Perovskite solar cell, preparation method thereof and photovoltaic system

Abstract

The embodiment of the invention provides a perovskite solar cell, a preparation method thereof and a photovoltaic system. The preparation method of the perovskite solar cell comprises the following steps: providing a substrate; forming a first transmission layer on one side of the substrate; depositing chloride on one side, far away from the substrate, of the first transmission layer to form a pretreatment layer; forming an intermediate layer on one side of the pretreatment layer, and performing annealing treatment to form a perovskite layer; and sequentially forming a second transmission layer and an electrode on one side, far away from the first transmission layer, of the perovskite layer. According to the technical scheme of the embodiment of the invention, the pretreatment layer in contact with the bottom interface of the middle layer is formed by evaporating the chloride, so that residual lead iodide on the bottom interface can be reduced, a thin film with good crystallization and high uniformity is formed, and the light stability and the photoelectric conversion efficiency of the cell are improved.

Description

Technical Field

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

[0002] Perovskite materials have excellent photovoltaic properties and can be made into perovskite solar cells through simple preparation processes (such as solution method, evaporation method, etc.), achieving high-efficiency and low-cost solar power generation. Among them, the efficiency of large-area preparation by solution method is low and the long-term stability of the battery is poor. In contrast, the evaporation method has multiple advantages such as high uniformity of large-area preparation, no solvent, conformal growth of thin films, and good compatibility.

[0003] However, the perovskite solar cells prepared by the evaporation method are still inferior to those prepared by the solution method. In the evaporation method, the organic salt cannot completely penetrate into the bottom of the inorganic layer, resulting in residual lead iodide at the bottom interface, which affects the photostability and photoelectric conversion efficiency of the perovskite film.

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

[0005] The embodiments of the present application provide a perovskite solar cell and a method for preparing the same, and a photovoltaic system to solve or alleviate one or more of the technical problems raised above.

[0006] As one aspect of an embodiment of the present application, an embodiment of the present application provides a method for preparing a perovskite solar cell, comprising: providing a substrate; forming a first transmission layer on one side of the substrate; Depositing chloride on a side of the first transmission layer away from the substrate to form a pretreatment layer; forming an intermediate layer on one side of the pre-treated layer, and performing an annealing treatment to form a perovskite layer; A second transmission layer and an electrode are sequentially formed on a side of the perovskite layer away from the first transmission layer.

[0007] Optionally, the pretreatment layer is formed by the following operations: Depositing chloride on a side of the first transmission layer away from the substrate by evaporation or spin coating to form a pretreatment layer; Among them, the evaporation adopts a first evaporation source, the first evaporation source includes the chloride, and the chloride includes one or more of formamidine chloride, methylamine chloride, rubidium chloride, potassium chloride, guanidine chloride, ethylammonium chloride, and magnesium chloride. The evaporation rate of the first evaporation source is 0.5~1 Å / s, and the evaporation thickness can be 5~15nm.

[0008] Optionally, an intermediate layer is formed on one side of the pretreatment layer, comprising: Depositing an inorganic layer on the side of the pretreatment layer away from the first transmission layer by dual-source evaporation; The organic layer is deposited on a side of the inorganic layer away from the pretreatment layer by single-source evaporation.

[0009] Optionally, the dual-source evaporation uses a second evaporation source and a third evaporation source; wherein the second evaporation source includes lead iodide, and the evaporation rate of the second evaporation source is 1~2Å / s; the third evaporation source includes one or more of cesium bromide and cesium iodide, and the evaporation rate of the third evaporation source is 0.1~1Å / s.

[0010] Optionally, the single-source evaporation uses a fourth evaporation source, and the fourth evaporation source includes one or more of formamidine iodide, potassium bromide, formamidine chloride, methylamine iodide, methylamine bromide, and methylamine chloride, and the evaporation rate of the fourth evaporation source is 0.5~1.5 Å / s.

[0011] Optionally, the annealing process includes: Performing a first annealing treatment on the pre-treatment layer and the intermediate layer; The pre-treated layer and the intermediate layer that have been subjected to the first annealing treatment are subjected to a second annealing treatment.

[0012] Optionally, the annealing temperature of the first annealing treatment is 100-120° C., the annealing time is 5-10 min, and the annealing environment is a nitrogen atmosphere.

[0013] Optionally, the annealing temperature of the second annealing treatment is 150-200° C., the annealing time is 10-30 min, and the annealing environment is an air atmosphere with a humidity of 30-40%.

[0014] As another aspect of the embodiment of the present application, the embodiment of the present application further provides a perovskite solar cell, including: substrate; A first transmission layer, disposed on one side of the substrate; a perovskite layer, disposed on a side of the first transmission layer away from the substrate; A second transmission layer is provided on a side of the perovskite layer away from the first transmission layer; an electrode, disposed on a side of the second transport layer away from the perovskite layer; Wherein, the perovskite layer includes chloride.

[0015] Optionally, the perovskite layer is formed by annealing a pretreatment layer and an intermediate layer; the pretreatment layer and the intermediate layer exist before annealing and form the perovskite layer after annealing; Wherein, the pretreatment layer is arranged on a side of the first transmission layer away from the substrate, the bottom boundary pretreatment layer comprises the chloride, and the thickness of the pretreatment layer is 5-15 nm; The intermediate layer comprises: an inorganic layer, disposed on a side of the pretreatment layer away from the first transmission layer, The organic layer is disposed on a side of the inorganic layer away from the pretreatment layer.

[0016] Optionally, the chloride includes one or more of formamidine chloride, methylamine chloride, rubidium chloride, potassium chloride, guanidine chloride, ethylammonium chloride, and magnesium chloride.

[0017] As another aspect of the embodiments of the present application, the embodiments of the present application also provide a photovoltaic system, including any of the above-mentioned perovskite solar cells.

[0018] The above technical solution adopted in the embodiment of the present application may have the following advantages: The embodiment of the present application forms a perovskite solar cell by preparing a substrate, a first transmission layer, a perovskite layer, a second transmission layer and an electrode. Specifically, the perovskite layer can be prepared by the following operations: first, a chloride is evaporated to form a pretreatment layer, an intermediate layer is formed on the surface of the pretreatment layer, and an annealing treatment is performed. Since the pretreatment layer is in contact with the bottom interface of the intermediate layer, the chloride therein can form an intermediate phase (chlorine-based perovskite) with the cations of the intermediate layer, and the chlorine-based perovskite can be used as a template for the crystallization of iodine-based perovskite, effectively controlling the growth and morphology of perovskite crystals, and improving the performance and stability of the battery. It can be seen that the embodiment of the present application forms a pretreatment layer in contact with the bottom interface of the intermediate layer by evaporating chloride, which can reduce the residual lead iodide on the bottom interface, promote the film formation of perovskite, and effectively improve the stability and performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 1 The flowchart of the method for preparing a perovskite solar cell according to the first embodiment of the present application is schematically shown.

[0021] Figure 2 The flowchart of preparing the pretreatment layer, the inorganic layer and the organic layer according to the first embodiment of the present application is schematically shown.

[0022] Figure 3 It is a schematic diagram of the structure of a perovskite solar cell provided according to Example 2 of the present application.

[0023] Description of reference numerals: 1 Substrate 2 First Transport Layer 3 Perovskite layer 4 Second Transport Layer 5 Electrodes 6 Buffer layer 31 Preprocessing layer 32 Inorganic layer 33 organic layer. DETAILED DESCRIPTION

[0024] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0025] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not mean that the present disclosure necessarily has the first element, component, region, layer or part.

[0026] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] The embodiment of the present application provides a perovskite solar cell and a preparation method thereof, and a photovoltaic system. In this technical solution: a pretreatment layer in contact with the bottom interface of the intermediate layer is formed by evaporating chloride, and the chloride can form an intermediate phase (chlorine-based perovskite) with the cations of the intermediate layer. The chlorine-based perovskite can be used as a template for the crystallization of iodine-based perovskite, effectively controlling the growth and morphology of the perovskite crystal, thereby forming a well-crystallized and highly uniform thin film, thereby improving the light stability and photoelectric conversion efficiency of the battery. See below for details.

[0029] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0030] Embodiment 1 Figure 1 The flowchart of the method for preparing a perovskite solar cell according to the first embodiment of the present application is schematically shown.

[0031] like Figure 1 As shown, the method for preparing the perovskite solar cell may include steps S100 to S108, wherein: Step S100 , providing a substrate.

[0032] Step S102, forming a first transmission layer on one side of the substrate.

[0033] Step S104 , chloride is deposited on a side of the first transmission layer away from the substrate to form a pretreatment layer.

[0034] Step S106 An intermediate layer is formed on one side of the pretreatment layer, and an annealing treatment is performed to form a perovskite layer.

[0035] Step S108 A second transport layer and an electrode are sequentially formed on a side of the perovskite layer away from the first transport layer.

[0036] In this embodiment, a substrate, a first transmission layer, a perovskite layer, a second transmission layer and an electrode are prepared, and the layers are stacked to form a perovskite solar cell. The perovskite layer is specifically prepared by the following operations: first, a chloride is evaporated to form a pretreatment layer, an intermediate layer is formed on the surface of the pretreatment layer, and an annealing treatment is performed. Since the pretreatment layer is in contact with the bottom interface of the intermediate layer, the chloride therein can form an intermediate phase (chlorine-based perovskite) with the cations of the intermediate layer, and the chlorine-based perovskite can be used as a template for the crystallization of iodine-based perovskite, effectively controlling the growth and morphology of perovskite crystals, thereby forming a well-crystallized and highly uniform thin film, and improving the light stability and photoelectric conversion efficiency of the battery. It can be seen that the embodiment of the present application forms a pretreatment layer in contact with the bottom interface of the intermediate layer by evaporating chloride, which can reduce the residual lead iodide on the bottom interface, promote the film formation of perovskite, and effectively improve the stability and performance of the battery.

[0037] Combine the following Figure 1 , each step in steps S100~S108 and other optional steps are explained in detail.

[0038] Step S100 , providing a substrate.

[0039] The substrate can be a transparent conductive substrate, or a silicon cell, a perovskite cell or other types of cell substrates, such as copper indium gallium selenide (CIGS), gallium nitride (GaN), etc. Among them, the transparent conductive substrate can be one or more of transparent glass or plastic substrates, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), indium zinc oxide (IZO), tungsten-doped indium oxide (IWO), and aluminum-doped zinc oxide (AZO). Single-junction perovskite solar cells can be prepared by using transparent conductive substrates. Silicon cells and other cell substrates can be used to prepare stacked perovskite solar cells, such as perovskite-silicon stacked cells, and the photoelectric conversion efficiency of the cell can be further improved by stacking technology.

[0040] Step S102 , forming a first transmission layer on one side of the substrate.

[0041] According to the different directions of charge transfer, perovskite solar cells can be divided into the formal structure nip type and the trans structure pin type. Among them, n represents the electron transport layer, i represents the perovskite layer, and p represents the hole transport layer. Taking the preparation of the trans structure pin type perovskite solar cell as an example, a first transport layer can be formed on one side or the conductive side of the substrate. The first transport layer is a hole transport layer, which can be used to extract and transport holes while blocking the migration of electrons and carrier recombination. Correspondingly, if a formal structure pin type perovskite solar cell is prepared, the first transport layer is an electron transport layer, which can be used to extract and transport photogenerated electrons to form an electric current. In some embodiments, the preparation method of the first transport layer includes but is not limited to solution spin coating, spray coating, sol-gel method, vacuum evaporation, and physical vapor deposition.

[0042] Step S104 , chloride is deposited on a side of the first transmission layer away from the substrate to form a pretreatment layer.

[0043] For example, a chloride can be deposited on the side of the first transmission layer away from the substrate by evaporation, spin coating, spraying, printing or physical vapor deposition to form a pretreatment layer. In an optional embodiment, the chloride can include formamidine chloride (FACl), methylamine chloride (MACl), rubidium chloride (RbCl), potassium chloride (KCl), guanidine chloride (GUACl), ethylammonium chloride (EACl), magnesium chloride (MgCl 2 ). These chlorides have high stability and are not easily decomposed or volatilized during evaporation, spin coating, etc., which helps to form a uniform and reliable pretreatment layer.

[0044] An exemplary protocol for preparing a pretreatment layer is provided below.

[0045] In an optional embodiment, chloride is deposited on the side of the first transport layer away from the substrate by evaporation or spin coating to form a pretreatment layer, wherein the evaporation uses a first evaporation source, the first evaporation source includes one or more of the above-mentioned chlorides, the evaporation rate of the first evaporation source is 0.5-1 Å / s, and the evaporation thickness can be 5-15 nm.

[0046] In this embodiment, a uniform and stable pretreatment layer can be formed on the surface of the first transmission layer by evaporation. Evaporation can also accurately control the thickness of the pretreatment layer to avoid affecting the crystallization of perovskite due to too thick a pretreatment layer, and failing to reduce the residual lead iodide at the bottom interface of the intermediate layer due to too thin a pretreatment layer.

[0047] Step S106 An intermediate layer is formed on one side of the pretreatment layer, and an annealing treatment is performed to form a perovskite layer.

[0048] The defect density of the purely inorganic perovskite layer is large, resulting in low photoelectric conversion efficiency. In order to improve the performance of the battery, the intermediate layer may include an inorganic layer and an organic layer. The inorganic salt and the organic salt react during the annealing process, which can effectively repair defects and optimize the lattice. The inorganic layer and the organic layer are deposited in sequence on one side of the pretreatment layer to form an intermediate layer. It should be noted that the preparation method of the inorganic layer and the organic layer can be selected according to actual needs, including but not limited to spin coating, evaporation, slit coating, scraping, spraying, screen printing, inkjet printing, etc. Taking the evaporation method as an example, the preparation methods of the inorganic layer and the organic layer are introduced respectively.

[0049] In an optional embodiment, if Figure 2 As shown, forming the intermediate layer on one side of the pretreatment layer may include: depositing an inorganic layer on the side of the pretreatment layer away from the first transmission layer by dual-source evaporation. Depositing an organic layer on the side of the inorganic layer away from the pretreatment layer by single-source evaporation. The dual-source evaporation may use a second evaporation source and a third evaporation source; the second evaporation source may include lead iodide (PbI 2 ), the evaporation rate can be 1~2Å / s. The third evaporation source can include one or more of cesium bromide (CsBr) and cesium iodide (CsI), and the evaporation rate is 0.1~1 Å / s. The single-source evaporation can use a fourth evaporation source, and the fourth evaporation source can include one or more of formamidine iodide (FAI), potassium amidine bromide (FABr), formamidine chloride (FACl), methylamine iodide (MAI), methylamine bromide (MABr), and methylamine chloride (MACl), and the evaporation rate is 0.5~1.5 Å / s.

[0050] In this embodiment, a plurality of different inorganic salts are deposited together by dual-source evaporation to form a high-quality, uniform inorganic layer, and the deposition rate of various materials can be precisely controlled, thereby effectively regulating the structure and performance of the inorganic layer. The inorganic layer is deposited on the pretreatment layer, so that the pretreatment layer can directly contact the bottom surface of the inorganic layer, and the chloride in the pretreatment layer can react with the inorganic cations (such as Pb 2+) forms a stable intermediate phase compound (chlorine-based perovskite). Chlorine-based perovskite can be used as a template for iodine-based perovskite to effectively control the growth and morphology of perovskite crystals, thereby forming a well-crystallized and highly uniform thin film, improving the light stability and photoelectric conversion efficiency of the battery; and some chlorine will overflow during the annealing process, facilitating the contact reaction of lead iodide (PbI2) and FAI (formamidine iodide), that is, promoting the reaction of the inorganic layer and the organic layer, further improving the crystal morphology and film uniformity, and further improving the light stability and photoelectric conversion efficiency of the battery. The composition and purity of the organic layer can be precisely controlled by single-source evaporation to ensure the quality and performance uniformity of the organic layer. After the inorganic layer and the organic layer are deposited to form an intermediate layer, the intermediate layer and the pretreatment layer can be annealed to fully react to form a high-quality and uniform perovskite film. The annealing process can be carried out directly in the air, or in multiple steps under multiple conditions (annealing environment, temperature, time) to regulate the annealing effect and optimize the quality of the perovskite layer.

[0051] An exemplary annealing treatment scheme is provided below.

[0052] In an optional embodiment, the annealing treatment may include: performing a first annealing treatment on the pre-treated layer and the intermediate layer; performing a second annealing treatment on the pre-treated layer and the intermediate layer after the first annealing treatment. The annealing temperature of the first annealing treatment is 100-120°C, the annealing time is 5-10 minutes, and the annealing environment is a nitrogen atmosphere. The annealing temperature of the second annealing treatment is 150-200°C, the annealing time is 10-30 minutes, and the annealing environment is an air atmosphere with a humidity of 30-40%.

[0053] In this embodiment, the annealing treatment is carried out in two steps: first, the annealing treatment is carried out in a nitrogen environment to promote the reaction of the pretreatment layer, the inorganic layer and the organic layer. Part of the chlorine will overflow during the annealing process to facilitate the lead iodide (PbI 2 ) and FAI (formamidine iodide), that is, promoting the reaction between the inorganic layer and the organic layer to preform perovskite. Then it is transferred to the air for annealing. The moisture in the air can dissolve part of the FAI in the organic layer, increase the diffusion of FAI, and further promote the reaction. The annealing temperature of 150~200℃ is the best temperature for perovskite film formation, so that a high-quality, uniform, and defect-free perovskite layer can be formed.

[0054] The above embodiment introduces how to prepare a perovskite layer. The following is an exemplary introduction to other preparation steps of a perovskite solar cell.

[0055] Step S108 A second transport layer and an electrode are sequentially formed on a side of the perovskite layer away from the first transport layer.

[0056] Taking the preparation of an inverted pin-type perovskite solar cell as an example, a second transport layer can be formed on the side of the perovskite layer away from the first transport layer. The second transport layer is an electron transport layer, which can be used to extract and transport photogenerated electrons to form an electric current. Correspondingly, if a formal pin-type perovskite solar cell is prepared, the second transport layer is a hole transport layer. An electrode can be formed on the side of the second transport layer away from the perovskite layer, which can be used to collect electrons and transmit them to an external circuit. In some embodiments, the preparation method of the electron transport layer includes but is not limited to solution spin coating, sol-gel method, physical vapor deposition, and vacuum deposition. The preparation method of the electrode includes but is not limited to physical vapor deposition, solution spin coating, vacuum evaporation, and solution printing.

[0057] Embodiment 2 like Figure 3 As shown, the embodiment of the present application further provides a perovskite solar cell. The perovskite solar cell may include: a substrate 1 , a first transmission layer 2 , a perovskite layer 3 , a second transmission layer 4 and an electrode 5 .

[0058] It should be noted that Figure 3 Only a single-junction perovskite solar cell with an inverted structure is schematically shown. In an optional embodiment, the perovskite solar cell may be a single-junction perovskite solar cell or a stacked perovskite solar cell. A single-junction perovskite solar cell has only one PIN junction. A stacked perovskite solar cell may be a perovskite stacked with a perovskite, a crystalline silicon or other battery, and may have multiple light-absorbing layers (multiple PIN junctions). Since various materials have different band gaps, stacks of different materials may absorb light of different spectra, further improving the photoelectric conversion efficiency. Of course, two perovskites with different band gaps may also be stacked to improve the cell efficiency. In an optional embodiment, the stacked perovskite solar cell may be a two-terminal stacked perovskite solar cell, a three-terminal stacked perovskite solar cell or a four-terminal stacked perovskite solar cell. In an optional embodiment, the perovskite solar cell may also be divided into a formal structure (nip type) and an inverted structure (pin type) according to different charge transfer directions.

[0059] The structure of each layer of the perovskite solar cell and its coordination with other layers will be further introduced as an example below.

[0060] The substrate 1 may be a transparent conductive substrate, or a silicon cell, a perovskite cell, or other types of cells, such as copper indium gallium selenide (CIGS), gallium nitride (GaN), etc., for preparing a single-junction or stacked perovskite solar cell. In some embodiments, the thickness of the substrate 1 may be 1 to 5 mm.

[0061] The first transmission layer 2 may be arranged on one side or the conductive side of the substrate 1, the perovskite layer 3 may be arranged on the side of the first transmission layer 2 away from the substrate 1, and the second transmission layer 4 may be arranged on the side of the perovskite layer 3 away from the first transmission layer 2. Wherein, the perovskite layer 3 may include chloride. Through the action of chloride, the residual lead iodide at the bottom interface can be reduced, the organic salt and the inorganic salt can be fully reacted, the defect density of the perovskite layer can be reduced, the growth and morphology of the perovskite crystal can be controlled, and the perovskite layer 3 can be ensured to be well crystallized and highly uniform, thereby improving the light stability and battery performance of the perovskite solar cell. Exemplarily, the perovskite layer 3 may be formed by annealing the pretreatment layer 31 and the intermediate layer. The intermediate layer may include an inorganic layer 32 and an organic layer 33. Wherein, the pretreatment layer 31 may include chloride. In an optional embodiment, the thickness of the pretreatment layer 31 may be 5 to 15 nm. If the pretreatment layer 31 is too thick, it will affect the crystallization of the perovskite, and if it is too thin, the residual lead iodide at the bottom interface of the inorganic layer cannot be reduced. In some embodiments, the thickness of the inorganic layer 32 may be 200-300 nm, and the thickness of the organic layer 33 may be 180-250 nm.

[0062] For the first transmission layer 2 and the second transmission layer 4: Figure 3 As shown, in the trans-structure pin-type perovskite solar cell, the first transport layer 2 corresponds to the hole transport layer, and the second transport layer 4 corresponds to the electron transport layer. In the regular structure pin-type perovskite solar cell, the first transport layer 2 corresponds to the electron transport layer, and the second transport layer 4 corresponds to the hole transport layer. Through the first transport layer 2 and the second transport layer 4, the electrons and holes generated by the perovskite layer 3 after light absorption can be effectively separated and transported, thereby generating current.

[0063] In an alternative embodiment, the hole transport layer may include nickel oxide (NiO x ) and a self-assembled material (SAM). The self-assembled material (SAM) includes one or more of [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz)), [4-(7H-dibenzocarbazole-7-yl)butyl]phosphonic acid (4PADCB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC). In some embodiments, the thickness of the hole transport layer may be 20 to 40 nm.

[0064] In an alternative embodiment, the electron transport layer may include tin oxide (such as SnO 2 ), titanium oxide (TiO2 ), fullerene (C 60 ) and its derivatives (C 70 In some embodiments, the thickness of the electron transport layer may be 12-30 nm.

[0065] In an optional embodiment, if Figure 3 As shown, the inverted pin-type perovskite solar cell may further include a buffer layer 6, which is disposed between the electron transport layer and the electrode 5 to adjust electron transport, optimize interface properties and improve stability, thereby further improving battery performance. The buffer layer 6 may include bathocuproine (BCP), atomic layer deposited tin dioxide (SnO 2 In some embodiments, the buffer layer 6 may have a thickness of 5-15 nm.

[0066] The electrode 5 may be disposed on a side of the second transport layer 4 away from the perovskite layer 3 for collecting and transporting carriers. The electrode 5 may include: a metal electrode; or a transparent conductive electrode. The metal electrode may include one of silver (Ag), copper (Cu), and aluminum (Al), and the transparent conductive electrode may include one of indium tin oxide (ITO), indium zinc oxide (IZO), tungsten-doped indium oxide (IWO), and aluminum-doped zinc oxide (AZO). In some embodiments, the thickness of the electrode may be 100 to 400 nm.

[0067] The present application will be further described below in conjunction with specific embodiments, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0068] [Example 1] like Figure 3 As shown, the specific structure of a perovskite solar cell (taking a trans-structure pin-type single junction as an example) can be: A substrate 1, a first transport layer 2 (such as a hole transport layer), a perovskite layer 3, a second transport layer 4 (such as an electron transport layer), a buffer layer 6, and an electrode 5 are stacked in sequence.

[0069] A specific preparation process of a perovskite solar cell can be: S200, depositing NiO on the transparent conductive substrate 1 by magnetron sputtering X , thickness is 25nm.

[0070] S201, NiO XThe self-assembled material Me-4PACz was deposited on the surface. The Me-4PACz was dissolved in ethanol at a concentration of 0.5 mg / mL. The spin coating speed was 3000 rpm / s. The substrate was annealed at 100° C. for 10 min to obtain a SAM layer to form a hole transport layer 2.

[0071] S202, FACl is evaporated on the surface of the SAM layer by an evaporation method to form a pretreatment layer 31, the evaporation rate is 1Å / s, and the thickness is 10nm.

[0072] S203, co-evaporating PbI on the surface of the pre-treated layer by evaporation method 2 , CsBr forms an inorganic layer 32, PbI 2 The evaporation rate is 2Å / s and the thickness is 180nm. The evaporation rate of CsBr is 0.4Å / s and the thickness is 36nm.

[0073] S204, depositing an organic layer 33 on the surface of the inorganic layer 32 by evaporation, with an evaporation rate of 1 Å / s and a thickness of 220 nm, to obtain a prefabricated perovskite layer (intermediate layer).

[0074] S205, the prefabricated perovskite layer is subjected to step-by-step annealing treatment, the annealing temperature in the glove box (nitrogen atmosphere) is 100°C, and the annealing time is 10 minutes. Then, 0.1 mL of propylene glycol (IPA) is used to clean the film at 3000 r / min for 10 seconds, and then annealed at 100°C for 3 minutes. Then, it is transferred to an air atmosphere with a humidity of 30-40%, the annealing temperature is 150°C, and the annealing time is 20 minutes to obtain the perovskite layer 3.

[0075] S206 , a 20 nm thick electron transport layer 4 and a 5 nm thick BCP buffer layer 6 are deposited on the surface of the perovskite layer 3 by a vapor deposition method.

[0076] S207, preparing Ag metal electrode 5 with a thickness of 100 nm by thermal evaporation method, and completing battery preparation.

[0077] [Example 2] The perovskite solar cell of Example 2 is prepared by referring to the preparation steps of Example 1, except that step S202 of Example 2 is: MACl (methylammonium chloride) is evaporated on the surface of the SAM layer to form a pretreatment layer 31, the evaporation rate is 1Å / s, and the thickness is 10nm.

[0078] [Example 3] The perovskite solar cell of Example 3 is prepared by referring to the preparation steps of Example 1, except that step S202 of Example 3 is: RbCl (rubidium chloride) is evaporated on the surface of the SAM layer to form a pretreatment layer 31, the evaporation rate is 1Å / s, and the thickness is 5nm.

[0079] [Example 4] The perovskite solar cell of Example 4 is prepared by referring to the preparation steps of Example 1, except that step S202 of Example 4 is: KCl (potassium chloride) is evaporated on the surface of the SAM layer to form a pretreatment layer 31 by evaporation method, the evaporation rate is 1Å / s, and the thickness is 5nm.

[0080] [Example 5] The perovskite solar cell of Example 5 is prepared by referring to the preparation steps of Example 1, except that step S202 of Example 5 is: MgCl is evaporated on the surface of the SAM layer by evaporation method. 2 (potassium chloride), the evaporation rate is 1Å / s, and the thickness is 5nm.

[0081] [Comparative Example] The perovskite solar cell of the comparative example is prepared by referring to the preparation method of the embodiment, except that the comparative example does not perform step S202, and directly proceeds to step S203 after step S201 is completed, and step S203 of the comparative example is: co-evaporating PbI on the surface of the SAM layer by evaporation method 2 , CsBr forms an inorganic layer 32, PbI 2 The evaporation rate is 2Å / s and the thickness is 180nm. The evaporation rate of CsBr is 0.4Å / s and the thickness is 36nm.

[0082] The following is a performance test of the perovskite solar cell provided in the embodiment of the present application and the comparative example, so as to obtain the open circuit voltage V of the corresponding battery device. oc , short circuit current density J sc , fill factor FF, photoelectric conversion efficiency PCE, the test results are shown in Table 1.

[0083] Table 1 Performance test results of perovskite solar cells of embodiments and comparative examples

[0084] It can be seen from Table 1 above that, compared with the comparative example, the perovskite solar cells of Examples 1-5 of the present application have higher short-circuit current, fill factor and photoelectric conversion efficiency, that is, have better battery performance.

[0085] In summary, the embodiment of the present application forms a pretreatment layer in contact with the bottom interface of the intermediate layer by evaporating chloride, which can reduce residual lead iodide on the bottom interface, promote perovskite film formation, and effectively improve the stability, photoelectric performance and repeatability of the battery.

[0086] The embodiment of the present application may also provide a photovoltaic module (not shown), including at least one battery string, the battery string including at least two perovskite solar cells as described above, and adjacent perovskite solar cells may be connected together by serial welding.

[0087] The embodiment of the present application can also provide a photovoltaic system, including the perovskite solar cell or photovoltaic module in any of the above embodiments. The advantages of the above perovskite solar cell or photovoltaic module are also possessed by the photovoltaic system, which will not be repeated here. The above photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic modules. For example, multiple photovoltaic modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0088] It should be noted that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0089] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when a specific feature, structure or characteristic is described in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0090] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0091] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a perovskite solar cell, characterized in that: include: providing a substrate; forming a first transmission layer on one side of the substrate; Depositing chloride on a side of the first transmission layer away from the substrate to form a pretreatment layer; forming an intermediate layer on one side of the pre-treated layer, and performing an annealing treatment to form a perovskite layer; A second transmission layer and an electrode are sequentially formed on a side of the perovskite layer away from the first transmission layer.

2. The preparation method according to claim 1, characterized in that: The pretreatment layer is formed by the following operations: Depositing chloride on a side of the first transmission layer away from the substrate by evaporation or spin coating to form a pretreatment layer; Among them, the evaporation adopts a first evaporation source, the first evaporation source includes the chloride, and the chloride includes one or more of formamidine chloride, methylamine chloride, rubidium chloride, potassium chloride, guanidine chloride, ethylammonium chloride, and magnesium chloride. The evaporation rate of the first evaporation source is 0.5~1 Å / s and the evaporation thickness is 5~15nm.

3. The preparation method according to claim 1, characterized in that: An intermediate layer is formed on one side of the pretreatment layer, comprising: Depositing an inorganic layer on the side of the pretreatment layer away from the first transmission layer by dual-source evaporation; The organic layer is deposited on a side of the inorganic layer away from the pretreatment layer by single-source evaporation.

4. The preparation method according to claim 3, characterized in that The dual-source evaporation adopts a second evaporation source and a third evaporation source; wherein the second evaporation source includes lead iodide, and the evaporation rate of the second evaporation source is 1~2Å / s; the third evaporation source includes one or more of cesium bromide and cesium iodide, and the evaporation rate of the third evaporation source is 0.1~1Å / s.

5. The preparation method according to claim 3, characterized in that The single-source evaporation adopts a fourth evaporation source, and the fourth evaporation source includes one or more of formamidine iodide, potassium bromide, formamidine chloride, methylamine iodide, methylamine bromide, and methylamine chloride. The evaporation rate of the fourth evaporation source is 0.5~1.5 Å / s.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The annealing treatment comprises: Performing a first annealing treatment on the pre-treatment layer and the intermediate layer; The pre-treated layer and the intermediate layer that have been subjected to the first annealing treatment are subjected to a second annealing treatment.

7. The preparation method according to claim 6, characterized in that: The annealing temperature of the first annealing treatment is 100-120° C., the annealing time is 5-10 min, and the annealing environment is a nitrogen atmosphere.

8. The preparation method according to claim 6, characterized in that: The annealing temperature of the second annealing treatment is 150-200° C., the annealing time is 10-30 minutes, and the annealing environment is an air atmosphere with a humidity of 30-40%.

9. A perovskite solar cell, characterized in that: include: substrate; A first transmission layer, disposed on one side of the substrate; a perovskite layer, disposed on a side of the first transmission layer away from the substrate; A second transmission layer is provided on a side of the perovskite layer away from the first transmission layer; an electrode, disposed on a side of the second transport layer away from the perovskite layer; Wherein, the perovskite layer includes chloride.

10. The perovskite solar cell according to claim 9, characterized in that: The perovskite layer is formed by annealing a pretreatment layer and an intermediate layer, wherein the pretreatment layer and the intermediate layer exist before annealing and form the perovskite layer after annealing; The pretreatment layer is disposed on a side of the first transmission layer away from the substrate, the pretreatment layer includes the chloride, and the thickness of the pretreatment layer is 5-15 nm; The intermediate layer comprises: an inorganic layer, disposed on a side of the pretreatment layer away from the first transmission layer, The organic layer is disposed on a side of the inorganic layer away from the pretreatment layer.

11. The perovskite solar cell according to claim 9 or 10, characterized in that: The chloride includes one or more of formamidine chloride, methylamine chloride, rubidium chloride, potassium chloride, guanidine chloride, ethylammonium chloride, and magnesium chloride.

12. A photovoltaic system, characterized in that: Comprising the perovskite solar cell according to any one of claims 9 to 11.

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