A perovskite battery and its preparation method

Abstract

The present application provides a perovskite cell and a method for preparing the same. The perovskite cell comprises an anti-reflection layer, a photoelectric conversion efficiency enhancement layer, an electron transport layer, a perovskite layer, a hole transport layer, and a top electrode, which are sequentially stacked on a conductive substrate. The anti-reflection layer is made of a two-dimensional lithium-doped graphene layer, and the photoelectric conversion efficiency enhancement layer is a perovskite quantum dot LaFeO₃ functional film layer. Lithium-doped graphene has good electron separation ability and light transmittance, and has extremely low reflectivity for infrared and visible light; perovskite quantum dots LaFeO₃ perform well in light absorption, and the high oxidation state of iron in its structure and the perovskite structure give it a strong electron-hole separation ability. Lithium-doped graphene and perovskite quantum dots LaFeO₃ have good structural compatibility, and their combined application in perovskite cells can effectively enhance the electron transition ability and improve the photoelectric conversion efficiency of perovskite cells.

Description

Technical Field

[0001] The present application relates to the field of design and production of perovskite batteries, and specifically to a perovskite battery and a method for preparing the same. Background Art

[0002] Solar cells are thin, optoelectronic semiconductor wafers that generate electricity directly from sunlight. They convert light energy into electricity through the photoelectric or photochemical effect, offering advantages such as high reliability, long lifespan, and high conversion efficiency. Perovskite solar cells, a third-generation, innovative solar cell concept, boast relatively high photoelectric conversion efficiency, low cost, and flexible processing. They have experienced rapid development in recent years, gradually rivaling silicon cells and approaching commercialization.

[0003] Since 2009, significant progress has been made in developing solar cells based on dye-sensitized solar cell technology, using organometallic halides (CH3NH3PbX3) (X = Cl, I, Br) as dyes. Because organometallic halides have a perovskite lattice structure, this type of solar cell using organometallic halide materials as the absorption layer is called a perovskite solar cell. These organometallic halides with a perovskite crystal structure have a band gap of 4.0-4.1 eV, efficiently absorbing a broad spectrum of light from visible light to 800 nm. Furthermore, this material exhibits high carrier mobility. Currently, the photoelectric conversion efficiency of perovskite solar cells has exceeded 15% and is expected to reach over 25%.

[0004] Currently, how to improve the conversion efficiency of perovskite solar cells (PSCs) is a hot topic in current research. Existing methods for improving the conversion efficiency of perovskite cells can be roughly divided into the following categories:

[0005] 1. Component control: For example, mixed cations / halogens: such as using FA / MA / Cs mixed cations (formamidine / methylamine / cesium) or I / Br mixed halogens to optimize band gap and phase stability (such as FA0. 83 MA0. 17 Pb(I0. 83 Br0. 17 )3); Low-dimensional perovskites: introducing 2D / 3D heterostructures (such as PEA2PbI4) to improve environmental stability and reduce non-radiative recombination; and performing additive engineering to improve passivation defects.

[0006] 2. Interface engineering: including electron transport layer (ETL) optimization (such as using materials such as SnO2, TiO2 or ZnO to reduce interface barriers (such as SnO2 can be prepared at low temperature to reduce hysteresis effect)), surface modification (such as PCBM or C 60SAMs) to passivate ETL defects, hole transport layer (HTL) optimization (e.g., replacing Spiro-OMeTAD: using PTAA, CuSCN or inorganic materials such as NiO X ) to improve hole extraction efficiency) and doping to improve conductivity (such as Li-TFSI+tBP doped Spiro).

[0007] 3. Improve the process: for example, use vapor-assisted deposition to prepare the corresponding functional layer and control the annealing parameters.

[0008] 4. Optimizing light absorption management: This mainly includes introducing nanostructures (such as mesoporous TiO2 or textured substrates) to enhance light absorption, and using metal electrodes (Au / Ag) or dielectric mirrors to reflect unabsorbed light. Summary of the Invention

[0009] In order to improve the photoelectric conversion efficiency of perovskite cells, this application starts from the perspective of optimizing light absorption management, and uses special materials to add an anti-reflection layer and a photoelectric conversion efficiency enhancement layer on the basis of the original perovskite cell to provide a high-conversion-efficiency perovskite cell and its preparation method.

[0010] In one aspect, the technical solution provided in this application is implemented as a perovskite cell. The perovskite cell has a "sandwich" structure consisting of a hole transport layer, a perovskite layer, and an electron transport layer. The electron transport layer of the perovskite cell is closer to the conductive substrate, on which an anti-reflection layer and a photoelectric conversion efficiency enhancement layer are sequentially stacked, with the photoelectric conversion efficiency enhancement layer in contact with the electron transport layer. The anti-reflection layer is a two-dimensional lithium-doped graphene layer, and the photoelectric conversion efficiency enhancement layer is a LaFeO3 functional film layer containing perovskite quantum dots.

[0011] Furthermore, a top electrode is provided on the hole transport layer, and the conductive substrate serves as a bottom electrode. Preferably, the conductive substrate is a flexible conductive substrate.

[0012] Lithium-doped graphene exhibits excellent electrical conductivity and light transmittance. By regulating the electronic structure of graphene through lithium doping, it not only reduces light reflection losses but also enhances carrier transport. Lithium-doped graphene (anti-reflection layer) provides a favorable light and electron transmission channel for the LaFeO3 quantum dots (functional film) and the perovskite layer, effectively promoting carrier separation and transport during the photoelectric conversion process of perovskite cells. LaFeO3 perovskite quantum dots have a high light absorption coefficient. The high oxidation state of iron in their structure and the perovskite structure provide strong electron-hole separation during the photoelectric conversion process of the perovskite layer, effectively improving the photoelectric performance of perovskite cells.

[0013] Accordingly, another aspect of the present application provides a method for preparing a perovskite cell. The method comprises: forming an anti-reflection layer on a pre-prepared conductive substrate using a pre-prepared two-dimensional lithium-doped graphene solution; forming a photoelectric conversion efficiency enhancement film layer on the anti-reflection layer using a pre-prepared LaFeO3 perovskite quantum dot solution; and sequentially preparing a stacked electron transport layer, a perovskite layer, a hole transport layer, and a top electrode on the photoelectric conversion efficiency enhancement film layer.

[0014] Furthermore, the preparation of the two-dimensional material lithium-doped graphene solution includes: preparing a graphene precursor solution with a concentration of 0.05M-0.1M, using ethanol or water as the solvent; adding the corresponding lithium salt to the graphene precursor solution and stirring to obtain a two-dimensional material lithium-doped graphene solution with a lithium salt concentration ranging from 0.01M to 0.05M. The preparation of the LaFeO3 perovskite quantum dot solution includes: uniformly dissolving the LaFeO3 perovskite quantum dot material in N,N-dimethylformamide (DMF) to obtain a LaFeO3 perovskite quantum dot solution with a concentration of 0.1M.

[0015] Furthermore, forming the anti-reflection layer includes: uniformly coating a two-dimensional lithium-doped graphene solution on a pre-prepared conductive substrate using a spin coating technique to form the anti-reflection layer, and annealing within a first temperature range to solidify the anti-reflection layer. Forming the photoelectric conversion efficiency enhancement layer includes: depositing the LaFeO3 quantum dot solution on the anti-reflection layer using a spin coating process, and then annealing within a second temperature range to ensure the crystallinity and stability of the quantum dot film and activate the quantum dots. In some embodiments, the first temperature range is 80°C-100°C, and the second temperature range is 50°C-60°C.

[0016] The technical solution provided in this application effectively improves the photoelectric conversion efficiency of perovskite cells by adding a two-dimensional lithium-doped graphene layer as a reflective layer to conventional perovskite cells, in conjunction with the addition of a LaFeO3 functional film layer containing perovskite quantum dots. The high oxidation state of iron in the LaFeO3 perovskite quantum dot material enhances the separation of electrons and holes. The lithium-doped graphene layer then provides a smooth electron transport channel for rapid separation of electrons and holes, reducing hole-electron recombination and significantly improving the photoelectric conversion efficiency of the perovskite cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 This is a schematic structural diagram of the perovskite cell provided in this application in one embodiment.

[0019] Figure 2 The present application provides a flowchart of a method for preparing a perovskite cell in one embodiment. DETAILED DESCRIPTION

[0020] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] like Figure 1 As shown, the perovskite cell 10 provided in the present application includes, from bottom to top, a conductive substrate 1, an anti-reflection layer 2, a photoelectric conversion efficiency enhancement layer 3, an electron transport layer 4, a perovskite layer 5, a hole transport layer 6, and a top electrode 7. Compared with existing perovskite cells, the above-mentioned perovskite cell 10 provided in the present application adds an anti-reflection layer 2 and a photoelectric conversion efficiency enhancement layer 3. The anti-reflection layer 2 is a two-dimensional material lithium-doped graphene layer, and the photoelectric conversion efficiency enhancement layer 3 is a perovskite quantum dot LaFeO3 functional film layer. The conductive substrate 1 also serves as the bottom electrode of the perovskite cell 10. Preferably, the conductive substrate is a flexible conductive substrate.

[0022] The two-dimensional material lithium-doped graphene adjusts the surface chemical properties of graphene and optimizes its electronic structure by doping lithium atoms, so that it exhibits lower reflectivity in the infrared and visible spectra. The perovskite cell 10 provides the use of two-dimensional material lithium-doped graphene to make the anti-reflection layer 2, which can not only reduce the reflection loss of incident light and improve the light absorption rate, but also provide a good transmission channel for electrons to be transmitted to the bottom electrode. The high oxidation state of iron in the perovskite quantum dot LaFeO3 material improves the separation ability of electrons and holes in the perovskite cell, and the perovskite structure is also conducive to the transmission of electrons. The synergistic effect of perovskite quantum dot LaFeO3 and lithium-doped graphene can not only enhance the photoelectric conversion efficiency of the perovskite cell, but also ensure the stability and durability of the perovskite cell. Other perovskite quantum dot materials perform poorly in terms of photoelectric conversion efficiency or stability, and cannot match the charge transmission ability of lithium-doped graphene well.

[0023] Corresponding to the above-mentioned perovskite battery, another aspect of the present application also provides a method for preparing a perovskite battery. Figure 2 In the embodiment shown, the above preparation method includes the following steps:

[0024] S1. Prepare a conductive substrate. As the foundation for the photovoltaic cell, the conductive substrate must ensure structural stability and good light transmittance. The conductive substrate can be made of conductive glass or other flexible materials such as PET.

[0025] S2. Prepare the solutions required for depositing the electron transport layer, perovskite layer, and hole transport layer. In some embodiments, the hole transport layer (HTL) material is a Spiro-OMeTAD or PEDOT:PSS solution to ensure efficient hole transport from the perovskite layer to the top electrode. Optionally, the HTL solution has a concentration of 0.1M to 0.2M, and the solvent is chlorobenzene or n-butanol. The perovskite layer material is MAPbI3 or a mixed halide perovskite (as a light absorbing layer), and a perovskite precursor solution is prepared using a solution method. Optionally, the perovskite precursor solution has a concentration of 0.3M, and the solvent is a mixed solution of N,N-dimethylformamide (DMF) and dichlorobenzene (DCB). The electron transport layer (ETL) material can be selected from TiO2, SnO2 or ZnO to promote the efficient conduction of electrons from the light absorption layer to the bottom electrode and avoid the recombination of electrons and holes. It is also prepared in the form of a solution; optionally, the concentration of the electron transport layer solution is 0.1M - 0.2M, using ethanol or acetone as the solvent.

[0026] S3. Prepare a lithium-doped graphene solution and a perovskite quantum dot LaFeO3 solution. The preparation of the two-dimensional material lithium-doped graphene solution may specifically include: preparing a graphene precursor solution with a concentration of 0.05M to 0.1M, using ethanol or water as the solvent; adding a corresponding lithium salt (such as LiCl, LiF, etc.) to the graphene precursor solution and stirring to obtain a two-dimensional material lithium-doped graphene solution with a lithium salt concentration in the range of 0.01M to 0.05M.

[0027] The LaFeO3 perovskite quantum dot solution can be prepared in the following manner: the LaFeO3 perovskite quantum dot material is uniformly dissolved in N,N-dimethylformamide (DMF) to obtain a LaFeO3 perovskite quantum dot solution with a concentration of 0.1M.

[0028] S4. Deposit an anti-reflection layer on a conductive substrate using the prepared lithium-doped graphene solution.

[0029] The anti-reflection layer can be deposited using a conventional spin coating-annealing technique, uniformly coating the lithium-doped graphene solution onto the flexible substrate. Preferably, the spin coating speed is set at 2000-3000 rpm to ensure a uniform film thickness (typically 10nm-30nm). The film is then annealed at 80°C-100°C for a predetermined time to solidify the film and enhance its adhesion and stability.

[0030] S5. Deposit a photoelectric conversion efficiency enhancement layer onto the anti-reflection layer using the prepared LaFeO3 perovskite quantum dot solution. The LaFeO3 quantum dot solution is also deposited onto the anti-reflection layer using a spin coating-annealing process to form the photoelectric conversion efficiency enhancement layer. Preferably, the spin coating speed is set to 1500 rpm, and the annealing temperature is set between 50°C and 60°C to ensure the crystallinity and stability of the quantum dot film (typically maintaining a thickness of 20nm to 50nm) while activating the quantum dots.

[0031] S6. Using the relevant solutions prepared in step S2, respectively, a "sandwich" structure consisting of an electron transport layer, a perovskite layer, and a hole transport layer is deposited on the photoelectric conversion efficiency enhancing layer.

[0032] Specifically, the electron transport material used for depositing the electron transport layer (ETL) can be a TiO2, SnO2, or ZnO solution to promote efficient electron conduction from the light absorption layer (perovskite layer) to the bottom electrode, preventing electron-hole recombination. Preferably, the concentration of the electron transport material solution is set to 0.1M-0.2M, and the solvent is ethanol or acetone. When depositing the ETL, the spin coating speed can be set to 3000 rpm to obtain a uniform ETL with appropriate thickness. The corresponding annealing temperature is set to 150°C-200°C to promote crystallization of the ETL, improving its conductivity and stability.

[0033] For the light-absorbing layer (perovskite layer), a solution of MAPbI3 or a mixed halide perovskite can be used as the perovskite precursor solution. Optionally, the precursor solution concentration is 0.3 M to ensure a uniform and dense perovskite layer after deposition. The solvent is a mixture of N,N-dimethylformamide (DMF) and dichlorobenzene (DCB). Correspondingly, when depositing the perovskite layer, the spin coating speed can be set to 3000-4000 rpm to achieve a film with good uniformity and appropriate thickness, and the annealing temperature is set to 100°C-120°C. The annealing process of the deposited perovskite layer promotes the formation of perovskite crystals, improving the crystallinity and optoelectronic properties of the film.

[0034] For hole transport layer (HTL) preparation: The HTL ensures efficient hole transport from the light-absorbing layer to the top electrode. Typically, the HTL material is a 0.1M-0.2M solution of Spiro-OMeTAD or PEDOT:PSS, prepared using chlorobenzene or n-butanol as the solvent. Accordingly, the HTL is deposited at a spin-coating speed of 2000 rpm and an annealing temperature of 60°C-80°C to promote thin film formation and enhance its conductivity.

[0035] The thickness of each film layer of the above "sandwich" structure is usually between tens and hundreds of nanometers, and can be selected by those skilled in the art according to actual needs. No further explanation will be given here.

[0036] S7. Prepare a top electrode on the hole transport layer. The top electrode, along with the bottom electrode (conductive substrate), is used to conduct the battery's charge outward. It can be made of silver, copper, or other conductive metals or alloys.

[0037] The technical solution provided in this application effectively reduces light reflectivity and increases light transmittance by introducing a lithium-doped graphene anti-reflection layer onto the traditional perovskite cell structure, thereby improving the perovskite cell's ability to absorb light. While reducing light reflection losses, the insertion of LaFeO3 perovskite quantum dots can significantly improve photoelectric conversion efficiency. The synergistic effect of this dual-coating structure can effectively enhance the perovskite cell's light absorption capacity, optimize the extraction of electrons and holes, and reduce non-radiative recombination, significantly improving the perovskite cell's photoelectric conversion efficiency (the photoelectric conversion efficiency of a traditional perovskite cell is approximately 19.8%, while the introduction of a lithium-doped graphene layer + LaFeO3 perovskite quantum dot layer can reach over 23.2%).

[0038] The above description is merely an embodiment of the present application and is not intended to limit the present application. Those skilled in the art will appreciate that the technical solutions provided herein are susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A perovskite cell having a "sandwich" structure of a hole transport layer, a perovskite layer, and an electron transport layer; characterized in that: The electron transport layer of the perovskite battery is closer to the conductive substrate, and an anti-reflection layer and a photoelectric conversion efficiency enhancement layer are stacked in sequence on the conductive substrate, and the photoelectric conversion efficiency enhancement layer is in contact with the electron transport layer; the anti-reflection layer is a two-dimensional material lithium-doped graphene layer, and the photoelectric conversion efficiency enhancement layer is a perovskite quantum dot LaFeO3 functional film layer.

2. The perovskite battery according to claim 1, wherein The conductive substrate is a flexible conductive substrate.

3. The perovskite battery according to claim 1 or 2, wherein: A top electrode is also provided on the hole transport layer.

4. A method for preparing a perovskite battery, characterized in that: The preparation method includes: using a pre-prepared two-dimensional material lithium-doped graphene solution to form an anti-reflection layer on a pre-prepared conductive substrate; using a pre-prepared LaFeO3 perovskite quantum dot solution to form a photoelectric conversion efficiency enhancement layer on the anti-reflection layer; and sequentially preparing a stacked electron transport layer, a perovskite layer, a hole transport layer and a top electrode on the photoelectric conversion efficiency enhancement layer.

5. The preparation method according to claim 4, wherein The preparation of the two-dimensional material lithium-doped graphene solution includes: preparing a graphene precursor solution with a concentration of 0.05M-0.1M, with ethanol or water as the solvent; adding corresponding lithium salts to the graphene precursor solution and stirring to obtain a two-dimensional material lithium-doped graphene solution with a lithium salt concentration range of 0.01M-0.05M.

6. The preparation method according to claim 4, wherein The preparation of the LaFeO3 perovskite quantum dot solution includes: uniformly dissolving the LaFeO3 perovskite quantum dot material in N,N-dimethylformamide (DMF) to obtain a LaFeO3 perovskite quantum dot solution with a concentration of 0.1M.

7. The preparation method according to any one of claims 4 to 6, characterized in that The forming of the anti-reflection layer comprises: using a spin coating technique to uniformly coat a two-dimensional material lithium-doped graphene solution on a pre-prepared conductive substrate to form the anti-reflection layer, and annealing within a first temperature range to solidify the anti-reflection layer.

8. The preparation method according to any one of claims 4 to 6, characterized in that The forming of the photoelectric conversion efficiency enhancement layer includes: depositing the LaFeO3 perovskite quantum dot solution on the anti-reflection layer using a spin coating process, and then annealing within a second temperature range to ensure the crystallinity and stability of the quantum dot film and activate the quantum dots.

9. The preparation method according to claim 7, characterized in that The first temperature range is 80°C-100°C.

10. The preparation method according to claim 8, characterized in that The second temperature range is 50°C-60°C.

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