate. The substrate includes a glass substrate and a flexible substrate. The material of the flexible substrate may be, but is not limited to, organic polymer materials. Further, the material of the flexible substrate may be a mixture of one or more of the following materials in different proportions: including but not limited to polyvinyl alcohol (PVA), polyethylene terephthalate (PET), polyimide (PI), polyethylene dinaphthalate (PEN), polydimethylsiloxane (PDMS), etc.

[0067] In the case of the tandem solar cell 10, the charge extraction layer can be either a hole transport layer or an electron transport layer.

[0068] Optionally, the material of 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), methoxytriphenylamine-fluoroformamidinium, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), poly3-hexylthiophene (P3HT) The following are some of the following: triphenylamine with a triphenylene core (H101), 3,4-ethylenedioxythiophene-methoxytriphenylamine (EDOT-OMeTPA), N-(4-aniline)carbazole-spirobisfluorene (CzPAF-SBF), polythiophene, phosphate monomolecule, carbazole monomolecule, sulfonic acid monomolecule, triphenylamine monomolecule, aromatic monomolecule, metal oxide, cuprous iodide and cuprous thiocyanate, wherein the metal element in the metal oxide may include one or more of Ni, Mo and Cu.

[0069] Optionally, the material of 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-fluoroformamidine (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-spirobisfluorene (CzPAF-SBF), polythiophene, metal oxides, silicon oxide (SiO2), strontium titanate (SrTiO3), cuprous thiocyanate (CuSCN), copper bath ether (BCP), etc. The metallic elements may include one or more of Mg, Ni, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

[0070] It is understandable that other functional layers, such as modification layers, can be introduced into the tandem solar cell 10 as needed. Optionally, the tandem solar cell 10 can be provided with modification layers of appropriate energy levels, which can play one or more of the following roles: lowering the energy level barrier, promoting energy level matching, improving carrier extraction efficiency, passivating interface defect states, protecting the light absorption layer, suppressing the oxidation and decomposition of the cell by water molecules and oxygen, improving photoelectric conversion efficiency, and improving the stability of the perovskite cell. Depending on the location of the modification layer, the type of modification layer may include a modification layer between the hole transport layer and the first electrode 101, a modification layer between the electron transport layer and the second electrode 107, a modification layer between the hole transport layer and the light-absorbing layer, and a modification layer between the electron transport layer and the light-absorbing layer. Materials that can be used for modification layers in the tandem solar cell 10 may include, but are not limited to, Cu2O, NiO, AZO, TiO2, etc.

[0071] In some embodiments, the tandem solar cell 10 further includes a metal fluoride layer. The metal fluoride layer is located between the electron transport layer and the second electrode 107. Alternatively, the metal fluoride layer is located between the electron transport layer and the first electrode 101. The presence of the metal fluoride layer can promote electron extraction, thereby improving the photoelectric conversion efficiency of the perovskite photovoltaic module.

[0072] Please refer to it again. Figure 1In some embodiments, the tandem solar cell 10 includes a first electrode 101, a hole transport layer (i.e., a third charge extraction layer 108), a first light-absorbing layer 102, an electron transport layer (i.e., a first charge extraction layer 103), a conductive layer 1041, an intermediate layer 1042, an upper conversion material layer 1043, a hole transport layer (i.e., a second charge extraction layer 105), a second light-absorbing layer 106, an electron transport layer (i.e., a fourth charge extraction layer 109), and a second electrode 107, which are stacked sequentially. The first light-absorbing layer 102 and the second light-absorbing layer 106 are both perovskite light-absorbing layers.

[0073] Another embodiment of this application provides a photovoltaic system. The photovoltaic system includes the above-described tandem solar cell 10.

[0074] Another embodiment of this application provides a power generation device. The power generation device includes the above-described tandem solar cell 10.

[0075] Another embodiment of this application provides an electrical device. The electrical device includes the above-described stacked solar cell 10.

[0076] In some embodiments, the aforementioned tandem solar cell 10 can be a power generation device for an electrical device. 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 of a vehicle, the back panel, etc.

[0077] Furthermore, the aforementioned electrical devices may include mobile devices, such as mobile phones and laptops, electric vehicles, electric trains, ships and satellites, power generation systems, etc., but are not limited to these.

[0078] 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.

[0079] 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.

[0080] Example 1

[0081] The method for preparing the tandem solar cell 10 in this embodiment is as follows:

[0082] S101: Clean the ITO conductive glass sequentially with acetone, alcohol, and deionized water, and then dry it.

[0083] S102: Add [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphoric acid (MeO-4PACz) to an ethanol solvent and stir. Spin-coat the ethanol solution of MeO-4PACz onto a conductive glass at a spin speed of 4000 rpm for 30 s. Then transfer it to a hot plate and anneal at 100 °C for 10 min to form a hole transport layer (i.e., the third charge extraction layer 108).

[0084] S103: 3 mg FAI, 59 mg FABr, 46 mg CsI, 25 mg CsBr, 428 mg PbI2, and 209 mg PbBr2 were added to 1 mL of a mixture of DMF and DMSO (DMF to DMSO volume ratio 3:1). The mixture was stirred at 600 rpm for 8 hours using a magnetic stirrer, filtered, and the perovskite precursor solution was obtained. 100 μL of the perovskite precursor solution was spin-coated onto the hole transport layer obtained in S102. Spin-coating conditions: First, spin-coating at 2000 rpm and 200 rpm / s for 10 s, then spin-coating at 4000 rpm and 1000 rpm / s for 25 s. Then, 200 μL of chlorobenzene was added dropwise to the spin-coated perovskite precursor solution. Next, the perovskite precursor solution was spin-coated at 4000 rpm for 15 seconds. Then, it was transferred to a hot stage and annealed at 100°C for 15 minutes to form the first light-absorbing layer 102.

[0085] S104: A 20 nm SnO2 layer is prepared on the first light-absorbing layer 102 obtained in S103 using atomic layer deposition (ALD) to form an electron transport layer (i.e., the first charge extraction layer 103).

[0086] S105: A gold layer with a thickness of 1 nm (i.e., conductive layer 1041) is sputtered onto the electron transport layer obtained in S104. Then, a NaCl layer with a thickness of 0.5 nm (i.e., intermediate layer 1042) is deposited on the Au layer. Phthalocyanine is then deposited on the NaCl layer to form a phthalocyanine layer with a thickness of 20 nm (i.e., upper conversion material layer 1043).

[0087] S106: Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was spin-coated onto the phthalocyanine layer obtained in S105 at a spin speed of 4000 rpm for 30 s. Then, it was transferred to a hot stage and annealed at 150 °C for 10 min to form a hole transport layer (i.e., the second charge extraction layer 105).

[0088] S107: 2 mg of CH(NH2)2I, 85 mg of CH3NH2I, 4 mg of PbI2, 335 mg of SnI2, and 0.5 mg of MeO-4PACz were added to 1 mL of a mixture of DMF and DMSO (DMF to DMSO volume ratio 3:1). The mixture was stirred at 600 rpm for 2 h on a magnetic stirrer, filtered, and a perovskite precursor solution was obtained. 100 μL of the perovskite precursor solution was spin-coated onto the hole transport layer obtained in S106. The spin-coating conditions were: first, spin-coating at 1000 rpm and 200 rpm / s for 10 s, then spin-coating at 3000 rpm and 1000 rpm / s for 20 s. Then, 350 μL of ethyl acetate was added dropwise to the spin-coated perovskite precursor solution. Next, the perovskite precursor solution was spin-coated at 4000 rpm for 20 seconds. Then, it was transferred to a hot stage and annealed at 100°C for 10 minutes to form the second light-absorbing layer 106.

[0089] S108: A 10 nm thick copper bath (BCP) is deposited on the second light-absorbing layer 106 obtained in S107 to form an electron transport layer (i.e., the fourth charge extraction layer 109).

[0090] S109: A copper layer with a thickness of 100 nm is deposited on the electron transport layer obtained in S108 to form the second electrode 107. The tandem solar cell 10 is obtained.

[0091] Comparative Example 1

[0092] Compared with Example 1, the fabrication method of the tandem solar cell in Comparative Example 1 is as follows:

[0093] S201~S204: Same as S101~S104 in Example 1.

[0094] S205: An ITO conductive layer with a thickness of 20 nm is prepared on the electron transport layer obtained in S204 by magnetron sputtering.

[0095] S206: Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is spin-coated onto the ITO conductive layer obtained in S205 at a spin speed of 4000 rpm for 30 s. Then, it is transferred to a hot stage and annealed at 150 °C for 10 min to form a hole transport layer (i.e., the second charge extraction layer).

[0096] S207~S209: Same as S107~S109 in Example 1.

[0097] Test case

[0098] The photocurrent and photoelectric conversion efficiency of the tandem solar cells obtained in the examples and comparative examples were tested. The test method was as follows: a solar simulator and an IV meter were used to test the photocurrent and photoelectric conversion efficiency of the tandem solar cells. The conditions of the solar simulator were: a total irradiance of 100 mW / cm². 2 The battery temperature was 25℃, and the spectral distribution was AM1.5G. The results are shown in Table 1.

[0099]

[0100] As can be seen from Table 1, the tandem solar cell in Example 1 has higher photocurrent and photoelectric conversion efficiency than the tandem solar cell in Comparative Example 1, indicating that the setting of the upper conversion layer in Example 1 is beneficial to improving the photocurrent and photoelectric conversion efficiency of the tandem solar cell.

[0101] 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.

[0102] The embodiments described above are merely illustrative of several 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, characterized in that, It includes a first electrode, a first light-absorbing layer, a first charge extraction layer, an upconversion layer, a second charge extraction layer, a second light-absorbing layer, and a second electrode, which are stacked sequentially along a first direction; one of the first charge extraction layer and the second charge extraction layer is a hole transport layer and the other is an electron transport layer; the upconversion layer contains an upconversion material.

2. The tandem solar cell according to claim 1, characterized in that, The upconversion material includes an electro-induced upconversion material.

3. The tandem solar cell according to claim 1 or 2, characterized in that, The upconversion material includes phthalocyanine.

4. The tandem solar cell according to any one of claims 1 to 3, characterized in that, The upper conversion layer includes a conductive layer, an intermediate layer, and an upper conversion material layer stacked sequentially along the first direction; the upper conversion material layer contains the upper conversion material; the intermediate layer contains a material with the chemical formula MZ, wherein M includes one or more of Li, Na, K, Rb, and Cs, and Z includes one or more of F, Cl, Br, and I.

5. The tandem solar cell according to claim 4, characterized in that, The conductive layer comprises one or more of the following: gold, silver, fluorine-doped tin oxide, indium tin oxide, zinc aluminum oxide, boron-doped zinc oxide, indium zinc oxide, and indium tungsten oxide.

6. The tandem solar cell according to claim 4 or 5, characterized in that, The thickness of the conductive layer is 1 nm to 2 nm.

7. The tandem solar cell according to any one of claims 4 to 6, characterized in that, The thickness of the intermediate layer is 0.2nm to 2nm.

8. The tandem solar cell according to any one of claims 4 to 7, characterized in that, The thickness of the upper conversion material layer is 15nm~25nm.

9. The tandem solar cell according to any one of claims 4 to 8, characterized in that, The band gap of the first light-absorbing layer is different from that of the second light-absorbing layer.

10. The tandem solar cell according to any one of claims 4 to 9, characterized in that, The band gap of the first light-absorbing layer is larger than that of the second light-absorbing layer.

11. The tandem solar cell according to claim 9 or 10, characterized in that, The band gap of the first light-absorbing layer is 1.6 eV to 2.2 eV; and / or, The band gap of the second light-absorbing layer is 1eV to 1.4eV.

12. The tandem solar cell according to any one of claims 1 to 11, characterized in that, The stacked solar cell further includes a third charge extraction layer; the third charge extraction layer is located between the first electrode and the first light-absorbing layer; of the third charge extraction layer and the first charge extraction layer, one is a hole transport layer and the other is an electron transport layer.

13. The tandem solar cell according to any one of claims 1 to 12, characterized in that, The tandem solar cell further includes a fourth charge extraction layer; the fourth charge extraction layer is located between the second electrode and the second light-absorbing layer; of the fourth charge extraction layer and the second charge extraction layer, one is a hole transport layer and the other is an electron transport layer.

14. The tandem solar cell according to any one of claims 1 to 13, characterized in that, The first light-absorbing layer includes one or more of a perovskite light-absorbing layer and a silicon-based light-absorbing layer; and / or, The second light-absorbing layer includes one or more of a perovskite light-absorbing layer and a silicon-based light-absorbing layer.

15. A photovoltaic system, characterized in that, The tandem solar cell includes any one of claims 1 to 14.

16. A power generation device, characterized in that, The tandem solar cell includes any one of claims 1 to 14.

17. An electrical device, characterized in that, The tandem solar cell includes any one of claims 1 to 14.

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