Perovskite layers modified with additives and their preparation methods; perovskite solar cells

Abstract

This invention relates to the field of perovskite solar cell technology, specifically to a perovskite layer modified with additives, its preparation method, and a perovskite solar cell. The perovskite component is an ABX3 type organic-inorganic halide perovskite. An additive modification layer is provided at the upper or lower interface of the perovskite layer, or the additive is uniformly distributed within the perovskite layer. The additive is a DMIP derivative, wherein the DMIP derivative is a DMIP with a functional group replacing the hydrogen atom at the 5-position of the benzene ring. This functional group forms van der Waals interactions with the X-position halide ions in the perovskite precursor, the carbonyl group of the DMIP derivative forms coordination interactions with the B-position divalent metal ions in the perovskite precursor, and the methoxy group of the DMIP derivative forms hydrogen bonds with the A-position monovalent cations in the perovskite precursor. This invention solves the problems of δ-phase residue and grain inhomogeneity inherent in solvent-free methods.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, specifically to a perovskite layer modified with additives, its preparation method, and a perovskite solar cell. Background Technology

[0002] Organic-inorganic halide perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field due to their excellent properties such as tunable bandgap, high light absorption coefficient, semi-transparency, and simple fabrication process. Over the past decade, the photoelectric conversion efficiency (PCE) of perovskite solar cells has increased significantly from 3.8% to 27.3%. Among them, formamidinium lead iodide (FAPbI3) has become the preferred perovskite material for fabricating high-efficiency perovskite solar cells due to its narrow bandgap (1.48 eV) and excellent charge transport characteristics.

[0003] FAPbI3 exists in multiple crystal forms. The photoelectrically active black α phase is thermodynamically metastable at room temperature, readily forming the photoelectrically inactive yellow δ phase, the presence of which severely reduces device efficiency. The antisolvent method rapidly extracts the precursor solvent, achieving high nucleation density and uniform film preparation, but suffers from solvent residue, poor device stability, and poor reproducibility. The antisolvent-free method is simple and suitable for large-scale preparation due to the absence of an antisolvent, but suffers from slow nucleation rates and uneven crystal growth caused by the lack of instantaneous high supersaturation. It also easily generates a large number of solvated intermediates during preparation, which hinder α phase crystallization, resulting in δ phase residue and high defect density in the film. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a perovskite layer modified with additives. The perovskite component is an organic-inorganic halide perovskite with an ABX3 type structure. An additive modification layer is provided at the upper or lower interface of the perovskite layer to jointly form the perovskite layer modified with additives, or the additives are uniformly distributed in the perovskite layer to form the perovskite layer modified with additives. The additives are DMIP derivatives, with one methoxy carbonyl group (-COOCH3) on the benzene ring carbon atom as position 1, and numbered sequentially in a clockwise direction, so that the other methoxy carbonyl group is located at position 3. The DMIP derivative is a DMIP in which the hydrogen atom at position 5 of the benzene ring is replaced by a functional group. The functional group is used to form van der Waals interactions with the X-position halide ions in the perovskite precursor, the carbonyl group of the DMIP derivative is used to form coordination interactions with the B-position divalent metal ions in the perovskite precursor, and the methoxy group of the DMIP derivative is used to form hydrogen bond interactions with the A-position monovalent cations in the perovskite precursor.

[0005] Furthermore, the functional group is selected from one of -F, -Cl, -Br, -I, -OCH3, -NH2, -OH, -NO2, -CN, -SO3H, and -CF3.

[0006] Furthermore, when an additive modification layer is provided at the upper or lower interface of the perovskite layer, the thickness of the perovskite layer is 500~800nm, and the thickness of the additive modification layer is 50~150nm; when the additive is uniformly distributed in the perovskite layer to form an additive-modified perovskite layer, the thickness of the additive-modified perovskite layer is 600~900nm.

[0007] Furthermore, the perovskite component in the perovskite precursor is an organic-inorganic halide perovskite with an ABX3 type structure, wherein the A-site ion is selected from MA. + FA + Cs + and Rb + One or more of them, the B-site ion is selected from Pb 2+ and Sn 2+ One or more of them, wherein the X-site ion is selected from Cl. - ,Br - and I - One or more of them.

[0008] Furthermore, the structure in which the additive is uniformly distributed in the perovskite layer is obtained by adding 0.1~2.0 mol% of the additive to a 1.1 mol / L perovskite precursor solution to obtain a mixed solution, and then coating and annealing the mixed solution.

[0009] A method for preparing the above-mentioned perovskite layer modified with additives includes: When the upper interface of the perovskite layer is provided with an additive modification layer, an additive solution and a perovskite precursor solution are prepared. After coating the perovskite precursor solution on the electron transport layer or hole transport layer, the perovskite layer is obtained by annealing. After coating the perovskite layer with an additive solution, the additive modification layer is obtained by annealing. When the lower interface of the perovskite layer is provided with an additive modification layer, an additive solution and a perovskite precursor solution are prepared, and the additive solution is coated on the electron transport layer or hole transport layer and then annealed to obtain an additive modification layer. The perovskite precursor solution is coated on the additive modification layer and then annealed to obtain a perovskite layer. When the additive is uniformly distributed in the perovskite layer, the additive is added to the perovskite precursor solution and mixed to obtain a mixed solution. The mixed solution is then coated on the electron transport layer or hole transport layer and annealed.

[0010] Furthermore, when the lower interface of the perovskite layer is provided with an additive modification layer, the annealing temperature after coating the electron transport layer or hole transport layer with the additive solution is 100~110℃.

[0011] Furthermore, when an additive modification layer is provided on the upper interface of the perovskite layer, the annealing temperature after coating the perovskite layer with the additive solution is 70~90℃.

[0012] Furthermore, when the additive is uniformly distributed in the perovskite layer, the annealing temperature after coating the mixed solution onto the electron transport layer or hole transport layer is 100~110℃.

[0013] A perovskite solar cell with an additive-modified perovskite layer, from bottom to top, includes a conductive glass substrate, an electron transport layer, an additive-modified perovskite layer, a hole transport layer, and a top electrode, or from bottom to top, a conductive glass substrate, a hole transport layer, an additive-modified perovskite layer, an electron transport layer, and a top electrode.

[0014] The beneficial effects of this invention are as follows: 1. By ingeniously utilizing DMIP derivative additives with a C2-axis symmetric structure, a balanced interaction system with strong, medium, and weak gradient distributions was constructed through a three-tiered synergistic approach involving strong coordination of the dicarbonyl group, moderate hydrogen bonding of the dimethoxy group, and weak van der Waals interaction of the 5-position functional group. This system effectively competes for solvent coordination, completely suppresses the formation of solvation intermediates, and avoids the metal ion binding and α-phase crystallization hindrance caused by a single strong interaction, thus achieving precise control of perovskite crystallization kinetics throughout the entire process. Simultaneously, the symmetric structure of the DMIP derivative ensures uniform molecular dispersion in the system, avoiding localized concentration inhomogeneities and phase separation, making the perovskite crystallization process uniform and controllable, and solving the problems of δ-phase residue, grain inhomogeneity, and high defect density inherent in antisolvent-free methods.

[0015] 2. Through experimental testing, the highest power conversion efficiency (PCE) of the formally structured FAPbI3 perovskite solar cell reached 26.28%, which is 1.28 percentage points higher than that of the unmodified device (comparative example 1, PCE 25%). The open-circuit voltage (V0) of the device was also improved. OC =1.191V, fill factor (FF) = 85.6%, short-circuit current density (J) SC = 25.81 mA / cm 2Significant improvements were achieved, with excellent steady-state power output stability. The power conversion efficiency (PCE) of the inverted FAPbI3 perovskite solar cell reached 25.57%, an improvement of 0.98 percentage points compared to the unmodified device (Comparative Example 2, PCE 24.59%). Simultaneously, the current hysteresis effect was significantly reduced, with the efficiency difference between forward and reverse scans decreasing from 0.87 percentage points to 0.32 percentage points. Under a high-temperature nitrogen atmosphere at 85℃, the unencapsulated device had an average initial efficiency of 24.5%. After 1500 hours of aging, the efficiency of the unencapsulated device remained at 93.7% of its initial value, far exceeding the 77.8% of the unmodified device (average initial efficiency 24.4%).

[0016] 3. The gradient equilibrium regulation mechanism of this invention is independent of specific perovskite components and is applicable to all ABX3-type organic-inorganic halide perovskite systems. DMIP derivatives can effectively regulate the crystallization of different systems, addressing their inherent crystallization challenges. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the basic structure of the perovskite solar cell of the present invention.

[0018] Figure 2 This is a schematic diagram of the hierarchical structure of the perovskite layer modified with additives according to the present invention, wherein (a) is a double-layer structure modified at the upper interface, (b) is a double-layer structure modified at the bottom, and (c) is a single-layer structure modified with a mixture.

[0019] Figure 3 The images show the in-situ UV-Vis absorption spectra of the perovskite layers in Example 1 and Comparative Example 1 of this invention.

[0020] Figure 4 The images shown are top and cross-sectional views of the SEM images of the perovskite light-absorbing layers of Embodiment 1 and Comparative Example 1 of the present invention.

[0021] Figure 5 To produce perovskite solar cells by adding different amounts of DMIP-F to the perovskite photolayer (except for the amount of DMIP-F, the other steps and conditions are the same as in Example 1) according to the steps and conditions of Example 1. V OC Statistical distribution chart of PCE.

[0022] Figure 6 The graphs show the efficiency (JV) curves of perovskite solar cells in RS mode for Embodiments 1, 10, 11 and Comparative Example 1 of the present invention.

[0023] Figure 7 The graphs show the efficiency (JV) curves of perovskite solar cells in RS and FS modes of Embodiment 12 and Comparative Example 2 of the present invention.

[0024] Figure 8 The graphs show the efficiency (JV) curves of perovskite solar cells in RS and FS modes of Embodiment 1 and Comparative Example 1 of the present invention.

[0025] Figure 9 The thermal stability of Embodiment 1 and Comparative Example 1 of the present invention at 85°C is shown.

[0026] Explanation of reference numerals in the attached figures: 1-Conductive glass substrate; 2-First transport layer; 3-Perovskite layer with additive modification; 31-Additive modification layer; 32-Perovskite layer; 4-Second transport layer; 5-Top electrode Detailed Implementation

[0027] Unless otherwise specified, all raw materials used below are commercially available products, and all methods used below are conventional methods in this field.

[0028] Among existing fabrication technologies, the antisolvent method for preparing perovskite solar cells suffers from problems such as solvent residue, poor device stability and reproducibility, and difficulty in scaling up. The antisolvent-free method, due to the lack of instantaneous high supersaturation, suffers from defects such as slow nucleation rate, uneven crystal growth, and easy generation of a large number of solvation intermediates, resulting in hindered α crystallization, easy δ phase residue, high film defect density, and low device efficiency and stability. At the same time, traditional additives cannot achieve balanced molecular interactions, making it difficult to precisely control crystallization kinetics and unable to simultaneously achieve α phase nucleation and suppress the formation of inactive phases.

[0029] Specifically, this invention provides a perovskite layer modified with additives. The perovskite component is an organic-inorganic halide perovskite with an ABX3 type structure. An additive modification layer is provided at the upper or lower interface of the perovskite layer to jointly constitute the additive-modified perovskite layer, or the additive is uniformly distributed within the perovskite layer to constitute the additive-modified perovskite layer. The additive is a DMIP derivative, numbered sequentially clockwise from the carbon atom of the benzene ring containing one methoxy carbonyl group (-COOCH3) at position 1, so that the other methoxy carbonyl group is located at position 3. The DMIP derivative is a DMIP in which the hydrogen atom at position 5 of the benzene ring is replaced by a functional group. Based on this rule, the DMIP derivative is located at the carbon atom at position 5 of the benzene ring. The functional group is used to form van der Waals interactions with the X-position halide ions in the perovskite precursor, the carbonyl group of the DMIP derivative is used to form coordination interactions with the B-position divalent metal ions in the perovskite precursor, and the methoxy group of the DMIP derivative is used to form hydrogen bond interactions with the A-position monovalent cations in the perovskite precursor.

[0030] In perovskite precursors, divalent metal ions at the B site form stable solvation intermediates with solvents such as DMF / DMSO. These intermediates are difficult to decompose during annealing; for example, in the FAPbI3 perovskite system, they tend to form a useless yellow δ phase instead of the efficient black α phase.

[0031] The carbonyl group (-C=O) forms a coordination interaction with the B-site divalent metal ion in the perovskite precursor, which is sufficient to overtake the solvent, weaken or even destroy the solvation intermediate, allowing the B-site divalent metal ion to be released during annealing.

[0032] The oxygen atom of the methoxy group (-OCH3) carries a lone pair of electrons, which can form a moderate-strength hydrogen bond with the A-site monovalent cation in the perovskite precursor. The strength of this hydrogen bond is between the coordination of the dicarbonyl group and the van der Waals interaction of the 5-position functional group. This hydrogen bond competes with the solvent molecule for the hydrogen bond binding site of the A-site monovalent cation, weakening the interaction between the A-site monovalent cation and the solvent. During annealing, the A-site monovalent cation is more likely to detach from the solvent and participate in the perovskite lattice assembly. At the same time, the hydrogen bond restricts the disordered diffusion of the A-site monovalent cation and guides the A-site monovalent cation to arrange itself in an orderly manner according to the lattice orientation during annealing. The moderate-strength hydrogen bond and the strong coordination of the dicarbonyl group form a synergy, which neither interferes with the coordination competition of the dicarbonyl group for the B-site divalent metal ion, nor hinders the A-site monovalent cation due to excessive interaction.

[0033] The 5-position functional group on the benzene ring anchors some X-position halide ions at grain boundaries and surfaces, inhibiting their migration to the electron transport layer or hole transport layer, thereby reducing interfacial recombination, hysteresis, and device degradation caused by X-position halide ion migration. On the one hand, weak van der Waals interactions make the interaction between the additive and the perovskite system more uniform, avoiding strong local interactions; on the other hand, the electronic effects of substituents (such as the strong electron-withdrawing effect of X-position halide ions) can change the electron cloud density of the benzene ring, indirectly fine-tuning the coordination strength of the dicarbonyl group, so that the coordination strength between the dicarbonyl group and the B-position divalent metal ion is just in the equilibrium range where it can compete for solvent without binding the B-position divalent metal ion, thus avoiding the lock-in effect.

[0034] In summary, the carbonyl group targets and binds to the B-site divalent metal ion through strong coordination, competing for solvent coordination and inhibiting the formation and accumulation of solvation intermediates; the methoxy group stabilizes the A-site monovalent cation through moderate hydrogen bonding and guides ordered lattice assembly; and the functional group at the 5-position of the benzene ring finely adjusts the strength of the solidification interaction through weak van der Waals interactions, inhibiting ion migration and avoiding excessive interaction. These three elements synergistically solve the crystallization inhibition problem caused by solvation intermediates, while avoiding the problems of B-site divalent metal ion binding and α-phase formation inhibition caused by a single strong interaction, ultimately achieving precise control of the perovskite crystallization kinetics throughout the entire process.

[0035] DMIP has a symmetrical molecular structure and no strong dipole-dipole interactions between molecules. It does not form aggregates in the perovskite precursor solution and can be uniformly dispersed in the whole system as a single molecule. At the same time, the molecular polarity matches the corresponding solvent and perovskite precursor, and phase separation does not occur, ensuring uniform control of the entire film. This is especially important for large-area preparation, as asymmetric molecules are prone to local concentration unevenness during film formation, resulting in poor film performance consistency. The C2 axis symmetric structure of DMIP makes the interaction between the entire molecule and perovskite ions symmetrical: (1) Two symmetrical carbonyl groups form symmetrical strong coordination with the divalent metal ion at the B site. (2) Two symmetrical methoxy groups form symmetrical moderate hydrogen bonding with the monovalent cation at the A site. (3) The substituent at the 5 position on the symmetry axis forms symmetrical weak van der Waals interaction with the halide ion at the X position. This symmetrical interaction system can act uniformly in all directions of the perovskite lattice, avoiding the generation of local stress and defects, and also making the entire crystallization process more uniform and controllable.

[0036] This symmetrical interaction system can act uniformly in all directions of the perovskite lattice, avoiding the generation of local stress and defects, and making the entire crystallization process more uniform and controllable.

[0037] For modification methods, an additive modification layer can be provided at the upper or lower interface of the perovskite layer, or the additive can be uniformly distributed in the perovskite layer. The modification scheme can be flexibly selected according to the device structure, preparation process and performance requirements. While comprehensively improving the film quality and device performance, the simplicity and scalability of the anti-solvent-free process are maintained. The following is a detailed explanation: (1) The additive is uniformly distributed in the perovskite layer, also known as blending modification, which can control the bulk phase crystallization from the source. The biggest problem of the anti-solvent-free method is that there are many solvation intermediates in the bulk phase, slow α phase nucleation, δ phase residue and uneven grains. The additive is directly incorporated into the perovskite precursor, which can intervene in the entire crystallization process. The double carbonyl, double methoxy and benzene ring 5-position substituents act simultaneously to suppress solvation intermediates and guide uniform nucleation and large grain growth throughout the entire domain. (2) An additive modification layer is provided at the lower interface of the perovskite layer, also known as buried modification, which can repair the bottom interface defects between the perovskite and the transport layer. The contact area between the bottom of the perovskite layer and the electron transport layer or hole transport layer is the region with the highest defect density and the most severe carrier recombination. The buried interface modification strategy is preferentially used in formal perovskite solar cells, which can effectively solve the problems of poor interface contact between the metal oxide electron transport layer and the perovskite, poor bottom crystallization, and high defect density. The buried interface modification strategy can also be applied to inverted structure cells to further passivate the interface defects between the organic hole transport layer and the perovskite and improve the open circuit voltage of the device. (3) Additive modification layer is set on the interface of the perovskite layer, also known as upper interface modification, which can passivate the defects on the upper surface of the perovskite. There are a large number of dangling bonds, chloride residues of divalent metal ions at B sites, and surface recombination centers on the upper surface of the perovskite film, which directly reduce the open circuit voltage and fill factor. The upper interface modification is done by applying additives afterward, which does not interfere with the bulk crystallization and only specifically passivates the surface defects. Surface interface modification strategies are preferentially used in inverted perovskite solar cells, which can effectively solve the core problems of dense surface defects, severe interfacial recombination, and easy migration of iodine ions between perovskite and fullerene electron transport layers. Surface interface strategies can also be applied to conventional structure cells to help passivate residual defects on the perovskite surface, suppress the diffusion of dopants in the hole transport layer, and further improve the open-circuit voltage and long-term stability of the device.

[0038] As one specific implementation, the functional group is selected from one of -F, -Br, -I, -OCH3, -OH, -NO2, -CN, -SO3H, -CF3, -Cl, and -NH2. The structural formulas of DMIP and its derivatives are as follows: In one specific implementation, when an additive modification layer is provided at the upper or lower interface of the perovskite layer, the thickness of the perovskite layer is 500-800 nm, and the thickness of the additive modification layer is 50-150 nm. The thickness of the perovskite layer refers to the thickness of the pure perovskite layer or the thickness of the perovskite layer when the additive is uniformly distributed within it. A lower limit thickness of 500 nm for the perovskite layer ensures sufficient absorption of visible and near-infrared light. For example, the light absorption cutoff wavelength of FAPbI3 is 840 nm, and a thickness of 500 nm can absorb more than 90% of the incident photons, providing a basis for high short-circuit current density (JSC). Below 500 nm, insufficient light absorption leads to a significant decrease in JSC. Furthermore, excessively thin films are prone to pinholes and leakage current, resulting in a significant reduction in fill factor (FF). An upper limit thickness of 800 nm ensures effective extraction of photogenerated carriers before recombination while maintaining light absorption. For example, the carrier diffusion length of FAPbI3 is 1 μm, and an 800 nm thickness falls within this diffusion length range, minimizing carrier transport loss. Above 800 nm, due to the extremely slow solvent evaporation in the anti-solvent method, a large amount of solvated intermediates remain, leading to an increase in δ-phase, grain inhomogeneity, and defect density. This results in excessively long carrier transport distances, intensified bulk recombination, and increases in FF and open-circuit voltage (V). OC The performance improvement is significant. The lower limit thickness of the additive modification layer is 50 nm. During buried modification, it can completely cover the defects on the surface of the corresponding transport layer (such as oxygen vacancies and hydroxyl groups in SnO2), forming a continuous interface buffer layer and regulating the nucleation of the perovskite bottom. During upper interface modification, it can completely cover the uncoordinated B-site divalent metal ions, dangling bonds, and chloride-rich regions of B-site divalent metal ions on the perovskite surface, eliminating surface recombination centers. Below 50 nm, the modification layer is discontinuous, with a large number of exposed areas, and interface defects cannot be effectively passivated, resulting in no significant performance improvement. The upper limit thickness of the additive modification layer is 150 nm. This ensures sufficient passivation while allowing carriers to tunnel through the modification layer without forming an insulating barrier. If it exceeds 150 nm, the excessively thick modification layer will form an insulating layer, significantly increasing the series resistance, hindering carrier extraction, and causing a sharp decline in FF and JSC.

[0039] When additives are uniformly distributed within the perovskite layer to form an additive-modified perovskite layer, the thickness of the additive-modified perovskite layer is 600–900 nm. A lower limit of 600 nm ensures that DMIP derivative molecules form a continuous and uniform grain boundary passivation network throughout the perovskite layer, while providing sufficient space for the growth of large grains penetrating vertically. If the thickness is less than 600 nm, the total amount of additive molecules per unit area is insufficient to completely cover all grain boundaries and defect sites, resulting in a significant decrease in passivation effect. Furthermore, the film thickness is insufficient to support sufficient grain growth along the vertical substrate direction, making it difficult to form a large grain structure penetrating the entire film. The number of grain boundaries actually increases, exacerbating carrier recombination. Because DMIP derivatives can suppress the formation of solvation intermediates and significantly improve the crystallinity uniformity of thick films, even at a thickness of 900 nm, a dense perovskite film with a pure α phase and no δ phase residue can still be formed. Moreover, the vertical large grain structure formed by blend modification significantly extends the effective carrier diffusion length; a thickness of 900 nm is still within the effective carrier extraction range, and bulk recombination is negligible. If the thickness exceeds 900 nm, even with the modulation of DMIP derivatives, the carrier transport distance becomes too long, and bulk recombination begins to intensify significantly, leading to increased FF and V. OC A significant decrease.

[0040] As one specific implementation method, the monovalent cation at the A site is selected from MA. + FA + Cs + and Rb + One or more of the following, wherein the divalent metal ion at the B site is selected from Pb. 2+ and Sn 2+ One or more of them, wherein the halide ion at the X-position is selected from Cl. - ,Br - and I - One or more of them.

[0041] The specific structures formed include: (1) pure phase systems: FAPbI3, MAPbI3, CsPbI3, FASnI3, etc. (2) mixed cation systems: FA 0.85 MA 0.15 PbI3, Cs 0.05 FA 0.95 PbI3, etc. (3) Mixed halide ion system: FAPbI 2.8 Br 0.2 MAPbBr3, etc. (4) Lead-free / low-lead system: Sn-Pb mixed perovskite, etc.

[0042] For various perovskite systems, the addition of DMIP derivatives solves common crystallization problems, which can be explained simply as follows: For the pure FAPbI3 system, there is a problem of easy formation of a yellow δ phase and poor stability. Adding DMIP derivatives can inhibit the formation of the δ phase, promote the crystallization of the pure α phase, and improve thermal stability. For the pure MAPbI3 system, there is a problem of excessively rapid crystallization, small grains, and many defects. Adding DMIP derivatives can regulate the nucleation rate, promote the growth of large grains, and reduce bulk defects. For the pure CsPbI3 system, there is a problem of easy phase transformation at room temperature and difficulty in forming a stable black phase. Adding DMIP derivatives can lower the nucleation barrier of the black phase and stabilize the black phase at room temperature. For mixed cation systems, there is a problem of component segregation and uneven crystallization. Adding DMIP derivatives can uniformly regulate global crystallization, inhibit component segregation, and improve film uniformity. For Sn-Pb mixed perovskites, there is a problem of easy oxidation and poor crystal quality. Adding DMIP derivatives can inhibit Sn… 2+ Oxidation improves crystallization quality and enhances device efficiency. For mixed halide ion systems, there are significant differences in crystallization rates among different halides, leading to uneven composition during film formation. Adding DMIP derivatives can simultaneously regulate the crystallization kinetics of different halides, achieving synchronized nucleation and growth, resulting in a thin film with uniform composition.

[0043] In one specific implementation, the structure in which the additive is uniformly distributed in the perovskite layer is obtained by adding 0.1~2.0 mol% of the additive to a 1.1 mol / L perovskite precursor solution to obtain a mixed solution, and then coating and annealing the mixed solution.

[0044] If the additive content is below 0.1 mol%, the number of additive molecules is insufficient to cover all nucleation sites, and crystallization can only be locally regulated. Most areas will still generate δ phase and small grains according to the original path, resulting in no significant performance improvement. If the additive content is above 2.0 mol%, excessive DMIP derivative molecules will form too many coordination complexes with B-site divalent metal ions, firmly binding the B-site divalent metal ions and significantly increasing the nucleation barrier of the α phase. This leads to delayed crystallization or even failure to form the α phase. In addition, excess additive molecules will accumulate in large quantities at grain boundaries and surfaces, forming a continuous insulating layer, which greatly increases the series resistance, hinders carrier transport, and causes a sharp decrease in fill factor and short-circuit current.

[0045] On the other hand, the present invention also provides a method for preparing the above-mentioned perovskite layer modified with additives, comprising: When the upper interface of the perovskite layer is provided with an additive modification layer, an additive solution and a perovskite precursor solution are prepared. After coating the perovskite precursor solution on the electron transport layer or hole transport layer, the perovskite layer is obtained by annealing. After coating the perovskite layer with an additive solution, the additive modification layer is obtained by annealing. When the lower interface of the perovskite layer is provided with an additive modification layer, an additive solution and a perovskite precursor solution are prepared, and the additive solution is coated on the electron transport layer or hole transport layer and then annealed to obtain the additive modification layer. The perovskite precursor solution is coated on the additive modification layer and then annealed to obtain the perovskite layer. When the additive is uniformly distributed in the perovskite layer, the additive is added to the perovskite precursor solution and mixed to obtain a mixed solution. The mixed solution is then coated on the electron transport layer or hole transport layer and annealed.

[0046] In one specific implementation, the annealing temperature after coating the electron transport layer or hole transport layer with the additive solution is 100~110℃. At this temperature, the lower limit of 100℃ ensures complete removal of residual solvent from the additive solution, forming a continuous, pinhole-free, dense modified layer. If the temperature is below 100℃, the solvent will not evaporate sufficiently, resulting in a loose and porous modified layer that cannot effectively cover defects in the transport layer. Furthermore, residual solvent will evaporate during subsequent perovskite annealing, leading to bubbles and defects at the bottom. At high temperatures of 100-110℃, the solvent evaporates rapidly, and the solution concentration increases dramatically. Additive molecules accumulate on the surface of the transport layer. Due to the presence of numerous hydroxyl (-OH) and oxygen vacancies on the surface of the electron or hole transport layer, the carbonyl groups (-C=O) of the DMIP derivative preferentially form hydrogen bonds or coordination bonds with these sites, anchoring them to the surface. The anchored molecules spontaneously arrange themselves into an ordered two-dimensional structure through intermolecular van der Waals forces and π-π interactions. The C2 axisymmetric structure of the DMIP derivative ensures the uniformity of molecular arrangement, avoiding the formation of aggregates or defects. At high temperatures of 100-110℃, the chemical bonds between the additive molecules and the surface of the electron or hole transport layer are further strengthened, forming stable covalent bonds or coordination bonds, ultimately forming a continuous, dense, and pinhole-free modified layer. At this point, the additive molecules do not diffuse into the transport layer, but only form a modification layer on the surface. This modification layer exhibits good thermal and chemical stability and will not be dissolved or destroyed during subsequent perovskite coating and annealing. The DMIP modification layer acts as a pre-nucleation template, controlling crystallization from the bottom up and simultaneously passivating bottom interface defects: solvent evaporation at high temperatures, [BX6] 4- Octahedrons preferentially coordinate with the dicarbonyl groups of the bottom DMIP derivative, forming heterogeneous nucleation on the surface of the additive-modified layer. The nucleation density is uniform and controllable. The methoxy groups of the DMIP derivative form hydrogen bonds with the monovalent cations at the A sites, guiding the octahedrons to arrange themselves in an orderly manner along the direction perpendicular to the substrate, driving the grains to grow upward, and finally forming a vertical large grain structure that penetrates the film. At the same time, the DMIP derivative passivates the interface defects between the transport layer and the bottom of the perovskite in situ, inhibiting interface recombination.

[0047] In one specific implementation, the annealing temperature after coating the perovskite layer with the additive solution is 70-90°C. At this temperature, a complete α-phase perovskite crystal has been formed, and any excessively high temperature will destroy the already crystallized film structure. Temperatures exceeding 90°C will cause the α-phase perovskite portion to transform into the δ-phase, leading to the decomposition of monovalent cations at the A-sites and the generation of defects, resulting in a sharp decline in device efficiency and stability. Annealing at 70-90℃ allows the solvent to evaporate, resulting in a uniform distribution of DMIP derivative molecules on the perovskite surface, forming an ultrathin film. The DMIP derivative molecules gain sufficient kinetic energy to undergo two-dimensional diffusion on the perovskite surface, actively seeking defect sites such as uncoordinated B-site divalent metal ions and X-site halide vacancies. The carbonyl group of the DMIP derivative forms a strong coordination bond with the uncoordinated B-site divalent metal ion, the methoxy group forms a hydrogen bond with the A-site monovalent cation, and the 5-position functional group forms a van der Waals interaction with the X-site halide ion, precisely passivating defects. After the DMIP derivative molecules form stable chemical bonds with the defect sites, no further migration occurs. Because the temperature is below 95℃ (the phase transition temperature from α to δ phase), the perovskite crystal structure remains intact, without phase transition or decomposition. The pure perovskite bulk phase crystallizes autonomously. The annealing goal is to form a complete α-phase film, reserving defect targets for subsequent surface passivation. At this stage, the substrate is an electron transport layer or hole transport layer. Without pre-deposited additives, the perovskite precursor directly nucleates and grows on the surface of the electron transport layer or hole transport layer. The solvent evaporates rapidly at high temperatures. [BX6] 4- Octahedrons spontaneously assemble into α-phase perovskite nuclei, gradually growing into dense films. Annealing fully ensures the purity of the α-phase and the integrity of the crystals, but the bulk crystal quality is slightly lower than that of the blended modification system. After annealing, a large number of uncoordinated B-site divalent metal ions, dangling bonds, and grain boundary defects naturally form on the surface of the perovskite, providing precise action sites for the subsequent surface-targeted passivation of DMIP derivatives.

[0048] In one specific implementation, the annealing temperature after coating the mixed solution onto the electron transport layer or hole transport layer is 100-110°C. Controlling the lower limit temperature at 100°C provides sufficient energy to promote the decomposition of the solvation intermediate, while controlling the upper limit temperature to not exceed 110°C controls the crystallization rate, preventing excessively rapid crystallization that could lead to uneven grain growth and increased grain boundary defects. The two symmetrical carbonyl groups of DMIP competitively substitute for [BX6] through strong coordination. 4- Solvent molecules bound to the octahedral coordination units form the thermodynamically more stable [BX6・DMIP]. 4- In this ternary complex, the two methoxy groups of the DMIP derivative bind to the surrounding A-site monovalent cations via moderate hydrogen bonding, further stabilizing the complex structure and completely avoiding the large amounts of [BX6・DMIP] required in traditional antisolvent-free methods. 4-The accumulation of solvation intermediates in the ternary complex, which have high decomposition temperatures and readily induce δ-phase formation, is facilitated by the C2 axisymmetric structure of DMIP. This ensures the uniform distribution of the complex throughout the film, laying the foundation for subsequent uniform nucleation. As the solvent continues to evaporate, the supersaturation of the system gradually increases, reaching the nucleation threshold of the α-phase perovskite. [BX6・DMIP] 4- Ternary complexes require the absorption of a certain amount of energy to decompose and release [BX6]. 4- The octahedral structure significantly enhances the nucleation barrier of the α-phase, controlling the nucleation rate within the optimal range. Due to the uniform dispersion of the DMIP derivative, the nucleation barrier also maintains uniformity, ensuring synchronous and uniform nucleation across the entire substrate surface. This avoids excessive local nucleation leading to small grains or insufficient local nucleation leading to pinholes. The 5-position functional group finely adjusts the BX6·DMIP structure through weak van der Waals interactions. 4- The stability of the ternary complex ensures that the nucleation barrier is in a state of equilibrium that both inhibits δ-phase nucleation and does not hinder α-phase nucleation. After nucleation is complete, [BX6・DMIP]... 4- The ternary complex undergoes continuous and uniform decomposition. The hydrogen bonding between the methoxy group of the DMIP derivative and the monovalent cation at the A-site guides [BX6]. 4- Octahedrons are arranged in an orderly manner along the (110) crystal plane perpendicular to the substrate, promoting vertical crystal growth. Due to uniform nucleation and controllable growth rate, adjacent nuclei do not collide and merge during growth, but grow upwards on their own, eventually forming vertically penetrating large grains. The 5-position functional group inhibits the disordered diffusion of the A-position monovalent cation through van der Waals interaction with the A-position monovalent cation, avoiding defects at the grain boundaries. When the crystal growth is basically completed, a small number of DMIP derivative molecules that have not participated in complexation will migrate and accumulate to the grain boundaries and film surface under the action of capillary forces. At the grain boundaries, the carbonyl group of the DMIP derivative coordinates with the uncoordinated B-position divalent metal cation, and the methoxy group is hydrogen bonded to the A-position monovalent cation. The 5-position functional group anchors the X-position halide ion, passivates the grain boundary defects in situ, and inhibits grain boundary recombination. On the film surface, DMIP molecules form an ultrathin passivation layer, covering the surface dangling bonds and the uncoordinated B-position divalent metal cation, eliminating the surface recombination center. The temperature of 100~110℃ ensures that all residual solvents evaporate completely and does not cause thermal decomposition of A-site monovalent cations or α-phase phase transition.

[0049] The present invention will be further described in detail below through specific embodiments, wherein all raw materials and reagents used are conventional products that can be purchased on the market.

[0050] For a detailed structure of the perovskite solar cell in this invention, please refer to [link / reference]. Figure 1From bottom to top, it includes a conductive glass substrate 1, a first transport layer 2, a perovskite layer 3 modified with additives, a second transport layer 4, and a top electrode 5. For a standard cell, the first transport layer 2 is an electron transport layer, and the second transport layer 4 is a hole transport layer. For a reverse cell, the first transport layer 2 is a hole transport layer, and the second transport layer 4 is an electron transport layer.

[0051] Figure 2 The diagram shows three modification methods for the perovskite layer 3 containing additives. Figure 2 (a) shows the structure with the upper interface modified. The additive modification layer 31 is located at the upper interface of the perovskite layer 32. The additive modification layer 31 and the perovskite layer 32 together constitute the perovskite layer 3 with additive modification. Figure 2 (b) is a subsurface modified structure, where the additive modification layer 31 is located at the lower interface of the perovskite layer 32. The additive modification layer 31 and the perovskite layer 32 together constitute the perovskite layer 3 containing additive modification. Figure 2 (c) is a blended modified structure, in which the additive is uniformly distributed in the perovskite layer to obtain the perovskite layer 3 with additive modification.

[0052] The following are the preparation steps of the perovskite solar cell of the present invention, which includes a perovskite layer modified with additives, including a normal cell and a reverse cell.

[0053] I. Taking fluorinated substituted dimethyl isophthalate derivative (DMIP-F) as an example, the preparation method of the formal battery is as follows: A formal perovskite solar cell (FTO / SnO2 / DMIP-F+FAPbI3 / Spiro-OMeTAD / Au) modified with a fluorinated substituted dimethyl isophthalate derivative (DMIP-F) specifically includes the following steps: (1) Pretreatment of FTO (fluorine-doped tin oxide) conductive glass substrate: First, the FTO glass was cut into 10cm×10cm pieces using a glass cutter, and then patterned using a nanosecond laser. After etching, the individual pieces were 1.5cm×2cm in size. The cut FTO glass was then brushed with a brush containing detergent. After brushing, the FTO glass was ultrasonically cleaned four times with pure water, isopropanol, and anhydrous ethanol (two of which were ultrasonically cleaned with pure water). Each ultrasonic cleaning lasted 20 minutes and the ultrasonic frequency was 40kHz. After cleaning, the FTO glass was dried in an oven at 80~100℃ and finally stored in a clean container.

[0054] (2) Electron transport layer preparation: SnO2 electron transport layer was prepared by chemical bath deposition (CBD). The preparation process is as follows: (2.1) Preparation of SnCl2 stock solution: Take a clean flask, add 200mL of water, and pre-cool it in a refrigerator for 30min. To prevent the water from freezing, keep the water temperature at around 2℃. Add 2.5mL of 38% concentrated hydrochloric acid to the low-temperature aqueous solution and stir well. Then add 2.5g of urea, 0.548g of stannous chloride dihydrate (SnCl2・2H2O), and 50μL of mercaptoacetic acid in sequence. Continue stirring until all reagents are fully dissolved and mixed evenly. Store the prepared stock solution in a refrigerator for later use.

[0055] (2.2) Preparation of SnO2 electron transport layer: Transfer 20 mL of the above SnCl2 mother liquor to a clean glass container, add 100 mL of pure water to dilute it thoroughly to obtain the reaction solution. Place the cleaned FTO glass with the conductive side facing up in a UVO cleaner for 30 min. After treatment, immerse the FTO glass with the reverse side facing up in the diluted reaction solution, seal the container opening with plastic wrap, and place it in a 90℃ oven for constant temperature reaction for 2 h.

[0056] (2.3) After the reaction is complete, remove the container and rinse the FTO glass with pure water 3 to 5 times. Then, sonicate for 10 minutes at a frequency of 40 kHz. After sonication, rinse the back of the glass with pure water 3 to 5 times again and continue sonication for 10 minutes. After cleaning, remove the FTO glass, dry it with an air gun, and then transfer it to a 170°C hot stage for annealing for 1 hour. After it cools naturally to room temperature, you will get an FTO conductive substrate with a SnO2 layer. Seal and store it for later use.

[0057] (3) Preparation of perovskite layers modified with additives: (3.1) Preparation of perovskite precursor solution containing fluorinated dimethyl isophthalate derivative (DMIP-F): DMIP-F solid powder was taken under a nitrogen atmosphere in a glove box, weighed accurately on an electronic balance, mixed with FAPbI3 perovskite powder, and then 2-ME / CHP mixed solvent (a binary solvent system composed of 2-methoxyethanol and N-cyclohexyl-2-pyrrolidone in a specific ratio) was added. The mixture was then placed in a shaker and shaken to completely dissolve the powder, thus obtaining a mixed precursor solution. The amount of DMIP-F incorporated in the mixed precursor solution was 1 mol%, and the concentration of the perovskite precursor was 1.1 mol / L.

[0058] (3.2) Preparation of the perovskite layer modified with additives: The FTO glass substrate with SnO2 attached and the prepared mixed precursor solution were transferred together into a glove box under a nitrogen atmosphere. 60 μL of the mixed precursor solution was pipetted and uniformly drop-coated onto the surface of the prepared SnO2 electron transport layer. Then, a spin-coating process was initiated, with the spin-coating parameters set as follows: rotation speed 5000 rpm, acceleration 1500 rpm / s, and spin-coating time 30 s. After spin-coating, a uniform wet film was formed on the substrate surface. A distributed annealing process was used, first transferring the film to a 70℃ hot stage for annealing for 5 min, then transferring it to a 100℃ hot stage for annealing for 90 min. After the solvent in the system had completely evaporated, the film was removed, thus obtaining the perovskite layer modified with additives on the electron transport layer. This layer was stored in an inert environment for later use. The thickness of the perovskite layer modified with additives prepared by this process was 600 nm.

[0059] (4) Preparation of the hole transport layer: (4.1) Preparation of hole transport layer solution for Spiro-OMeTAD (abbreviation for 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, a classic organic small molecule hole transport material): Accurately weigh 520 mg of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) powder using an analytical balance, dissolve it in 1 mL of acetonitrile (ACN), shake thoroughly and filter to obtain a Li salt stock solution; separately weigh 300 mg of cobalt bis(trifluoromethanesulfonyl)imide (Co-TFSI) powder, dissolve it in 1 mL of acetonitrile (ACN), shake thoroughly and filter to obtain a Co salt stock solution. Then weigh 91.4 mg of hole transport material Spiro-OMeTAD, and add 1 mL of chlorobenzene (CBZ), 21 μL of the above Li salt solution, 11.5 μL of the above Co salt solution and 36.5 μL of 4-tert-butylpyridine (4-tBP) to it in sequence. After sealing the mixture, place it in an oscillator and oscillate continuously until all solid components are completely dissolved, ultimately obtaining a uniform and transparent Spiro-OMeTAD solution.

[0060] (4.2) The prepared Spiro-OMeTAD solution was transferred to a nitrogen glove box. 80 μL of the solution was pipetted onto the annealed perovskite film surface using a spin coater. The spin coating process was initiated with the following parameters: spin speed 4000 rpm, acceleration 2000 rpm / s, and spin coating time 25 s. The device with the prepared hole transport layer was then transferred to a dry, clean, inert atmosphere for storage. The hole transport layer thickness obtained using this method was 300 nm.

[0061] (5) Preparation of Au top electrode: The prepared device is placed on the substrate of the vacuum evaporation apparatus. Using vacuum evaporation technology, a 100nm thick Au top electrode is deposited on the surface of the hole transport layer. Thus, a complete perovskite solar cell is prepared.

[0062] II. Taking the fluorinated substituted dimethyl isophthalate derivative (DMIP-F) as an example, the preparation method of the trans battery is as follows: A trans-structured perovskite solar cell (ITO / PTAA / FAPbI3 / DMIP-F / C) containing a fluorine-substituted dimethyl isophthalate derivative (DMIP-F). 60 +BCP / Ag), specifically including the following steps: (1) Pretreatment of ITO (Indium Tin Oxide) conductive glass substrate: First, the ITO glass was cut into 2cm×2cm pieces using a glass cutter, and then patterned using a nanosecond laser. The cut ITO glass was then brushed with a brush containing detergent. After brushing, the ITO glass was ultrasonically cleaned four times sequentially with pure water, isopropanol, and anhydrous ethanol (two times with pure water). Each ultrasonic cleaning session lasted 20 minutes at a frequency of 40kHz. After cleaning, the ITO glass was dried in an oven at 80~100℃ and finally stored in a clean container.

[0063] (2) Preparation of hole transport layer: (2.1) Preparation of SAM (Self-Assembled Monolayer Forming Reagent) Solution: Accurately weigh 2.5 mg of SAM powder using a balance, dissolve it in 1 mL of isopropanol (IPA), seal the solution, and shake it in a shaker until the powder is completely dissolved. Place the pretreated ITO glass face up in a UV ozone cleaner (UVO) for 30 min.

[0064] (2.2) The treated ITO glass substrate and the prepared SAM solution were transferred together into a nitrogen glove box. 80 μL of SAM solution was pipetted onto the ITO glass surface and then spin-coated. The spin-coating parameters were set to 4000 rpm rotation speed, 2000 rpm / s acceleration, and 30 s spin-coating time. After spin-coating, the substrate was transferred to a 100℃ hot plate for annealing for 10 min, and then removed and cooled. The hole transport layer thickness obtained using this method was 5 nm.

[0065] (3) Preparation of perovskite layers modified with additives: (3.1) Preparation of perovskite precursor solution and additive solution: Accurately weigh FAPbI3 perovskite powder on a balance and add it to 2-ME / CHP mixed solvent to obtain perovskite precursor solution; accurately weigh 1 mol% DMIP-F and add it to IPA solvent, place it in a shaker and shake until completely dissolved to obtain DMIP-F solution.

[0066] (3.2) Preparation of the perovskite layer and additive-modified layer: First, the perovskite precursor solution and DMIP-F solution were simultaneously transferred into a nitrogen glove box to ensure that the operating environment met the requirements of an inert atmosphere. 60 μL of the perovskite precursor solution was precisely measured using a pipette and uniformly dripped onto the surface of the hole transport layer. A spin coating process was used, with the spin coater started and the relevant parameters set: rotation speed of 5000 rpm, acceleration of 1500 rpm / s, and spin coating duration of 30 s. After spin coating, the substrate was immediately transferred to a 100℃ hot plate for annealing, held at that temperature for 90 min, and then removed. After the substrate cooled naturally to room temperature, 70 μL of the prepared DMIP-F solution was pipetted onto the prepared perovskite layer surface. The spin coater parameters were reset to: rotation speed of 4000 rpm, acceleration of 2000 rpm / s, and spin coating duration of 25 s. After the second spin coating, the substrate was placed on a 100°C hot plate for annealing for 5 minutes. After annealing, it was removed and a perovskite layer with additive modification was finally obtained, in which the thickness of the perovskite layer was 600 nm and the thickness of the additive modification layer was 60 nm.

[0067] (4) Fabrication of electron transport layer and Ag top electrode: The prepared device was transferred to the substrate of a vacuum evaporation apparatus, and the evaporation operation was performed in sequence under vacuum: first, C was evaporated. 60 The first thin film, with a thickness controlled at 30 nm, was deposited at a rate of 0.1 Å / s. Subsequently, a BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) thin film, with a thickness of 7 nm, was deposited at the same rate of 0.1 Å / s to obtain the electron transport layer. Finally, an Ag top electrode, with a thickness of 100 nm, was deposited at a rate adjusted to 0.2 Å / s to obtain the Ag top electrode. After all the deposition steps were completed, the fabrication of the entire device was finished, resulting in a structurally complete inverted perovskite solar cell.

[0068] According to the preparation method of the formal battery described above, Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 were prepared with 5 functional groups: -F, -Br, -I, -OCH3, -OH, -NO2, -CN, -SO3H, -CF3, -Cl, and -NH2, respectively. Comparative Example 1 was also prepared, which was identical to the preparation method of the formal battery except that no DMIP derivative additive was added. The JV test results of Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, and Comparative Example 1 are shown in Table 1. Perovskite exhibits ion migration and interfacial polarization, resulting in different JV curves and efficiencies measured by forward and reverse scans. RS refers to the reverse scan, where the voltage scans from the short-circuit voltage (0V) to the open-circuit voltage (Voc), while FS refers to the forward scan, where the voltage scans from the open-circuit voltage (Voc) to the short-circuit voltage (0V).

[0069] Table 1 shows the JV test results for Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and Comparative Example 1. According to the above-described method for preparing a trans-cell, Example 12 was prepared with the 5-position functional group being -F. Comparative Example 2 was also prepared, which was identical to the above-described method for preparing a trans-cell except that no DMIP derivative additive was added. The JV test results of Example 12 and Comparative Example 2 are shown in Table 2.

[0070] Table 2 shows the JV test results for Example 12 and Comparative Example 2. Figure 3 The in-situ UV-Vis absorption spectra of the perovskite layers in Example 1 and Comparative Example 1 of this invention are used to monitor the crystallization process during annealing. The control sample showed a significant absorption jump after annealing for 10 s, followed by a slow increase and stabilization after 60 s, indicating a transition from the solvated mesophase to the α-phase. In contrast, Example 1 showed a more stable absorption evolution and gradually stabilized after 60 s.

[0071] Figure 4These are top and cross-sectional views of SEM images of the perovskite layers of Example 1 and Comparative Example 1 of the present invention. In the top view, it can be observed that the perovskite layer of Comparative Example 1 contains a large number of residual white PbI2 particles, which are small and dispersed in size, and contain many impurities and defects. The perovskite layer of Example 1 is smoother and flatter, with almost no white PbI2 particles, and the grains are large and uniformly distributed in size, resulting in a denser film. In the cross-sectional view, the perovskite layer of Comparative Example 1 has many voids (circled in red and indicated by red arrows), indicating that the perovskite layer is not in complete contact with the upper and lower interfaces, and residual white PbI2 particles can still be observed at the interfaces. In contrast, the perovskite film of Example 1 is composed of more orderly vertically arranged large grains, resulting in a denser and more complete film.

[0072] Figure 5 To produce perovskite solar cells by adding different amounts of DMIP-F to the perovskite photolayer (except for the amount of DMIP-F, the other steps and conditions are the same as in Example 1) according to the steps and conditions of Example 1. V OC Statistical distribution of PCE. The optimal content is 0.2 mol%, at which point... V OC The fact that PCE reached its highest distribution value suggests that to achieve the expected performance, it is necessary to explore different concentrations of additives, and the content of additives should be adjusted accordingly based on different perovskite components and different solvents.

[0073] Figure 6 The table shows the efficiency curves of perovskite solar cells in RS mode for Examples 1, 10, 11 and Comparative Example 1 of the present invention. Combined with Table 1, it is found that the perovskite solar cell modified with DMIP-F has the best efficiency curve, which suggests that adding different DMIP derivative additives has different effects on the cell efficiency.

[0074] Figure 7 The table shows the efficiency curves of perovskite solar cells in RS and FS modes for Embodiment 12 and Comparative Example 2 of the present invention. Referring to Table 2, in RS mode, for Embodiment 12... V OC The open-circuit voltage is 1.190V. J SC The short-circuit current density is 25.68 mA·cm. -2 The fill factor (FF) is 0.837, which is a significant improvement compared to Comparative Example 2. The power conversion efficiency (PCE) is increased to 25.57%. Therefore, the inverted FAPbI3 perovskite solar cell modified with DMIP-F has better photoelectric performance.

[0075] Figure 8The table shows the efficiency curves of perovskite solar cells in RS and FS modes for Embodiment 1 and Comparative Example 1 of the present invention. Referring to Table 1, in RS mode, for Embodiment 1... V OC The open-circuit voltage is 1.191V. J SC The short-circuit current density is 25.81 mA·cm. -2 With a fill factor of 0.856 and a PCE (photovoltaic power conversion efficiency) of 26.28%, it can be seen that the FAPbI3 perovskite solar cell containing DMIP-F has better photoelectric performance.

[0076] Figure 9 The thermal stability of Example 1 and Comparative Example 1 at 85°C was measured. The PCE change of the unpackaged device was measured under a nitrogen atmosphere at 85°C. The device in Example 1 had an initial efficiency of 24.5% and maintained 22.95% (93.7% of the initial value) after 1500 h, while the efficiency of Comparative Example 1 decreased from 24.4% to 19.1% (77.8% of the initial value).

[0077] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A perovskite layer modified with additives, characterized in that, Its perovskite composition is an organic-inorganic halide perovskite with an ABX3 type structure. An additive modification layer is provided at the upper or lower interface of the perovskite layer to jointly form an additive-modified perovskite layer, or the additive is uniformly distributed in the perovskite layer to form an additive-modified perovskite layer. The additive is a DMIP derivative, with one of the carbon atoms on the benzene ring containing the methoxy carbonyl group as position 1, and numbered sequentially in a clockwise direction, so that the other methoxy carbonyl group is located at position 3. The DMIP derivative is a DMIP with the hydrogen atom at position 5 of the benzene ring replaced by a functional group. The functional group is used to form van der Waals interactions with the X-position halide ions in the perovskite precursor, the carbonyl group of the DMIP derivative is used to form coordination interactions with the B-position divalent metal ions in the perovskite precursor, and the methoxy group of the DMIP derivative is used to form hydrogen bond interactions with the A-position monovalent cations in the perovskite precursor.

2. The perovskite layer modified with additives according to claim 1, characterized in that, The functional group is selected from one of -F, -Br, -I, -OCH3, -OH, -NO2, -CN, -SO3H, -CF3, -Cl, and -NH2.

3. The perovskite layer modified with additives according to claim 1, characterized in that, When an additive modification layer is provided at the upper or lower interface of the perovskite layer, the thickness of the perovskite layer is 500~800nm ​​and the thickness of the additive modification layer is 50~150nm; when the additive is uniformly distributed in the perovskite layer to form an additive-modified perovskite layer, the thickness of the additive-modified perovskite layer is 600~900nm.

4. The perovskite layer modified with additives according to claim 1, characterized in that, The perovskite component in the perovskite precursor is an organic-inorganic halide perovskite with an ABX3 type structure, wherein the A-site ion is selected from MA. + FA + Cs + and Rb + One or more of them, the B-site ion is selected from Pb 2+ and Sn 2+ One or more of them, wherein the X-site ion is selected from Cl. - ,Br - and I - One or more of them.

5. The perovskite layer modified with additives according to claim 1, characterized in that, The structure in which the additive is uniformly distributed in the perovskite layer is obtained by adding 0.1~2.0 mol% of the additive to a 1.1 mol / L perovskite precursor solution to obtain a mixed solution, and then coating and annealing the mixed solution.

6. A method for preparing a perovskite layer modified with additives according to any one of claims 1 to 5, characterized in that, include: When the upper interface of the perovskite layer is provided with an additive modification layer, an additive solution and a perovskite precursor solution are prepared. After coating the perovskite precursor solution on the electron transport layer or hole transport layer, the perovskite layer is obtained by annealing. After coating the perovskite layer with an additive solution, the additive modification layer is obtained by annealing. When the lower interface of the perovskite layer is provided with an additive modification layer, an additive solution and a perovskite precursor solution are prepared, and the additive solution is coated on the electron transport layer or hole transport layer and then annealed to obtain an additive modification layer. The perovskite precursor solution is coated on the additive modification layer and then annealed to obtain a perovskite layer. When the additive is uniformly distributed in the perovskite layer, the additive is added to the perovskite precursor solution and mixed to obtain a mixed solution. The mixed solution is then coated on the electron transport layer or hole transport layer and annealed.

7. The method for preparing the perovskite layer modified with additives according to claim 6, characterized in that, When the lower interface of the perovskite layer is provided with an additive modification layer, the annealing temperature after coating the electron transport layer or hole transport layer with the additive solution is 100~110℃.

8. The method for preparing the perovskite layer modified with additives according to claim 6, characterized in that, When the upper interface of the perovskite layer is provided with an additive modification layer, the annealing temperature after coating the perovskite layer with the additive solution is 70~90℃.

9. The method for preparing a perovskite layer modified with additives according to claim 6, characterized in that, When the additive is uniformly distributed in the perovskite layer, the annealing temperature after coating the mixed solution onto the electron transport layer or hole transport layer is 100~110℃.

10. A perovskite solar cell containing an additive-modified perovskite layer according to any one of claims 1 to 5, characterized in that, The structure, from bottom to top, includes a conductive glass substrate, an electron transport layer, a perovskite layer modified with additives, a hole transport layer, and a top electrode; or the structure, from bottom to top, includes a conductive glass substrate, a hole transport layer, a perovskite layer modified with additives, an electron transport layer, and a top electrode.

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