A battery and a method of manufacturing the same

Abstract

In order to inhibit ion migration in a solar cell, reduce interface defects, eliminate hysteresis effect and improve long-term stability, the application provides a solar cell, which comprises a transparent conductive substrate, an electron transport layer, a composite functional interface layer, a perovskite layer, a hole transport layer and a back electrode; the composite functional interface layer comprises an inorganic oxide passivation layer arranged on one side of the electron transport layer facing the perovskite layer; the inorganic oxide passivation layer comprises a metal oxide, and the dielectric constant of the metal oxide ranges from 25 to 300 F / m.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a battery and its preparation method. Background Technology

[0002] Perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field due to their excellent photoelectric performance and low-cost potential. However, the ionic crystal properties of perovskite materials make them prone to the directional migration of mobile ions such as halide ions under operating conditions. These ions accumulate at the charge transport layer and perovskite interface, which significantly alters the interfacial band bending, thereby inducing a hysteresis effect that is direction-dependent on the current-voltage curve scan and causing performance drift problems. This severely restricts the accuracy of performance evaluation and operational reliability.

[0003] Existing technologies mostly employ organic molecules or fullerene derivatives for chemical passivation of interface defects. While these methods can improve interfacial recombination to some extent, their mechanisms are primarily limited to local bonding or filling of defect sites, making it difficult to effectively suppress long-range ion migration physically. Furthermore, the insufficient thermal stability of organic materials limits the long-term reliability of devices. In addition, some methods use inorganic barrier layers as external encapsulation layers to block water and oxygen. Located on the outermost layer of the device and not embedded in the charge transport path, these methods cannot address the hysteresis and intrinsic stability issues dominated by ion migration within the perovskite layer. In summary, existing interface modification technologies suffer from limitations such as single function, limited mechanisms of action, or improper layer placement, failing to synergistically address multiple challenges including ion migration suppression, efficient charge extraction, and interface defect passivation.

[0004] Therefore, there is an urgent need for a solar cell that can both suppress ion migration and achieve efficient charge transport, while also improving the long-term stability of the device. Summary of the Invention

[0005] The purpose of this invention is to provide a battery and its preparation method to solve the problems of ion migration suppression, efficient charge extraction and interface defect passivation that the prior art has failed to address in a synergistic manner.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] In a first aspect, the present invention provides a solar cell, the solar cell comprising a transparent conductive substrate, an electron transport layer, a composite functional interface layer, a perovskite layer, a hole transport layer, and a back electrode.

[0008] The composite functional interface layer includes an inorganic oxide passivation layer, which is disposed on the side of the electron transport layer facing the perovskite layer.

[0009] The inorganic oxide passivation layer includes a metal oxide, wherein the dielectric constant of the metal oxide is in the range of 25-300 F / m.

[0010] Optionally, the thickness of the inorganic oxide passivation layer is 3-10 nm.

[0011] Optionally, the metal oxide includes one or more of hafnium oxide, strontium titanate, zirconium oxide, titanium oxide, or doped tin dioxide.

[0012] Optionally, the doped tin dioxide includes a doping element, which includes niobium, tantalum, yttrium, lithium, magnesium, and antimony;

[0013] The molar ratio of the dopant element to tin is less than 0.1.

[0014] Optionally, the metal oxide includes titanium, and the mass content of titanium in the metal oxide is 0.5%-8%.

[0015] Optionally, the composite functional interface layer further includes a self-assembled molecular layer, which comprises an organic compound containing at least two functional groups, the functional groups being at least two of phosphonic acid, carboxyl, silyl, and amino groups.

[0016] Optionally, the organic compound includes at least one of 4-carboxyphenylphosphonic acid, 3-aminopropyltriethoxysilane, 2-aminoethylphosphonic acid, and p-aminophenylphosphonic acid.

[0017] Optionally, the perovskite layer includes a 2D perovskite layer and a 3D perovskite layer, wherein the 2D perovskite layer is disposed between the composite functional interface layer and the 3D perovskite layer.

[0018] Secondly, the present invention provides a method for preparing the above-mentioned solar cell, comprising the following steps:

[0019] An electron transport layer is prepared on a transparent conductive substrate, and the surface of the electron transport layer is pretreated with ozone.

[0020] The inorganic oxide passivation layer is deposited on the surface of the electron transport layer after ozone pretreatment using atomic layer deposition technology.

[0021] A perovskite layer is prepared on the inorganic oxide passivation layer;

[0022] A hole transport layer and a back electrode are sequentially fabricated on the perovskite light-absorbing layer.

[0023] Optionally, the ozone pretreatment method includes introducing ozone at 100℃-200℃ for 60-90 seconds, wherein the ozone concentration is >150g / Nm³. 3 .

[0024] The composite functional interface layer in the solar cell of this invention includes an inorganic oxide passivation layer composed of metal oxides with a dielectric constant between 25 and 300 F / m. These metal oxides can introduce strong dielectric polarization at the interface between the electron transport layer and the perovskite layer. The resulting reverse polarization electric field can effectively shield the built-in electric field formed by mobile ions (such as halide ions) inside the perovskite, thereby physically weakening the driving force of ion directional migration and suppressing the resulting performance hysteresis and intrinsic degradation. At the same time, the inorganic oxide passivation layer, as a dense atomic-level barrier, can physically block the penetration of ions into the charge transport layer and prevent the generation of deep-level defects by interfacial chemical reactions. The composite functional interface layer is embedded in the charge transport path, which not only solves the problem of internal ion migration that external encapsulation layers cannot handle, but also allows electrons to pass through efficiently through the tunneling effect, achieving a functional unity of ion migration suppression and efficient charge extraction, providing a structural basis for the long-term stability of the device. Detailed Implementation

[0025] To make the technical problems solved, technical solutions, and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0026] An embodiment of the present invention provides a solar cell, the solar cell comprising a transparent conductive substrate, an electron transport layer, a composite functional interface layer, a perovskite layer, a hole transport layer, and a back electrode;

[0027] The composite functional interface layer includes an inorganic oxide passivation layer, which is disposed on the side of the electron transport layer facing the perovskite layer.

[0028] The inorganic oxide passivation layer includes a metal oxide, wherein the dielectric constant of the metal oxide is in the range of 25-300 F / m.

[0029] Specifically, the dielectric constant of the metal oxide includes, but is not limited to, 25 F / m, 30 F / m, 60 F / m, 90 F / m, 120 F / m, 150 F / m, 190 F / m, 240 F / m, and 300 F / m. The composite functional interface layer in the solar cell of this invention includes an inorganic oxide passivation layer, which is composed of metal oxides with a dielectric constant between 25 and 300 F / m. These metal oxides can introduce strong dielectric polarization at the interface between the electron transport layer and the perovskite layer, and the resulting reverse polarization electric field can effectively shield mobile ions (such as halide ions) inside the perovskite. The built-in electric field formed physically weakens the driving force of ion directional migration, suppressing the resulting performance lag and intrinsic degradation. At the same time, the inorganic oxide passivation layer, as a dense atomic-level barrier, can physically block the penetration of ions into the charge transport layer, preventing the generation of deep-level defects by interfacial chemical reactions. The composite functional interface layer is embedded in the charge transport path, which not only solves the problem of internal ion migration that the external encapsulation layer cannot handle, but also ensures that electrons can pass through efficiently through the tunneling effect due to its ultra-thin characteristics. This achieves the functional unity of ion migration suppression and efficient charge extraction, providing a structural basis for the long-term stability of the device.

[0030] In some embodiments, the thickness of the inorganic oxide passivation layer is 3-10 nm.

[0031] Specifically, the thickness of the inorganic oxide passivation layer includes, but is not limited to, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, and 10nm. This thickness ensures the formation of a continuous, dense, and pinhole-free thin film, guaranteeing effective electrostatic shielding. At the same time, this ultra-thin size allows photogenerated electrons to pass through efficiently via mechanisms such as quantum tunneling, avoiding an increase in series resistance and a decrease in fill factor due to excessive layer thickness. This thickness balances electrostatic shielding effectiveness with charge transport efficiency.

[0032] In some embodiments, the metal oxide includes one or more of hafnium oxide, strontium titanate, zirconium oxide, titanium oxide, or doped tin dioxide.

[0033] Specifically, hafnium oxide has a dielectric constant of 25 F / m, and strontium titanate has a dielectric constant of 300 F / m; zirconium oxide has a dielectric constant of 25 F / m, and its physical and chemical properties are very similar to those of hafnium oxide, and it is also easy to prepare dense ultrathin films using atomic layer deposition technology; tantalum oxide has a dielectric constant of 22-26 F / m, and it has good thermal stability and dielectric properties; titanium oxide has a dielectric constant of 30-40 F / m, and it needs to be controlled by the process to maintain it in a high-resistivity state or a specific crystalline phase; the above-mentioned metal oxides generally have the characteristic of high dielectric constant, which can produce electrostatic shielding effect. Among them, doped tin dioxide maintains high dielectric properties while its conductivity can be regulated by doping, which provides a material basis for optimizing the conductivity of the interface layer and reducing charge transport loss.

[0034] In some embodiments, the doped tin dioxide includes a doping element, which includes niobium, tantalum, yttrium, lithium, magnesium, and antimony.

[0035] The molar ratio of the dopant element to tin is less than 0.1.

[0036] Specifically, the molar ratio of the dopant element to tin includes, but is not limited to, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09; to give tin dioxide strong polarization, metal elements with larger ionic radii or higher polarization can be doped into tin dioxide; niobium (Nb) doping: Nb 5+ Doping can increase the dielectric polarization of tin dioxide and improve its carrier concentration, allowing the layer structure to maintain high dielectric properties without sacrificing conductivity. Tantalum (Ta) doping: Tantalum has an extremely high intrinsic dielectric contribution; doping it into tin dioxide significantly enhances its electrostatic shielding effect on migrating ions in the perovskite layer. Yttrium (Y) doping: Yttrium doping helps stabilize the amorphous or microcrystalline structure of tin dioxide, reduces interface defects, and improves its compactness as an ion passivation layer. Doping with elements that optimize energy level matching ensures that the inorganic oxide passivation layer can both shield ions and conduct electricity through the tunneling effect. Lithium (Li) or magnesium (Mg) doping: By doping these light metals in trace amounts, the conduction band position of tin dioxide can be shifted upwards, making it closer to the conduction band bottom of the perovskite layer, thereby reducing the energy barrier at the interface and facilitating electron transport. Antimony (Sb) doping: Primarily used to significantly improve its conductivity, ensuring that electrons can be smoothly extracted even in the presence of an interface layer.

[0037] With this molar ratio of doping, an appropriate amount of shallow energy level defect states can be introduced into the tin dioxide lattice. Without compromising its high dielectric intrinsic properties, an effective electron hopping transport channel can be constructed. This allows the composite functional interface layer to take into account both the electrostatic shielding advantage brought by the high dielectric constant and the improvement of electronic conductivity, thereby synergistically reducing the tendency of ion migration and reducing the charge transport barrier.

[0038] In some embodiments, the metal oxide includes titanium, and the mass content of titanium in the metal oxide is 0.5%-8%.

[0039] Specifically, the mass content of titanium in the metal oxide includes, but is not limited to, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8%. Titanium can be doped in the form of oxides, nitrides, fluorides, or their complex salts. Titanium enters the lattice of the metal oxide in an atomically dispersed form, forming a titanium-metal composite oxide alloy phase or doped structure. While maintaining the high dielectric constant of the metal oxide to achieve electrostatic shielding, the doping of titanium introduces intermediate energy levels in the band gap that are conducive to electron transport by forming a specific band structure, thus constructing an efficient electron hopping conduction path. This physically resolves the contradiction between the insulation and charge extraction requirements of high dielectric materials, and is an important way to achieve ultrathin inorganic oxide passivation layers with both high dielectric properties and moderate conductivity. While eliminating hysteresis, the fill factor (FF) is significantly improved.

[0040] In some embodiments, the composite functional interface layer further includes a self-assembled molecular layer, which comprises an organic compound containing at least two functional groups, the functional groups being at least two of phosphonic, carboxyl, silyl, and amino groups.

[0041] Specifically, the thickness of the self-assembled molecular layer ranges from 0.5 nm to 2 nm, including but not limited to 0.5 nm, 0.8 nm, 1 nm, 1.3 nm, 1.5 nm, 1.7 nm, and 2 nm. The self-assembled molecular layer is located between the inorganic oxide passivation layer and the perovskite layer. Phosphonic acid groups and silane groups can form strong covalent bonds with the surface of the inorganic oxide passivation layer, achieving stable molecular anchoring and secondary passivation of the inorganic interface. Carboxyl groups and amino groups coordinate with lead ions in the perovskite, effectively passivating lead-related defects on the perovskite surface. The energy level alignment is finely adjusted through the formed interface dipole. This bifunctional molecular layer establishes an efficient chemical "bridge" between the inorganic oxide passivation layer and the perovskite layer, achieving atomic-level energy level alignment and grain size increase, further reducing recombination losses.

[0042] In some embodiments, the organic compound includes at least one of 4-carboxyphenylphosphonic acid, 3-aminopropyltriethoxysilane, 2-aminoethylphosphonic acid, and p-aminophenylphosphonic acid.

[0043] Specifically, the phosphonic acid group and carboxyl group at both ends of the 4-carboxyphenylphosphonic acid molecule are clearly separated in space and have strong functional orientation. This structure ensures that the molecule can bond the upper and lower layers of material simultaneously in the optimal orientation. The phosphonic acid end is firmly connected to the surface of the inorganic oxide passivation layer, and the carboxyl end interacts with the perovskite component in an oriented manner. This not only enhances the stability of the interfacial bonding, but the directional dipole moment generated can also more effectively modulate the bending of the interfacial band, optimize charge extraction, and provide uniform nucleation sites for perovskite crystallization, thus promoting the formation of a high-quality light absorption layer.

[0044] In some embodiments, the perovskite layer includes a 2D perovskite layer and a 3D perovskite layer, wherein the 2D perovskite layer is disposed between the composite functional interface layer and the 3D perovskite layer.

[0045] Specifically, the thickness of the 2D perovskite layer is 1nm~5nm, including but not limited to 1nm, 2nm, 3nm, 4nm, and 5nm; the thickness of the 3D perovskite layer is 400nm~800nm, including but not limited to 400nm, 500nm, 600nm, 700nm, and 800nm; a 2D perovskite layer is inserted between the inorganic oxide passivation layer and the 3D perovskite layer, and the 3D perovskite layer is connected to the hole transport layer, thus constructing a synergistic defense system of electrostatic shielding-energy level gradient-physical barrier. The high dielectric constant inorganic layer is responsible for providing long-range electrostatic shielding and suppressing the electric field driving force for ion migration. The 2D perovskite layer, with its hydrophobicity and large formation energy, becomes a dense chemical barrier to block ion diffusion. At the same time, its natural quantum well structure forms a gradual energy level arrangement at the interface, promoting the efficient and directional extraction of photogenerated electrons to the electrode and suppressing the backflow and recombination of holes, thereby improving stability while ensuring high conversion efficiency.

[0046] An embodiment of the present invention also provides a method for preparing the above-mentioned solar cell, comprising the following steps:

[0047] An electron transport layer is prepared on a transparent conductive substrate, and the surface of the electron transport layer is pretreated with ozone.

[0048] The inorganic oxide passivation layer is deposited on the surface of the electron transport layer after ozone pretreatment using atomic layer deposition technology.

[0049] A perovskite layer is prepared on the inorganic oxide passivation layer;

[0050] A hole transport layer and a back electrode are sequentially fabricated on the perovskite light-absorbing layer.

[0051] Specifically, depositing an inorganic oxide passivation layer on the electron transport layer using atomic layer deposition (ALD) technology is a key process for achieving an ultrathin, dense, and uniform interface structure. The inherent self-limiting surface reaction characteristics of ALD technology allow for precise control of film thickness and composition at the nanoscale, ensuring the formation of a high-quality functional layer that is free of pinholes and fully covered. This is a prerequisite for achieving effective electrostatic shielding and ion barrier.

[0052] In some embodiments, the ozone pretreatment method includes introducing ozone at 100°C-200°C for 60-90 seconds, wherein the ozone concentration is >150 g / Nm³. 3 .

[0053] Specifically, the ozone introduction temperature includes, but is not limited to, 100℃, 120℃, 150℃, 170℃, 190℃, and 200℃; the ozone introduction time includes, but is not limited to, 60 seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, 85 seconds, and 90 seconds; the strong oxidizing properties of ozone can oxidize and repair the original defects such as oxygen vacancies and low-valence metal ions on the surface of the electron transport layer in situ, significantly reducing the interface state density. This not only improves the performance of the electron transport layer itself and reduces charge recombination loss, but also provides uniform, hydroxyl-rich active nucleation sites for the subsequent deposition of a high-dielectric layer, ensuring the uniform and dense growth of the upper functional film.

[0054] The present invention will be further illustrated by the following examples.

[0055] Example 1

[0056] Example 1 illustrates the solar cell and its preparation method of the present invention, including the following steps:

[0057] 1. Cleaning of transparent conductive substrates and preparation and in-situ repair of electron transport layer (ETL):

[0058] Fluorine-doped tin oxide (FTO) conductive glass was ultrasonically cleaned sequentially in a detergent aqueous solution, deionized water, acetone, and isopropanol for 20 minutes each. After drying with nitrogen, it was treated with ultraviolet ozone (UV-Ozone) for 15 minutes. A 30 nm thick dense tin dioxide layer (electron transport layer) was then spin-coated onto the FTO. The prepared substrate was then transferred to a thermal atomic layer deposition (ALD) chamber, with the chamber temperature set at 150 °C. Before the formal ALD deposition began, a pre-ALDOxidation treatment was performed: a high concentration of ozone (O3, concentration 180 g / Nm³) was introduced. 3 (Lasts 90 seconds)

[0059] 2. Preparation of inorganic oxide passivation layer:

[0060] Atomic layer deposition of hafnium-doped titanium was performed on the electron transport layer obtained above. Precise atomic-level doping was carried out using a super-cycle mode. The ratio of Hf cycles to Ti cycles was set to 19:1 to achieve a Ti doping amount of about 5 mol%. For every 19 standard HfO2 cycles completed, one standard TiO2 cycle was inserted, and a total of about 100 cycles were performed. The deposition thickness was precisely controlled at 5 nm.

[0061] 3. Preparation of self-assembled molecular (SAM) layers:

[0062] The atomic layer deposition substrate was immersed in a 1 mmol / L solution of 4-carboxyphenylphosphonic acid (4-CPPA) in anhydrous ethanol for 10 minutes at room temperature, rinsed thoroughly with pure ethanol to remove unadsorbed molecules, and annealed at 100°C for 5 minutes.

[0063] 4. Preparation of the perovskite layer:

[0064] In a nitrogen glove box, a perovskite precursor solution was spin-coated onto the above SAM layer. The precursor formulation was: 1.5M lead iodide (PbI2) + 1.4M formamidinium iodide (FAI) + 0.1M methylammonium bromide (MABr) + 0.1M lead bromide (PbBr2) dissolved in a mixed solvent prepared by N,N-dimethylformamide (DMF):dimethyl sulfoxide (DMSO) in a 4:1 ratio. The spin-coating process was: 1000 rpm (10 s) and 4000 rpm (30 s). In the second stage (4000 rpm), 150 μL of chlorobenzene antisolvent was added dropwise with 20 seconds remaining. Annealing was performed by heating at 100°C for 60 minutes to form a black polycrystalline perovskite film.

[0065] 5. Fabrication of the hole transport layer and back electrode:

[0066] Hole transport layer (Spiro-OMeTAD): A Spiro-OMeTAD solution doped with lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and tert-butylpyridine (tBP) was spin-coated onto the above perovskite layer (4000 rpm, 30 s).

[0067] Back electrode: An 80 nm thick gold (Au) electrode is thermally evaporated and deposited on the hole transport layer under high vacuum to prepare a solar cell.

[0068] Example 2

[0069] Example 2 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those in Example 1, except that strontium titanate is used as the metal oxide.

[0070] Example 3

[0071] Example 3 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that niobium-doped tin dioxide is used as the metal oxide, and the molar ratio of niobium to tin is 0.05:0.95.

[0072] Example 4

[0073] Example 4 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those in Example 1, except that the thickness of the inorganic oxide passivation layer is 1 nm.

[0074] Example 5

[0075] Example 5 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those in Example 1, except that the thickness of the inorganic oxide passivation layer is 3 nm.

[0076] Example 6

[0077] Example 6 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those in Example 1, except that the thickness of the inorganic oxide passivation layer is 10 nm.

[0078] Example 7

[0079] Example 7 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those in Example 1, except that the thickness of the inorganic oxide passivation layer is 20 nm.

[0080] Example 8

[0081] Example 8 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that a self-assembled molecular layer is not provided.

[0082] Example 9

[0083] Example 9 is used to illustrate the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that: after the inorganic oxide passivation layer is prepared in step 2 above, 1.5 nm of phenylethylamine lead iodide (PEA2PbI4) is spin-coated as a 2D perovskite layer, and then a 3D perovskite layer is spin-coated (i.e., step 4 in Example 1). The remaining steps are the same as those of step 5.

[0084] Example 10

[0085] Example 10 illustrates the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that ozone pre-oxidation treatment is not performed in step 1.

[0086] Example 11

[0087] Example 11 is used to illustrate the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that the self-assembled molecular layer and 2D perovskite layer are not provided.

[0088] Comparative Example 1

[0089] Comparative Example 1 is used to illustrate the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that it does not contain an inorganic oxide passivation layer.

[0090] Comparative Example 2

[0091] Comparative Example 2 is used to illustrate the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that an inorganic oxide passivation layer is coated on the surface of the solar cell.

[0092] Comparative Example 3

[0093] Comparative Example 3 is used to illustrate the solar cell and its preparation method of the present invention. The preparation steps are roughly the same as those of Example 1, except that aluminum oxide (dielectric constant of 9F / m) is used instead of hafnium oxide as the metal oxide.

[0094] Performance testing

[0095] The solar cells prepared in the above embodiments and comparative examples were tested as follows:

[0096] Current density-voltage (JV) curve test procedure: A solar simulator (AM 1.5G, light intensity 100mW / cm²) was used. 2 The test was conducted using a standard silicon standard cell to calibrate the light intensity before testing. During the test, the scanning range was set to -0.1V to 1.2V, the scanning step size was 10mV, and the delay time was 100ms. Forward scanning (RS, from short circuit to open circuit) and reverse scanning (FS, from open circuit to short circuit) were performed to obtain the photoelectric conversion efficiency (PCE). The hysteresis factor HI was calculated according to the formula: HI = (PCE / (RS)) / ((RS)) / ((RS))). FS -PCE RS ) / PCE FS .

[0097] Stability Testing: Long-term operational reliability (MPPT stability) was tested under continuous illumination for 1 day (AM 1.5G), with the device biased at its maximum power point (V) using an electrochemical workstation. mppUnder voltage, the change of photocurrent density over time was continuously monitored. The ambient temperature was controlled at 25±5℃ and the relative humidity at 10%-20%. The time required for the device power output to drop to 80% of its initial value was recorded (i.e., T). 80 life).

[0098] Dark current test: Place the prepared solar cell in a glove box and cover it with aluminum foil to avoid light overnight. Perform the dark current test the next day. Do not turn on the light during the test. Set the scanning range to -1 to +1V, the scanning step size to 10mV, and the delay time to 10ms. Perform the JV test. The obtained curve is the dark current curve.

[0099] The test results of the above embodiments and comparative examples are shown in Table 1.

[0100] Table 1. Test results of solar cells in the examples and comparative examples.

[0101]

[0102] As shown in Table 1, the data of Comparative Example 1 indicates that the hysteresis factor of Comparative Example 1 is as high as 12.9% and the stability is only 68%, indicating that if an inorganic oxide passivation layer is not set, ion migration and interface recombination problems will severely restrict the device performance.

[0103] In Comparative Example 2, after placing the passivation layer on the outermost side of the battery as an encapsulation layer, its hysteresis factor (11.96%) and stability (82%) were slightly better than those of Comparative Example 1, but far inferior to those of Example 1. This indicates that interception and shielding on the ion migration path located inside the device is far more effective than external protection alone. The external encapsulation layer cannot solve the hysteresis and attenuation problems dominated by internal molecular ions.

[0104] Comparative Example 3 uses alumina, a material with a low dielectric constant, with a hysteresis factor of 10.38% and a stability of only 78.5%, proving that the dielectric constant is the key physical parameter for generating effective electrostatic shielding. Although alumina has good density and insulation properties, its dielectric constant is insufficient to form a sufficient polarization electric field to shield ions, thus failing to effectively suppress hysteresis.

[0105] Data from Example 1 shows that the solar cell of Example 1 has a maximum photoelectric conversion efficiency of 23.11% and a hysteresis factor of only 0.39%, proving that the composite functional interface layer embedded between the electron transport layer and the perovskite layer effectively suppresses ion migration through the "electrostatic shielding" effect generated by its strong dielectric polarization, thereby essentially eliminating the hysteresis phenomenon. Stability test results show that the efficiency remains at 98.5% of the initial value, and the dark current is extremely low, indicating that this dense inorganic oxide passivation layer not only provides physical barriers to prevent continuous interface degradation caused by ion penetration, but its ultra-thin characteristics also ensure efficient electron tunneling, achieving a balance between stability and efficiency. Data from Example 2 shows that using strontium titanate as a metal oxide can also suppress ion migration and improve the overall performance of the solar cell. Example 3 uses niobium-doped tin dioxide as a metal oxide, and the test results show good overall performance, proving the feasibility of using high-dielectric-constant doped tin dioxide as a passivation layer material.

[0106] The results of Examples 4-7 show that when the inorganic oxide passivation layer is too thin (1 nm), the film is discontinuous and cannot effectively shield ions, resulting in high hysteresis, poor stability, and large leakage current. When the inorganic oxide passivation layer is too thick (20 nm), although the ion shielding is extremely strong (low hysteresis), it severely hinders electron transport, resulting in a sharp drop in current density and FF, and a reverse effect on efficiency. The thickness range of the inorganic oxide passivation layer is 3-10 nm, which is a necessary condition for achieving efficient ion shielding and low-resistance electron tunneling.

[0107] Data from Example 8 shows that, compared to Example 1, the fill factor FF decreased from 81.2% to 75.5% without the SAM layer, resulting in a PCE loss of more than 2.5 percentage points. This demonstrates that the SAM layer, through its bifunctional chemical bonding, plays an irreplaceable role in optimizing interface energy level alignment, reducing contact resistance, and improving charge extraction efficiency.

[0108] Example 9 uses an inorganic oxide passivation layer + 2D perovskite layer, achieving a stability of 99.2% and a hysteresis factor of only 0.44%, demonstrating the synergistic effect of "electrostatic shielding" and "chemical / energy level barrier". The high dielectric constant inorganic oxide passivation layer is responsible for shielding electric field-driven ion migration, while the 2D perovskite layer, as a hydrophobic barrier and energy level "funnel", further blocks ion diffusion and optimizes electron extraction, thereby achieving top-level stability and voltage.

[0109] Data from Example 10 shows that the performance of ozone-free treatment (PCE 19.58%, hysteresis 1.99%, stability 85%) is significantly worse than that of Example 1, indicating that the absence of this step will result in unrepaired underlying defects, high interface state density, thereby increasing recombination, reducing Voc, and impairing long-term stability.

[0110] Data from Example 11 shows that without the self-assembled molecular layer and 2D perovskite layer, the hysteresis factor increases slightly and the stability decreases. This indicates that the self-assembled molecular layer and 2D perovskite layer can effectively avoid the problems of increased interface defects and poor energy level matching between the inorganic oxide passivation layer and the perovskite. The self-assembled molecular layer and 2D perovskite layer can improve the overall performance of solar cells.

[0111] 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 solar cell, characterized in that, The solar cell includes a transparent conductive substrate, an electron transport layer, a composite functional interface layer, a perovskite layer, a hole transport layer, and a back electrode. The composite functional interface layer includes an inorganic oxide passivation layer, which is disposed on the side of the electron transport layer facing the perovskite layer. The inorganic oxide passivation layer includes a metal oxide, wherein the dielectric constant of the metal oxide is in the range of 25-300 F / m; The thickness of the inorganic oxide passivation layer is 3-10 nm; The metal oxide includes one or more of hafnium oxide, strontium titanate, zirconium oxide, titanium oxide, or doped tin dioxide; The composite functional interface layer further includes a self-assembled molecular layer located between the inorganic oxide passivation layer and the perovskite layer. The self-assembled molecular layer includes an organic compound containing at least two functional groups, wherein the functional groups are selected from phosphonic acid, carboxyl, silyl, and amino groups.

2. The solar cell according to claim 1, characterized in that, The doped tin dioxide includes a doping element, which includes one of niobium, tantalum, yttrium, lithium, magnesium, and antimony; The molar ratio of the dopant element to tin is less than 0.

1.

3. The solar cell according to claim 1, characterized in that, The metal oxide includes titanium, and the mass content of titanium in the metal oxide is 0.5%-8%.

4. The solar cell according to claim 1, characterized in that, The organic compound includes at least one of 4-carboxyphenylphosphonic acid, 3-aminopropyltriethoxysilane, 2-aminoethylphosphonic acid, and p-aminophenylphosphonic acid.

5. The solar cell according to claim 1, characterized in that, The perovskite layer includes a 2D perovskite layer and a 3D perovskite layer, with the 2D perovskite layer disposed between the composite functional interface layer and the 3D perovskite layer.

6. The method for preparing a solar cell according to any one of claims 1-5, characterized in that, Includes the following steps: An electron transport layer is prepared on a transparent conductive substrate, and the surface of the electron transport layer is pretreated with ozone. The inorganic oxide passivation layer is deposited on the surface of the electron transport layer after ozone pretreatment using atomic layer deposition technology. A self-assembled molecular layer is prepared on the inorganic oxide passivation layer, and a perovskite layer is prepared on the self-assembled molecular layer; A hole transport layer and a back electrode are sequentially fabricated on the perovskite layer.

7. The preparation method according to claim 6, characterized in that, The ozone pretreatment method includes introducing ozone at 100℃-200℃ for 60-90 seconds, wherein the ozone concentration is >150g / Nm³. 3 .

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