Solar cell structure and solar cell

Abstract

The utility model discloses a solar cell structure and a solar cell. The solar cell structure comprises a hole transport layer, a perovskite light absorption layer, an electron transport layer and an electron transport buffer layer, the perovskite light absorption layer is located on one side of the hole transport layer; the electron transport layer is located on the side, away from the hole transport layer, of the perovskite light absorption layer; the electron transport buffer layer is located on the side, away from the perovskite light absorption layer, of the electron transport layer; the electron transmission buffer layer comprises a first indium tungsten oxide thin film. Therefore, by adopting the indium tungsten oxide thin film as at least part of the electron transmission buffer layer, the service life of the solar cell structure can be prolonged, and the stability of the solar cell structure can be improved; moreover, the solar cell structure also can reduce the manufacturing time of the electron transmission buffer layer, reduces the manufacturing cost of the electron transmission buffer layer, and facilitates the large-scale production of the perovskite solar cell.

Description

Technical Field

[0001] This disclosure relates to a solar cell structure and a solar cell. Background Technology

[0002] With the changing global energy landscape, green energy, especially photovoltaic solar energy technology, is gaining market favor in order to reduce greenhouse gas and other harmful emissions. Perovskite solar cells are a new type of third-generation solar cell, characterized by high efficiency, low cost, and flexibility, and are considered one of the important development directions in the photovoltaic field.

[0003] The working principle of perovskite solar cells is based on the separation and transport of photogenerated charge carriers. When sunlight shines on the perovskite light-absorbing layer, the photon energy excites electrons in the perovskite material to the conduction band, while leaving holes in the valence band, forming electron-hole pairs (excitons). These excitons dissociate into free electrons and holes under thermal influence, which are then collected by the electron transport layer (ETL) and hole transport layer (HTL), respectively, and transported to an external circuit to form an electric current. Utility Model Content

[0004] This disclosure provides a solar cell structure, a method for fabricating the same, and a solar cell. By employing an indium tungsten oxide thin film as at least a portion of the electron transport buffer layer, the solar cell structure can improve its lifespan and stability; furthermore, the solar cell structure can reduce the fabrication time of the electron transport buffer layer and lower its fabrication cost, thereby facilitating the large-scale production of perovskite solar cells.

[0005] At least one embodiment of this disclosure provides a solar cell structure comprising: a hole transport layer; a perovskite light-absorbing layer located on one side of the hole transport layer; an electron transport layer located on the side of the perovskite light-absorbing layer away from the hole transport layer; and an electron transport buffer layer located on the side of the electron transport layer away from the perovskite light-absorbing layer; wherein the electron transport buffer layer comprises a first indium tungsten oxide thin film.

[0006] For example, in a solar cell structure provided in one embodiment of this disclosure, the LUMO energy level of the first indium tungsten oxide thin film ranges from -3.2 eV to -3.6 eV, and the HOMO energy level of the first indium tungsten oxide thin film ranges from -7.1 eV to -7.5 eV.

[0007] For example, in a solar cell structure provided in an embodiment of this disclosure, the electron transport buffer layer includes a first sub-buffer layer and a second sub-buffer layer, the second sub-buffer layer being located on the side of the first sub-buffer layer away from the electron transport layer, the first sub-buffer layer including a tin oxide film, and the second sub-buffer layer including a first indium tungsten oxide film.

[0008] For example, in a solar cell structure provided in one embodiment of this disclosure, the thickness of the second sub-buffer layer is greater than the thickness of the first sub-buffer layer.

[0009] For example, in a solar cell structure provided in one embodiment of this disclosure, the thickness of the first sub-buffer layer ranges from 8 to 20 nanometers, and the thickness of the second sub-buffer layer ranges from 30 to 50 nanometers.

[0010] For example, in a solar cell structure provided in one embodiment of this disclosure, the sheet resistance of the first indium tungsten oxide thin film ranges from 1000Ω / sq to 2000Ω / sq.

[0011] For example, in a solar cell structure provided in one embodiment of this disclosure, the refractive index of the first indium tungsten oxide thin film ranges from 2.0 to 2.3.

[0012] For example, in a solar cell structure provided in one embodiment of this disclosure, the refractive index of the first indium tungsten oxide thin film is greater than the refractive index of the electron transport layer and the refractive index of the perovskite light-absorbing layer.

[0013] For example, in a solar cell structure provided in one embodiment of this disclosure, the first indium tungsten oxide thin film includes a plurality of sub-indium tungsten oxide thin films stacked together, and the LUMO energy levels of the plurality of sub-indium tungsten oxide thin films gradually decrease in the direction away from the electron transport layer.

[0014] For example, a solar cell structure provided in one embodiment of this disclosure further includes: a first electrode layer located on the side of the electron transport buffer layer away from the electron transport layer.

[0015] For example, in a solar cell structure provided in one embodiment of this disclosure, the first electrode layer includes a second indium tungsten oxide thin film.

[0016] For example, in a solar cell structure provided in one embodiment of this disclosure, the thickness of the first indium tungsten oxide thin film ranges from 30 to 50 nanometers, and the thickness of the second indium tungsten oxide thin film ranges from 30 to 50 nanometers.

[0017] For example, in a solar cell structure provided in one embodiment of this disclosure, the oxygen vacancy content of the second indium tungsten oxide thin film is less than that of the oxygen vacancy content of the first indium tungsten oxide thin film.

[0018] For example, in a solar cell structure provided in one embodiment of this disclosure, the LUMO level of the second indium tungsten oxide film is deeper than the LUMO level of the first indium tungsten oxide film, and the HOMO level of the second indium tungsten oxide film is deeper than the HOMO level of the first indium tungsten oxide film.

[0019] For example, in a solar cell structure provided in one embodiment of this disclosure, the sheet resistance of the second indium tungsten oxide thin film is less than that of the first indium tungsten oxide thin film.

[0020] For example, in a solar cell structure provided in an embodiment of this disclosure, the first electrode layer includes a first sub-electrode layer and a second sub-electrode layer, the second sub-electrode layer is located on the side of the first sub-electrode layer away from the electron transport buffer layer, the first sub-electrode layer includes a second indium tungsten oxide thin film, and the second sub-electrode layer includes a conductive metal.

[0021] For example, in a solar cell structure provided in an embodiment of this disclosure, the first electrode layer includes a first sub-electrode layer and a second sub-electrode layer, the second sub-electrode layer is located on the side of the first sub-electrode layer away from the electron transport buffer layer, the first sub-electrode layer includes indium tin oxide or fluorine-doped tin oxide, and the second sub-electrode layer includes a conductive metal.

[0022] For example, in a solar cell structure provided in one embodiment of this disclosure, the perovskite light-absorbing layer is disposed in contact with the electron transport layer.

[0023] For example, a solar cell structure provided in one embodiment of this disclosure further includes a passivation layer located between the perovskite light-absorbing layer and the electron transport layer.

[0024] For example, a solar cell structure provided in one embodiment of this disclosure further includes a second electrode layer located on the side of the hole transport layer away from the perovskite light-absorbing layer.

[0025] For example, in a solar cell structure provided in one embodiment of this disclosure, the first indium tungsten oxide thin film in the electron transport buffer layer is fabricated using a reactive plasma deposition process.

[0026] At least one embodiment of this disclosure also provides a solar cell comprising the solar cell structure described in any of the preceding claims.

[0027] At least one embodiment of this disclosure also provides a method for fabricating a solar cell structure, comprising: forming a hole transport layer; forming a perovskite light-absorbing layer on one side of the hole transport layer; forming an electron transport layer on the side of the perovskite light-absorbing layer away from the hole transport layer; and forming an electron transport buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer; wherein the electron transport buffer layer comprises a first indium tungsten oxide thin film, the LUMO energy level of the first indium tungsten oxide thin film is in the range of -3.2 eV to -3.6 eV, and the HOMO energy level of the first indium tungsten oxide thin film is in the range of -7.1 eV to -7.5 eV.

[0028] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, forming an electron transport buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer includes: forming the first indium tungsten oxide thin film on the side of the electron transport layer away from the perovskite light-absorbing layer using a reactive plasma deposition process.

[0029] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, forming an electron transport buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer includes: forming a tin oxide film on the side of the electron transport layer away from the perovskite light-absorbing layer as a first sub-buffer layer; and forming a first indium tungsten oxide film on the side of the first sub-buffer layer away from the electron transport layer as a second sub-buffer layer.

[0030] For example, a method for fabricating a solar cell structure provided in one embodiment of this disclosure further includes forming a first electrode layer on the side of the electron transport buffer layer away from the electron transport layer.

[0031] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, forming a first electrode layer on the side of the electron transport buffer layer away from the electron transport layer includes forming a second indium tungsten oxide thin film on the side of the electron transport buffer layer away from the electron transport layer.

[0032] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, forming a first electrode layer on the side of the electron transport buffer layer away from the electron transport layer includes: forming a second indium tungsten oxide thin film on the side of the electron transport buffer layer away from the electron transport layer as a first sub-electrode layer; and forming a conductive metal on the side of the second indium tungsten oxide away from the electron transport buffer layer as a second sub-electrode layer, wherein the first electrode layer includes the first sub-electrode layer and the second sub-electrode layer.

[0033] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, the oxygen vacancy content in the second indium tungsten oxide thin film is less than the oxygen vacancy content in the first indium tungsten oxide thin film.

[0034] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, the oxygen content in the process atmosphere for forming the second indium tungsten oxide thin film is greater than the oxygen content in the process atmosphere for forming the second indium tungsten oxide thin film.

[0035] For example, in a method for fabricating a solar cell structure provided in an embodiment of this disclosure, after the perovskite light-absorbing layer is formed, the electron transport layer is formed directly on the perovskite light-absorbing layer.

[0036] For example, a method for fabricating a solar cell structure provided in one embodiment of this disclosure further includes: after forming the perovskite light-absorbing layer, forming a passivation layer on the perovskite light-absorbing layer. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure.

[0038] Figure 1 This is a schematic diagram of a solar cell structure provided in one embodiment of the present disclosure;

[0039] Figure 2 This is a schematic diagram of another solar cell structure provided in an embodiment of the present disclosure;

[0040] Figure 3 Comparative graphs of parameters such as device efficiency are shown for several solar cell structures provided according to embodiments of the present disclosure;

[0041] Figure 4A A schematic diagram showing the copper ion intensity in the perovskite light-absorbing layer before aging, according to an embodiment of this disclosure and a conventional solar cell structure.

[0042] Figure 4B A schematic diagram showing the copper ion intensity in the perovskite light-absorbing layer after aging, according to an embodiment of this disclosure and a conventional solar cell structure.

[0043] Figure 5 A flowchart illustrating a method for fabricating a solar cell structure according to an embodiment of this disclosure;

[0044] Figure 6This is a graph showing the relationship between the oxygen content in the process atmosphere and the energy level distribution of the formed indium tungsten oxide film when indium tungsten oxide is fabricated using reactive plasma deposition.

[0045] Figure 7 This is a graph showing the relationship between the oxygen content in the process atmosphere and the sheet resistance of the formed indium tungsten oxide film when using reactive plasma deposition.

[0046] Figure 8 This is a graph showing the relationship between the oxygen content in the process atmosphere and the conductivity of the resulting indium tungsten oxide film when indium tungsten oxide is fabricated using reactive plasma deposition.

[0047] Figure 9 This is a graph showing the relationship between the oxygen content in the process atmosphere and the refractive index of the formed indium tungsten oxide film when indium tungsten oxide is fabricated using reactive plasma deposition.

[0048] Figure 10 This is a schematic diagram of another solar cell structure provided in an embodiment of the present disclosure;

[0049] Figure 11 This is a schematic diagram of another solar cell structure provided in an embodiment of the present disclosure;

[0050] Figure 12 Comparison charts of parameters such as device efficiency are shown for several other solar cell structures provided according to embodiments of this disclosure;

[0051] Figure 13 This is a schematic diagram of another solar cell structure provided in an embodiment of the present disclosure;

[0052] Figure 14 This is a schematic diagram of another solar cell structure provided in an embodiment of the present disclosure;

[0053] Figure 15 Comparison charts of parameters such as device efficiency are shown for several other solar cell structures provided according to embodiments of this disclosure;

[0054] Figure 16 A schematic diagram of another solar cell structure provided in an embodiment of this disclosure; and

[0055] Figure 17 This is a schematic diagram of the structure of a solar cell provided in one embodiment of the present disclosure. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the described embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0057] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0058] Perovskite solar cells, as the third generation of photovoltaic cells, possess advantages such as high theoretical conversion efficiency, short production process, low cost, diverse application scenarios, and strong low-light response, making them one of the development directions of the photovoltaic industry. In perovskite solar cells, the electron transport layer (ETL) primarily extracts photogenerated electrons from the perovskite light-absorbing layer and transports them to the cathode. An electron transport buffer layer can be placed on the side of the electron transport layer away from the perovskite light-absorbing layer. This buffer layer plays a crucial role in blocking holes, extracting electrons, and buffering the impact of the cathode formation process on the electron transport layer.

[0059] In their research, the inventors of this application discovered that conventional perovskite solar cells use atomic deposition to form tin oxide (SnO2) as an electron transport buffer layer. In the process of forming tin oxide, a precursor, tetra(dimethylamino)tin (TDMASn), needs to be introduced first. TDMASn readily penetrates into the perovskite light-absorbing layer, and as a Lewis acid, it can react with the perovskite material, causing a change in its valence state (Sn). 4+ →Sn 2+ In perovskite materials, the A-site cations are deprotonated, and methylamine gas escapes during aging. This weakens the bonding force between the lead iodide framework and organic cations in the perovskite crystal, making it difficult for the crystal lattice to maintain a stable cubic structure. This induces the α-cubic phase to δ phase transformation, causing the perovskite material to decompose and affecting the long-term lifespan stability of the battery.

[0060] On the other hand, the atomic deposition process for forming tin oxide, at temperatures of approximately 80°C to 100°C, may affect the perovskite and electron transport layers (e.g., C). 60Secondary heating can cause adverse effects. Furthermore, the atomic deposition process for forming tin oxide is time-consuming, severely limiting production speed. Additionally, tetra(dimethylamino)tin itself is expensive, further restricting mass production of perovskite solar cells. To address these issues, the inventors of this application have devised an improvement to the electron transport buffer layer in perovskite solar cells, thereby solving at least one of the aforementioned problems.

[0061] At least one embodiment of this disclosure provides a solar cell structure and a method for fabricating the same. The solar cell structure includes a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electron transport buffer layer. The hole transport layer is located on one side of the substrate; the perovskite light-absorbing layer is located on the side of the hole transport layer away from the substrate; the electron transport layer is located on the side of the perovskite light-absorbing layer away from the hole transport layer; and the electron transport buffer layer is located on the side of the electron transport layer away from the perovskite light-absorbing layer. The electron transport buffer layer includes a first indium tungsten oxide (ITO) thin film. Therefore, by using an ITO thin film as at least a portion of the electron transport buffer layer, this solar cell structure can reduce or even avoid the adverse effects of tin oxide precursors on the perovskite light-absorbing layer and the electron transport layer, thereby improving the lifespan and stability of the solar cell structure. Furthermore, this solar cell structure can reduce the fabrication time of the electron transport buffer layer and lower its fabrication cost, thus facilitating the mass production of perovskite solar cells.

[0062] At least one embodiment of this disclosure also provides a solar cell including the solar cell structure described above. Therefore, this solar cell has a long lifespan and high stability, and also has shorter manufacturing time and lower manufacturing costs, facilitating mass production.

[0063] The solar cell structure, its manufacturing method, and the solar cell provided in the embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0064] One embodiment of this disclosure provides a solar cell structure; Figure 1 This is a schematic diagram of a solar cell structure provided in one embodiment of the present disclosure. Figure 1 As shown, the solar cell structure 100 includes a substrate 110, a hole transport layer 120, a perovskite light-absorbing layer 130, an electron transport layer 140, and an electron transport buffer layer 150. The hole transport layer 120 is located on one side of the substrate 110. The perovskite light-absorbing layer 130 is located on the side of the hole transport layer 120 away from the substrate 110. The electron transport layer 140 is located on the side of the perovskite light-absorbing layer 130 away from the hole transport layer 120 and is used to extract photogenerated electrons from the perovskite light-absorbing layer 130. The electron transport buffer layer 150 is located on the side of the electron transport layer 140 away from the perovskite light-absorbing layer 130, and the electron transport buffer layer 150 includes a first indium tungsten oxide thin film 190A.

[0065] like Figure 1 As shown, the perovskite light-absorbing layer 130 is configured to absorb photons and generate photogenerated carriers; the electron transport layer 140 is configured to extract photogenerated electrons from the perovskite light-absorbing layer 130; and the electron transport buffer layer 150 is configured to block holes, extract electrons, and play a buffering role in the subsequent electrode formation process to prevent the electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer.

[0066] The LUMO energy level of the aforementioned first indium tungsten oxide (ITO) thin film ranges from -3.2 eV to -3.6 eV, and the HOMO energy level ranges from -7.1 eV to -7.5 eV. Therefore, the LUMO energy level of the first ITO thin film is relatively close to the energy level of the electron transport layer (approximately -4.2 eV), facilitating the extraction and transport of electrons from the electron transport layer. On the other hand, the HOMO energy level of the first ITO thin film, ranging from -7.1 eV to -7.5 eV, is deeper, thus facilitating the blocking of holes. It should be noted that the LUMO and HOMO energy levels of the first ITO thin film can be controlled by controlling the oxygen content in the process atmosphere during reactive plasma deposition. It should also be noted that the oxygen content mentioned above refers to volume content, i.e., the proportion of oxygen volume to the total volume of the process atmosphere.

[0067] In the solar cell structure provided in this embodiment, since the electron transport buffer layer includes a first indium tungsten oxide (ITO) thin film, the solar cell structure reduces the fabrication time and cost of the electron transport buffer layer by using ITO as at least a portion of it, thus facilitating the large-scale production of perovskite solar cells. It should be noted that even if only a portion of the electron transport buffer layer is made using ITO, the reduced tin oxide thickness in this case also contributes to reducing the fabrication time and cost. Furthermore, compared to the tin oxide thin film, the first ITO thin film has higher density, thus providing better buffering in subsequent electrode formation processes. In other words, the first ITO thin film better prevents the subsequent electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer. On the other hand, since the electron transport buffer layer includes the first ITO thin film, the solar cell structure can reduce or even avoid the adverse effects of the tin oxide precursor on the perovskite light-absorbing layer and electron transport layer, thereby improving the lifespan and stability of the solar cell structure.

[0068] It should be noted that in the conventional manufacturing process of perovskite solar cell structures, if the electron transport buffer layer is entirely made of tin oxide, the fabrication time using atomic deposition is approximately 15 minutes. In the solar cell structure provided in this disclosure, if the electron transport buffer layer is entirely made of indium tungsten oxide thin film, the fabrication time using reactive plasma deposition (RPD) is only 5 minutes. Therefore, the solar cell structure provided in this disclosure can significantly reduce the fabrication time of the electron transport buffer layer.

[0069] It should be noted that the unit price of tetra(dimethylamino)tin, the precursor for forming tin oxide, is currently about 10 times the cost of forming indium tungsten oxide. Therefore, the solar cell structure provided in this disclosure can significantly reduce the manufacturing cost of the electron transport buffer layer.

[0070] In some examples, the refractive index of the first indium tungsten oxide film ranges from 2.0 to 2.3, for example, 2.1 or 2.2. Due to the higher density of the indium tungsten oxide film, its refractive index is also relatively higher, increasing from 1.8 for the tin oxide film to 2.1 or 2.2.

[0071] In some examples, the refractive index of the first indium tungsten oxide film is also greater than that of the electron transport layer, and the refractive index of the first indium tungsten oxide film is also greater than that of the perovskite light-absorbing layer.

[0072] In some examples, the sheet resistance of the first indium tungsten oxide thin film ranges from 1000 Ω / sq to 2000 Ω / sq, exhibiting a relatively low sheet resistance. Therefore, this first indium tungsten oxide thin film not only blocks holes but also facilitates electron transport.

[0073] It should be noted that the materials of the perovskite light-absorbing layer mentioned above may include organic perovskite materials or inorganic halide perovskite materials with a perovskite structure, which can efficiently absorb sunlight and generate photogenerated carriers.

[0074] For example, organic perovskite materials may include at least one of methylamine lead iodide (CH3NH3PbI3) and formamidinium lead iodide (HC(NH2)2PbI3), while inorganic halogen perovskite materials may include cesium lead iodide (CsPbI3) and cesium lead bromide (CsPbI3). 3-x Br x It is selected from at least one of lead chloride (CsPbCl3). Of course, the above-mentioned materials are merely examples, and the embodiments disclosed herein include, but are not limited to, those of other photovoltaic power generation materials with perovskite structures.

[0075] For example, the chemical formula of the perovskite light-absorbing layer material mentioned above can be ABX3, where A can be a monovalent cation, which can include one or more of cesium (Cs), rubidium (Rb), methylamino (CH3NH3, MA), and formamidinyl (CH(NH)NH2, FA); B can be a divalent cation, which can include one or more of lead (Pb), copper (Cu), zinc (Zn), gallium (Ga), tin (Sn), and calcium (Ca); and X can be a monovalent anion, which can include one or more of iodine (I), bromine (Br), chlorine (Cl), fluorine (F), thiocyanate ion (SCN-), tetrafluoroborate ion (BF4-), and hexafluorophosphate ion (PF6-).

[0076] For example, the material of the hole transport layer 120 mentioned above includes nickel oxide (NiO). x Of course, the embodiments disclosed herein include, but are not limited to, the material of the hole transport layer may also be 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), polytriarylamine (PTAA), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and other organic hole transport materials, or inorganic hole transport materials such as copper iodide, copper thiocyanate, cobalt oxide and vanadium pentoxide.

[0077] For example, the material of the electron transport layer 140 described above can be fullerene (C 60 Of course, the embodiments disclosed herein include, but are not limited to, other electron transport materials, such as PCBM([6,6]-phenyl-C); 61 methyl butyrate, Phenyl-C 61 -butyric acid methyl ester).

[0078] In some examples, such as Figure 1As shown, the electron transport buffer layer 150 consists only of a first indium tungsten oxide thin film 190A, meaning that the electron transport buffer layer 150 is entirely made of indium tungsten oxide. In this case, the solar cell structure can minimize the fabrication time and cost of the electron transport buffer layer. Furthermore, since the electron transport buffer layer is entirely made of indium tungsten oxide, the precursor tetra(dimethylamino)tin (TDMASn) is no longer needed in the fabrication process, thus preventing TDMASn from penetrating into the perovskite light-absorbing layer and reacting with the perovskite material to induce crystal decomposition. Therefore, this solar cell structure can significantly improve the product's lifespan. In addition, compared to the tin oxide thin film, the first indium tungsten oxide thin film has higher density, thus providing better buffering in subsequent electrode formation processes. In other words, the first indium tungsten oxide thin film can better prevent subsequent electrode formation processes from adversely affecting the electron transport layer and the perovskite light-absorbing layer. On the other hand, since the electron transport buffer layer is made entirely of indium tungsten oxide, the secondary heating effect on the perovskite light-absorbing layer and electron transport layer caused by the high temperature of the atomic deposition process can be avoided.

[0079] It should be noted that in the typical manufacturing process of perovskite solar cells, if the electron transport buffer layer is entirely made of tin oxide, the atomic deposition process requires a process temperature of 80°C to 100°C, and this process needs to stabilize. Therefore, the fabrication time for the electron transport buffer layer is approximately 15 minutes, and the relatively high process temperature can also have secondary effects on the perovskite light-absorbing layer and the electron transport layer. In the solar cell structure of this example, the electron transport buffer layer is entirely made of indium tungsten oxide thin film. The reactive plasma deposition process for fabricating the electron transport buffer layer only takes 5 minutes, thereby reducing the fabrication time of the electron transport buffer layer by 67% and avoiding the secondary effects of high process temperature on the perovskite light-absorbing layer and the electron transport layer.

[0080] It should be noted that currently, the formation of tin oxide requires tetra(dimethylamino)tin as a precursor, and the unit price of tetra(dimethylamino)tin is relatively high, about 10 times the cost of forming indium tungsten oxide. Therefore, the solar cell structure provided in this disclosure can significantly reduce the manufacturing cost of the electron transport buffer layer, thereby reducing the manufacturing time of the electron transport buffer layer by 90%. It should also be noted that the target ingot raw materials used to form indium tungsten oxide are mostly doped inorganic materials, which are inexpensive. For example, the target ingot raw materials used to form indium tungsten oxide include tungsten oxide target ingots and indium oxide target ingots.

[0081] In some examples, such as Figure 1As shown, the solar cell structure 100 further includes a first electrode layer 160 located on the side of the electron transport buffer layer 150 away from the electron transport layer 140. The first electrode layer 160 includes a first sub-electrode layer 161 and a second sub-electrode layer 162; the second sub-electrode layer 162 is located on the side of the first sub-electrode layer 161 away from the electron transport buffer layer 150. The first sub-electrode layer 161 comprises a transparent conductive oxide, and the second sub-electrode layer 162 comprises a conductive metal. Therefore, the first sub-electrode layer can improve the work function matching between the metal electrode and the electron transport buffer layer, reduce the contact resistance between the metal electrode and the electron transport buffer layer, thereby improving the electron transport efficiency. In addition, the first sub-electrode layer can also prevent the diffusion of metal ions in the metal electrode. Of course, embodiments of this disclosure include, but are not limited to, the above-described first electrode layer may also only include a second sub-electrode layer made of conductive metal.

[0082] For example, the conductive metal mentioned above can be copper, silver, or other metals with high conductivity. Of course, the embodiments disclosed herein include, but are not limited to, other types of conductive metal materials.

[0083] In some examples, such as Figure 1 As shown, in this solar cell structure 100, the electron transport layer 140 is directly contacted with the perovskite light-absorbing layer 130. Therefore, this solar cell structure does not have a passivation layer between the electron transport layer and the perovskite light-absorbing layer, resulting in a smaller thickness. Furthermore, this solar cell structure avoids the problems of reduced lifespan and stability caused by water absorption by the passivation layer.

[0084] In some examples, such as Figure 1 As shown, the solar cell structure 100 also includes a second electrode layer 180 located between the substrate 110 and the hole transport layer 120.

[0085] For example, the substrate 110 can be made of glass, and the second electrode layer 180 can be made of indium tin oxide or fluorine-doped tin oxide. Of course, embodiments of this disclosure include, but are not limited to, other materials may also be used for the substrate and the second electrode layer.

[0086] Figure 2 This is a schematic diagram of another solar cell structure provided in one embodiment of the present disclosure. Figure 1 The solar cell structure shown is different, Figure 2 The solar cell structure 100 shown also includes a passivation layer 170 located between the perovskite light-absorbing layer 130 and the electron transport layer 140. The passivation layer 170 can passivate surface defects of the perovskite light-absorbing layer and effectively increase the open-circuit voltage (Voc), thereby improving the power conversion efficiency (PCE).

[0087] For example, the material of the passivation layer 170 described above can be lithium fluoride (LiF). Of course, embodiments disclosed herein include, but are not limited to, this.

[0088] Figure 3 Comparative graphs of parameters such as device efficiency are shown for several solar cell structures provided according to embodiments of this disclosure. For example... Figure 3 As shown, Example 1 uses the following... Figure 1 The solar cell structure shown in Example 2 uses the following... Figure 2 The solar cell structure is shown. Example 1 includes several sub-examples with different thicknesses of the first indium tungsten oxide film, i.e., different thicknesses of the electron transport buffer layer. The thicknesses of the first indium tungsten oxide film in the sub-examples of Example 1 include 20 nm, 40 nm, 70 nm, and 100 nm. The thickness of the first indium tungsten oxide film in Example 2 is 40 nm.

[0089] like Figure 3 As shown, in a solar cell structure without a passivation layer, the power conversion efficiency of the solar cell structure first increases and then decreases with the increase of the thickness of the first indium tungsten oxide thin film. The optimal thickness is 40 nanometers, at which point the power conversion efficiency reaches 17.66%. In this case, because the solar cell structure uses the first indium tungsten oxide thin film as an electron transport buffer layer and does not have a passivation layer, the solar cell structure has a long service life and slow efficiency degradation. Under the conditions of dual 85 (referring to a constant temperature and humidity environment of 85°C and 85% humidity), the T90 lifetime (the time it takes for the power conversion efficiency of the solar cell to drop to 95% of its initial value) can reach 1000 hours. It should be noted that when the thickness of the first indium tungsten oxide thin film is 20 nanometers, 70 nanometers, and 100 nanometers, the power conversion efficiencies of the solar cell structure are 17.59%, 17.43%, and 17.26%, respectively.

[0090] like Figure 3 As shown, in a solar cell structure with a passivation layer, the open-circuit voltage can be increased by a maximum of 0.03V, the power conversion efficiency can be increased by a maximum of 1.59%, and the maximum power conversion efficiency can reach 19.25%. Furthermore, under dual 85 conditions, the T90 lifetime is not significantly reduced. Therefore, compared to a solar cell structure without a passivation layer, a solar cell structure with a passivation layer can improve the power conversion efficiency, but it will result in a certain loss of lifespan.

[0091] like Figure 3As shown, in a solar cell structure without a passivation layer, the open-circuit voltage of the solar cell structure first increases and then decreases with the increase of the thickness of the first indium tungsten oxide film. When the thickness of the first indium tungsten oxide film is 20 nanometers, the open-circuit voltage of the solar cell structure is 1.018V; when the thickness of the first indium tungsten oxide film is 40 nanometers, the open-circuit voltage of the solar cell structure is 1.068V; when the thickness of the first indium tungsten oxide film is 70 nanometers, the open-circuit voltage of the solar cell structure is 1.057V; and when the thickness of the first indium tungsten oxide film is 100 nanometers, the open-circuit voltage of the solar cell structure is 1.011V.

[0092] like Figure 3 As shown, in a solar cell structure with a passivation layer, when the thickness of the first indium tungsten oxide thin film is 40 nanometers, the open-circuit voltage of the solar cell structure is 1.041V.

[0093] like Figure 3 As shown, in a solar cell structure without a passivation layer, the fill factor of the solar cell structure first increases and then decreases with the increase of the thickness of the first indium tungsten oxide film. When the thickness of the first indium tungsten oxide film is 20 nanometers, the fill factor of the solar cell structure is 61.96%; when the thickness of the first indium tungsten oxide film is 40 nanometers, the fill factor of the solar cell structure is 70.37%; when the thickness of the first indium tungsten oxide film is 70 nanometers, the fill factor of the solar cell structure is 72.64%; and when the thickness of the first indium tungsten oxide film is 100 nanometers, the fill factor of the solar cell structure is 72.71%.

[0094] like Figure 3 As shown, in a solar cell structure with a passivation layer, when the thickness of the first indium tungsten oxide thin film is 40 nanometers, the fill factor of the solar cell structure is 70.79%.

[0095] Figure 4A A schematic diagram showing the copper ion intensity in the perovskite light-absorbing layer before aging, according to an embodiment of this disclosure and a conventional solar cell structure. Figure 4B This is a schematic diagram showing the copper ion intensity in the perovskite light-absorbing layer after aging, compared to a conventional solar cell structure provided in an embodiment of this disclosure. Figure 4A This shows the condition before aging. Figure 4B The condition after aging is shown.

[0096] like Figure 4A and Figure 4BAs shown, in the dual 85-year aging stability test, the copper ion (Cu+) intensity of the solar cell structure provided in this embodiment did not increase significantly before and after aging, while the copper ion (Cu+) intensity of a typical solar cell structure using tin oxide as an electron transport buffer layer increased significantly after aging. This indicates that after aging, copper ions (Cu+) migrate into the perovskite light-absorbing layer, causing a reaction between iodine ions (I-) and copper ions (Cu+) in the perovskite light-absorbing layer, thus compromising device stability. The electron transport buffer layer provided in this embodiment effectively blocks the migration of copper ions (Cu+).

[0097] At least one embodiment of this disclosure also provides a method for fabricating a solar cell structure. Figure 5 This is a flowchart illustrating a method for fabricating a solar cell structure according to an embodiment of this disclosure. Figure 5 As shown, the method for fabricating this solar cell structure includes the following steps S101-S104.

[0098] Step S101: Form a hole transport layer on the substrate.

[0099] For example, a 20-nanometer-thick nickel oxide film can be formed on a substrate using a physical vapor deposition (PVD) process to serve as a hole transport layer.

[0100] For example, the substrate described above can be a glass substrate; the surface of the substrate away from the hole transport layer can serve as the light-incident surface of the solar cell structure.

[0101] Step S102: Form a perovskite light-absorbing layer on the side of the hole transport layer away from the substrate.

[0102] For example, a perovskite precursor solution can be coated on top of the hole transport layer, and after vacuum-controlled drying (VCD) and hot plate baking (HP) processes, a 500-nanometer perovskite film can be formed as a perovskite light-absorbing layer.

[0103] Step S103: Form an electron transport layer on the side of the perovskite light-absorbing layer away from the hole transport layer.

[0104] For example, after the perovskite light-absorbing layer is formed, the electron transport layer is formed directly on the perovskite light-absorbing layer. For example, a 20-nanometer-thick fullerene (C) layer is deposited on the side of the perovskite light-absorbing layer away from the hole transport layer. 60 It serves as an electron transport layer.

[0105] Step S104: An electron transport buffer layer is formed on the side of the electron transport layer away from the perovskite light-absorbing layer. The electron transport buffer layer includes a first indium tungsten oxide thin film. The LUMO energy level of the first indium tungsten oxide thin film has a range of -3.2eV to -3.6eV, and the HOMO energy level of the first indium tungsten oxide thin film has a range of -7.1eV to -7.5eV.

[0106] In the method for fabricating a solar cell structure provided in this disclosure, since the electron transport buffer layer includes a first indium tungsten oxide (ITO) thin film, the solar cell structure uses an ITO thin film as at least a portion of the electron transport buffer layer, thereby reducing the fabrication time and cost of the electron transport buffer layer, which is beneficial for the large-scale production of perovskite solar cells. It should be noted that even if only a portion of the electron transport buffer layer is fabricated using an ITO thin film, the reduced tin oxide thickness in this case also helps to reduce the fabrication time and cost of the electron transport buffer layer. Furthermore, compared to a tin oxide thin film, the first ITO thin film has higher density, thus providing better buffering in subsequent electrode formation processes. In other words, the first ITO thin film can better prevent the subsequent electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer. On the other hand, since the electron transport buffer layer includes a first ITO thin film, the solar cell structure can reduce or even avoid the adverse effects of tin oxide precursors on the perovskite light-absorbing layer and the electron transport layer, thereby improving the lifespan and stability of the solar cell structure.

[0107] In some examples, forming an electron transport buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer includes forming a first indium tungsten oxide thin film on the side of the electron transport layer away from the perovskite light-absorbing layer using a reactive plasma deposition process. Therefore, this first indium tungsten oxide thin film has a faster formation time and better film quality.

[0108] Figure 6 This diagram illustrates the relationship between the oxygen content in the process atmosphere and the energy level distribution of the formed indium tungsten oxide film during reactive plasma deposition (RPD). Figure 6As shown, when tungsten oxide and indium oxide are used as target materials and argon, hydrogen and oxygen are used as process atmospheres, the LUMO and HOMO energy levels of the formed indium tungsten oxide gradually shift downward as the oxygen content in the process atmosphere increases. For example, when the oxygen content is 0%, the LUMO energy level of the formed indium tungsten oxide (ITO) film is -3.28 eV, and the HOMO energy level is -7.14 eV; when the oxygen content is 1%, the LUMO energy level is -3.34 eV, and the HOMO energy level is -7.20 eV; when the oxygen content is 5%, the LUMO energy level is -3.49 eV, and the HOMO energy level is -7.36 eV; and when the oxygen content is 7%, the LUMO energy level is -3.59 eV, and the HOMO energy level is -7.46 eV. Therefore, the energy level distribution of the formed ITO film can be adjusted or controlled by controlling the oxygen content in the process atmosphere during reactive plasma deposition.

[0109] On the other hand, the inventors of this application also noted that the oxygen content in the process atmosphere also affects the sheet resistance, conductivity, and refractive index of the formed indium tungsten oxide thin film.

[0110] Figure 7 This is a graph showing the relationship between the oxygen content in the process atmosphere and the sheet resistance of the formed indium tungsten oxide film when using reactive plasma deposition. Figure 8 This is a graph showing the relationship between the oxygen content in the process atmosphere and the conductivity of the resulting indium tungsten oxide film when indium tungsten oxide is fabricated using reactive plasma deposition. Figure 9 This graph shows the relationship between the oxygen content in the process atmosphere and the refractive index of the formed indium tungsten oxide film during reactive plasma deposition (RPD). It should be noted that the above... Figure 7 and Figure 8 The ordinate has been normalized.

[0111] like Figure 7 As shown, when tungsten oxide and indium oxide are used as target materials, and argon, hydrogen, and oxygen are used as process atmospheres, the sheet resistance of the formed indium tungsten oxide thin film gradually decreases with increasing oxygen content in the process atmosphere. Figure 8 As shown, when tungsten oxide and indium oxide are used as targets, and argon, hydrogen, and oxygen are used as process atmospheres, the conductivity of the formed indium tungsten oxide film gradually increases with the increase of oxygen content in the process atmosphere. Therefore, when the oxygen content is low, the formed indium tungsten oxide film can be used as an electron transport buffer layer, while when the oxygen content is sufficiently high, the formed indium tungsten oxide film can also be used as an electrode.

[0112] like Figure 9 As shown, when using tungsten oxide and indium oxide as targets, and argon, hydrogen, and oxygen as process atmospheres, the refractive index of the formed indium tungsten oxide film initially remains stable and then gradually decreases with increasing oxygen content in the process atmosphere. Since the refractive index of the indium tungsten oxide film can reflect its density or degree of compactness, a low-oxygen-content indium tungsten oxide film with a higher refractive index can be used as an electron transport buffer layer, thus providing a better buffering effect. It should be noted that... Figure 9 The measured refractive index is the refractive index relative to light with a wavelength of 630 nanometers.

[0113] comprehensive Figures 6-9 The parameters of indium tungsten oxide (ITO) formed under different oxygen contents are shown. When ITO is fabricated using reactive plasma deposition, the oxygen content in the process atmosphere can be in the range of 0%-1%, so that the LUMO energy level of the formed ITO film is in the range of -3.28eV to -3.34eV, the HOMO energy level is in the range of -7.14eV to -7.20eV, and the ITO film also has high refractive index and density.

[0114] In some examples, the above-described method for fabricating a solar cell structure further includes forming a first electrode layer on the side of the electron transport buffer layer away from the electron transport layer.

[0115] For example, a sputtering process can be used to form the first electrode layer. This first electrode layer may include a first sub-electrode layer and a second sub-electrode layer; the second sub-electrode layer is located on the side of the first sub-electrode layer away from the electron transport buffer layer. The first sub-electrode layer comprises a transparent conductive oxide, and the second sub-electrode layer comprises a conductive metal. Therefore, the first sub-electrode layer can improve the work function matching between the metal electrode and the electron transport buffer layer, reduce the contact resistance between the metal electrode and the electron transport buffer layer, and thus improve the electron transport efficiency. In addition, the first sub-electrode layer can also prevent the diffusion of metal ions in the metal electrode.

[0116] Thus, the method for fabricating this solar cell structure can be formed. Figure 1 The solar cell structure shown is not limited to this. Of course, embodiments of this disclosure include, but are not limited to, the method for fabricating this solar cell structure, where a perovskite light-absorbing layer can be formed on the side of the hole transport layer away from the substrate, followed by the formation of a passivation layer on the side of the perovskite light-absorbing layer away from the hole transport layer. Thus, the method for fabricating this solar cell structure can form… Figure 2 The solar cell structure shown.

[0117] For example, a 2-nanometer-thick lithium fluoride (LiF) film can be deposited on the surface of the perovskite light-absorbing layer as a passivation layer, and then a 20-nanometer-thick fullerene (C) film can be deposited on the surface of the lithium fluoride (LiF) film. 60 It serves as an electron transport layer.

[0118] At least one embodiment of this disclosure also provides another solar cell structure. Figure 10 This is a schematic diagram of another solar cell structure provided in an embodiment of this disclosure. Figure 10 As shown, the solar cell junction 100 includes a substrate 110, a hole transport layer 120, a perovskite light-absorbing layer 130, an electron transport layer 140, and an electron transport buffer layer 150. The hole transport layer 120 is located on one side of the substrate 110. The perovskite light-absorbing layer 130 is located on the side of the hole transport layer 120 away from the substrate 110. The electron transport layer 140 is located on the side of the perovskite light-absorbing layer 130 away from the hole transport layer 120 and is used to extract photogenerated electrons from the perovskite light-absorbing layer 130. The electron transport buffer layer 150 is located on the side of the electron transport layer 140 away from the perovskite light-absorbing layer 130.

[0119] like Figure 10 As shown, the perovskite light-absorbing layer 130 is configured to absorb photons and generate photogenerated carriers; the electron transport layer 140 is configured to extract photogenerated electrons from the perovskite light-absorbing layer 130; and the electron transport buffer layer 150 is configured to block holes, extract electrons, and play a buffering role in the subsequent electrode formation process to prevent the electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer.

[0120] like Figure 10 As shown, the electron transport buffer layer 150 includes a first sub-buffer layer 151 and a second sub-buffer layer 152. The second sub-buffer layer 152 is located on the side of the first sub-buffer layer 151 away from the electron transport layer 140. The first sub-buffer layer 151 includes a tin oxide film 151, and the second sub-buffer layer 152 includes a first indium tungsten oxide film 190A. That is, the electron transport buffer layer provided in this embodiment includes a tin oxide film and a first indium tungsten oxide film stacked together.

[0121] In the solar cell structure provided in this embodiment, since the electron transport buffer layer includes a first indium tungsten oxide (ITO) thin film, the solar cell structure reduces the fabrication time and cost of the electron transport buffer layer by using ITO as at least a portion of it, thus facilitating the large-scale production of perovskite solar cells. It should be noted that although the electron transport buffer layer also includes a tin oxide (TI) thin film, the thickness of this tin oxide film is reduced, thus requiring less fabrication time, ultimately lowering both the fabrication time and cost. Experiments show that even when the electron transport buffer layer includes a stacked tin oxide thin film and a first ITO thin film, the fabrication time and cost can still be reduced by more than 50%.

[0122] In some examples, the thickness of the second sub-buffer layer 152 is greater than the thickness of the first sub-buffer layer 151. Because the thickness of the first sub-buffer layer is smaller, the manufacturing time and cost are reduced even when using tin oxide.

[0123] In some examples, the thickness of the first sub-buffer layer 151 ranges from 8 to 20 nanometers, and the thickness of the second sub-buffer layer 152 ranges from 30 to 50 nanometers. Thus, although the first sub-buffer layer 151 uses tin oxide, its thickness is significantly reduced, thereby greatly reducing the processing time. On the other hand, due to the greater thickness of the second sub-buffer layer, the hole-blocking capability of the composite electron transport buffer layer is ensured, and it plays a buffering role in the subsequent electrode formation process, effectively resisting the diffusion of copper and iodide ions.

[0124] For example, the thickness of the first sub-buffer layer 151 can be 8 nanometers, 10 nanometers, 16 nanometers and 20 nanometers, and the thickness of the second sub-buffer layer 152 can be 30 nanometers, 40 nanometers and 50 nanometers.

[0125] For example, when the thickness of the first sub-buffer layer 151 is 10 nanometers and the thickness of the second sub-buffer layer 152 is 40 nanometers, the electron transport buffer layer has better buffering performance and lower manufacturing time and cost.

[0126] In the solar cell structure provided in this embodiment, since the second sub-buffer layer is located on the side of the first sub-buffer layer away from the electron transport layer, the first indium tungsten oxide film has a higher density than the tin oxide film. Therefore, it plays a better buffering role in the subsequent electrode formation process. In other words, the first indium tungsten oxide film can better prevent the subsequent electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer. On the other hand, since the electron transport buffer layer includes the first indium tungsten oxide film, this solar cell structure can reduce the adverse effects of the tin oxide precursor on the perovskite light-absorbing layer and the electron transport layer, thereby improving the lifespan and stability of the solar cell structure.

[0127] Furthermore, since the electron transport buffer layer provided in this embodiment includes a stacked tin oxide film and a first indium tungsten oxide film, the tin oxide film, especially the tin oxide film fabricated using atomic deposition, exhibits better organic / inorganic interface matching with the electron transport layer, thereby improving the power conversion efficiency of the solar cell structure. Thus, this solar cell structure utilizes both the better organic / inorganic interface matching between the tin oxide film and the electron transport layer to improve power conversion efficiency, and the higher density of the indium tungsten oxide film to achieve better protection of the electron transport layer and the perovskite light-absorbing layer during the fabrication process. Therefore, this solar cell structure achieves a balance between high power conversion efficiency, long lifespan, and high stability.

[0128] In some examples, the LUMO energy level of the first indium tungsten oxide (ITO) film ranges from -3.2 eV to -3.6 eV, and the HOMO energy level ranges from -7.1 eV to -7.5 eV. Therefore, the LUMO energy level of the ITO film is relatively close to the energy level of the electron transport layer (approximately -4.2 eV), facilitating the extraction and transport of electrons from the electron transport layer. On the other hand, the HOMO energy level of the ITO film, ranging from -7.1 eV to -7.5 eV, is deeper, thus facilitating the blocking of holes. It should be noted that the LUMO and HOMO energy levels of the ITO film can be controlled by adjusting the oxygen content in the process atmosphere during reactive plasma deposition.

[0129] In some examples, the LUMO energy level of the aforementioned tin oxide film is -4.5 eV, resulting in a 0.3 eV difference from the LUMO energy level of the electron transport layer (approximately -4.2 eV), which is more conducive to electron transport. Furthermore, since the electron transport buffer layer provided in this embodiment includes a stacked tin oxide film and a first indium tungsten oxide film, the tin oxide film and the first indium tungsten oxide film can also form a gradient energy level relationship. Therefore, compared to directly using the first indium tungsten oxide film as the electron transport buffer layer, the electron transport buffer layer provided in this example has a better energy level matching relationship, thus enhancing the electron transport capability of the electron transport buffer layer provided in this example. In summary, the electron transport buffer layer provided in this example improves the performance of the electron transport buffer layer from both interface matching and energy level matching perspectives by including a stacked tin oxide film and a first indium tungsten oxide film, thereby enhancing the electron transport capability.

[0130] In some examples, the refractive index of the first indium tungsten oxide film ranges from 2.0 to 2.3, for example, 2.1 or 2.2. Due to the higher density of the indium tungsten oxide film, its refractive index is also relatively higher, increasing from 1.8 for the tin oxide film to 2.1 or 2.2.

[0131] In some examples, the refractive index of the first indium tungsten oxide film is greater than that of the electron transport layer, and the refractive index of the first indium tungsten oxide film is greater than that of the perovskite light-absorbing layer.

[0132] In some examples, the sheet resistance of the first indium tungsten oxide thin film ranges from 1000 Ω / sq to 2000 Ω / sq, exhibiting a relatively low sheet resistance. Therefore, this first indium tungsten oxide thin film not only blocks holes but also facilitates electron transport.

[0133] It should be noted that the materials of the substrate, perovskite light-absorbing layer, hole transport layer, and electron transport layer in the embodiments of this disclosure can be found in [reference needed]. Figure 1 The relevant descriptions of the solar cell structure shown will not be repeated here.

[0134] In some examples, such as Figure 10As shown, the solar cell structure 100 further includes a first electrode layer 160 located on the side of the electron transport buffer layer 150 away from the electron transport layer 140. The first electrode layer 160 includes a first sub-electrode layer 161 and a second sub-electrode layer 162; the second sub-electrode layer 162 is located on the side of the first sub-electrode layer 161 away from the electron transport buffer layer 150. The first sub-electrode layer 161 comprises a transparent conductive oxide, and the second sub-electrode layer 162 comprises a conductive metal. Therefore, the first sub-electrode layer can improve the work function matching between the metal electrode and the electron transport buffer layer, reduce the contact resistance between the metal electrode and the electron transport buffer layer, thereby improving the electron transport efficiency. In addition, the first sub-electrode layer can also prevent the diffusion of metal ions in the metal electrode.

[0135] In some examples, the transparent conductive oxide comprising the first sub-electrode layer described above may be at least one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and indium zinc oxide (IZO). Of course, embodiments of this disclosure include, but are not limited to, indium tungsten oxide (IWO) as well, thereby enabling the simultaneous formation of the electron transport buffer layer and the first sub-electrode layer using the same process, greatly simplifying the process. For further details regarding the use of indium tungsten oxide to form the first sub-electrode layer, please refer to... Figure 13 Related descriptions.

[0136] In some examples, such as Figure 10 As shown, in this solar cell structure 100, the electron transport layer 140 is directly contacted with the perovskite light-absorbing layer 130. Therefore, this solar cell structure does not have a passivation layer between the electron transport layer and the perovskite light-absorbing layer, resulting in a smaller thickness. Furthermore, this solar cell structure avoids the problems of reduced lifespan and stability caused by water absorption by the passivation layer.

[0137] In some examples, such as Figure 10 As shown, the solar cell structure 100 also includes a second electrode layer 180 located between the substrate 110 and the hole transport layer 120.

[0138] For example, the substrate 110 can be made of glass, and the second electrode layer 180 can be made of indium tin oxide or fluorine-doped tin oxide. Of course, embodiments of this disclosure include, but are not limited to, other materials may also be used for the substrate and the second electrode layer.

[0139] Figure 11 This is a schematic diagram of another solar cell structure provided in one embodiment of the present disclosure. Figure 10 The solar cell structure shown is different, Figure 11The solar cell structure 100 shown also includes a passivation layer 170 located between the perovskite light-absorbing layer 130 and the electron transport layer 140. The passivation layer 170 can passivate surface defects of the perovskite light-absorbing layer and effectively increase the open-circuit voltage (Voc), thereby improving the power conversion efficiency (PCE).

[0140] For example, the material of the passivation layer 170 described above can be lithium fluoride (LiF). Of course, embodiments disclosed herein include, but are not limited to, this.

[0141] Figure 12 Comparative graphs of device efficiency and other parameters are shown for several other solar cell structures provided according to embodiments of this disclosure. For example... Figure 12 As shown, Example 3 uses the following... Figure 11 The solar cell structure is shown. In the several sub-examples included in Example 3, the tin oxide film and the first indium tungsten oxide film have different thicknesses, namely SnO2 8nm + IWO 40nm, SnO2 10nm + IWO 40nm, and SnO2 20nm + IWO 40nm, respectively.

[0142] like Figure 12 As shown, since the electron transport buffer layer provided in this embodiment includes a stacked tin oxide thin film and a first indium tungsten oxide thin film, when the thickness of the tin oxide thin film is 10 nanometers and the thickness of the indium tungsten oxide is 40 nanometers, the power conversion efficiency of this solar cell structure can reach 18.54%. It is evident that the solar cell structure provided in this embodiment significantly improves the power conversion efficiency. It should be noted that when the thickness of the tin oxide thin film is 8 nanometers and 20 nanometers, the power conversion efficiencies of this solar cell structure are 17.29% and 18.41%, respectively.

[0143] like Figure 12 As shown, the open-circuit voltage of the solar cell structure first decreases and then increases with the increase of the tin oxide film thickness. When the tin oxide film thickness is 8 nanometers, the open-circuit voltage of the solar cell structure is 1.039V; when the tin oxide film thickness is 10 nanometers, the open-circuit voltage of the solar cell structure is 1.011V; and when the tin oxide film thickness is 20 nanometers, the open-circuit voltage of the solar cell structure is 1.051V.

[0144] like Figure 12 As shown, the fill factor of the solar cell structure first increases and then decreases with the increase of the thickness of the tin oxide film. When the thickness of the tin oxide film is 8 nanometers, the fill factor of the solar cell structure is 67.04%. When the thickness of the tin oxide film is 10 nanometers, the fill factor of the solar cell structure is 77.90%. When the thickness of the tin oxide film is 20 nanometers, the fill factor of the solar cell structure is 75.03%.

[0145] and Figure 10 and Figure 11 Corresponding to the solar cell structure shown, at least one embodiment of this disclosure also provides a method for manufacturing a solar cell structure. The method for manufacturing the solar cell structure includes the following steps S201-S204.

[0146] Step S201: Form a hole transport layer on the substrate.

[0147] For example, a 20-nanometer-thick nickel oxide film can be formed on a substrate using a physical vapor deposition (PVD) process to serve as a hole transport layer.

[0148] For example, the substrate described above can be a glass substrate; the surface of the substrate away from the hole transport layer can serve as the light-incident surface of the solar cell structure.

[0149] Step S202: A perovskite light-absorbing layer is formed on the side of the hole transport layer away from the substrate.

[0150] For example, a perovskite precursor solution can be coated on top of the hole transport layer, and after vacuum-controlled drying (VCD) and hot plate baking (HP) processes, a 500-nanometer perovskite film can be formed as a perovskite light-absorbing layer.

[0151] Step S203: An electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer.

[0152] For example, after the perovskite light-absorbing layer is formed, the electron transport layer is formed directly on the perovskite light-absorbing layer. For example, a 20-nanometer-thick fullerene (C) layer is deposited on the side of the perovskite light-absorbing layer away from the hole transport layer. 60 It serves as an electron transport layer.

[0153] Step S204: A tin oxide film is formed on the side of the electron transport layer away from the perovskite light-absorbing layer to serve as a first sub-buffer layer. Then, a first indium tungsten oxide film is formed on the side of the tin oxide film away from the electron transport layer to serve as a second sub-buffer layer. The first sub-buffer layer and the second sub-buffer layer constitute the electron transport buffer layer. That is, forming the electron transport buffer layer on the side of the electron transport layer away from the perovskite light-absorbing layer includes: forming a tin oxide film on the side of the electron transport layer away from the perovskite light-absorbing layer to serve as a first sub-buffer layer; and forming a first indium tungsten oxide film on the side of the first sub-buffer layer away from the electron transport layer to serve as a second sub-buffer layer.

[0154] For example, the above-mentioned tin oxide thin film can be formed using atomic deposition, and then the above-mentioned first indium tungsten oxide thin film can be formed using reactive plasma deposition.

[0155] In the method for fabricating a solar cell structure provided in this disclosure, a tin oxide thin film is formed on the side of the electron transport layer away from the perovskite light-absorbing layer, and then a first indium tungsten oxide thin film is formed on the side of the tin oxide thin film away from the electron transport layer. Therefore, the final electron transport buffer layer includes the first indium tungsten oxide thin film. Since this solar cell structure uses an indium tungsten oxide thin film as at least a part of the electron transport buffer layer, the fabrication time and cost of the electron transport buffer layer can be reduced, thus facilitating the large-scale production of perovskite solar cells. It should be noted that although the electron transport buffer layer also includes a tin oxide thin film, the thickness of the tin oxide thin film is reduced, thus requiring less fabrication time, ultimately reducing the fabrication time and cost of the electron transport buffer layer. Experiments have shown that even when the electron transport buffer layer includes a stacked tin oxide thin film and a first indium tungsten oxide thin film, the fabrication time of the electron transport buffer layer can still be reduced by more than 50%, and the fabrication cost of the electron transport buffer layer can still be reduced by more than 50%.

[0156] In some examples, the thickness of the second sub-buffer layer is greater than that of the first sub-buffer layer. Because the first sub-buffer layer is thinner, the manufacturing time and cost are reduced even when using tin oxide.

[0157] In some examples, the thickness of the first sub-buffer layer ranges from 8 to 20 nanometers, and the thickness of the second sub-buffer layer ranges from 30 to 50 nanometers. Thus, although the first sub-buffer layer uses tin oxide, its thickness is significantly reduced, thereby greatly reducing the processing time. On the other hand, due to the greater thickness of the second sub-buffer layer, the hole-blocking capability of the composite electron transport buffer layer is ensured, and it plays a buffering role in the subsequent electrode formation process, effectively resisting the diffusion of copper and iodide ions.

[0158] For example, the thickness of the first sub-buffer layer 151 can be 8 nanometers, 10 nanometers, 16 nanometers and 20 nanometers, and the thickness of the second sub-buffer layer 152 can be 30 nanometers, 40 nanometers and 50 nanometers.

[0159] For example, when the thickness of the first sub-buffer layer is 10 nanometers and the thickness of the second sub-buffer layer is 40 nanometers, the electron transport buffer layer has better buffering performance and lower manufacturing time and cost.

[0160] In the method for fabricating a solar cell structure provided in this disclosure, since the second sub-buffer layer is located on the side of the first sub-buffer layer away from the electron transport layer, the first indium tungsten oxide film has higher density than the tin oxide film. Therefore, it plays a better buffering role in the subsequent electrode formation process. In other words, the first indium tungsten oxide film can better prevent the subsequent electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer. On the other hand, since the electron transport buffer layer includes the first indium tungsten oxide film, this solar cell structure can reduce the adverse effects of the tin oxide precursor on the perovskite light-absorbing layer and the electron transport layer, thereby improving the lifespan and stability of the solar cell structure.

[0161] Furthermore, since the electron transport buffer layer provided in this embodiment includes a stacked tin oxide film and a first indium tungsten oxide film, the organic / inorganic interface matching between the tin oxide film, especially the tin oxide film fabricated by atomic deposition process, and the electron transport layer is better, thereby improving the power conversion efficiency of the solar cell structure.

[0162] In some examples, the LUMO energy level of the first indium tungsten oxide (ITO) film ranges from -3.2 eV to -3.6 eV, and the HOMO energy level ranges from -7.1 eV to -7.5 eV. Therefore, the LUMO energy level of the ITO film is relatively close to the energy level of the electron transport layer (approximately -4.2 eV), facilitating the extraction and transport of electrons from the electron transport layer. On the other hand, the HOMO energy level of the ITO film, ranging from -7.1 eV to -7.5 eV, is deeper, thus facilitating the blocking of holes. It should be noted that the LUMO and HOMO energy levels of the ITO film can be controlled by adjusting the oxygen content in the process atmosphere during reactive plasma deposition.

[0163] See Figures 6-9 The parameters of indium tungsten oxide formed under different oxygen contents are shown. When the first indium tungsten oxide thin film is fabricated using reactive plasma deposition, the oxygen content in the process atmosphere can be within the range of 0%-1%, so that the LUMO energy level of the formed first indium tungsten oxide thin film is in the range of -3.28eV to -3.34eV, the HOMO energy level is in the range of -7.14eV to -7.20eV, and it has a high refractive index.

[0164] In some examples, the above-described method for fabricating a solar cell structure further includes forming a first electrode layer on the side of the electron transport buffer layer away from the electron transport layer.

[0165] For example, a sputtering process can be used to form the first electrode layer. This first electrode layer may include a first sub-electrode layer and a second sub-electrode layer; the second sub-electrode layer is located on the side of the first sub-electrode layer away from the electron transport buffer layer. The first sub-electrode layer comprises a transparent conductive oxide, and the second sub-electrode layer comprises a conductive metal. Therefore, the first sub-electrode layer can improve the work function matching between the metal electrode and the electron transport buffer layer, reduce the contact resistance between the metal electrode and the electron transport buffer layer, and thus improve the electron transport efficiency. In addition, the first sub-electrode layer can also prevent the diffusion of metal ions in the metal electrode.

[0166] Thus, the method for fabricating this solar cell structure can be formed. Figure 10 The solar cell structure shown is not limited to this. Of course, embodiments of this disclosure include, but are not limited to, the method for fabricating this solar cell structure, where a perovskite light-absorbing layer can be formed on the side of the hole transport layer away from the substrate, followed by the formation of a passivation layer on the side of the perovskite light-absorbing layer away from the hole transport layer. Thus, the method for fabricating this solar cell structure can form… Figure 11 The solar cell structure shown.

[0167] For example, a 2-nanometer-thick lithium fluoride (LiF) film can be deposited on the surface of the perovskite light-absorbing layer as a passivation layer, and then a 20-nanometer-thick fullerene (C) film can be deposited on the surface of the lithium fluoride (LiF) film. 60 It serves as an electron transport layer.

[0168] At least one embodiment of this disclosure also provides another solar cell structure. Figure 13 This is a schematic diagram of another solar cell structure provided in an embodiment of this disclosure. Figure 13 As shown, the solar cell junction 100 includes a substrate 110, a hole transport layer 120, a perovskite light-absorbing layer 130, an electron transport layer 140, an electron transport buffer layer 150, and a first electrode layer 160. The hole transport layer 120 is located on one side of the substrate 110; the perovskite light-absorbing layer 130 is located on the side of the hole transport layer 120 away from the substrate 110; the electron transport layer 140 is located on the side of the perovskite light-absorbing layer 130 away from the hole transport layer 120, and is used to extract photogenerated electrons from the perovskite light-absorbing layer 130; the electron transport buffer layer 150 is located on the side of the electron transport layer 140 away from the perovskite light-absorbing layer 130; and the first electrode layer 160 is located on the side of the electron transport layer 150 away from the electron transport layer 140.

[0169] like Figure 13As shown, the perovskite light-absorbing layer 130 is configured to absorb photons and generate photogenerated carriers; the electron transport layer 140 is configured to extract photogenerated electrons from the perovskite light-absorbing layer 130; and the electron transport buffer layer 150 is configured to block holes, extract electrons, and play a buffering role in the subsequent electrode formation process to prevent the electrode formation process from adversely affecting the electron transport layer and the perovskite light-absorbing layer.

[0170] like Figure 13 As shown, the electron transport buffer layer 150 includes a first indium tungsten oxide thin film 190A, and the first electrode layer 160 includes a second indium tungsten oxide thin film 190B.

[0171] In the solar cell structure provided in this disclosure, since the electron transport buffer layer includes a first indium tungsten oxide thin film, this solar cell structure, by employing an indium tungsten oxide thin film as at least a portion of the electron transport buffer layer, can reduce the fabrication time and cost of the electron transport buffer, thereby facilitating the large-scale production of perovskite solar cells. Additionally, see the foregoing... Figure 7 and Figure 8 As the oxygen content in the process atmosphere increases, the sheet resistance of the formed indium tungsten oxide thin film gradually decreases, while the conductivity gradually increases. Therefore, in this embodiment, a second indium tungsten oxide thin film is used as the first electrode layer. Thus, this solar cell structure can fabricate both the electron transport buffer layer and the first electrode layer simply by changing process parameters (e.g., the oxygen content in the process atmosphere), thereby greatly expanding equipment capabilities and significantly simplifying the process flow. Furthermore, since both the electron transport buffer layer and the electrode layer are made of indium tungsten oxide, their interface matching is better, further improving power conversion efficiency.

[0172] In some examples, the LUMO energy level of the first indium tungsten oxide (ITO) thin film 190A ranges from -3.2 eV to -3.6 eV, and the HOMO energy level ranges from -7.1 eV to -7.5 eV. Therefore, the LUMO energy level of the first ITO thin film is relatively close to the energy level of the electron transport layer (approximately -4.2 eV), facilitating the extraction and transport of electrons from the electron transport layer. On the other hand, the HOMO energy level of the first ITO thin film, ranging from -7.1 eV to -7.5 eV, is deeper, thus facilitating the blocking of holes. It should be noted that the LUMO and HOMO energy levels of the first ITO thin film can be controlled by adjusting the oxygen content in the process atmosphere during reactive plasma deposition.

[0173] For example, the LUMO energy level of the aforementioned second indium tungsten oxide thin film ranges from -3.59 eV to -3.90 eV, and the HOMO energy level ranges from -7.46 eV to -7.78 eV. See also... Figure 7and Figure 8 According to relevant explanations, when using tungsten oxide and indium oxide as target materials and argon, hydrogen, and oxygen as process atmospheres, the sheet resistance of the formed indium tungsten oxide thin film gradually decreases and the conductivity gradually increases with the increase of oxygen content in the process atmosphere. Therefore, the oxygen content in the process for forming the second indium tungsten oxide thin film is relatively high. See also... Figure 6 According to the relevant explanation, as the oxygen content in the process atmosphere increases, the LUMO energy level and LUMO energy level of the formed indium tungsten oxide gradually shift downward.

[0174] Therefore, in some examples, the LUMO level of the second indium tungsten oxide film 190B is deeper than the LUMO level of the first indium tungsten oxide film 190A, and the HOMO level of the second indium tungsten oxide film 190B is deeper than the HOMO level of the first indium tungsten oxide film 190A. Thus, the first indium tungsten oxide film is more suitable for blocking holes.

[0175] In some examples, the sheet resistance of the second indium tungsten oxide film 190B is lower than that of the first indium tungsten oxide film 190A. Therefore, the second indium tungsten oxide film exhibits better conductivity.

[0176] In some examples, the sheet resistance of the first indium tungsten oxide film ranges from 1000 Ω / sq to 2000 Ω / sq, and the sheet resistance of the second indium tungsten oxide film ranges from 10 Ω / sq to 70 Ω / sq.

[0177] In some examples, the sheet resistance of the second indium tungsten oxide thin film ranges from 10 Ω / sq to 20 Ω / sq, thus exhibiting better conductivity.

[0178] In some examples, the refractive index of the first indium tungsten oxide film ranges from 2.0 to 2.3, for example, 2.1 or 2.2. Due to the higher density of the indium tungsten oxide film, its refractive index is also relatively higher, increasing from 1.8 for the tin oxide film to 2.1 or 2.2.

[0179] In some examples, the oxygen vacancy content of the second indium tungsten oxide film 190B is less than the oxygen vacancy content of the first indium tungsten oxide film 190A.

[0180] In some examples, the refractive index of the first indium tungsten oxide film is greater than that of the second indium tungsten oxide film.

[0181] In some examples, the refractive index of the first indium tungsten oxide film is greater than that of the electron transport layer, and the refractive index of the first indium tungsten oxide film is greater than that of the perovskite light-absorbing layer.

[0182] It should be noted that the materials of the substrate, perovskite light-absorbing layer, hole transport layer, and electron transport layer in the embodiments of this disclosure can be found in [reference needed]. Figure 1The relevant descriptions of the solar cell structure shown will not be repeated here.

[0183] In some examples, such as Figure 13 As shown, the first electrode layer 160 includes a first sub-electrode layer 161 and a second sub-electrode layer 162; the second sub-electrode layer 162 is located on the side of the first sub-electrode layer 161 away from the electron transport buffer layer 150. The first sub-electrode layer 161 includes the aforementioned second indium tungsten oxide thin film 190B, and the second sub-electrode layer 162 includes a conductive metal. Therefore, this first sub-electrode layer can improve the work function matching between the metal electrode and the electron transport buffer layer, reduce the contact resistance between the metal electrode and the electron transport buffer layer, thereby improving the electron transport efficiency. In addition, the first sub-electrode layer can also prevent the diffusion of metal ions in the metal electrode.

[0184] In some examples, such as Figure 13 As shown, in this solar cell structure 100, the electron transport layer 140 is directly contacted with the perovskite light-absorbing layer 130. Therefore, this solar cell structure does not have a passivation layer between the electron transport layer and the perovskite light-absorbing layer, resulting in a smaller thickness. Furthermore, this solar cell structure avoids the problems of reduced lifespan and stability caused by water absorption by the passivation layer.

[0185] In some examples, such as Figure 13 As shown, the solar cell structure 100 also includes a second electrode layer 180 located between the substrate 110 and the hole transport layer 120.

[0186] For example, the substrate 110 can be made of glass, and the second electrode layer 180 can be made of indium tin oxide or fluorine-doped tin oxide. Of course, embodiments of this disclosure include, but are not limited to, other materials may also be used for the substrate and the second electrode layer.

[0187] Figure 14 This is a schematic diagram of another solar cell structure provided in one embodiment of the present disclosure. Figure 13 The solar cell structure shown is different, Figure 14 The solar cell structure 100 shown also includes a passivation layer 170 located between the perovskite light-absorbing layer 130 and the electron transport layer 140. The passivation layer 170 can passivate surface defects of the perovskite light-absorbing layer and effectively increase the open-circuit voltage (Voc), thereby improving the power conversion efficiency (PCE).

[0188] For example, the material of the passivation layer 170 described above can be lithium fluoride (LiF). Of course, embodiments disclosed herein include, but are not limited to, this.

[0189] In some examples, the thickness of the first indium tungsten oxide film ranges from 30 to 50 nanometers, and the thickness of the second indium tungsten oxide film also ranges from 30 to 50 nanometers. Therefore, this solar cell structure can have a high power conversion efficiency. For example, the thicknesses of the first and second indium tungsten oxide films are equal.

[0190] Figure 15 Comparative graphs of device efficiency and other parameters are shown for several other solar cell structures provided according to embodiments of this disclosure. For example... Figure 15 As shown, Example 4 uses the following... Figure 13 The solar cell structure is shown. In Example 4, the thicknesses of the first and second indium tungsten oxide (ITO) films in several sub-examples differ, being 40 nm high-resistivity + 20 nm low-resistivity, 40 nm high-resistivity + 40 nm low-resistivity, and 40 nm high-resistivity + 70 nm low-resistivity, respectively. The "high resistance" refers to the first ITO film with higher sheet resistance, and the "low resistance" refers to the second ITO film with lower sheet resistance.

[0191] like Figure 15 As shown, the power conversion efficiency of the solar cell structure first increases and then decreases with the increase of the thickness of the second indium tungsten oxide film. When the thickness of the second indium tungsten oxide film is 40 nm, the power conversion efficiency of the solar cell structure reaches 18.88%. It is evident that because both the electron transport buffer layer and the electrode layer are made of indium tungsten oxide, their interface matching is better, thus the power conversion efficiency of this solar cell structure can be further improved. It should be noted that when the thickness of the second tin oxide film is 20 nm and 70 nm, the power conversion efficiencies of the solar cell structure are 17.38% and 17.23%, respectively.

[0192] like Figure 15 As shown, the open-circuit voltage of the solar cell structure gradually decreases with the increase of the thickness of the second indium tungsten oxide film. When the thickness of the second tin oxide film is 20 nanometers, the open-circuit voltage of the solar cell structure is 1.024V; when the thickness of the second tin oxide film is 40 nanometers, the open-circuit voltage of the solar cell structure is 1.019V; and when the thickness of the second tin oxide film is 70 nanometers, the open-circuit voltage of the solar cell structure is 1.009V.

[0193] like Figure 15 As shown, the fill factor of the solar cell structure first increases and then decreases with the increase of the thickness of the second indium tungsten oxide film; when the thickness of the second tin oxide film is 20 nanometers, the fill factor of the solar cell structure is 62.15%; when the thickness of the second tin oxide film is 40 nanometers, the fill factor of the solar cell structure is 67.08%; and when the thickness of the second tin oxide film is 70 nanometers, the fill factor of the solar cell structure is 63.30%.

[0194] and Figure 13 and Figure 14 Corresponding to the solar cell structure shown, at least one embodiment of this disclosure also provides a method for manufacturing a solar cell structure. The method for manufacturing the solar cell structure includes the following steps S301-S305.

[0195] Step S301: Form a hole transport layer on the substrate.

[0196] For example, a 20-nanometer-thick nickel oxide film can be formed on a substrate using a physical vapor deposition (PVD) process to serve as a hole transport layer.

[0197] For example, the substrate described above can be a glass substrate; the surface of the substrate away from the hole transport layer can serve as the light-incident surface of the solar cell structure.

[0198] Step S302: A perovskite light-absorbing layer is formed on the side of the hole transport layer away from the substrate.

[0199] For example, a perovskite precursor solution can be coated on top of the hole transport layer, and after vacuum-controlled drying (VCD) and hot plate baking (HP) processes, a 500-nanometer perovskite film can be formed as a perovskite light-absorbing layer.

[0200] Step S303: An electron transport layer is formed on the side of the perovskite light-absorbing layer away from the hole transport layer.

[0201] For example, after the perovskite light-absorbing layer is formed, the electron transport layer is formed directly on the perovskite light-absorbing layer. For example, a 20-nanometer-thick fullerene (C) layer is deposited on the side of the perovskite light-absorbing layer away from the hole transport layer. 60 It serves as an electron transport layer.

[0202] Step S304: A first tin oxide film is formed on the side of the electron transport layer away from the perovskite light-absorbing layer to serve as an electron transport buffer layer.

[0203] Step S305: A second tin oxide film is formed on the side of the electron transport buffer layer away from the electron transport layer, serving as at least a portion of the first electrode layer. That is, forming the first electrode layer on the side of the electron transport buffer layer away from the electron transport layer includes forming a second indium tungsten oxide film on the side of the electron transport buffer layer away from the electron transport layer.

[0204] In the method for fabricating a solar cell structure provided in this disclosure, a first tin oxide thin film is formed on the side of the electron transport layer away from the perovskite light-absorbing layer to serve as an electron transport buffer layer. Therefore, by using an indium tungsten oxide thin film as at least a portion of the electron transport buffer layer, this solar cell structure can reduce the fabrication time and cost of the electron transport buffer layer, thereby facilitating the large-scale production of perovskite solar cells. Additionally, see the foregoing... Figure 7 and Figure 8 As the oxygen content in the process atmosphere increases, the sheet resistance of the formed indium tungsten oxide thin film gradually decreases, while the conductivity gradually increases. Therefore, in this embodiment, a second indium tungsten oxide thin film is used as the first electrode layer. Thus, the fabrication method of this solar cell structure can achieve the fabrication of the electron transport buffer layer and the first electrode layer simply by changing the process parameters, thereby greatly expanding equipment capabilities and significantly simplifying the process flow. Furthermore, since both the electron transport buffer layer and the electrode layer are made of indium tungsten oxide, their interface matching is better, which can further improve the power conversion efficiency.

[0205] In some examples, the fabrication method of the aforementioned solar cell structure further includes forming a conductive metal on the side of the second indium tungsten oxide layer away from the electron transport buffer layer. In this case, the aforementioned second indium tungsten oxide thin film can serve as a first sub-electrode layer, and the conductive metal can serve as a second sub-electrode layer. That is, the first electrode layer includes both a first sub-electrode layer and a second sub-electrode layer. Therefore, the first sub-electrode layer can improve the work function matching between the metal electrode and the electron transport buffer layer, reduce the contact resistance between the metal electrode and the electron transport buffer layer, and thus improve the electron transport efficiency. In addition, the first sub-electrode layer can also prevent the diffusion of metal ions in the metal electrode.

[0206] In some examples, the LUMO energy level of the first indium tungsten oxide (ITO) thin film 190A ranges from -3.2 eV to -3.6 eV, and the HOMO energy level ranges from -7.1 eV to -7.5 eV. Therefore, the LUMO energy level of the first ITO thin film is relatively close to the energy level of the electron transport layer (approximately -4.2 eV), facilitating the extraction and transport of electrons from the electron transport layer. On the other hand, the HOMO energy level of the first ITO thin film, ranging from -7.1 eV to -7.5 eV, is deeper, thus facilitating the blocking of holes. It should be noted that the LUMO and HOMO energy levels of the first ITO thin film can be controlled by adjusting the oxygen content in the process atmosphere during reactive plasma deposition.

[0207] See Figure 7 and Figure 8According to relevant explanations, when using tungsten oxide and indium oxide as target materials and argon, hydrogen, and oxygen as process atmospheres, the sheet resistance of the formed indium tungsten oxide thin film gradually decreases and the conductivity gradually increases with the increase of oxygen content in the process atmosphere. Therefore, the oxygen content in the process for forming the second indium tungsten oxide thin film is relatively high. See also... Figure 6 According to the relevant explanation, as the oxygen content in the process atmosphere increases, the LUMO energy level and LUMO energy level of the formed indium tungsten oxide gradually shift downward.

[0208] Therefore, in some examples, the LUMO level of the second indium tungsten oxide film 190B is deeper than the LUMO level of the first indium tungsten oxide film 190A, and the HOMO level of the second indium tungsten oxide film 190B is deeper than the HOMO level of the first indium tungsten oxide film 190A. Thus, the first indium tungsten oxide film is more suitable for blocking holes.

[0209] In some examples, the sheet resistance of the second indium tungsten oxide film 190B is lower than that of the first indium tungsten oxide film 190A. Therefore, the second indium tungsten oxide film exhibits better conductivity.

[0210] In some examples, the oxygen content in the process atmosphere in which the second indium tungsten oxide film is formed is greater than the oxygen content in the process atmosphere in which the second indium tungsten oxide film is formed.

[0211] See Figures 6-9 The parameters of indium tungsten oxide (ITO) formed under different oxygen contents are shown. When fabricating the first ITO thin film using reactive plasma deposition (RPD), the oxygen content in the process atmosphere can be within the range of 0%-1%, resulting in an ITO thin film with a LUMO energy level ranging from -3.28 eV to -3.34 eV, a HOMO energy level ranging from -7.14 eV to -7.20 eV, and a high refractive index. When fabricating the second ITO thin film using RPD, the oxygen content in the process atmosphere can be within the range of 13%-15%, for example, 14%, resulting in an ITO thin film with a sheet resistance ranging from 10 Ω / sq to 70 Ω / sq.

[0212] For example, the LUMO energy level of the second indium tungsten oxide thin film mentioned above ranges from -3.59 eV to -3.90 eV, and the HOMO energy level ranges from -7.46 eV to -7.78 eV.

[0213] In some examples, the sheet resistance of the first indium tungsten oxide film ranges from 1000 Ω / sq to 2000 Ω / sq, and the sheet resistance of the second indium tungsten oxide film ranges from 10 Ω / sq to 70 Ω / sq.

[0214] In some examples, the sheet resistance of the second indium tungsten oxide thin film ranges from 10 Ω / sq to 20 Ω / sq, thus exhibiting better conductivity.

[0215] In some examples, the refractive index of the first indium tungsten oxide film ranges from 2.0 to 2.3, for example, 2.1 or 2.2. Due to the higher density of the indium tungsten oxide film, its refractive index is also relatively higher, increasing from 1.8 for the tin oxide film to 2.1 or 2.2.

[0216] In some examples, the oxygen vacancy content of the second indium tungsten oxide film 190B is less than the oxygen vacancy content of the first indium tungsten oxide film 190A.

[0217] In some examples, the refractive index of the first indium tungsten oxide film is greater than that of the second indium tungsten oxide film.

[0218] In some examples, the refractive index of the first indium tungsten oxide film is greater than that of the electron transport layer, and the refractive index of the first indium tungsten oxide film is greater than that of the perovskite light-absorbing layer.

[0219] Thus, the method for fabricating this solar cell structure can be formed. Figure 13 The solar cell structure shown is not limited to this. Of course, embodiments of this disclosure include, but are not limited to, the method for fabricating this solar cell structure, where a perovskite light-absorbing layer can be formed on the side of the hole transport layer away from the substrate, followed by the formation of a passivation layer on the side of the perovskite light-absorbing layer away from the hole transport layer. Thus, the method for fabricating this solar cell structure can form… Figure 14 The solar cell structure shown.

[0220] For example, a 2-nanometer-thick lithium fluoride (LiF) film can be deposited on the surface of the perovskite light-absorbing layer as a passivation layer, and then a 20-nanometer-thick fullerene (C) film can be deposited on the surface of the lithium fluoride (LiF) film. 60 It serves as an electron transport layer.

[0221] Figure 16 This is a schematic diagram of another solar cell structure provided in an embodiment of this disclosure. Figure 16 As shown, the solar cell structure 100 uses an indium tungsten oxide thin film as an electron transport buffer layer 150. Figure 1Unlike the solar cell structure shown, the electron transport buffer layer 150 includes a first indium tungsten oxide (ITO) film 190A comprising multiple sub-ITO films 1900 stacked together. In the direction away from the electron transport layer 140, the LUMO energy levels of these sub-ITO films 1900 gradually decrease. Thus, the electron transport buffer layer can form a stepped energy level structure, thereby achieving better electron transport performance. On the other hand, as described above, with the increase of oxygen content in the process atmosphere, the LUMO energy level of the formed indium oxide film gradually decreases. Therefore, the aforementioned multiple sub-ITO films can be formed by controlling the oxygen content, thereby eliminating the need for additional processes.

[0222] In some examples, such as Figure 16 As shown, in the direction away from the electron transport layer 140, the sheet resistance of the multiple sub-indium tungsten oxide films 1900 stacked in the first indium tungsten oxide film 190A gradually decreases. Therefore, this electron transport buffer layer also facilitates electron transport.

[0223] It should be noted that, Figure 16 The solar cell structure shown focuses on improvements to the first indium tungsten oxide thin film. Other film layers in this solar cell structure can be found in other embodiments, or... Figure 16 The provided first indium tungsten oxide thin film can replace the first indium tungsten oxide thin film in other embodiments. An embodiment of this disclosure also provides a solar cell. Figure 17 This is a schematic diagram of the structure of a solar cell provided in one embodiment of this disclosure. Figure 17 As shown, the solar cell 300 includes the aforementioned solar cell structure 100. Therefore, the solar cell possesses the beneficial technical effects corresponding to the technical effects of its included solar cell structure. For example, the solar cell can reduce manufacturing time and costs, thereby facilitating mass production; furthermore, the solar cell also has a long service life and stability.

[0224] In some examples, such as Figure 17 As shown, the solar cell 300 includes multiple solar cell structures 100.

[0225] In some examples, such as Figure 17 As shown, the solar cell 300 also includes a third electrode layer 185, which is disposed in the same layer as the second electrode layer 180, and the first electrode layer 160 is electrically connected to the third electrode layer 185 through a via.

[0226] The following points need to be explained:

[0227] (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure, and other structures can be referred to the general design.

[0228] (2) Where there is no conflict, features of the same embodiment and different embodiments of this disclosure may be combined with each other.

[0229] The above description is merely an exemplary embodiment of this disclosure and is not intended to limit the scope of protection of this disclosure, which is determined by the appended claims.

Claims

1. A solar cell structure, characterized in that, include: Hole transport layer; A perovskite light-absorbing layer is located on one side of the hole transport layer; An electron transport layer is located on the side of the perovskite light-absorbing layer away from the hole transport layer; as well as An electron transport buffer layer is located on the side of the electron transport layer away from the perovskite light-absorbing layer; The electron transport buffer layer includes a first indium tungsten oxide thin film.

2. The solar cell structure according to claim 1, characterized in that, The LUMO energy level of the first indium tungsten oxide thin film ranges from -3.2 eV to -3.6 eV, and the HOMO energy level of the first indium tungsten oxide thin film ranges from -7.1 eV to -7.5 eV.

3. The solar cell structure according to claim 1, characterized in that, The electron transport buffer layer includes a first sub-buffer layer and a second sub-buffer layer, wherein the second sub-buffer layer is located on the side of the first sub-buffer layer away from the electron transport layer. The first sub-buffer layer comprises a tin oxide film, and the second sub-buffer layer comprises the first indium tungsten oxide film.

4. The solar cell structure according to claim 3, characterized in that, The thickness of the second sub-buffer layer is greater than the thickness of the first sub-buffer layer.

5. The solar cell structure according to claim 4, characterized in that, The thickness of the first sub-buffer layer ranges from 8 to 20 nanometers, and the thickness of the second sub-buffer layer ranges from 30 to 50 nanometers.

6. The solar cell structure according to any one of claims 1-5, characterized in that, The sheet resistance of the first indium tungsten oxide thin film ranges from 1000Ω / sq to 2000Ω / sq.

7. The solar cell structure according to any one of claims 1-5, characterized in that, The refractive index of the first indium tungsten oxide thin film ranges from 2.0 to 2.

3.

8. The solar cell structure according to any one of claims 1-5, characterized in that, The refractive index of the first indium tungsten oxide thin film is greater than that of the electron transport layer and the perovskite light-absorbing layer.

9. The solar cell structure according to any one of claims 1-5, characterized in that, The first indium tungsten oxide thin film includes a plurality of sub-indium tungsten oxide thin films stacked together, and the LUMO energy levels of the plurality of sub-indium tungsten oxide thin films gradually decrease in the direction away from the electron transport layer.

10. The solar cell structure according to any one of claims 1-5, characterized in that, Also includes: The first electrode layer is located on the side of the electron transport buffer layer away from the electron transport layer.

11. The solar cell structure according to claim 10, characterized in that, The first electrode layer includes a second indium tungsten oxide thin film.

12. The solar cell structure according to claim 11, characterized in that, The thickness of the first indium tungsten oxide film ranges from 30 to 50 nanometers, and the thickness of the second indium tungsten oxide film ranges from 30 to 50 nanometers.

13. The solar cell structure according to claim 11, characterized in that, The oxygen vacancy content in the second indium tungsten oxide film is less than that in the first indium tungsten oxide film.

14. The solar cell structure according to claim 11, characterized in that, The LUMO level of the second indium tungsten oxide film is deeper than the LUMO level of the first indium tungsten oxide film, and the HOMO level of the second indium tungsten oxide film is deeper than the HOMO level of the first indium tungsten oxide film.

15. The solar cell structure according to claim 11, characterized in that, The sheet resistance of the second indium tungsten oxide film is less than that of the first indium tungsten oxide film.

16. The solar cell structure according to claim 11, characterized in that, The first electrode layer includes a first sub-electrode layer and a second sub-electrode layer. The second sub-electrode layer is located on the side of the first sub-electrode layer away from the electron transport buffer layer. The first sub-electrode layer includes a second indium tungsten oxide thin film, and the second sub-electrode layer includes a conductive metal.

17. The solar cell structure according to claim 10, characterized in that, The first electrode layer includes a first sub-electrode layer and a second sub-electrode layer. The second sub-electrode layer is located on the side of the first sub-electrode layer away from the electron transport buffer layer. The first sub-electrode layer includes indium tin oxide or fluorine-doped tin oxide, and the second sub-electrode layer includes a conductive metal.

18. The solar cell structure according to any one of claims 1-5, characterized in that, The perovskite light-absorbing layer is disposed in contact with the electron transport layer.

19. The solar cell structure according to any one of claims 1-5, characterized in that, Also includes: A passivation layer is located between the perovskite light-absorbing layer and the electron transport layer.

20. The solar cell structure according to any one of claims 1-5, characterized in that, Also includes: The second electrode layer is located on the side of the hole transport layer away from the perovskite light-absorbing layer.

21. The solar cell structure according to any one of claims 1-5, characterized in that, The first indium tungsten oxide thin film in the electron transport buffer layer is fabricated using a reactive plasma deposition process.

22. A solar cell, characterized in that, Includes the solar cell structure according to any one of claims 1-21.

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