A novel perovskite solar cell structure based on phosphorene / graphene-sam

Abstract

The application belongs to the technical field of solar cells, and particularly relates to a novel perovskite solar cell structure based on phosphorene / graphene structure. In order to solve the problems of low charge transport efficiency, serious interface non-radiative recombination and insufficient long-term stability in the traditional perovskite solar cell, the application provides a novel perovskite solar cell structure with complete charge separation, excellent interface compatibility and excellent long-term stability. The cell structure is sequentially composed of a conductive substrate, a phosphorene / graphene layer, a first self-assembled SAM molecular layer, a perovskite light absorption layer, a second self-assembled SAM molecular layer, a phosphorene / graphene layer and an electrode from bottom to top. The phosphorene / graphene layer is combined into a high-conductivity network through covalent bonds, and the self-assembled SAM molecular layer optimizes the energy level matching by modifying the interface through chemical bonds, so as to realize efficient charge transport and suppress interface recombination, thereby synergistically improving the photoelectric conversion efficiency and working stability of the cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a novel perovskite solar cell structure based on phosphorene / graphene. Background Technology

[0002] Perovskite solar cells have become a research hotspot in the new energy field due to their advantages such as high photoelectric conversion efficiency, low manufacturing cost, and flexible wearability. However, existing perovskite solar cells still face many technical bottlenecks: poor interfacial compatibility between the charge transport layer and the perovskite absorber layer leads to severe charge recombination; in current technologies, two-dimensional materials such as graphene and rare earth materials are often used to improve their performance. While these materials perform well in some aspects, they often struggle to simultaneously address multiple key factors such as energy level matching, interface passivation, and environmental stability. For example, the high conductivity and stability of graphene are used for interface modification, but as a zero-bandgap half-metal, graphene's energy level matching with perovskite is not optimal, resulting in significant interfacial voltage loss. Two-dimensional rare earth materials such as (R3HQ)4CeRb(NO3)8 possess unique and tunable optical properties, but due to their chemical reactivity, when thinned to two dimensions, their extremely high specific surface area makes them susceptible to oxidation or hydrolysis, leading to rapid performance degradation. In addition, the inherent chemical instability of perovskite materials and their high sensitivity to moisture and oxygen result in poor long-term cycle performance of the cells. These problems severely limit the commercial application of perovskite solar cells, thus necessitating the development of a novel cell structure that combines high charge transport efficiency with excellent stability. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a novel perovskite solar cell structure based on phosphorene / graphene. By introducing a highly conductive phosphorene / graphene composite layer and an interface-engineered self-assembled SAM molecular layer, the charge separation and transport dynamics are synergistically optimized, and the structural stability and environmental tolerance of the cell are significantly improved.

[0004] The technical solution of the present invention is as follows: A novel perovskite solar cell structure based on phosphorene / graphene comprises, from bottom to top, a conductive substrate, a phosphorene / graphene layer, a first self-assembled SAM molecular layer, a perovskite light-absorbing layer, a second self-assembled SAM molecular layer, a phosphorene / graphene layer, and an electrode.

[0005] The conductive substrate serves as a mechanical support and a bottom conductive path. It is made of fluorine-doped tin oxide conductive glass, indium tin oxide conductive glass, or a flexible transparent conductive film with good conductivity and light transmittance. Its sheet resistance is controlled below 15 Ω / □ to minimize charge transfer loss.

[0006] The phosphorene / graphene layer is a key charge transport enhancement layer. Phosphorene nanosheets have ultra-high carrier mobility, while graphene has excellent electrical conductivity and mechanical strength. The two are covalently bonded together with a coupling agent to form an interwoven two-dimensional conductive network. The optimal conductivity can be achieved by controlling the mass ratio of phosphorene to graphene in the range of 1:2 to 1:5. The thickness of the composite layer is 5 to 200 nm, which can effectively reduce light absorption loss while ensuring the integrity of the charge transport channel.

[0007] The first and second self-assembled SAM molecular layers serve as electron transport and hole transport interface modification layers, respectively. The first self-assembled SAM molecular layer uses small organic molecules containing phosphate or carboxyl groups, which are chemically bonded to the phosphorene / graphene layer and form close contact with the perovskite light-absorbing layer above, effectively reducing the interface electron transport barrier. The second self-assembled SAM molecular layer uses small organic molecules containing amino or thiol groups, which effectively regulate the energy level structure of the perovskite surface, promote hole extraction, and inhibit non-radiative recombination at the interface. The thickness of both self-assembled SAM layers is 1~5 nm to avoid affecting charge transport due to excessive thickness.

[0008] The perovskite light-absorbing layer uses any ABX3 type ternary perovskite system. The light absorption range and structural stability are optimized through component control. A layer thickness of 300–600 nm achieves effective absorption across the entire spectrum. This layer is prepared using solution spin-coating or vapor deposition, offering the advantages of simple processing and low cost.

[0009] The electrode serves as the top charge collection terminal of the battery. Depending on the specific application, a highly conductive metal electrode (Au, Ag, Cu) or a transparent conductive electrode (ITO, AZO) suitable for tandem cells or transparent photovoltaic devices can be selected. The electrode thickness is precisely controlled according to the type of material used to ensure charge collection efficiency and structural stability.

[0010] Furthermore, to improve the continuity of interfacial charge transport and reduce recombination loss, an ultrathin metal oxide buffer layer (TiO2, SnO2, NiO) is added between the perovskite light-absorbing layer and the second self-assembled SAM molecular layer. x By controlling the thickness to 5~20nm, perovskite surface defects can be effectively passivated, while simultaneously constructing a gradient energy level structure to accelerate charge separation and extraction.

[0011] Beneficial effects This invention uses a phosphorene / graphene composite layer as a charge transport enhancement layer, combined with the interface modification function of the self-assembled SAM molecular layer, to significantly reduce the charge transport barrier and suppress non-radiative recombination at the interface, thereby improving the photoelectric conversion efficiency of the device by more than 15% compared with the traditional perovskite solar cell structure.

[0012] The self-assembled SAM molecular layer can form a dense protective film on the perovskite surface, effectively blocking the penetration of moisture and oxygen; at the same time, the phosphorene / graphene composite layer provides mechanical support to enhance the structural stability of the device, and the battery can still maintain an initial efficiency of no less than 85% after 1000 consecutive cycles.

[0013] Each functional layer in this battery structure is prepared using a low-temperature process (maximum temperature ≤150 ℃), which has good compatibility with flexible substrates. The selected materials are low-cost and the preparation process is simple, making it feasible and economical for large-scale production.

[0014] By adjusting the functional group types of the SAM molecular layer and controlling the composition of the perovskite material, this structure can be flexibly adapted to the needs of different application scenarios, combining high efficiency and high stability. It is suitable for multiple fields such as photovoltaic power plants, flexible electronic devices, and building-integrated photovoltaics. Attached Figure Description Figure 1 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0016] Example 1: Conductive substrate pretreatment: Fluorine-doped tin oxide (FTO) conductive glass with a sheet resistance of less than 15 Ω / □ was selected and ultrasonically cleaned with deionized water, ethanol and acetone for 30 min in sequence. After being dried with nitrogen, it was annealed at 500 ℃ for 30 min to remove surface organic contaminants and impurities.

[0017] Preparation of phosphorene / graphene layer: Phosphorene nanosheet dispersion and graphene dispersion were mixed at a mass ratio of 1:3. 1 wt% silane coupling agent was added and ultrasonically treated for 2 h to achieve uniform dispersion. Then, the mixture was spin-coated at 3000 rpm for 30 s onto the pretreated FTO substrate and annealed at 120 ℃ for 40 min to form a 100 nm thick phosphorene / graphene composite layer.

[0018] Preparation of the first self-assembled SAM molecular layer: The substrate with the above-deposited phosphorene / graphene composite layer was immersed in an ethanol solution of 0.05 mol / L trimethyl phosphate and allowed to stand at room temperature for 18 h. After removal, the surface solution was dried with nitrogen and annealed at 90 °C for 15 min to form a 2 nm thick electron transport type SAM layer.

[0019] Preparation of perovskite light-absorbing layer: Preparation of Cs 0.1 FA 0.6 MA 0.3 PbI 2.7 Br 0.3The perovskite precursor solution was spin-coated onto the first self-assembled SAM molecular layer (4000 rpm, 40 s), followed by annealing at 100 °C for 60 min to form a perovskite layer with a thickness of 450 nm.

[0020] Buffer layer preparation: A SnO2 thin film with a thickness of 10 nm was deposited on the surface of the perovskite layer as a buffer layer using atomic layer deposition.

[0021] Second self-assembled SAM molecular layer: The above sample was immersed in an ethanol solution of 0.03 mol / L aminobenzylthiophenol, left to stand at room temperature for 20 h, removed and dried with nitrogen gas and annealed at 80 ℃ for 12 min to form a 3 nm thick hole transport type SAM layer.

[0022] Phosphorene / graphene layer and electrode preparation: Repeat step 2 to prepare an 80 nm thick phosphorene / graphene layer on the second self-assembled SAM molecular layer, and then deposit an 80 nm thick Au electrode under vacuum conditions by thermal evaporation to complete the preparation and assembly of the battery device.

[0023] Example 2: The difference from Example 1 is that: in this example, a flexible transparent conductive film is used as the conductive substrate, the perovskite absorber layer is prepared by vapor deposition (thickness 350 nm), and the electrode is an AZO transparent conductive electrode with a thickness of 150 nm. The other materials, ratios and parameters are the same as in Example 1. The flexible battery prepared retains a photoelectric conversion efficiency of ≥90% after 100 cycles of bending.

[0024] The scope of protection of this invention is not limited to the specific embodiments disclosed in the above examples. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this invention should be included within the scope of the claims of this invention.

Claims

1. A novel perovskite solar cell structure based on phosphorene / graphene-SAM, characterized in that, From bottom to top, the structure comprises: a conductive substrate, a phosphorus / graphene layer, a first self-assembled SAM molecular layer, a perovskite light-absorbing layer, a second self-assembled SAM molecular layer, the phosphorus / graphene layer again, and an electrode. The phosphorus / graphene layer is a two-dimensional highly conductive network formed by covalently bonding phosphorus nanosheets and graphene. The first and second self-assembled SAM molecular layers are films formed by the self-assembly of small organic molecules with functional groups.

2. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, The conductive substrate is fluorine-doped tin oxide conductive glass, indium tin oxide conductive glass, or a flexible transparent conductive film, with a sheet resistance ≤15Ω / □.

3. The novel perovskite solar cell structure based on phosphorus / graphene according to claim 1, characterized in that, The mass ratio of phosphorus nanosheets to graphene in the phosphorus / graphene layer is 1:2 to 1:5; the thickness of the phosphorus nanosheets is 1 to 5 nm; the graphene is a single layer or few layers; and the thickness of the phosphorus / graphene layer is 50 to 200 nm.

4. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, The first self-assembled SAM molecular layer is an electron transport type modification layer, prepared using small organic molecules containing phosphate groups or carboxyl groups; the second self-assembled SAM molecular layer is a hole transport type modification layer, prepared using small organic molecules containing amino or thiol groups, and the thickness of both self-assembled SAM molecular layers is 1~5 nm.

5. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, The chemical formula of the perovskite absorber layer is Cs. x FA y MA 1-x-y PbI 3-z Br z (0≤x≤1, 0≤y≤1, x+y≤1, z≤3), with a thickness of 300~600 nm, prepared by solution spin coating or vapor deposition.

6. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, The preparation method of the phosphorene / graphene layer includes: mixing phosphorene nanosheets and graphene dispersion in a certain proportion, adding a coupling agent and ultrasonically treating for 1-3 h, then depositing them on the corresponding substrate by spin coating or spraying, and annealing at 100-150 °C for 30-60 min to form a covalent composite layer.

7. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 4, characterized in that, The electron transport type SAM molecule is trimethyl phosphate, dodecane 1-phosphate, or carboxybenzimidazole; the hole transport type SAM molecule is aminobenzylthiophenol, mercaptopyridine, or ethylenediamine silane.

8. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, The electrode is a metal electrode or a transparent conductive electrode; the metal electrode is Au, Ag or Cu, and its film thickness is 50~100 nm; the transparent conductive electrode is indium tin oxide or aluminum-doped zinc oxide thin film, and its film thickness is 100~200 nm.

9. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, The first self-assembled SAM molecular layer was prepared by immersion method: the conductive substrate with the deposited phosphorene / graphene layer was immersed in 0.01~0.1 mol / L SAM molecular ethanol solution, and left to stand at room temperature for 12~24 h. After being taken out, it was dried with nitrogen and annealed at 80~100℃ for 10~20 min.

10. The novel perovskite solar cell structure based on phosphorene / graphene according to claim 1, characterized in that, An ultrathin metal oxide buffer layer is further disposed between the perovskite light-absorbing layer and the second self-assembled SAM molecular layer. The buffer layer material is TiO2, SnO2, or NiO. x The thickness is 5~20 nm.

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