Hole transport layer and preparation method and application thereof
By forming a hole transport layer through self-assembly of a monolayer and covalent bonding with amino acids, the stability and efficiency issues of the hole transport layer in perovskite solar cells were solved, achieving efficient charge transport and improved cell performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANGZHOU UNIV
- Filing Date
- 2026-02-12
- Publication Date
- 2026-05-08
AI Technical Summary
Existing hole transport layers in perovskite solar cells suffer from large open-circuit voltage loss and low device efficiency, mainly due to the tendency of self-assembled monolayers to aggregate in solution and the lack of tight bonding with the substrate, resulting in insufficient coverage.
Hole transport layers are formed by covalently bonding self-assembled monolayers containing oxygen functional groups with amino and/or carboxyl groups of amino acids. Self-assembled monolayers such as (2-(9H-carbazole-9-yl)ethyl)phosphonic acid and amino acids such as L-2-aminohexanoic acid are preferably used to adjust the work function of the hole transport layer and improve stability and transport efficiency.
It significantly improves the stability and transport efficiency of the hole transport layer, reduces surface defects in the perovskite layer, promotes charge transfer, and enhances the photoelectric conversion efficiency and stability of perovskite solar cells.
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Figure CN122003017A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of perovskite solar cell technology, and particularly relates to a hole transport layer, its preparation method and application. Background Technology
[0002] Perovskite solar cells (PSCs) utilize organic-inorganic halide perovskites as light-absorbing materials, offering advantages such as low cost, simple fabrication processes, and high photoelectric conversion potential, making them a promising research hotspot in the photovoltaic field. Their core structure typically comprises five parts from bottom to top: a substrate, a hole transport layer (HTL), a perovskite layer, an electron transport layer, and a metal electrode. Among these, the hole transport layer is the key functional layer, efficiently extracting and separating charges to improve the utilization rate of photogenerated carriers, promoting hole transport to reduce charge accumulation and loss, and simultaneously suppressing charge recombination to reduce interface and bulk losses.
[0003] The application of self-assembled monolayers (SAMs) as hole transport layers has greatly boosted the performance of power storage cells (PSCs). SAM molecules can form a uniform and ordered monolayer on the electrode surface through simple solution processing. This effectively modulates the electrode work function and promotes hole extraction and transport, thereby reducing device series resistance and improving fill factor and photoelectric conversion efficiency. However, SAMs can aggregate in solution, and the loose bonding between phosphate groups and the metal oxide substrate can lead to incomplete HTL coverage, ultimately resulting in a significant decrease in battery performance.
[0004] Therefore, constructing a high-quality hole transport layer to improve the power generation efficiency of batteries has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] This application discloses a hole transport layer, its fabrication method, and its application, aiming to solve the technical problems of large open-circuit voltage loss and low device efficiency of existing hole transport layers.
[0006] To achieve the above objectives, the technical solution of this application is: The first aspect of this application provides a hole transport layer, which is formed by self-assembled monolayer containing oxygen-containing functional groups and covalent bonding of amino and / or carboxyl groups of amino acids.
[0007] Preferably, in conjunction with the first aspect, the self-assembled monolayer comprises one or more of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid, and (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid.
[0008] Preferably, in conjunction with the first aspect, the amino acid includes one or more of L-2-aminoadipic acid, L-alanine, L-2-aminobutyric acid, L-valine, and (S)-2-aminooctanoic acid.
[0009] Preferably, in conjunction with the first aspect, the molar ratio of the self-assembled monolayer to the amino acid is (9-6):(1-4).
[0010] A second aspect of this application provides a perovskite solar cell, comprising a substrate, a hole transport layer as described in the first aspect, a perovskite layer, an electron transport layer, and an electrode.
[0011] In conjunction with the second aspect, preferably, the perovskite layer is an organic-inorganic hybrid perovskite with the general formula ABX3; Where: A is methylamine ion, formamidinium ion, or cesium ion; B is either lead ion or tin ion; X is an iodide ion, bromide ion, or chloride ion; The electron transport layer comprises one or more of tin oxide, titanium oxide, or zinc oxide; The electrode comprises one or more of silver, copper, gold, and carbon.
[0012] A third aspect of this application provides a method for fabricating the perovskite solar cell described in the second aspect, the method comprising: After depositing a hole transport layer on the substrate; A perovskite layer is deposited on the hole transport layer and then passivated. An electron transport layer is deposited on the perovskite layer; Electrodes are deposited on the electron transport layer.
[0013] Preferably, in conjunction with the third aspect, after depositing a hole transport layer on the substrate, the method includes: A self-assembled monolayer solution is mixed with an amino acid solution, and the resulting mixed solution is coated onto the substrate surface for deposition to form the hole transport layer.
[0014] Preferably, in conjunction with the third aspect, the concentration of the self-assembled monolayer solution is 0.5-1 mg / mL; The concentration of the amino acid solution is 0.5-1 mg / mL.
[0015] Preferably, in conjunction with the third aspect, the deposition method includes one of magnetron sputtering, thermal evaporation, electron beam evaporation, screen printing, blade coating, slot coating, or spraying.
[0016] Compared with the prior art, the advantages or beneficial effects of the embodiments of this application include at least the following: The hole transport layer provided in this application is made by chemically bonding a self-assembled monolayer containing oxygen-containing functional groups with amino acids. On the one hand, it improves the stability of the SAM solution and enhances the transport efficiency of the hole transport layer, while reducing surface defects in the perovskite layer and promoting charge transfer, thereby improving the efficiency and stability of the battery. On the other hand, by selecting amino acids with different chain lengths, the work function of the hole transport layer can be adjusted to precisely match the valence band energy level of the perovskite layer, significantly reducing the interfacial charge recombination resistance and greatly improving battery performance. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell provided in an embodiment of this application; Among them, 1-substrate, 2-hole transport layer, 3-perovskite layer, 4-electron transport layer, 5-electrode; Figure 2 Infrared spectrum of A2-perovskite solar cell prepared in Example 2 of this application; Figure 3 The infrared spectrum of the A3-perovskite solar cell prepared in Example 3 of this application; Figure 4 Infrared spectrum of A4-perovskite solar cell prepared in Example 4 of this application; Figure 5 Infrared spectrum of A5-perovskite solar cell prepared in Example 5 of this application; Figure 6 JV curves for perovskite solar cells fabricated in Examples 1, 6, 7 and Comparative Example 1 of this application; Figure 7The JV curves are for perovskite solar cells prepared in Examples 2-5 and Comparative Example 1 of this application. Detailed Implementation
[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0020] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0021] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.
[0022] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.
[0024] It should be noted that all raw materials and / or reagents in the embodiments of this application were purchased on the market or prepared according to conventional methods known to those skilled in the art.
[0025] In this article, self-assembled monolayers are abbreviated as SAM.
[0026] In a first aspect, embodiments of this application provide a hole transport layer, which is formed by covalent bonding of a self-assembled monolayer containing oxygen-containing functional groups and amino and / or carboxyl groups of amino acids.
[0027] In some specific embodiments, the self-assembled monolayer containing oxygen functional groups is preferably (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Me-2PACz), or (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (4PACz). Cz), [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz), and (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz); wherein the oxygen-containing functional groups specifically include hydroxyl (-OH), carboxyl (-COOH), ether bond (COC), epoxy (-CH(O)CH2-), sulfonic acid (-SO3H), etc., which are the core oxygen-containing functional groups of this type of SAMs.
[0028] It should be noted that this application does not impose any particular limitation on self-assembled monolayers containing oxygen-containing functional groups, as long as they can form covalent bonds with the amino and / or carboxyl groups of amino acids.
[0029] In some specific embodiments, this application does not particularly limit the type of amino acid. The amino acid may contain functional groups such as amino, carboxyl, amide, and thiol groups, including one or more of L-2-aminoadipic acid, L-alanine, L-2-aminobutyric acid, L-valine, and (S)-2-aminooctanoic acid. It can be prepared by compounding with SAM solution. All can be compounded with the preparation process of this application. This application does not make any special limitation. As long as it can improve the performance of the hole transport layer, it is acceptable.
[0030] In some specific embodiments, the substrate is preferably conductive glass. This application does not particularly limit the conductive glass; it can be fluorine-doped tin oxide transparent conductive glass or conductive glass coated with an indium tin oxide film, as long as it achieves the conductive function.
[0031] It should be noted that 0.5 mg / ml L-2-aminohexanoic acid (Lα) aqueous solution and 0.5 mg / ml MeO-2PACz IPA solution were mixed at molar ratios of 9:1, 8:2, and 6:4, with corresponding volumes of water added to maintain a consistent IPA to water volume ratio in the total solution. The mixed solution was then spin-coated onto an FTO conductive glass substrate and annealed to form a composite hole transport layer. Simultaneously, four amino acids with different chain lengths and containing similar functional groups—L-alanine (short chain), L-2-aminobutyric acid (medium chain length), L-valine (medium chain length), and (S)-2-aminooctanoic acid (long chain)—were selected and their effects on the work function of SAM solution were studied using the same process. This system achieves performance breakthroughs through the multiple effects of amino acids: functional groups deprotonate SAM molecules, making them charged, and like-charge repulsion inhibits aggregation, thus improving the stability of the SAM solution; functional groups reduce perovskite surface defects; and synergistic optimization of energy level matching adjusts the work function of the SAM-based hole transport layer, improving hole transport efficiency. The resulting perovskite solar cell achieved a photoelectric conversion efficiency of up to 25.65%, demonstrating its simple process, broad material applicability, and promising application prospects.
[0032] It should be noted that the composite hole transport layer obtained in this application uses amino acids with different functional groups combined with SAM solution as the hole transport layer material, which can give full play to the advantages of both: these functional groups on the amino acids can deprotonate the molecules in the SAM solution, thereby making the molecules in the SAM solution charged. Since like charges repel each other, the molecules in the SAM solution will be more dispersed, effectively preventing the aggregation of SAM solution. It can be seen that these functional groups improve the stability of SAM solution. Secondly, these amino acids containing functional groups play a regulatory role in the hole transport layer made of SAM solution, optimizing the hole transport efficiency of the hole transport layer.
[0033] It should be noted that the hole transport layer preparation method provided in this application, compared with the hole transport layer preparation method using SAM or amino acid solution alone, has improved efficiency and stability while being simple and easy to implement, and has good prospects.
[0034] Secondly, this application protects a perovskite solar cell, comprising a substrate, a hole transport layer as described in the first aspect, a perovskite layer, an electron transport layer, and electrodes. The substrate is any one of indium tin oxide (ITO) and fluorine-doped indium tin oxide (FTO), but is not limited to the substrates listed above. The perovskite layer is an organic-inorganic hybrid perovskite with the general formula ABX3; wherein: A is methylamine ion, formamidinium ion, or cesium ion; B is lead ion or tin ion; and X is iodide ion, bromide ion, or chloride ion. This general formula covers the mainstream organic-inorganic hybrid perovskite systems in the prior art and has wide applicability, and is not limited to the perovskite layers listed above. The electron transport layer includes one or more of tin oxide, titanium oxide, or zinc oxide; all are mainstream electron transport materials for perovskite solar cells, possessing high electron mobility and good compatibility with the perovskite layer, but are not limited to the electron transport layers listed above. The electrodes include one or more of silver, copper, gold, and carbon, but are not limited to the electrodes listed above.
[0035] Thirdly, this application provides a method for fabricating the perovskite solar cell described in the second aspect, the method comprising: depositing a hole transport layer on a substrate; depositing a perovskite layer on the hole transport layer and performing passivation treatment; depositing an electron transport layer on the perovskite layer; and depositing an electrode on the electron transport layer.
[0036] In some specific embodiments, after depositing the hole transport layer on the substrate, the process includes: mixing a self-assembled monolayer solution with an amino acid solution, depositing the resulting mixed solution on the substrate surface, and annealing to form the hole transport layer. SAM molecules (containing oxygen-containing functional groups) and amino acid molecules (containing amino / carboxyl groups) are first mixed in the solution phase to ensure sufficient contact between the two groups, providing sufficient and uniform reaction sites for the covalent bonding reaction in the subsequent annealing process. Co-deposition enables the simultaneous directional spreading of the two molecules on the substrate surface, constructing an ordered film layer. The temperature provided by annealing activates the covalent bonding reaction, transforming weak intermolecular interactions such as hydrogen bonds or van der Waals forces into stable covalent bonds. Simultaneously, annealing removes residual solvent and trace impurities from the mixed solution, making the film layer denser, reducing porosity defects, and improving the structural stability of the hole transport layer.
[0037] In some specific embodiments, the concentration of the self-assembled monolayer solution is preferably 0.5-1 mg / mL; the concentration of the amino acid solution is preferably 0.5-1 mg / mL, more preferably 0.5 mg / mL. Controlling the SAM solution concentration at 0.5-1 mg / mL allows for the formation of a dense and uniform monolayer, avoiding discontinuous film formation at too low a concentration and SAM molecule aggregation at too high a concentration. Within this concentration range, SAM molecules can be fully anchored and uniformly covered with the conductive glass substrate, achieving optimal results. The amino acid solution concentration is preferably 0.5-1 mg / mL, enabling full covalent bonding with SAM molecules. This avoids the inability to effectively prevent SAM aggregation at too low a concentration, while excessively high concentrations result in a large amount of residual amino acids, leading to reduced hole transport efficiency. Therefore, limiting the concentration can effectively improve the transport efficiency and interface stability of the hole transport layer.
[0038] In some specific embodiments, the deposition method preferably includes one of magnetron sputtering, thermal evaporation, electron beam evaporation, screen printing, blade coating, slot coating, or spraying. This application does not limit the deposition method; any method that achieves the deposition objective is acceptable. Process parameters can be adjusted according to the thickness of each target layer.
[0039] The technical solution of this application will be further described below with reference to specific embodiments.
[0040] Example 1 This embodiment provides a method for preparing Al-perovskite solar cells, such as... Figure 1 The structure shown specifically includes: S101: Clean the FTO conductive glass by ultrasonication twice: 30 min with laundry detergent, 30 min with pure water, and 30 min with alcohol. Perform single-step spin coating on the conductive glass surface. Using a pipette, drop a composite solution of 80 μL of 0.5 mg / ml L-2-aminohexanoic acid (Lα) aqueous solution and 0.5 mg / ml MeO-2PACz IPA composite hole layer (molar ratio 9:1) directly above the FTO glass surface, ensuring uniform distribution. After activating vacuum and waiting 3 seconds, start spin coating at 4000 rpm, 30 s, and 2000 A. After spin coating, perform annealing at 100 °C for 10 min.
[0041] S102: After the glass slide coated with the hole transport layer has cooled, a two-step spin coating process is performed. 70 μL of 1.6 MFA... 0.95 Cs 0.05A perovskite precursor solution of PbI3 + 5% PbI3 + 15% MACl (using a 4:1 DMF:DMSO mixture as the solvent) was uniformly distributed on the hole transport layer under the same operating conditions, and spin-coated at 2000 rpm, 10 s, 1000 a and 4000 rpm, 45 s, 2000 a. At the last 5 s of spin-coating, 180 μL of the antisolvent CB was added dropwise. After spin-coating, annealing was performed at 100 °C for 60 min. After cooling, a phenylethyl ammonium iodide (PEAI) passivating agent was dynamically spin-coated at 4000 rpm, 30 s, 2000 a, without further annealing.
[0042] S103: Evaporated C 60 (20 nm), BCP (8 nm), control the evaporation rate to be maintained between 0.1 and 0.2, after the rate stabilizes, open the baffle, start the rotation function and activate PID managed control, wait for the film thickness to reach 20 nm and 8 nm. Wait for C 60 Cool the glass to 150 ℃ and BCP to 80 ℃. Remove the glass slide and scrape a 1-2 mm wide strip on both sides, with the scraper direction perpendicular to the etching line.
[0043] S104: After scraping both sides, silver electrodes are deposited, with a thickness of 100 nm. After the current and voltage drop to almost zero, the electrode is removed, which is the Al-perovskite solar cell.
[0044] Example 2 This embodiment provides a method for preparing A2-perovskite solar cells. The component ratios, preparation operations, and process parameters are basically the same as in Example 1. The difference is that in step S101 of this embodiment, 0.5 mg / ml L-alanine (LA) and 0.5 mg / ml SAM composite hole layer solution are mixed in a molar ratio of 9:1 to obtain A2-perovskite solar cells.
[0045] Example 3 This embodiment provides a method for preparing A3-perovskite solar cells. The component ratios, preparation operations, and process parameters are basically the same as in Example 1. The difference is that in step S101 of this embodiment, 0.5 mg / ml L-2-aminobutyric acid (L2) and 0.5 mg / ml SAM composite hole layer solution are mixed in a molar ratio of 9:1 to obtain A3-perovskite solar cells.
[0046] Example 4 This embodiment provides a method for preparing A4-perovskite solar cells. The component ratios, preparation operations, and process parameters are basically the same as in Example 1. The difference is that in step S101 of this embodiment, 0.5 mg / ml L-valine (LN) and 0.5 mg / ml SAM composite hole layer solution are mixed in a molar ratio of 9:1 to obtain A4-perovskite solar cells.
[0047] Example 5 This embodiment provides a method for preparing A5-perovskite solar cells. The component ratios, preparation operations, and process parameters are basically the same as in Example 1. The difference is that in step S101 of this embodiment, 0.5 mg / ml (S)-2-aminooctanoic acid (S2) and 0.5 mg / ml SAM composite hole layer solution are mixed to obtain A5-perovskite solar cells.
[0048] Example 6 This embodiment provides a method for preparing A6-perovskite solar cells. The component ratios, preparation operations, and process parameters are basically the same as in Example 1. The difference is that in step S101 of this embodiment, the molar ratio of 0.5 mg / ml L-2-aminoadipic acid aqueous solution and 0.5 mg / ml SAM composite hole layer solution is 6:4 to obtain A6-perovskite solar cells.
[0049] Example 7 This embodiment provides a method for preparing A7-perovskite solar cells. The component ratios, preparation operations, and process parameters are basically the same as in Example 1. The difference is that in step S101 of this embodiment, the molar ratio of 0.5 mg / ml L-2-aminoadipic acid aqueous solution and 0.5 mg / ml SAM composite hole layer solution is 8:2 to obtain A7-perovskite solar cells.
[0050] Meanwhile, to verify the overall performance of the perovskite solar cells prepared in the above embodiments, this application provides the following comparative examples for detailed illustration.
[0051] Comparative Example 1 In this comparative example, the SAM solution without amino acid modification was used as a blank control group: In step S101, 0.5 mg / ml MeO-2PACz IPA solution was used alone as a blank control cell, denoted as B0-perovskite solar cell.
[0052] according to Figure 1As shown, the inverted perovskite solar cell structure provided in this application, from bottom to top, consists of: an FTO conductive glass substrate, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode. The hole transport layer is a composite of functional amino acids and SAM solution prepared in the examples.
[0053] To investigate the bonding mechanism between amino acids introduced into SAM solution and the cells, four amino acids with different chain lengths but similar functional groups were selected. Specifically, A1-perovskite solar cells, A2-perovskite solar cells, A3-perovskite solar cells, and A4-perovskite solar cells prepared in Examples 2, 3, 4, and 5, respectively, were subjected to infrared spectroscopy. The test results are shown in Figures 2-5. In infrared spectroscopy analysis, wavenumber (unit: cm⁻¹) was used as the unit of measurement. -1 The x-axis represents the x-axis and the y-axis represents the transmittance (in au).
[0054] according to Figure 2 The image shown is an infrared spectrum of an A2-perovskite solar cell, where LA (blue curve) is located between 900-1000 cm⁻¹. -1 The characteristic peaks of P-OH in the region (marked by dashed lines) completely disappear in the SAM+LA mixed sample (red curve); meanwhile, the characteristic peak of NH in pure LA (1600 cm⁻¹) disappears completely. -1 The signal weakens after mixing (nearby). Combined with the disappearance of the free -OH and carbonyl peaks of LA, it can be determined that the P-OH and NH functional groups of LA form hydrogen bonds with the COC (methoxy) oxygen-containing group of SAM. The hydrogen bonding weakens the vibrational characteristics of these functional groups, resulting in the disappearance of their characteristic peaks or a weakening of the signal.
[0055] according to Figure 3 The image shown is an infrared spectrum of an A3-perovskite solar cell, where the NH characteristic peak (1600 cm⁻¹) of L2 (blue curve) is visible. -1 The area near the target sample (red curve) shows a significant displacement, and the displacement is 900-1000 cm. -1 The intensity of the characteristic peak of the P-OH group in the interval decreased significantly; combined with the 1584 cm⁻¹ peak of L2 in the figure. -1 The disappearance of the characteristic peaks indicates that the NH and P-OH groups of L2 formed hydrogen bonds with the oxygen-containing groups of SAM. The hydrogen bonds changed the chemical environment of these functional groups, resulting in the shift and weakening of their characteristic peaks.
[0056] according to Figure 4 The image shown is an infrared spectrum of an A4-perovskite solar cell, where LN (blue curve) is at 1600 cm⁻¹. -1The NH characteristic peaks in the vicinity show a significant signal attenuation in the SAM+LN mixed sample (red curve), while the 900-1000 cm⁻¹ peaks are also significantly reduced. -1 The P-OH characteristic peak in the region no longer has obvious features. This is consistent with the 1582.53 cm⁻¹ peak for LN in previous data. -1 The consistent disappearance of characteristic peaks proves that the NH and P-OH functional groups of LN form hydrogen bonds with the oxygen-containing groups of SAM.
[0057] according to Figure 5 The image shown is an infrared spectrum of an A5-perovskite solar cell, where the NH characteristic peak (1600 cm⁻¹) of S2 (blue curve) is visible. -1 The area near the target sample (red curve) shifts within the mixed sample, and the displacement is 900-1000 cm. -1 The characteristic peaks of P-OH in the range disappeared; combined with the weakening of the S2 skeletal vibration peak intensity, it can be determined that the NH and P-OH functional groups of S2 formed hydrogen bonds with the oxygen-containing groups of SAM. The hydrogen bonds weakened the chemical bond vibration characteristics of these functional groups, resulting in changes in their characteristic peaks.
[0058] To investigate the effect of introducing amino acids into SAM solution on perovskite solar cells, photoelectric tests were performed on the perovskite solar cells prepared in Examples 1-7 and Comparative Example 1. The test results are shown in [Figure 1]. Figure 6 and Figure 7 In the figure, voltage (in V) is plotted on the horizontal axis, and current density (in mA / cm²) is plotted on the vertical axis. 2 () is the ordinate.
[0059] For Example 1 Photoelectric testing was performed on the perovskite solar cells prepared in Comparative Example 7 and Comparative Example 1. The test temperature was 25 ± 1 ℃. The current density–voltage curves of the cells (J / s²) are shown below. V curves) are obtained from the source table (Keithley 2400) on the AM1.5G (100 mW / cm²) provided by the solar simulator (ABET Sun 3000). 2 Obtained under illumination, the battery area is 0.08 cm². 2 Before testing, the light intensity was calibrated using a standard silicon cell, and the scan rate was 10 mV / s.
[0060] Open-circuit voltage is the terminal voltage of the cell in the open-circuit state. Short-circuit current is the current density that the perovskite solar cell can generate under short-circuit conditions. Fill factor is the ratio of the maximum power of the solar cell to the product of the open-circuit voltage and the short-circuit current. Photovoltaic conversion efficiency is measured by measuring the current density-voltage curve (J / s). The V curves can be calculated. The test results are shown in Table 1. Figure 6-7 As shown.
[0061] Table 1 Photoelectric performance of perovskite solar cells
[0062] according to Figure 6 As shown, curve A represents A1-perovskite solar cells, curve B represents A7-perovskite solar cells, curve C represents A6-perovskite solar cells, and curve E represents B0-perovskite solar cells. (From Table 1 and...) Figure 6 The test results show that, for perovskite solar cells with different ratios, those based on the hole transport layer of the SAM-amino acid composite system (A1, A6, A7) generally outperform the pure SAM cell without amino acid modification (B0) in terms of photoelectric conversion performance. Furthermore, the different ratios of the composite system significantly affect the regulation of the cell's photoelectric performance. The appropriately ratiod composite system (A6) effectively optimizes the interfacial contact between the hole transport layer and the perovskite layer, as well as the degree of regulation of SAM by amino acids, allowing SAM to fully utilize its hole transport layer function. While the unsuitable composite system shows slightly better photoelectric performance parameters than the pure SAM-based cell (B0), it is significantly lower than A6, demonstrating that the ratio of SAM to amino acids has a crucial impact on the performance regulation of the composite hole transport layer.
[0063] according to Figure 7 As shown, curve SAM+LA represents A2-perovskite solar cells, curve SAM+L2 represents A3-perovskite solar cells, curve SAM+LN represents A4-perovskite solar cells, curve SAM+S2 represents A5-perovskite solar cells, and curve E represents B0-perovskite solar cells. (From Table 1 and...) Figure 7 The test results show that short-chain amino acids outperform long-chain amino acids in regulating the work function of the hole transport layer prepared by SAM solution. Different amino acid chain lengths modulate their dipole moments and electrostatic potentials, thus achieving regulation of the hole transport layer work function. The regulatory ability of short-chain amino acids allows for a more precise matching of the amino acid-SAM solution mixture to the valence band energy levels of the perovskite layer, significantly reducing the interfacial charge recombination resistance.
[0064] Battery stability performance test: The perovskite solar cells prepared using the examples and comparative examples were subjected to a heating aging test. First, the photoelectric performance of the B0-perovskite solar cells and A4-perovskite solar cells was tested at room temperature. Then, the two groups of materials were heated at 65 °C for one day in a nitrogen atmosphere. After that, they were taken out and the photoelectric performance was tested again. The test results are shown in Table 2.
[0065] Table 2 Test results of battery stability performance
[0066] Table 2 shows the stability test results. The initial room-temperature photoelectric conversion efficiency of the A4-perovskite solar cell is 25.65%, significantly higher than that of the B0-perovskite solar cell (22.83%), indicating that A4 has superior power generation performance at room temperature. In the heating stability test, the efficiency of the B0-perovskite solar cell decreased from 22.83% to 20.32% after heating, with a degradation of 2.5% and a degradation rate of 10.96%. The efficiency of the A4-perovskite solar cell decreased from 25.65% to 24.71% after heating, with a degradation of only 0.94% and a degradation rate of only 3.66%. This fully demonstrates that because amino acids can interact with SAM, they effectively passivate various defects on the perovskite surface and suppress carrier recombination at the interface. This not only improves the photoelectric conversion efficiency of the perovskite cell but also significantly enhances the thermal stability of the material, giving it superior environmental adaptability and durability.
[0067] Therefore, the hole transport layer provided in this application is made by chemically bonding a self-assembled monolayer with amino acids; it not only improves the stability of the SAM solution and enhances the transport efficiency of the hole transport layer, but also reduces surface defects in the perovskite layer and promotes charge transfer, thereby significantly improving the photoelectric conversion efficiency and stability of the perovskite solar cell.
[0068] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.
[0069] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.
Claims
1. A hole transport layer, characterized in that, The hole transport layer is formed by self-assembled monolayers containing oxygen-containing functional groups and covalently bonded amino and / or carboxyl groups of amino acids.
2. The hole transport layer according to claim 1, characterized in that, The self-assembled monolayer includes one or more of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid, (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid, [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid, and (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid.
3. The hole transport layer according to claim 1, characterized in that, The amino acids include one or more of L-2-aminohexanoic acid, L-alanine, L-2-aminobutyric acid, L-valine, and (S)-2-aminooctanoic acid.
4. The hole transport layer according to claim 1, characterized in that, The molar ratio of the self-assembled monolayer to the amino acid is (9-6):(1-4).
5. A perovskite solar cell, characterized in that, It includes a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode as described in any one of claims 1-4.
6. The perovskite solar cell according to claim 5, characterized in that, The perovskite layer is an organic-inorganic hybrid perovskite with the general formula ABX3; Where: A is methylamine ion, formamidinium ion, or cesium ion; B is either lead ion or tin ion; X is an iodide ion, bromide ion, or chloride ion; The electron transport layer comprises one or more of tin oxide, titanium oxide, or zinc oxide; The electrode comprises one or more of silver, copper, gold, and carbon.
7. A method for preparing a perovskite solar cell according to any one of claims 5-6, characterized in that, The method includes: After depositing a hole transport layer on the substrate; A perovskite layer is deposited on the hole transport layer and then passivated. An electron transport layer is deposited on the perovskite layer; Electrodes are deposited on the electron transport layer.
8. The method for preparing a perovskite solar cell according to claim 7, characterized in that, After depositing a hole transport layer on the substrate, the process includes: A self-assembled monolayer solution is mixed with an amino acid solution, and the resulting mixed solution is deposited on the substrate surface and annealed to form the hole transport layer.
9. The method for preparing a perovskite solar cell according to claim 8, characterized in that, The concentration of the self-assembled monolayer solution is 0.5-1 mg / mL; The concentration of the amino acid solution is 0.5-1 mg / mL.
10. The method for preparing a perovskite solar cell according to claim 8, characterized in that, The deposition method includes one of magnetron sputtering, thermal evaporation, electron beam evaporation, screen printing, blade coating, slot coating, or spraying.