Bimolecular synergistic interface modified perovskite solar cell and preparation method thereof

Abstract

The invention relates to the technical field of perovskite solar cells, and particularly provides a bimolecular synergistic interface modified perovskite solar cell and a preparation method thereof. The perovskite solar cell comprises a substrate, a first hole transport layer, a second hole transport layer, a perovskite light absorption layer, an electron transport layer, a hole barrier layer and an electrode which are stacked in sequence, a bimolecular modification layer composed of first organic molecules and second organic molecules is arranged between the perovskite light absorption layer and the electron transport layer. Before the electron transport layer is prepared, a first organic molecule solution and a second organic molecule solution are mixed and then applied to the surface of the perovskite light absorption layer, and annealing is carried out to form the bimolecular modification layer. According to the perovskite solar cell, a synergistic regulation effect is formed at the interface through the bimolecular modification layer, the non-radiative recombination loss can be inhibited, the defect state density can be reduced, the energy level arrangement can be optimized, and the carrier extraction can be promoted, so that the photoelectric conversion efficiency and the operation stability of the perovskite solar cell can be improved.

Description

Technical Field

[0001] This application relates to the field of perovskite solar cell technology, and more specifically, to a bimolecular synergistic interface modified perovskite solar cell and its preparation method. Background Technology

[0002] Perovskite solar cells are considered a promising new photovoltaic technology due to their high light absorption coefficient, long carrier diffusion length, and ability to be fabricated using low-temperature solution methods. In recent years, the certified efficiency of single-junction perovskite solar cells has increased to approximately 27%, approaching their theoretical limit of 33.4%. Among various perovskite systems, wide-bandgap perovskite solar cells have attracted considerable attention due to their application potential in high-voltage output and as top cells in tandem devices; their interface quality has a significant impact on the photoelectric performance of the device.

[0003] However, in wide-bandgap perovskite solar cells, the interface between the perovskite light-absorbing layer and the electron transport layer typically contains numerous defects. These defects can trigger severe nonradiative recombination, leading to open-circuit voltage loss and interface energy level mismatch, thereby reducing charge extraction and transport efficiency. Furthermore, the chemical instability at the interface accelerates the degradation of the perovskite material, severely impacting the long-term operational stability of the device. To improve interface properties, existing technologies have proposed strategies such as two-dimensional perovskite passivation, the introduction of organic ammonium salt passivators, metal oxide interface layers, or the construction of heterojunction structures. Although these methods improve defect density or energy level arrangement to some extent, most schemes rely on a single type of interface modifier, making it difficult to simultaneously achieve defect suppression and interface energy level modulation. This results in significant interface losses and limited improvements in device performance.

[0004] Therefore, there is an urgent need for an interface modulation technology that can simultaneously improve the state of interface defects and optimize the energy level arrangement of the interface, so as to further improve the performance and stability of perovskite solar cells. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing a perovskite solar cell with bimolecular synergistic interface modification and its preparation method, thereby solving the problem that interface defects and energy level mismatch are difficult to improve simultaneously in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This application provides a bimolecular synergistic interface modified perovskite solar cell, comprising a substrate, a first hole transport layer, a second hole transport layer, a perovskite light absorption layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially. A bimolecular modification layer composed of a first organic molecule and a second organic molecule is disposed between the perovskite light absorption layer and the electron transport layer.

[0007] This application constructs a bimolecular modification layer between the perovskite light-absorbing layer and the electron transport layer, formed by a first organic molecule and a second organic molecule, to achieve synergistic regulation of the interfacial charge environment and the state of interfacial defects. The first organic molecule modulates the local potential of the interfacial region through its charge distribution characteristics, making the interfacial charge environment more stable and facilitating electron transport at the interface. The second organic molecule can interact with uncoordinated ions or defect sites at the interface, thereby reducing surface inhomogeneity caused by interfacial defects and improving the interfacial state. The two types of molecules work synergistically in the same interfacial layer. The interfacial potential regulation caused by the first organic molecule is conducive to the interfacial distribution and defect binding of the second organic molecule, while the interfacial stabilization effect of the second organic molecule can enhance the interfacial retention ability of the first organic molecule. Through the above positive feedback synergistic process, the bimolecular modification layer can jointly influence the charge distribution and energy level transition characteristics of the interfacial region, achieving a more ideal interfacial regulation effect.

[0008] Furthermore, the first organic molecule and the second organic molecule are mixed and distributed within the thickness range of the bimolecular modification layer. This mixed distribution allows both types of molecules to participate simultaneously in interfacial processes such as coordination, orientation, or dipole formation, avoiding discontinuous interfacial interactions caused by localized uneven composition within the bimolecular modification layer.

[0009] Furthermore, the first organic molecule has a polar group that regulates the interfacial charge environment, and the second organic molecule has a functional group that binds to interfacial defect sites.

[0010] Furthermore, the first organic molecule is 1,3-propanediamine hydroiodate, and the second organic molecule is 3,4,5-trifluoroaniline hydrobromide. 1,3-propanediamine hydroiodate possesses the ability to modulate the local interfacial potential and improve the interfacial charge environment; 3,4,5-trifluoroaniline hydrobromide can interact with defect-related sites on the interface, making the interface more stable. By employing these two molecules, the bimolecular modified layer simultaneously possesses the molecular properties required for interfacial charge regulation and interface stabilization.

[0011] This application also proposes a method for preparing a bimolecular synergistic interface modified perovskite solar cell. The method includes sequentially preparing a first hole transport layer, a second hole transport layer, a perovskite light absorption layer, an electron transport layer, a hole blocking layer, and an electrode on a substrate. Before preparing the electron transport layer, a first organic molecule solution and a second organic molecule solution are mixed and applied to the surface of the perovskite light absorption layer, and then annealed to form a bimolecular modification layer.

[0012] The preparation method of this application involves applying two types of organic molecules in the form of a mixed solution to the surface of a perovskite light-absorbing layer, so that the two types of molecules simultaneously participate in interfacial processes such as adsorption, coordination or orientation during the interface formation process; after annealing, the molecules rearrange in the interfacial region and form a stable bimolecular modification layer, so that the interface exhibits the joint interfacial interaction of the two types of molecules.

[0013] Furthermore, the mass ratio of the first organic molecule solution to the second organic molecule solution is 1:1 to 3:1. This ratio can establish a suitable ratio for the co-deposition of the two types of molecules in the mixed solution, allowing both types of molecules to participate in the deposition process during the interface formation stage.

[0014] Furthermore, the mixed solution is applied by spin coating at a speed of 4000-6000 rpm for 20-40 seconds. Spin coating allows for the formation of a thin solution layer of controllable thickness on the surface of the perovskite light-absorbing layer through centrifugal force.

[0015] Furthermore, the annealing temperature is 80-120℃, and the annealing time is 3-10 min. Under these annealing conditions, the solvent in the mixed solution can evaporate more fully, while the adsorption and arrangement of the two types of molecules in the interfacial region gradually stabilizes.

[0016] Furthermore, the solvent for both the first and second organic molecular solutions is isopropanol. Isopropanol facilitates the mixing and dispersion of the two types of molecules in the same solvent system, which improves the stability of the subsequent application process.

[0017] Furthermore, the solvent also contains DMF. The addition of DMF can regulate the evaporation rate and wettability of the mixed solution, giving it more suitable spreading behavior when coated onto the surface of the perovskite light-absorbing layer.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This application constructs a bimolecular modification layer formed by a first organic molecule and a second organic molecule between the perovskite light-absorbing layer and the electron transport layer. This allows the interface layer to simultaneously contain molecules that can interact with interface defect sites and molecules that can modulate the interface energy level environment. The two types of molecules have a synergistic effect in the same interface layer, which helps to suppress nonradiative recombination loss at the interface, improve carrier extraction efficiency, and promote the improvement of device open-circuit voltage and operational stability. Compared with a single modifier, the bimolecular structure of this application can provide a more comprehensive interface modulation capability, thereby overcoming the problem that it is difficult to improve interface defects and energy level mismatch at the same time.

[0019] (2) In the preparation process, this application adopts a mixed application method, so that the two types of organic molecules contact the surface of the perovskite light absorption layer in the form of a common solution, thereby enabling the bimolecular modified layer to have a more stable one-time film formation process during the deposition stage, preventing water and oxygen from invading the perovskite light absorption layer; and this application method is compatible with the existing solution method preparation process, without changing the device structure or process route, and is applicable to a variety of perovskite solar cell systems, with good process adaptability. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of a bimolecular synergistic interface modified perovskite solar cell provided by the present invention; Figure 2 A flowchart illustrating a method for preparing a bimolecular synergistic interface-modified perovskite solar cell provided by the present invention; Figure 3 This is a comparison of the JV curves of the perovskite solar cells prepared in the experimental group and the control group in Example 2 of the present invention. Figure 4 This is a comparison of the incident quantum efficiency (EQE) spectra of the perovskite solar cells prepared in the experimental group and the control group in Example 2 of the present invention.

[0021] Icons: 1-Substrate; 2-First hole transport layer; 3-Second hole transport layer; 4-Perovskite light absorption layer; 5-Biomer modification layer; 6-Electron transport layer; 7-Hole blocking layer; 8-Electrode. Detailed Implementation

[0022] To make the implementation process of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings.

[0023] Example 1: This invention provides a perovskite solar cell with bimolecular synergistic interface modification, such as... Figure 1 As shown, the structure includes a substrate 1, a first hole transport layer 2, a second hole transport layer 3, a perovskite light absorption layer 4, an electron transport layer 6, a hole blocking layer 7, and an electrode 8, which are stacked in sequence. A bimolecular modification layer 5 composed of a first organic molecule and a second organic molecule is disposed between the perovskite light absorption layer 4 and the electron transport layer 6.

[0024] The substrate 1 is a transparent conductive glass, such as FTO or ITO, with a thickness of 0.6-2 mm, a sheet resistance of approximately 10 Ω / sq, and dimensions of 2 cm × 2 cm. This substrate 1 also serves as the front electrode, supporting the upper functional layer and collecting and transporting photogenerated carriers. The first hole transport layer 2 is disposed on the substrate 1 and is made of NiO. xThe first hole transport layer 4 exhibits high hole selectivity, collecting holes transported from the perovskite light-absorbing layer 4 while improving the wettability of the overlying solution and promoting the uniform spreading of the perovskite precursor solution. The second hole transport layer 3, disposed above the first hole transport layer 2, is a self-assembled monolayer (SAM), preferably 4PADCB, 2PACz, or Me-4PACz. It possesses a dense and highly oriented molecular structure, thus forming excellent interfacial contact and enhancing hole extraction. 4PADCB is preferably used for the second hole transport layer 3 due to its high film quality and good interfacial energy level matching, making it more suitable as the bottom interface modification material for the perovskite light-absorbing layer 4. The perovskite light-absorbing layer 4, disposed above the second hole transport layer 3, is a wide-bandgap organic-inorganic hybrid perovskite, preferably composed of C. S0.05 MA 0.15 FA 0.80 Pb(I 0.75 Br 0.25 3. The thickness is 440-550 nm. This perovskite film has a high light absorption coefficient and a long carrier diffusion length, making it suitable as the absorber layer of the top cell in a perovskite / crystalline silicon tandem solar cell. Electron transport layer 6 is used to collect and conduct photogenerated electrons, preferably using PCBM or C... 60 The electron transport layer 6 has a thickness of 200-250 nm. This layer forms a heterojunction interface with the perovskite light-absorbing layer 4, enabling directional electron transport. A hole-blocking layer 7 is disposed above the electron transport layer 6. Its material is either copper bath electrode (BCP) or tin dioxide deposited by ALD. It blocks holes and inhibits the migration of ions from the metal electrode 8 to the perovskite light-absorbing layer 4, thereby improving device stability. Electrode 8 is located at the top of the device, serving as the back electrode to collect electrons and output them to the external circuit. Its material is preferably silver or gold, with a thickness of 80-110 nm.

[0025] A bimolecular modification layer 5 is disposed between the perovskite light-absorbing layer 4 and the electron transport layer 6, connecting the two layers. The bimolecular modification layer 5 is composed of a first organic molecule and a second organic molecule, achieving synergistic passivation and energy level modulation of the interface. The first organic molecule is a field-effect passivation molecule, specifically 1,3-propanediamine hydroiodate (PDADI). This molecule establishes a stable field-effect modulation environment in the interface region through its inherent charge characteristics, thereby improving the energy level distribution and suppressing nonradiative recombination of charge carriers at the interface. Simultaneously, its amino group can interact with uncoordinated Pb on the surface of the perovskite light-absorbing layer 4. 2+ Interfacial interactions occur to further stabilize the interfacial structure, thereby increasing the open-circuit voltage of the battery. The second organic molecule is a chemical passivation molecule, specifically 3,4,5-trifluoroaniline hydrobromide (345FPhABr), whose molecule contains the halogen ion Br. — It can fill the halogen vacancies on the surface of perovskite films, and the amino groups on the molecules can interact with uncoordinated Pb. 2+The formation of a coordination structure reduces the density of interface defect states; simultaneously, the strong hydrophobicity of the polyfluorinated substituents helps improve the interface's resistance to moisture and environmental stability. Through the synergistic effect of the above-mentioned field-effect passivation and chemical passivation, the bimolecular modification layer 5 can enhance the interfacial bonding force between the perovskite light-absorbing layer 4 and the electron transport layer 6, reduce interface defect states, optimize energy level arrangement, and thus improve the efficiency of carrier extraction and transport.

[0026] Two types of molecules coexist within the bimolecular modification layer 5, and are uniformly arranged in both the thickness and in-plane directions, forming a composite molecular arrangement structure supported by different molecular characteristics at the interface region. The coexistence of the bimolecules at the interface results in a continuous, dense, and molecularly oriented thin-layer morphology on the surface of the bimolecular modification layer 5, which can conform to the microscale undulations of the perovskite light-absorbing layer 4, covering the gaps between perovskite grains and creating a smooth and complete contact morphology. The bimolecular modification layer 5 has a thickness of 1-5 nm, belonging to the nanoscale molecular thin-layer structure, forming a stable interfacial intermediate layer between the perovskite light-absorbing layer 4 and the electron transport layer 6. It possesses good interfacial integrity and compactness, providing a uniform surface for the deposition of the electron transport layer 6. Due to the density and orientation characteristics of the surface molecular arrangement, the bimolecular modification layer 5 can also improve the hydrophobicity of the interface region to a certain extent, weaken the tendency of the perovskite light absorption layer 4 to adsorb water molecules, thereby reducing the risk of external water and oxygen penetrating into the perovskite film along the interface channel.

[0027] In practical applications, when the device is exposed to light, electrons generated in the perovskite light-absorbing layer 4 begin to migrate towards the interface region. As electrons approach the surface of the perovskite light-absorbing layer 4, the charge-regulating environment formed by the first organic molecule at the interface makes the local potential of the interface region more even, facilitating smooth electron arrival at the interface and reducing the recombination probability during the initial contact process. As electrons continue to approach the bimolecular modification layer 5, the second organic molecule, through its chemical repair effect on surface defects, makes the interface contact region more uniform and stable, thus providing a better structural basis for electrons to cross the interface and enter the electron transport layer 6. The regulating effect of the first organic molecule on the interface potential environment and the improvement of the interface structural quality by the second organic molecule are spatially continuous, making the electron migration conditions in the interface region more consistent and jointly supporting the cross-interface electron transport process during actual device operation.

[0028] Example 2: This application also proposes a method for preparing a bimolecular synergistic interface-modified perovskite solar cell, such as... Figure 2 As shown, the method includes the following steps: Step 1: Substrate 1 Pretreatment; Patterned ITO conductive glass was selected as substrate 1 and ultrasonically cleaned sequentially in deionized water, acetone, isopropanol, and anhydrous ethanol solutions for 15-20 minutes each time. After cleaning, the surface of substrate 1 was dried with nitrogen and then placed in a 50W plasma cleaner for 3-5 minutes to keep the surface of substrate 1 clean and have good wettability, which is conducive to subsequent thin film formation.

[0029] Step 2: Prepare the first hole transport layer 2; apply NiO x Powder by mass to volume ratio (e.g., 10 mg NiO) x NiO powder (1 mL deionized water) was prepared. x The dispersion was prepared and ultrasonically treated for several minutes to obtain a uniform dispersion system. The pretreated ITO substrate 1 was placed on a spin coater, and an appropriate amount of NiO was dropped onto its surface. x The dispersion was spin-coated at 3000-4000 rpm for 20-30 seconds to form a uniform thin film. The spin-coated substrate 1 was then annealed on a hot plate at 100-150℃ for 5-15 minutes to allow the NiO to harden. x The thin film solidifies and forms a dense first hole transport layer 2.

[0030] Step 3: Prepare the second hole transport layer 3; dissolve 4PADCB in anhydrous ethanol to prepare a solution with a mass concentration of 0.3-0.8 mg / mL, and stir until completely dissolved. Add the NiO obtained in step 2... x / ITO substrate 1 was placed in a nitrogen glove box, and an appropriate amount of 4PADCB solution was dropped onto its surface. The substrate was then spin-coated at 3500-4500 rpm for 20-40 seconds to allow it to adhere to the NiO substrate. x A uniformly covered molecular layer is formed on the surface of the first hole transport layer 2. After spin coating, it is heated at 90-110℃ for 5-15 minutes to promote the formation of a self-assembled monolayer, thereby obtaining the second hole transport layer 3.

[0031] Step 4: Prepare perovskite light-absorbing layer 4; mix CsI, MABr, FAI, PbI2 and PbBr2 according to C S0.05 MA 0.15 FA 0.80 Pb(I 0.75 Br 0.25After weighing the stoichiometric proportions of step 3, add it to a mixed solvent of DMF and DMSO (volume ratio 4:1) to prepare a perovskite precursor solution with a concentration of 1.3-1.6 mol / L. Stir the resulting solution at room temperature until completely dissolved, and filter it through a 0.22 μm polytetrafluoroethylene (PTFE) membrane to obtain a uniform and transparent precursor solution. Place the structure obtained in step 3 on a spin coater, drop an appropriate amount of the precursor solution onto its surface, and form a perovskite wet film using a two-step spin coating method. The first spin coating speed is 800-1200 rpm, and the spin coating time is 5-10 s; the second spin coating speed is 4500-5500 rpm, and the spin coating time is 25-35 s. At the end of the second spin coating step (4-8 s before the end), add chlorobenzene as an anti-solvent to induce the crystallization process and promote film formation. After spin coating, transfer it to a heating stage at 90-110℃ for annealing for 10-25 min to allow the perovskite film to crystallize and solidify. After annealing, the material is naturally cooled to room temperature to obtain a perovskite light-absorbing layer 4 with a thickness of 440-550 nm.

[0032] Step 5: Prepare the bimolecular modification layer 5. Dissolve 1,3-propanediamine hydroiodate in isopropanol (IPA) to prepare a solution with a mass concentration of 0.5-2 mg / mL; dissolve 3,4,5-trifluoroaniline hydrobromide in IPA to prepare a solution with a mass concentration of 0.5-1 mg / mL. IPA has good solubility for both types of organic salts and a moderate evaporation rate, which is beneficial for forming a uniform and continuous interface layer. At the same time, IPA has weak solubility for the perovskite film, which can avoid damaging the underlying structure, thus ensuring the controllability and stability of the interface modification process. After the two solutions are stirred until completely dissolved, they are mixed according to a specific mass ratio to obtain a bimolecular mixed solution. Place the perovskite light absorption layer 4 obtained in step 4 on a spin coater, drop an appropriate amount of the bimolecular mixed solution onto its surface, and spin coat at a speed of 4500-5500 rpm for 20-40 s to allow the two types of molecules to spread uniformly on the perovskite surface and form an initial interface distribution. After spin coating, anneal at 90-110℃ for 3-8 minutes to promote the synergistic arrangement of the two types of molecules in the interfacial region and form a continuous molecular thin-film structure. Preferably, a two-step annealing method is used: first, low-temperature pre-annealing at 60-80℃ for 1-3 minutes to promote stable solvent evaporation and uniform spreading; then, high-temperature annealing at 100-110℃ for 2-5 minutes to further densify and smooth the interfacial thin film. After annealing, pure isopropanol solvent can be spin-coated again under the same spin-coating conditions (e.g., 4500-5500 rpm, 20-40 s) to remove unbound or accumulated excess molecules on the interface, ensuring that the surface of the bimolecular modified layer 5 maintains a uniform, dense, and thickness-controllable film morphology; low-power ultraviolet irradiation treatment can also be performed, such as irradiation with a 365nm light source for 20-60 s, to improve the surface energy distribution of the interfacial thin film and enhance its smoothness and coverage uniformity, thereby obtaining a better bimolecular modified layer 5.

[0033] In this embodiment, the mass ratio of PDADI solution to 345FPhABr solution is 1:1 to 3:1. By adjusting the ratio of the two types of molecules, a synergistic relationship between field effect regulation and chemical passivation can be achieved in the interfacial region, ensuring a suitable matching state for interfacial energy level regulation, defect repair, and thin-layer continuity during deposition. When the PDADI ratio is too low, the interfacial charge regulation capability is insufficient, leading to an increased probability of carrier recombination near the interface; while when the 345FPhABr ratio is too high, the interfacial region is prone to molecular stacking, affecting the uniformity of molecular arrangement and thus reducing the stability of the bimolecular synergistic effect. Preferably, when the mass ratio of PDADI solution to 345FPhABr solution is 2:1, a better overall effect can be achieved in terms of film uniformity, molecular arrangement stability, and interfacial regulation capability, ensuring a balance between interfacial charge regulation capability and defect passivation capability.

[0034] Furthermore, a small amount of DMF solvent is added during the preparation of the bimolecular mixed solution to adjust the polarity and volatility of the solution. DMF has high polarity, which enhances the dispersion uniformity of the two types of organic salts in the mixed system, making it easier for the molecules to achieve a uniform initial interfacial coverage during spin coating. Moreover, the low volatility of DMF prolongs the residence time of the solution on the perovskite surface during spin coating, promoting the rearrangement of the two types of molecules in the interfacial region and enhancing the density and continuity of the interfacial layer. The appropriate addition of DMF does not damage the surface structure of the perovskite light-absorbing layer 4, but rather helps to form a more regular interfacial thin layer during spin coating, thereby further optimizing the structural quality of the bimolecular modification layer 5.

[0035] Step 6: Prepare electron transport layer 6; Place the structure obtained in step 5 under a patterned mask, and deposit C on the surface of the bimolecular modified layer 5 by thermal evaporation. 60 This forms electron transport layer 6. C 60 The vapor deposition thickness is 20-30 nm, preferably 25 nm. A stable evaporation rate is maintained during the evaporation process to obtain a uniform and dense electron transport layer 6 thin film.

[0036] Step 7: Prepare the hole-blocking layer; the C formed in step 6 60 A BCP film is deposited on the thin film using a thermal evaporation method to serve as a hole-blocking layer. The evaporation thickness of the BCP is 5-10 nm, preferably 7 nm. This hole-blocking layer is used to construct an electron-selective structure and suppress direct contact between the metal electrode material and the underlying interface.

[0037] Step 8: Fabrication of metal electrode 8; A patterned silver electrode 8 is formed on the surface of the hole blocking layer by thermal evaporation. The silver deposition thickness is 80-110 nm, preferably 100 nm. During evaporation, the electrode 8 region is defined by a mask to match the device structure and complete the final electrode 8 construction, thereby obtaining a perovskite solar cell with bimolecular synergistic modification.

[0038] To verify the interface modulation effect of the bimolecular modification layer 5 described in this application, two sets of comparative experiments were set up in this embodiment. The device whose interface was modified using a mixture of 1.0 mg / mL PDADI solution and 0.5 mg / mL 345FPhABr solution was designated as the experimental group; the device whose interface was modified only using 1.0 mg / mL PDADI solution without adding 345FPhABr was designated as the control group. Both groups of devices maintained the same fabrication conditions for the perovskite light-absorbing layer 4, electron transport layer 6, and other processes, differing only in the interface modification method, to compare the impact of different interface modification strategies on device performance and interface characteristics.

[0039] After the two sets of devices were fabricated, their photovoltaic performance and spectral response were tested, and the results were as follows: Figure 3 , Figure 4 .in, Figure 3 The graph shows a comparison of the JV curves of the experimental and control groups, using an irradiation intensity of 100 mW / cm². 2 The solar simulator (AM1.5G, standard silicon cell calibration) was tested using data collected by a digital source meter under conditions of a scan range of 1.26V to -0.2V and a step size of 0.2V. Figure 4 The incident quantum efficiency (EQE) spectrum of the corresponding device was measured using a solar cell quantum efficiency testing system (calibrated with a standard silicon detector), and the short-circuit current density was calculated using EQE integration. All the above tests were conducted in an atmospheric environment and at room temperature.

[0040] from Figure 3 It can be seen that, compared with the control group devices modified only with PDADI, the experimental group devices modified with bimolecular synergistic modification exhibit higher photovoltaic performance. The fill factor (FF) and power conversion efficiency (PCE) of the control group devices are 77.93% and 19.55%, respectively, and the open-circuit voltage (V) is... OC The voltage was 1.179V; while the FF of the experimental group devices increased to 83.41%, PCE increased to 22.46%, and V... OC The voltage reached 1.222V. This result demonstrates that the introduction of the bimolecular modification layer 5 at the interface improves the interfacial contact quality, reduces nonradiative recombination, and enhances the interfacial charge transport efficiency, thereby improving the overall photovoltaic performance.

[0041] from Figure 4 It can be seen that the incident light quantum efficiency spectra of both the experimental and control groups exhibit stable spectral responses. The left ordinate corresponds to the EQE variation with wavelength, showing that the experimental group demonstrates improved quantum efficiency in the long wavelength region of 650-720 nm compared to the control group, indicating that the bimolecular modification layer 5 can improve carrier transport and collection efficiency at the interface. The right ordinate corresponds to the short-circuit current density curve obtained by integrating the EQE. The integration result shows that the short-circuit current density of the experimental group device is 21.09 mA / cm². 2 The short-circuit current density of the control group device was 21.02 mA / cm². 2 Both results are consistent with the corresponding JV curve test results, indicating that the electrical test results of the device have good reliability.

[0042] Experimental results show that, compared with the control group device that only uses PDADI to modify the interface, the bimolecular modification layer 5 used in this embodiment can improve the interface quality and enable the device to obtain higher photovoltaic performance, thus verifying the effectiveness of the interface modification strategy of this application.

[0043] In summary, this application improves the interface contact quality and creates a smoother interface energy level distribution by introducing a bimolecular modification layer 5 at the interface between the perovskite light-absorbing layer 4 and the electron transport layer 6, which is beneficial for the extraction and transport of photogenerated carriers. By using two separately dissolved organic molecules to form a mixed modification solution, a more uniform and continuous thin-layer structure can be obtained at the interface, thereby reducing the defect state density on the perovskite film surface. The interface modification method of this invention improves the optoelectronic performance of the device while also enhancing its operational stability, showing promising application prospects.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bimolecular synergistic interface-modified perovskite solar cell, comprising a substrate, a first hole transport layer, a second hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole-blocking layer, and an electrode, stacked sequentially, characterized in that: A bimolecular modification layer composed of a first organic molecule and a second organic molecule is disposed between the perovskite light-absorbing layer and the electron transport layer.

2. The perovskite solar cell with bimolecular synergistic interface modification according to claim 1, characterized in that: The first organic molecule and the second organic molecule are mixed and distributed within the thickness range of the bimolecular modified layer.

3. The perovskite solar cell with bimolecular synergistic interface modification according to claim 2, characterized in that: The first organic molecule has a polar group that regulates the interfacial charge environment, and the second organic molecule has a functional group that binds to interfacial defect sites.

4. The perovskite solar cell with bimolecular synergistic interface modification according to claim 3, characterized in that: The first organic molecule is 1,3-propanediamine hydroiodide salt, and the second organic molecule is 3,4,5-trifluoroaniline hydrobromide.

5. A method for fabricating a perovskite solar cell with bimolecular synergistic interface modification, comprising sequentially fabricating a first hole transport layer, a second hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole-blocking layer, and an electrode on a substrate, characterized in that: Before preparing the electron transport layer, a first organic molecular solution and a second organic molecular solution are mixed and applied to the surface of the perovskite light-absorbing layer, and then annealed to form a bimolecular modified layer.

6. The method for preparing a perovskite solar cell with bimolecular synergistic interface modification according to claim 5, characterized in that: The mass ratio of the first organic molecular solution to the second organic molecular solution is 1:1 to 3:

1.

7. The method for preparing a perovskite solar cell with bimolecular synergistic interface modification according to claim 5 or 6, characterized in that: The mixed solution is applied by spin coating at a speed of 4000-6000 rpm for 20-40 seconds.

8. The method for preparing a perovskite solar cell with bimolecular synergistic interface modification according to claim 7, characterized in that: The annealing temperature is 80-120℃, and the annealing time is 3-10 min.

9. The method for preparing a perovskite solar cell with bimolecular synergistic interface modification according to claim 5, characterized in that: The solvent for both the first organic molecular solution and the second organic molecular solution is isopropanol.

10. The method for preparing a perovskite solar cell with bimolecular synergistic interface modification according to claim 9, characterized in that: The solvent also contains DMF.

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