An inorganic perovskite solar cell doped with a carboxylic anhydride group-containing additive and a preparation method thereof

Abstract

The application discloses an inorganic perovskite solar cell doped with a carboxylic anhydride group-containing additive and a preparation method thereof, and relates to the technical field of solar cells. The battery is sequentially stacked from bottom to top with a conductive transparent substrate, an electron transport layer, an inorganic perovskite light-absorbing layer, a hole transport layer and a top electrode, and the material of the inorganic perovskite light-absorbing layer comprises an inorganic perovskite and a carboxylic anhydride group-containing additive. By introducing a carboxylic anhydride group-containing molecule with a specific structure as an additive, the nucleation rate of the inorganic perovskite thin film can be effectively slowed down, and the ordered growth of the crystal can be promoted, so that the crystal size of the thin film is significantly increased and the grain boundary defects are reduced. The method provided by the application effectively reduces the non-radiative recombination loss, and greatly improves the photoelectric conversion efficiency and photo-thermal stability of the inorganic perovskite solar cell in an outdoor and indoor weak light environment.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more specifically, to an inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups and its preparation method. Background Technology

[0002] In recent years, with the continuous rise in global energy demand and the rapid development of renewable energy technologies, high-efficiency and low-cost solar cells have become a cutting-edge research field. Among them, perovskite solar cells have emerged as a promising candidate due to their excellent optical and electrical properties (such as high light absorption coefficient, tunable bandgap, long carrier diffusion length, and low exciton binding energy). Currently, the peak efficiency of single-junction perovskite solar cells has reached over 27.0%, and their performance is fully comparable to that of commercially available silicon-based solar cells.

[0003] However, existing traditional organic-inorganic hybrid perovskites (such as MAPbI3 and FAPbI3) suffer from poor photothermal stability under light and heat conditions due to the presence of volatile organic cations within the material, which greatly restricts their commercialization and industrialization. Therefore, solving the photothermal stability problem of perovskite solar cells has become a major challenge that urgently needs to be addressed in this field. Numerous studies and existing technologies have shown that all-inorganic perovskites formed by replacing organic cations with inorganic ions exhibit excellent photothermal stability and are widely considered an effective way to solve the stability problem of perovskite solar cells. This is mainly based on two reasons: firstly, the main role of organic cations is to stabilize the perovskite crystal structure and adjust the lattice parameters, while having no decisive influence on the band structure; secondly, the bond energy of inorganic ionic bonds (such as Cs-I bonds) is much higher than that of hydrogen bonds (such as HI bonds) in traditional organic-inorganic hybrid perovskite materials. Among numerous all-inorganic perovskite materials, CsPbI2Br stands out due to its optimal band gap (approximately 1.91 eV), achieving an ideal balance between light absorption and photothermal stability, and demonstrating great potential application value in tandem solar cells and semi-transparent photovoltaic devices.

[0004] As the core functional layer of photovoltaic cells, the quality of inorganic perovskite (such as CsPbI₂Br) thin films directly determines the overall photoelectric performance of the device. However, in existing conventional fabrication processes, the film quality of inorganic perovskite films often falls short of ideal standards. In current technologies for coating and annealing inorganic perovskite films, the extremely rapid crystallization kinetics of the precursor solution during solvent evaporation makes it difficult to effectively control the nucleation rate. This uncontrolled rapid crystallization inevitably leads to smaller crystal sizes and a significantly increased number of grain boundaries in the final inorganic perovskite film. Simultaneously, a large number of defect states (such as halogen vacancies and uncoordinated lead ions) are easily generated within the film, at grain boundaries, and on the surface. These abundant defect states readily act as non-radiative recombination centers, severely reducing carrier lifetime, causing significant open-circuit voltage (Voc) losses, and lowering overall photoelectric conversion efficiency. They also become channels for water and oxygen intrusion and ion migration, further deteriorating the long-term operational stability of the device.

[0005] In summary, there is an urgent need for an inorganic perovskite thin film preparation process and its application that can effectively control the nucleation and crystallization process of inorganic perovskite thin films and reduce the density of grain boundary and surface defect states, in order to improve the quality of the thin films while achieving inorganic perovskite solar cells with both high photoelectric conversion efficiency and excellent stability. Summary of the Invention

[0006] One of the technical problems to be solved by the present invention is to provide an inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups, so as to solve the problems of excessively fast crystallization rate of inorganic perovskite thin films in existing preparation methods, which leads to a large number of defect states and severe non-radiative recombination.

[0007] To overcome the shortcomings of the prior art, the present invention provides an inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups, comprising a conductive transparent substrate, an electron transport layer, an inorganic perovskite light-absorbing layer, a hole transport layer, and a top electrode stacked sequentially from bottom to top. The material of the inorganic perovskite light-absorbing layer includes inorganic perovskite and additives containing carboxylic anhydride groups; the additives containing carboxylic anhydride groups are one or more of 3,4-thiophene dicarboxylic anhydride, 2,3-pyridine dicarboxylic anhydride, and 2,3-pyrazine dicarboxylic anhydride.

[0008] This invention provides an inorganic perovskite solar cell doped with carboxylic anhydride groups, which, compared to existing technologies, has the following advantages: This invention introduces 3,4-thiophene dicarboxylic anhydride, 2,3-pyridine dicarboxylic anhydride, or 2,3-pyrazine dicarboxylic anhydride molecules into the inorganic perovskite light-absorbing layer. Due to the excellent coordination ability of the unique carboxylic anhydride groups in the molecular structure, they can generate strong chemical interactions with lead halide in the inorganic perovskite precursor, thereby participating in the coordination competition between the precursor and solvent during the film formation stage. This enhances the nucleation barrier of the perovskite crystal and slows down the originally extremely fast crystallization kinetics. The aforementioned moderately delayed nucleation process is beneficial for the inorganic perovskite crystal… Ordered growth provides ample conditions for the final cured film to exhibit significantly increased crystal size and higher crystallinity, thereby reducing the number of grain boundaries. Furthermore, the carboxylic anhydride-containing molecules present at the grain boundaries and surface of the film can passivate uncoordinated lead ions and other defect sites in situ, reducing the defect state density inside the film and at the interface. The large grain morphology and defect passivation effect together suppress nonradiative recombination pathways inside the device, reducing carrier losses during transport, and thus significantly improving the open-circuit voltage of the inorganic perovskite solar cell. This allows it to exhibit good photoelectric conversion efficiency and excellent stability under both outdoor standard illumination and indoor low-light conditions.

[0009] In one possible implementation, the inorganic perovskite has the chemical formula ABX3; Where A is Cs + 、Rb + One or two of them; B is Pb 2+ Sn 2+ One or two of them; X is Cl - ,Br - I - One or more of them.

[0010] Compared with existing technologies, this embodiment uses inorganic metal cations to replace the volatile organic cations in traditional organic-inorganic hybrid perovskites, eliminating the organic components inside the material that are easily decomposed and volatilized by heat. The chemical bond energy formed between inorganic ions is much higher than the hydrogen bond force in hybrid materials, giving the perovskite lattice superior thermal and light stability. Furthermore, by introducing inorganic ions and halide anions with different radii and energy levels at the A, B, and X sites, the lattice parameters and band structure of the inorganic perovskite material can be effectively adjusted, ensuring the stability of the crystal structure while meeting the customized bandgap requirements of different photovoltaic devices.

[0011] In one possible implementation, the inorganic perovskite is CsPbI2Br.

[0012] Compared to existing technologies, the CsPbI₂Br material used in this embodiment achieves an excellent balance between light absorption range and inherent photothermal stability due to its suitable bandgap of approximately 1.91 eV. Compared to CsPbI₃, which is prone to phase transition and instability in atmospheric environments, and CsPbIBr₂ or CsPbBr₃, whose excessively large bandgap severely limits light collection capabilities, the all-inorganic CsPbI₂Br not only maintains phase structure stability under normal atmospheric conditions but also provides ample photogenerated carriers. This bandgap characteristic makes it exhibit outstanding application potential in the construction of tandem solar cells and semi-transparent photovoltaic devices.

[0013] In one possible implementation, the conductive transparent substrate is one of a polymer substrate, indium tin oxide conductive glass, or fluorine-doped tin dioxide conductive glass; The electron transport layer is made of one of the following materials: TiO2, SnO2, ZnO, Zn2SnO4, BaTiO3, SrTiO3, MgTiO3, and BaSnO3. The hole transport layer is made of one of poly(3-hexylthiophene) or 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene; The material of the top electrode is one of gold, silver, or conductive carbon.

[0014] Compared with existing technologies, this embodiment provides a variety of different material combinations: the polymer substrate, indium tin oxide conductive glass, or fluorine-doped tin dioxide conductive glass have both high transmittance and excellent conductivity, which can ensure that sufficient sunlight passes through and reaches the light-absorbing layer, while achieving efficient collection of charge carriers on the substrate side; the electron transport layer composed of inorganic metal oxides has high electron mobility and chemical stability, and its conduction band energy level is well aligned with the inorganic perovskite light-absorbing layer, which promotes the rapid extraction of photogenerated electrons and effectively blocks hole backflow; the hole transport layer of poly-3-hexylthiophene or spirodifluorene has a matching valence band energy level, which can efficiently extract and transport photogenerated holes, and its good film-forming properties are beneficial to providing protection for the surface of the underlying light-absorbing layer. Gold, silver, or conductive carbon materials are used as the top electrode, providing stable work function matching and low contact resistance. The combination of the above-mentioned materials constructs a gradient-smooth charge transport energy level network inside the device. Combined with the large-grain flat perovskite surface formed after additive regulation, a tight and low-defect interlayer contact interface is constructed, which reduces charge accumulation and non-radiative recombination loss at the interface, ensuring the high fill factor and overall output efficiency of the battery.

[0015] Another technical problem to be solved by the present invention is to provide a method for preparing inorganic perovskite solar cells doped with additives containing carboxylic anhydride groups, so as to solve the problem that the excessively fast nucleation and crystallization rate of inorganic perovskite thin films in the existing preparation methods leads to poor film quality and high defect density.

[0016] To overcome the shortcomings of the prior art, the present invention provides a method for preparing an inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups, comprising the following steps: S1: The conductive transparent substrate is cleaned and then subjected to ultraviolet ozone treatment; S2: Coat the conductive transparent substrate after step S1 with an electron transport layer solution, and then anneal the substrate to obtain the electron transport layer. S3: Coat the electron transport layer obtained in step S2 with an inorganic perovskite precursor solution containing carboxylic anhydride group additives, and obtain the inorganic perovskite light-absorbing layer by gradient annealing. S4: Coat the inorganic perovskite light-absorbing layer obtained in step S3 with a hole transport layer solution to obtain the hole transport layer; S5: The top electrode is obtained by vapor deposition of metal material on the hole transport layer obtained in step S4.

[0017] Compared with existing technologies, the preparation method of inorganic perovskite solar cells doped with carboxylic anhydride-based additives of the present invention has the following advantages: The preparation method of the present invention replaces the conventional pure inorganic perovskite precursor coating process with precursor coating containing carboxylic anhydride-based additives combined with gradient annealing. The ultraviolet ozone treatment of the conductive substrate removes surface organic residues and improves wettability, laying the interfacial foundation for uniform coating of each functional layer. In the core light-absorbing layer preparation stage, the carboxylic anhydride-based molecules in the precursor liquid undergo coordination interactions with metal cations during solvent evaporation, raising the nucleation barrier of the system. Combined with the gradient annealing treatment in step S3, it provides mild thermodynamic transition conditions for stable solvent evaporation and coordination competition, avoiding the chaotic rapid nucleation caused by sudden high-temperature cooling. The preparation method of this invention combines chemical additives with thermodynamic gradient heating to provide sufficient ordered growth period for inorganic perovskite crystals, increasing the grain size of the thin film, reducing the number of grain boundaries, and achieving in-situ passivation of defects at grain boundaries and surfaces. Furthermore, the bottom electron transport layer and the top hole transport layer are prepared by sequential spin-coating, tightly wrapping the high-quality light-absorbing layer, reducing manufacturing costs while effectively reducing non-radiative recombination losses at the interface, thereby obtaining an inorganic perovskite solar cell device with high photoelectric conversion efficiency and excellent photothermal stability.

[0018] In one possible implementation, in step S2, the electron transport layer solution is a tin dioxide solution; The tin dioxide solution is a 2.5% solution prepared by diluting a 15% tin dioxide colloidal aqueous solution with a mixed solution of isopropanol and water.

[0019] Compared with existing technologies, in this embodiment, a mixture of isopropanol and water is used to dilute the high concentration of tin dioxide colloid, thereby adjusting the surface tension and fluid viscosity of the electron transport layer precursor solution. The addition of isopropanol reduces the surface tension of the aqueous colloidal solution, significantly improving its spreading and wetting performance on the conductive substrate treated with ultraviolet ozone, avoiding solution agglomeration or the formation of coating blind zones. This embodiment precisely controls the mass fraction of the solution at 2.5%, limiting the upper limit of the thickness of the film formed in a single coating. While ensuring that the underlying substrate is completely covered to block leakage current, it avoids the increase in self-series resistance and decrease in light transmittance caused by excessive thickness of the electron transport layer, providing a material basis for the preparation of a dense and ultrathin electron transport layer.

[0020] In one possible implementation, in step S2, the coating is performed by spin coating, with spin coating parameters of 3000 rpm / min-4000 rpm / min for 25 s-40 s. The annealing parameters are: holding at 140 ℃-160 ℃ for 30 min-40 min.

[0021] Compared with the prior art, in this embodiment, the spin coating speed of 3000-4000 rpm / min provides a suitable centrifugal force, which allows the diluted tin dioxide solution to be evenly spread and excess solvent to be spun off within 25-40 s, resulting in a uniform nanoscale wet film. The subsequent medium-temperature annealing treatment at 140-160 ℃ can promote the complete evaporation of water and isopropanol in the wet film and drive the tin dioxide nanoparticles to form a tight interconnection and network densification. This ensures that the electron transport layer has sufficient crystallinity and electron extraction mobility, while avoiding damage to the conductivity of the conductive glass substrate or unnecessary energy consumption caused by excessively high temperatures. Finally, a high-quality electron transport network with high surface flatness and few defects is obtained, providing a flat and reliable support interface for the subsequent adhesion and directional growth of large-grain inorganic perovskite layers.

[0022] In one possible implementation, step S3, the preparation process of the inorganic perovskite precursor solution containing carboxylic anhydride group additives includes: dissolving lead iodide, cesium iodide, lead bromide and the carboxylic anhydride group additives in a solvent, and stirring at 60 °C to obtain a clear and transparent mixed solution. The solvent is one or both of amide solvents and sulfone solvents; The concentration of the inorganic perovskite precursor solution containing carboxylic anhydride group additives is 0.8 M-1.5 M; The concentration of the carboxylic anhydride-containing additive in the inorganic perovskite precursor solution containing the carboxylic anhydride-containing additive is 1 mg / mL to 4 mg / mL.

[0023] Compared with existing technologies, this embodiment utilizes the high polarity and strong coordination ability of amide or sulfone solvents to fully dissolve the inorganic halide precursor and carboxylic anhydride group additives. Continuous stirring at 60 °C not only accelerates the complete dissociation of the solid solute to obtain a clear and homogeneous system, but also promotes appropriate pre-coordination between the carboxyl groups in the additive molecules and the lead-based complex. By controlling the concentration of the precursor bulk at 0.8 M-1.5 M, sufficient thickness is ensured for subsequent film formation to maximize the absorption of solar photons. At the same time, the concentration of the additive is strictly defined as 1 mg / mL-4 mg / mL, which ensures that sufficient carboxylic anhydride groups participate in regulating crystallization kinetics and passivating surface defects, while avoiding excessive aggregation of organic additives inside the film that would hinder charge transport between grains. This lays the compositional foundation for the preparation of high-quality inorganic perovskite wet films.

[0024] In one possible implementation, in step S3, the coating is performed by spin coating with the following parameters: running at a speed of 900 rpm / min-1100 rpm / min for 10 s-15 s, followed by running at a speed of 1900 rpm / min-2100 rpm / min for 110 s-130 s. The parameters for the gradient annealing process are as follows: first, maintain the temperature at 45 ℃-60 ℃ for 2 min-4 min, and then maintain the temperature at 150 ℃-180 ℃ for 5 min-15 min.

[0025] Compared with existing technologies, this embodiment utilizes a stepped spin-coating process combining low and high speeds to uniformly spread a precursor solution with a certain viscosity on the substrate surface. Then, under high centrifugal force, excess solvent is rapidly ejected, achieving a uniform supersaturated state and forming a smooth wet film of consistent thickness. Combined with gradient annealing, some residual solvent is removed under mild conditions of 45℃-60℃, allowing intermediate complexes to slowly decompose and form uniformly distributed crystal nuclei, avoiding film-forming pores or disordered nucleation caused by violent solvent evaporation. Subsequently, at a higher temperature of 150℃-180℃, rapid grain growth is driven, completing the phase transformation. The control of the aforementioned thermodynamic gradient, combined with the chemical coordination retardation effect of additives in the precursor, provides a ample window for ordered growth of inorganic perovskite crystals, increasing the grain boundary size of the final film and improving overall crystallinity.

[0026] In one possible implementation, in step S4, the hole transport layer solution is a poly-3-hexylthiophene solution, which uses chlorobenzene as a solvent and has a concentration of 8 mg / mL-15 mg / mL; the coating is performed by spin coating, with spin coating parameters of 3000 rpm / min-4000 rpm / min for 30 s-40 s; In step S5, the thickness of the top electrode is 60 nm-80 nm.

[0027] Compared with existing technologies, the above technical solution uses chlorobenzene as a solvent to prepare a poly-3-hexylthiophene solution, utilizing the characteristics of orthogonal solvent systems. This prevents the dissolution or damage of the bottom inorganic perovskite light-absorbing layer during spin coating. By controlling the concentration at 8 mg / mL-15 mg / mL and using a rotation speed of 3000 rpm / min-4000 rpm / min, a hole transport layer with moderate thickness and a dense surface is obtained. This effectively covers the surface of the light-absorbing layer to block electron leakage current and ensures efficient and low-resistance hole transport. In step S5, the thickness of the top electrode is limited to 60 nm-80 nm. This ensures excellent lateral conductivity of the electrode while avoiding internal mechanical stress or unnecessary fabrication costs caused by an excessively thick metal layer, thus synergistically ensuring the device's efficient charge collection circuit and overall structural stability. Attached Figure Description

[0028] Figure 1 A schematic diagram of the device structure of the inorganic perovskite solar cell provided by the present invention; Figure 2 The chemical structure diagram of the additive molecule containing carboxylic anhydride groups provided in the embodiments of the present invention is shown. Figure 3 The XRD patterns of the inorganic perovskite films prepared in Comparative Example 1 and Examples 1-3 of this invention are shown below. Figure 4 SEM images of the inorganic perovskite films prepared in Comparative Example 1 and Examples 1-3 of this invention; Figure 5 The JV test curves are shown for the inorganic perovskite solar cells prepared in Comparative Example 1 and Examples 1-3 of this invention. Figure 6 This is a schematic diagram of the device structure of the inorganic perovskite solar cell provided in Embodiment 1 of the present invention; Explanation of reference numerals in the attached figures: 1. Conductive transparent substrate; 2. Electron transport layer; 3. Inorganic perovskite light-absorbing layer; 4. Hole transport layer; 5. Top electrode. Detailed Implementation

[0029] First, those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0030] This invention provides an inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups, such as... Figure 1 As shown, it includes a conductive transparent substrate 1, an electron transport layer 2, an inorganic perovskite light-absorbing layer 3, a hole transport layer 4, and a top electrode 5, which are stacked sequentially from bottom to top. The inorganic perovskite light-absorbing layer 3 is made of inorganic perovskite and additives containing carboxylic anhydride groups; the additives containing carboxylic anhydride groups are one or more of 3,4-thiophene dicarboxylic anhydride, 2,3-pyridine dicarboxylic anhydride, and 2,3-pyrazine dicarboxylic anhydride.

[0031] As a preferred embodiment, the inorganic perovskite has the chemical formula ABX3; Where A is Cs + 、Rb + One or two of them; B is Pb 2+ Sn 2+ One or two of them; X is Cl - ,Br - I - One or more of them.

[0032] As a preferred embodiment, the inorganic perovskite is CsPbI2Br.

[0033] As a preferred embodiment, the conductive transparent substrate 1 is one of a polymer substrate, indium tin oxide conductive glass, or fluorine-doped tin dioxide conductive glass; The electron transport layer 2 is made of one of the following materials: TiO2, SnO2, ZnO, Zn2SnO4, BaTiO3, SrTiO3, MgTiO3, and BaSnO3. The hole transport layer 4 is made of one of poly(3-hexylthiophene) or 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene; The material of the top electrode 5 is one of gold, silver, or conductive carbon.

[0034] This invention provides a method for preparing an inorganic perovskite solar cell doped with an additive containing carboxylic anhydride groups, comprising the following steps: S1: The conductive transparent substrate 1 is cleaned and subjected to ultraviolet ozone treatment; S2: Coat the conductive transparent substrate 1 after step S1 with an electron transport layer 2 solution, and then anneal the electron transport layer 2 to obtain the electron transport layer 2. S3: Coat the electron transport layer 2 obtained in step S2 with an inorganic perovskite precursor solution containing carboxylic anhydride group additives, and obtain the inorganic perovskite light-absorbing layer 3 by gradient annealing. S4: Coat the inorganic perovskite light-absorbing layer 3 obtained in step S3 with a hole transport layer 4 solution to obtain the hole transport layer 4. S5: The top electrode 5 is obtained by vapor deposition of metal material on the hole transport layer 4 obtained in step S4.

[0035] As a preferred embodiment, in step S2, the electron transport layer 2 solution is a tin dioxide solution; The tin dioxide solution is a 2.5% solution prepared by diluting a 15% tin dioxide colloidal aqueous solution with a mixed solution of isopropanol and water.

[0036] As a preferred embodiment, in step S2, the coating is performed using a spin coating method, with spin coating parameters of 3000 rpm / min-4000 rpm / min for 25 s-40 s. The annealing parameters are: holding at 140 ℃-160 ℃ for 30 min-40 min.

[0037] As a preferred embodiment, in step S3, the preparation process of the inorganic perovskite precursor solution containing carboxylic anhydride group additives includes: dissolving lead iodide, cesium iodide, lead bromide and the carboxylic anhydride group additives in a solvent, and stirring at 60 °C to obtain a clear and transparent mixed solution. The solvent is one or both of amide solvents and sulfone solvents; The concentration of the inorganic perovskite precursor solution containing carboxylic anhydride group additives is 0.8 M-1.5 M; The concentration of the carboxylic anhydride-containing additive in the inorganic perovskite precursor solution containing the carboxylic anhydride-containing additive is 1 mg / mL to 4 mg / mL.

[0038] As a preferred embodiment, in step S3, the coating is performed using a spin coating method with the following spin coating parameters: running at a speed of 900 rpm / min-1100 rpm / min for 10 s-15 s, followed by running at a speed of 1900 rpm / min-2100 rpm / min for 110 s-130 s; The parameters for the gradient annealing process are as follows: first, maintain the temperature at 45 ℃-60 ℃ for 2 min-4 min, and then maintain the temperature at 150 ℃-180 ℃ for 5 min-15 min.

[0039] As a preferred embodiment, in step S4, the hole transport layer solution is a poly-3-hexylthiophene solution, the poly-3-hexylthiophene solution uses chlorobenzene as a solvent, and the concentration is 8 mg / mL-15 mg / mL; the coating is performed by spin coating, and the spin coating parameters are: running at a speed of 3000 rpm / min-4000 rpm / min for 30 s-40 s; In step S5, the thickness of the top electrode 5 is 60 nm-80 nm.

[0040] This invention is based on additive engineering containing carboxylic anhydride groups. Utilizing the strong coordination between the unique carboxylic anhydride groups in the molecule and lead halide in the precursor, these additives effectively participate in the coordination competition between the precursor and solvent, enhancing the nucleation barrier. This allows for precise control of the crystallization kinetics, resulting in inorganic perovskite films with larger grain sizes and significantly enhanced crystallinity. These additives are not only inexpensive and widely available, but also effectively passivate grain boundaries and surface defects in inorganic perovskites while optimizing film quality. This significantly reduces the defect state density within the film and suppresses non-radiative recombination losses, thereby extending carrier lifetime and synergistically improving the photoelectric conversion efficiency and operational stability of solar cells. The inorganic perovskite photovoltaic cells prepared based on this method exhibit excellent photoelectric performance under both standard outdoor illumination and low-light indoor environments, demonstrating promising commercial application prospects.

[0041] The following are embodiments incorporating specific data to further elaborate on the above-described technical solutions of the present invention: Example 1 This embodiment provides an inorganic perovskite solar cell doped with an additive containing carboxylic anhydride groups and its preparation method. The additive containing carboxylic anhydride groups in this embodiment is 3,4-thiophene dicarboxylic anhydride, and its molecular structure is as follows: Figure 2 As shown in the figure. A schematic diagram of the battery structure obtained in this embodiment is shown below. Figure 6 As shown, the layers stacked from bottom to top are ITO conductive glass, SnO2 electron transport layer, CsPbI2Br inorganic perovskite light-absorbing layer, P3HT hole transport layer, and Au top electrode. The specific fabrication process of this battery includes the following steps: S1: Clean the conductive transparent substrate and treat it with ultraviolet ozone; specifically: ultrasonically clean the 2 cm*2 cm ITO conductive glass in sequence with deionized water, ethanol, acetone and isopropanol, each cleaning for 30 min; then blow the cleaned ITO conductive glass with nitrogen and treat it with ultraviolet ozone for 15 min.

[0042] S2: An electron transport layer solution is coated onto the conductive transparent substrate treated in step S1, and the electron transport layer is obtained after annealing. Specifically, a diluted tin dioxide solution is spin-coated onto the surface of the ITO conductive glass at a spin-coating rate of 4000 rpm / min for 30 s; then annealed at 150 °C for 30 min to obtain a SnO2 electron transport layer with a thickness of approximately 30 nm. The diluted tin dioxide solution is prepared by mixing a 15% (w / w) tin dioxide colloidal solution, deionized water, and isopropanol in a volume ratio of 1:3:3.

[0043] S3: Coat the electron transport layer obtained in step S2 with an inorganic perovskite precursor solution containing carboxylic anhydride group additives, and obtain an inorganic perovskite light-absorbing layer by gradient annealing; specifically: drop a CsPbI2Br perovskite precursor solution containing 3,4-thiophene dicarboxylic anhydride additive onto the SnO2 electron transport layer, run at 1000 rpm / min for 10 s and at 2000 rpm / min for 120 s respectively to obtain a transparent perovskite wet film; then anneal the perovskite wet film at 50 ℃ for 2 min, and then anneal at 160 ℃ for 10 min to obtain a CsPbI2Br active layer film (i.e., the inorganic perovskite light-absorbing layer).

[0044] The preparation process of the precursor solution is as follows: CsI, PbI2 and PbBr2 are dissolved together with 3,4-thiophene dicarboxylic anhydride powder in DMSO solvent at a molar ratio of 2:1:1, and stirred at 60 °C for 2 hours to obtain a mixed precursor solution with a CsPbI2Br concentration of 1.2 M and a 3,4-thiophene dicarboxylic anhydride concentration of 2.0 mg / mL. The solution is then filtered and set aside for later use.

[0045] S4: Coat the inorganic perovskite light-absorbing layer obtained in step S3 with a hole transport layer solution to obtain the hole transport layer; specifically: spin-coat a P3HT chlorobenzene solution with a concentration of 10 mg / mL on the surface of the obtained CsPbI2Br active layer film at a spin-coating rate of 4000 rpm / min for 30 s to obtain the P3HT hole transport layer.

[0046] S5: The top electrode is obtained by vapor deposition of metal material on the hole transport layer obtained in step S4; specifically, metal Au is vapor deposited on the surface of the P3HT hole transport layer to obtain an Au top electrode with a thickness of 80 nm.

[0047] Example 2 This embodiment provides an inorganic perovskite solar cell doped with an additive containing carboxylic anhydride groups and its preparation method. The additive containing carboxylic anhydride groups in this embodiment is 2,3-pyridinedicarboxylic anhydride, and its molecular structure is as follows: Figure 2 As shown.

[0048] The preparation process of this embodiment is the same as that of Example 1, except that in step S3, the precursor solution used to prepare the inorganic perovskite light-absorbing layer is 2,3-pyridine dicarboxylic anhydride powder added to a CsPbI2Br DMSO solution, so that the concentration of 2,3-pyridine dicarboxylic anhydride in the precursor solution is 2.0 mg / mL. The remaining steps and parameters are the same as those in Example 1.

[0049] Example 3 This embodiment provides an inorganic perovskite solar cell doped with an additive containing carboxylic anhydride groups and its preparation method. The additive containing carboxylic anhydride groups in this embodiment is 2,3-pyrazine dicarboxylic anhydride, and its molecular structure is as follows: Figure 2 As shown.

[0050] The preparation process of this embodiment is the same as that of Example 1, except that in step S3, the precursor solution used to prepare the inorganic perovskite light-absorbing layer is made by adding 2,3-pyrazine dicarboxylic anhydride powder to a CsPbI2Br DMSO solution, so that the concentration of 2,3-pyrazine dicarboxylic anhydride in the precursor solution is 2.0 mg / mL. The remaining steps and parameters are the same as those in Example 1.

[0051] Comparative Example 1 This comparative example provides an undoped inorganic perovskite solar cell and its preparation method. The difference from Example 1 is that this comparative example did not undergo additive engineering treatment (i.e., no additives containing carboxylic anhydride groups were added to the precursor solution). The specific preparation process of this cell includes the following steps: S1: Clean the conductive transparent substrate and perform ultraviolet ozone treatment; the specific operation is the same as in Example 1.

[0052] S2: Coat the conductive transparent substrate after step S1 with an electron transport layer solution, and then anneal it to obtain the electron transport layer; the specific operation is the same as in Example 1.

[0053] S3: Coat the electron transport layer obtained in step S2 with an inorganic perovskite precursor solution without additives, and obtain an inorganic perovskite light-absorbing layer by gradient annealing; specifically: drop a conventional CsPbI2Br perovskite precursor solution onto the SnO2 electron transport layer, run at 1000 rpm / min for 10 s and at 2000 rpm / min for 120 s respectively to obtain a transparent perovskite wet film; then anneal the perovskite wet film at 50 ℃ for 2 min and at 160 ℃ for 10 min respectively to obtain a CsPbI2Br active layer film.

[0054] The preparation process of the conventional CsPbI2Br perovskite precursor solution is as follows: CsI, PbI2 and PbBr2 are dissolved in DMSO solvent at a molar ratio of 2:1:1, and stirred at 60 °C for 2 hours to obtain a conventional CsPbI2Br perovskite precursor solution with a concentration of 1.2 M, which is then filtered and used for later use.

[0055] S4: Coat the inorganic perovskite light-absorbing layer obtained in step S3 with a hole transport layer solution to obtain the hole transport layer; the specific operation is the same as in Example 1.

[0056] S5: The top electrode is obtained by vapor deposition of metal material on the hole transport layer obtained in step S4; the specific operation is the same as in Example 1.

[0057] The following provides performance tests for the above embodiments and comparative examples, including: Phase structure characterization of inorganic perovskite thin films: Phase analysis of the CsPbI2Br active layer films prepared in Comparative Example 1 and Examples 1-3 was performed using X-ray diffraction (XRD). The results are as follows: Figure 3 As shown in the figure. Comparative analysis shows that, compared with Comparative Example 1 without any additives, the CsPbI2Br films in Examples 1-3 exhibit significantly enhanced diffraction peak intensities, indicating that the films obtained in the examples have stronger crystallinity. This result proves that the introduction of additives containing carboxylic anhydride groups can effectively guide the ordered growth of inorganic perovskite films, thereby obtaining a more stable phase and a more orderly crystal structure.

[0058] Surface morphology characterization of inorganic perovskite thin films: The microstructure of the CsPbI2Br active layer films in Comparative Example 1 and Examples 1-3 was observed using scanning electron microscopy (SEM), and the results are as follows: Figure 4As shown in the figure, the comparison reveals that, under the regulatory effect of additives containing carboxylic anhydride groups, the crystal size of the films in Examples 1-3 is significantly increased compared to Comparative Example 1, and the number of grain boundaries is significantly reduced, resulting in a more compact overall film. This characterization result directly demonstrates the beneficial effect of additives containing carboxylic anhydride groups in regulating the crystallization kinetics of inorganic perovskites; that is, by delaying the nucleation rate, they promote sufficient crystal growth, which plays a crucial role in improving the photoelectric performance of solar cells.

[0059] Photoelectric performance testing under simulated sunlight: The inorganic perovskite solar cells prepared in Comparative Example 1, Example 1, Example 2, and Example 3 were placed in a 100 mW / cm² solar cell. 2 The test was conducted using an AM1.5G solar simulator with varying light intensity. The test environment was atmospheric, with an applied bias voltage ranging from -0.2V to 1.5V. There were 60 test points, and a stainless steel black metal sheet was used to control the incident light area to 0.1 cm². 2 Its current density-voltage (JV) test curve is as follows: Figure 5 As shown in Table 1, the specific photoelectric performance parameters are as follows.

[0060] Table 1 Performance parameters of different inorganic perovskite solar cells As shown in Table 1, compared to Comparative Example 1 without additives, the photoelectric conversion efficiency of Examples 1-3, which were doped with additives containing carboxylic anhydride groups, was increased. The improvement in open-circuit voltage (Voc) was particularly significant, with Example 1 reaching a maximum of 1.42 V. This overall performance improvement demonstrates the significant technical advantages of additives containing carboxylic anhydride groups in optimizing film quality and suppressing non-radiative recombination losses.

[0061] Photoelectric performance testing in indoor low-light environments: To meet the needs of indoor photovoltaic applications, the performance of the aforementioned devices under low-light conditions was evaluated. The test light source was LED-driven, with an illuminance of 1000 lux, and the incident light area was controlled to be 0.1 cm² using a stainless steel black metal sheet. 2 The test results are shown in Table 2.

[0062] Table 2 Indoor photoelectric performance parameters of different inorganic perovskite solar cells As shown in Table 2, compared with Comparative Example 1, the indoor photovoltaic cells doped with additives containing carboxylic anhydride groups prepared in the embodiments of the present invention also show a significant improvement in photoelectric conversion efficiency under low light conditions, with Example 1 achieving the highest efficiency of 36.22%. This indicates that the technical solution provided by the present invention is not only suitable for outdoor strong light environments, but also exhibits great application potential and commercial value in indoor light environments.

[0063] In summary, the comparative experiments of the above embodiments and comparative examples demonstrate that the present invention, by introducing carboxylic anhydride-containing additives into the inorganic perovskite precursor, can effectively regulate the crystallization kinetics of the thin film by utilizing the strong coordination between the carboxylic anhydride groups and metal ions. This induces the formation of a high-quality inorganic perovskite light-absorbing layer with large grain size, high crystallinity, and few surface defects. The characterization results and performance test data consistently show that, compared to devices without this type of molecule, the solar cells prepared according to the embodiments of the present invention achieve significant breakthroughs in open-circuit voltage and photoelectric conversion efficiency. Furthermore, they exhibit excellent performance under both strong outdoor light and weak indoor light conditions, fully demonstrating the significant enhancement effect and wide applicability of carboxylic anhydride-containing additives in improving the overall photoelectric characteristics of all-inorganic perovskite solar cells.

[0064] In the description of this invention, the references to "one embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups, characterized in that, It includes a conductive transparent substrate (1), an electron transport layer (2), an inorganic perovskite light-absorbing layer (3), a hole transport layer (4), and a top electrode (5) stacked sequentially from bottom to top; The material of the inorganic perovskite light-absorbing layer (3) includes inorganic perovskite and additives containing carboxylic anhydride groups; the additives containing carboxylic anhydride groups are one or more of 3,4-thiophene dicarboxylic anhydride, 2,3-pyridine dicarboxylic anhydride, and 2,3-pyrazine dicarboxylic anhydride.

2. The inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups according to claim 1, characterized in that, The chemical formula for the inorganic perovskite is ABX3; Where A is Cs + 、Rb + One or two of them; B is Pb 2+ Sn 2+ One or two of them; X is Cl - ,Br - I - One or more of them.

3. The inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups according to claim 2, characterized in that, The inorganic perovskite is CsPbI2Br.

4. The inorganic perovskite solar cell doped with additives containing carboxylic anhydride groups according to claim 1, characterized in that, The conductive transparent substrate (1) is one of the following: polymer substrate, indium tin oxide conductive glass, and fluorine-doped tin dioxide conductive glass; The electron transport layer (2) is made of one of the following materials: TiO2, SnO2, ZnO, Zn2SnO4, BaTiO3, SrTiO3, MgTiO3, and BaSnO3. The hole transport layer (4) is made of one of poly(3-hexylthiophene) or 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene; The material of the top electrode (5) is one of gold, silver, or conductive carbon.

5. A method for preparing an inorganic perovskite solar cell doped with an additive containing a carboxylic anhydride group as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: The conductive transparent substrate (1) is cleaned and subjected to ultraviolet ozone treatment; S2: Coat the conductive transparent substrate (1) after step S1 with an electron transport layer (2) solution and anneal it to obtain the electron transport layer (2). S3: Coat the electron transport layer (2) obtained in step S2 with an inorganic perovskite precursor solution containing carboxylic anhydride group additives, and obtain the inorganic perovskite light-absorbing layer (3) by gradient annealing. S4: Coat the inorganic perovskite light-absorbing layer (3) obtained in step S3 with a hole transport layer (4) solution to obtain the hole transport layer (4). S5: The top electrode (5) is obtained by vapor deposition of metal material on the hole transport layer (4) obtained in step S4.

6. The preparation method according to claim 5, characterized in that, In step S2, the electron transport layer (2) solution is a tin dioxide solution; The tin dioxide solution is a 2.5% solution prepared by diluting a 15% tin dioxide colloidal aqueous solution with a mixed solution of isopropanol and water.

7. The preparation method according to claim 6, characterized in that, In step S2, the coating is performed using a spin coating method, with spin coating parameters of 3000 rpm / min-4000 rpm / min for 25 s-40 s. The annealing parameters are: holding at 140 ℃-160 ℃ for 30 min-40 min.

8. The preparation method according to claim 5, characterized in that, In step S3, the preparation process of the inorganic perovskite precursor solution containing carboxylic anhydride group additives includes: dissolving lead iodide, cesium iodide, lead bromide and the carboxylic anhydride group additives in a solvent, and stirring at 60 °C to obtain a clear and transparent mixed solution. The solvent is one or both of amide solvents and sulfone solvents; The concentration of the inorganic perovskite precursor solution containing carboxylic anhydride group additives is 0.8 M-1.5 M; The concentration of the carboxylic anhydride-containing additive in the inorganic perovskite precursor solution containing the carboxylic anhydride-containing additive is 1 mg / mL to 4 mg / mL.

9. The preparation method according to claim 8, characterized in that, In step S3, the coating is performed using a spin coating method with the following parameters: running at a speed of 900 rpm / min-1100 rpm / min for 10 s-15 s, followed by running at a speed of 1900 rpm / min-2100 rpm / min for 110 s-130 s; The parameters for the gradient annealing process are as follows: first, maintain the temperature at 45 ℃-60 ℃ for 2 min-4 min, and then maintain the temperature at 150 ℃-180 ℃ for 5 min-15 min.

10. The preparation method according to claim 5, characterized in that, In step S4, the hole transport layer (4) solution is a poly-3-hexylthiophene solution, which uses chlorobenzene as a solvent and has a concentration of 8 mg / mL-15 mg / mL; the coating is performed by spin coating, and the spin coating parameters are: running at a speed of 3000 rpm / min-4000 rpm / min for 30s-40s; In step S5, the thickness of the top electrode (5) is 60 nm-80 nm.

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