Perovskite solar cell based on 4, 6-dichloro-1, 3, 5-triazine-2-amine additive and preparation method thereof

Abstract

The invention discloses a perovskite solar cell based on a 4, 6-dichloro-1, 3, 5-triazine-2-amine additive and a preparation method of the perovskite solar cell, and belongs to the technical field of novel photovoltaic materials and devices. According to the invention, a multifunctional additive 4, 6-dichloro-1, 3, 5-triazine-2-amine with a unique molecular structure is introduced into a perovskite precursor solution, so that the perovskite solar cell with high performance and high stability is prepared. According to the present invention, the 1, 4, 6-dichloro-1, 3, 5-triazine-2-amine additive simultaneously achieves the comprehensive passivation of defects and the optimization of the crystallization process on the single molecule level through the synergistic effect of the three functional groups such as the triazine ring, the amino group and the chlorine atom, and the effect cannot be achieved by the existing single-function additive; the open-circuit voltage (Voc) and the fill factor (FF) of the prepared perovskite solar cell are remarkably improved, and higher photoelectric conversion efficiency is obtained. Meanwhile, the long-term stability (including maximum power point tracking stability and 85 DEG C thermal stability) of the device is improved by several times.

Description

Technical Field

[0001] This invention relates to the field of novel photovoltaic materials and devices, and more specifically to a perovskite solar cell based on a 4,6-dichloro-1,3,5-triazine-2-amine additive and its preparation method. Background Technology

[0002] Perovskite solar cells have become a research frontier in the photovoltaic field due to their excellent photoelectric performance and low manufacturing cost. However, their commercialization is still limited by two core issues: First, the presence of numerous crystal defects (such as lead vacancies and halogen vacancies) inside and at the interface of perovskite polycrystalline thin films leads to severe nonradiative recombination losses, limiting the improvement of device open-circuit voltage and efficiency. Second, the intrinsic instability of perovskite materials under stresses such as light, heat, and humidity, especially the migration of halide ions, can cause rapid degradation of device performance.

[0003] In the existing technology, additive engineering is one of the most effective strategies to solve the above problems. Common additives include small molecule ammonium salts (such as MACl), polymers, fullerenes and their derivatives, which mainly passivate specific defects through a single interaction (such as coordination or hydrogen bonding).

[0004] However, these additives often suffer from several drawbacks: 1. Limited functionality and poor synergy. Most additives contain only one active functional group (e.g., only amino or only halogen), and can only interact with a specific defect site in the perovskite, failing to achieve comprehensive defect passivation. 2. Limited control over the crystallization process. They lack effective guidance on crystallization kinetics, with many additives acting only as passive passivators, unable to actively regulate the perovskite crystallization process to obtain better film morphologies (e.g., large grains, low pinhole density, vertical orientation), leaving many defects at grain boundaries. 3. Limited stability improvement. The mechanisms by which traditional additives suppress ion migration and enhance phase stability are unclear or their effects are not long-lasting, making it difficult to fundamentally improve the stability of devices under long-term operating conditions. 4. Potential side effects. Some small-molecule additives (e.g., certain organic ammonium salts) may volatilize or decompose during processing or use, and their organic cations may invade the perovskite lattice, introducing new instability factors.

[0005] Therefore, developing a perovskite solar cell that can comprehensively passivate multiple defects, actively optimize thin film quality, and fundamentally improve stability, as well as its fabrication method, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the present invention provides a perovskite solar cell based on the additive 4,6-dichloro-1,3,5-triazine-2-amine and its preparation method. A multifunctional additive with a unique molecular structure—4,6-dichloro-1,3,5-triazine-2-amine—is introduced into the perovskite precursor solution to prepare a high-performance, high-stability perovskite solar cell. Through the synergistic effect of its three functional groups—triazine ring, amino group, and chlorine atom—the 4,6-dichloro-1,3,5-triazine-2-amine additive simultaneously achieves comprehensive defect passivation and optimization of the crystallization process at the single-molecule level, which is impossible to achieve with existing single-functional additives.

[0007] To achieve the above objectives, the present invention mainly adopts the following technical solutions:

[0008] First, a perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive is provided, comprising a perovskite light-absorbing layer. The perovskite light-absorbing layer is obtained by dissolving lead iodide, lead bromide, formamidinium hydroiodate, methylammonium bromide, methylammonium chloride, cesium iodide, and 4,6-dichloro-1,3,5-triazine-2-amine in an organic solvent, heating and stirring to obtain a perovskite precursor solution, and then spin-coating the perovskite precursor solution onto a nickel oxide hole transport layer, followed by annealing.

[0009] Its beneficial effects are as follows: Adding 4,6-dichloro-1,3,5-triazine-2-amine to the perovskite precursor solution ensures uniform dispersion and pre-interaction with the precursor components. 4,6-dichloro-1,3,5-triazine-2-amine plays a crucial role in spin-coating and subsequent annealing and crystallization processes, specifically as follows: (1) Lewis base coordination: The nitrogen atom (electron-rich) on the triazine ring in the molecule acts as a strong Lewis base and interacts with the uncoordinated Pb. 2+ Ions (from lead vacancies or dangling bonds in the lattice) undergo strong coordination, effectively filling lead vacancies and suppressing the formation of deep-level defects.

[0010] (2) Lewis acid interactions and hydrogen bond formation: Chlorine atoms (electron-deficient) on the molecule can serve as Lewis acid sites, interacting with organic cations in perovskite (such as FA). + It interacts with other electron-deficient sites. Simultaneously, the terminal amino group (-NH2) can interact with halide ions (I-) in the perovskite. - They form NH…I hydrogen bonds, thus fixing halide ions.

[0011] (3) Crystallization kinetics regulation: The above-mentioned multiple interactions can regulate the nucleation and growth rate of perovskite. The rigid triazine ring structure of the additive may delay the crystallization process through steric hindrance, promote the growth of larger grains, and may induce more favorable crystal orientation, thereby obtaining dense, flat perovskite polycrystalline thin films with low defect density.

[0012] (4) Continuous stabilizing effect in the final device: After crystallization, some additive molecules may be confined to grain boundaries or thin film surfaces. Their rigid structure acts like a "nanolock" or "cross-linking point", anchoring the lattice through continuous coordination and hydrogen bonding, increasing the activation energy of ion migration, thereby physically inhibiting the migration of halide ions and lead ions under light and thermal stress, and significantly enhancing the intrinsic stability of the device.

[0013] Preferably, the mass ratio of lead iodide, lead bromide, formamidinium hydroiodate, methylammonium bromide, methylammonium chloride, cesium iodide, and 4,6-dichloro-1,3,5-triazine-2-amine is 676:27.5:232:8:15.2:19.5:0.5~2.

[0014] Preferably, the organic solvent is a mixture of dimethylformamide and dimethyl sulfoxide, wherein the ratio of dimethylformamide to dimethyl sulfoxide is 4:1, and the mass ratio of lead iodide to the volume ratio of the organic solvent is 676 mg: 1000 mL.

[0015] Preferably, the heating and stirring temperature is 60°C and the time is 1 hour.

[0016] Preferably, the spin coating conditions are: spin coating at a low speed of 1000 rpm for 10 s, followed by spin coating at a high speed of 5000 rpm for 30 s, with 150 μL of chlorobenzene added 10 s before the end of the program. The annealing was performed at 100°C for 30 minutes.

[0017] Preferably, the perovskite solar cell has an inverted structure, consisting of, from bottom to top: an ITO conductive substrate, a nickel oxide hole transport layer, a perovskite light-absorbing layer, a PCBM electron transport layer, a BCP interface modification layer, and an Ag metal electrode.

[0018] In addition, the present invention also provides a method for preparing a perovskite solar cell based on the above-described 4,6-dichloro-1,3,5-triazine-2-amine additive, specifically comprising the following steps: S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate.

[0019] S2, spin-coat a nickel oxide nanoparticle solution onto the surface of an ITO conductive substrate, anneal, and obtain a nickel oxide hole transport layer.

[0020] S3. Prepare a perovskite precursor solution, spin-coat the perovskite precursor solution onto the surface of the nickel oxide hole transport layer, and anneal to obtain a perovskite light-absorbing layer.

[0021] S4. Prepare a PCBM solution and spin-coat the PCBM solution onto the surface of the perovskite light-absorbing layer to obtain a PCBM electron transport layer.

[0022] S5. Prepare a BCP solution and spin-coat the BCP solution onto the surface of the PCBM electron transport layer to obtain a BCP interface modification layer.

[0023] S6, evaporate Ag electrode to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

[0024] The nickel oxide nanoparticle solution in step S2 is prepared using deionized water at a concentration of 20 mg / mL. The spin-coating conditions are: spin-coating at 4000 rpm for 30 s, annealing at 100℃ for 10 min.

[0025] The PCBM solution in step S4 uses chlorobenzene as the solvent, has a concentration of 23 mg / mL, and is spin-coated at a speed of 2500 rmp / min for 40 s.

[0026] The BCP solution in step S5 uses isopropanol as the solvent, with a concentration of 0.5 mg / mL, and spin-coating conditions are 5000 rmp / min for 30 s.

[0027] In summary, compared with the prior art, this application provides a perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive and its preparation method, the advantages of which are: 1) Comprehensive passivation of multiple defects: It solves the problem that traditional additives can only passivate a single type of defect (such as only passivating lead defects or only passivating halogen defects), and realizes the simultaneous and synergistic passivation of lead-related defects and halogen-related defects, which greatly reduces the overall defect density of the film.

[0028] 2) Active optimization of film quality: This invention solves the problem of additives being passively passivated and unable to guide the growth of high-quality crystals. The additives of this invention can actively regulate crystallization kinetics, promoting the formation of perovskite films with larger, denser grains and better orientation.

[0029] 3) Fundamentally improved stability: It solves the problem of performance degradation caused by ion migration under operating conditions. Through the molecular "anchoring" effect, ion migration is significantly suppressed, thereby improving the light and thermal stability of the device.

[0030] 4) "One agent, multiple effects": One molecule integrates the functions of Lewis base, Lewis acid and hydrogen bond donor / acceptor. It has a delicate structure, high efficiency and avoids the compatibility problems that may be caused by using multiple additives.

[0031] 5) Significant performance improvement: Perovskite solar cells fabricated based on this additive show significantly improved open-circuit voltage (Voc) and fill factor (FF), resulting in higher photoelectric conversion efficiency. Simultaneously, the long-term stability of the device (including maximum power point tracking stability and 85℃ thermal stability) is improved several times over.

[0032] 6) Good process compatibility: The additives are easy to synthesize and purify, and have good solubility in conventional precursor solvents. Their introduction does not change the existing mainstream perovskite device fabrication process, and they are easy to integrate and promote. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1 SEM images of the perovskite films in Comparative Example 1 and Examples 1-3.

[0035] Figure 2 The XRD patterns are of the perovskite films in Comparative Example 1 and Examples 1-3.

[0036] Figure 3 The steady-state fluorescence spectrum and transient fluorescence lifetime of the perovskite films in Comparative Example 1 and Example 2 are shown.

[0037] Figure 4 The images show the SCLC diagrams of the perovskite devices in Comparative Example 1 and Example 2.

[0038] Figure 5 The images show the in-situ fluorescence spectra of the perovskite films in Comparative Example 1 and Example 2.

[0039] Figure 6 The JV curves are for the devices in Comparative Examples 1-2 and Example 2.

[0040] Figure 7 The stability graphs are for the perovskite thin devices in Comparative Example 1 and Example 2. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1 S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate. S2, a nickel oxide nanoparticle solution was spin-coated onto the surface of an ITO conductive substrate. The solvent was deionized water with a concentration of 20 mg / mL. The spin-coating conditions were: spin-coating at 4000 rmp / min for 30 s, followed by annealing at 100℃ for 10 min to obtain a nickel oxide hole transport layer with a thickness of approximately 20 nm. S3. Weigh out 676 mg of lead iodide, 27.5 mg of lead bromide, 232 mg of formamidinium hydroiodate, 8 mg of methylammonium bromide, 15.2 mg of methylammonium chloride, 19.5 mg of cesium iodide, and 0.5 mg of 4,6-dichloro-1,3,5-triazine-2-amine, and dissolve them in 800 mL of a mixed organic solvent of dimethylformamide and 200 mL of dimethyl sulfoxide (volume ratio 4:1). Heat and stir on a 60°C heating plate for 1 hour to prepare a perovskite precursor solution. Spin-coat the perovskite precursor solution onto the surface of the nickel oxide hole transport layer. The spin-coating conditions are: low speed 1000 rpm spin-coating for 10 s, then high speed 5000 rpm spin-coating for 30 s. Add 150 μL of chlorobenzene 10 s before the end of the program. Anneal at 100°C for 30 min to obtain the perovskite light-absorbing layer. S4. Prepare a PCBM solution with chlorobenzene as the solvent and a concentration of 23 mg / mL. Spin-coat the PCBM solution onto the surface of the perovskite light-absorbing layer at a spin speed of 2500 rmp / min for 40 s without annealing to obtain the PCBM electron transport layer. S5. Prepare a BCP solution with isopropanol as the solvent and a concentration of 0.5 mg / mL. Spin-coat the BCP solution onto the surface of the PCBM electron transport layer at a spin speed of 5000 rmp / min for 30 s without annealing to obtain a BCP interface modification layer. S6, evaporate Ag electrode to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

[0043] Example 2 S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate. S2, a nickel oxide nanoparticle solution was spin-coated onto the surface of an ITO conductive substrate. The solvent was deionized water with a concentration of 20 mg / mL. The spin-coating conditions were: spin-coating at 4000 rmp / min for 30 s, followed by annealing at 100℃ for 10 min to obtain a nickel oxide hole transport layer with a thickness of approximately 20 nm. S3. Weigh out 676 mg of lead iodide, 27.5 mg of lead bromide, 232 mg of formamidinium hydroiodate, 8 mg of methylammonium bromide, 15.2 mg of methylammonium chloride, 19.5 mg of cesium iodide, and 1 mg of 4,6-dichloro-1,3,5-triazine-2-amine. Dissolve these substances in 800 mL of a mixed organic solvent of dimethylformamide and 200 mL of dimethyl sulfoxide (volume ratio 4:1). Heat and stir on a 60°C heating plate for 1 hour to prepare a perovskite precursor solution. Spin-coat the perovskite precursor solution onto the surface of the nickel oxide hole transport layer. The spin-coating conditions are: low speed 1000 rpm spin-coating for 10 s, then high speed 5000 rpm spin-coating for 30 s. Add 150 μL of chlorobenzene 10 s before the end of the program. Anneal at 100°C for 30 min to obtain the perovskite light-absorbing layer. S4. Prepare a PCBM solution with chlorobenzene as the solvent and a concentration of 23 mg / mL. Spin-coat the PCBM solution onto the surface of the perovskite light-absorbing layer at a spin speed of 2500 rmp / min for 40 s without annealing to obtain the PCBM electron transport layer. S5. Prepare a BCP solution with isopropanol as the solvent and a concentration of 0.5 mg / mL. Spin-coat the BCP solution onto the surface of the PCBM electron transport layer at a spin speed of 5000 rmp / min for 30 s without annealing to obtain a BCP interface modification layer. S6, evaporate Ag electrode to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

[0044] Example 3 S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate. S2, a nickel oxide nanoparticle solution was spin-coated onto the surface of an ITO conductive substrate. The solvent was deionized water with a concentration of 20 mg / mL. The spin-coating conditions were: spin-coating at 4000 rmp / min for 30 s, followed by annealing at 100℃ for 10 min to obtain a nickel oxide hole transport layer with a thickness of approximately 20 nm. S3, weigh out 676 mg of lead iodide, 27.5 mg of lead bromide, 232 mg of formamidinium hydroiodate, 8 mg of methylammonium bromide, 15.2 mg of methylammonium chloride, 19.5 mg of cesium iodide, and 2 mg of 4,6-dichloro-1,3,5-triazine-2-amine, and dissolve them in 800 mL of a mixed organic solvent of dimethylformamide and 200 mL of dimethyl sulfoxide (volume ratio 4:1). Heat and stir on a 60°C heating plate for 1 hour to prepare a perovskite precursor solution. Spin-coat the perovskite precursor solution onto the surface of the nickel oxide hole transport layer. The spin-coating conditions are: low speed 1000 rpm spin-coating for 10 s, then high speed 5000 rpm spin-coating for 30 s. Add 150 μL of chlorobenzene 10 s before the end of the program. Anneal at 100°C for 30 min to obtain the perovskite light-absorbing layer. S4. Prepare a PCBM solution with chlorobenzene as the solvent and a concentration of 23 mg / mL. Spin-coat the PCBM solution onto the surface of the perovskite light-absorbing layer at a spin speed of 2500 rmp / min for 40 s without annealing to obtain the PCBM electron transport layer. S5. Prepare a BCP solution with isopropanol as the solvent and a concentration of 0.5 mg / mL. Spin-coat the BCP solution onto the surface of the PCBM electron transport layer at a spin speed of 5000 rmp / min for 30 s without annealing to obtain a BCP interface modification layer. S6, evaporate Ag electrode to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

[0045] Comparative Example 1 S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate. S2, a nickel oxide nanoparticle solution was spin-coated onto the surface of an ITO conductive substrate. The solvent was deionized water with a concentration of 20 mg / mL. The spin-coating conditions were: spin-coating at 4000 rmp / min for 30 s, followed by annealing at 100℃ for 10 min to obtain a nickel oxide hole transport layer with a thickness of approximately 20 nm. S3. Weigh out 676 mg of lead iodide, 27.5 mg of lead bromide, 232 mg of formamidinium hydroiodate, 8 mg of methylammonium bromide, 15.2 mg of methylammonium chloride, and 19.5 mg of cesium iodide. Dissolve these substances in 800 mL of a mixed organic solvent of dimethylformamide and 200 mL of dimethyl sulfoxide (volume ratio 4:1). Heat and stir on a 60°C heating plate for 1 hour to prepare a perovskite precursor solution. Spin-coat the perovskite precursor solution onto the surface of the nickel oxide hole transport layer. The spin-coating conditions are: low speed 1000 rpm spin-coating for 10 s, then high speed 5000 rpm spin-coating for 30 s. Add 150 μL of chlorobenzene 10 s before the end of the program. Anneal at 100°C for 30 min to obtain the perovskite light-absorbing layer. S4. Prepare a PCBM solution with chlorobenzene as the solvent and a concentration of 23 mg / mL. Spin-coat the PCBM solution onto the surface of the perovskite light-absorbing layer at a spin speed of 2500 rmp / min for 40 s without annealing to obtain the PCBM electron transport layer. S5. Prepare a BCP solution with isopropanol as the solvent and a concentration of 0.5 mg / mL. Spin-coat the BCP solution onto the surface of the PCBM electron transport layer at a spin speed of 5000 rmp / min for 30 s without annealing to obtain a BCP interface modification layer. S6, evaporate Ag electrode to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

[0046] Comparative Example 2 S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate. S2, a nickel oxide nanoparticle solution was spin-coated onto the surface of an ITO conductive substrate. The solvent was deionized water with a concentration of 20 mg / mL. The spin-coating conditions were: spin-coating at 4000 rmp / min for 30 s, followed by annealing at 100℃ for 10 min to obtain a nickel oxide hole transport layer with a thickness of approximately 20 nm. S3. Weigh out 676 mg of lead iodide, 27.5 mg of lead bromide, 232 mg of formamidinium hydroiodate, 8 mg of methylammonium bromide, 15.2 mg of methylammonium chloride, 19.5 mg of cesium iodide, and 1 mg of 1,3,5-triazine-2-amine. Dissolve these substances in 800 mL of a mixed organic solvent of dimethylformamide and 200 mL of dimethyl sulfoxide (volume ratio 4:1). Heat and stir on a 60°C heating plate for 1 hour to prepare a perovskite precursor solution. Spin-coat the perovskite precursor solution onto the surface of the nickel oxide hole transport layer. The spin-coating conditions are: low speed 1000 rpm spin-coating for 10 s, then high speed 5000 rpm spin-coating for 30 s. Add 150 μL of chlorobenzene 10 s before the end of the program. Anneal at 100°C for 30 min to obtain the perovskite light-absorbing layer. S4. Prepare a PCBM solution with chlorobenzene as the solvent and a concentration of 23 mg / mL. Spin-coat the PCBM solution onto the surface of the perovskite light-absorbing layer at a spin speed of 2500 rmp / min for 40 s without annealing to obtain the PCBM electron transport layer. S5. Prepare a BCP solution with isopropanol as the solvent and a concentration of 0.5 mg / mL. Spin-coat the BCP solution onto the surface of the PCBM electron transport layer at a spin speed of 5000 rmp / min for 30 s without annealing to obtain a BCP interface modification layer. S6, evaporate Ag electrode to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

[0047] Characterization Test Analysis Figure 1 The images are scanning electron microscope images of the perovskite films in Comparative Example 1 and Examples 1-3. It can be seen from the images that the perovskite particles in Comparative Example 1 are uniformly and tightly arranged, and there are obvious voids on the surface of the film. In Example 2, the perovskite grain size is slightly increased, and there are no obvious voids.

[0048] Figure 2 The XRD patterns of the perovskite films in Comparative Example 1 and Examples 1-3 are shown. The diffraction peaks are significantly enhanced after modification with 4,6-dichloro-1,3,5-triazine-2-amine, indicating a substantial improvement in the crystallinity of the perovskite film, thus enhancing its quality and reducing defect states.

[0049] Figure 3 The images show the steady-state fluorescence spectra and transient fluorescence lifetimes of the perovskite films in Comparative Example 1 and Example 2. The perovskite films modified with 4,6-dichloro-1,3,5-triazine-2-amine exhibited improved fluorescence intensity and lifetime, indicating a significant reduction in the defect state density and the acquisition of high-quality perovskite films.

[0050] Figure 4 The images show the SCLC plots of the perovskite devices in Example 1 and Example 2. Example 2 achieved a lower VTFL, further demonstrating the reduction in defects.

[0051] Figure 5 In-situ fluorescence spectra of the perovskite films in Comparative Example 1 and Example 2. The perovskite film in Example 2 showed significant changes in fluorescence intensity and peak position during crystallization, indicating that 4,6-dichloro-1,3,5-triazine-2-amine can effectively regulate perovskite crystallization kinetics, induce ordered perovskite growth, and prepare high-quality perovskite films.

[0052] Figure 6 To compare the current density-voltage performance curves of the device and the implementation device, the graph shows that the open-circuit voltage of the perovskite solar cell in Comparative Example 1 is 1.144 V, and the short-circuit current density is 25.64 mA cm⁻¹. -2 The fill factor was 79.85%, the photoelectric conversion efficiency was 23.425%, and the open-circuit voltage of the perovskite solar cell in Example 2 was 1.183 V, with a short-circuit current density of 25.68 mA cm⁻¹. -2 The fill factor was 84.345%, and the photoelectric conversion efficiency was higher than 25.642%. In Comparative Example 2, the additive was 1,3,5-triazine-2-amine; the open-circuit voltage of the device was 1.172 V, and the short-circuit current density was 25.42 mA cm⁻¹. -2 The fill factor was 81.87%, and the photoelectric conversion efficiency was 24.39%. Example 2 achieved the highest photoelectric conversion efficiency. The improved device performance can be attributed to the ability of 4,6-dichloro-1,3,5-triazine-2-amine to regulate perovskite growth, reduce defects, improve the quality of the perovskite film and radiative recombination efficiency, thereby improving the photoelectric conversion efficiency of the device.

[0053] Figure 7 The graphs show the stability of the perovskite thin devices in Comparative Example 1 and Example 2. The stability of the perovskite device modified with 4,6-dichloro-1,3,5-triazine-2-amine steadily improved. Under nitrogen atmosphere, Example 2 maintained a conversion efficiency of over 90% after 2000 hours, while the conversion efficiency of Comparative Example 1 decreased rapidly. Similarly, in air atmosphere, Example 2 maintained a conversion efficiency of around 80% after 1200 hours, significantly higher than the comparative device.

[0054] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A perovskite solar cell based on a 4,6-dichloro-1,3,5-triazine-2-amine additive, characterized in that, The perovskite light-absorbing layer is obtained by dissolving lead iodide, lead bromide, formamidinium hydroiodate, methylammonium bromide, methylammonium chloride, cesium iodide, and 4,6-dichloro-1,3,5-triazine-2-amine in an organic solvent, heating and stirring to obtain a perovskite precursor solution, and then spin-coating the perovskite precursor solution onto a nickel oxide hole transport layer and annealing it.

2. The perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive according to claim 1, characterized in that, The mass ratio of lead iodide, lead bromide, formamidinium hydroiodate, methylammonium bromide, methylammonium chloride, cesium iodide, and 4,6-dichloro-1,3,5-triazine-2-amine is 676:27.5:232:8:15.2:19.5:0.5~2.

3. The perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive according to claim 1, characterized in that, The organic solvent is a mixture of dimethylformamide and dimethyl sulfoxide, wherein the ratio of dimethylformamide to dimethyl sulfoxide is 4:1, and the mass ratio of lead iodide to organic solvent is 676 mg: 1000 mL.

4. The perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive according to claim 1, characterized in that, The heating and stirring process is carried out at a temperature of 60°C for 1 hour.

5. The perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive according to claim 1, characterized in that, The spin coating conditions were: low speed 1000 rpm spin coating for 10 s, then high speed 5000 rpm spin coating for 30 s, and 150 μL of chlorobenzene was added 10 s before the end of the program. The annealing was performed at 100°C for 30 minutes.

6. The perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive according to claim 1, characterized in that, The perovskite solar cell has an inverted structure, consisting of, from bottom to top: an ITO conductive substrate, a nickel oxide hole transport layer, a perovskite light-absorbing layer, a PCBM electron transport layer, a BCP interface modification layer, and an Ag metal electrode.

7. A method for preparing a perovskite solar cell based on a 4,6-dichloro-1,3,5-triazine-2-amine additive as described in claim 6, characterized in that, Specifically, the steps include the following: S1. After cleaning and drying the ITO transparent conductive glass substrate, treat it with ultraviolet light and ozone to obtain the ITO conductive substrate. S2, spin-coat a nickel oxide nanoparticle solution onto the surface of an ITO conductive substrate, anneal, and obtain a nickel oxide hole transport layer; S3, prepare a perovskite precursor solution, spin-coat the perovskite precursor solution on the surface of the nickel oxide hole transport layer, anneal, and obtain a perovskite light-absorbing layer. S4. Prepare PCBM solution and spin-coat PCBM solution onto the surface of perovskite light-absorbing layer to obtain PCBM electron transport layer. S5. Prepare a BCP solution and spin-coat the BCP solution onto the surface of the PCBM electron transport layer to obtain a BCP interface modification layer. S6, deposit Ag electrode by vapor deposition to obtain the perovskite solar cell based on 4,6-dichloro-1,3,5-triazine-2-amine additive.

8. The method according to claim 7, characterized in that, The nickel oxide nanoparticle solution in step S2 is prepared using deionized water at a concentration of 20 mg / mL. The spin-coating conditions are: spin-coating at 4000 rpm for 30 s, annealing at 100℃ for 10 min.

9. The method according to claim 7, characterized in that, The PCBM solution in step S4 uses chlorobenzene as the solvent, has a concentration of 23 mg / mL, and is spin-coated at a speed of 2500 rmp / min for 40 s.

10. The method according to claim 7, characterized in that, The BCP solution in step S5 uses isopropanol as the solvent, with a concentration of 0.5 mg / mL, and spin-coating conditions are 5000 rmp / min for 30 s.

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