Laminated solar cell and preparation method thereof

Abstract

The invention discloses a laminated solar cell and a preparation method thereof, the laminated solar cell comprises a bottom cell, a top cell and a tunneling composite layer located between the bottom cell and the top cell, the tunneling composite layer comprises multiple sub tunneling layers, and the multiple sub tunneling layers have different work functions. According to the laminated solar cell structure, a multi-layer tunneling composite layer structure with different work function combinations is formed between the bottom cell and the top cell, so that a composite barrier of carriers between the top cell and the bottom cell is slowed down, and effective recombination of the carriers is promoted; the open-circuit voltage, the short-circuit current density and the photoelectric conversion efficiency of the laminated solar cell are effectively improved, and the problem that the open-circuit voltage, the short-circuit current density and the photoelectric conversion efficiency are low due to the fact that the laminated solar cell adopts a single tunneling composite layer in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the field of solar cells, and in particular, to a stacked solar cell and a method for preparing the same. Background Art

[0002] Perovskite Solar Cells (PSCs) are a new type of solar cell with great development potential and have attracted much attention since their first appearance. Among them, semi-transparent perovskite solar cells have attracted extensive attention and research because they can perform energy conversion while also having decorative effects, and perovskite / silicon two-terminal stacked solar cells have high photoelectric conversion efficiency.

[0003] The tunneling recombination layer is the key to preparing high-efficiency perovskite / silicon two-terminal stacked solar cells. Its main function is to form an electrical connection between the perovskite top cell and the crystalline silicon bottom cell, effectively recombine electrons and holes with minimal resistance loss, and ensure high optical transparency in the long-wave band.

[0004] Transparent Conductive Oxide (TCO) thin films have broad application prospects in thin-film solar cells due to their low resistivity and high transmittance in the visible light range. In particular, in the field of perovskite solar cells, TCO thin films are often used as transparent electrodes and tunneling composite layer materials. Currently, the TCO materials used as tunneling composite layers mainly include tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium hydroxide (In2O3:H), zinc-doped tin oxide (ZTO), zirconium-doped indium oxide (IZrO), etc. The tunneling composite layer connects the top cell and the bottom cell in series in the stacked solar cell. When the cell receives light, electrons and holes jump and transfer in the tunneling composite layer to produce a recombination effect. At present, the industry generally uses magnetron sputtering to prepare a single-layer TCO structure as a tunneling composite layer. The single-layer tunneling composite layer has the same energy level barrier, and there is resistance to the transfer of electrons and holes, which in turn affects the recombination effect of electrons and holes, resulting in low open circuit voltage, short circuit current density and photoelectric conversion efficiency of the stacked solar cell. Summary of the invention

[0005] The present application provides a stacked solar cell and a preparation method thereof, so as to solve the problem that the stacked solar cell in the prior art uses a single tunneling composite layer, resulting in low open circuit voltage, short circuit current density and photoelectric conversion efficiency.

[0006] According to one aspect of the present application, a stacked solar cell is provided, comprising: a bottom cell, a top cell and a tunneling composite layer located between the bottom cell and the top cell, wherein the tunneling composite layer comprises a plurality of sub-tunneling layers, and the plurality of sub-tunneling layers have different work functions.

[0007] Optionally, the sub-tunneling layer in contact with the bottom battery has a work function that is a first work function, and the work functions of the remaining sub-tunneling layers are all greater than the first work function and increase in a direction perpendicular to the bottom battery.

[0008] Optionally, the material of each of the sub-tunneling layers includes transparent conductive oxide.

[0009] Optionally, the transparent conductive oxide material includes one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO).

[0010] Optionally, the transparent conductive oxide materials of each sub-tunneling layer are different.

[0011] Optionally, the thickness of each sub-tunneling layer is 5 nm to 80 nm.

[0012] According to another aspect of the present application, a method for preparing a stacked solar cell is provided, comprising: providing a bottom cell; forming a tunneling composite layer on the front side of the bottom cell; wherein the tunneling composite layer comprises a plurality of sub-tunneling layers, the plurality of sub-tunneling layers having different work functions; and forming a top cell on a surface of the tunneling composite layer facing away from the bottom cell.

[0013] Optionally, the step of forming the tunneling composite layer includes: using multiple deposition processes to form a plurality of sub-tunneling layers on the front side of the bottom battery, in which a gas containing argon and oxygen is used as a raw material gas, the flow rate of the argon is 30 sccm to 400 sccm, the flow rate of the oxygen is 0.1 sccm to 20 sccm, the reaction pressure is 0.1 Pa to 1 Pa, and the reaction temperature is 25°C to 230°C.

[0014] Optionally, a different flow rate of the argon gas and a different flow rate of the oxygen gas are used in each deposition process, and a different reaction pressure is used in each deposition process.

[0015] Optionally, the vacuum degree at the start of each deposition process is less than 1×10 -4 Pa, the DC power applied to the target during the deposition process is 10W ~ 500W.

[0016] Through the technical solution of the present application, a stacked solar cell is provided, which includes a bottom cell, a top cell and a tunneling composite layer located between the bottom cell and the top cell, wherein the tunneling composite layer includes a plurality of sub-tunneling layers, and the plurality of sub-tunneling layers have different work functions, so that the tunneling composite layer of the stacked solar cell has different energy levels, so that the plurality of sub-tunneling layers constitute an energy level gradient, and during the movement of electrons and holes, the recombination barrier of carriers between the top cell and the bottom cell is slowed down, the effective recombination of carriers is promoted, and the open circuit voltage, short-circuit current density and photoelectric conversion efficiency of the stacked solar cell are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 is a schematic cross-sectional structure diagram of a stacked solar cell according to an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of the energy band structure of a tunneling composite layer of a stacked solar cell according to an embodiment of the present application;

[0020] Figure 3 is a schematic cross-sectional structure diagram of another stacked solar cell according to an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of the energy band structure of a tunneling composite layer of another tandem solar cell according to an embodiment of the present application;

[0022] Figure 5 is a flow chart of a method for preparing a stacked solar cell according to an embodiment of the present application;

[0023] Figure 6 is a schematic diagram of the process structure of another stacked solar cell according to an embodiment of the present application;

[0024] Figure 7 is a schematic diagram of the process structure of another stacked solar cell according to an embodiment of the present application;

[0025] Figure 8 It is a schematic diagram of the process structure of a stacked solar cell according to the control group of this application.

[0026] The above drawings include the following reference numerals:

[0027] 10. Bottom cell; 101. Bottom TCO film layer; 102. First hydrogenated amorphous silicon layer; 1031. First intrinsic hydrogenated amorphous silicon layer; 1032. Second intrinsic hydrogenated amorphous silicon layer; 104. Single crystal silicon layer; 105. Second hydrogenated amorphous silicon layer; 106. First electrode; 20. Tunneling composite layer; 200. Single-layer tunneling composite layer; 201. First sub-tunneling layer; 202. Second sub-tunneling layer; 203. Third sub-tunneling layer; 30. Top cell; 301. Hole transport layer; 302. Perovskite absorption layer; 303. Electron transport layer; 304. Buffer layer; 305. Transparent electrode layer; 306. Second electrode. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0030] 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 sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. 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 comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] As described in the background technology, the industry currently generally uses magnetron sputtering to prepare a single-layer TCO structure as a tunneling composite layer. The recombination barrier of carriers between the top cell and the bottom cell in the single layer is high, which is not conducive to the effective recombination between carriers, resulting in low open circuit voltage, short circuit current density and photoelectric conversion efficiency of the stacked solar cell. In order to solve the above technical problems, the present application provides a stacked solar cell and a preparation method thereof.

[0032] According to one aspect of the present application, a stacked solar cell is provided, such as Figure 1As shown, the solar cell includes a bottom cell 10, a top cell 30 and a tunneling composite layer 20 located between the bottom cell 10 and the top cell 30, wherein the tunneling composite layer 20 includes a plurality of sub-tunneling layers, each of which has a different work function, so that the tunneling composite layer of the stacked solar cell has different energy levels, so that the plurality of sub-tunneling layers form an energy level gradient, and during the movement of electrons and holes, the recombination barrier of carriers between the top cell and the bottom cell is slowed down, the effective recombination of carriers is promoted, and the open circuit voltage, short circuit current density and photoelectric conversion efficiency of the stacked solar cell are effectively improved.

[0033] In an optional embodiment, the work function of the tunneling layer in contact with the bottom battery among the multiple sub-tunneling layers is the first work function, and the work functions of the remaining sub-tunneling layers are all greater than the first work function and increase in a direction perpendicular to the bottom battery. Figure 1 As shown, the tunneling composite layer 20 includes a first sub-tunneling layer 201 and a second sub-tunneling layer 202. The work function of the first sub-tunneling layer 201 is a first work function, and the second sub-tunneling layer 202 has a second work function. The first work function is smaller than the second work function, so that the double-layer TCO tunneling composite layer 20 forms an energy level gradient. During the movement of electrons and holes, the recombination barrier of carriers between the top cell and the bottom cell is slowed down, and the effective recombination of carriers is promoted, which effectively improves the open circuit voltage, short circuit current density and photoelectric conversion efficiency of the stacked solar cell.

[0034] Specifically, the energy band structure diagram of the double-layer tunneling composite layer 20 is as follows: Figure 2 As shown, when the stacked solar cell is irradiated by a light source, due to the energy level gradient formed in the tunneling recombination layer 20, electrons jump from the bottom cell 10 to the first sub-tunneling layer 201, and jump from the first sub-tunneling layer 201 to the second sub-tunneling layer 202, and holes jump from the top cell 30 to the second sub-tunneling layer 202 to recombine with the electrons, wherein the first work function of the first sub-tunneling layer 201 is less than the second work function of the second sub-tunneling layer 202, which reduces the recombination barrier of carriers between the top cell 30 and the bottom cell 10, promotes the effective recombination of carriers, and effectively improves the open circuit voltage, short-circuit current density and photoelectric conversion efficiency of the stacked solar cell.

[0035] In another optional embodiment, Figure 3 As shown, the tunneling composite layer 20 further includes a third tunneling sub-layer 203, and the work function of the third tunneling sub-layer 203 is a third work function, wherein the third work function is greater than the second work function and greater than the first work function, and in addition, Figure 3 The other structural positions shown in Figure 1 The structural position relationship is the same as in , and will not be repeated here.

[0036] Specifically, the energy band structure diagram of the three-layer tunneling composite layer 20 is as follows: Figure 4 As shown, when the stacked solar cell is irradiated by a light source, due to the energy level gradient formed in the tunneling recombination layer 20, electrons jump from the bottom cell 10 to the first sub-tunneling layer 201, and jump from the first sub-tunneling layer 201 to the second sub-tunneling layer 202 and the third sub-tunneling layer 203, and holes jump from the top cell 30 to the third sub-tunneling layer 203 to recombine with electrons, wherein the third work function>the second work function>the first work function, which reduces the recombination barrier of carriers between the top cell 30 and the bottom cell 10, promotes the effective recombination of carriers, and effectively improves the open circuit voltage, short circuit current density and photoelectric conversion efficiency of the perovskite / crystalline silicon two-terminal stacked solar cell.

[0037] In some optional embodiments, the material of each sub-tunneling layer includes a transparent conductive oxide.

[0038] Specifically, transparent conductive oxide (TCO) has high transmittance and low resistivity in the visible light spectrum range (380nm ~ 780nm). Using transparent conductive oxide as the material of the tunneling layer can form a high energy barrier between electrons and holes. When the battery is illuminated by sunlight, a compound effect is formed, and electrons and holes jump upward, so that the charge inside the battery can be quickly transferred, thereby improving the efficiency of the solar cell. In addition, the chemical properties of transparent conductive oxide are relatively stable, which can prevent short circuits and leakage inside the battery and extend the life of the solar cell.

[0039] In some optional embodiments, the transparent conductive oxide material includes one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO). Those skilled in the art can make reasonable selections according to actual needs, and this application does not make specific limitations.

[0040] In an optional embodiment, when the transparent conductive oxide materials of the sub-tunneling layers are different, and the first sub-tunneling layer 201 of the tunneling composite layer 20 is an IZO layer and the second sub-tunneling layer 202 is an ITO layer, the conversion efficiency of the stacked solar cell is better than when the first sub-tunneling layer 201 of the tunneling composite layer 20 is an ITO layer and the second sub-tunneling layer 202 is an ITO layer.

[0041] In some optional embodiments, the thickness of each sub-tunneling layer is 5nm to 80nm to ensure that the thickness of the tunneling layer does not affect the recombination barrier of carriers between the top battery and the bottom battery, thereby increasing the process window while ensuring the conversion efficiency of the battery.

[0042] According to another aspect of the present application, a method for manufacturing a stacked solar cell is also provided, such as Figure 5As shown, the method comprises the following steps:

[0043] S101: providing a bottom battery;

[0044] S102: forming a tunneling composite layer on the front side of the bottom battery; wherein the tunneling composite layer includes a plurality of sub-tunneling layers, and the plurality of sub-tunneling layers have different work functions;

[0045] S103: forming a top battery on a surface of the tunneling composite layer facing away from the bottom battery.

[0046] By adopting the above-mentioned preparation method of the embodiment of the present application, a multilayer sub-tunneling layer of the tunneling composite layer is formed between the bottom battery and the top battery through multiple deposition processes, wherein the first layer of sub-tunneling can act as a buffer layer, which is beneficial to reduce the sputtering damage to the crystalline silicon bottom battery in the subsequent tunneling composite layer preparation process, and adjust the gas pressure and reaction gas concentration during the deposition process so that each layer of the sub-tunneling layer has a different work function, so that the multilayer sub-tunneling layer constitutes an energy level gradient, which slows down the recombination barrier of carriers between the top battery and the bottom battery, promotes the effective recombination of carriers, and effectively improves the open circuit voltage, short-circuit current density and photoelectric conversion efficiency of the perovskite / crystalline silicon two-terminal stacked solar cell.

[0047] The exemplary embodiments of the method for preparing a stacked solar cell provided by the present application will be described in more detail below in conjunction with the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concepts of these exemplary embodiments to ordinary technicians in the field.

[0048] First, proceed to step S101: Figures 6 to 8 As shown, a bottom cell 10 is provided.

[0049] Specifically, the bottom cell 10 may include a silicon bottom cell, such as Figure 6 (a) to Figure 8 As shown in (a), on the first surface of the underlying TCO film layer 101, a first hydrogenated amorphous silicon layer 102, a first intrinsic hydrogenated amorphous silicon layer 1031, a single crystal silicon layer 104, a second intrinsic hydrogenated amorphous silicon layer 1032, and a second hydrogenated amorphous silicon layer 105 are stacked in sequence along a direction perpendicular to the first surface. The surface of the second hydrogenated amorphous silicon layer 105 facing away from the underlying TCO film layer 101 is the front side of the bottom battery 10, and a first electrode 106 is formed on the back side of the underlying TCO film layer 101.

[0050] Then, on the provided bottom battery 10, step S102 is performed: Figure 6 (b) to Figure 8As shown in (b), a tunneling composite layer 20 is formed on the front side of the bottom cell.

[0051] Specifically, a plurality of sub-tunneling layers are formed on the front side of the bottom battery by using a multiple deposition process. In the deposition process, a gas containing argon and oxygen is used as a raw material gas, the flow rate of the argon gas is 30 sccm to 400 sccm, the flow rate of the oxygen is 0.1 sccm to 20 sccm, the reaction pressure is 0.1 Pa to 1 Pa, the reaction temperature is 25° C. to 230° C., and the vacuum degree at the start reaction time of each deposition process is less than 1×10 -4 Pa.

[0052] In the above-mentioned multiple deposition processes, the concentration of the reaction gas, ie, the flow rate of argon gas and oxygen gas and the reaction pressure are adjusted so that each sub-tunneling layer has a different work function.

[0053] Specifically, the deposition process includes but is not limited to physical vapor deposition (PVD), chemical vapor deposition (CVD) and atomic layer deposition (ALD), among which physical vapor deposition (PVD) includes but is not limited to magnetron sputtering process, reactive sputtering process, DC sputtering process, AC sputtering process, vacuum coating process, arc evaporation process, chemical vapor deposition (CVD) includes but is not limited to plasma enhanced chemical vapor deposition (PECVD), metal organic compound chemical vapor deposition (MOCVD), laser induced chemical vapor deposition (LCVD), and technicians in this field can make reasonable selections according to actual needs, and no specific limitation is made without application.

[0054] In some optional embodiments, the tunneling composite layer 20 is prepared by a magnetron sputtering process. During the sputtering process of the tunneling composite layer 20, ions and atoms on the surface of the target material are caused to leave the target material, and a sub-tunneling film layer is formed on the bottom battery 10 and the sub-tunneling layer. In addition, the DC power applied to the target material is different when preparing different sub-tunneling layers. When preparing the first sub-tunneling layer 201 of the tunneling composite layer, the DC power applied to the target material is controlled between 10W and 100W. When preparing other sub-tunneling layers, the DC power applied to the target material is controlled between 10W and 500W, so that each sub-tunneling layer of the tunneling composite layer 20 has a different work function.

[0055] Then, on the formed tunneling composite layer 20, step S103 is performed: Figure 6 (c) to Figure 8 As shown in (c), a top cell 30 is formed on the surface of the tunneling composite layer 20 facing away from the bottom cell 10.

[0056] Specifically, the above step S103 may include the following steps:

[0057] S1031: forming a hole transport layer 301 on the tunneling composite layer 20 by a deposition process, wherein the material of the hole transport layer 301 may include but is not limited to a combination of one or more materials selected from the group consisting of NiO, MoO3, Cu2O, CuI, CuPc, CuSCN, redox graphene, PTAA, Spiro-OMeTAD, PEDOT:PSS, Ploy-TPD, and polyvinyl carbazole (PVK);

[0058] S1032: forming a perovskite absorption layer 302 on the hole transport layer 301, wherein the process of forming the perovskite absorption layer 302 includes but is not limited to spraying, spin coating, thermal evaporation or screen printing followed by low temperature (<150° C.) heat treatment;

[0059] S1033: Forming an electron transport layer 303 on the perovskite absorption layer 302 by a deposition process, wherein the material of the electron transport layer 303 may include but is not limited to SnO2, ZnO, TiO2, PCBM and C 60 A combination of one or more materials;

[0060] S1034: forming a buffer layer 304 on the electron transport layer 303 by a deposition process. The material of the buffer layer 304 may include but is not limited to SnO2, TiO2, C 60 , a combination of one or more materials selected from PCBB-2CN-2C8;

[0061] S1035: forming a transparent electrode layer 305 on the buffer layer 304 by a deposition process, wherein the material of the transparent electrode layer 305 may include but is not limited to a combination of one or more materials selected from the group consisting of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO);

[0062] S1036: forming a second electrode 306 on the transparent electrode layer 305. The process of forming the second electrode 306 includes but is not limited to screen printing, thermal evaporation and magnetron sputtering processes. The electrode material includes but is not limited to a combination of one or more materials of Au, Ag, Cu and Al.

[0063] The following will further illustrate how to form a stacked solar cell using the method for preparing a trench stacked solar cell of the present application in conjunction with an embodiment.

[0064] Example 1

[0065] The method for preparing the IZO / ITO double-layer tunneling composite layer provided in this embodiment includes the following steps: Figure 6 As shown:

[0066] A silicon bottom battery 10 is provided. A boron diffusion layer is formed on an N-type silicon wafer by a laser grooving and local diffusion process, and the borosilicate glass is removed and the silicon wafer is cleaned to form a single crystal silicon layer 104. A first intrinsic hydrogenated amorphous silicon layer 1031 and a second intrinsic hydrogenated amorphous silicon layer 1032 are respectively formed on two opposite surfaces of the single crystal silicon layer 104 by a plasma vapor deposition process. A P-type first hydrogenated amorphous silicon layer 102 is formed on the surface of the first intrinsic hydrogenated amorphous silicon layer 1031, and an N-type second hydrogenated amorphous silicon layer 105 is formed on the surface of the second intrinsic hydrogenated amorphous silicon layer 1032 by a plasma vapor deposition process. A bottom TCO film layer 101 is formed on the surface of the first hydrogenated amorphous silicon layer 102 away from the single crystal silicon layer 104 by a magnetron sputtering process. A first electrode 106 is formed on the surface of the bottom TCO film layer 101 away from the single crystal silicon layer 104 by screen printing and high temperature sintering, so as to prepare a silicon bottom battery 10, such as Figure 6 (a) shown.

[0067] The first tunneling sub-layer 201 is prepared by a magnetron sputtering process. Specifically, the silicon bottom cell 10 is placed in a reaction chamber of a magnetron sputtering apparatus, and the reaction chamber of the magnetron sputtering apparatus is evacuated. When the vacuum degree in the chamber is less than 1×10 -4 After the pressure of the reaction chamber reaches 0.37 Pa, argon gas is introduced into the reaction chamber with a flow rate of 120 sccm, the reaction chamber pressure is maintained at 0.37 Pa, and the temperature in the reaction chamber is at room temperature. Then, 1.4 sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stabilized, a DC power supply is connected to apply a DC power of 20 W to the IZO target, and a single-layer IZO film with a thickness of 20 nm is deposited on the surface of the silicon bottom battery 10 as the first sub-tunneling layer 201, as shown in FIG. Figure 6 (b)

[0068] After the first tunneling sub-layer 201 is prepared, the second tunneling sub-layer 202 is prepared by the magnetron sputtering process. The reaction chamber of the magnetron sputtering device is heated to 200° C. and the reaction chamber of the magnetron sputtering device is evacuated. When the vacuum degree is less than 1×10 -4 After the reaction chamber reaches 0.28 Pa, argon gas is introduced into the reaction chamber with a flow rate of 90 sccm to maintain the reaction chamber pressure at 0.28 Pa. Then, 2.1 sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stabilized, a DC power supply is connected to apply a DC power of 100 W to the ITO target material to deposit a 60 nm thick ITO film layer on the surface of the first sub-tunneling layer 201 as the second sub-tunneling layer 202 to form an IZO / ITO double-layer tunneling composite layer 20, as shown in FIG. Figure 6 (b)

[0069] A nickel oxide layer with a thickness of 180 nm is formed on the second tunneling sub-layer 202 by a deposition process to serve as the hole transport layer 301. Figure 6 (c)

[0070] The perovskite absorption layer 302 is formed on the hole transport layer 301 by spin coating process, and the thickness is 400 nm. Figure 6 (c)

[0071] A deposition process is used to form a C on the perovskite absorption layer 302 60 A layer having a thickness of 180 nm is used as an electron transport layer 303, such as Figure 6 (c)

[0072] A SnO2 layer with a thickness of 50 nm is formed on the electron transport layer 303 by a deposition process to serve as a buffer layer 304. Figure 6 (c)

[0073] An indium zinc oxide layer with a thickness of 40 nm is formed on the buffer layer 304 by a deposition process to form a transparent electrode layer 305. Figure 6 (c)

[0074] A second electrode is formed on the transparent electrode layer 305 by magnetron sputtering process, with a thickness of 40 nm and a material of Ag. Figure 6 (c) as shown.

[0075] Example 2

[0076] The method for preparing the ITO / ITO double-layer tunneling composite layer provided in this embodiment comprises the following steps: Figure 6 As shown:

[0077] Provide a silicon bottom cell 10, such as Figure 6 (a), wherein the silicon bottom cell 10 is the same as that in Example 1;

[0078] The first tunneling sub-layer 201 is prepared by a magnetron sputtering process. Specifically, the silicon bottom battery 10 is placed in a reaction chamber of a magnetron sputtering instrument, and the reaction chamber of the magnetron sputtering instrument is evacuated and heated to 200° C. When the vacuum degree in the chamber is lower than 1×10-4Pa, argon gas is introduced into the reaction chamber with an argon gas flow rate of 105sccm to maintain the reaction chamber pressure at 0.33Pa. Then, 1.6sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stable, a DC power supply is connected, and a DC power of 20W is applied to the ITO target to deposit a 20nm thick ITO film on the surface of the silicon bottom battery 10 as the first tunneling sub-layer 201. Figure 6 (b)

[0079] After the first tunneling sub-layer 201 is prepared, the temperature of the reaction chamber is kept constant, and the reaction chamber of the magnetron sputtering apparatus is evacuated. When the vacuum degree of the reaction chamber is evacuated to less than 1×10 -4After the reaction chamber reaches 0.28 Pa, argon gas is introduced into the reaction chamber with a flow rate of 90 sccm to maintain the reaction chamber pressure at 0.28 Pa. Then, 2.1 sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stabilized, a DC power supply is connected to apply a DC power of 100 W to the ITO target material to deposit a 60 nm thick ITO film layer on the surface of the first sub-tunneling layer 201 as the second sub-tunneling layer 202 to form an ITO / ITO double-layer tunneling composite layer 20, such as Figure 6 (b)

[0080] A nickel oxide layer with a thickness of 180 nm is formed on the second tunneling sub-layer 202 by a deposition process to serve as the hole transport layer 301. Figure 6 (c)

[0081] The perovskite absorption layer 302 is formed on the hole transport layer 301 by spin coating process, and the thickness is 400 nm. Figure 6 (c)

[0082] A deposition process is used to form a C on the perovskite absorption layer 302 60 A layer having a thickness of 180 nm is used as an electron transport layer 303, such as Figure 6 (c)

[0083] A SnO2 layer with a thickness of 50 nm is formed on the electron transport layer 303 by a deposition process to serve as a buffer layer 304. Figure 6 (c)

[0084] An indium zinc oxide layer with a thickness of 40 nm is formed on the buffer layer 304 by a deposition process to form a transparent electrode layer 305. Figure 6 (c)

[0085] A second electrode is formed on the transparent electrode layer 305 by magnetron sputtering process, with a thickness of 40 nm and a material of Ag. Figure 6 (c) as shown.

[0086] Example 3

[0087] The method for preparing the IZrO / ITO double-layer tunneling composite layer provided in this embodiment comprises the following steps: Figure 6 As shown:

[0088] Provide a silicon bottom cell 10, such as Figure 6 (a), wherein the silicon bottom cell 10 is the same as that in Example 1;

[0089] The first tunneling sub-layer 201 is prepared by a magnetron sputtering process. Specifically, the silicon bottom cell 10 is placed in a reaction chamber of a magnetron sputtering apparatus, and the reaction chamber of the magnetron sputtering apparatus is evacuated. When the vacuum degree in the chamber is less than 1×10-4 After the pressure of the reaction chamber reaches 0.19 Pa, argon gas is introduced into the reaction chamber with a flow rate of 60 sccm, the pressure of the reaction chamber is maintained at 0.19 Pa, and the temperature in the reaction chamber is at room temperature. Then, 3.1 sccm of O2 is introduced into the reaction chamber. After the pressure of the chamber is stabilized, a DC power supply is connected to apply a DC power of 20 W to the IZrO target, and a single-layer IZrO film with a thickness of 20 nm is deposited on the surface of the silicon bottom battery 10 as the first sub-tunneling layer 201, as shown in FIG. Figure 6 (b)

[0090] After the first tunneling sub-layer 201 is prepared, the reaction chamber of the magnetron sputtering apparatus is heated to 200° C. and the reaction chamber of the magnetron sputtering apparatus is evacuated to a vacuum level of less than 1×10 -4 After the reaction chamber reaches 0.28 Pa, argon gas is introduced into the reaction chamber with a flow rate of 90 sccm to maintain the reaction chamber pressure at 0.28 Pa. Then, 2.1 sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stabilized, a DC power supply is connected to apply a DC power of 100 W to the ITO target material to deposit a 60 nm thick ITO film layer on the surface of the first sub-tunneling layer 201 as the second sub-tunneling layer 202 to form an IZrO / ITO double-layer tunneling composite layer 20, such as Figure 6 (b)

[0091] A nickel oxide layer with a thickness of 180 nm is formed on the second tunneling sub-layer 202 by a deposition process to serve as the hole transport layer 301. Figure 6 (c)

[0092] The perovskite absorption layer 302 is formed on the hole transport layer 301 by spin coating process, and the thickness is 400 nm. Figure 6 (c)

[0093] A deposition process is used to form a C on the perovskite absorption layer 302 60 A layer having a thickness of 180 nm is used as an electron transport layer 303, such as Figure 6 (c)

[0094] A SnO2 layer with a thickness of 50 nm is formed on the electron transport layer 303 by a deposition process to serve as a buffer layer 304. Figure 6 (c)

[0095] An indium zinc oxide layer with a thickness of 40 nm is formed on the buffer layer 304 by a deposition process to form a transparent electrode layer 305. Figure 6 (c)

[0096] A second electrode is formed on the transparent electrode layer 305 by magnetron sputtering process, with a thickness of 40 nm and a material of Ag. Figure 6 (c) as shown.

[0097] Example 4

[0098] The method for preparing the IZO / IZO / ITO three-layer tunneling composite layer provided in this embodiment includes the following steps: Figure 7 As shown:

[0099] Provide a silicon bottom cell 10, such as Figure 7 (a), wherein the silicon bottom cell 10 is the same as that in Example 1;

[0100] The first tunneling sub-layer 201 is prepared by a magnetron sputtering process. Specifically, the silicon bottom cell 10 is placed in a reaction chamber of a magnetron sputtering apparatus, and the reaction chamber of the magnetron sputtering apparatus is evacuated. When the vacuum degree in the chamber is less than 1×10 -4 After the pressure of the reaction chamber reaches 0.37 Pa, argon gas is introduced into the reaction chamber with a flow rate of 120 sccm, the pressure of the reaction chamber is maintained at 0.37 Pa, and the temperature in the reaction chamber is at room temperature. Then, 1.4 sccm of O2 is introduced into the reaction chamber. After the pressure of the chamber is stabilized, a DC power supply is connected to apply a DC power of 20 W to the IZO target, and a single-layer IZO film with a thickness of 5 nm is deposited on the surface of the silicon bottom battery 10 as the first sub-tunneling layer 201, as shown in FIG. Figure 7 (b)

[0101] After the first tunneling layer 201 is prepared, the vacuum degree is ensured to be less than 1×10 -4 Pa, argon gas is introduced into the reaction chamber, the argon gas flow rate is 75sccm, the reaction chamber pressure is maintained at 0.23Pa, the temperature in the reaction chamber is at room temperature, and then 2.6sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stable, a DC power supply is connected, and a DC power of 20W is applied to the IZO target, and a layer of IZO film with a thickness of 15nm is deposited on the surface of the first sub-tunneling layer 201 as the second sub-tunneling layer 202, such as Figure 7 (b)

[0102] After the second tunneling sub-layer 202 is prepared, the reaction chamber is heated to 200° C. to ensure that the vacuum degree is less than 1×10 - 4 Under the condition of 1.5 Pa, argon gas is introduced into the reaction chamber with a flow rate of 90 sccm to maintain the pressure of the reaction chamber at 0.28 Pa. Then, 2.1 sccm of O2 is introduced into the reaction chamber. After the chamber pressure is stable, a DC power supply is connected to apply a DC power of 100 W to the ITO target material, and a layer of ITO film with a thickness of 60 nm is continuously deposited on the surface of the second sub-tunneling layer 202 as the third sub-tunneling layer 203 to form an IZO / IZO / ITO three-layer tunneling composite layer 20, such as Figure 7 (b)

[0103] A nickel oxide layer with a thickness of 180 nm is formed on the third tunneling sub-layer 203 by a deposition process to serve as the hole transport layer 301. Figure 7 (c)

[0104] The perovskite absorption layer 302 is formed on the hole transport layer 301 by spin coating process, and the thickness is 400 nm. Figure 7 (c)

[0105] A deposition process is used to form a C on the perovskite absorption layer 302 60 A layer having a thickness of 180 nm is used as an electron transport layer 303, such as Figure 7 (c)

[0106] A SnO2 layer with a thickness of 50 nm is formed on the electron transport layer 303 by a deposition process to serve as a buffer layer 304. Figure 7 (c)

[0107] An indium zinc oxide layer with a thickness of 40 nm is formed on the buffer layer 304 by a deposition process to form a transparent electrode layer 305. Figure 7 (c)

[0108] A second electrode is formed on the transparent electrode layer 305 by magnetron sputtering process, with a thickness of 40 nm and a material of Ag. Figure 7 (c) as shown.

[0109] Comparative Example 1

[0110] The preparation method of the ITO single-layer tunneling composite layer provided in this comparative example comprises the following steps: Figure 8 As shown:

[0111] Provide a silicon bottom cell 10, such as Figure 8 (a), wherein the silicon bottom cell 10 is the same as that in Example 1;

[0112] The ITO single-layer tunneling composite layer 200 is formed by magnetron sputtering. Specifically, the silicon bottom cell 10 is placed in a reaction chamber of a magnetron sputtering apparatus, and the reaction chamber of the magnetron sputtering apparatus is evacuated. The chamber is heated to 200° C. and the vacuum degree is less than 1×10 -4 After the pressure of the reaction chamber reaches 0.28 Pa, argon gas is introduced into the reaction chamber with a flow rate of 90 sccm to maintain the pressure of the reaction chamber at 0.28 Pa. Then, 2.1 sccm of O2 is introduced into the reaction chamber. After the pressure of the chamber is stabilized, a DC power supply is connected to apply a DC power of 100 W to the ITO target material to deposit a single-layer ITO film with a thickness of 80 nm on the surface of the silicon bottom battery 10 as a single-layer tunneling composite layer 200. Figure 8 (b)

[0113] A nickel oxide layer with a thickness of 180 nm is formed on the single-layer tunneling composite layer 200 by a deposition process to serve as the hole transport layer 301. Figure 8 (c)

[0114] The perovskite absorption layer 302 is formed on the hole transport layer 301 by spin coating process, and the thickness is 400 nm. Figure 8 (c)

[0115] A deposition process is used to form a C on the perovskite absorption layer 302 60 A layer having a thickness of 180 nm is used as an electron transport layer 303, such as Figure 8 (c)

[0116] A SnO2 layer with a thickness of 50 nm is formed on the electron transport layer 303 by a deposition process to serve as a buffer layer 304. Figure 8 (c)

[0117] An indium zinc oxide layer with a thickness of 40 nm is formed on the buffer layer 304 by a deposition process to form a transparent electrode layer 305. Figure 8 (c)

[0118] A second electrode is formed on the transparent electrode layer 305 by magnetron sputtering process, with a thickness of 40 nm and a material of Ag. Figure 8 (c) as shown.

[0119] The spectrum distribution is AM1.5G and the light intensity is 100mw / cm 2 The Oriel 300W solar simulator was used as the light source to test the photoelectric performance of the laminated solar cells obtained in the above Examples 1 to 4 and Comparative Example 1. The JV curve was measured by a Keithly 2400 digital source meter, and the photoelectric performance test parameters were obtained, as shown in Table 1:

[0120] Table 1

[0121]

[0122] It can be seen from the results in Table 1 that, compared with Comparative Example 1, the open circuit voltage Voc, short circuit current density Jsc, fill factor FF and conversion efficiency PCE of the stacked solar cells based on the multi-layer tunneling composite layer of Examples 1 to 4 are significantly improved, among which the conversion efficiency of the stacked solar cell composed of the IZO / ITO double-layer tunneling composite layer in Example 1 is the most obvious.

[0123] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0124] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A stacked solar cell, characterized in that: include: A bottom battery, a top battery and a tunneling composite layer located between the bottom battery and the top battery, wherein the tunneling composite layer includes a plurality of sub-tunneling layers, and the plurality of sub-tunneling layers have different work functions.

2. The tandem solar cell according to claim 1, characterized in that: The work function of the sub-tunneling layer in contact with the bottom battery is a first work function, and the work functions of the remaining sub-tunneling layers are all greater than the first work function and increase along a direction perpendicular to the bottom battery.

3. The tandem solar cell according to claim 1, characterized in that: The material of each of the sub-tunneling layers includes transparent conductive oxide.

4. The stacked solar cell according to claim 3, characterized in that: The transparent conductive oxide material includes one or more of indium zinc oxide IZO, indium tin oxide ITO, indium hydroxide-doped In2O3:H, aluminum-doped zinc oxide AZO, zirconium-doped indium oxide IZrO and zinc-doped tin oxide ZTO.

5. The tandem solar cell according to claim 4, characterized in that: The transparent conductive oxide materials of each sub-tunneling layer are different.

6. The tandem solar cell according to any one of claims 1 to 5, characterized in that: The thickness of each sub-tunneling layer is 5nm-80nm.

7. A method for preparing a tandem solar cell according to any one of claims 1 to 6, characterized in that: include: Provide bottom battery; Forming a tunneling composite layer on the front side of the bottom battery; wherein the tunneling composite layer includes multiple sub-tunneling layers, and the multiple sub-tunneling layers have different work functions; A top cell is formed on a surface of the tunneling recombination layer facing away from the bottom cell.

8. The method for preparing a stacked solar cell according to claim 7, characterized in that: The steps of forming the tunneling composite layer include: A plurality of sub-tunneling layers are formed on the front side of the bottom battery by multiple deposition processes. In the deposition process, a gas containing argon and oxygen is used as a raw material gas. The flow rate of the argon is 30 sccm to 400 sccm, the flow rate of the oxygen is 0.1 sccm to 20 sccm, the reaction pressure is 0.1 Pa to 1 Pa, and the reaction temperature is 25°C to 230°C.

9. The method for preparing a stacked solar cell according to claim 8, characterized in that: A different flow rate of the argon gas and a different flow rate of the oxygen gas are used in each deposition process, and a different reaction pressure is used in each deposition process.

10. The method for preparing a stacked solar cell according to claim 8 or 9, characterized in that: The vacuum degree at the start of each deposition process is less than 1×10 -4 Pa, the DC power applied to the target during the deposition process is 10W ~ 500W.

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