Perovskite solar cell with liquid crystal modification layer and preparation method

Abstract

The invention discloses a perovskite solar cell with a liquid crystal modification layer and a preparation method, and belongs to the technical field of perovskite solar cells. The liquid crystal modification layer is 2 '-fluoro-4' '-propyl-[1, 1'; the preparation method comprises the following steps: introducing 4, 4 ', 1'-terphenyl]-4-formonitrile (3PGPCN) into a SnO2 / perovskite interface to construct an interface regulation and control system with a triple synergistic effect, and forming an ordered molecular layer under the pi-pi accumulation action of a biphenyl structure to induce oriented growth of perovskite; c is equivalent to N which is coordinated with Sn sites on the surface of SnO2 and passivates Pb < 2 + > defects in perovskite, and fluorine atoms can passivate oxygen vacancies (VO) on the surface of SnO2 and inhibit migration of formamidine cations (FA < + >) in perovskite. In addition, the molecular dipole moment can regulate and control the energy band structure of the interface. The perovskite solar cell optimized by the 3PGPCN obtains the photoelectric conversion efficiency of 25.46%, and has excellent working stability.

Description

A perovskite solar cell with a liquid crystal modified layer and its preparation method Technical Field

[0001] This invention relates to the field of perovskite material and device fabrication technology, specifically to a perovskite solar cell with a liquid crystal modified layer and its fabrication method. Background Technology

[0002] With the increasing severity of global climate change and resource scarcity, the high carbon emissions and non-renewable nature of traditional fossil fuels are no longer sufficient to meet the sustainable development needs of modern society. The large-scale use of fossil fuels has not only exacerbated greenhouse gas emissions but also led to serious environmental pollution and energy security problems. For example, fossil fuels such as coal, oil, and natural gas release large amounts of carbon dioxide, sulfur dioxide, and nitrogen oxides during combustion. These pollutants not only cause severe damage to the ecological environment but also have long-term negative impacts on human health. Furthermore, the non-renewable nature of fossil fuels leads to frequent price fluctuations, further threatening the stability of global energy supply. Against this backdrop, the rapid development of new energy technologies has become a key path for global energy transformation. Clean energy, represented by wind and solar power, is gradually replacing traditional fossil fuels and becoming an important component of the future energy structure due to its clean and renewable characteristics.

[0003] Among numerous photovoltaic technologies, perovskite solar cells (PSCs) are widely recognized as the most promising next-generation thin-film photovoltaic technology due to their outstanding advantages such as high photoelectric conversion efficiency, low material cost, and solution-processability. After more than a decade of rapid development, the certified efficiency of single-junction perovskite solar cells has jumped from the initial 3.8% to 27.0%, approaching the theoretical limit of monocrystalline silicon solar cells and demonstrating enormous potential to compete with commercial silicon-based photovoltaic technologies.

[0004] The core performance of PSCs (Power Sinks) relies heavily on efficient carrier transport and low-defect interfaces in each functional layer, with the interface quality between the electron transport layer (ETL) and the perovskite light-absorbing layer being particularly critical. SnO2, a wide-bandgap n-type semiconductor, is widely used as an ETL material due to its high electron mobility, excellent optical transmittance, and good energy level matching with the perovskite layer. However, defects at the SnO2 / perovskite buried interface severely restrict further improvements in device performance. These interface defects mainly originate from two sources: firstly, the intrinsic oxygen vacancies and dangling bonds on the SnO2 surface, which easily form deep-level trap states; and secondly, uncoordinated Pb at the perovskite buried interface. 2+ These defects can lead to nonradiative recombination at the interface, reduce carrier extraction efficiency, and exacerbate hysteresis and open-circuit voltage loss, significantly reducing device performance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a perovskite solar cell with a liquid crystal modified layer and its preparation method, so as to solve the problem of low photoelectric conversion efficiency of perovskite solar cells caused by a large number of interface defects between the electron transport layer and the perovskite light-absorbing layer.

[0006] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing a perovskite solar cell with a liquid crystal modified layer, comprising the following steps: S1, spin-coating a SnO2 colloidal nanoparticle solution onto a glass substrate, and obtaining an electron transport layer after annealing; S2, dissolving 3PGPCN solid powder in chlorobenzene, stirring to obtain a modified layer solution, spin-coating the modified layer solution onto the electron transport layer, and obtaining a liquid crystal modified layer after annealing; wherein the 3PGPCN solid powder is 2'-fluoro-4”-propyl-[1,1';4',1”-terphenyl]-4-carboxynitrile, with the structural formula: S3, FA 0.9 Cs 0.1 A PbI3 perovskite precursor solution was spin-coated onto a liquid crystal modification layer, and then annealed to obtain FA. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer; S4, in FA 0.9 Cs 0.1 Spiro fabrication on PbI3 perovskite light-absorbing layer OMeTAD hole transport layer; S5, in Spiro Metal electrodes were fabricated on the OMeTAD hole transport layer to obtain a perovskite solar cell with a liquid crystal modification layer.

[0007] A further improvement of the present invention is that, preferably, in S1, the solute of the SnO2 colloidal nanoparticle solution is SnO2 colloidal nanoparticles, and the solvent is water; in S1, the annealing temperature is 100 ℃, and the annealing time is 30-40 min.

[0008] Preferably, in S2, the concentration of the modified layer solution is 0.25-1.0 mg / mL.

[0009] Preferably, in S2, the spin coating speed of the modification layer solution is 2000-4000 rpm, and the spin coating time is 30 s.

[0010] Preferably, in S2, the annealing temperature is 100 ℃ and the annealing time is 10-15 min.

[0011] Preferably, in S3, the concentration of the perovskite precursor solution is 1.0 M.

[0012] Preferably, in S3, the perovskite precursor solution is spin-coated in two stages: the first stage has a rotation speed of 1000-2000 rpm and a time of 10 s; the second stage has a rotation speed of 4000-5000 rpm and a time of 30 s.

[0013] Preferably, in S4, the Spiro The rotation speed of the OMeTAD hole transport layer is 5000 rpm, and the spin coating time is 30 s.

[0014] Preferably, in S1, the glass substrate is FTO glass, and in S5, the metal electrode is gold.

[0015] A perovskite solar cell with a liquid crystal modified layer includes, from bottom to top, a stripped substrate, a SnO2 electron transport layer, a 3PGPCN liquid crystal modified layer, and a FA layer. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer, Spiro OMeTAD hole transport layer and metal electrode; the 3PGPCN in the 3PGPCN liquid crystal modification layer is 2'-fluoro-4”-propyl-[1,1';4',1”-terphenyl]-4-carboxynitrile, with the following structural formula: .

[0016] Compared with existing technologies, the present invention has the following advantages: The present invention discloses a method for preparing a perovskite solar cell with a liquid crystal modified layer. This method modifies the surface of the SnO2 electron transport layer of the perovskite solar cell with a layer of 2'-fluoro-4”-propyl-[1,1';4',1”-terphenyl]-4-carboxynitrile (3PGPCN) at different concentrations (0.25-1.0 mg / mL) using chlorobenzene as the solvent, thereby simultaneously improving the efficiency and stability of the perovskite solar cell. This material is a multifunctional liquid crystal molecule that can interact not only with the SnO2 electron transport layer but also with the perovskite. The interaction between SnO2 and 3PGPCN allows the cyano groups in 3PGPCN to form coordination bonds with Sn ions on the SnO2 surface, effectively passivating Sn-based defects. The F ions in 3PGPCN form hydrogen bonds with hydroxyl groups on the SnO2 surface, suppressing oxygen vacancies. In this structure, the presence of cyano and F atoms, besides interacting with SnO2 and perovskite, also enhances the dipole moment of the liquid crystal material itself, thereby modulating the band structure of the interface and promoting the directional separation and transport of charge carriers. The interaction between perovskite and 3PGPCN also involves the cyano groups and F ions in 3PGPCN reacting with uncoordinated Pb atoms in the perovskite. 2+ Coordination occurs, reducing Pb 2+ Dangling bond defects. Simultaneously, F ions interact with FA... + -NH2 in the middle forms N─H F hydrogen bonds effectively inhibit FA + The migration of cations at grain boundaries stabilizes the perovskite crystal structure. Furthermore, 3PGPCN molecules exert their dynamic self-assembly effect, forming an orientation template through the π-π stacking of rigid conjugated biphenyl structures. This results in a dense and ordered molecular layer on the SnO2 surface, inducing the crystallization and growth of the perovskite film, regulating the crystallization process, promoting ordered grain growth, and thus reducing the defect state density at grain boundaries. This interfacial bridging effect passivates the lower interface (SnO2 surface) and the upper interface (perovskite bottom). This not only optimizes the crystallization orientation of the perovskite film but also promotes the directional separation and transport of charge carriers by regulating the interfacial band structure through molecular dipole moments. The perovskite solar cell optimized with 3PGPCN achieved a photoelectric conversion efficiency of 25.46% and excellent stability. This invention achieves dual optimization of charge carrier transport dynamics and non-radiative recombination losses by synergistically regulating the defect state density of the electron transport layer and the energy level arrangement of the perovskite layer through an interface modification strategy. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the perovskite solar cell described in Embodiment 1 of the present invention; in the figure: from bottom to top, the layers are: FTO substrate, SnO2 electron transport layer, 3PGPCN interface modification layer, and FA. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer, Spiro-OMeTAD hole transport layer, and metal electrode.

[0018] Figure 2 is a comparison of SEM scans of the perovskite thin film before and after modification with 3PGPCN on the surface of the SnO2 electron transport layer as described in Example 1 of the present invention; wherein, (a) is the unmodified film and (b) is the film modified with 3PGPCN.

[0019] Figure 3 shows the XPS spectrum of the interaction between 3PGPCN and SnO2 described in Embodiment 1 of the present invention; wherein, (a) is the Sn 3d spectrum and (b) is the O 1s spectrum.

[0020] Figure 4 is the XPS spectrum of the interaction between 3PGPCN and PbI2 described in Example 1 of the present invention; Figure 5 is the FTIR spectrum of the interaction between 3PGPCN and PbI2 described in Example 1 of the present invention; Figure 6 is the electron mobility and conductivity spectrum of the unmodified and modified SnO2 films described in Example 1 of the present invention; wherein, (a) is the electron mobility and (b) is the conductivity.

[0021] Figure 7 shows the PL spectra of the perovskite films with and without modification of the SnO2 electron transport layer surface after modification with 3PGPCN as described in Example 1 of the present invention; Figure 8 shows the TRPL spectra of the perovskite films with and without modification of the SnO2 electron transport layer surface after modification with 3PGPCN as described in Example 1 of the present invention; Figure 9 shows the UPS comparison of the SnO2 films with and without modification of the SnO2 electron transport layer surface after modification with 3PGPCN as described in Example 1 of the present invention; Figure 10 shows the JV curves of the perovskite solar cells with and without modification of the SnO2 electron transport layer surface after modification with 3PGPCN as described in Example 1 of the present invention; Figure 11 shows the stability of the perovskite solar cells with and without modification of the SnO2 electron transport layer surface after modification with 3PGPCN as described in Example 1 of the present invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are generally explained and defined below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0023] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0025] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0026] This invention discloses a liquid crystal material. The first aspect of this invention discloses a method for preparing a perovskite solar cell with a liquid crystal modified layer, comprising the following steps: Step 1, cleaning the FTO glass substrate; cutting the FTO glass to a size of 2.5×2.5 cm, mixing glass cleaner and ultrapure water at a volume ratio of 1:100, placing the FTO glass in an ultrasonic cleaner and sonicating for 30 min, removing it and rinsing the FTO glass and the inner wall of the beaker with ultrapure water, repeating the sonication 3 times, immersing the cleaned FTO glass in clean anhydrous ethanol for later use, and drying it with an air compressor before use.

[0027] Step 2: Prepare the SnO2 electron transport layer precursor solution and the chlorobenzene solution of 3PGPCN. The method for preparing the SnO2 electron transport layer precursor solution is as follows: Dissolve an appropriate amount of SnO2 colloidal nanoparticles (V / V = 1:6) in deionized water and stir at room temperature for 6-8 hours to ensure homogeneous mixing. The 3PGPCN solution is prepared by dissolving 0.25-1.0 mg of 3PGPCN solid in 1 mL of chlorobenzene and stirring at room temperature for 1-2 hours to obtain a 0.25-1.0 mg / mL 3PGPCN chlorobenzene solution. Before use, the solution should be filtered through a 0.45 μm filter.

[0028] The 3PGPCN solid is a liquid crystal material 2'-fluoro-4”-propyl-[1,1';4',1”-terphenyl]-4-carboxynitrile, with the following structural formula: .

[0029] This liquid crystal material simultaneously possesses a cyano group, an F atom, a terphenyl conjugated structure, and a suitable liquid crystal phase range. These properties can not only effectively passivate the interface defects between SnO2 and the perovskite light-absorbing layer, but also induce the directional growth of perovskite and regulate the crystallization kinetics of perovskite, thereby reducing the defect state density at the grain boundaries.

[0030] Step 3: Preparation of the SnO2 electron transport layer; After treating the FTO glass cleaned in Step 1 with ultraviolet ozone for 10-15 min, spin-coat the SnO2 colloidal nanoparticle solution prepared in Step 2 onto the FTO substrate surface at a spin-coating speed of 2500-4000 rpm for 40 s. Then, annealing is performed at 100 ℃ for 30-40 min to obtain the SnO2 electron transport layer. Before spin-coating the 3PGPCN chlorobenzene solution, the FTO / SnO2 substrate is treated with ultraviolet ozone for 10-15 min.

[0031] Step 4: Prepare the 3PGPCN modification layer; spin-coat the 3PGPCN chlorobenzene solution prepared in Step 2 onto the surface of the SnO2 electron transport layer obtained in Step 3. The spin-coating speed is 2000-4000 rpm, and the spin-coating time is 30 s. Then, annealing is performed at 100 ℃ for 10-15 min to obtain the 3PGPCN interface modification layer. Before spin-coating the perovskite precursor solution, the FTO / SnO2 / 3PGPCN substrate is treated with ultraviolet ozone for 10-15 min.

[0032] Step 5, prepare FA 0.9 Cs 0.1 PbI3 perovskite precursor solution; 1.0 M FA solution was prepared by dissolving formamidinium hydroiodate (FAI), cesium iodide (CsI), and lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5). 0.9 Cs 0.1 PbI3 perovskite precursor solution: Stir the perovskite precursor solution for 6-12 h, then filter it using a 0.45 μm filter cartridge for later use.

[0033] Step 6, Prepare FA 0.9 Cs 0.1 A PbI3 perovskite light-absorbing layer was then applied. The perovskite precursor solution prepared in step 5 was spin-coated onto the surface of an FTO / SnO2 / 3PGPCN substrate. The spin-coating process was completed in two stages: the first stage was at a spin speed of 1000-2000 rpm for 10 s; the second stage was at a spin speed of 4000-5000 rpm for 30 s. An annealing process was then performed at a temperature of 120°C. o C, annealing time is 30-40 min. After annealing, FTO / SnO2 / 3PGPCN / FA is formed. 0.9 Cs 0.1 PbI3 thin films were used to prepare perovskite light-absorbing layers with a wavelength of 480-550 nm.

[0034] Step 7: Preparation of the hole transport layer; the hole transport layer was prepared from Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene and stirred at room temperature in the dark for 12 h to prepare a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in step 6 at 5000 rpm for 30 s to form the hole transport layer, resulting in a structure of FTO / SnO2 / 3PGPCN / FA. 0.9 Cs 0.1PbI3 / Spiro-OMeTAD thin film.

[0035] Step 8: Prepare the metal electrode; deposit approximately 80 nm thick gold on the surface of the hole transport layer prepared in step 7 as the metal electrode, resulting in a structure of FTO / SnO2 / 3PGPCN / FA. 0.9 Cs 0.1 PbI3 / Spiro-OMeTAD / Au perovskite solar cells.

[0036] A second aspect of the present invention discloses an FA prepared by the above method. 0.9 Cs 0.1 The structure of a PbI3 perovskite solar cell is shown in Figure 1: from bottom to top, it consists of an FTO substrate, a SnO2 electron transport layer, a 3PGPCN interface modification layer, and a FA layer. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer, Spiro-OMeTAD hole transport layer, and metal electrode.

[0037] The present invention will be further described in detail below with reference to specific examples: Example 1 First, cleaning the FTO glass substrate: cut the FTO glass to a size of 2.5×2.5 cm, mix the glass cleaner and ultrapure water at a volume ratio of 1:100, place the FTO glass in an ultrasonic cleaner and sonicate for 30 min, take it out and rinse the FTO glass and the inner wall of the beaker with ultrapure water, repeat the sonication 3 times, soak the cleaned FTO glass in clean anhydrous ethanol for later use, and blow it dry with an air compressor before use.

[0038] Second, prepare the SnO2 electron transport layer precursor solution and the chlorobenzene solution of 3PGPCN: The method for preparing the SnO2 electron transport layer precursor solution is as follows: Dissolve an appropriate amount of SnO2 colloidal nanoparticles (V / V = 1:6) in deionized water and stir at room temperature for 6-8 hours to ensure homogeneous mixing. The 3PGPCN solution is prepared by dissolving 0.75 mg of purchased 3PGPCN solid in 1 mL of chlorobenzene and stirring at room temperature for 1-2 hours to obtain a 0.75 mg / mL 3PGPCN chlorobenzene solution. Before use, the solution should be filtered through a 0.45 μm filter.

[0039] Third, the SnO2 electron transport layer was prepared: the SnO2 colloidal nanoparticle solution prepared in step 2 was spin-coated onto the surface of the FTO substrate at a spin speed of 3000 rpm for 40 s, followed by annealing at 100 ℃ for 40 min to obtain the SnO2 electron transport layer. Before spin-coating the 3PGPCN chlorobenzene solution, the FTO / SnO2 substrate was treated with ultraviolet ozone for 12 min.

[0040] Fourth, prepare the 3PGPCN modification layer: Spin-coat the 3PGPCN chlorobenzene solution prepared in step 2 onto the surface of the SnO2 electron transport layer obtained in step 3. The spin-coating speed is 3000 rpm and the spin-coating time is 30 s. Then, annealing is performed at a temperature of 100 ℃ for 10 min to obtain the 3PGPCN interface modification layer. Before spin-coating the perovskite precursor solution, the FTO / SnO2 / 3PGPCN substrate is treated with ultraviolet ozone for 12 min.

[0041] Fifth, prepare FA 0.9 Cs 0.1 PbI3 perovskite precursor solution: A 1.0 M FA solution was prepared by dissolving formamidinium hydroiodate (FAI), cesium iodide (CsI), and lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5). 0.9 Cs 0.1 PbI3 perovskite precursor solution: Stir the perovskite precursor solution for 6-12 h, then filter it using a 0.45 μm filter cartridge for later use.

[0042] Sixth, preparation of FA 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer: The perovskite precursor solution prepared in step 5 was spin-coated onto the surface of an FTO / SnO2 / 3PGPCN substrate. The spin-coating process was completed in two stages: the first stage was at 1000 rpm for 10 s; the second stage was at 5000 rpm for 30 s. Annealing was then performed at 120°C. o C, annealing time is 30 min. After annealing, FTO / SnO2 / 3PGPCN / FA is formed. 0.9 Cs 0.1 PbI3 thin film.

[0043] Seventh, preparation of the hole transport layer: The hole transport layer was prepared by Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene and stirred at room temperature in the dark for 12 h to prepare a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in step 6 at a speed of 5000 rpm for 30 s to form a hole transport layer, resulting in a structure of FTO / SnO2 / 3PGPCN / FA. 0.9 Cs 0.1 PbI3 / Spiro-OMeTAD thin film.

[0044] Eighth, prepare the metal electrode: deposit a gold electrode with a thickness of about 80 nm on the surface of the hole transport layer prepared in step 7, resulting in a structure of FTO / SnO2 / 3PGPCN / FA. 0.9 Cs 0.1 A PbI3 / Spiro-OMeTAD / Au perovskite solar cell. The effective active area of ​​the cell is 0.09 cm². 2 The effective area is 0.09 cm². 2 Devices are fabricated using photomasks.

[0045] In this example, a SnO2-based perovskite solar cell modified with 0.75 mg / mL 3PGPCN was prepared.

[0046] Figure 1 shows a schematic diagram of a perovskite solar cell with a liquid crystal modified layer. From bottom to top, the layers are: FTO, SnO2 electron transport layer, 3PGPCN interface modification layer, and FA. 0.9 Cs 0.1 The structure consists of a PbI3 perovskite light-absorbing layer, a Spiro-OMeTAD hole transport layer, and a gold electrode. The concentration of 3PGPCN is 0.75 mg / mL.

[0047] Comparative Example 1 differs from Example 1 in the operations of steps 2 and 4. Specifically, in step 2, a chlorobenzene solution of 3PGPCN was not prepared in Comparative Example 1, and in step 4, a 3PGPCN interface modification layer was not spin-coated; all other steps and parameters were the same.

[0048] As shown in Figure 2, SEM tests on the perovskite films before and after modification with 3PGPCN on the surface of the SnO2 electron transport layer show that after modification with 3PGPCN, the perovskite film exhibits a significant increase in grain size, a smoother and flatter surface, a significant reduction in porosity at grain boundaries, a tighter arrangement of grains, and improved overall density, resulting in superior quality.

[0049] Figure 3 illustrates the interaction between 3PGPCN and SnO2. As shown in Figure (a), after modification with 3PGPCN, Sn3d... 5 / 2 and Sn 3d 3 / 2The peak positions shifted towards lower binding energies by 0.35 eV and 0.36 eV, respectively, indicating an increase in the electron cloud density on the SnO2 surface. This is closely related to the coordination interaction between the cyano group (-CN) in the 3PGPCN molecule and the Sn site. The formation of the coordination bond alters the electronic environment of Sn. As shown in Figure (b), after modification with 3PGPCN, the peak positions of the O-Sn bond (530.65 eV) and HO-Sn bond (531.91 eV) in the SnO2 film shifted towards lower binding energies by 0.30 eV and 0.36 eV, respectively, corresponding to new peak positions of 530.35 eV and 531.55 eV. This is because the interaction between the fluorine atom (-F) in the 3PGPCN molecule and the hydroxyl group on the SnO2 surface effectively reduces surface oxygen vacancies (V... O )concentration.

[0050] Figure 4 illustrates the interaction between 3PGPCN and PbI2. As can be seen from the figure, compared to the pure PbI2 sample, the Pb 4f of the 3PGPCN / PbI2 mixture is significantly higher. 5 / 2 and Pb 4f 7 / 2 The corresponding peak positions shifted towards higher binding energy directions by 0.37 eV (143.37 eV) and 0.29 eV (138.44 eV), respectively. The changes in the Pb binding energy indicate a strong interaction between the 3PGPCN molecule and PbI2, leading to the Pb... 2+ The electron cloud density decreases.

[0051] Figure 5 further clarifies the interaction between 3PGPCN and PbI2. The figure shows that after mixing 3PGPCN with PbI2, the peak position of the cyano group (C≡N) shifts to a higher wavenumber by 9 cm⁻¹. -1 Up to 2234 cm -1 The peak position of the fluorine atom (-F) shifts to a higher wavenumber by 8 cm⁻¹ -1 Up to 1192 cm -1 This phenomenon is attributed to the interaction between the C≡N and F atoms in the 3PGPCN molecule and the uncoordinated Pb atoms in PbI₂. 2+ Coordination occurs, leading to changes in the vibrational frequencies of chemical bonds.

[0052] Figure 6 shows the electron mobility (Figure a) and conductivity (Figure b) of unmodified and 3PGPCN-modified SnO2 films. As shown in Figure 6, the electron mobility (Figure a) and conductivity (Figure b) of the 3PGPCN-modified SnO2 film are both better than those of the unmodified film, indicating that the electrical performance of the electron transport layer is improved. This is due to the increased transport efficiency of photogenerated carriers, which ultimately improves the electrical performance of the electron transport layer.

[0053] Figure 7 shows the photoluminescence (PL) spectra of the perovskite films with and without modification of the SnO2 electron transport layer surface using 3PGPCN. The figure shows that the PL intensity is significantly reduced after 3PGPCN modification, and the PL peak exhibits a blue shift. The SnO2 / 3PGPCN / PVK film shows a more significant PL quenching phenomenon, indicating that the carrier extraction efficiency at the SnO2 / 3PGPCN / PVK interface is improved, and the nonradiative recombination of the perovskite film is effectively suppressed. This may be due to the improved band alignment and conductivity of the SnO2 film after 3PGPCN modification. Simultaneously, after optimization, the number of defects at the buried interface is significantly reduced, leading to the blue shift of the PL peak.

[0054] Figure 8 shows the TRPL spectra of perovskite films with and without modification of the SnO2 electron transport layer surface with 3PGPCN. As shown in Figure 8, compared with the unmodified perovskite film, the average carrier lifetime of the film modified with 3PGPCN on the SnO2 electron transport layer surface is shortened, indicating that the optimized film successfully suppresses the non-radiative recombination channel at the interface, which helps the extraction and transport of electrons from the perovskite to the electron transport layer.

[0055] Figure 9 shows a comparison of the UPS of unmodified and 3PGPCN-modified SnO2 films. As shown in Figure 9, the conduction band and Fermi level of the SnO2 film are improved after 3PGPCN modification. The SnO2 film modified with 3PGPCN is also more compatible with the perovskite layer. This is beneficial to reduce the electron transfer barrier and interface recombination loss, thereby enhancing the efficiency of interface charge transport and extraction, and improving the open circuit voltage and fill factor of the perovskite solar cell.

[0056] Figure 10 shows the JV curves of perovskite solar cells with and without modification of the SnO2 electron transport layer surface, and with modification of 3PGPCN. Specific parameters are shown in Table 1. As shown in Figure 10, the fill factor and open-circuit voltage of the perovskite solar cell are significantly improved after modification of the SnO2 electron transport layer surface with 3PGPCN, reaching 81.67% and 1.211 V, respectively. Simultaneously, the fabricated device achieves a high photoelectric conversion efficiency of 25.46%.

[0057] Figure 11 shows the stability of the device efficiency of unmodified and modified 3PGPCN devices at an air temperature of 25 ℃ and a humidity of about 30%. As shown in Figure 11, the device optimized with 3PGPCN can still maintain 94.6% of the initial efficiency after 1632 h of aging, which shows good stability.

[0058] Table 1 J-V Curve Parameters

[0059] Example 2: In this example, a 0.25 mg / mL 3PGPCN chlorobenzene solution was spin-coated onto an FTO / SnO2 substrate. The perovskite solar cell modified with 0.25 mg / mL 3PGPCN achieved an open-circuit voltage of 1.162 V, a fill factor of 80.13%, and a voltage drop of 24.84 mA / cm². 2 The current density is 23.10%, and the photoelectric conversion efficiency is 23.10%. Parameters and steps not involved in this embodiment are the same as in Embodiment 1.

[0060] Example 3: In this example, a 0.50 mg / mL 3PGPCN chlorobenzene solution was spin-coated onto an FTO / SnO2 substrate. The perovskite solar cell modified with 0.50 mg / mL 3PGPCN achieved an open-circuit voltage of 1.171 V, a fill factor of 80.89%, and a capacitance of 25.06 mA / cm². 2 The current density is 23.85%, and the photoelectric conversion efficiency is 23.85%. Parameters and steps not involved in this embodiment are the same as in Embodiment 1.

[0061] Example 4: In this example, a 1.0 mg / mL 3PGPCN chlorobenzene solution was spin-coated onto an FTO / SnO2 substrate. The perovskite solar cell modified with 1.0 mg / mL 3PGPCN achieved an open-circuit voltage of 1.154 V, a fill factor of 80.02%, and a capacitance of 25.20 mA / cm². 2 The current density is 23.39%, and the photoelectric conversion efficiency is 23.39%. Parameters and steps not involved in this embodiment are the same as in Embodiment 1.

[0062] Example 5 In this example, the spin coating speed of the chlorobenzene solution of 3PGPCN was 2000 rpm and the spin coating time was 30 s. The parameters and steps not involved in this example are the same as those in Example 1.

[0063] Example 6 In this example, the spin coating speed of 3PGPCN chlorobenzene solution was 4000 rpm and the spin coating time was 30 s. The parameters and steps not involved in this example are the same as those in Example 1.

[0064] Example 7 In this example, after spin-coating chlorobenzene solution of 3PGPCN, annealing treatment was performed at a temperature of 100 °C for 13 min. Parameters and steps not involved in this example are the same as in Example 1.

[0065] Example 8 In this example, after spin-coating chlorobenzene solution of 3PGPCN, annealing treatment was performed at a temperature of 100 °C for 15 min. Parameters and steps not involved in this example are the same as in Example 1.

[0066] Example 9 In this example, the spin-coating process of the perovskite precursor solution was completed in two stages. The first stage involved a spin-coating speed of 1500 rpm for 10 seconds; the second stage involved a spin-coating speed of 4000 rpm for 30 seconds. Annealing was then performed at a temperature of 120°C. o C, annealing time is 30 min. After annealing, FTO / SnO2 / 3PGPCN / FA is formed. 0.9 Cs 0.1 For the PbI3 thin film, the parameters and steps not involved in this embodiment are the same as those in Example 1.

[0067] Example 10: In this example, the spin-coating process of the perovskite precursor solution was completed in two stages. The first stage involved a spin-coating speed of 2000 rpm for 10 seconds; the second stage involved a spin-coating speed of 4500 rpm for 30 seconds. Annealing was then performed at a temperature of 120°C. o C, annealing time is 30 min. After annealing, FTO / SnO2 / 3PGPCN / FA is formed. 0.9 Cs 0.1 For the PbI3 thin film, the parameters and steps not involved in this embodiment are the same as those in Example 1.

[0068] Example 11 In this example, when the SnO2 colloidal nanoparticle solution was spin-coated onto the surface of the FTO substrate, the spin-coating speed was 2500 rpm, the spin-coating time was 30 s, and the annealing time was 35 min.

[0069] Example 12 In this example, when the SnO2 colloidal nanoparticle solution was spin-coated onto the surface of the FTO substrate, the spin-coating speed was 4000 rpm, the spin-coating time was 35 s, and the annealing time was 35 min.

[0070] Example 13 In this example, 3PGPCN was not used as an interface modification material, but was directly added to the perovskite precursor solution as an additive to achieve doping studies on the perovskite bulk phase.

[0071] Step 1, Cleaning the FTO glass substrate: Cut the FTO glass to a size of 2.5×2.5 cm. Mix the glass cleaner and ultrapure water at a volume ratio of 1:100. Place the FTO glass in an ultrasonic cleaner and sonicate for 30 minutes. Remove and rinse the FTO glass and the inner wall of the beaker with ultrapure water. Repeat the sonication 3 times. Soak the cleaned FTO glass in clean anhydrous ethanol for later use. Dry it with an air compressor before use.

[0072] Step 2, Preparation of SnO2 electron transport layer precursor solution: Method for preparing SnO2 electron transport layer precursor solution: Dissolve an appropriate amount of SnO2 colloidal nanoparticles (V / V=1:6) in deionized water, stir at room temperature for 6-8 h to ensure uniform mixing, and then set aside.

[0073] Step 3, Preparation of the SnO2 electron transport layer: The SnO2 colloidal nanoparticle solution prepared in Step 2 was spin-coated onto the surface of the FTO substrate at a spin speed of 3000 rpm for 40 s. Following this, annealing was performed at 100℃ for 40 min to obtain the SnO2 electron transport layer. Before spin-coating the perovskite precursor solution, the FTO / SnO2 substrate was treated with UV ozone for 12 min.

[0074] Step 4, prepare FA 0.9 Cs 0.1 PbI3 perovskite precursor solution: Formamidinium hydroiodate (FAI), cesium iodide (CsI), lead iodide (PbI2) (molar ratio = 0.9:0.1:1.0) and 1.0 mg of 3PGPCN solid were dissolved in a mixed solvent of DMF and DMSO (V / V = 8.5:1.5) to prepare a 1.0 M FAI solution. 0.9 Cs 0.1 The PbI3 bulk doped perovskite precursor solution was stirred at room temperature for 6-12 h, and then filtered using a 0.45 μm filter cartridge for later use.

[0075] Step 5, Prepare FA 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer: The bulk-doped perovskite precursor solution prepared in step 4 was spin-coated onto the surface of an FTO / SnO2 substrate. The spin-coating process was completed in two stages: the first stage was at a spin speed of 1000 rpm for 10 s; the second stage was at a spin speed of 5000 rpm for 30 s. Annealing was then performed at a temperature of 120°C. o C, annealing time is 30 min. After annealing, FTO / SnO2 / FA is formed. 0.9 Cs 0.1 PbI3 (3PGPCN) thin film.

[0076] Step 6, Preparation of the hole transport layer: The hole transport layer was prepared using Spiro-OMeTAD. Spiro-OMeTAD powder (90 mg), lithium salt (22 μL), and t-BP (36 μL) were dissolved in 1 mL of chlorobenzene and stirred at room temperature in the dark for 12 h to prepare a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated onto the perovskite film prepared in step 5 at 5000 rpm for 30 s to form the hole transport layer, resulting in a structure of FTO / SnO2 / FA. 0.9 Cs 0.1 Thin films of PbI3(3PGPCN) / Spiro-OMeTAD.

[0077] Step 7, fabrication of the metal electrode: Gold with a thickness of approximately 80 nm is deposited on the surface of the hole transport layer prepared in Step 6 as the metal electrode, resulting in a structure of FTO / SnO2 / FA. 0.9 Cs 0.1 A perovskite solar cell using PbI3 (3PGPCN) / Spiro-OMeTAD / Au. The effective active area of ​​the cell is 0.09 cm². 2 The effective area is 0.09 cm². 2 Devices are fabricated using photomasks.

[0078] In this example, a 1.0 mg / mL 3PGPCN bulk-doped perovskite solar cell was fabricated. An open-circuit voltage of 1.169 V, a fill factor of 82.33%, and a capacitance of 25.56 mA / cm² were obtained. 2 The current density is 24.59%, and the photoelectric conversion efficiency is 24.59%.

[0079] Example 14 used 0.5 mg of 3PGPCN as an additive in the perovskite precursor solution, prepared using the same method as step 4 in Example 9. The resulting perovskite bulk-doped solar cell had a concentration of 0.5 mg / mL 3PGPCN. It achieved an open-circuit voltage of 1.152 V, a fill factor of 81.62%, and a capacitance of 25.42 mA / cm². 2 The current density is 23.89%, and the photoelectric conversion efficiency is 23.89%. Parameters and steps not involved in this embodiment are the same as in Embodiment 13.

[0080] Example 15 used 2.0 mg of 3PGPCN as an additive in the perovskite precursor solution, prepared using the same method as step 4 in Example 9. A 2.0 mg / mL 3PGPCN-doped perovskite bulk solar cell was obtained. The cell achieved an open-circuit voltage of 1.165 V, a fill factor of 82.06%, and a capacitance of 25.33 mA / cm². 2The current density is 24.20%, and the photoelectric conversion efficiency is 24.20%. Parameters and steps not involved in this embodiment are the same as in Embodiment 13.

[0081] Example 16 used 4.0 mg of 3PGPCN as an additive in the perovskite precursor solution, prepared using the same method as step 4 in Example 9. A 4.0 mg / mL 3PGPCN-doped perovskite bulk solar cell was obtained. The cell achieved an open-circuit voltage of 1.161 V, a fill factor of 81.45%, and a capacitance of 25.34 mA / cm². 2 The current density is 23.98%, and the photoelectric conversion efficiency is 23.98%. Parameters and steps not involved in this embodiment are the same as in Embodiment 13.

[0082] As can be seen from the above examples, in Examples 13-16, 3PGPCN was added to the perovskite precursor solution as a bulk additive. When used as a bulk doping additive, the effect showed a pattern of first increasing and then decreasing, with 1.0 mg / mL being the optimal concentration. Below this concentration, the passivation effect was insufficient, while above this concentration, it had a negative effect, leading to a decrease in battery performance. Furthermore, compared to using it as an interface modification layer, the open-circuit voltage improvement was not significant, and the photoelectric conversion efficiency was low. Comparing Examples 1-12 as an interface layer and Examples 13-16, it can be seen that the optimal efficiency of interface modification (25.46%) is 0.87% higher than the optimal efficiency of bulk doping (24.59%), representing a relative improvement of 3.54%.

[0083] Table 1 Comparison of Example 1 and Example 13

[0084] As can be seen from the comparison in the table above, the data for interface modification are all superior to those for bulk doping.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a perovskite solar cell with a liquid crystal modified layer, characterized in that, Includes the following steps: S1, a SnO2 colloidal nanoparticle solution is spin-coated onto a glass substrate, and an electron transport layer is obtained after annealing; S2, 3PGPCN solid powder is dissolved in chlorobenzene, stirred to obtain a modification layer solution, and the modification layer solution is spin-coated onto the electron transport layer, and a liquid crystal modification layer is obtained after annealing; the 3PGPCN solid powder is 2'-fluoro-4”-propyl-[1,1';4',1”-terphenyl]-4-carboxynitrile, with the following structural formula: S3, FA 0.9 Cs 0.1 A PbI3 perovskite precursor solution was spin-coated onto a liquid crystal modification layer, and then annealed to obtain FA. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer; S4, in FA 0.9 Cs 0.1 Spiro fabrication on PbI3 perovskite light-absorbing layer OMeTAD hole transport layer; S5, in Spiro Metal electrodes were fabricated on the OMeTAD hole transport layer to obtain a perovskite solar cell with a liquid crystal modification layer.

2. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S1, the solute of the SnO2 colloidal nanoparticle solution is SnO2 colloidal nanoparticles, and the solvent is water; in S1, the annealing temperature is 100 ℃, and the annealing time is 30-40 min.

3. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S2, the concentration of the modified layer solution is 0.25-1.0 mg / mL.

4. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S2, the spin coating speed of the modified layer solution is 2000-4000 rpm, and the spin coating time is 30 s.

5. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S2, the annealing temperature is 100 ℃ and the annealing time is 10-15 min.

6. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S3, the concentration of the perovskite precursor solution is 1.0 M.

7. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S3, the perovskite precursor solution is spin-coated in two stages: the first stage has a rotation speed of 1000-2000 rpm and a time of 10 s; the second stage has a rotation speed of 4000-5000 rpm and a time of 30 s.

8. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S4, the Spiro The rotation speed of the OMeTAD hole transport layer is 5000 rpm, and the spin coating time is 30 s.

9. The method for preparing a perovskite solar cell with a liquid crystal modified layer according to claim 1, characterized in that, In S1, the glass substrate is FTO glass, and in S5, the metal electrode is gold.

10. A perovskite solar cell with a liquid crystal modified layer, characterized in that, This includes, from bottom to top, a release substrate, a SnO2 electron transport layer, a 3PGPCN liquid crystal modification layer, and a FA layer stacked sequentially. 0.9 Cs 0.1 PbI3 perovskite light-absorbing layer, Spiro OMeTAD hole transport layer and metal electrode; the 3PGPCN in the 3PGPCN liquid crystal modification layer is 2'-fluoro-4”-propyl-[1,1';4',1”-terphenyl]-4-carboxynitrile, with the following structural formula: 。

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