Preparation method of laminated solar cell and laminated solar cell

Abstract

The invention discloses a preparation method of a laminated solar cell and the laminated solar cell, and belongs to the technical field of photovoltaics. The method comprises the following steps: forming a bottom cell structure; an atomic layer deposition process is adopted, a first tunnel junction is formed on one side of the bottom cell structure, and the first tunnel junction comprises a first type semiconductor thin film, a tunnel composite thin film and a second type semiconductor thin film which are sequentially stacked, one of the first type semiconductor thin film and the second type semiconductor thin film is an electron transport thin film, and the other one is a hole transport thin film; and forming a top cell structure on one side, deviating from the bottom cell structure, of the first tunnel junction. The preparation process can be simplified, the preparation efficiency can be improved, the process cost can be reduced, and the photoelectric stability can be improved.

Description

Technical Field

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

[0002] Adjacent photoactive layers in a stacked solar cell are connected by a tunnel junction, which includes two carrier transport layers and a carrier recombination layer located between the two. The related technology uses different processes to prepare the two carrier transport layers and the carrier recombination layer, which is complex, has low preparation efficiency, and high process cost. In addition, film layers with different material properties are stacked by different process methods, which has poor interface compatibility and affects optoelectronic stability. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a method for preparing a stacked solar cell and a stacked solar cell, which can simplify the preparation process, improve the preparation efficiency, reduce the process cost, and improve the optoelectronic stability.

[0004] In a first aspect, the present application provides a method for preparing a stacked solar cell, comprising:

[0005] forming a bottom battery structure;

[0006] A first tunnel junction is formed on one side of the bottom battery structure by an atomic layer deposition process, wherein the first tunnel junction comprises a first type semiconductor film, a tunnel composite film, and a second type semiconductor film which are sequentially stacked, wherein one of the first type semiconductor film and the second type semiconductor film is an electron transport film, and the other is a hole transport film;

[0007] A top cell structure is formed on a side of the first tunneling junction facing away from the bottom cell structure.

[0008] According to the preparation method of the stacked solar cell of the present application, a first tunnel junction is formed on one side of the bottom cell structure through an atomic layer deposition process, so that the first type semiconductor film, the tunnel composite film and the second type semiconductor film in the first tunnel junction are prepared by one process, which simplifies the preparation process, improves the preparation efficiency, and reduces the process cost. In addition, the thin films in the first tunnel junction are superimposed by the same atomic layer deposition method, which improves the interface compatibility, and improves the uniformity, density and optoelectronic stability of the first tunnel junction.

[0009] According to one embodiment of the present application, the thickness of the first tunnel junction is 20nm-65nm.

[0010] According to one embodiment of the present application, the method for forming each thin film in the first tunnel junction includes:

[0011] Alternately introducing a first precursor and a common reactant to allow the first precursor and the common reactant to react to form a thin film; or,

[0012] First, alternately introduce the second precursor and the common reactant to make the second precursor react with the common reactant, and then alternately introduce the third precursor and the common reactant to make the third precursor react with the common reactant to produce a thin film; or,

[0013] The fourth precursor and the fifth precursor are introduced alternately with the common reactant, so that the fourth precursor and the fifth precursor react with the common reactant at the same time to form a thin film.

[0014] According to one embodiment of the present application, the method further includes:

[0015] An annealing process is performed after forming the first tunnel junction.

[0016] According to one embodiment of the present application, the electron transport film includes at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide and gallium oxide; and / or,

[0017] The hole transport film comprises at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide and antimony oxide; and / or,

[0018] The tunneling composite film includes at least one of tin-doped indium oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and gallium-doped zinc oxide.

[0019] According to one embodiment of the present application, before forming a top battery structure on a side of the first tunnel junction away from the bottom battery structure, the method further includes:

[0020] forming an intermediate cell structure on a side of the first tunnel junction away from the bottom cell structure;

[0021] An atomic layer deposition process is used to form a second tunnel junction on the side of the middle battery structure away from the first tunnel junction, and the structure of the second tunnel junction is the same as that of the first tunnel junction; the top battery structure is located on the side of the second tunnel junction away from the middle battery structure.

[0022] In a second aspect, the present application provides a stacked solar cell, comprising:

[0023] Bottom battery structure;

[0024] A first tunnel junction is located on one side of the bottom cell structure;

[0025] A top cell structure, located on a side of the first tunnel junction away from the bottom cell structure;

[0026] Among them, the first tunnel junction is an atomic layer structure, and the first tunnel junction includes a first type semiconductor film, a tunneling composite film and a second type semiconductor film which are sequentially stacked between the bottom battery structure and the top battery structure, and one of the first type semiconductor film and the second type semiconductor film is an electron transport film, and the other is a hole transport film.

[0027] According to one embodiment of the present application, the thickness of the first tunnel junction is 20nm-65nm.

[0028] According to one embodiment of the present application, the electron transport film includes at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide and gallium oxide; and / or,

[0029] The hole transport film comprises at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide and antimony oxide; and / or,

[0030] The tunneling composite film includes at least one of tin-doped indium oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and gallium-doped zinc oxide.

[0031] According to one embodiment of the present application, the bottom battery structure includes a bottom electrode, a first carrier transport layer and a first photoactive layer stacked in sequence, and the top battery structure includes a second photoactive layer, a fourth carrier transport layer and a top electrode stacked in sequence;

[0032] The first photoactive layer is disposed close to the first type semiconductor film in the first tunnel junction, and the second photoactive layer is disposed close to the second type semiconductor film in the first tunnel junction; the band gap of the second photoactive layer is greater than the band gap of the first photoactive layer.

[0033] According to one embodiment of the present application, the stacked solar cell further includes an intermediate cell structure and a second tunneling junction alternately arranged between the first tunneling junction and the top cell structure;

[0034] The second tunneling junction is an atomic layer structure, and the structure of the second tunneling junction is the same as that of the first tunneling junction.

[0035] According to one embodiment of the present application, the intermediate cell structure includes a third photoactive layer, and a band gap of the third photoactive layer is larger than a band gap of the first photoactive layer, and smaller than a band gap of the second photoactive layer.

[0036] The above one or more technical solutions in the embodiments of the present application have at least one of the following technical effects:

[0037] Through the atomic layer deposition process, a first tunnel junction is formed on one side of the bottom battery structure, so that the first type semiconductor film, the tunnel composite film and the second type semiconductor film in the first tunnel junction are prepared by one process, which simplifies the preparation process, improves the preparation efficiency and reduces the process cost. In addition, the thin films in the first tunnel junction are superimposed by the same atomic layer deposition method to improve interface compatibility, and improve the uniformity, density and optoelectronic stability of the first tunnel junction.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0040] Figure 1 It is a schematic diagram of a process for preparing a stacked solar cell provided in an embodiment of the present application;

[0041] Figure 2 This is one of the structural schematic diagrams of the stacked solar cell provided in the embodiment of the present application;

[0042] Figure 3 This is the second structural schematic diagram of the stacked solar cell provided in the embodiment of the present application;

[0043] Figure 4 is a schematic structural diagram of a first tunnel junction in a tandem solar cell provided in an embodiment of the present application;

[0044] Figure 5 is a timing diagram of atomic layer deposition in the method for preparing a stacked solar cell provided in an embodiment of the present application;

[0045] Figure 6 It is a schematic diagram of the atomic layer deposition in the method for preparing a stacked solar cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0047] The following describes a method for preparing a stacked solar cell and a stacked solar cell provided in an embodiment of the present application with reference to the accompanying drawings.

[0048] Figure 1A schematic flow chart of a method for preparing a tandem solar cell provided in an embodiment of the present application, wherein the tandem solar cell may be a perovskite tandem solar cell.

[0049] like Figure 1 As shown, the method for preparing a stacked solar cell provided in an embodiment of the present application includes step 110, step 120 and step 130.

[0050] Step 110: forming a bottom battery structure.

[0051] Combination Figure 2 and Figure 3 As shown, the bottom cell structure 1 is located at the bottom of the stacked solar cell.

[0052] In some embodiments, the bottom cell structure 1 may include a bottom electrode 11 , a first carrier transport layer 12 , and a first photoactive layer 13 which are sequentially stacked.

[0053] First, a substrate is provided, and the substrate may include a glass substrate or a flexible substrate. A bottom electrode 11 is formed on one side of the substrate (i.e., the front side of the substrate) by a thin film deposition process. The thin film deposition process includes physical vapor deposition, chemical vapor deposition, atomic layer deposition, laser assisted deposition, etc. The bottom electrode 11 may include one or more of a transparent conductive oxide, a conductive polymer, and a metal electrode.

[0054] A thin film deposition process is used to form a first carrier transport layer 12 on the side of the bottom electrode 11 facing away from the substrate. The first carrier transport layer 12 may be a hole transport layer or an electron transport layer.

[0055] The hole transport layer is used to transport holes and block electrons. The hole transport layer may include NiO x 、TiO x 、ZnO、SnO x and self-assembled monolayer (SAM) materials. The electron transport layer is used to transport electrons and block holes. The electron transport layer may include TiO x 、ZnO、SnO x and C 60 One or more of the above.

[0056] A first photoactive layer 13 is formed on the side of the first carrier transport layer 12 away from the bottom electrode 11 by a thin film deposition process. The first photoactive layer 13 is used to absorb light to generate electron-hole pairs. The first photoactive layer 13 may be a narrow bandgap active layer, which may include one or more of silicon, III-V semiconductor materials, II-VI semiconductor materials, perovskite, and organic materials.

[0057] Step 120: Using an atomic layer deposition process, a first tunnel junction is formed on one side of the bottom battery structure. The first tunnel junction includes a first-type semiconductor film, a tunnel composite film, and a second-type semiconductor film stacked in sequence. One of the first-type semiconductor film and the second-type semiconductor film is an electron transport film, and the other is a hole transport film.

[0058] Combination Figure 4 As shown, an atomic layer deposition process is used to form a first type semiconductor film 21 on one side of the bottom battery structure 1 (i.e., the side of the first photoactive layer 13 away from the first carrier transport layer 12), a tunneling composite film 22 is formed on the side of the first type semiconductor film 21 away from the bottom battery structure 1, and a second type semiconductor film 23 is formed on the side of the tunneling composite film 22 away from the first type semiconductor film 21, thereby obtaining a first tunneling junction 2.

[0059] The conductivity types of the first type semiconductor film 21 and the second type semiconductor film 23 are opposite. One of the first type semiconductor film 21 and the second type semiconductor film 23 is an N-type semiconductor film, and the other is a P-type semiconductor film. The N-type semiconductor film can be used as an electron transport film, and the P-type semiconductor film can be used as a hole transport film.

[0060] The electron mobility of electron transport films can be as low as 0.01 cm 2 / Vs to 20cm 2 / Vs. The hole mobility of the hole transport film can be between 0.01cm 2 / Vs to 20cm 2 / Vs. The conductivity of the tunneling composite film 22 can be between 10 2 S / cm to 10 5 S / cm, the electron mobility can be located at 1cm 2 / Vs to 40cm 2 / Vs, there is no limited range for hole mobility.

[0061] One of the first type semiconductor film 21 and the first carrier transport layer 12 is used for electron transport, and the other is used for hole transport. For example, the first carrier transport layer 12 is a hole transport layer, the first type semiconductor film 21 is an N-type semiconductor film (i.e., an electron transport film), and the second type semiconductor film 23 is a P-type semiconductor film (i.e., a hole transport film); the first carrier transport layer 12 is an electron transport layer, the first type semiconductor film 21 is a P-type semiconductor film (i.e., a hole transport film), and the second type semiconductor film 23 is an N-type semiconductor film (i.e., an electron transport film).

[0062] The related technology mainly prepares tunnel junctions (including two carrier transport layers and a carrier recombination layer between the two carrier transport layers) by combining two or more processes of vacuum evaporation, atomic layer deposition, magnetron sputtering and solution processing. The preparation process requires multiple transfer steps (one transfer step is required for each film layer), the preparation process is complex, the preparation efficiency is low, and the process cost is high. Moreover, film layers with different material properties are superimposed through different processes, and the interface compatibility is poor, which affects the stability of the battery.

[0063] In this embodiment, the first tunnel junction 2 is prepared by a process, and multiple transfer processes are not required during the preparation process, which simplifies the preparation process, improves the preparation efficiency, and reduces the process cost. Film layers with different material properties are superimposed by a process to improve interface compatibility and improve the stability of the battery. In addition, the first tunnel junction 2 is prepared by an atomic layer deposition process to improve the uniformity, density and optoelectronic stability of the first tunnel junction 2, thereby achieving efficient transmission and recombination of carriers at the interface.

[0064] In some embodiments, the thickness of the first tunnel junction 2 is 20 nm to 65 nm. The thicknesses of the first type semiconductor film 21, the tunnel composite film 22 and the second type semiconductor film 23 in the first tunnel junction 2 are respectively in the nanometer range.

[0065] The tunnel junctions prepared by various processes in the related art are relatively thick (thickness greater than 65nm), resulting in a relatively large series resistance of the entire battery, which limits the fill factor of the battery. In addition, the thicker tunnel junction increases the optical loss of the battery and reduces the performance of the battery. However, the present embodiment prepares the first tunnel junction 2 by atomic layer deposition process, which can accurately control the thickness of the first tunnel junction 2 and reduce the thickness of the first tunnel junction 2 to less than 65nm, and as low as 20nm, thereby reducing the series resistance of the battery, improving the fill factor of the battery, reducing optical losses, and improving the performance of the battery.

[0066] In some embodiments, the electron transport film in the first tunnel junction 2 includes at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide, and gallium oxide. For example, if the first type semiconductor film 21 in the first tunnel junction 2 is an N-type semiconductor film, the first type semiconductor film 21 may include at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide, and gallium oxide.

[0067] In the related art, the electron transport layer in the tunnel junction is generally a fullerene / tin oxide double-layer structure. Fullerene has strong parasitic absorption, which will affect the short-circuit current of the battery. In this embodiment, the electron transport film in the first tunnel junction 2 is prepared by atomic layer deposition process, which can accurately design and control the chemical composition of the film, so that the electron transport film no longer uses fullerene, and the short-circuit current of the battery is improved. The electron transport film can be applied to more types of materials, and the flexibility of the electron transport film material selection is improved. The electron transport film selects the appropriate material, which can optimize the performance of electron transport, thereby improving the performance of the battery.

[0068] In some embodiments, the hole transport film in the first tunnel junction 2 includes at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide and antimony oxide. For example, if the second type semiconductor film 23 in the first tunnel junction 2 is a P-type semiconductor film, the second type semiconductor film 23 includes at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide and antimony oxide.

[0069] In the related art, the hole transport layer in the tunnel junction generally uses nickel oxide. However, in this embodiment, the hole transport film in the first tunnel junction 2 is prepared by the atomic layer deposition process, which can accurately design and control the chemical composition of the film, so that the hole transport film is not limited to nickel oxide, and the flexibility of the hole transport film material selection is improved. The hole transport film selects a suitable material, which can optimize the performance of hole transport, thereby improving the performance of the battery.

[0070] In some embodiments, the tunneling composite thin film 22 in the first tunneling junction 2 includes at least one of tin-doped indium oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, and gallium-doped zinc oxide.

[0071] In the related art, the carrier recombination layer in the tunnel junction generally uses tin-doped indium oxide. However, in this embodiment, the tunnel composite film 22 in the first tunnel junction 2 is prepared by the atomic layer deposition process, and the chemical composition of the film can be accurately designed and controlled, so that the tunnel composite film 22 is not limited to tin-doped indium oxide, and the flexibility of the selection of the tunnel composite film 22 is improved. The tunnel composite film 22 selects a suitable material, which can optimize the performance of the tunnel composite film 22, thereby improving the performance of the battery.

[0072] In the atomic layer deposition process, the bottom battery structure 1 is placed in a reaction chamber, and a precursor and a common reactant are introduced into the reaction chamber to react with the precursor and the common reactant to form a thin film, thereby realizing the preparation of the first tunnel junction 2.

[0073] In some embodiments, the method for forming each thin film in the first tunnel junction includes:

[0074] The first precursor and the common reactant are introduced alternately to make the first precursor and the common reactant react to form a thin film.

[0075] Place the substrate into the reaction chamber and combine Figure 5 As shown, the first precursor a is first introduced into the reaction chamber through a carrier gas, and the first precursor a is adsorbed on the substrate. Then, the carrier gas is introduced to remove the excess first precursor a. Then, the common reactant b is introduced into the reaction chamber, and after the common reactant b and the first precursor a undergo a chemical reaction, the carrier gas is introduced to remove the byproducts, thereby preparing a monomolecular film on the substrate. This process is repeated multiple times to prepare a film of the target thickness.

[0076] The electron transport film and the hole transport film can be obtained by reacting the first precursor a with the common reactant b. The common reactant can include water, hydrogen peroxide, oxygen or ozone. The first precursor a used by the electron transport film and the hole transport film can be different, so that the materials of the electron transport film and the hole transport film can be different.

[0077] For example, in electron transport films including SnO x When the electron transport film includes ZnO, the first precursor a may be diethyl zinc (DEZ) or dimethyl zinc (DMZn); when the electron transport film includes In2O3, the first precursor a may be trimethyl indium (TMI) or triethyl indium (TEI); when the electron transport film includes TiO2, the first precursor a may be tetraisopropoxy titanium (TTIP) or tetraethoxy titanium (TEMAT); when the electron transport film includes Cr2O3, the first precursor a may be triisopropoxy chromium (Cr(OiPr)3) or hexacarbonyl chromium (Cr(CO)6); when the electron transport film includes Ga2O3, the first precursor a may be trimethyl gallium (TMGa) or triethyl gallium (TEGa).

[0078] For example, when the hole transport film includes nickel oxide, the first precursor a can be dimethyl nickel (Ni(Cp)2), hexacarbonyl nickel (Ni(CO)6), nickel diacetylacetonate (Ni(acac)2) or tetracarbonyl nickel phosphorus complex (Ni(CO)4(PR3)); when the hole transport film includes copper oxide, the first precursor a can be copper diacetylacetonate (Cu(acac)2), diisopropoxide copper (Cu(OiPr)2) or dimethylamino copper Cu(dmamp)2); when the hole transport film includes cobalt oxide, the first precursor a can be cobalt diacetylacetonate (Co(acac)2), cobalt (II) chloride ( When the hole transport film includes vanadium oxide, the first precursor a can be vanadium trichloride (VCl3), vanadium pentaacetylacetonate (VO(acac)2) or vanadium oxide (VOCl3); when the hole transport film includes chromium oxide, the first precursor a can be triisopropoxy chromium (Cr(OiPr)3), hexacarbonyl chromium (Cr(CO)6) or chromium chloride (CrCl3); when the hole transport film includes antimony oxide, the first precursor a can be antimony trichloride (SbCl3), antimony triacetylacetonate (Sb(acac)3) or an antimony sulfide precursor (such as Sb2S3).

[0079] For the electron transport film, by controlling the dosage ratio and ventilation time ratio of the first precursor a and the common reactant b, the oxygen defect concentration of the electron transport film can be adjusted, thereby adjusting the electron mobility of the electron transport film, so that the electron mobility of the electron transport film is within 0.01 cm 2 / Vs to 20cm 2 / between Vs.

[0080] For the hole transport film, the oxygen content can be controlled by controlling the dosage ratio and ventilation time ratio of the first precursor a and the common reactant b, thereby adjusting the hole mobility of the hole transport film so that the hole mobility of the hole transport film is within 0.01 cm 2 / Vs to 20cm 2 / between Vs.

[0081] In some embodiments, the method for forming each thin film in the first tunnel junction includes:

[0082] First, the second precursor and the common reactant are introduced alternately to react with each other, and then the third precursor and the common reactant are introduced alternately to react with each other to produce a thin film.

[0083] Place the substrate into the reaction chamber and combine Figure 5 and Figure 6As shown, the second precursor c1 is first introduced into the reaction chamber through a carrier gas, and the second precursor c1 is adsorbed on the substrate. Then, the carrier gas is introduced to remove the excess second precursor c1. Then, the common reactant b is introduced into the reaction chamber, and after the common reactant b and the second precursor c1 undergo a chemical reaction, a carrier gas is introduced to remove the by-products. Then, the third precursor c2 is introduced into the reaction chamber, and the third precursor c2 is adsorbed on the substrate. Then, the carrier gas is introduced to remove the excess third precursor c2. Then, the common reactant b is introduced into the reaction chamber, and after the common reactant b and the third precursor c2 undergo a chemical reaction, a carrier gas is introduced to remove the by-products, thereby preparing a thin film on the substrate. The doped thin film is formed by special treatment methods, such as heating, plasma, etc.

[0084] The electron transport film, the tunneling composite film and the hole transport film can be obtained by reacting the second precursor c1, the third precursor c2 and the common reactant b, respectively. The common reactant may include water, hydrogen peroxide, oxygen or ozone. The second precursor c1 and the third precursor c2 used in the electron transport film, the tunneling composite film and the hole transport film may be different, so that the materials of the electron transport film, the tunneling composite film and the hole transport film may be different.

[0085] For example, when the tunneling composite film 22 includes tin-doped indium oxide, the second precursor c1 (indium source) can be trimethyl indium (In(CH3)3In(CH3)3In(CH3)3) or triethyl indium (In(C2H5)3In(C2H5)3In(C2H5)3), and the third precursor c2 (tin source) can be TDMASn, DMTIP or tin chloride (SnCl4); when the tunneling composite film 22 includes fluorine-doped tin oxide, the second precursor c1 (tin source) can be TDMASn, DMTIP or SnCl4, and the third precursor c2 can be TDMASn, DMTIP or SnCl4. (Fluorine source) can be hydrogen fluoride (HF), trifluoroacetic acid (C2HF3O2) or ammonium fluoride (NH4FNH); when the tunneling composite film 22 includes aluminum-doped zinc oxide, the second precursor c1 (zinc source) can be DEZ or DMZn, and the third precursor c2 (aluminum source) can be trimethylaluminum (Al(CH3)3) or triethylaluminum (Al(C2H5)3); when the tunneling composite film 22 includes gallium-doped zinc oxide, the second precursor c1 (zinc source) can be DEZ or DMZn, and the third precursor c2 (gallium source) can be trimethylgallium (Ga(CH3)3).

[0086] For the electron transport film, by controlling the dosage ratio and ventilation time ratio of the second precursor c1, the third precursor c2 and the common reactant b, the element doping concentration of the electron transport film can be adjusted, thereby adjusting the electron mobility of the electron transport film, so that the electron mobility of the electron transport film is within 0.01cm 2 / Vs to 20cm2 / between Vs.

[0087] For the hole transport film, by controlling the dosage ratio and ventilation time ratio of the second precursor c1, the third precursor c2 and the common reactant b, the element doping concentration of the hole transport film can be controlled, thereby adjusting the hole mobility of the hole transport film, so that the hole mobility of the hole transport film is within 0.01cm 2 / Vs to 20cm 2 / between Vs.

[0088] In some embodiments, the method for forming each thin film in the first tunnel junction includes:

[0089] The fourth precursor and the fifth precursor are introduced alternately with the common reactant, so that the fourth precursor and the fifth precursor react with the common reactant at the same time to form a thin film.

[0090] Place the substrate into the reaction chamber and combine Figure 5 As shown, the fourth precursor d1 and the fifth precursor d2 are introduced into the reaction chamber at the same time, and the fourth precursor d1 and the fifth precursor d2 are adsorbed on the substrate. Then, the carrier gas is introduced to remove the excess fourth precursor d1 and the fifth precursor d2. Then, the common reactant b is introduced into the reaction chamber, and the common reactant b reacts chemically with the fourth precursor d1 and the fifth precursor d2 at the same time, and then the carrier gas is introduced to remove the by-products, thereby preparing a single molecule film on the substrate. This process can be repeated many times to prepare a film of the target thickness.

[0091] The electron transport film, the tunneling composite film and the hole transport film can be obtained by reacting the fourth precursor d1 and the fifth precursor d2 with the common reactant b, respectively. The common reactant may include water, hydrogen peroxide, oxygen or ozone. The fourth precursor d1 and the fifth precursor d2 used in the electron transport film, the tunneling composite film and the hole transport film may be different, so that the materials of the electron transport film, the tunneling composite film and the hole transport film may be different.

[0092] For the electron transport film, by controlling the dosage ratio and ventilation time ratio of the fourth precursor d1, the fifth precursor d2 and the common reactant b, the element doping concentration of the electron transport film can be adjusted, thereby adjusting the electron mobility of the electron transport film, so that the electron mobility of the electron transport film is within 0.01cm 2 / Vs to 20cm 2 / between Vs.

[0093] For the hole transport film, by controlling the dosage ratio and ventilation time ratio of the fourth precursor d1, the fifth precursor d2 and the common reactant b, the element doping concentration of the hole transport film can be controlled, thereby adjusting the hole mobility of the hole transport film, so that the hole mobility of the hole transport film is within 0.01cm 2 / Vs to 20cm 2 / between Vs.

[0094] This embodiment can accurately control the growth of each thin film and the optoelectronic properties of each thin film by adjusting the type and dosage of the precursor.

[0095] In some embodiments, the method for preparing the stacked solar cell further includes:

[0096] An annealing process is performed after forming the first tunnel junction.

[0097] The related art uses multiple processes to prepare tunnel junctions, and each process requires annealing of the device, which causes the photoactive layer and other sensitive film layers to undergo multiple high-temperature thermal cycles, causing damage to the photoactive layer and other sensitive film layers to a certain extent. However, this embodiment uses one process to prepare the first tunnel junction 2, and annealing is performed only after the first tunnel junction 2 is prepared. Annealing is not required during the preparation of the first tunnel junction 2, which reduces the number of thermal cycles and pressure cycles of the photoactive layer and other sensitive film layers, and reduces damage to the photoactive layer and other sensitive film layers.

[0098] Step 130 : forming a top cell structure on a side of the first tunnel junction away from the bottom cell structure.

[0099] Combination Figure 2 As shown, the top cell structure 3 is located on the top of the stacked solar cell.

[0100] In some embodiments, the top cell structure 3 includes a second photoactive layer 31 , a fourth carrier transport layer 32 , and a top electrode 33 which are stacked in sequence, and the second photoactive layer 31 is disposed close to the second type semiconductor film 23 in the first tunnel junction 2 .

[0101] After forming the first tunnel junction 2, a second photoactive layer 31 is formed on the side of the second type semiconductor thin film 23 away from the bottom cell structure 1 by a thin film deposition process. The band gap of the second photoactive layer 31 is greater than the band gap of the first photoactive layer 13. The second photoactive layer 31 may be a wide band gap active layer, and the wide band gap active layer may include a perovskite material. Perovskite materials have the advantages of high absorption coefficient, adjustable band gap, low temperature preparation and high efficiency.

[0102] A fourth carrier transport layer 32 is formed on the side of the second photoactive layer 31 away from the first tunnel junction 2 by a thin film deposition process. The fourth carrier transport layer 32 may be a hole transport layer or an electron transport layer. One of the fourth carrier transport layer 32 and the second type semiconductor film 23 is used for electron transport, and the other is used for hole transport. For example, the second type semiconductor film 23 is a P-type semiconductor film (i.e., a hole transport film), and the fourth carrier transport layer 32 is an electron transport layer; the second type semiconductor film 23 is an N-type semiconductor film (i.e., an electron transport film), and the fourth carrier transport layer 32 is a hole transport layer.

[0103] By using a thin film deposition process, a top electrode 33 is formed on a side of the fourth carrier transport layer 32 away from the second photoactive layer 31. The top electrode 33 may include one or more of a transparent conductive oxide, a conductive polymer, and a metal electrode.

[0104] In some embodiments, before forming a top cell structure on the side of the first tunnel junction facing away from the bottom cell structure in step 130, the method for preparing a tandem solar cell further includes:

[0105] forming an intermediate cell structure on a side of the first tunnel junction facing away from the bottom cell structure;

[0106] By using an atomic layer deposition process, a second tunnel junction is formed on the side of the middle battery structure away from the first tunnel junction, and the structure of the second tunnel junction is the same as that of the first tunnel junction; the top battery structure is located on the side of the second tunnel junction away from the middle battery structure.

[0107] like Figure 3 As shown, a thin film deposition process is used to form an intermediate battery structure 4 on the side of the second type semiconductor thin film 23 away from the bottom battery structure 1. Then, an atomic layer deposition process is used to form a second tunnel junction 5 on the side of the intermediate battery structure 4 away from the first tunnel junction 2. The top battery structure 3 is located on the side of the second tunnel junction 5 away from the intermediate battery structure 4. The thickness of the second tunnel junction 5 is 20nm-65nm.

[0108] The second tunnel junction 5 has the same structure as the first tunnel junction 4 , that is, the second tunnel junction 5 includes a first-type semiconductor thin film, a tunnel composite thin film, and a second-type semiconductor thin film that are sequentially stacked.

[0109] In this embodiment, the second tunnel junction 5 is prepared by a process, and multiple transfer processes are not required during the preparation process, which simplifies the preparation process, improves the preparation efficiency, and reduces the process cost. Film layers with different material properties are superimposed by a process to improve interface compatibility and improve the stability of the battery. In addition, the second tunnel junction 5 is prepared by an atomic layer deposition process to improve the uniformity, density and optoelectronic stability of the second tunnel junction 5, thereby achieving efficient transmission and recombination of carriers at the interface.

[0110] It should be noted that a plurality of intermediate battery structures 4 can be prepared between the bottom battery structure 1 and the top battery structure 3, and a third tunnel junction is provided between adjacent intermediate battery structures 4, and the third tunnel junction has the same structure as the first tunnel junction 2 and the second tunnel junction 5. The third tunnel junction is prepared by an atomic layer deposition process, which simplifies the preparation process, improves the preparation efficiency, reduces the process cost, and improves the uniformity, compactness and optoelectronic stability of the third tunnel junction.

[0111] In some embodiments, the intermediate cell structure 4 includes a third photoactive layer 41 , and the band gap of the third photoactive layer 41 is larger than the band gap of the first photoactive layer 13 and smaller than the band gap of the second photoactive layer 31 .

[0112] The third photoactive layer 41 may be a medium bandgap active layer, which may include a perovskite material. For example, the bandgap range of the first photoactive layer 13 is 0.9 eV to 1.2 eV, the bandgap range of the third photoactive layer 41 is 1.2 eV to 1.60 eV (excluding 1.2 eV), and the bandgap range of the second photoactive layer 31 is 1.60 eV to 3.0 eV (excluding 1.60 eV).

[0113] In the case where there are multiple intermediate cell structures 4 between the bottom cell structure 1 and the top cell structure 3, the band gap of the third photoactive layer in the multiple intermediate cell structures 4 is greater than the band gap of the first photoactive layer 13, and less than the band gap of the second photoactive layer 31. Moreover, in the direction from the bottom cell structure 1 to the top cell structure 2, the band gap of the third photoactive layer in the multiple intermediate cell structures 4 gradually increases.

[0114] This embodiment superimposes battery structures with different band gaps so that they can absorb photons in the solar spectrum in segments, thereby improving the photoelectric conversion efficiency and thus breaking through the theoretical efficiency limit of a single material.

[0115] To summarize, in this embodiment, a first tunnel junction 2 is formed on one side of the bottom battery structure 1 through an atomic layer deposition process, so that the first type semiconductor film 21, the tunnel composite film 22 and the second type semiconductor film 23 in the first tunnel junction 2 are prepared through one process, which simplifies the preparation process, improves the preparation efficiency, and reduces the process cost. In addition, the thin films in the first tunnel junction 2 are superimposed through the same atomic layer deposition method to improve interface compatibility, and improve the uniformity, density and optoelectronic stability of the first tunnel junction 2.

[0116] Correspondingly, an embodiment of the present application further provides a stacked solar cell, which can be prepared by the method for preparing the stacked solar cell in the above embodiment.

[0117] like Figure 2 and Figure 3As shown, the stacked solar cell provided in the embodiment of the present application includes a bottom cell structure 1, a first tunnel junction 2 and a top cell structure 3.

[0118] The bottom cell structure 1 is located at the bottom of the stacked solar cell. The first tunnel junction 2 is located at one side of the bottom cell structure 1, and the top cell structure 3 is located at the side of the first tunnel junction 2 away from the bottom cell structure 1. The top cell structure 3 is located at the top of the stacked solar cell.

[0119] The first tunnel junction 2 is an atomic layer structure, that is, the first tunnel junction 2 is formed by an atomic layer deposition process. Figure 4 As shown, the first tunnel junction 2 includes a first type semiconductor film 21, a tunneling composite film 22 and a second type semiconductor film 23 which are sequentially stacked between the bottom battery structure 1 and the top battery structure 3. One of the first type semiconductor film 21 and the second type semiconductor film 23 is an electron transport film, and the other is a hole transport film.

[0120] The conductivity types of the first type semiconductor film 21 and the second type semiconductor film 23 are opposite. One of the first type semiconductor film 21 and the second type semiconductor film 23 is an N-type semiconductor film, and the other is a P-type semiconductor film. The N-type semiconductor film can be used as an electron transport film, and the P-type semiconductor film can be used as a hole transport film.

[0121] The electron mobility of electron transport films can be as low as 0.01 cm 2 / Vs to 20cm 2 / Vs. The hole mobility of the hole transport film can be between 0.01cm 2 / Vs to 20cm 2 / Vs. The conductivity of the tunneling composite film 22 can be between 10 2 S / cm to 10 5 S / cm, the electron mobility can be located at 1cm 2 / Vs to 40cm 2 / Vs, there is no limited range for hole mobility.

[0122] The first tunnel junction 2 in this embodiment is an atomic layer structure, which improves the uniformity, compactness and optoelectronic stability of the first tunnel junction 2, and realizes efficient transmission and recombination of carriers at the interface. The first type semiconductor film 21, the tunnel composite film 22 and the second type semiconductor film 23 in the first tunnel junction 2 are prepared by one process, which simplifies the preparation process, improves the preparation efficiency and reduces the process cost.

[0123] In some embodiments, the thickness of the first tunnel junction 2 is 20 nm to 65 nm. The thicknesses of the first type semiconductor film 21, the tunnel composite film 22 and the second type semiconductor film 23 in the first tunnel junction 2 are respectively in the nanometer range.

[0124] In this embodiment, the thickness of the first tunnel junction 2 is reduced to below 65 nm, and can be as low as 20 nm, thereby reducing the series resistance of the battery, increasing the fill factor of the battery, reducing optical losses, and improving the performance of the battery.

[0125] In some embodiments, the electron transport thin film includes at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide, and gallium oxide.

[0126] The electron transport film in this embodiment no longer uses fullerene, which improves the short-circuit current of the battery. The electron transport film can be applied to more types of materials, which improves the flexibility of electron transport film material selection. By selecting suitable materials for the electron transport film, the performance of electron transport can be optimized, thereby improving the performance of the battery.

[0127] In some embodiments, the hole transport film includes at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide, and antimony oxide.

[0128] The hole transport film in this embodiment is not limited to nickel oxide, which improves the flexibility of hole transport film material selection. By selecting a suitable material for the hole transport film, the hole transport performance can be optimized, thereby improving the performance of the battery.

[0129] In some embodiments, the tunneling composite film 22 includes at least one of tin-doped indium oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, and gallium-doped zinc oxide.

[0130] The tunneling composite film 22 in this embodiment is not limited to tin-doped indium oxide, which improves the flexibility of selecting the tunneling composite film 22. By selecting a suitable material for the tunneling composite film 22, the performance of the tunneling composite film 22 can be optimized, thereby improving the performance of the battery.

[0131] In some embodiments, the bottom cell structure 1 includes a bottom electrode 11 , a first carrier transport layer 12 , and a first photoactive layer 13 which are stacked in sequence, and the first photoactive layer 13 is disposed close to the first type semiconductor film 21 in the first tunnel junction 2 .

[0132] The bottom electrode 11 may include one or more of a transparent conductive oxide, a conductive polymer, and a metal electrode. The first carrier transport layer 12 may be a hole transport layer or an electron transport layer. One of the first type semiconductor film 21 and the first carrier transport layer 12 is used for electron transport, and the other is used for hole transport.

[0133] The top cell structure 3 includes a second photoactive layer 31 , a fourth carrier transport layer 32 and a top electrode 33 which are stacked in sequence. The second photoactive layer 31 is disposed close to the second type semiconductor film 23 in the first tunnel junction 2 .

[0134] The fourth carrier transport layer 32 may be a hole transport layer or an electron transport layer. One of the fourth carrier transport layer 32 and the second type semiconductor film 23 is used for electron transport, and the other is used for hole transport. The top electrode 33 may include one or more of a transparent conductive oxide, a conductive polymer, and a metal electrode.

[0135] For example, the first carrier transport layer 12 is a hole transport layer, the first type semiconductor film 21 is an N-type semiconductor film (i.e., an electron transport film), the second type semiconductor film 23 is a P-type semiconductor film (i.e., a hole transport film), and the fourth carrier transport layer 32 is an electron transport layer; the first carrier transport layer 12 is an electron transport layer, the first type semiconductor film 21 is a P-type semiconductor film (i.e., a hole transport film), the second type semiconductor film 23 is an N-type semiconductor film (i.e., an electron transport film), and the fourth carrier transport layer 32 is a hole transport layer.

[0136] The band gap of the second photoactive layer 31 is greater than the band gap of the first photoactive layer 13. The first photoactive layer 13 may be a narrow band gap active layer, which may include one or more of silicon, group III-V semiconductor materials, group II-VI semiconductor materials, perovskite and organic materials. The second photoactive layer 31 may be a wide band gap active layer, which may include perovskite materials. Perovskite materials have the advantages of high absorption coefficient, adjustable band gap, low temperature preparation and high efficiency.

[0137] In some embodiments, the stacked solar cell further includes an intermediate cell structure 4 and a second tunnel junction 5 sequentially located between the first tunnel junction 2 and the top cell structure 3. The second tunnel junction 5 is an atomic layer structure, that is, the second tunnel junction 5 is prepared by an atomic layer deposition process, which improves the uniformity, compactness and optoelectronic stability of the second tunnel junction 5.

[0138] The second tunnel junction 5 has the same structure as the first tunnel junction 2, that is, the second tunnel junction 5 includes a first type semiconductor film, a tunnel composite film and a second type semiconductor film stacked in sequence, wherein the thickness of the second tunnel junction 5 is 20nm-65nm.

[0139] It should be noted that there may be a plurality of intermediate battery structures 4 between the bottom battery structure 1 and the top battery structure 3, and a third tunnel junction is provided between adjacent intermediate battery structures 4, and the third tunnel junction has the same structure as the first tunnel junction 2 and the second tunnel junction 5. The third tunnel junction is an atomic layer structure, which improves the uniformity, compactness and optoelectronic stability of the third tunnel junction.

[0140] In some embodiments, the intermediate cell structure 4 includes a third photoactive layer 41 , and the band gap of the third photoactive layer 41 is larger than the band gap of the first photoactive layer 13 and smaller than the band gap of the second photoactive layer 31 .

[0141] The third photoactive layer 41 may be a medium bandgap active layer, which may include a perovskite material. For example, the bandgap range of the first photoactive layer 13 is 0.9 eV to 1.2 eV, the bandgap range of the third photoactive layer 41 is 1.2 eV to 1.60 eV (excluding 1.2 eV), and the bandgap range of the second photoactive layer 31 is 1.60 eV to 3.0 eV (excluding 1.60 eV).

[0142] In the case where there are multiple intermediate cell structures 4 between the bottom cell structure 1 and the top cell structure 3, the band gap of the third photoactive layer in the multiple intermediate cell structures 4 is greater than the band gap of the first photoactive layer 13, and less than the band gap of the second photoactive layer 31. Moreover, in the direction from the bottom cell structure 1 to the top cell structure 2, the band gap of the third photoactive layer in the multiple intermediate cell structures 4 gradually increases.

[0143] This embodiment superimposes battery structures with different band gaps so that they can absorb photons in the solar spectrum in segments, thereby improving the photoelectric conversion efficiency and thus breaking through the theoretical efficiency limit of a single material.

[0144] According to the stacked solar cell of the present application, the first tunnel junction 2 is an atomic layer structure, that is, the first type semiconductor film 21, the tunnel composite film 22 and the second type semiconductor film 23 in the first tunnel junction 2 are all prepared by an atomic layer deposition process, which simplifies the preparation process, improves the preparation efficiency, reduces the process cost, and improves the uniformity, density and optoelectronic stability of the first tunnel junction 2.

[0145] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0146] In the description of the present application, “plurality” means two or more.

[0147] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0148] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for preparing a stacked solar cell, characterized in that: include: forming a bottom battery structure; A first tunnel junction is formed on one side of the bottom battery structure by an atomic layer deposition process, wherein the first tunnel junction comprises a first type semiconductor film, a tunnel composite film, and a second type semiconductor film which are sequentially stacked, wherein one of the first type semiconductor film and the second type semiconductor film is an electron transport film, and the other is a hole transport film; A top cell structure is formed on a side of the first tunneling junction facing away from the bottom cell structure.

2. The method for preparing a stacked solar cell according to claim 1, characterized in that: The thickness of the first tunnel junction is 20nm-65nm.

3. The method for preparing a stacked solar cell according to claim 1, characterized in that: The method for forming each thin film in the first tunnel junction includes: Alternately introducing a first precursor and a common reactant to allow the first precursor and the common reactant to react to form a thin film; or, First, alternately introduce the second precursor and the common reactant to make the second precursor react with the common reactant, and then alternately introduce the third precursor and the common reactant to make the third precursor react with the common reactant to produce a thin film; or, The fourth precursor and the fifth precursor are introduced alternately with the common reactant, so that the fourth precursor and the fifth precursor react with the common reactant at the same time to form a thin film.

4. The method for preparing a stacked solar cell according to claim 1, characterized in that: The method further comprises: An annealing process is performed after forming the first tunnel junction.

5. The method for preparing a stacked solar cell according to claim 1, characterized in that: The electron transport film comprises at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide and gallium oxide; and / or, The hole transport film comprises at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide and antimony oxide; and / or, The tunneling composite film includes at least one of tin-doped indium oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and gallium-doped zinc oxide.

6. The method for preparing a tandem solar cell according to any one of claims 1 to 5, characterized in that: Before forming a top cell structure on a side of the first tunnel junction facing away from the bottom cell structure, the method further comprises: forming an intermediate cell structure on a side of the first tunnel junction away from the bottom cell structure; An atomic layer deposition process is used to form a second tunnel junction on the side of the middle battery structure away from the first tunnel junction, and the structure of the second tunnel junction is the same as that of the first tunnel junction; the top battery structure is located on the side of the second tunnel junction away from the middle battery structure.

7. A stacked solar cell, characterized in that: include: Bottom battery structure; A first tunnel junction is located on one side of the bottom cell structure; A top cell structure, located on a side of the first tunnel junction away from the bottom cell structure; Among them, the first tunnel junction is an atomic layer structure, and the first tunnel junction includes a first type semiconductor film, a tunneling composite film and a second type semiconductor film which are sequentially stacked between the bottom battery structure and the top battery structure, and one of the first type semiconductor film and the second type semiconductor film is an electron transport film, and the other is a hole transport film.

8. The tandem solar cell according to claim 7, characterized in that: The thickness of the first tunnel junction is 20nm-65nm.

9. The tandem solar cell according to claim 7, characterized in that: The electron transport film comprises at least one of tin oxide, zinc oxide, indium oxide, titanium oxide, chromium oxide and gallium oxide; and / or, The hole transport film comprises at least one of nickel oxide, copper oxide, cobalt oxide, vanadium oxide, chromium oxide and antimony oxide; and / or, The tunneling composite film includes at least one of tin-doped indium oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and gallium-doped zinc oxide.

10. The tandem solar cell according to claim 7, characterized in that: The bottom cell structure comprises a bottom electrode, a first carrier transport layer and a first photoactive layer stacked in sequence, and the top cell structure comprises a second photoactive layer, a fourth carrier transport layer and a top electrode stacked in sequence; The first photoactive layer is disposed close to the first type semiconductor film in the first tunnel junction, and the second photoactive layer is disposed close to the second type semiconductor film in the first tunnel junction; the band gap of the second photoactive layer is greater than the band gap of the first photoactive layer.

11. The tandem solar cell according to claim 10, characterized in that: The tandem solar cell further comprises an intermediate cell structure and a second tunneling junction alternately arranged between the first tunneling junction and the top cell structure; The second tunneling junction is an atomic layer structure, and the structure of the second tunneling junction is the same as that of the first tunneling junction.

12. The tandem solar cell according to claim 11, characterized in that: The intermediate cell structure includes a third photoactive layer, wherein a band gap of the third photoactive layer is larger than a band gap of the first photoactive layer and smaller than a band gap of the second photoactive layer.

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