Stacked solar cell and method of manufacturing the same

Abstract

The embodiment of the invention belongs to the technical field of solar cells, and mainly relates to a laminated solar cell and a preparation method thereof. The laminated solar cell comprises a first sub-cell, a middle connecting layer and a second sub-cell which are laminated in sequence, wherein the middle connecting layer comprises a first connecting layer and a second connecting layer, a plurality of first microstructures are arranged on one surface, close to the second connecting layer, of the first connecting layer, and a plurality of second microstructures are arranged on one surface, close to the first connecting layer, of the second connecting layer; the first microstructures and the second microstructures are arranged in a staggered mode, and the first connecting layer makes contact with the second connecting layer through the first microstructures and the second microstructures. According to the laminated solar cell in the technical scheme, the interface contact area and the binding force between the middle connecting layers can be enhanced, and reliable connection between the film layers is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cells, and in particular, relates to a stacked solar cell and a preparation method thereof. Background Art

[0002] At present, perovskite single-junction solar cells have a high efficiency, but in order to further improve the efficiency of the cells, it is necessary to vigorously develop perovskite tandem solar cells. In the preparation process of tandem solar cells, the lamination method can circumvent the material stability problems caused by solvent orthogonality and vacuum thin film deposition. However, one of the current challenges of the lamination method in preparing tandem devices is the interface compatibility of the connecting layers between the sub-cells. Poor interface contact will affect the mechanical strength and flexibility of the intermediate connecting layer.

[0003] In order to improve the interface compatibility of the connecting layer between sub-batteries, some researchers have achieved good intermediate layer connection by developing high viscosity or organic intermediate layers that can undergo cross-linking reactions, wet film processing, increasing thickness, etc. However, high viscosity or cross-linked intermediate layers will reduce conductivity and increase the series resistance of the battery; wet film processing will leave solvents in the bulk phase, affecting the structural stability of the intermediate layer; increasing the film thickness will affect the effective recombination of electrons and holes in the intermediate layer, while increasing the series resistance of the battery, resulting in a decrease in open circuit voltage and fill factor.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The embodiment of the present application provides a stacked solar cell and a method for preparing the same to solve or alleviate the above technical problems. The stacked solar cell in the technical solution of the present application can enhance the interface contact area and bonding force between the intermediate connection layers and achieve reliable connection between the film layers.

[0006] In a first aspect, an embodiment of the present application provides a stacked solar cell, comprising: a first sub-cell, an intermediate connection layer, and a second sub-cell stacked in sequence; Among them, the intermediate connecting layer includes a first connecting layer and a second connecting layer, the first connecting layer has a plurality of first microstructures on a side close to the second connecting layer, the second connecting layer has a plurality of second microstructures on a side close to the first connecting layer, the first microstructures and the second microstructures are alternately arranged, and the first connecting layer and the second connecting layer are in contact with each other through the first microstructures and the second microstructures.

[0007] Optionally, the material of the first connecting layer is one or more of n-type metal oxide, fullerene and fullerene derivatives, perylene diimide and its derivatives, and azo-poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole]; The material of the second connecting layer is one or more of a second p-type metal oxide, a π-conjugated polymer, a heterocyclic small molecule electron donor material, and an electron donor material having ultraviolet light cross-linking.

[0008] Optionally, the n-type metal oxide includes one or more of zinc oxide, titanium oxide, indium tin oxide, gallium oxide, indium gallium zinc oxide, tin oxide, chromium oxide and lanthanum oxide.

[0009] Optionally, the fullerene and fullerene derivatives include: one or more of fullerene C60, fullerene C70, [6,6]-phenyl-C61-butyric acid isomethyl ester, [6,6]-phenyl-C71-butyric acid isomethyl ester, 1',1'',4',4''-tetrahydrodi[1,4]methylenenaphthalene [2',3':1,2;2'',3'':56,60][5,6]fullerene-C60-IH, ICMA, bis

[60] PCBM, tris

[60] PCBM.

[0010] Optionally, the perylene diimide and its derivatives include: one or more of perylene diimide, bromoperylene diimide, triphenylamine-substituted perylene diimide, naphthalene diimide, azo-thiophene-benzothiadiazole-perylene diimide, and azido-perylene diimide.

[0011] Optionally, the p-type metal oxide includes one or more of nickel oxide, copper oxide, cobalt oxide, vanadium oxide and iron oxide.

[0012] Optionally, the π-conjugated polymer includes: poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, poly(3-hexylthiophene), poly(p-phenylene), polydithiophene-pyrrolodione-3,6-dithiophene, poly(4,8-dithiophene-2,6-diyl-3,7-dithiophene)-4,4'-dienylbenzene, poly[4,8-dithiophene-2,6-diyl-3,7-dithiophene]-2,5-dipyridine, poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole], poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole-2,3-difluorophenyl].

[0013] Optionally, the heterocyclic small molecule electron donor material includes one or more of 5,6,11,12-tetraphenylanthracene, dithienopyrrolodione, benzothiophene-triphenylamine, tetrafluorobenzothiophene, DPP-4-thiophene, DPP-thiophene-difluorobenzene, DDP-2-thiophene, and DPP-benzothiadiazole.

[0014] Optionally, the electron donor material with ultraviolet light cross-linking includes: one or more of azo-poly (3-hexylthiophene), azo-PTB7, azo-ITIC, fluorinated PBDB-T, and fluorinated PTB7.

[0015] Optionally, the thickness of the intermediate connection layer is 40nm-200nm; and / or The thickness of the first connecting layer is 20nm-100nm; and / or The thickness of the second connecting layer is 20nm-100nm.

[0016] In a second aspect, an embodiment of the present application provides a method for preparing a stacked solar cell, comprising: providing a first sub-cell and a second sub-cell; A first connection layer is formed on one side of the first sub-cell; a first microstructure is provided on a side of the first connection layer away from the first sub-cell, A second connection layer is formed on one side of the second sub-cell; and a second microstructure is provided on a side of the second connection layer away from the second sub-cell; The first connection layer and the second connection layer are in contact with each other through the first microstructure and the second microstructure, and together form an intermediate connection layer; the first microstructure and the second microstructure are arranged alternately; The first sub-cell, the first connection layer, the second connection layer and the second sub-cell are closely contacted by adopting a lamination process.

[0017] Optionally, the lamination process includes one of a hot pressing process, a cold pressing process, a vacuum lamination process, a solvent lamination process, and an ultraviolet light curing lamination process.

[0018] The above technical solution adopted in the embodiment of the present application may have the following advantages: In the stacked solar cell of the embodiment of the present application, the intermediate connection layer includes a first connection layer having a plurality of first microstructures and a second connection layer having a plurality of second microstructures, and the first microstructure and the second microstructure are arranged alternately with each other, which can enhance the interface contact area and bonding force between the intermediate connection layers, realize the reliable connection between the film layers, thereby reducing the edge loss or effective area loss caused by the relative sliding between the film layers during the lamination process. In addition, the first microstructure and the second microstructure can not only reduce the compressive stress, but also reduce the structural or morphological changes of the pressure-sensitive active layer during the processing, thereby improving the yield rate. Moreover, in the traditional lamination process, it is generally necessary to provide a temperature above 80°C to allow chemical crosslinking or physical bonding between the intermediate layers, but the glass transition temperature of some organic intermediate layers or active layers is lower than 80°C, and segment movement may occur during the processing process, thereby reducing the optoelectronic performance. The microstructure design proposed in the present application can increase the interface contact area and bonding force, and can make the intermediate layer firmly contact without heating, broadening the selectivity of lamination technology in stacked materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0020] Figure 1 is a schematic structural diagram of a stacked solar cell provided by an embodiment of the present application; Figure 2 is a schematic diagram of the structure of an intermediate connection layer provided by an embodiment of the present application; Figures 3a to 3d is a schematic structural diagram of a first microstructure and a second microstructure provided in an embodiment of the present application; Figure 4 It is a schematic diagram of the structure of a stacked solar cell provided in another embodiment of the present application.

[0021] Description of reference numerals: 100, first sub-cell; 200, intermediate connection layer; 210, first connection layer; 211, first microstructure; 220, second connection layer; 221, second microstructure; 300, second sub-cell, 400, third sub-cell; 500, first electrode; 600, second electrode; G1, first gap; G2, second gap. DETAILED DESCRIPTION

[0022] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0023] like Figures 1 to 4 As shown, the embodiment of the present application provides a stacked solar cell, comprising: a first sub-cell 100, an intermediate connection layer 200, and a second sub-cell 300 stacked in sequence; Among them, the intermediate connecting layer 200 includes a first connecting layer 210 and a second connecting layer 220. The first connecting layer 210 has a plurality of first microstructures 211 on a surface close to the second connecting layer 220, and the second connecting layer 220 has a plurality of second microstructures 221 on a surface close to the first connecting layer 210. The first microstructures 211 and the second microstructures 221 are arranged alternately with each other, and the first connecting layer 210 and the second connecting layer 220 are in contact with each other through the first microstructures 211 and the second microstructures 221.

[0024] During the lamination process, the conventional intermediate connection layer will slide before the sub-cell. In the laminated solar cell of the embodiment of the present application, the intermediate connection layer includes a first connection layer having a plurality of first microstructures and a second connection layer having a plurality of second microstructures, and the first microstructure and the second microstructure are arranged alternately with each other, which can enhance the interface contact area and bonding force between the intermediate connection layers, realize the reliable connection between the film layers, thereby reducing the edge loss or effective area loss caused by the relative sliding between the film layers during the lamination process. In addition, the first microstructure and the second microstructure can not only reduce the compressive stress, but also reduce the structural or morphological changes of the pressure-sensitive active layer during the processing, thereby improving the yield rate. Moreover, in the traditional lamination process, it is generally necessary to provide a temperature above 80°C to allow chemical crosslinking or physical bonding between the intermediate layers, but the glass transition temperature of some organic intermediate layers or active layers is lower than 80°C, and segment movement may occur during the processing process, thereby reducing the optoelectronic performance. The microstructure design proposed in the present application can increase the interface contact area and bonding force, and the intermediate layer can be firmly contacted without heating, broadening the selectivity of lamination technology in laminated materials.

[0025] It should be noted that in the embodiments of the present application, Figure 2As shown, there is a first gap G1 between two adjacent first microstructures 211 , a second gap G2 between two adjacent second microstructures 221 , the first microstructure 211 is located in the second gap G2 , and the second microstructure 221 is located in the first gap G1 , so that the first microstructure 211 and the second microstructure 221 are alternately arranged.

[0026] It should also be noted that, in the embodiment of the present application, the interface between the first sub-battery and the intermediate connection layer is firmly connected, and the interface between the second sub-battery and the intermediate connection layer is also firmly connected.

[0027] In an optional embodiment, multiple first microstructures form an array, that is, the multiple first microstructures are regularly arranged along the row direction and / or column direction; multiple second microstructures form an array, that is, the multiple second microstructures are regularly arranged along the row direction and / or column direction; this can improve the parallelism and integration of the structure and facilitate production operations.

[0028] In some embodiments, the material of the first connection layer is one or more of n-type metal oxide, fullerene and fullerene derivatives, perylene diimide and its derivatives, and azo-poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole]; The material of the second connection layer is one or more of p-type metal oxide, π-conjugated polymer, heterocyclic small molecule electron donor material, and electron donor material with ultraviolet light cross-linking.

[0029] In the embodiment of the present application, the material of the first connecting layer and the material of the second connecting layer are two semiconductor materials with opposite polarities, one of which is an electron donor material for conducting electrons, and the other is an electron acceptor material for conducting holes. In addition, the material of the first connecting layer and the material of the second connecting layer are in close contact with each other through physical action (e.g., van der Waals force) or chemical action (e.g., cross-linking reaction).

[0030] In the present application, n-type metal oxides, fullerenes and fullerene derivatives, perylene diimide and its derivatives, and azo-poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole] are capable of extracting and conducting electrons from the active layer, and as the material of the first connecting layer, they can be bonded with the material of the second connecting layer.

[0031] In the present application, p-type metal oxides, π-conjugated polymers, heterocyclic small molecule electron donor materials, and electron donor materials with UV crosslinking can extract and conduct holes from the active layer, and as the material of the second connecting layer, they can be bonded with the material of the first connecting layer.

[0032] In some embodiments, the n-type metal oxide includes zinc oxide (ZnO), titanium oxide (TiO 2)、Indium Tin Oxide (ITO), Gallium Oxide (Ga 2 O 3 ), indium gallium zinc oxide (IGZO), tin oxide (SnO 2 ), chromium oxide (Cr 2 O 3 ) and lanthanum oxide (La 2 O 3 )

[0033] In some embodiments, fullerenes and fullerene derivatives include: fullerene C 60 , Fullerene C 70 、[6,6]-phenyl-C61-butyric acid isomethyl ester (

[60] PCBM), [6,6]-phenyl-C71-butyric acid isomethyl ester (

[70] PCBM), 1',1'',4',4''-tetrahydrodi[1,4]methylenenaphthalene [2',3':1,2;2'',3'':56,60][5,6]fullerene-C 60 -IH (ICBA), ICMA (CAS No.: 186682-36-0), bis

[60] PCBM (bis-PCBM), tris

[60] PCBM (tris-PCBM) or one or more thereof.

[0034] In some embodiments, perylene diimide and its derivatives include: one or more of perylene diimide (PDI), bromoperylene diimide (Br-PDI), triphenylamine-substituted perylene diimide (TPA-PDI), naphthalene diimide (NDI), azo-thiophene-benzothiadiazole-perylene diimide, and azido-perylene diimide.

[0035] In some embodiments, the p-type metal oxide includes nickel oxide (NiO), copper oxide (CuO x ), cobalt oxide (CoO), vanadium oxide (V 2 O 5 ) and iron oxide (Fe 2 O 3 )

[0036] In some embodiments, the π-conjugated polymer includes one or more of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (PEDOT:PSS (PH1000)), poly(3-hexylthiophene), poly(p-phenylene glycol), poly(dithienopyrrolodione-3,6-dithiophene), poly(4,8-dithiophene-2,6-diyl-3,7-dithiophene)-4,4'-dienylbenzene (PM6), poly[4,8-dithiophene-2,6-diyl-3,7-dithiophene]-2,5-diylpyridine (PTQ10), poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole] (PBDB-T), and poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole-2,3-difluorophenyl] (PBDB-T-SF).

[0037] In some embodiments, the heterocyclic small molecule electron donor material includes one or more of 5,6,11,12-tetraphenylanthracene, bithienopyrrolodione, benzothiophene-triphenylamine, tetrafluorobenzothiophene, DPP-4-thiophene, DPP-thiophene-difluorobenzene, DDP-2-thiophene, and DPP-benzothiadiazole.

[0038] In some embodiments, the electron donor material with UV crosslinking includes one or more of azo-poly(3-hexylthiophene), azo-PTB7, azo-ITIC, fluorinated PBDB-T, and fluorinated PTB7.

[0039] In some embodiments, the thickness of the intermediate connecting layer is 40 nm-200 nm; and / or The thickness of the first connecting layer is 20nm-100nm; and / or The thickness of the second connection layer is 20nm-100nm.

[0040] If the thickness of the first connection layer and / or the second connection layer is less than 20 nm, it is technically difficult to prepare a microstructure on its surface. If the thickness of the first connection layer and / or the second connection layer is greater than 100 nm, the series resistance of the stacked solar cell will increase.

[0041] In an optional embodiment, if Figures 3a to 3d As shown, the shapes of the first microstructure 211 and the second microstructure 221 can be cone, column or hemisphere respectively.

[0042] like Figure 3a and Figure 3b As shown, the cone refers to the first microstructure or the second microstructure having different cross-sectional areas at different heights, and the cross-sectional area gradually decreases or increases along the height direction, wherein the cross-sectional area at the top may be 0 or may not be 0. Figure 3cAs shown in FIG. 1 , a column refers to a first microstructure or a second microstructure in which the cross-sections at different heights have the same area. Figure 3d As shown, the hemisphere refers to a curved surface structure in the first microstructure or the second microstructure. When the first microstructure and the second microstructure are in the shape of a cone, a column or a hemisphere, the roughness of the interface between the first connection layer and the second connection layer can be increased, which is conducive to preventing relative sliding between the first connection layer and the second connection layer.

[0043] In an optional embodiment, the cone includes a cone (circular in cross section), an elliptical cone (elliptical in cross section), a triangular cone (triangular in cross section) or a quadrilateral cone (quadrilateral in cross section); The cylinder includes a circular cylinder (circular in cross section), an elliptical cylinder (elliptical in cross section), a triangular cylinder (triangular in cross section) or a quadrilateral cylinder (quadrilateral in cross section).

[0044] In an optional embodiment, the stacked solar cell can be a double-junction cell, a triple-junction cell or a multi-junction cell; when the stacked solar cell is a triple-junction cell or a multi-junction cell, there are three or more sub-cells, and there is an intermediate connection layer including a first connection layer and a second connection layer between each two adjacent sub-cells.

[0045] In an optional embodiment, the sub-cells (eg, first sub-cells, second sub-cells) include: crystalline silicon cells, amorphous silicon cells, Group III-V semiconductor cells, Group II-VI semiconductor cells, organic-inorganic hybrid perovskite cells, organic solar cells, and quantum dot cells.

[0046] In an optional embodiment, the crystalline silicon cell includes but is not limited to: a passivated emitter and rear (PERC) cell, a TOPCon cell, a heterojunction (HJT) cell, and a back contact cell. In an optional embodiment, the organic-inorganic hybrid perovskite material is ABX 3 Crystal structure, wherein the A position includes but is not limited to amine materials such as methylamine and formamidine, the B position includes but is not limited to divalent metal ions such as lead and tin, and the X position includes but is not limited to halogen elements. In an optional embodiment, the III-V semiconductor includes but is not limited to: compounds composed of gallium, indium, arsenic, and phosphorus. In an optional embodiment, the II-VI semiconductor includes but is not limited to: compounds composed of cadmium, tellurium, zinc, magnesium, copper, indium, and selenium. In an optional embodiment, the organic solar cell includes but is not limited to: bulk heterojunction battery, planar heterojunction battery. In an optional embodiment, the quantum dot battery includes but is not limited to: lead sulfide, cadmium sulfide, cadmium selenide, copper indium sulfide and other compounds.

[0047] In an optional embodiment, a stacked solar cell may include three or more sub-cells stacked in sequence, with an intermediate connection layer between each two adjacent sub-cells; wherein each intermediate connection layer includes a corresponding first connection layer and a second connection layer; in the corresponding first connection layer and second connection layer, a first connection layer has a plurality of first microstructures on a side close to the second connection layer, and a second connection layer has a plurality of second microstructures on a side close to the first connection layer, the first microstructures and the second microstructures are arranged alternately with each other, and the first connection layer and the second connection layer are in contact with each other through the first microstructures and the second microstructures. Specifically, as Figure 4 As shown, the stacked solar cell includes a first sub-cell 100, a second sub-cell 300, and a third sub-cell 400 located between the first sub-cell 100 and the second sub-cell 300; wherein, the intermediate connection layer 200 described in the embodiment of the present application is provided between the first sub-cell 100 and the third sub-cell 400, and between the second sub-cell 300 and the third sub-cell 400.

[0048] In an optional embodiment, if Figure 1 and Figure 4 As shown, the stacked solar cell further includes a first electrode 500 located on a side of the first sub-cell 100 away from the intermediate connection layer 200 , and a second electrode 600 located on a side of the second sub-cell 300 away from the intermediate connection layer 200 .

[0049] In an optional embodiment, the first electrode includes a substrate and a transparent conductive oxide layer; the substrate may be a rigid substrate or a flexible substrate (polyethylene terephthalate, polyimide, polymethyl methacrylate, polyparaxylene, polyethylene naphthalene, etc.); the transparent conductive oxide layer on the rigid substrate includes one or more of indium tin oxide, indium zinc oxide, aluminum zinc oxide, gallium tin oxide, cadmium tin oxide, and fluorine-doped tin oxide; the transparent conductive oxide layer on the rigid substrate includes one or more of indium tin oxide, silver nanowires, graphene, carbon nanotubes, and conductive polymers (such as PEDOT).

[0050] The present application provides a method for preparing a stacked solar cell, comprising: S100: providing a first sub-battery and a second sub-battery; S200: forming a first connection layer on one side of the first sub-cell; the first connection layer having a first microstructure on a side away from the first sub-cell, S300: forming a second connection layer on one side of the second sub-cell; the second connection layer having a second microstructure on a side away from the second sub-cell; S400: making the first connection layer and the second connection layer contact each other through the first microstructure and the second microstructure to form an intermediate connection layer together; the first microstructure and the second microstructure are arranged alternately; S500: Using a lamination process to bring the first sub-cell, the first connection layer, the second connection layer and the second sub-cell into close contact.

[0051] In an optional embodiment, in step S200, forming a first connection layer on one side of the first sub-cell includes: S210: depositing a material of a first connection layer on one side of the first sub-cell to form an initial first connection layer; S220: Using one of nanoimprinting, 3D printing, evaporation, etching, physical vapor deposition, chemical vapor deposition, and atomic layer vapor deposition to form a first microstructure on the surface of the initial first connection layer to form a first connection layer.

[0052] It should be noted that in step S220, when the material of the first connecting layer is an n-type metal oxide, the first microstructure is formed by etching, physical vapor deposition, chemical vapor deposition or atomic layer vapor deposition; when the material of the first connecting layer is fullerene and fullerene derivatives, perylene diimide and its derivatives, or azo-poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole], the first microstructure is formed by nanoimprinting, 3D printing or evaporation.

[0053] In an optional embodiment, in step S300, forming a second connection layer on one side of the second sub-cell includes: S310: depositing a material of a second connection layer on one side of the second sub-cell to form an initial second connection layer; S320: forming a second microstructure on the surface of the initial second connection layer by using one of nanoimprinting, 3D printing, evaporation, etching, physical vapor deposition, chemical vapor deposition, and atomic layer vapor deposition to form a second connection layer.

[0054] It should be noted that in step S320, when the material of the second connecting layer is a p-type metal oxide, the second microstructure is formed by etching, physical vapor deposition, chemical vapor deposition or atomic layer vapor deposition; when the material of the second connecting layer is a π-conjugated polymer, a heterocyclic small molecule electron donor material, or an electron donor material with ultraviolet light cross-linking, the second microstructure is formed by nanoimprinting, 3D printing or evaporation.

[0055] Photolithography has the advantages of high precision and large-area uniformity, can achieve submicron or even nanometer resolution, is suitable for the preparation of fine microstructures, and is widely used in the semiconductor industry with mature processes. Nanoimprinting technology is known for its low cost and simple process, is suitable for large-scale production, can use a variety of materials, and achieve highly repeatable consistent nanostructures. 3D printing technology provides extremely high design flexibility, can manufacture complex geometries, is suitable for personalized and small-batch production, and has low material waste. Etching technology can selectively remove materials, achieve high selectivity and good surface finish, which is suitable for the needs of optoelectronic devices, and can be used in combination with other manufacturing processes to adjust the shape of the structure. Physical vapor deposition (PVD) is known for its high-quality films and good adhesion, and is suitable for the deposition of various materials, especially in intermediate layers with strict thickness requirements. Chemical vapor deposition (CVD) can uniformly deposit thin films on substrates of complex shapes, has versatility and adjustable film properties, and is suitable for high-temperature and low-temperature deposition. Atomic layer vapor deposition (ALD) provides atomic-level thickness control and excellent uniformity, can deposit high-quality films on complex substrates, and is suitable for low-temperature deposition of heat-sensitive materials.

[0056] In some embodiments, the lamination process includes one of a hot pressing process, a cold pressing process, a vacuum lamination process, a solvent lamination process, and an ultraviolet light curing lamination process.

[0057] The hot pressing process improves the contact between the perovskite layer and the middle layer by heating and applying pressure, making the interface between the layers tighter, thereby reducing the interface resistance and improving the charge transfer efficiency. The cold pressing process applies pressure at a lower temperature, which is gentler on heat-sensitive perovskite materials and avoids decomposition caused by high temperature. At the same time, it can improve the tightness between the layers and reduce charge recombination losses. The vacuum lamination process is to perform lamination under a vacuum environment, which can reduce the oxygen and moisture contact between the perovskite and the middle layer, thereby improving the stability of the perovskite and extending the life of the device; the vacuum can also eliminate bubbles between the interfaces and enhance the interface bonding. The solvent lamination process uses an appropriate solvent to soften or dissolve the surface of the middle layer to form a better interface bonding, which helps to improve the interface charge transfer efficiency and reduce interface defects. The UV curing lamination process is a curing reaction triggered by ultraviolet light, which allows the middle layer to form a stable interface structure, reduce migration, and enhance the durability and long-term stability of the perovskite battery.

[0058] In an optional embodiment, the steps of the UV curing lamination process include: Selecting a polymer or small molecule material containing an ultraviolet light initiator (such as a material containing styrene, acrylate, azo or azide groups) as the photosensitive material to ensure that the material of the first connecting layer and / or the material of the second connecting layer can be cross-linked and cured under ultraviolet light; The photosensitive material is evenly coated on the side of the first connection layer away from the first sub-cell or the side of the second connection layer away from the second sub-cell by spin coating, scraper coating, spray coating or dip coating to form a photosensitive layer; wherein the thickness of the photosensitive layer is 10-100nm; this is because a too thick photosensitive layer may lead to incomplete photocuring, while a too thin photosensitive layer may reduce the interlayer bonding effect; Align the upper substrate to be laminated onto the photosensitive layer and ensure good contact between the layers; Use a UV LED lamp, mercury lamp, or high-pressure UV lamp, and select the appropriate wavelength (common wavelengths are 365nm or 254nm) and intensity (e.g., 10-100mW / cm 2 ), irradiate for 30 seconds to 5 minutes to ensure complete light curing; the temperature is controlled at room temperature or low temperature (such as 20-40℃) to avoid degradation of the perovskite layer caused by high temperature.

[0059] In an optional embodiment, the step of the UV light curing lamination process further includes: annealing at 80-100° C. for 10-15 minutes after the UV light curing is complete, which can further enhance the interlayer bonding effect.

[0060] In an optional embodiment, when forming the photosensitive layer, if the photosensitive material contains a solvent, it is necessary to pre-dry at 50-70° C. to remove the residual solvent and prevent the solvent from affecting the perovskite light-absorbing layer or causing bubbles.

[0061] In an optional embodiment, after lamination is completed, the lamination quality can be checked by optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), etc. to ensure that there are no bubbles, cracks or delamination.

[0062] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0063] Example 1 like Figure 1 to Figure 2 and Figure 3a As shown, the structure of the stacked solar cell of Embodiment 1 comprises: a first sub-cell 100, an intermediate connection layer 200, and a second sub-cell 300 stacked in sequence; The intermediate connection layer 200 includes a first connection layer 210 and a second connection layer 220. The first connection layer 210 has a first microstructure 211 on one side close to the second connection layer 220. The second connection layer 220 has a second microstructure 221 on one side close to the first connection layer 210. The shape of the first microstructure 211 matches the shape of the second microstructure 221. The first connection layer 210 and the second connection layer 220 are in contact with each other through the first microstructure 211 and the second microstructure 221. The first microstructure 211 and the second microstructure 221 are both in the shape of a pyramid; The material of the first connection layer is tin oxide, and the material of the second connection layer is PEDOT:PSS (PH1000).

[0064] The method for preparing the stacked solar cell of embodiment 1 comprises: S100a: providing a first sub-battery and a second sub-battery; S200a: forming a first connection layer on one side of the first sub-cell; the first connection layer having a first microstructure on a side away from the first sub-cell, S300a: forming a second connection layer on one side of the second sub-cell; the second connection layer having a second microstructure on a side away from the second sub-cell; S400a: making the first connection layer and the second connection layer contact each other through the first microstructure and the second microstructure to form an intermediate connection layer together; the first microstructure and the second microstructure are arranged alternately; S500a: Using a lamination process, the first sub-cell, the first connection layer, the second connection layer and the second sub-cell are brought into close contact.

[0065] Example 2-18 The structure and preparation method of the stacked solar cells of Examples 2-18 are similar to the structure and preparation method of the stacked solar cells of Example 1, and the only difference is that the material of the first connecting layer, the material of the second connecting layer, and the shapes of the first microstructure and the second microstructure are different. The material of the first connecting layer, the material of the second connecting layer, and the shapes of the first microstructure and the second microstructure in Examples 2-18 are shown in Table 1.

[0066] Table 1

[0067] Table 1 (continued)

[0068] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also points out the stacked solar cell of Comparative Example 1.

[0069] Comparative Example 1 The structure of the stacked solar cell of Comparative Example 1 comprises: a first sub-cell, an intermediate connection layer, and a second sub-cell stacked in sequence; The middle connection layer is a structure with a smooth surface, and the materials of the middle connection layer are tin oxide and PEDOT:PSS (PH1000).

[0070] The present application also uses photovoltaic modules made of the stacked solar cells of Examples 1 to 18 of the present application, and performs performance tests on the corresponding photovoltaic modules to obtain the open circuit voltage Voc, short circuit current density Jsc, fill factor FF, and photoelectric conversion efficiency PCE of the corresponding battery devices. The test results are shown in Table 2.

[0071] Table 2

[0072] It can be seen from the data in Table 2 that, compared with Comparative Example 1, the fill factor and conversion efficiency of the photovoltaic modules made of the stacked solar cells of Examples 1 to 18 of the present application are significantly improved, and the short-circuit current and open-circuit voltage are also slightly improved.

[0073] In summary, in the laminated solar cell of the embodiment of the present application, the intermediate connection layer includes a first connection layer having a plurality of first microstructures and a second connection layer having a plurality of second microstructures, and the first microstructure and the second microstructure are arranged alternately with each other, which can enhance the interface contact area and bonding force between the intermediate connection layers, realize the reliable connection between the film layers, thereby reducing the edge loss or effective area loss caused by the relative sliding between the film layers during the lamination process. In addition, the first microstructure and the second microstructure can not only reduce the compressive stress, but also reduce the structural or morphological changes of the pressure-sensitive active layer during the processing, thereby improving the yield rate. Moreover, in the traditional lamination process, it is generally necessary to provide a temperature above 80°C to allow chemical crosslinking or physical bonding between the intermediate layers, but the glass transition temperature of some organic intermediate layers or active layers is lower than 80°C, and segment movement may occur during the processing process, thereby reducing the optoelectronic performance. The microstructure design proposed in the present application can increase the interface contact area and bonding force, and the intermediate layer can be firmly contacted without heating, broadening the selectivity of lamination technology in laminated materials.

[0074] The embodiment of the present application provides a photovoltaic module (not shown), comprising the stacked solar cell of any of the above embodiments. The photovoltaic module also has the advantages of the above stacked solar cell, which will not be described in detail here.

[0075] The embodiment of the present application can provide a photovoltaic system, including the photovoltaic components in the above embodiment. The advantages of the above photovoltaic components are also possessed by the photovoltaic system, which will not be repeated here. The above photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0076] It should be noted that, in order to more clearly illustrate the technical solution of the present application, there is a certain gap between the layers in the drawings of the present application, but the layers in the actual stacked solar cells are in contact with each other, and the layers of the stacked solar cells are in close contact with each other through external stress.

[0077] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0078] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0079] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0080] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0081] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A stacked solar cell, characterized in that: include: A first sub-cell, an intermediate connection layer, and a second sub-cell stacked in sequence; Among them, the intermediate connecting layer includes a first connecting layer and a second connecting layer, the first connecting layer has a plurality of first microstructures on a side close to the second connecting layer, the second connecting layer has a plurality of second microstructures on a side close to the first connecting layer, the first microstructures and the second microstructures are alternately arranged, and the first connecting layer and the second connecting layer are in contact with each other through the first microstructures and the second microstructures.

2. The stacked solar cell according to claim 1, characterized in that: The material of the first connection layer is one or more of n-type metal oxide, fullerene and fullerene derivatives, perylene diimide and its derivatives, and azo-poly[6,6'-(2,5-dithiophene)-2,5'-benzothiadiazole]; The material of the second connection layer is one or more of p-type metal oxide, π-conjugated polymer, heterocyclic small molecule electron donor material, and electron donor material with ultraviolet light cross-linking.

3. The stacked solar cell according to claim 2, characterized in that: The n-type metal oxide includes one or more of zinc oxide, titanium oxide, indium tin oxide, gallium oxide, indium gallium zinc oxide, tin oxide, chromium oxide and lanthanum oxide.

4. The stacked solar cell according to claim 2, characterized in that: The fullerene and fullerene derivatives include: fullerene C 60 , Fullerene C 70 、[6,6]-phenyl-C61-butyric acid isomethyl ester、[6,6]-phenyl-C71-butyric acid isomethyl ester、1',1'',4',4''-tetrahydrodi[1,4]methylenenaphthalene[2',3':1,2;2'',3'':56,60][5,6]fullerene-C 60 - One or more of IH, ICMA, dual [60] PCBM, and triple [60] PCBM.

5. The stacked solar cell according to claim 2, characterized in that: The perylene diimide and its derivatives include: one or more of perylene diimide, bromoperylene diimide, triphenylamine-substituted perylene diimide, naphthalene diimide, azo-thiophene-benzothiadiazole-perylene diimide and azido-perylene diimide.

6. The stacked solar cell according to claim 2, characterized in that: The p-type metal oxide includes one or more of nickel oxide, copper oxide, cobalt oxide, vanadium oxide and iron oxide.

7. The stacked solar cell according to claim 2, characterized in that: The π-conjugated polymer includes: one or more of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, poly(3-hexylthiophene), poly(p-phenylene glycol), polybithiophene-pyrrolodione-3,6-bithiophene, poly(4,8-bithiophene-2,6-diyl-3,7-bithiophene)-4,4'-dienylbenzene, poly[4,8-bithiophene-2,6-diyl-3,7-bithiophene]-2,5-diylpyridine, poly[6,6'-(2,5-bithiophene)-2,5'-benzothiadiazole], and poly[6,6'-(2,5-bithiophene)-2,5'-benzothiadiazole-2,3-difluorophenyl].

8. The stacked solar cell according to claim 2, characterized in that: The heterocyclic small molecule electron donor material includes one or more of 5,6,11,12-tetraphenylanthracene, bithienopyrrolodione, benzothiophene-triphenylamine, tetrafluorobenzothiophene, DPP-4-thiophene, DPP-thiophene-difluorobenzene, DDP-2-thiophene, and DPP-benzothiadiazole.

9. The stacked solar cell according to claim 2, characterized in that: The electron donor material with ultraviolet light cross-linking includes: one or more of azo-poly (3-hexylthiophene), azo-PTB7, azo-ITIC, fluorinated PBDB-T, and fluorinated PTB7.

10. The stacked solar cell according to any one of claims 1 to 9, characterized in that: The thickness of the intermediate connecting layer is 40nm-200nm; and / or The thickness of the first connecting layer is 20nm-100nm; and / or The thickness of the second connecting layer is 20nm-100nm.

11. A method for preparing a stacked solar cell, characterized in that: include: providing a first sub-cell and a second sub-cell; forming a first connection layer on one side of the first sub-cell; The first connection layer has a first microstructure on a surface away from the first sub-cell, A second connection layer is formed on one side of the second sub-cell; and a second microstructure is provided on a side of the second connection layer away from the second sub-cell; The first connecting layer and the second connecting layer are in contact with each other through the first microstructure and the second microstructure, and together form an intermediate connecting layer; The first microstructure and the second microstructure are arranged alternately; The first sub-cell, the first connection layer, the second connection layer and the second sub-cell are closely contacted by adopting a lamination process.

12. The method for preparing a stacked solar cell according to claim 11, characterized in that: The lamination process includes one of a hot pressing process, a cold pressing process, a vacuum lamination process, a solvent lamination process, and an ultraviolet light curing lamination process.

Images