Perovskite solar cell

Abstract

The invention belongs to the technical field of perovskite solar cells, and particularly relates to a perovskite solar cell. The perovskite solar cell comprises a transparent conductive substrate, and an electron transport layer, a perovskite light absorption layer, a hole transport layer and a metal electrode which are sequentially stacked on the transparent conductive substrate, and a buried interface modification layer is arranged between the electron transport layer and the perovskite light absorption layer. And the buried interface modification layer is formed by a 2-(2-oxopiperidine-4-yl) carboxylic acid derivative. Wherein the carboxyl group of the 2-(2-oxopiperidine-4-yl) carboxylic acid derivative anchors the surface of the electron transport layer to passivate oxygen vacancy defects; the amide carbonyl and uncoordinated Pb < 2 + > in the perovskite light absorption layer form a coordinate bond to inhibit non-radiative recombination; a methylene chain connecting carboxyl and a piperidone ring regulates and controls an interface dipole to optimize energy level alignment, and meanwhile, perovskite is induced to form a large-grain and low-defect thin film; the multiple defects of non-radiative recombination loss, energy level mismatch, poor crystallization and poor stability at the existing buried interface are overcome.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and specifically relates to a perovskite solar cell. Background Technology

[0002] Perovskite solar cells have attracted much attention due to their excellent photoelectric performance, low raw material costs, and simple solution processing technology. Among them, the nip-type device is a widely used typical structure. In the nip-type device structure, from bottom to top, the components are: a transparent conductive substrate, an n-type electron transport layer, an intrinsic (i-type) perovskite light-absorbing layer, a p-type hole transport layer, and a metal electrode. Tin dioxide (SnO2) is widely used as the electron transport layer in nip-type devices due to its high electron mobility, low-temperature processability, and suitable band structure. However, the buried interface between SnO2 and the perovskite light-absorbing layer has inherent defects, which severely restrict the performance of perovskite solar cells. This is mainly manifested in the high defect state density at the buried interface. Due to the large number of oxygen vacancies and uncoordinated Sn atoms on the SnO2 surface, deep-level defects are formed, becoming non-radiative recombination centers for photogenerated carriers, leading to significant losses in open-circuit voltage and fill factor. Meanwhile, the poor crystallinity of perovskite and the hydrophilicity and chemical inhomogeneity of the SnO2 surface are detrimental to the uniform spreading and ordered crystallization of the perovskite precursor, easily leading to the formation of perovskite films with small grains, numerous pinholes, and high defect density, affecting light absorption and charge transport. Furthermore, due to the energy level mismatch at the buried interface, an energy barrier exists between SnO2 and perovskite, hindering efficient electron extraction and injection. In addition, due to the poor stability of the buried interface, defects and hydrophilic groups on the SnO2 surface can induce the decomposition of perovskite materials under light and humid heat conditions, becoming channels for ion migration and accelerating device performance degradation.

[0003] To improve the performance of perovskite solar cells, existing technologies often employ single-functional small molecules for interface modification, such as compounds containing carboxyl, phosphate, or amino groups. However, these molecules struggle to simultaneously address the multiple issues mentioned above: while carboxylic acid or phosphate molecules can effectively anchor the SnO2 surface through their acidic groups, their ability to passivate perovskite defects is limited; while amide molecules rich in lone pair electrons can passivate perovskite defects, their binding force with SnO2 is weak, resulting in insufficient stability of the modified layer.

[0004] Therefore, existing technologies based on interface modification of single-function small molecules cannot effectively solve the multiple defects at the interface, such as nonradiative recombination, energy level mismatch, poor crystal quality, and weak stability, thus limiting the overall improvement in device performance. Summary of the Invention

[0005] To address the limitations of existing technologies that rely on single-functional small molecule-based interface modifications to effectively resolve multiple defects at the interface, such as nonradiative recombination, energy level mismatch, poor crystal quality, and weak stability, thereby restricting the overall performance improvement of perovskite solar cells, this invention provides a perovskite solar cell. This invention utilizes a buried interface modification layer formed from a 2-(2-oxopiridine-4-yl)carboxylic acid derivative between the electron transport layer and the perovskite light-absorbing layer. This buried interface modification layer effectively passivates surface defects in the electron transport layer, as well as defects in the perovskite bulk phase and interface, optimizes the interface energy level arrangement, and induces high-quality perovskite crystallization, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0006] This invention provides a perovskite solar cell, comprising a transparent conductive substrate and an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode sequentially stacked on the transparent conductive substrate. A buried interface modification layer is provided between the electron transport layer and the perovskite light-absorbing layer. The buried interface modification layer is formed of a 2-(2-oxopiridine-4-yl)carboxylic acid derivative, wherein the carboxyl group of the 2-(2-oxopiridine-4-yl)carboxylic acid derivative chemically bonds to the surface of the electron transport layer and binds to uncoordinated Pb in the perovskite light-absorbing layer through the amide carbonyl group on the piperidine ring. 2+ Ions form coordinate bonds; the 2-(2-oxopiridine-4-yl)carboxylic acid derivative is selected from at least one of 2-oxopiridine-4-carboxylic acid, 2,6-dioxopiridine-4-carboxylic acid and 2-(2,6-dioxopiridine-4-yl)acetic acid.

[0007] Preferably, the 2-(2-oxopiperidin-4-yl)carboxylic acid derivative is selected from at least one of the following compounds: .

[0008] Preferably, when using 2-oxopiperidin-4-carboxylic acid, the molecular formula of 2-oxopiperidin-4-carboxylic acid is C6H9NO3. This molecule has a small size, and the anchoring group is directly connected to the piperidine ring, exhibiting the strongest adsorption capacity and optimal interfacial dipole regulation capability, which is beneficial for carrier transport. When using 2,6-dioxopiperidin-4-carboxylic acid, the molecular formula of 2,6-dioxopiperidin-4-carboxylic acid is C6H7NO4. This molecule achieves a good balance between anchoring strength and passivation freedom, and has the best interfacial compatibility. When using 2-(2,6-dioxopiperidin-4-yl)acetic acid, the molecular formula of 2-(2,6-dioxopiperidin-4-yl)acetic acid is C7H9NO4. This molecule has the optimal bifunctional synergistic effect, with a balanced effect of defect passivation and crystallization regulation.

[0009] Preferably, the thickness of the buried interface modification layer is 1nm to 5nm.

[0010] Preferably, the embedded interface modification layer is prepared by the following method: A 2-(2-oxopiperidin-4-yl)carboxylic acid derivative was mixed with a solvent to obtain a mixed solution; the mixed solution was coated onto an electron transport layer and annealed to obtain a buried interface modification layer.

[0011] Preferably, the concentration of the 2-(2-oxopiperidin-4-yl)carboxylic acid derivative in the mixed solution is 0.1 mg / mL to 10 mg / mL.

[0012] Preferably, the annealing temperature is 80℃~120℃.

[0013] Preferably, when the 2-(2-oxopiridine-4-yl)carboxylic acid derivative is 2-oxopiridine-4-carboxylic acid and 2,6-dioxopiridine-4-carboxylic acid, the annealing temperature is 80°C to 100°C; when the 2-(2-oxopiridine-4-yl)carboxylic acid derivative is 2-(2,6-dioxopiridine-4-yl)acetic acid, the annealing temperature is 100°C to 120°C.

[0014] Preferably, the solvent is an alcohol solvent.

[0015] Preferably, the electron transport layer is SnO2 or TiO2, and the thickness of the electron transport layer is 30nm to 50nm.

[0016] Preferably, the perovskite light-absorbing layer has the general formula MA. 0.16 FA 0.8 Cs 0.04 Pb(I 0.85 Br 0.15 3. The thickness of the perovskite light-absorbing layer is 400nm~600nm.

[0017] Preferably, the transparent conductive substrate is a fluorine-doped tin oxide layer or an indium-doped tin oxide layer.

[0018] Compared with the prior art, the present invention has the following technical effects: 1. The perovskite solar cell of the present invention comprises a buried interface modification layer formed by a 2-(2-oxopiridine-4-yl)carboxylic acid derivative between the electron transport layer and the perovskite light absorption layer. This buried interface modification layer achieves stable anchoring and surface defect passivation by chemically bonding the terminal carboxyl groups to the surface of the electron transport layer; and by bonding the amide carbonyl groups on the piperidine ring to uncoordinated Pb in the perovskite. 2+Ions form coordination bonds to achieve Lewis base passivation of perovskite defects and suppress nonradiative recombination. Furthermore, the methylene chain connecting the carboxyl group and the piperidinone ring regulates the interfacial dipole, optimizing energy level alignment. This buried interface modification layer effectively passivates surface defects in the electron transport layer, as well as defects in the perovskite bulk phase and interface, optimizes the interfacial energy level arrangement, and induces high-quality perovskite crystallization, thereby improving the photoelectric conversion efficiency and stability of perovskite solar cells. This solves the technical problem in existing technologies where interface modification based on single-functional small molecules cannot effectively address the multiple defects at the interface, such as nonradiative recombination, energy level mismatch, poor crystal quality, and weak stability, thus limiting the overall performance improvement of perovskite solar cells.

[0019] 2. The preparation method of the buried interface modification layer of the present invention is simple, the annealing temperature is low, and it is fully compatible with the solution processing technology of mainstream nip-type perovskite solar cells, making it easy to scale up production and application. Attached Figure Description

[0020] Figure 1 This is a structural diagram of a perovskite solar cell.

[0021] Figure 2 SEM images of the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1 are shown. Among them, (a) is the SEM image of the perovskite light-absorbing layer prepared in Comparative Example 1, and (b) is the SEM image of the perovskite light-absorbing layer prepared in Example 1.

[0022] Figure 3 The JV curves are for the perovskite solar cells prepared in Examples 1 to 3 and Comparative Example 1.

[0023] Figure 4 The diagram shows the space charge confinement current of the perovskite solar cells prepared in Examples 1 to 3 and Comparative Example 1.

[0024] Figure 5 The images show the fluorescence spectra of the perovskite solar cells of Examples 1 to 3 and the FTO / SnO2 / perovskite structure in Comparative Example 1. Detailed Implementation

[0025] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0026] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0027] This invention utilizes a buried interface modification layer formed by a 2-(2-oxopiperidin-4-yl)carboxylic acid derivative between the electron transport layer and the perovskite light-absorbing layer. This buried interface modification layer achieves stable anchoring and surface defect passivation through chemical bonding between the terminal carboxyl groups and the electron transport layer surface; and through the amide carbonyl groups on the piperidine ring, it binds to uncoordinated Pb in the perovskite. 2+ Ions form coordination bonds, achieving Lewis base passivation of perovskite defects; simultaneously, the interfacial dipole is regulated by the methylene chain connecting the carboxyl group and the piperidinone ring, optimizing energy level alignment. The specific mechanism of action is as follows:

[0028] 1. Anchoring effect: chemical bonding with the electron transport layer and defect passivation.

[0029] The carboxyl groups at the molecular ends of the buried interface modification layer are the primary functional groups for achieving efficient interface modification. Their mechanism of action is mainly reflected in two aspects: First, strong chemical anchoring: the carboxyl groups in the buried interface modification layer undergo esterification with the hydroxyl groups on the surface of the SnO2 electron transport layer, forming stable covalent ester bonds. Simultaneously, the oxygen atoms in the carboxyl groups can also coordinate with uncoordinated Sn atoms on the surface of the SnO2 electron transport layer. These two strong chemical interactions ensure that the buried interface modification layer can be firmly and densely anchored to the surface of the SnO2 electron transport layer, forming a stable monolayer and preventing detachment during subsequent solution processing. Second, surface defect passivation: oxygen vacancies commonly found on the surface of the SnO2 electron transport layer are the main source of deep-level defects. The strong anchoring effect of the carboxyl groups can effectively fill these surface defect sites, significantly reducing the defect state density on the surface of the SnO2 electron transport layer, thereby suppressing the non-radiative recombination loss of photogenerated electrons during their transport to the FTO electrode.

[0030] 2. Bridging and energy level modulation: Optimizing the electronic structure of the interface.

[0031] In the buried interface modification layer, the methylene chain connecting the carboxyl group and the piperidinone ring is not only a spacer group but also plays a crucial "bridging" role. Its length has a precise regulatory effect on the physicochemical properties of the interface: On the one hand, the interface dipole and energy level alignment: The buried interface modification layer is oriented on the surface of the SnO2 electron transport layer. Its inherent molecular dipole and the redistribution of interface charge work together to introduce an interface dipole layer between the SnO2 electron transport layer and the perovskite light absorption layer. This interface dipole layer can effectively modulate the work function of the SnO2 electron transport layer surface, achieving better band alignment between its conduction band bottom and the conduction band bottom of the perovskite layer, reducing the electron extraction barrier, and improving electron extraction and transport efficiency. This is crucial for obtaining high open-circuit voltage and high fill factor. Another method is the regulation effect of carbon chain length: The carbon chain length directly affects the molecular dipole moment, packing density, and electronic coupling strength. Short-chain molecules can form denser monolayers, generating stronger dipole effects and optimizing energy level alignment; while long-chain molecules provide better insulation and physical spacing, helping to reduce charge recombination at the interface.

[0032] 3. Passivation effect: coordination with the perovskite layer and crystallization guidance.

[0033] The amide carbonyl group on the piperidine ring in the buried interface modification layer is a key functional group facing the perovskite layer, and its role is crucial: First, Lewis base passivation: the oxygen atom on the amide carbonyl group acts as a strong Lewis base, capable of reacting with uncoordinated Pb in the perovskite layer. 2+ Ions form stable Lewis acid-base adducts. This coordination effectively passivates the most significant lead-related defects at the perovskite bulk phase and interface, significantly suppressing these defects as charge recombination centers, thereby greatly reducing the non-radiative recombination probability and increasing the open-circuit voltage. Furthermore, crystallization regulation: the buried interface modification layer alters the surface energy and wettability of the SnO2 electron transport layer, providing uniform nucleation sites for the crystallization of the perovskite precursor. This induces perovskite crystals to grow along a more favorable orientation, forming high-quality polycrystalline films with larger grains, fewer grain boundaries, and higher coverage. Larger grains mean fewer grain boundary defects, while a denser film reduces leakage current paths, both contributing to improved device performance.

[0034] 4. Enhanced hydrophobic barrier and stability.

[0035] With the increase of the methylene chain length connecting the carboxyl group and the piperidinone ring in the buried interface modification layer, the hydrophobicity of the molecule is significantly enhanced. The buried interface modification layer, especially long-chain derivatives, formed between the electron transport layer and the perovskite light-absorbing layer, can act as an effective, dense, hydrophobic barrier, preventing the intrusion of water molecules from the environment. Simultaneously, this barrier can also inhibit the intrusion of I₂ in the perovskite layer. -The outward migration of plasma and the inward migration of metal ions in the SnO2 electron transport layer create a dual barrier effect. This effect fundamentally enhances the chemical stability and structural integrity of the interface, enabling perovskite solar cell devices to exhibit excellent long-term operational and environmental stability.

[0036] Example 1 A perovskite solar cell, such as Figure 1 As shown, the structure of a perovskite solar cell, from bottom to top, consists of: a fluorine-doped tin oxide (FTO) transparent conductive substrate, a tin dioxide (SnO2) electron transport layer, a buried interface modification layer, a perovskite light-absorbing layer, a phenylethyl ammonium iodide (PEAI) surface modification layer, a spiro-OMeTAD hole transport material, and a gold (Au) electrode; the specific fabrication method is as follows: S1. Synthesis of 2-oxopiperidine-4-carboxylic acid: The high-pressure hydrogenation reactor was inspected, and a pressure holding test was completed. Palladium on carbon (10%) (1.80 mmol) was added. After deoxygenation by bubbling with methanol and nitrogen for 10 min, 2-hydroxyisonicotinic acid (35.94 mmol) was dissolved in 100 mL of methanol and added to the reactor. The reactor was purged with nitrogen three times, followed by hydrogen three times. The hydrogen pressure was increased to 0.4 MPa, and the reaction was started and heated for 18 h. After the reaction was completed, the temperature was lowered, the pressure was slowly released, and the reactor was purged with nitrogen three times. The reaction solution was passed through a diatomaceous earth funnel to remove the catalyst, concentrated under reduced pressure to remove the solvent, and the crude product was slurried with diethyl ether, filtered, and vacuum dried to obtain solid 2-oxopiperidin-4-carboxylic acid, with a yield of 87%. The specific synthetic route is as follows:

[0037] .

[0038] S2. Fabrication of perovskite solar cells: The FTO transparent conductive glass was ultrasonically cleaned sequentially with deionized water, ethanol, and isopropanol for 15 minutes each, dried with nitrogen, and then treated with ultraviolet ozone for 20 minutes. A SnO2 dispersion was spin-coated onto the FTO surface (3000 rpm, 30 seconds) and annealed at 150°C for 30 minutes to form a 50 nm thick SnO2 layer, which served as the electron transport layer.

[0039] 2-O-piperidine-4-carboxylic acid was dissolved in anhydrous isopropanol to obtain a mixed solution with a concentration of 1 mg / mL; the mixed solution was spin-coated onto the surface of the electron transport layer at a speed of 3000 rpm for 30 seconds; then, it was annealed at 100 °C for 10 minutes to obtain a buried interface modification layer with a thickness of 3 nm.

[0040] 1.1 mol / L PbI₂, 0.2 mol / L MABr, 0.2 mol / L PbBr₂, 1 mol / L FAI, and 0.06 mol / L CsI were dissolved in 1250 μL of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. The solution was shaken at room temperature for 3 h to obtain a 1.5 M precursor solution. The precursor solution was spin-coated onto the surface of the buried interface modification layer. After spin-coating at 500 rpm for 5 seconds, the solution was spin-coated at 4000 rpm for 30 seconds. 200 μL of chlorobenzene was added dropwise at the 15th second of spin-coating. The solution was then annealed at 100 °C for 30 min to obtain a perovskite light-absorbing layer with a thickness of 500 nm.

[0041] Phenethyl ammonium iodide was dissolved in isopropanol to obtain a 3 mg / mL PEAI solution. The PEAI solution was spin-coated onto the surface of the perovskite light-absorbing layer at 5000 rpm for 30 seconds and then annealed at 100°C for 10 minutes to obtain the PEAI layer, which serves as the hole transport layer.

[0042] A solution of 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (spiro-OMeTAD) was spin-coated onto the surface of the hole transport layer at 4000 rpm for 30 seconds and left to stand in the dark at room temperature for 12 hours. An 80 nm Au electrode was then thermally evaporated to deposit the perovskite solar cell.

[0043] Example 2 A perovskite solar cell, the specific fabrication method of which is as follows: S1. Synthesis of 2,6-dioxopiperidine-4-carboxylic acid: The high-pressure hydrogenation reactor was inspected, and a pressure holding test was completed. Palladium on carbon (10%) (2.58 mmol) was added. After deoxygenation by bubbling methanol and nitrogen for 10 min, 2,6-dihydroxyisonicotinic acid (51.58 mmol) was dissolved in 120 mL of methanol and added to the reactor. The reactor was purged with nitrogen three times, followed by hydrogen three times. The hydrogen pressure was increased to 0.4 MPa, and the reaction was started and heated for 18 h. After the reaction was completed, the temperature was lowered, the pressure was slowly released, and the reactor was purged with nitrogen three times. The reaction solution was passed through a diatomaceous earth funnel to remove the catalyst, concentrated under reduced pressure to remove the solvent, and the crude product was separated by reverse-phase flash separation to obtain solid 2,6-dioxopiperidine-4-carboxylic acid, with a yield of 25.2%. The specific synthetic route is as follows:

[0044] .

[0045] S2. Fabrication of perovskite solar cells: The preparation method is the same as that of the perovskite solar cell in Example 1, except that 2,6-dioxopiperidine-4-carboxylic acid is used to prepare the buried interface modification layer.

[0046] 2,6-dioxopiperidine-4-carboxylic acid was dissolved in anhydrous ethanol to obtain a mixed solution with a concentration of 1.5 mg / mL; the mixed solution was spin-coated onto the surface of the electron transport layer at a speed of 3000 rpm for 30 seconds; then, it was annealed at 100 °C for 10 minutes to obtain a buried interface modification layer with a thickness of 2 nm.

[0047] Example 3 A perovskite solar cell, the specific fabrication method of which is as follows: S1. Synthesis of 2-(2,6-dioxopiperidin-4-yl)acetic acid: Palladium on carbon (10%) (1.33 mmol) was added to a glass reaction flask, and oxygen was removed by bubbling with methanol and nitrogen for 10 min. Diethyl 3-(cyanomethylene)glutarate (22.2 mmol) was dissolved in 60 ml of methanol and added to the glass reaction flask. After purging with nitrogen three times, the gas was then purged three times with a hydrogen balloon. The reaction was pressurized and heated for 36 h. After the reaction was completed, the temperature was lowered and the pressure released. The reaction solution was passed through a diatomaceous earth funnel to remove the catalyst, concentrated under reduced pressure to remove the solvent, and purified by high-vacuum distillation to obtain intermediate 1, with a yield of 53%. The specific synthetic route is as follows:

[0048] .

[0049] Intermediate 1 (1.33 mmol) was dissolved in 15 mL of glacial acetic acid, and 1 mL of concentrated sulfuric acid was added. The mixture was heated to reflux for 2 h. The temperature was then lowered to 10 °C, 5 mL of deionized water was added dropwise, and the mixture was heated to reflux for 16 h. After the reaction was complete, the reaction mixture was extracted with ethyl acetate, the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The crude product was then subjected to reverse-phase Flash separation to obtain solid 2-(2,6-dioxopiridine-4-yl)acetic acid, with a yield of 46%. The specific synthetic route is as follows:

[0050] .

[0051] S2. Fabrication of perovskite solar cells: The preparation method is the same as that of the perovskite solar cell in Example 1, except that 2-(2,6-dioxopiperidin-4-yl)acetic acid is used to prepare the buried interface modification layer.

[0052] 2-(2,6-dioxopiperidin-4-yl)acetic acid was dissolved in anhydrous ethanol to obtain a mixed solution with a concentration of 2 mg / mL; the mixed solution was spin-coated onto the surface of the electron transport layer at a speed of 3000 rpm for 30 seconds; then, it was annealed at 100 °C for 10 minutes to obtain a buried interface modification layer with a thickness of 3 nm.

[0053] Comparative Example 1 A perovskite solar cell, the specific fabrication method of which is as follows: The fabrication method is the same as that of the perovskite solar cell in Example 1, except that a buried interface modification layer is not spin-coated between the electron transport layer and the perovskite light absorption layer.

[0054] Test 1: Scanning electron microscopy (SEM) tests were performed on the perovskite light-absorbing layers prepared in Example 1 and Comparative Example 1, respectively. The results are as follows: Figure 2 As shown.

[0055] from Figure 2 SEM images revealed that the perovskite grain size increased after modification with the buried interface modification layer. This indicates that the presence of the modifying molecules altered the nucleation and growth kinetics of perovskite on the SnO2 layer. This is because the amino or carbonyl groups of the modifying molecules interact weakly with the perovskite precursor (especially PbI2) or intermediate phase, acting as a "grain growth regulator." Simultaneously, the increased perovskite grain size directly leads to a reduction in grain boundaries, which are ion migration channels and defects (such as uncoordinated Pb). 2+ The enrichment region of halogen vacancies further proves that the buried interface modification layer in Example 1 passivates interface defects.

[0056] Test 2: The performance of the perovskite solar cells prepared in Examples 1 to 3 and Comparative Example 1 was tested, and the results are shown in Table 1 and 2. Figure 3 As shown.

[0057] As shown in Table 1 and Figure 3 As shown, among the four perovskite solar cells, the perovskite solar cell of Example 2 achieved the highest open-circuit voltage (1.15V), the best fill factor (80.53%), and the highest photoelectric conversion efficiency (22.65%). This is attributed to the effective optimization of interface energy level matching by the C=O groups introduced into its molecule, thereby reducing series resistance, suppressing leakage current, and making the JV curve shape closer to the ideal rectangle. The perovskite solar cell of Example 1 exhibited the highest short-circuit current (24.50mA / cm). 2 This indicates that it has a strong carrier transport capability. The performance of the perovskite solar cell in Comparative Example 1 is relatively low.

[0058] Therefore, preparing a buried interface modification layer using 2-(2-oxopiperidin-4-yl)carboxylic acid derivatives is an effective means to improve device efficiency, especially the comprehensive effect of introducing C=O groups on a six-membered heterocycle (i.e., the buried interface modification layer in Example 2).

[0059] Table 1 Electrical performance data of perovskite solar cells Test 3: The perovskite solar cells prepared in Examples 1-3 and Comparative Example 1 were subjected to space charge confinement current testing, and the results are as follows: Figure 4 As shown.

[0060] like Figure 4 As shown, after this molecular modification, the trap filling threshold voltage (V) is... TFL The effective defect state density of the perovskite film (especially in the region near the SnO2 interface) decreased significantly. This is directly attributed to the strong coordination ability of the "amide carbonyl group" (C=O) in the molecule. The lone pair electrons of this carbonyl oxygen can effectively bind to the uncoordinated Pb in the perovskite. 2+ Defects combine to form stable coordination bonds, thereby "passivating" these deep-level traps and suppressing nonradiative recombination.

[0061] Furthermore, photoluminescence (PL) tests will be performed on the simplified FTO / SnO2 / perovskite structure in Example 1, such as... Figure 5 As shown, the strong photorecombination potential (PL) in Comparative Example 1 indicates the presence of an energy barrier or poor contact at the interface, preventing photogenerated electrons from being efficiently injected from the perovskite into SnO2. These electrons become trapped within the perovskite layer and are ultimately consumed primarily through radiative recombination (luminescence) or non-radiative recombination at defects. After modification with the buried interface modification layer, the PL in Examples 1-3 is quenched. This demonstrates that molecular modification with the buried interface modifier significantly improves the extraction and transport of photogenerated electrons from the perovskite to SnO2, kinetically quenching the radiative recombination process. This is attributed to the molecule's dual function: on one hand, the carboxyl group forms a stable chemical anchor with the SnO2 surface; on the other hand, the amide and alkyl chains tightly bind to the perovskite layer, forming a "molecular bridge" between them. This reduces the physical contact gap, optimizes the energy level arrangement, and lowers the electron injection barrier. On the other hand, the length and flexibility of the methylene chain connecting the carboxyl group and the piperidone ring affect the molecular arrangement, interfacial dipole, and initial growth of the perovskite. This helps the hydrophobic molecular part move away from the hydrophilic SnO2 and provides a more ideal growth template for the perovskite, ultimately optimizing the tightness of the interfacial contact and the electrical properties.

[0062] In summary, this invention introduces a buried interface modification layer between the electron transport layer and the perovskite light-absorbing layer. The carboxyl groups in the buried interface modification layer anchor the SnO2 electron transport layer at the lower interface, achieving defect passivation and stable bonding. Furthermore, the methylene chain connecting the carboxyl groups and the piperidinone ring acts as a bridge, its length finely controlling the interfacial dipole and energy level structure. The amide carbonyl groups on the buried interface modification layer passivate defects in the upper perovskite light-absorbing layer and guide its high-quality crystallization. Simultaneously, the hydrophobic properties of the entire molecule collectively construct a stable interfacial barrier. This integrated "anchoring-bridging-passivation" design successfully solves multiple problems at the buried interface, including recombination loss, energy level mismatch, poor crystallization, and poor stability, making it crucial for achieving high-performance, high-stability perovskite solar cells.

[0063] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0064] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If these modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A perovskite solar cell, comprising a transparent conductive substrate and an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode sequentially stacked on the transparent conductive substrate, characterized in that, A buried interface modification layer is provided between the electron transport layer and the perovskite light absorption layer. The buried interface modification layer is formed by a 2-(2-oxopiridine-4-yl)carboxylic acid derivative, wherein the carboxyl group of the 2-(2-oxopiridine-4-yl)carboxylic acid derivative is chemically bonded to the surface of the electron transport layer, and is connected to the uncoordinated Pb in the perovskite light absorption layer through the amide carbonyl group on the piperidine ring. 2+ Ions form coordination bonds; The 2-(2-oxopiridine-4-yl)carboxylic acid derivative is selected from at least one of 2-oxopiridine-4-carboxylic acid, 2,6-dioxopiridine-4-carboxylic acid, and 2-(2,6-dioxopiridine-4-yl)acetic acid.

2. The perovskite solar cell according to claim 1, characterized in that, The thickness of the buried interface modification layer is 1nm to 5nm.

3. The perovskite solar cell according to claim 1 or 2, characterized in that, The embedded interface decoration layer is prepared by the following method: The 2-(2-oxopiperidin-4-yl)carboxylic acid derivative was mixed with a solvent to obtain a mixed solution; The mixed solution was coated onto the electron transport layer and annealed to obtain the buried interface modification layer.

4. The perovskite solar cell according to claim 3, characterized in that, The concentration of the 2-(2-oxopiperidin-4-yl)carboxylic acid derivative in the mixed solution was 0.1 mg / mL to 10 mg / mL.

5. The perovskite solar cell according to claim 3, characterized in that, The annealing temperature is 80℃~120℃.

6. The perovskite solar cell according to claim 3, characterized in that, The solvent is an alcohol-based solvent.

7. The perovskite solar cell according to claim 1, characterized in that, The electron transport layer is SnO2 or TiO2; the thickness of the electron transport layer is 30nm to 50nm.

8. The perovskite solar cell according to claim 1, characterized in that, The general formula for the composition of perovskite light-absorbing layers is MA 0.16 FA 0.8 Cs 0.04 Pb(I 0.85 Br 0.15 )3; The thickness of the perovskite light-absorbing layer is 400nm~600nm.

9. The perovskite solar cell according to claim 1, characterized in that, The transparent conductive substrate is a fluorine-doped tin oxide layer or an indium-doped tin oxide layer.

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