A low-dimensional halide solar cell based on molecular regulation and a preparation method thereof

Abstract

The application discloses a low-dimensional halide solar cell based on molecular regulation and a preparation method thereof, and belongs to the technical field of battery devices.The performance of the battery device is regulated by introducing 4FTBA into a precursor solution.The scheme in the application regulates at the molecular level, optimizes the thin film crystallization quality and reduces the defect state density, and a three-dimensional interpenetrating network is constructed by combining a nano-imprinting technology, so that the micro-morphology of the thin film and the interface structure are accurately regulated while the process is simplified and the cost is reduced, the photon capture efficiency and the carrier longitudinal transport capacity are simultaneously improved, and the photoelectric conversion efficiency and the working stability of the device are significantly enhanced.

Description

Technical Field

[0001] This invention belongs to the field of battery device technology, specifically relating to a low-dimensional halide solar cell based on molecular regulation and its preparation method. Background Technology

[0002] With the rapid development of next-generation photovoltaic technology, metal halide semiconductors have become one of the most promising optoelectronic material systems due to their excellent photoelectric performance and low-cost solution processing advantages. The photoelectric conversion efficiency of traditional three-dimensional metal halide solar cells has now exceeded 26%. However, their commercialization process has always been constrained by the shortcomings of intrinsic stability, such as moisture-induced degradation, accelerated ion migration, and phase separation under long-term heat and light irradiation, which seriously restricts the long-term service life of the devices.

[0003] To overcome the stability bottleneck of three-dimensional metal halide materials, low-dimensional (two-dimensional or quasi-two-dimensional) metal halide materials have emerged. These materials, with their unique layered quantum confinement structure, exhibit significantly suppressed ion migration, lower surface defect states, tunable band gaps, and excellent moisture and heat resistance, demonstrating enormous application potential to replace three-dimensional systems. However, the photoelectric conversion efficiency of current low-dimensional metal halide solar cells consistently lags behind that of three-dimensional devices. The efficiency of high-efficiency devices reported in the industry generally hovers around 23%, making further breakthroughs difficult. The core reason for this performance gap lies in the anisotropy of carrier transport in the low-dimensional framework, the non-uniform multi-quantum-well phase distribution, and severe non-radiative recombination losses at thin film interfaces and grain boundaries.

[0004] To overcome the industry challenge of limited carrier transport in low-dimensional metal halides, integrating low-dimensional materials with advanced micro / nano device structures has become a mainstream technological direction. Among these, ordered PN vertically interpenetrating heterojunctions constructed using nanoimprint lithography have proven to be a highly effective optimization strategy. This structure significantly expands the interface charge separation area by interpenetrating p-type metal halides and n-type semiconductor materials in three-dimensional space, greatly shortening the carrier transport distance to the corresponding electrodes. Simultaneously, the periodic patterned structure improves the device's optical field distribution, synergistically promoting charge separation, extraction, and collection efficiency. Existing patent CN122161324A has proposed a scheme for constructing such vertically interpenetrating heterojunctions in a three-dimensional all-cation-doped perovskite system, achieving a photoelectric conversion efficiency exceeding 26%. However, this scheme is only suitable for three-dimensional perovskite systems. The three-dimensional material itself lacks an organic spacer layer to form a hydrophobic barrier, and after 1000 hours of continuous maximum power point tracking, the efficiency margin is only 37%. Long-term operational stability cannot meet industrialization requirements, and it does not perform any targeted optimization for the characteristics of low-dimensional metal halides.

[0005] Subsequently, the industry further developed a technical route that combines molecular regulation with nanoimprint morphology engineering, such as the publicly disclosed low-dimensional metal halide solar cell technology. This scheme uses thiomorpholine hydroiodide (TMI) as a molecular regulation additive. Through the coordination of sulfur atoms with Pb and the hydrogen bonding of amine groups with iodide ions, it achieves basic crystallization kinetics regulation and defect passivation. The final device achieved a photoelectric conversion efficiency of 24.27%, and the efficiency residue reached 84% after 1000 hours of maximum power point tracking. However, the molecular regulation effect of this scheme is limited to basic nucleation rate adjustment and simple defect passivation. It still does not specifically address the core pain points of low-dimensional metal halides, such as disordered enrichment of multiple n phases, severe obstruction of vertical carrier transport caused by random crystal orientation, and insufficient energy level matching. It also cannot simultaneously improve the light capture efficiency of low-dimensional devices through molecular structure characteristics, making it difficult to break through the efficiency ceiling of low-dimensional systems while ensuring stability advantages.

[0006] The aforementioned existing technologies generally optimize "material crystallization regulation" and "vertical heterojunction structure construction" as two relatively independent processes. They consistently lack a deep, synergistic regulation mechanism for the crystallization kinetics, quantum well phase distribution, crystal orientation, defect passivation, and nanoimprinting process adaptability of low-dimensional metal halides. Simply using ordinary additives for simple defect passivation or altering the macroscopic morphology of the active layer through nanoimprinting cannot simultaneously solve common industry challenges in low-dimensional metal halides, such as the disordered coexistence of multiple n-phases, limited longitudinal carrier transport, enrichment of interface defects, and insufficient adaptability to nanoimprinting processes. Therefore, developing a high-performance low-dimensional metal halide solar cell based on a novel targeted molecular regulation strategy that can achieve multi-dimensional performance synergistic optimization is a critical technological need urgently needing to be addressed in this field. Summary of the Invention

[0007] This invention provides a low-dimensional halide solar cell based on molecular regulation and its preparation method, thereby overcoming the deficiencies in the prior art.

[0008] To achieve the above objectives, the technical solution adopted by this invention is to provide a method for preparing a low-dimensional halide solar cell based on molecular regulation, comprising the following steps: S1: Lead iodide, methylammonium iodide, guanidine iodide and 4-(trifluoromethyl)thiobenzamide are co-dissolved in a mixed solvent to obtain a halide precursor solution; the mixed solvent is obtained by mixing N,N-dimethylformamide and dimethyl sulfoxide; S2: Spin-coat the halide precursor solution onto a glass substrate with a double hole transport layer, and after removing the solvent, form a precursor film on the double hole transport layer. S3: The precursor film is imprinted using a sapphire substrate wafer template to form a periodic hole structure on the precursor film, followed by annealing. S4: N-type semiconductors and P-type semiconductors are blended in chlorobenzene to obtain a mixed solution; then the mixed solution is spin-coated onto the precursor film after imprinting and annealing to form an organic layer; S5: Deposit BCP and silver electrode sequentially on the organic layer to obtain the final product.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide in the mixed solvent is 5~15:1.

[0011] Furthermore, the ratio of lead iodide (PbI2), methyl ammonium iodide (MAI), guanidine iodide (GAI), and 4-(trifluoromethyl)thiobenzamide (4FTBA) to the mixed solvent is 690~700mg: 230~240mg: 6~7mg: 0.05~0.2mg: 1mL.

[0012] Furthermore, in S2, the glass substrate with a double hole transport layer consists of, from bottom to top, a glass substrate, a nickel oxide thin film layer, and a [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) thin film layer.

[0013] Furthermore, the glass substrate with the double hole transport layer is prepared by the following steps: S21: Dissolve nickel oxide in water to obtain a solution with a concentration of 5-15 mg / mL. Then add hydrogen peroxide to the obtained solution and mix thoroughly to obtain a nickel oxide dispersion. The molar percentage of hydrogen peroxide in the obtained nickel oxide dispersion is 35-50 mol.%. S22: Spin-coat the nickel oxide dispersion onto the pretreated glass substrate at a speed of 1500~3000 rpm for 30~50 s, then anneal at 100~150℃ for 15~30 min to form a nickel oxide film on the glass substrate; subsequently, spin-coat a MeO-2PACz / ethanol solution with a concentration of 0.1~1 mg / mL onto the nickel oxide film at a speed of 2500~4000 rpm for 20~40 s, then anneal at 100~120℃ for 15~30 min to obtain the final product.

[0014] Furthermore, before spin-coating the halide precursor solution, S2 first spin-coated a phenylethyl ammonium iodide / ethanol solution with a concentration of 0.5~2 mg / mL onto the double hole transport layer at a spin-coating speed of 4000 rpm and a spin-coating time of 20 s.

[0015] Furthermore, in S2, the halide precursor solution is spin-coated at 800 rpm for 8 seconds, and then at 5000 rpm for 30 seconds; the solvent is removed by adding anisole as an anti-solvent when the second stage of spin-coating the precursor solution has been carried out for 20 seconds.

[0016] Furthermore, the imprinting pressure in S3 is 110~150 bar, the imprinting time is 40~80 s; the annealing temperature is 100~120℃, and the annealing time is 50~70 min.

[0017] Furthermore, the solutes in the mixed solution in S4 are D18-Cl, PY-IT, and PC. 71 BM, D18-Cl, PY-IT and PC 71 The mass ratio of BM is 1:5:4; the concentration of the mixed solution is 8~12 mg / mL.

[0018] The present invention also discloses a low-dimensional halide solar cell based on molecular regulation prepared by the above preparation method.

[0019] The beneficial effects of this invention are: This invention aims to address the complex phase distribution, restricted charge transport, enhanced exciton effects, and interface defects in low-dimensional halides, while simultaneously resolving the contradiction between sufficient light absorption and efficient charge collection that traditional planar or quasi-planar heterojunction structures struggle to achieve simultaneously. To this end, this invention proposes a molecularly controlled fabrication scheme that physically integrates the functional advantages of wide and narrow bandgap light-absorbing materials, eliminating the need for any intermediate connecting layer. The scheme in this invention optimizes the crystallinity of the thin film and reduces the defect state density through molecular-level control. Combined with nanoimprinting technology to construct a three-dimensional interpenetrating network, it simplifies the process, reduces costs, and achieves precise control over the microstructure and interface structure of the thin film, thereby simultaneously improving photon capture efficiency and longitudinal carrier transport capability, significantly enhancing the photoelectric conversion efficiency and operational stability of the device. Specifically: This invention introduces 4-(trifluoromethyl)thiobenzamide (4FTBA) in a precursor solution. The 4FTBA molecule contains multiple characteristic functional groups, including trifluoromethyl (-CF3), thiocarbonyl (C=S), and amino (-NH2). The thioamide structure (C=S) used in this invention has significantly stronger coordination ability compared to the conventional amide structure (C=O), which stems from the deep mechanism of the hard-soft acid-base theory (HSAB): Pb 2+ Thioamides are soft acids, while the sulfur atom in thioamides is a soft base. A soft-soft affinity interaction forms between them, resulting in a stronger and more stable coordination bond. In contrast, the oxygen atom in conventional amides is a hard base, which interacts with Pb. 2+The "hard-soft" matching is poor, and the coordination effect is relatively weak. Therefore, the thiocarbonyl group in 4-(trifluoromethyl)thiobenzamide can react with Pb. 2+ This process forms stronger coordination bonds, more effectively anchoring the crystal nucleus surface in the early stages of crystallization. It also forms intermediate adducts with PbI₂ or lead halide complexes in the precursor solution, slowing down the rapid formation of the Pb-I framework, reducing the nucleation rate, regulating crystal nucleation and growth kinetics, and suppressing the rapid formation of non-uniform low-n phases, thus optimizing the n-phase distribution in low-dimensional metal halides. Simultaneously, it passesivates uncoordinated Pb in the passivation film. 2+ Deep-level defects near halogen vacancies reduce trap-assisted nonradiative recombination. Furthermore, the synergistic coordination of amino groups further enhances the binding affinity between the molecule and the metal halide framework, forming a multi-site synergistic anchoring effect, thus significantly outperforming single or weakly coordinated additives in terms of crystallization control efficiency and defect passivation depth. The strong electron-withdrawing effect of trifluoromethyl (-CF3) can regulate molecular polarity, enhance the dipole-dipole interaction between the additive and the metal halide framework, change the grain boundary energy state and band bending, and make the energy levels of each layer of the device more matched. In addition, the introduction of trifluoromethyl imparts a lower surface energy to the film surface, forming a hydrophobic barrier that effectively blocks water and oxygen erosion, significantly improving the long-term stability of the film under environmental conditions. 4FTBA has a planar aromatic structure, which can form a relatively ordered molecular layer at grain boundaries or film surfaces through intermolecular π-π interactions, thereby reducing grain boundary surface energy, promoting lateral grain growth, reducing pinholes and disordered grain boundaries, improving the preferred orientation of low-dimensional perovskite crystals, and solving the problem of blocked carrier transport in the vertical direction in low-dimensional metal halides. Therefore, the 4-(trifluoromethyl)thiobenzamide in this invention is not simply used as a defect passivation additive in traditional three-dimensional metal halides, but rather it addresses the unique problems in low-dimensional metal halides such as the coexistence of multiple n phases, inhomogeneous quantum well structures, interlayer interface defects, and limited carrier transport, achieving multifunctional molecular regulation of crystal growth control, defect passivation, and stability enhancement.

[0020] Furthermore, the technical solution of this invention employs nanoimprinting technology to construct a porous array structure with specific periodicity and depth when the thin film is in a partially crystalline state, and fills it with organic semiconductor material, ultimately forming a highly efficient vertically interfacial heterojunction. This structure significantly increases the interfacial contact area, shortens the longitudinal transport path of charge carriers to the electrodes, and enhances the light-trapping effect within the active layer.

[0021] Furthermore, the molecular regulation of 4-(trifluoromethyl)thiobenzamide in this invention not only independently optimizes the film quality but also forms a deep synergy with the nanoimprinting process: this additive, in a partially crystalline state, endows the film with suitable flexibility and plasticity, enabling the porous pattern to be transferred uniformly and completely during nanoimprinting without inducing microcrack propagation—a process compatibility advantage that is difficult to achieve with conventional additives. Simultaneously, molecular-level regulation also endows the film with excellent environmental stability and good process repeatability, providing a feasible path to realize novel photovoltaic devices that combine high conversion efficiency, excellent stability, and a simple fabrication process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the solar cell of the present invention; Figure 2 The JV curves are for the solar cells prepared in Example 1 and Comparative Example 2; Figure 3 The X-ray diffraction patterns of the precursor films prepared in Example 1 and Comparative Example 2 are shown. Figure 4 The UV absorption spectra of the precursor films prepared in Example 1 and Comparative Example 2 are shown. Figure 5 The fluorescence emission spectra of the precursor films prepared in Example 1 and Comparative Example 2 are shown. Figure 6 The time-resolved fluorescence emission spectra of the precursor films prepared in Example 1 and Comparative Example 2 are shown. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0024] Example 1

[0025] A low-dimensional halide solar cell based on molecular regulation, the structure of which is as follows: Figure 1 As shown; the solar cell in this embodiment is manufactured through the following steps: S1: Nickel oxide (NiO) x The nickel oxide was dissolved in water to obtain a solution with a concentration of 10 mg / mL. Hydrogen peroxide was added to the solution (after adding hydrogen peroxide, the molar percentage of hydrogen peroxide in the solution was 40 mol.%). The solution was then sonicated at low temperature for 30 min and filtered through a 0.22 μm polytetrafluoroethylene filter membrane to obtain a nickel oxide dispersion. S2: After being washed with detergent and water, the FTO substrate was sequentially immersed in deionized water, acetone, and isopropanol, and ultrasonicated for 15 minutes each, followed by cleaning with a nitrogen gun; then it was placed in an ultraviolet ozone cleaner and irradiated with ultraviolet light at a wavelength of 185 nm for 20 minutes; then a nickel oxide dispersion was spin-coated onto the pretreated substrate and subjected to a first annealing treatment to form a nickel oxide film on the substrate. The spin-coating speed of the nickel oxide dispersion was 2000 rpm, the spin-coating time was 40 s, the temperature of the first annealing treatment was 120℃, and the first annealing time was 20 minutes; then a MeO-2PACz / ethanol solution was spin-coated onto the nickel oxide film and subjected to a second annealing treatment to form a double hole transport layer on the substrate; the spin-coating speed of the MeO-2PACz / ethanol solution was 3000 rpm, the spin-coating time was 30 s, the concentration of the MeO-2PACz / ethanol solution was 0.5 mg / mL, and the temperature of the second annealing treatment was 110℃, and the second annealing time was 20 minutes. S3: Lead iodide, methylammonium iodide, guanidine iodide, and 4-(trifluoromethyl)thiobenzamide were co-dissolved in a mixed solvent and stirred at room temperature for 8 hours. The mixture was then filtered through a 0.22 μm polytetrafluoroethylene membrane to obtain a halide precursor solution. The mixed solvent was composed of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 10:1. The feed-to-liquid ratio of lead iodide, methylammonium iodide, guanidine iodide, and 4-(trifluoromethyl)thiobenzamide to the mixed solvent was 691.5 mg: 238.5 mg: 6.1 mg: 0.1 mg: 1 mL. S4: A wetting solution is spin-coated onto the double-layer hole transport layer to improve wettability. The spin-coating speed is 4000 rpm and the spin-coating time is 20 s. The wetting solution is a 1 mg / mL phenylethyl ammonium iodide (PEAI) / ethanol solution. Then, a halide precursor solution is spin-coated onto the double-layer hole transport layer. The spin-coating method is as follows: first, spin-coat at 800 rpm for 8 s (first stage), then spin-coat at 5000 rpm for 30 s (second stage). During the second stage of spin-coating the halide precursor solution, anisole is added dropwise as an anti-solvent while spin-coating to accelerate solvent removal and form a precursor film on the double-layer hole transport layer (vacuum treatment can be applied to accelerate film formation). S5: The precursor film is imprinted using a sapphire substrate wafer template at a pressure of 120 bar for 60 seconds, which partially solidifies the precursor film and transfers a porous pattern. After imprinting, a periodic hole structure is formed on the precursor film with a hole spacing of approximately 800 nm and a hole depth of approximately 60 nm. Then, an annealing process is performed at a temperature of 110 °C for 60 minutes. S5: Combine D18-Cl, PY-IT, and PC71 BM was mixed with chlorobenzene at a mass ratio of 1:5:4 to obtain a mixed solution with a concentration of 10 mg / mL; then the mixed solution was spin-coated onto the precursor film after embossing and annealing at a speed of 2000 rpm (spin-coating time was 30 s) to form an organic layer. S6: A 6nm thick BCP (bath copper spirit) is deposited on the organic layer by thermal evaporation as an electron transport layer, and then a 120nm thick silver electrode is deposited to obtain a low-dimensional halide solar cell based on molecular regulation.

[0026] Example 2

[0027] A low-dimensional halide solar cell based on molecular regulation is prepared by adjusting the ratio of lead iodide, methyl ammonium iodide, guanidine iodide and 4-(trifluoromethyl)thiobenzamide to the mixed solvent in S3 to 690mg:230mg:6mg:0.05mg:1mL, compared with Example 1; the other conditions are the same as in Example 1.

[0028] Example 3

[0029] A low-dimensional halide solar cell based on molecular regulation is prepared by adjusting the ratio of lead iodide, methyl ammonium iodide, guanidine iodide and 4-(trifluoromethyl)thiobenzamide to the mixed solvent in S3 to 700mg:240mg:7mg:0.2mg:1mL, compared with Example 1; the other conditions are the same as in Example 1.

[0030] Comparative Example 1 A solar cell with a P / N vertically interleaved heterojunction structure is prepared according to the preparation process described in the patent "A solar cell with a P / N vertically interleaved heterojunction structure and its preparation method" (202610268802.3).

[0031] Comparative Example 2 A low-dimensional halide solar cell based on molecular regulation is prepared by omitting 4-(trifluoromethyl)thiobenzamide in the halide precursor solution compared with Example 1; the other conditions are the same as in Example 1.

[0032] Comparative Example 3 A low-dimensional halide solar cell based on molecular regulation is prepared by replacing 4-(trifluoromethyl)thiobenzamide in the halide precursor solution with an equimolar amount of benzamide, compared with Example 1; the other conditions are the same as in Example 1.

[0033] Comparative Example 4 A low-dimensional halide solar cell based on molecular regulation is prepared by omitting guanidine iodide in the halide precursor solution compared with Example 1; the other conditions are the same as in Example 1.

[0034] Comparative Example 5 A low-dimensional halide solar cell based on molecular regulation is prepared in a method that differs from that in Example 1. In Example 3, the solvent in the halide precursor solution is a mixture of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1, and the other conditions are the same as in Example 1.

[0035] Experimental Example The low-dimensional halide solar cells prepared in Examples 1-3 of this invention have similar performance. Taking Example 1 as an example, the performance of the solar cell prepared by this invention will be described in detail.

[0036] The performance of the solar cells prepared in Example 1 and Comparative Example 1 was tested, and the test items and results are shown in Table 1.

[0037] Table 1. Performance comparison of solar cells obtained in Example 1 and Comparative Example 1

[0038] As can be seen from Table 1, compared with the three-dimensional system of Comparative Example 1, the low-dimensional halide film controlled by 4FTBA in this invention forms a dense hydrophobic barrier on the film surface due to the strong hydrophobic effect of trifluoromethyl groups, which greatly improves the water and oxygen barrier capacity. It completely avoids the defects of fast ion migration and poor long-term operation stability caused by the lack of a natural hydrophobic layer in three-dimensional perovskites. After 1000 hours of continuous operation, the efficiency margin jumped from 37% to 92%. At the same time, it overcomes the original shortcoming of the low-dimensional system in terms of fill factor, which is further increased from 75.7% in the TMI system to 89.2%, thus taking into account the high carrier transport capacity of the three-dimensional system and the high stability of the low-dimensional system.

[0039] Meanwhile, the 4FTBA molecular regulation and nanoimprinting process of the present invention can form a synergistic effect: 4FTBA in the partially crystalline state of the film gives the film more suitable flexibility and plasticity, the transfer integrity of the porous pattern is higher during the nanoimprinting process, there are almost no microcracks and local stress concentration problems, and the process repeatability is better than the scheme of Comparative Example 1.

[0040] The current density-voltage (JV) curves of the low-dimensional halide solar cells based on molecular regulation prepared in Example 1 (4FTBA) and Comparative Example 2 (Control) of this invention are shown below. Figure 2 As shown. From Figure 2As can be seen, the solar cell prepared in Comparative Example 2, due to the absence of 4FTBA, exhibits problems such as uneven phase distribution, limited carrier transport, and high defect density in the low-dimensional thin film, resulting in poor photoelectric performance. However, after introducing 4FTBA in Example 1 of this invention, the three core photovoltaic parameters—open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF)—are significantly improved, ultimately achieving a photoelectric conversion efficiency (PCE) of over 24%. This directly verifies the enhancement effect of the molecularly regulated synergistic nanoimprinted heterojunction scheme of this invention on the photoelectric performance of the device.

[0041] The X-ray diffraction patterns and ultraviolet absorption spectra of the precursor films prepared in Example 1 (4FTBA) and Comparative Example 2 (Control) of this invention are as follows: Figure 3 and 4 As shown. From Figure 3 As can be seen, compared to the control in Comparative Example 2 without 4FTBA, the diffraction intensity of the 100 characteristic crystal plane of the precursor film formed after introducing 4FTBA in Example 1 of this invention is significantly enhanced. This indicates that the introduction of 4FTBA effectively optimizes the crystal orientation and overall crystal quality of the low-dimensional halide, promotes the preferential growth of grains, and solves the problem of hindered longitudinal carrier transport caused by disordered crystal orientation in traditional low-dimensional films. Figure 4 As can be seen, the light absorption capacity of the film after adding 4FTBA is significantly improved in the visible to near-infrared band range of 550~900nm. This indicates that the phase distribution of low-dimensional halides is optimized after molecular regulation by 4FTBA. At the same time, combined with the light trapping effect of the periodic micro-nano structure formed by subsequent nanoimprinting, the light-harvesting capability of the whole band is improved, providing optical support for the improvement of short-circuit current density of the device.

[0042] The fluorescence emission spectra and time-resolved fluorescence emission spectra of the precursor films prepared in Example 1 (4FTBA) and Comparative Example 2 (Control) of this invention are as follows: Figure 5 and 6 As shown. From Figure 5 As can be seen, the fluorescence emission intensity of the precursor film obtained after adding 4FTBA is significantly improved compared with that obtained without adding 4FTBA. This indicates that the nonradiative recombination process inside the film is greatly suppressed after adding 4FTBA, and the defect states such as uncoordinated lead ions and halogen vacancies, which were originally nonradiative recombination centers, are effectively passivated, reducing the carrier trap recombination loss. Figure 6As can be seen, the fluorescence decay time of the precursor film after the introduction of 4FTBA is significantly longer than that of the precursor film without the addition of 4FTBA. This indicates that after molecular regulation, the carrier lifetime in the low-dimensional halide film is increased, and the carriers have more time to be transported to the heterojunction interface to complete the separation before being trapped by defects. This reduces the energy loss caused by nonradiative recombination and provides direct microscopic evidence for the improvement of the carrier collection efficiency of the device.

[0043] Furthermore, the ultraviolet photoelectron spectroscopy (UVP) spectra of the precursor films prepared in Example 1 (4FTBA) and Comparative Example 2 (Control) of this invention were tested. The test results show that after adding 4FTBA, the surface Fermi level of the low-dimensional halide P-type semiconductor film is raised, and the energy levels are more matched, which is beneficial for electron extraction. This result proves that the introduction of 4FTBA optimizes the energy level arrangement of the entire photovoltaic device, making the energy level difference between the halide light-absorbing layer and the adjacent functional layer more reasonable, effectively reducing the extraction barrier of charge carriers at the interface, which is more conducive to the smooth transport and extraction of photogenerated charge carriers, further reducing energy loss at the interface, and providing theoretical support at the energy level for improving the open-circuit voltage of the device.

[0044] The performance of the solar cells prepared in Example 1 and Comparative Examples 3-5 was tested. The test items and test results are shown in Table 2.

[0045] Table 2. Performance comparison of solar cells obtained in Example 1 and Comparative Examples 3-5

[0046] As can be seen from Table 2, replacing or omitting some components in the halide precursor solution will have an adverse effect on the performance of the resulting battery, as detailed below: Comparative Example 3, where 4FTBA was replaced with ordinary benzamide, resulted in a device with a photoelectric conversion efficiency of only 18.2%, an open-circuit voltage of 1.11V, and a residual efficiency of only 53% after 1000 hours of operation. This is because the oxygen atom in ordinary benzamide is a hard base, which reacts with the soft acid Pb. 2+ Poor coordination matching means that stable coordination adducts cannot be formed to regulate crystallization kinetics. This results in the inability to effectively passivate deep-level defects or induce preferred orientation in low-dimensional crystals. Furthermore, the lack of the hydrophobic effect of trifluoromethyl groups means that a hydrophobic barrier cannot be formed on the film surface, leading to a significant decrease in environmental stability.

[0047] Comparative Example 4 omitted guanidine iodide from the halide precursor solution, resulting in a device with a photoelectric conversion efficiency of only 11.2% and a short-circuit current density as low as 18.1 mA·cm⁻¹. -2The fill factor is less than 60%. This is because the guanidinium group in guanidine iodide is the core spacer group for constructing the low-dimensional layered quantum well structure. After its absence, the proportion of low-dimensional phase generation is less than 30%, and a stable layered hydrophobic structure cannot be formed, resulting in a significant increase in ion migration rate. At the same time, crystal growth completely loses its directionality, and a large number of charge carriers are captured at the grain boundaries, severely hindering the longitudinal transport process. The regulatory role of 4FTBA cannot be fully utilized.

[0048] Comparative Example 5, by adjusting the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide in the halide precursor solution, resulted in a final device with a photoelectric conversion efficiency of only 15.3% and an open-circuit voltage of 1.03V. This is because an excessively high DMSO content alters the coordination equilibrium of the precursor solution, leading to localized agglomeration and disordered nucleation of low-dimensional crystals during spin coating. The film flatness becomes completely uncontrolled, and even the moderating effect of 4FTBA cannot suppress the excessively rapid crystallization rate. Ultimately, the phase distribution uniformity of the film decreases significantly, and the defect density increases markedly.

[0049] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A method for fabricating low-dimensional halide solar cells based on molecular regulation, characterized in that, Includes the following steps: S1: Lead iodide, methylammonium iodide, guanidine iodide, and 4-(trifluoromethyl)thiobenzamide are co-dissolved in a mixed solvent to obtain a halide precursor solution; the mixed solvent is obtained by mixing N,N-dimethylformamide and dimethyl sulfoxide. S2: Spin-coat the halide precursor solution onto a glass substrate with a double hole transport layer, and after removing the solvent, form a precursor film on the double hole transport layer. S3: The precursor film is imprinted using a sapphire substrate wafer template to form a periodic hole structure on the precursor film, followed by annealing. S4: N-type semiconductors and P-type semiconductors are blended in chlorobenzene to obtain a mixed solution; then the mixed solution is spin-coated onto the precursor film after imprinting and annealing to form an organic layer; S5: Deposit BCP and silver electrode sequentially on the organic layer to obtain the final product.

2. The preparation method according to claim 1, characterized in that: The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide in the mixed solvent is 5~15:

1.

3. The preparation method according to claim 2, characterized in that: The ratio of lead iodide, methyl ammonium iodide, guanidine iodide, and 4-(trifluoromethyl)thiobenzamide to the mixed solvent is 690~700mg:230~240mg:6~7mg:0.05~0.2mg:1mL.

4. The preparation method according to claim 1, characterized in that: The glass substrate with a double hole transport layer described in S2 consists of, from bottom to top, a glass substrate, a nickel oxide thin film layer, and a [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid thin film layer.

5. The preparation method according to claim 4, characterized in that, A glass substrate with a double hole transport layer is prepared by the following steps: S21: Dissolve nickel oxide in water to obtain a solution with a concentration of 5-15 mg / mL. Then add hydrogen peroxide to the obtained solution and mix thoroughly to obtain a nickel oxide dispersion. The molar percentage of hydrogen peroxide in the obtained nickel oxide dispersion is 35-50 mol.%. S22: Spin-coat the nickel oxide dispersion onto the pretreated glass substrate at a speed of 1500~3000 rpm for 30~50 s, then anneal at 100~150℃ for 15~30 min to form a nickel oxide film on the glass substrate; subsequently, spin-coat a MeO-2PACz / ethanol solution with a concentration of 0.1~1 mg / mL onto the nickel oxide film at a speed of 2500~4000 rpm for 20~40 s, then anneal at 100~120℃ for 15~30 min to obtain the final product.

6. The preparation method according to claim 1, characterized in that: Before spin-coating the halide precursor solution, S2 first spin-coated a 0.5~2 mg / mL phenylethyl ammonium iodide / ethanol solution onto the double hole transport layer at a spin-coating speed of 4000 rpm for 20 s.

7. The preparation method according to claim 6, characterized in that: The method for spin-coating the halide precursor solution in S2 is to first spin-coat at 800 rpm for 8 seconds, and then spin-coat at 5000 rpm for 30 seconds; the solvent removal method is to add anisole as an anti-solvent when the second stage of spin-coating the halide precursor solution has been carried out for 20 seconds.

8. The preparation method according to claim 1, characterized in that: The imprinting pressure in S3 is 110~150 bar, and the imprinting time is 40~80 s; the annealing temperature is 100~120℃, and the annealing time is 50~70 min.

9. The preparation method according to claim 1, characterized in that: The solutes in the mixed solution described in S4 are D18-Cl, PY-IT, and PC. 71 BM, D18-Cl, PY-IT and PC 71 The mass ratio of BM is 1:5:4; the concentration of the mixed solution is 8~12 mg / mL.

10. A low-dimensional halide solar cell based on molecular regulation prepared by the preparation method according to any one of claims 1 to 9.

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