Electronic transport layer, preparation method thereof, solar cell and photovoltaic module

Abstract

This application relates to the field of photovoltaic cell technology, and in particular to an electron transport layer and its preparation method, solar cells, and photovoltaic modules. The electron transport layer includes: a fullerene layer comprising a fullerene material; and a sulfur-doped tin oxide layer disposed on the surface of the fullerene layer, the sulfur-doped tin oxide layer comprising a sulfur-doped tin oxide material, wherein sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material. The electron transport layer provided in this application, by disposing a sulfur-doped tin oxide layer on the surface of the fullerene layer, utilizes the anchoring effect of sulfur atoms in the sulfur-doped tin oxide material on the fullerene material. On the one hand, this improves the interfacial bonding force between the fullerene layer and the sulfur-doped tin oxide layer, suppresses the aggregation of components within the fullerene layer, improves the film quality of the fullerene layer and the sulfur-doped tin oxide layer, and thus improves the long-term stability of the solar cell; on the other hand, it improves the charge transport capability between the film layers, thereby improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell technology, and in particular to electron transport layers and their preparation methods, solar cells, and photovoltaic modules. Background Technology

[0002] Perovskite solar cells have attracted widespread attention due to their numerous advantages, including long carrier diffusion length, high absorption coefficient, tunable bandgap, compatibility with various fabrication methods, and simple fabrication process. Currently, in inverted perovskite solar cells, the commonly used electron transport layer is a combination of a fullerene layer and a tin dioxide layer.

[0003] In traditional techniques, fullerene layers are prepared over large areas using vapor deposition, while tin dioxide layers are prepared using atomic layer deposition.

[0004] However, fullerene layers prepared by thermal evaporation often exhibit a relatively loose structure, and tin dioxide layers prepared using traditional methods with the introduction of tin and oxygen sources suffer from numerous film-forming defects, resulting in insufficient film quality and directly reducing the interfacial adhesion between the fullerene and tin dioxide layers. Furthermore, fullerenes spontaneously aggregate during both the evaporation process and the aging process of perovskite solar cells, disrupting film continuity and further reducing interfacial adhesion, thus affecting the long-term stability of the device. Simultaneously, the aggregation of fullerenes and the decrease in interfacial adhesion lead to a reduction in charge transport capacity between film layers, thereby lowering the photoelectric conversion efficiency of the solar cell. Summary of the Invention

[0005] Based on this, it is necessary to provide an electron transport layer and its preparation method, as well as a solar cell and a photovoltaic module. On the one hand, it can improve the interfacial bonding force between the fullerene layer and the sulfur-doped tin oxide layer, suppress the aggregation of components within the fullerene layer, improve the film quality of the fullerene layer and the sulfur-doped tin oxide layer, and thus improve the long-term stability of the solar cell. On the other hand, it can improve the charge transport capability between film layers, thereby improving the photoelectric conversion efficiency of the solar cell.

[0006] A first aspect of this application provides an electron transport layer comprising: a fullerene layer including a fullerene material; and a sulfur-doped tin oxide layer disposed on the surface of the fullerene layer, the sulfur-doped tin oxide layer including a sulfur-doped tin oxide material, wherein sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material.

[0007] In some embodiments, the thickness of the sulfur-doped tin oxide layer is 1 nm to 25 nm.

[0008] In some embodiments, the sulfur-doped tin oxide layer has an amorphous structure.

[0009] In some embodiments, the thickness of the fullerene layer is 5 nm to 30 nm.

[0010] In some embodiments, the components of the fullerene layer are selected from C 60 [6,6]-phenyl-C 61 methyl butyrate, [6,6]-phenyl-C 60 -Methyl butyrate, C 70 and [6,6]-phenyl-C 71 At least one of methyl butyrate.

[0011] The second aspect of this application provides a method for preparing an electron transport layer, the method comprising the following steps: preparing a fullerene layer containing a fullerene material; preparing a sulfur-doped tin oxide layer containing a sulfur-doped tin oxide material by atomic layer deposition, wherein the precursor of the atomic layer deposition includes a tin source and a sulfur-oxygen source, the sulfur-oxygen source including hydrogen sulfide and water vapor; wherein the sulfur-doped tin oxide layer is disposed adjacent to the fullerene layer, and the sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material.

[0012] In some embodiments, the sulfur oxygen source is prepared by vaporization of an aqueous hydrogen sulfide solution.

[0013] In some embodiments, the concentration of the hydrogen sulfide aqueous solution is 10 mg / L to 300 mg / L.

[0014] In some embodiments, the preparation method includes the following steps: S1, preparing a fullerene layer on the surface of a substrate; S2, preparing a sulfur-doped tin oxide layer on the surface of the fullerene layer.

[0015] In some embodiments, step S2 specifically includes the following steps: S21, introducing a sulfur-oxygen source; S22, purging with an inert gas as the purging gas; S23, introducing a tin source; S24, purging with an inert gas as the purging gas; step S21 to step S24 constitute one cycle, and multiple cycles are repeated to form a sulfur-doped tin oxide layer on the surface of the fullerene layer.

[0016] A third aspect of this application provides a solar cell comprising the electron transport layer provided in the first aspect above, or an electron transport layer prepared by the method for preparing the electron transport layer provided in the second aspect above.

[0017] A fourth aspect of this application provides a photovoltaic module comprising the solar cell provided in the third aspect above.

[0018] Compared with traditional technologies, this application has at least the following beneficial effects: The electron transport layer provided in this application, by setting a sulfur-doped tin oxide layer on the surface of the fullerene layer, on the one hand, the overall π delocalized orbitals of the fullerene material in the fullerene layer will affect the sp orbitals of carbon atoms.2 Hybrid orbitals cause atomic orbitals to deflect inwards, towards the interior of the molecule, and outwards towards a positive charge. This attracts the lone pairs of electrons from sulfur atoms in the sulfur-doped tin oxide layer to approach the hybrid orbitals of carbon atoms. The interaction distance is smaller than the van der Waals radius, forming a strong interaction. This anchors the sulfur atoms in the sulfur-doped tin oxide material to the fullerene material, improving the interfacial bonding between the fullerene layer and the sulfur-doped tin oxide layer, suppressing the aggregation of components within the fullerene layer, improving the film quality of both the fullerene layer and the sulfur-doped tin oxide layer, and thus improving the long-term stability of the solar cell. On the other hand, based on the improved interfacial bonding between the fullerene layer and the sulfur-doped tin oxide layer, because the fullerene layer and the sulfur-doped tin oxide layer are anchored through non-covalent interactions, they have similar conduction band edges at the interface, thereby reducing the interlayer band shift and effectively improving the charge transport capability between the film layers, thus improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0019] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0020] Figure 1 This is a schematic diagram of the structure of the electronic transport layer in one embodiment of this application.

[0021] Figure 2 This is a SEM image of the surface of the sulfur-doped tin oxide layer in Example 1 of this application.

[0022] Figure 3 This is a SEM image of the tin oxide layer surface in Comparative Example 1 of this application.

[0023] Figure Labels

[0024] 1. Electron transport layer; 10. Fullerene layer; 20. Sulfur-doped tin oxide layer. Detailed Implementation

[0025] Reference will now be made to detailed embodiments of this application, one or more of which are described below. Each example is provided for explanation and not for limitation of this application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0026] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0027] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0028] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0030] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0031] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0032] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0033] like Figure 1As shown, a first aspect of this application provides an electron transport layer 1, which includes a fullerene layer 10 and a sulfur-doped tin oxide layer 20. The fullerene layer 10 includes a fullerene material. The sulfur-doped tin oxide layer 20 is disposed on the surface of the fullerene layer 10, and the sulfur-doped tin oxide layer 20 includes a sulfur-doped tin oxide material, wherein sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material.

[0034] The electron transport layer 1 provided in this application, by setting a sulfur-doped tin oxide layer 20 on the surface of the fullerene layer 10, allows the overall delocalized Π orbitals of the fullerene material in the fullerene layer 10 to affect the sp orbitals of carbon atoms. 2 Hybrid orbitals cause the atomic orbitals to deflect inwards, towards the interior of the molecule, and outwards towards a positive charge. This attracts the lone pairs of electrons from sulfur atoms in the sulfur-doped tin oxide layer 20 to approach the hybrid orbitals of carbon atoms. The interaction distance is smaller than the van der Waals radius, forming a strong interaction. This anchors the sulfur atoms in the sulfur-doped tin oxide material to the fullerene material, improving the interfacial bonding between the fullerene layer 10 and the sulfur-doped tin oxide layer 20, suppressing the aggregation of components within the fullerene layer 10, and improving the film quality of both the fullerene layer 10 and the sulfur-doped tin oxide layer 20, thereby improving the long-term stability of the solar cell. On the other hand, based on the improved interfacial bonding between the fullerene layer 10 and the sulfur-doped tin oxide layer 20, since the fullerene layer 10 and the sulfur-doped tin oxide layer 20 are anchored through non-covalent interactions, they have similar conduction band edges at the interface, thereby reducing the interlayer band shift and effectively improving the charge transport capability between the film layers, thus improving the photoelectric conversion efficiency of the solar cell.

[0035] Understandably, the sulfur-doped tin oxide layer 20 not only has electron transport capabilities but also provides a good buffer against damage generated during subsequent film preparation, effectively protecting the fullerene layer 10 and the perovskite layer. For example, when preparing films using methods such as magnetron sputtering, the high energy of these methods can damage previously prepared films. However, the sulfur-doped tin oxide layer 20, due to its good coverage and high density, can effectively form a buffer and prevent damage.

[0036] In some embodiments, the thickness of the sulfur-doped tin oxide layer 20 is 1 nm to 25 nm. Exemplarily, the thickness of the sulfur-doped tin oxide layer 20 can be, but is not limited to, 1 nm, 3 nm, 5 nm, 7 nm, 10 nm, 13 nm, 15 nm, 17 nm, 20 nm, 23 nm, and 25 nm. Further, the thickness of the sulfur-doped tin oxide layer 20 is 10 nm to 20 nm. Controlling the thickness of the sulfur-doped tin oxide layer 20 within the above range provides good buffering while enabling rapid carrier transport, reducing the probability of carrier recombination, and improving the photoelectric conversion efficiency of the device.

[0037] In some embodiments, the sulfur-doped tin oxide layer 20 has an amorphous structure. Thus, due to its amorphous structure, the sulfur-doped tin oxide layer 20 exhibits good film-forming properties, covering the surface of the fullerene layer 10, further improving the interfacial stability between the fullerene layer 10 and the sulfur-doped tin oxide layer 20, thereby enhancing the stability of the device.

[0038] In some embodiments, the thickness of the fullerene layer 10 is 5 nm to 30 nm. Exemplarily, the thickness of the fullerene layer 10 can be, but is not limited to, 5 nm, 7 nm, 10 nm, 13 nm, 15 nm, 17 nm, 20 nm, 23 nm, 25 nm, 27 nm, and 30 nm.

[0039] In some embodiments, the composition of the fullerene layer 10 is selected from C 60 [6,6]-phenyl-C 61 methyl butyrate, [6,6]-phenyl-C 60 -Methyl butyrate, C 70 and [6,6]-phenyl-C 71 At least one of methyl butyrate.

[0040] The second aspect of this application provides a method for preparing an electron transport layer, the method comprising the following steps: preparing a fullerene layer containing a fullerene material.

[0041] A sulfur-doped tin oxide layer containing sulfur-doped tin oxide material was prepared by atomic layer deposition. The precursors for atomic layer deposition included a tin source and a sulfur-oxygen source, and the sulfur-oxygen source included hydrogen sulfide and water vapor.

[0042] The sulfur-doped tin oxide layer and the fullerene layer are arranged adjacent to each other, and the sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material.

[0043] The electron transport layer preparation method provided in this application improves the interfacial adhesion and electron transport performance of the film by introducing tin and sulfur-oxygen sources as precursors for atomic layer deposition (ALD) to prepare a sulfur-doped tin oxide layer. Specifically, hydrogen sulfide and water vapor are introduced as sulfur-oxygen sources. The presence of water vapor ionizes the hydrogen sulfide, allowing the sulfur-oxygen source and tin source to undergo alternating adsorption reactions during ALD treatment, uniformly depositing a sulfur-doped tin oxide layer containing sulfur-doped tin oxide material. Compared with tin oxide layers in traditional techniques, the sulfur-doped tin oxide layer exhibits better electron transport performance and stronger interfacial affinity. The global π-delocalized orbitals of the fullerene material in the fullerene layer affect the sp orbitals of carbon atoms. 2Hybrid orbitals cause atomic orbitals to deflect inwards, towards the interior of the molecule, and outwards towards a positive charge. This attracts the lone pairs of electrons from sulfur atoms in the sulfur-doped tin oxide layer to approach the hybrid orbitals of carbon atoms. The interaction distance is smaller than the van der Waals radius, forming a strong interaction. This allows sulfur atoms in the sulfur-doped tin oxide material to anchor to the fullerene material, enhancing interfacial bonding, suppressing carrier recombination, and improving device stability and lifetime. At the same time, at the interface between the fullerene layer and the sulfur-doped tin oxide layer, both have similar conduction band edges, thereby reducing interlayer band shift and effectively improving the charge transport capability between film layers.

[0044] It is understood that this application does not restrict the order of preparation of the fullerene layer and the sulfur-doped tin oxide layer, as long as the anchoring effect of the fullerene layer and the sulfur-doped tin oxide layer can be achieved.

[0045] In some embodiments, the sulfur-oxygen source is prepared by vaporization of an aqueous hydrogen sulfide solution. This method of preparing the sulfur-oxygen source has two advantages: firstly, the aqueous and gaseous phases maintain a dynamic equilibrium during vaporization, enabling the synchronous and uniform release of hydrogen sulfide and water vapor. This avoids ratio fluctuations and localized concentration unevenness caused by external mixing, improving the consistency of the reaction and the uniformity of the film composition during deposition; secondly, it avoids the safety risks associated with directly introducing high concentrations of hydrogen sulfide gas, resulting in more stable system operation and facilitating industrial-scale operation.

[0046] In some embodiments, the concentration of the hydrogen sulfide aqueous solution is from 10 mg / L to 300 mg / L. Exemplarily, the concentration of the hydrogen sulfide aqueous solution can be, but is not limited to, 10 mg / L, 30 mg / L, 50 mg / L, 60 mg / L, 80 mg / L, 100 mg / L, 120 mg / L, 140 mg / L, 160 mg / L, 180 mg / L, 200 mg / L, 220 mg / L, 240 mg / L, 260 mg / L, 280 mg / L, and 300 mg / L. Thus, by adjusting the concentration of the hydrogen sulfide aqueous solution, the relative ratio of hydrogen sulfide to water vapor in the sulfur-oxygen source is adjusted, thereby controlling the sulfur doping amount. This allows for effective chemical bonding and effective adjustment of the bandgap width of the sulfur-doped tin oxide layer 20, thereby improving the long-term stability and photoelectric conversion efficiency of the device.

[0047] In some embodiments, the aqueous hydrogen sulfide solution contains sodium hydroxide. Thus, the presence of sodium hydroxide adjusts the pH of the aqueous hydrogen sulfide solution. Under alkaline conditions (pH > 9), H₂S is converted to HS₂. - or S 2- The apparent solubility is greatly increased, which improves the solubility of hydrogen sulfide in water and ensures a stable supply of sulfur and oxygen sources in the ALD process.

[0048] In some specific embodiments, the concentration of sodium hydroxide in the aqueous hydrogen sulfide solution is 0 wt%-0.05 wt%. Exemplarily, the concentration of sodium hydroxide in the aqueous hydrogen sulfide solution can be, but is not limited to, 0 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, or 0.05 wt%. By controlling the concentration within a suitable range, sodium hydroxide can provide an alkaline environment in the aqueous hydrogen sulfide solution without adversely affecting the overall reaction (e.g., reacting with H₂S) due to excessive concentration.

[0049] In some embodiments, the preparation of a fullerene layer containing fullerene material specifically includes the following steps: S11, using a vapor deposition apparatus, adding the components of the fullerene layer to the apparatus crucible, placing the substrate into the vapor deposition apparatus, and evacuating to a vacuum of 2×10⁻⁶. -4 Pa and below.

[0050] S12. After preheating, open the main baffle of the vapor deposition equipment, rotate the substrate, and deposit a fullerene layer on the surface of the substrate.

[0051] S13. After deposition is complete, close the main baffle of the vapor deposition equipment, stop rotating the substrate, and cool it before removing it.

[0052] In some embodiments, the tin source includes at least one of the following compounds: organotin compounds such as tetra(dimethylamino)tin (TDMASn), tetramethyltin (TMT), and tetraethyltin (TET); tin halides such as tin tetrachloride (SnCl4) and tin tetraiodide (SnI4); alkylaminotin compounds such as bis(diethylamino)ditin (Sn(Net2)2) and tris(dimethylamino)methyltin (SnMe(NMe2)3); and oxygen-containing tin precursors such as tin tert-butoxide (Sn(OtBu)4) and tin acetate (Sn(OOCCH3)4).

[0053] In some embodiments, the atomic layer deposition process is performed at a temperature of 50°C to 150°C. Exemplarily, the atomic layer deposition process temperature can be, but is not limited to, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C.

[0054] It is understandable that the above temperature range refers to the low-temperature range. Sulfur-doped tin oxide layers formed by ALD treatment at low temperatures typically exhibit an amorphous structure. Amorphous structures are more dense at the nanoscale, lacking grain boundaries and dislocations, effectively avoiding stress concentration and grain boundary carrier trapping problems common in crystalline structures, thus improving film quality. Simultaneously, the good structural continuity and high surface smoothness of amorphous sulfur-doped tin oxide layers facilitate close adhesion with fullerene layers, reducing carrier recombination probability and further improving electron transport efficiency and long-term device stability.

[0055] In some embodiments, the preparation method includes the following steps: S1, preparing a fullerene layer on the surface of a substrate.

[0056] S2. Prepare a sulfur-doped tin oxide layer on the surface of the fullerene layer.

[0057] In this article, "substrate" refers to a process precursor used to construct the front-end device structure before building the electron transport layer. For example, in an inverted perovskite solar cell structure, the substrate may include a multilayer structure consisting of a substrate, a hole transport layer, and a perovskite light-absorbing layer formed sequentially.

[0058] In some embodiments, step S2 specifically includes the following steps: S21, introducing a sulfur-oxygen source.

[0059] S22. Purging is performed using an inert gas as the purging gas.

[0060] S23, Introduce tin source.

[0061] S24. Purging is performed using inert gas as the purging gas.

[0062] Steps S21 to S24 constitute one cycle, and multiple cycles are repeated to form a sulfur-doped tin oxide layer on the surface of the fullerene layer.

[0063] Thus, in the ALD process, a sulfur-oxygen source is first introduced, where hydrogen sulfide preferentially adsorbs onto the fullerene layer surface, achieving initial anchoring. Subsequently, a tin source is introduced, where the tin precursor reacts with the adsorbed sulfur atoms and water vapor to form a sulfur-doped tin oxide layer. This reaction sequence helps to improve the anchoring effect of sulfur atoms, enhances the bonding force between the sulfur-doped tin oxide layer and the fullerene layer, and improves the film's density and interfacial stability.

[0064] It is understood that this application does not limit the order in which the sulfur-oxygen source and the tin source are introduced. Because in the early stages of atomic layer deposition, film growth follows an island-like nucleation mechanism, the precursor preferentially forms nanoclusters at local adsorption sites, which then connect and grow into a continuous film. Therefore, even if the tin source is introduced first, followed by the sulfur-oxygen source, the technical solution of this application can still be achieved. Specifically, if the tin source is introduced first, it can initially adsorb onto the fullerene layer surface to form reaction sites. In the subsequent sulfur-oxygen source introduction stage, hydrogen sulfide and water vapor react with tin atoms to generate sulfur-doped tin oxide, which, within the electronic environment of the conjugated carbon skeleton of the fullerene material, further induces sulfur atoms to anchor to the fullerene material, achieving stable interfacial bonding.

[0065] In some embodiments, in step S21 or S23, an inert gas is introduced as a carrier gas into the sulfur-oxygen source or tin source, and the flow rate of the carrier gas is 100 sccm to 1000 sccm. Exemplarily, the flow rate of the carrier gas can be, but is not limited to, 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm.

[0066] In some embodiments, in step S21, the introduction time of the sulfur-oxygen source is 50 ms to 500 ms. Exemplarily, the introduction time of the sulfur-oxygen source can be, but is not limited to, 50 ms, 100 ms, 150 ms, 200 ms, 250 ms, 300 ms, 350 ms, 400 ms, 450 ms, and 500 ms.

[0067] In some embodiments, in step S23, the tin source is introduced for a time of 50 ms to 500 ms. For example, the tin source introduction time can be, but is not limited to, 50 ms, 100 ms, 150 ms, 200 ms, 250 ms, 300 ms, 350 ms, 400 ms, 450 ms, or 500 ms.

[0068] In some embodiments, in step S22 or step S24, the flow rate of the purge gas is 100 sccm to 1000 sccm. Exemplarily, the flow rate of the purge gas can be, but is not limited to, 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, 900 sccm, or 1000 sccm.

[0069] In some embodiments, the purging time of the purge gas in step S22 or step S24 is 5 s to 60 s. Exemplarily, the purging time of the purge gas can be, but is not limited to, 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, or 60 s.

[0070] In some embodiments, the number of cycles is from 10 to 250. Exemplarily, the number of cycles can be, but is not limited to, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 230, or 250. Thus, by controlling the number of cycles, the thickness of the sulfur-doped tin oxide layer is controlled.

[0071] In some of these embodiments, the inert gas includes nitrogen or argon.

[0072] In other embodiments, the preparation method includes the following steps: S3, preparing a sulfur-doped tin oxide layer on the surface of a substrate.

[0073] S4. Prepare a fullerene layer on the surface of the sulfur-doped tin oxide layer.

[0074] A third aspect of this application provides a solar cell comprising the electron transport layer provided in the first aspect above, or an electron transport layer prepared by the method for preparing the electron transport layer provided in the second aspect above.

[0075] This application does not limit the specific structure of the solar cell; in one specific embodiment, the solar cell includes one of the following: perovskite single-cell cell, perovskite / perovskite tandem cell, perovskite / crystalline silicon tandem cell, perovskite / organic tandem cell, and perovskite / copper indium gallium selenide tandem cell.

[0076] In some of these embodiments, the solar cell is an inverted solar cell.

[0077] Generally speaking, a reverse solar cell consists of a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode layer in that order; that is, incident light passes through the substrate, hole transport layer, perovskite layer, electron transport layer, and electrode layer in sequence.

[0078] In some embodiments, the substrate is selected from crystalline silicon cells, conductive glass, and flexible conductive films.

[0079] In some embodiments, the crystalline silicon solar cell includes one of the following: passivated emitter and back contact cell (PERC cell), tunnel oxide passivated contact cell (TOPCon cell), crystalline silicon heterojunction solar cell (HJT cell), and back contact cell (IBC cell).

[0080] In some embodiments, the conductive glass has a certain degree of transparency. The conductive glass typically consists of a glass substrate and a conductive oxide thin film (TCO) layer. Commonly used TCOs include, but are not limited to, the following materials: fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), and indium zinc oxide (IZO). The conductive glass is generally any conductive glass used in the art. Conductive glass is commercially available. The conductive glass needs to be cleaned before use, for example, by ultrasonic cleaning with a cleaning agent, deionized water, or ethanol.

[0081] In some embodiments, the flexible conductive film includes one of indium tin oxide (ITO) film, fluorine-doped tin oxide (FTO) film, aluminum-doped zinc oxide (AZO) film, boron-doped zinc oxide (BZO) film, and indium zinc oxide (IZO) film.

[0082] In some embodiments, the perovskite has a three-dimensional structure ABX3, where A is a monovalent cation, including one or a mixture of monovalent cations selected from cesium (Cs), rubidium (Rb), methylamino (CH3NH3), and formamidinyl (CH2(NH2)2); B is a divalent cation, including one or a mixture of divalent cations selected from lead (Pb), copper (Cu), zinc (Zn), gallium (Ga), tin (Sn), and calcium (Ca); and X is a monovalent anion, including one or a mixture of monovalent anions selected from iodine (I), bromine (Br), chloride (Cl), fluorine (F), and thiocyanate (SCN). It should be understood that those skilled in the art can make corresponding adjustments to the content of each component in the above compound according to actual needs, and this embodiment does not impose specific limitations in this regard.

[0083] In some embodiments, the hole transport layer comprises one or more of the following materials: [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), benzoic acid, 4-[bis(2,4-dimethoxybiphenyl-4-yl)amino]-biphenyl-4-carboxylic acid [M C-43], Sprio-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene), PTAA (polyethylene terephthalate), P3HT (polymer of 3-hexylthiophene), PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)), Spiro-TTB (2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'-difluorene), NiO x , CuSCN, CuAlO2, V2O5, CdS, CdSe.

[0084] In some embodiments, the electrode material includes one or more of the following materials: Au, Ag, Al, Cu, graphene, TCO material, and nanocrystalline silicon. The electrode preparation method includes one or more of the following: spin coating, blade coating, vapor deposition, printing, spray coating, spray pyrolysis, and slot coating.

[0085] A fourth aspect of this application provides a photovoltaic module comprising the solar cell provided in the third aspect above.

[0086] Furthermore, multiple solar cells can be configured, and these solar cells can be electrically connected in a single unit or in multiple segments to form multiple cell strings. These cell strings can be electrically connected in series and / or parallel. The photovoltaic module may also include an encapsulation layer and a cover plate. The encapsulation layer covers the surface of the cell strings, and the cover plate covers the surface of the encapsulation layer away from the cell strings. Specifically, in some embodiments, multiple cell strings can be electrically connected through conductive means. The encapsulation layer covers the surface of the solar cells. Exemplarily, the encapsulation layer can be an organic encapsulation film such as an ethylene-vinyl acetate copolymer film, a polyethylene octene co-elastomer film, or a polyethylene terephthalate film. The cover plate can be a glass cover plate, a plastic cover plate, or other light-transmitting cover plate.

[0087] The photovoltaic module also possesses the advantages of the solar cells in any of the above embodiments, and will not be repeated here.

[0088] Based on the same inventive concept, this application provides a photovoltaic system including the photovoltaic module in any of the above embodiments. The advantages of the aforementioned photovoltaic module are also possessed by this photovoltaic system, and will not be repeated here.

[0089] It is understandable that photovoltaic (PV) systems can be applied to PV power plants, such as ground-mounted, rooftop, and floating power plants, as well as to equipment or devices that utilize solar energy for power generation, such as user-installed solar power supplies, solar streetlights, solar-powered cars, and solar-powered buildings. Of course, it is also understandable that the application scenarios of PV systems are not limited to these; that is, PV systems can be applied in all areas that require solar energy for power generation. Taking a PV power grid as an example, a PV system can include PV arrays, combiner boxes, and inverters. A PV array can be a combination of multiple PV modules; for example, multiple PV modules can form multiple PV arrays. The PV arrays are connected to combiner boxes, which collect the current generated by the PV arrays. The collected current then flows through an inverter, converting it into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0090] The present application will be further described below with reference to specific embodiments and comparative examples.

[0091] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0092] Example 1

[0093] The electron transport layer was prepared by the following steps (1)-(2).

[0094] (1) Using vapor deposition equipment, add C to the equipment crucible. 60 The substrate is then placed in an evaporation deposition apparatus and evacuated to a vacuum level of 2×10⁻⁶. -4 Pa, after preheating, open the main baffle of the vapor deposition equipment, rotate the substrate, and place C 60 The evaporation rate was controlled at 0.1 A / s, and a 20 nm fullerene layer was deposited on the surface of the substrate. After deposition, the main baffle of the evaporation equipment was turned off, the substrate was stopped from rotating, and cooled and removed.

[0095] (2) The substrate with the fullerene layer deposited on the surface is placed in the chamber for atomic deposition and deposition is started at 100°C and 0.1 torr. One cycle is as follows: first, a sulfur-oxygen source (a mixture of H2S and water vapor) is introduced with N2 as the carrier gas (flow rate 500 scm) for 100 ms; then, N2 is used as the purge gas (flow rate 500 scm) for 60 s; then, a tin source TDMASn is introduced with N2 as the carrier gas (flow rate 500 scm) for 100 ms; finally, N2 is used as the purge gas (flow rate 500 scm) for 60 s; repeat the above cycle 100 times to form a 10 nm sulfur-doped tin oxide layer on the surface of the fullerene layer.

[0096] The sulfur oxygen source is obtained by vaporization treatment of hydrogen sulfide aqueous solution. The concentration of the hydrogen sulfide aqueous solution is 100 mg / L, and the hydrogen sulfide aqueous solution contains 0.01 wt% sodium hydroxide as a co-solvent.

[0097] Figure 2 This is a SEM image of the sulfur-doped tin oxide layer surface in this embodiment. Figure 2 As shown, by anchoring sulfur atoms in the sulfur-doped tin oxide material to the fullerene material, the interfacial bonding force between the fullerene layer and the sulfur-doped tin oxide layer is improved, resulting in a high-quality thin film of the sulfur-doped tin oxide layer.

[0098] Solar cells:

[0099] The solar cell is an inverted perovskite solar cell. The fabrication method for an inverted perovskite solar cell is as follows: First, a hole transport layer (Me-4PACz material) and a perovskite substrate film (FA) are sequentially fabricated on ITO conductive glass. 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 material), as the substrate; use the above-mentioned method for preparing the electron transport layer to prepare the electron transport layer on the substrate; prepare the electrode layer (Ag metal) on the electron transport layer to obtain the inverse perovskite solar cell.

[0100] Example 2

[0101] In this embodiment, the preparation method of the electron transport layer and the solar cell is basically the same as that in Example 1, except that in step (2), the number of cycles is 10, and the thickness of the sulfur-doped tin oxide layer prepared therefrom is 1 nm.

[0102] Example 3

[0103] In this embodiment, the preparation method of the electron transport layer and the solar cell is basically the same as that in Example 1, except that in step (2), the number of cycles is 250, and the thickness of the sulfur-doped tin oxide layer prepared therefrom is 25 nm.

[0104] Example 4

[0105] The preparation methods of the electron transport layer and the solar cell in this embodiment are basically the same as those in Example 1, except that the concentration of the hydrogen sulfide aqueous solution in step (2) is 1 wt%.

[0106] Example 5

[0107] The preparation methods of the electron transport layer and the solar cell in this embodiment are basically the same as those in Example 1, except that the concentration of the hydrogen sulfide aqueous solution in step (2) is 10 wt%.

[0108] Table 1 shows a summary of some important parameters from Examples 1 to 5.

[0109] Table 1

[0110] Thickness (nm) of sulfur-doped tin oxide layer Concentration of hydrogen sulfide aqueous solution (mg / L) Number of loops (times) Example 1 10 100 100 Example 2 1 100 10 Example 3 25 100 250 Example 4 10 10 100 Example 5 10 300 100

[0111] Example 6

[0112] The electron transport layer was prepared by the following steps (1)-(2).

[0113] (1) Using vapor deposition equipment, add C to the equipment crucible. 60 The substrate is then placed in an evaporation deposition apparatus and evacuated to a vacuum level of 2×10⁻⁶. -4 Pa, after preheating, open the main baffle of the vapor deposition equipment, rotate the substrate, and place C 60 The evaporation rate was controlled at 0.1 A / s, and a 20 nm fullerene layer was deposited on the surface of the substrate. After deposition, the main baffle of the evaporation equipment was turned off, the substrate was stopped from rotating, and cooled and removed.

[0114] (2) The substrate with the fullerene layer deposited on the surface is placed in the chamber for atomic deposition and deposition is started at 100°C and 0.1 torr. One cycle is as follows: first, tin source TDMASn is introduced with N2 as carrier gas (flow rate 500 scm); purging is performed with N2 as purge gas (flow rate 500 scm) for 60 s; sulfur-oxygen source (mixed gas of H2S and water vapor) is introduced with N2 as carrier gas (flow rate 500 scm) for 100 ms; finally, purging is performed with N2 as purge gas (flow rate 500 scm) for 60 s; repeat the above cycle 100 times to form a 10 nm sulfur-doped tin oxide layer on the surface of the fullerene layer.

[0115] The sulfur oxygen source is obtained by vaporization treatment of hydrogen sulfide aqueous solution. The concentration of the hydrogen sulfide aqueous solution is 100 mg / L, and the hydrogen sulfide aqueous solution contains 0.01 wt% sodium hydroxide as a co-solvent.

[0116] Solar cells:

[0117] The solar cell is an inverted perovskite solar cell. The fabrication method for an inverted perovskite solar cell is as follows: First, a hole transport layer (Me-4PACz material) and a perovskite substrate film (FA) are sequentially fabricated on ITO conductive glass. 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 material), as the substrate; use the above-mentioned method for preparing the electron transport layer to prepare the electron transport layer on the substrate; prepare the electrode layer (Ag metal) on the electron transport layer to obtain the inverse perovskite solar cell.

[0118] Comparative Example 1

[0119] The electron transport layer was prepared by the following steps (1)-(2).

[0120] (1) Using vapor deposition equipment, add C to the equipment crucible. 60 The substrate is then placed in an evaporation deposition apparatus and evacuated to a vacuum level of 2×10⁻⁶. -4 Pa, after preheating, open the main baffle of the vapor deposition equipment, rotate the substrate, and place C 60 The evaporation rate was controlled at 0.1 A / s, and a 20 nm fullerene layer was deposited on the surface of the substrate. After deposition, the main baffle of the evaporation equipment was turned off, the substrate was stopped from rotating, and cooled and removed.

[0121] (2) The substrate with the fullerene layer deposited on the surface is placed in the chamber for atomic deposition and deposition is started at 100°C and 0.1 torr. One cycle is as follows: first, tin source TDMASn is introduced with N2 as carrier gas (flow rate 500 scm); then, N2 is used as purge gas (flow rate 500 scm) for 60 s; then, oxygen source water vapor is introduced with N2 as carrier gas (flow rate 500 scm) for 500 ms; finally, N2 is used as purge gas (flow rate 500 scm) for 60 s; repeat the above cycle 100 times to form a 10 nm tin oxide layer on the surface of the fullerene layer.

[0122] Figure 3 This is a SEM image of the tin oxide layer surface in this comparative example. Figure 3 As shown, the tin dioxide layer prepared by introducing tin and oxygen sources using traditional methods has many film-forming defects and the film quality is insufficient.

[0123] Solar cells:

[0124] The solar cell is an inverted perovskite solar cell. The fabrication method for an inverted perovskite solar cell is as follows: First, a hole transport layer (Me-4PACz material) and a perovskite substrate film (FA) are sequentially fabricated on ITO conductive glass. 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 material), as the substrate; use the above-mentioned method for preparing the electron transport layer to prepare the electron transport layer on the substrate; prepare the electrode layer (Ag metal) on the electron transport layer to obtain the inverse perovskite solar cell.

[0125] Performance testing

[0126] The solar cells fabricated in the above embodiments and comparative examples were placed in a solar simulator (manufacturer: Wavelabs). Under the illumination of a certain solar intensity, a bias voltage (Vp, bias voltage range of -0.1 to 1.3V) was applied to the device using a test source meter, and the output current of the device was tested to obtain the bias voltage-current density curve.

[0127] Open-circuit voltage (Voc): The terminal voltage of the solar cell when no load is connected, i.e., when the current density in the bias-current density curve is 0 mA·cm. -2 The bias voltage value at that time.

[0128] Short-circuit current density (Jsc): The output current per unit area of ​​the solar cell when it is short-circuited, i.e., the current density when the bias voltage is 0V in the bias voltage-current density curve.

[0129] Fill factor (FF): FF = max(Vp × Jsc), where Vp is the bias voltage and Jsc is the short-circuit current density.

[0130] Photovoltaic cell efficiency (PCE): PCE = Voc × Jsc × FF.

[0131] Aging test: The solar cells prepared in the above examples and comparative examples were heated at 85°C for 1000 hours in air with 85% humidity.

[0132] The test results for the above performance are shown in Table 2.

[0133] Table 2

[0134] Voc(V) <![CDATA[Jsc(mA·cm -2 )]]> FF (%) PCE before aging (%) PCE after aging (%) Example 1 1.17 24.88 80.37 23.39 21.68 Example 2 1.01 17.86 61.11 11.02 1.46 Example 3 1.16 24.41 78.46 22.21 19.96 Example 4 1.16 24.57 79.02 22.51 19.52 Example 5 1.17 24.8 79.85 23.16 21.07 Example 6 1.17 24.45 79.02 22.60 20.03 Comparative Example 1 1.16 24.43 77.87 22.06 19.11

[0135] As shown in Table 2, comparing Examples 1-6 and Comparative Example 1, it can be seen that the electron transport layer provided in this application has excellent interfacial bonding and electron transport capabilities. When applied to solar cells, it improves the photoelectric conversion efficiency and long-term stability of solar cells.

[0136] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An electron transport layer, characterized in that, include: Fullerene layers, including fullerene materials; and A sulfur-doped tin oxide layer is disposed on the surface of the fullerene layer, the sulfur-doped tin oxide layer comprising a sulfur-doped tin oxide material, wherein sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material; The sulfur-doped tin oxide layer has an amorphous structure.

2. The electron transport layer according to claim 1, characterized in that, The thickness of the sulfur-doped tin oxide layer is 1 nm to 25 nm.

3. The electron transport layer according to claim 1 or 2, characterized in that, The fullerene layer satisfies at least one of the following conditions: (1) The thickness of the fullerene layer is 5 nm to 30 nm; (2) In the fullerene layer, the fullerene material is selected from C 60 [6,6]-phenyl-C 61 methyl butyrate, [6,6]-phenyl-C 60 -Methyl butyrate, C 70 and [6,6]-phenyl-C 71 At least one of methyl butyrate.

4. A method for preparing an electron transport layer, characterized in that, Includes the following steps: Prepare a fullerene layer containing a fullerene material; A sulfur-doped tin oxide layer containing sulfur-doped tin oxide material is prepared by atomic layer deposition (ALD). The precursor of the ALD process includes a tin source and a sulfur-oxygen source, wherein the sulfur-oxygen source includes hydrogen sulfide and water vapor. The sulfur-doped tin oxide layer is disposed adjacent to the fullerene layer, and the sulfur atoms in the sulfur-doped tin oxide material are anchored to the fullerene material.

5. The method for preparing the electron transport layer according to claim 4, characterized in that, The sulfur-oxygen source is prepared by vaporization of hydrogen sulfide aqueous solution.

6. The method for preparing an electron transport layer according to claim 5, characterized in that, The concentration of the hydrogen sulfide aqueous solution is 10 mg / L to 300 mg / L.

7. The method for preparing an electron transport layer according to any one of claims 4 to 6, characterized in that, Includes the following steps: S1. Prepare the fullerene layer on the surface of the substrate; S2. Prepare the sulfur-doped tin oxide layer on the surface of the fullerene layer.

8. The method for preparing an electron transport layer according to claim 7, characterized in that, Step S2 specifically includes the following steps: S21, Introduce a sulfur-oxygen source; S22. Purging is performed using inert gas as the purging gas; S23, Introduce tin source; S24. Purging is performed using inert gas as the purging gas; The process involves repeating steps S21 to S24 as one cycle, and then repeating multiple cycles to form the sulfur-doped tin oxide layer on the surface of the fullerene layer.

9. A solar cell, characterized in that, It includes the electron transport layer as described in any one of claims 1 to 3, or the electron transport layer prepared by the method described in any one of claims 4 to 8.

10. A photovoltaic module, characterized in that, Including the solar cell as described in claim 9.

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