Perovskite solar cell and preparation method thereof

Abstract

The invention discloses a perovskite solar cell and a preparation method thereof, the perovskite cell comprises a substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer and a first electrode which are sequentially laminated, the electron transport layer comprises a first transport layer and a second transport layer, the second transport layer is located on the side, away from the substrate, of the first transport layer, and the hole transport layer is located on the side, away from the substrate, of the second transport layer. And the material of the second transmission layer comprises a bipyridine derivative. A second transmission layer in an electron transmission layer in the cell is a bipyridine derivative, the bipyridine derivative has a heterocyclic structure and shows pre-coordination of nitrogen, so that the bipyridine derivative can chelate Ag and release free electrons, and the free electrons are then absorbed by a first transmission layer to form n-type doping of the first transmission layer. The problem that the long-term operation stability of a perovskite solar cell is damaged due to a metal electrode in the prior art is solved.

Description

Technical Field

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

[0002] Despite the continuous improvement in certified power conversion efficiency (PCE) of tandem solar cells (TSCs), their commercial development is limited by the stability of their perovskite functional layers. This is because ion diffusion and chemical reactions between metal electrodes (i.e., Ag, Al, or Cu) and perovskites under built-in electric fields or illumination can lead to degradation of device performance. In particular, irreversible changes such as metal migration and electrode corrosion can cause far greater damage to the long-term operational stability of devices than the inherent degradation of perovskite materials. Summary of the invention

[0003] The present application provides a perovskite solar cell and a preparation method thereof, so as to solve the problem in the related art that the metal electrode of the perovskite solar cell damages the long-term operation stability of the device.

[0004] According to one aspect of the present application, a perovskite solar cell is provided, comprising a substrate, a hole transport layer, a perovskite absorption layer and an electron transport layer stacked in sequence, wherein the electron transport layer comprises a first transport layer and a second transport layer, the second transport layer is located on a side of the first transport layer away from the substrate, and the material of the second transport layer comprises a bipyridine derivative.

[0005] Optionally, the bipyridine derivative includes 4,4'-dicyano-2,2'-bipyridine.

[0006] Optionally, the material of the first transmission layer includes a fullerene derivative modified by a bipyridine derivative.

[0007] Optionally, the molar mass ratio of the fullerene derivative to the bipyridine derivative is 3:1 to 7:1.

[0008] Optionally, the thickness of the first transmission layer is 15 nm to 40 nm, and the thickness of the second transmission layer is 5 nm to 20 nm.

[0009] Optionally, the substrate includes any one of conductive glass and solar bottom cell.

[0010] According to another aspect of the present application, a method for preparing a perovskite solar cell is provided, which is used to prepare any one of the perovskite solar cells described above, and the preparation method comprises: providing a substrate; sequentially stacking a hole transport layer, a perovskite absorption layer and a first transport layer on the substrate; and forming a second transport layer comprising a bipyridine derivative on the first transport layer using a spin coating process.

[0011] Optionally, the step of forming the first transport layer or the second transport layer includes: providing a precursor solution of any transport layer; coating the precursor solution using a spin coating process, wherein the rotation speed of the spin coating process is 2000rpm~3000rpm, and the spin coating time is 30s~50s; heat treating the precursor solution using a thermal evaporation process, and the temperature of the thermal evaporation process is 40℃~120℃, and the time is 0~30min.

[0012] Optionally, the precursor solution for preparing the first transport layer is a first precursor solution, wherein the first precursor solution comprises the bipyridine derivative and a fullerene material, wherein the concentration of the fullerene material solution is 15 mg / mL to 25 mg / mL, and the molar concentration of the bipyridine derivative is 3×10 -3 mmol / mL~7×10 -3 mmol / mL.

[0013] Optionally, the precursor solution for preparing the second transport layer is a second precursor solution, and the second precursor solution includes the bipyridine derivative, wherein the concentration of the bipyridine derivative is 10 mg / mL to 20 mg / mL.

[0014] Applying the technical solution of the present application, a perovskite solar cell is provided, wherein the electron transport layer is located between the perovskite absorption layer and the first electrode, and the second transport layer in the electron transport layer is a bipyridine derivative, which has a heterocyclic structure and exhibits nitrogen pre-coordination, so that the bipyridine derivative can chelate Ag and release free electrons, which are then absorbed by the first transport layer to form n-type doping of the first transport layer. In addition, the bipyridine derivative can inhibit the mutual migration of metals and iodides and the formation of insulating compounds such as AgI. Therefore, the electron transport layer composed of the first transport layer and the bipyridine derivative layer can accelerate the electron extraction of the perovskite layer, reduce the accumulation of carriers at the interface, significantly inhibit charge recombination, and improve the stability of the perovskite solar cell, solving the problem that the metal electrode of the perovskite solar cell damages the long-term operation stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0016] Figure 1 is a schematic cross-sectional structure diagram of a single-section perovskite solar cell according to an embodiment of the present application;

[0017] Figure 2is a schematic cross-sectional structure diagram of another single-section perovskite solar cell according to an embodiment of the present application;

[0018] Figure 3 is a schematic diagram of a cross-sectional structure of a HTJ stacked perovskite solar cell according to an embodiment of the present application;

[0019] Figure 4 is a schematic diagram of a cross-sectional structure of a Topcon laminated perovskite solar cell according to an embodiment of the present application;

[0020] Figure 5 is a schematic cross-sectional structure diagram of an IBC stacked perovskite solar cell according to an embodiment of the present application;

[0021] Figure 6 It is a flow chart of a method for preparing a perovskite solar cell according to an embodiment of the present application.

[0022] The above drawings include the following reference numerals:

[0023] 10. substrate; 111. bottom TCO film layer; 112. first hydrogenated amorphous silicon layer; 1131. first intrinsic hydrogenated amorphous silicon layer; 1132. second intrinsic hydrogenated amorphous silicon layer; 114. single crystal silicon layer; 115. second hydrogenated amorphous silicon layer; 116. second electrode; 121. first substrate; 123. doped emission layer; 124. first passivation layer; 125. second doped layer; 126. silicon oxide layer; 127. polycrystalline silicon layer; 128. second passivation layer ; 129, third electrode; 131, second substrate; 132, front field layer; 133, third passivation layer; 134, emitter; 135, back field layer; 136, fourth passivation layer; 137, fourth electrode; 138, fifth electrode; 20, hole transport layer; 30, perovskite absorption layer; 40, electron transport layer; 41, first transport layer; 42, second transport layer; 50, first electrode; 60, first conductive layer; 70, buffer layer; 80, second conductive layer. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] As described in the background art, the ion diffusion and chemical reaction between the metal electrode (i.e., Ag, Al, or Cu) and the perovskite in the prior art perovskite solar cell structure under built-in electric field or illumination will lead to the attenuation of device performance. In particular, irreversible changes such as metal migration and electrode corrosion will cause far greater damage to the stability of long-term operation of the device than the inherent attenuation of the perovskite material. In order to solve the above problems, the present application provides a perovskite solar cell and a method for preparing the same.

[0028] According to one aspect of the present application, a perovskite solar cell is provided, such as Figure 1 As shown, the perovskite solar cell includes a substrate 10, a hole transport layer 20, a perovskite absorption layer 30, an electron transport layer 40 and a first electrode 50 which are sequentially stacked, wherein the electron transport layer 40 includes a first transport layer 41 and a second transport layer 42, the second transport layer 42 is located on the side of the first transport layer 41 away from the substrate 10, and the material of the second transport layer 42 includes a bipyridine derivative. In the perovskite solar cell, the second transport layer in the electron transport layer is a bipyridine derivative, which has a heterocyclic structure and exhibits nitrogen pre-coordination, so that the bipyridine derivative can chelate Ag and release free electrons, which are then absorbed by the first transport layer to form n-type doping of the first transport layer. In addition, the bipyridine derivative can inhibit the mutual migration of metals and iodides and the formation of insulating compounds such as AgI. Therefore, the electron transport layer composed of the first transport layer and the bipyridine derivative layer can accelerate the electron extraction of the perovskite layer, reduce the accumulation of carriers at the interface, significantly inhibit charge recombination, improve the stability of perovskite solar cells, and solve the problem of long-term operation stability of perovskite solar cells due to damage to the device by metal electrodes.

[0029] Specifically, bipyridine is an organic compound, which contains a pyridine ring in its chemical structure and is a nitrogen-containing aromatic compound. The presence of nitrogen in bipyridine can provide pre-coordination of nitrogen, while the presence of bipyridine ring in bipyridine can further strengthen the pre-coordination of nitrogen, enabling bipyridine derivatives to chelate Ag and release free electrons.

[0030] In some alternative embodiments, the bipyridine derivative includes 4,4'-dicyano-2,2'-bipyridine.

[0031] Specifically, 4,4'-Dicyano-2,2'-Bipyridine (DCBP) is a bipyridine. The DCBP molecule has nitrogen ions at the relative positions of the two benzene rings. The nitrogen ions are the main binding points of metals, especially Ag, which enable the DCBP molecule to chelate metals and release free electrons. The reaction formula is as follows:

[0032]

[0033] The released free electrons are absorbed by the first transport layer in the electron transport layer, causing the first transport layer to form n-type doping, thereby accelerating the electron body region of the perovskite absorption layer, reducing carrier accumulation at the interface, and inhibiting charge recombination. In addition, the metal electrode is consumed by the second transport layer including DCBP, preventing ion diffusion and chemical reactions between the metal electrode and the perovskite, thereby protecting the stability of the perovskite solar cell. Moreover, DCBP can inhibit the mutual migration of metal ions and iodide and the formation of insulating compounds such as AgI, thereby improving the electron transport efficiency of the electron transport layer, and thus improving the photoelectric conversion efficiency of the perovskite solar cell.

[0034] In addition, in the structure of perovskite solar cells, a buffer layer is added on the electron transport layer and between the electrodes to reduce the impact of the interaction between adjacent layers, reduce the defect density of the device, and thereby improve the overall phase ratio and stability of the perovskite solar cell. The DCBP layer can also act as a buffer layer, improving the contact between the first transport layer and the buffer layer, reducing the carrier transport barrier, and promoting the transport of carriers. Moreover, during the preparation process, DCBP can also serve as a protective layer for the first transport layer to prevent damage from other chemical elements or preparation processes.

[0035] In some other optional embodiments, the material of the first transport layer includes a fullerene derivative modified with a bipyridine derivative.

[0036] Specifically, fullerene is a hollow molecule composed entirely of carbon, which is spherical, ellipsoidal, cylindrical or tubular in shape. Fullerene can be divided into C 20 , C 60 , C 70 , C 76 , C 80The fullerene derivatives mentioned above may include [6,6]-phenyl-C 61 -isomethyl-6,6-phenyl-C71-butyrate or isomethyl-6,6-phenyl-C71-butyrate ([6,6]-Phenyl-C 61 -Butyric Acid MethylEster or [6,6]-Phenyl-C 71 -Butyric Acid Methyl Ester, referred to as PCBM), PCBM has a conjugated cage-like carbon molecular structure of fullerene, which enables it to have good electron accommodating capacity and high electron mobility. The first transport layer is a functional layer of the electron transport layer, which is mainly used to transport electrons and improve the mobility of electrons.

[0037] Exemplarily, PCBM material modified by DCBP is used as the first transport layer in the electron transport layer. PCBM material modified by DCBP has a heterocyclic structure and can also show nitrogen pre-coordination, so that the first transport layer can chelate Ag and release free electrons, which are then collected by PCBM to form n-doping of PCBM. The n-doped PCBM and DCBP layer can further accelerate the electron extraction of the perovskite layer, reduce the accumulation of carriers at the interface, and significantly inhibit charge recombination. In addition, DCBP shows a strong interaction with iodine ions, which can effectively block the diffusion of iodine ions and prevent them from invading the electrode, avoiding the formation of insulating AgI, preventing insulating compounds such as AgI from reducing the transmission efficiency of the electrode, and improving the conversion efficiency of perovskite solar cells.

[0038] As a preferred embodiment, PCBM material modified by DCBP is used as the first transmission layer, and DCBP is used as the second transmission layer, wherein the PCBM film modified by DCBP can accelerate the electron extraction of the perovskite layer, reduce the accumulation of carriers on the interface, and inhibit charge recombination; the DCBP layer consumes the metal ions of the electrode, and can inhibit the mutual migration of metal ions and iodide and the formation of insulating compounds such as AgI. The combination of PCBM modified by DCBP and DCBP accelerates the electron extraction of the perovskite layer in the perovskite battery, reduces the accumulation of carriers on the interface, inhibits charge recombination, improves the conductivity, and improves the stability of the device.

[0039] In some optional embodiments, the molar mass ratio of the fullerene derivative to the bipyridine derivative is 3:1 to 7:1.

[0040] Specifically, the molar mass ratio of the fullerene derivative to the bipyridine derivative is 3:1 to 7:1. The bipyridine derivative can better adjust the performance of the fullerene derivative to obtain a more stable fullerene derivative modified by the bipyridine derivative. At the same time, the bipyridine derivative chelates with metal ions and releases free electrons, which can be more absorbed by the fullerene derivative, and there will be no situation where too many free electrons cannot be absorbed.

[0041] In some optional embodiments, the thickness of the first transmission layer is 15 nm to 40 nm, and the thickness of the second transmission layer is 5 nm to 20 nm.

[0042] Specifically, the thickness of the electron transport layer has an important influence on the photoelectric conversion efficiency of the perovskite solar cell. The increase in the thickness of the electron transport layer will cause the electron transmission path to become longer, increase the scattering and loss of electrons, and thus reduce the conductivity of the device; the reduction in the thickness of the electron transport layer will lead to the obstruction of electron transmission, affecting the transmission efficiency of electrons, and will also cause poor heat dissipation inside the device, affecting the stability and service life of the perovskite solar cell. The first transport layer is a functional layer for electron transmission. The thickness of the first transport layer is set to 15nm~40nm, which can ensure that the electron transport layer has a strong electron transmission efficiency, thereby ensuring the conversion efficiency of the battery and increasing the process window. In addition, while transmitting electrons, the second transport layer also plays a role in blocking the transmission and buffering of the electrode metal. The thickness of the second transport layer is 5nm~20nm, which can ensure that the bipyridine derivative chelates with Ag to release free ions, and at the same time, increase the process window.

[0043] Among them, the thickness of the first transmission layer can be 15nm, 20nm, 25nm, 30nm, 35nm and 40nm, the thickness of the second transmission layer is 5nm, 10nm, 15nm and 20nm, and the thickness of the first transmission layer and the thickness of the second transmission layer can be automatically matched.

[0044] In some optional embodiments, the substrate includes any one of conductive glass and a solar bottom cell.

[0045] Specifically, the electron transport layer composed of the first transport layer and the second transport layer including the bipyridine derivative is not only used in single-cell perovskite cells, but also in tandem perovskite cells, both of which can reduce the accumulation of carriers at the interface, significantly inhibit charge recombination, and improve the stability of perovskite solar cells.

[0046] Exemplarily, the perovskite solar cell of the present application is as follows Figure 1The perovskite single-cell solar cell shown, wherein the substrate 10 may include a glass substrate, specifically, the perovskite solar cell may include FTO conductive glass, ITO conductive glass, AZO conductive glass and a conductive flexible substrate. A hole transport layer 20, a perovskite absorption layer 30, an electron transport layer 40 and a first electrode 50 are sequentially stacked on the substrate 10, wherein the electron transport layer 40 includes a first transport layer 41 and a second transport layer 42 including a bipyridine derivative material, to form a perovskite single-cell solar cell structure. The preparation process of the perovskite single-cell solar cell is mature, large-area preparation can be achieved, and it has high stability.

[0047] Specifically, Figure 2 As shown, a first conductive layer 60 is formed on a glass substrate 10, and the first conductive layer 60 has a stacked hole transport layer 20, a perovskite absorption layer 30, an electron transport layer 40 and a first electrode 50, wherein the electron transport layer 40 includes a first transport layer 41 and a second transport layer 42 including a bipyridine derivative material, and the material of the first conductive layer 60 may include a transparent conductive oxide material. The transparent conductive oxide film can improve the conductive efficiency of a single solar cell due to its low resistivity and high transmittance in the visible light range.

[0048] In another example, the perovskite solar cell in the present application is a perovskite laminated solar cell structure. Specifically, the substrate is a solar bottom cell, wherein the solar bottom cell includes an intrinsic thin film heterojunction (Heterojunction with Intrinsic Thin-film, referred to as HJT) bottom cell, i.e., a solar crystalline silicon bottom cell, an oxide layer passivated contact (Tunnel Oxide Passivated Contact, referred to as Topcon) bottom cell, an interdigitated back contact (Interdigitated Back Contact, referred to as IBC) bottom cell and an all back contact solar cell (All Back Contact, referred to as ABC) bottom cell, wherein the ABC solar cell is based on N-type substrate silicon wafer technology, and is a new type of cell structure technology developed on the basis of a back contact type solar cell structure, which has a higher opening voltage and fill factor, better graphic technology, and a grid-free structure that enables the cell to have a better light absorption ability, thereby achieving a high conversion efficiency in the current mass-producible cell structure.

[0049] Specifically, the substrate 10 in the perovskite solar cell can be a HJT bottom cell, such as Figure 3As shown, the HJT bottom cell may include: an underlying TCO film layer 111, and a first hydrogenated amorphous silicon layer 112, a first intrinsic hydrogenated amorphous silicon layer 1131, a single crystal silicon layer 114, a second intrinsic hydrogenated amorphous silicon layer 1132, and a second hydrogenated amorphous silicon layer 115, which are sequentially formed and stacked on the first surface of the underlying TCO film layer 111 along a direction perpendicular to the first surface. The surface of the second hydrogenated amorphous silicon layer 115 facing away from the underlying TCO film layer 111 is the front side of the bottom cell, that is, the front side of the substrate 10. The solar bottom cell may also include a second electrode 116 formed on the back side of the underlying TCO film layer 111.

[0050] Specifically, the substrate 10 in the perovskite solar cell can be a Topcon bottom cell, such as Figure 4 As shown, the Topcon bottom battery may include: a first substrate 121, and the first substrate 121 has a relative front and back side, and a first doped emission layer 123 and a first passivation layer 124 of a first doping type are stacked on the front side of the first substrate 121 along a direction perpendicular to the front side; and a second doped layer 125, a silicon oxide layer 126, a second doped type polysilicon layer 127, a second passivation layer 128 and a third electrode 129 are stacked on the back side of the first substrate along a direction perpendicular to the back side.

[0051] Specifically, the substrate 10 in the perovskite solar cell can be an IBC bottom cell, such as Figure 5 As shown, the IBC bottom cell may include: providing a second substrate 131 having a first doping type, forming a front field layer 132 having the first doping type on the front side of the second substrate 131, and forming a third passivation layer 133 on the front field layer 132; forming an emitter 134 of the second doping type and a back field layer 135 of the first doping type alternately arranged on the back side of the second substrate 131, forming a fourth passivation layer 136 on the side of the emitter 134 and the back field layer 135 away from the second substrate 131, and forming a fourth electrode 137 and a fifth electrode 138 penetrating the fourth passivation layer 136 in the fourth passivation layer 136, wherein the fourth electrode 137 is connected to the emitter 134, and the fifth electrode 138 is connected to the back field layer 135.

[0052] In addition, if Figures 3 to 5As shown, a first conductive layer 60, a hole transport layer 20, a perovskite absorption layer 30, an electron transport layer 40 and a first electrode 50 are arranged on the surface of the solar bottom cell, i.e., the substrate 10, wherein the material of the electron transport layer 40 in the perovskite solar cell includes a first transport layer 41 and a second transport layer 42 including a bipyridine derivative, constituting a perovskite laminated solar cell structure. The perovskite laminated solar cell structure combines the advantages of perovskite solar cells and traditional HJT cells, Topcon cells and IBC cells, broadens the absorption spectrum of solar cells, and obtains a higher photoelectric conversion efficiency. Among them, the function of the above-mentioned first conductive layer 60 is to form an electrical connection between the perovskite top cell and the crystalline silicon bottom cell, effectively recombine electrons and holes with minimal resistance loss, and ensure high optical transparency in the long-wave band. The material of the first conductive layer 60 includes, but is not limited to, one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped indium (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO), and is not specifically limited in the present application.

[0053] In other optional embodiments, such as Figures 2 to 5 As shown, the above-mentioned perovskite solar cell structure also includes: a buffer layer 70 and a second conductive layer 80, wherein the buffer layer 70 and the second conductive layer 80 are stacked between the electron transport layer 40 and the first electrode 50, the buffer layer 70 contacts the electron transport layer 40, and the second conductive layer 80 contacts the first electrode 50.

[0054] Specifically, the material of the second conductive layer includes, but is not limited to, transparent conductive oxides, which have low resistivity and high transmittance in the visible light range, and can improve the photoelectric conversion efficiency of solar cells. Among them, transparent conductive oxides include, but are not limited to, one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO). Those skilled in the art can make appropriate selections based on product requirements, and this application does not make specific restrictions. In the perovskite solar cell structure, the first conductive layer and the second conductive layer have good conductivity and transparency, can effectively transfer electrons and allow light to penetrate into the perovskite layer, and the second conductive layer also protects the internal structure of the perovskite solar cell to prevent it from being eroded or damaged by the external environment.

[0055] In addition, the function of the buffer layer is to reduce the mutual influence between the electron transport layer and the first electrode, reduce the defect density of the battery, and improve the overall efficiency and stability of the battery. The material of the buffer layer can include but is not limited to SnO2, TiO2, C 60The combination of one or more materials of PCBB-2CN-2C8 is not specifically limited in this application.

[0056] In some optional embodiments, the materials of the first electrode and the second electrode include but are not limited to a combination of one or more materials of Au, Ag, Cu and Al, which is not specifically limited in the present application.

[0057] According to another aspect of the present application, a method for preparing a perovskite solar cell is provided, such as Figure 6 As shown, including:

[0058] Step S101: providing a substrate;

[0059] Step S102: forming a hole transport layer, a perovskite absorption layer, a first transport layer, a second transport layer and a first electrode in sequence on a substrate, wherein the material of the second transport layer includes a bipyridine derivative.

[0060] The preparation method of the above-mentioned perovskite solar cell of the present application is adopted, and a bipyridine derivative is used as the material of the second transport layer in the electron transport layer, wherein the bipyridine derivative has a heterocyclic structure and exhibits pre-coordination of nitrogen, so that the bipyridine derivative can chelate Ag and release free electrons, which are then absorbed by the first transport layer to form n-type doping of the first transport layer. In addition, the bipyridine derivative can inhibit the mutual migration of metals and iodides and the formation of insulating compounds such as AgI. Therefore, the electron transport layer composed of the first transport layer and the bipyridine derivative layer can accelerate the electron extraction of the perovskite layer, reduce the accumulation of carriers at the interface, significantly inhibit charge recombination, and improve the stability of the perovskite solar cell, solving the problem that the metal electrode of the perovskite solar cell damages the long-term operation stability of the device.

[0061] The following will describe in more detail the exemplary embodiments of the method for preparing the perovskite solar cell provided by the present application in conjunction with the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art.

[0062] To get Figures 1 to 5 The structure of the perovskite solar cell shown in the figure, first, step S101 is performed: providing a substrate.

[0063] For example, Figure 1 or Figure 2As shown, the substrate 10 may include a glass substrate, and specifically, the glass substrate may include FTO conductive glass, ITO conductive glass, AZO conductive glass, or a conductive flexible substrate. Figure 3 As shown, the substrate 10 may also include a solar crystalline silicon bottom cell of a HTJ bottom cell. Specifically, the silicon crystalline bottom cell includes: a bottom TCO film layer 111, and a first hydrogenated amorphous silicon layer 112, a first intrinsic hydrogenated amorphous silicon layer 1131, a single crystal silicon layer 114, a second intrinsic hydrogenated amorphous silicon layer 1132 and a second hydrogenated amorphous silicon layer 115 which are stacked in sequence on the first surface of the bottom TCO film layer 111 along a direction perpendicular to the first surface. The surface of the second hydrogenated amorphous silicon layer 115 facing away from the bottom TCO film layer 111 is the bottom cell, i.e., the front side of the substrate 10. The solar bottom cell may also include a second electrode 116 formed on the back side of the bottom TCO film layer 111.

[0064] In the perovskite tandem cell, a tunneling layer is required to electrically connect the crystalline silicon bottom cell and the perovskite cell. The material of the tunneling layer includes, but is not limited to, one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO), which can effectively recombine electrons and holes with minimal resistance loss and ensure high optical transparency in the long-wave band.

[0065] In other embodiments, Figures 4 to 5 As shown, the substrate 10 also includes Topcon bottom batteries, IBC bottom batteries and ABC bottom batteries. The preparation methods of the above bottom batteries are the same as the preparation methods in the prior art, and are not described in detail in this application.

[0066] Then, on the provided substrate 10, step S102 is performed: a hole transport layer 20, a perovskite absorption layer 30, a first transport layer 41, a second transport layer 42 and a first electrode 50 are sequentially stacked on the substrate 10, wherein the material of the second transport layer 42 includes a bipyridine derivative.

[0067] Specifically, the above step S102 may include the following steps:

[0068] First, perform step S1021: form a hole transport layer 20, wherein the material of the hole transport layer 20 includes but is not limited to one or more of 2PACz, Me-2PACz, MeO-2PACz, Me-4PACz and MeO-4PACz, which is not specifically limited in this application, and the process method for preparing the hole transport layer 20 includes but is not limited to spin coating, evaporation, and chain immersion, which is not specifically limited in this application.

[0069] Then, step S1022 is performed: forming a perovskite absorption layer 30 , wherein the band gap range of the perovskite absorption layer 30 is 1.60 eV to 1.70 eV.

[0070] Specifically, the process of forming the perovskite absorption layer 30 includes but is not limited to deposition, spraying, spin coating, thermal evaporation or screen printing followed by low temperature (eg, <150° C.) heat treatment.

[0071] Then, step S1023 is performed: forming a first transmission layer 41 .

[0072] Specifically, the step of forming the first transport layer 41 includes: first, providing a first precursor solution of the first transport layer; the first precursor solution includes a bipyridine derivative and a fullerene material, wherein the solution concentration of the fullerene material is 15 mg / mL to 25 mg / mL, and the molar concentration of the bipyridine derivative is 3×10 -3 mmol / mL~7×10 -3 mmol / mL; then, the precursor solution is coated by a spin coating process, wherein the rotation speed of the spin coating process is 2000rpm~3000rpm, and the spin coating time is 30s~50s; finally, the precursor solution is heat treated by a thermal evaporation process, and the temperature of the thermal evaporation process is 40℃~120℃, and the time is 0~30min.

[0073] Then, step S1024 is performed: forming a second transmission layer 42 .

[0074] Specifically, the steps of forming the second transport layer 42 include: first, providing a second precursor solution of the second transport layer; the second precursor solution includes a bipyridine derivative, and the concentration of the bipyridine derivative is 10 mg / mL to 20 mg / mL; then, the precursor solution is coated by a spin coating process, wherein the rotation speed of the spin coating process is 2000 rpm to 3000 rpm, and the spin coating time is 30s to 50s; finally, the precursor solution is heat-treated by a thermal evaporation process, and the temperature of the thermal evaporation process is 40°C to 120°C, and the time is 0 to 30min.

[0075] Then, step S1025 is performed: forming the first electrode 50 .

[0076] Specifically, the material of the first electrode 50 includes but is not limited to Au, Ag and Cu, and the process method for preparing the first electrode 50 includes but is not limited to screen printing, thermal evaporation or deposition process. The material and preparation method of the first electrode 50 are not specifically limited in this application.

[0077] In some optional embodiments, a first conductive layer 60 is formed between the substrate 10 and the hole transport layer 20 by a deposition process, and a buffer layer 70 and a second conductive layer 80 are formed between the second transport layer 42 and the first electrode 50 by a deposition process, wherein the buffer layer 70 is used for the mutual influence between the electron transport layer 40 and the first electrode 50, reducing the defect density of the battery and improving the overall efficiency and stability of the battery. The first conductive layer 60 and the second conductive layer 80 have good conductivity and transparency, can effectively transfer electrons and allow light to penetrate into the perovskite layer, and at the same time play a role in protecting the perovskite layer to prevent it from being eroded or damaged by the external environment. Among them, the materials of the first conductive layer 60 and the second conductive layer 80 include but are not limited to one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO), so as to improve the photoelectric conversion efficiency of solar cells, and the materials of the buffer layer 70 may include but are not limited to SnO2, TiO2, C 60 The combination of one or more materials of PCBB-2CN-2C8 is not specifically limited in this application.

[0078] Specifically, the above-mentioned deposition processes include but are not limited to physical vapor deposition (PVD), chemical vapor deposition (CVD) and atomic layer deposition (ALD), among which physical vapor deposition (PVD) includes but is not limited to magnetron sputtering process, reactive sputtering process, DC sputtering process, AC sputtering process, vacuum coating process, arc evaporation process, chemical vapor deposition (CVD) includes but is not limited to plasma enhanced chemical vapor deposition (PECVD), metal organic compound chemical vapor deposition (MOCVD), laser induced chemical vapor deposition (LCVD), and technical personnel in this field can make reasonable selections according to actual needs, and no specific limitation is made without application.

[0079] The crystalline silicon stacked solar cell and the preparation method thereof provided by the present application will be further described below in combination with embodiments and comparative examples.

[0080] Example 1

[0081] This embodiment provides Figure 3 The method for preparing the perovskite crystalline silicon tandem cell with a double-layer electron transport layer shown comprises the following steps:

[0082] A crystalline silicon bottom cell, i.e., a substrate 10, is provided; a boron diffusion layer is formed on an N-type silicon wafer by a laser grooving and local diffusion process, and the borosilicate glass is removed and the silicon wafer is cleaned to form a single crystal silicon layer 114; a first intrinsic hydrogenated amorphous silicon layer 1131 and a second intrinsic hydrogenated amorphous silicon layer 1132 are formed on two opposite surfaces of the single crystal silicon layer 114 by a plasma vapor deposition process, and a P-type first hydrogenated amorphous silicon layer 112 is formed on the surface of the first intrinsic hydrogenated amorphous silicon layer 1131 and a P-type first hydrogenated amorphous silicon layer 1132 is formed on the surface of the second intrinsic hydrogenated amorphous silicon layer 1132 by a plasma vapor deposition process. An N-type second hydrogenated amorphous silicon layer 115 is formed on the surface of the hydrogenated amorphous silicon layer 1132, a bottom TCO film layer 111 is formed on the surface of the first hydrogenated amorphous silicon layer 112 away from the single crystal silicon layer 114 by a magnetron sputtering process, a second electrode 116 is formed on the surface of the bottom TCO film layer 111 away from the single crystal silicon layer 114 by screen printing and high-temperature sintering, the material of the second electrode 116 is Ag, and an indium tin oxide (ITO) film layer is formed on the surface of the second hydrogenated amorphous silicon layer to form a tunneling layer, so as to prepare a crystalline silicon bottom cell;

[0083] Using a magnetron sputtering process, ITO is deposited on the provided crystalline silicon bottom cell, i.e., the substrate 10, to form a first conductive layer 60;

[0084] A 2PACz layer is prepared on the first conductive layer 90 by a spin coating process, with a thickness of 40 nm, to form a hole transport layer 20;

[0085] A perovskite absorption layer 30 is formed on the hole transport layer 20 by a deposition process, and the thickness is 300 nm;

[0086] A first precursor solution of the first transport layer 41 is provided, wherein the concentration of PCBM in the first precursor solution is 20 mg / mL, and the molar concentration of DCBP is 5×10 -3 mmol / mL, the first precursor solution is coated by a spin coating process, the rotation speed of the spin coating process is 2500rpm, and the spin coating time is 40s; the first precursor solution is evaporated by a thermal evaporation process, the temperature of the thermal evaporation process is 80°C, and the time is 20min, to form a first transmission layer 41 with a thickness of 30nm;

[0087] A second precursor solution of the second transport layer 42 is provided, wherein the molar concentration of DCBP in the second precursor solution is 15×10 -3 mg / mL, the second precursor solution is coated by a spin coating process, the rotation speed of the spin coating process is 2500 rpm, and the spin coating time is 40 s; the second precursor solution is evaporated by a thermal evaporation process, the temperature of the thermal evaporation process is 80° C., and the time is 20 min, to form a second transmission layer 42 with a thickness of 10 nm;

[0088] SnO2 is deposited on the second transmission layer 42 by an atomic deposition process with a thickness of 50 nm to form a buffer layer 70;

[0089] An ITO layer with a thickness of 40 nm is formed on the buffer layer 70 by a deposition process to form a second conductive layer 80;

[0090] The first electrode 50 is formed on the second conductive layer 80 by magnetron sputtering process, with a thickness of 40 nm and made of Ag.

[0091] Example 2

[0092] The difference between this embodiment and embodiment 1 is that the rotation speed of the spin coating process for preparing the first transmission layer 41 and the second transmission layer 42 is 2000 rpm, and the spin coating time is 30 s; the temperature of the thermal evaporation process is 40° C., and the time is 5 min.

[0093] Example 3

[0094] The difference between this embodiment and implementation 1 is that the rotation speed of the spin coating process for preparing the first transmission layer 41 and the second transmission layer 42 is 3000 rpm, and the spin coating time is 50 s; the temperature of the thermal evaporation process is 120° C., and the time is 30 min.

[0095] Example 4

[0096] The difference between this embodiment and embodiment 1 is that the rotation speed of the spin coating process for preparing the first transmission layer 41 and the second transmission layer 42 is 1000 rpm, and the spin coating time is 20 s; the temperature of the thermal evaporation process is 150° C., and the time is 50 min.

[0097] Example 5

[0098] The difference between this embodiment and embodiment 1 is that the concentration of PCBM solution in the first precursor is 35 mg / mL, and the molar concentration of DCBP is 8×10 -3 mmol / mL; the concentration of DCBP in the second precursor solution is 15 mg / mL.

[0099] Example 6

[0100] The difference between this embodiment and embodiment 1 is that the concentration of PCBM solution in the first precursor is 20 mg / mL, and the molar concentration of DCBP is 5×10 -3 mmol / mL; the concentration of DCBP in the second precursor solution is 30 mg / mL.

[0101] Example 7

[0102] The difference between this embodiment and embodiment 1 is that the rotation speed of the spin coating process for preparing the first transmission layer 41 and the second transmission layer 42 is 3000 rpm, and the spin coating time is 50 s; the temperature of the thermal evaporation process is 120°C, and the time is 30 min; the solution concentration of PCBM in the first precursor is 35 mg / mL, and the molar concentration of DCBP is 8×10 -3 mmol / mL; the concentration of DCBP in the second precursor solution is 30 mg / mL; the concentration of DCBP in the second precursor solution is 30 mg / mL.

[0103] Example 8

[0104] The difference between this embodiment and embodiment 1 is that the first precursor solution does not contain DCBP.

[0105] Comparative Example 1

[0106] The difference between this comparative example and implementation 1 is that the first precursor solution does not contain DCBP, and the second transport layer is not prepared.

[0107] The spectrum distribution is AM1.5G and the light intensity is 100mw / cm 2 The Oriel 300W solar simulator was used as the light source to test the photoelectric performance of the laminated solar cells obtained in the above Examples 1 to 4 and Comparative Example 1. The JV curve was measured by a Keithly 2400 digital source meter, and the photoelectric performance test parameters were obtained, as shown in Table 1:

[0108] Table 1

[0109]

[0110] From the results in Table 1, it can be seen that compared with Comparative Example 1, the open circuit voltage Voc, short circuit current density Jsc and conversion efficiency PCE of the stacked solar cells based on the multi-layer hole transport layer of Examples 1 to 7 are significantly improved, indicating that the material of the first transport layer in the electron transport layer is a fullerene derivative modified by a bipyridine derivative, and the material of the second transport layer is a bipyridine derivative. The photoelectric conversion efficiency is improved. In addition, compared with Comparative Example 1, the open circuit voltage Voc, short circuit current density Jsc, fill factor FF and conversion efficiency PCE of the stacked solar cell based on the multi-layer hole transport layer of Example 8 are all improved, indicating that the photoelectric conversion efficiency can be improved when the material of the second transport layer in the electron transport layer of the solar cell is a bipyridine derivative.

[0111] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0112] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A perovskite solar cell, characterized in that: It includes a substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer and a first electrode which are stacked in sequence, wherein the electron transport layer includes a first transport layer and a second transport layer, the second transport layer is located on a side of the first transport layer away from the substrate, and the material of the second transport layer includes a bipyridine derivative.

2. The perovskite solar cell according to claim 1, characterized in that The bipyridine derivatives include 4,4'-dicyano-2,2'-bipyridine.

3. The perovskite solar cell according to claim 1, characterized in that The material of the first transport layer includes a fullerene derivative modified by a bipyridine derivative.

4. The perovskite solar cell according to claim 3, characterized in that: The molar mass ratio of the fullerene derivative to the bipyridine derivative is 3:1 to 7:

1.

5. The perovskite solar cell according to claim 1, characterized in that: The thickness of the first transmission layer is 15 nm to 40 nm, and the thickness of the second transmission layer is 5 nm to 20 nm.

6. The perovskite solar cell according to claim 1, characterized in that: The substrate includes any one of conductive glass and a solar bottom cell.

7. A method for preparing a perovskite solar cell, characterized in that: Used to prepare the perovskite solar cell according to any one of claims 1 to 6, the preparation method comprising: providing a substrate; A hole transport layer, a perovskite absorption layer, a first transport layer, a second transport layer and an electrode are sequentially stacked on the substrate, wherein the material of the second transport layer includes a bipyridine derivative.

8. The preparation method according to claim 7, characterized in that: The step of forming the first transmission layer or the second transmission layer comprises: providing a precursor solution of any transport layer; The precursor solution is coated by a spin coating process, wherein the rotation speed of the spin coating process is 2000 rpm to 3000 rpm and the spin coating time is 30 s to 50 s; The precursor solution is heat-treated by a thermal evaporation process, wherein the temperature of the thermal evaporation process is 40° C. to 120° C. and the time is 5 min to 30 min.

9. The preparation method according to claim 8, characterized in that: The precursor solution for preparing the first transport layer is a first precursor solution, wherein the first precursor solution includes the bipyridine derivative and a fullerene material, wherein the solution concentration of the fullerene material is 15 mg / mL to 25 mg / mL, and the molar concentration of the bipyridine derivative is 3×10 -3 mmol / mL~7×10 -3 mmol / mL.

10. The preparation method according to claim 8, characterized in that: The precursor solution for preparing the second transport layer is a second precursor solution, and the second precursor solution includes the bipyridine derivative, wherein the concentration of the bipyridine derivative is 10 mg / mL to 20 mg / mL.

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