Hybrid self-assembly hole transport layer and preparation method and application thereof
By mixing self-assembled molecules Me-4PACz with 2PACz, MeO-2PACz, or 4PADCB to form a self-assembled hole transport layer, the problems of coverage and energy level matching of a single molecular layer are solved, thereby improving the photoelectric conversion efficiency and stability of perovskite-silicon tandem solar cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF ELECTRONICS SCI & TECH OF CHINA
- Filing Date
- 2026-03-12
- Publication Date
- 2026-04-24
AI Technical Summary
Single-component self-assembled hole transport layers in perovskite-silicon tandem solar cells suffer from poor coverage, energy level mismatch, and poor wettability to perovskite solutions, which limits the improvement of cell performance.
Two self-assembled molecules, Me-4PACz and 2PACz, MeO-2PACz or 4PADCB, were mixed, dissolved in anhydrous ethanol at a specific mass ratio, spin-coated and annealed to form a hybrid self-assembled hole transport layer, which improved coverage and energy level matching and promoted the uniform spreading of the perovskite precursor solution.
It significantly improves the coverage and density of the hole transport layer, enhances hole extraction and transport capabilities, reduces the interface defect state density, and improves the photoelectric performance and stability of perovskite-silicon tandem solar cells.
Smart Images
Figure CN121925017A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photovoltaic cell technology, specifically providing a hybrid self-assembled hole transport layer and its preparation method, and a perovskite-silicon tandem solar cell. Background Technology
[0002] With the continuous development of photovoltaic technology, perovskite-silicon tandem solar cells, as a highly efficient photoelectric conversion device, have attracted much attention because they can break through the Shockley-Quyther theoretical limit of single-junction solar cells. In this tandem cell structure, the top perovskite cell and the bottom crystalline silicon cell work together to make more effective use of the solar spectrum, thereby obtaining higher photoelectric conversion efficiency.
[0003] In perovskite solar cells, the hole transport layer is one of the most crucial functional layers. It is responsible for extracting and transporting holes generated in the perovskite absorber layer, while simultaneously blocking electrons to reduce charge recombination. It also influences the deposition of the perovskite absorber layer. Therefore, an excellent hole transport layer has a decisive impact on improving the open-circuit voltage, fill factor, and ultimately, the photoelectric conversion efficiency of the cell. Self-assembled molecules, as an emerging hole transport layer material, have been extensively studied in recent years due to their ability to form dense, ordered monolayers, achieving strong bonding with the substrate (ITO) and excellent energy level matching. Among them, carbazole-phosphonic acid-based self-assembled molecules have proven to be effective hole transport materials. However, single-component self-assembled hole transport layers still have certain limitations in performance. For example, the film coverage, uniformity, and interfacial contact characteristics may not be ideal, which may lead to high charge transport resistance or the existence of interfacial recombination channels, thus limiting further improvements in cell performance.
[0004] Therefore, by mixing self-assembled molecules with different structures and utilizing their synergistic effect, it is expected to obtain a composite hole transport layer with better coverage, better energy level matching, and stronger charge extraction capability, which provides a new technical path for the fabrication of high-performance tandem solar cells. Summary of the Invention
[0005] The purpose of this invention is to provide a hybrid self-assembled hole transport layer, its preparation method, and its application, to solve the problems of poor coverage, energy level mismatch, and poor wettability of single-molecule self-assembled hole transport layers on silicon heterojunction substrates. This invention constructs a hybrid self-assembled hole transport layer through the combination and optimization of specific self-assembled molecules, significantly improving the coverage of the hole transport layer on the silicon heterojunction substrate and its wettability to the perovskite precursor solution. This achieves better energy level matching with the perovskite absorber layer, thereby effectively improving the photoelectric performance and stability of the battery.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A hybrid self-assembled hole transport layer is characterized by comprising two self-assembled molecules, the first being [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), and the second being [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), or (4-(7H-dibenzocarbazole-7-yl)butyl)phosphonic acid (4PADCB).
[0008] Furthermore, the mass ratio of the first self-assembled molecule to the second self-assembled molecule is 9:1 to 7:3.
[0009] Furthermore, the method for preparing the hybrid self-assembled hole transport layer includes the following steps:
[0010] The first type of self-assembled molecule and the second type of self-assembled molecule were dissolved in anhydrous ethanol at a predetermined mass ratio, and stirred at room temperature to ensure complete dissolution and mixing, thus obtaining a mixed self-assembled molecule solution.
[0011] A mixed self-assembled molecular solution was spin-coated onto the surface of an ITO substrate for a silicon heterojunction battery to form a monolayer liquid film.
[0012] The substrate that forms a monolayer liquid film is annealed at 100-200 °C for 10-20 min to form a hybrid self-assembled hole transport layer.
[0013] Furthermore, the total concentration of the mixed self-assembled molecular solution was 0.5-2 mg / mL.
[0014] Furthermore, the spin coating process parameters are: rotation speed of 2000-5000 rpm and time of 30-40 s.
[0015] An application of a hybrid self-assembled hole transport layer, wherein the perovskite-silicon tandem solar cell comprises: a silicon heterojunction base cell, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a buffer layer, a transparent electrode layer, a metal electrode layer, and an anti-reflection layer, characterized in that the hole transport layer is the hybrid self-assembled hole transport layer.
[0016] Furthermore, the thickness of the hybrid self-assembled hole transport layer is 3-10 nm.
[0017] Furthermore, the composition of the perovskite light-absorbing layer is FA. 0.80 MA 0.15 CS 0.05 Pb(Br 0.23 I0.77 )3, with a thickness of 500-700 nm.
[0018] Based on the above technical solution, the present invention has the following advantages compared with the prior art:
[0019] 1. This invention effectively improves the problem of insufficient wettability of a single Me-4PACz hole transport layer to perovskite precursor solutions by mixing Me-4PACz with a second type of self-assembled molecule (2PACz, MeO-2PACz, or 4PADCB) with a specific structure. The mixed molecular layer provides a more uniform surface energy distribution, promotes the uniform spreading of the perovskite precursor solution on the silicon heterojunction substrate, and thus helps to form a dense, pore-free, high-crystal-quality, and fully covered perovskite film, significantly improving film quality and device performance.
[0020] 2. This invention utilizes the complementary characteristics of different self-assembly molecules in terms of structural size and functional groups to achieve synergistic self-assembly between molecules. This hybrid system can effectively fill the gaps and defects formed by a single component during film formation, significantly improve the coverage and density of the hole transport layer, reduce the interface defect state density, enhance hole extraction and transport capabilities, and suppress non-radiative recombination.
[0021] 3. Based on the above structural advantages, the fabricated perovskite-silicon tandem solar cells achieve a comprehensive improvement in photoelectric performance, specifically manifested in a higher open-circuit voltage (V0). OC It features a higher fill factor (FF) and significantly improved photoelectric conversion efficiency (PCE); at the same time, the hybrid hole transport layer effectively improves the interface stability of the device, enabling it to exhibit excellent performance retention during long-term operation. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the molecular structures of the first and second self-assembled molecules in the hybrid self-assembled hole transport layer provided by the present invention.
[0023] Figure 2 This is a schematic diagram of the structure of the perovskite-silicon tandem solar cell provided by the present invention.
[0024] Figure 3 This is a comparison image of the hole transport layer in Embodiment 1 and Comparative Example 1 under Kelvin probe force microscopy (KPFM).
[0025] Figure 4 This is a comparison image of the perovskite thin film in Example 1 and Comparative Example 1 of the present invention under an atomic force microscope (AFM).
[0026] Figure 5This is a comparison image of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1 of the present invention, taken using a scanning electron microscope (SEM).
[0027] Figure 6 This is a comparison image of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1 of the present invention under atomic force microscopy (AFM).
[0028] Figure 7 This is a comparison image of the photoluminescence (PLmapping) of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1 of the present invention.
[0029] Figure 8 This is a comparison chart of the JV curves of the perovskite-silicon tandem solar cells in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation
[0030] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. There are no special restrictions on the source of all raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0031] This invention provides a hybrid self-assembled hole transport layer composed of two self-assembled molecules. Through the design of the hybrid system, it effectively fills the gaps and defects formed by the single component during the film formation process, significantly improves the coverage and compactness of the hole transport layer, reduces the interface defect state density, enhances hole extraction and transport capabilities, and suppresses non-radiative recombination.
[0032] Specifically, such as Figure 1 As shown, the first self-assembled molecule is [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), and the second self-assembled molecule is selected from at least one of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), or (4-(7H-dibenzocarbazole-7-yl)butyl)phosphonic acid (4PADCB); the mass ratio of the first self-assembled molecule to the second self-assembled molecule is 9:1-7:3.
[0033] Meanwhile, the present invention provides a method for preparing the above-mentioned hybrid self-assembled hole transport layer. The hybrid self-assembled hole transport layer obtained by this method can provide a more uniform surface energy distribution, promote the uniform spreading of the perovskite precursor solution on the silicon heterojunction substrate, thereby helping to form a dense, pore-free, high-crystal-quality, and fully covered perovskite film, significantly improving film quality and device performance; specifically including the following steps:
[0034] Solution preparation: Weigh the two self-assembled molecules and dissolve them in anhydrous ethanol according to the mass ratio to prepare a mixed self-assembled molecule solution with a total concentration of 0.5-2 mg / mL. Stir at room temperature to ensure complete dissolution and mixing.
[0035] Substrate treatment and spin coating: The silicon heterojunction base cell substrate with ITO was treated with ultraviolet ozone for 15 min to enhance hydrophilicity. Then, the above mixed solution was spin-coated onto the treated substrate surface at a speed of 2000-5000 rpm for 30-40 seconds to form a liquid film of 3-10 nm.
[0036] Annealing film formation: The spin-coated substrate is immediately placed on a hot stage and annealed at 100-200 °C for 10-20 min. After cooling, a 3-10 nm hybrid self-assembled hole transport layer is obtained.
[0037] Furthermore, the present invention also provides the application of the above-mentioned hybrid self-assembled hole transport layer in a perovskite-silicon tandem solar cell, wherein the perovskite-silicon tandem solar cell is as follows: Figure 2 As shown, it includes: a silicon heterojunction base cell, a hole transport layer, and a perovskite light-absorbing layer (FA). 0.80 MA 0.15 CS 0.05 Pb(Br 0.23 I 0.77 3) Electron transport layer (LiF and C) 60 The perovskite absorber layer consists of a SnO2 buffer layer, a transparent electrode layer (indium zinc oxide IZO), a metal electrode layer (Ag), and an anti-reflection layer (LiF or MgF2). The hole transport layer is a hybrid self-assembled hole transport layer. Furthermore, to achieve good current matching between the perovskite absorber layer and the silicon heterojunction base cell, the perovskite absorber layer is composed of FA. 0.80 MA 0.15 CS 0.05 Pb(Br 0.23 I 0.77 )3, the band gap of the perovskite light-absorbing layer film prepared by it is 1.68eV.
[0038] Example 1
[0039] This embodiment provides a hybrid self-assembled hole transport layer, which is composed of two self-assembled molecules. The first self-assembled molecule is Me-4PACz, and the second self-assembled molecule is 4PADCB. The mass ratio of Me-4PACz to 4PADCB is 8:2.
[0040] The hybrid self-assembled hole transport layer is prepared by the following steps:
[0041] Solution preparation: Weigh Me-4PACz and 4PADCB, dissolve them in anhydrous ethanol at a mass ratio of 8:2 to prepare a mixed self-assembled molecular solution with a total concentration of 1 mg / mL, and stir at room temperature to ensure complete dissolution and mixing;
[0042] Substrate treatment and spin coating: The silicon heterojunction base cell substrate with ITO was treated with ultraviolet ozone for 15 min to enhance hydrophilicity. Then, the above mixed solution was spin-coated onto the treated substrate surface at 3000 rpm (30 seconds) to form a liquid film.
[0043] Annealing film formation: The spin-coated substrate was immediately placed on a hot stage and annealed at 100 °C for 10 minutes. After cooling, a Me-4PACz:4PADCB hybrid self-assembled hole transport layer with a thickness of 3-10 nm was obtained.
[0044] Based on the above-mentioned hybrid self-assembled hole transport layer, this embodiment also fabricates a perovskite-silicon tandem solar cell, specifically including the following steps:
[0045] Step 1: Cut the silicon wafer into 2×2 cm pieces 2 The silicon heterojunction bottom cell 1 has a silicon wafer with a center area of 1.2 × 1.2 cm. 2 The substrate composite layer is controlled to have a cutting accuracy error within 1 mm. The cut silicon wafers are annealed at 200℃ for 15 min for later use. The thickness of the silicon heterojunction bottom cell 1 is 150 µm, and the thickness of the substrate composite layer ITO is 10 nm.
[0046] Step 2: Preparation of the hybrid self-assembled hole transport layer;
[0047] Step 3: The preparation process of the perovskite light-absorbing layer is as follows: FA 0.80 MA 0.15 CS 0.05 Pb(Br 0.23 I 0.77 )3 was mixed with N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to obtain a perovskite precursor solution. The perovskite precursor solution was spin-coated onto the upper surface of the mixed self-assembled hole transport layer and annealed on a hot stage at 100 °C for 20 min to obtain a perovskite light-absorbing layer film with a thickness of about 600 nm.
[0048] Step 4: In the vacuum evaporation coating system, at 1×10 -4 LiF and C were sequentially deposited under a vacuum of Pa. 60 The deposition rates were 0.1 Å / s and 0.3 Å / s, respectively, and the thicknesses were 1 nm and 10 nm, respectively, to obtain a stacked structure of silicon heterojunction bottom cell / hole transport layer / perovskite light-absorbing layer / electron transport layer.
[0049] Step 5: Place the stacked structure obtained in Step 4 into the cavity of the atomic layer deposition system to deposit tin dioxide and prepare a buffer layer. The vacuum degree is 20 Pa, the cavity temperature is 100℃, the number of deposition cycles is set to 200, and the deposition thickness is 15 nm to obtain the stacked structure of silicon heterojunction bottom cell / hole transport layer / perovskite absorber layer / electron transport layer / buffer layer.
[0050] Step 6: Place the stacked structure obtained in Step 5 in a mask of a transparent conductive electrode, and then place the mask in a magnetron sputtering process with a vacuum degree of 9.9 × 10⁻⁶. -4 At Pa, IZO was prepared to obtain a transparent conductive electrode. The sputtering mode was DC sputtering, the substrate temperature was 25℃, the argon flow rate was 20 sccm, the oxygen flow rate was 0.3 sccm, the sputtering intensity was 200 W, the sputtering time was 210 s, and the sputtering thickness was 55 nm, resulting in a stacked structure of silicon heterojunction bottom cell / hole transport layer / perovskite absorber layer / electron transport layer / buffer layer / transparent conductive electrode.
[0051] Step 7: Place the stacked structure obtained in Step 6 into the mask of the positive electrode 7, and then place the mask into a vacuum deposition apparatus to prepare the metal electrode at a vacuum level of 7 × 10⁻⁶. -4 Pa, with a positive electrode thickness of 600 nm;
[0052] Step 8: After completing the fabrication of the metal electrodes, place the stacked structure in a 1.1×1.1cm space. 2 On the mask, the mask is then placed in a vacuum deposition apparatus to prepare the antireflection layer, with a vacuum level of 9.9 × 10⁻⁶. -4 Pa, with a thickness of 100 nm, yielded the final perovskite / silicon tandem solar cell.
[0053] Example 2
[0054] This embodiment provides a hybrid self-assembled hole transport layer, which is composed of two self-assembled molecules. The first self-assembled molecule is Me-4PACz, and the second self-assembled molecule is 2PACz. The mass ratio of Me-4PACz to 2PACz is 8:2. Other steps and structures are the same as in Embodiment 1.
[0055] Example 3
[0056] This embodiment provides a hybrid self-assembled hole transport layer, which is composed of two self-assembled molecules. The first self-assembled molecule is Me-4PACz, and the second self-assembled molecule is MeO-2PACz. The mass ratio of Me-4PACz to MeO-2PACz is 8:2. Other steps and structures are the same as in Example 1.
[0057] Example 4
[0058] This embodiment provides a hybrid self-assembled hole transport layer, which is composed of two self-assembled molecules. The first self-assembled molecule is Me-4PACz, and the second self-assembled molecule is 4PADCB. The mass ratio of Me-4PACz to 4PADCB is 9:1. Other steps and structures are the same as in Example 1.
[0059] Example 5
[0060] This embodiment provides a hybrid self-assembled hole transport layer, which is composed of two self-assembled molecules. The first self-assembled molecule is Me-4PACz, and the second self-assembled molecule is 4PADCB. The mass ratio of Me-4PACz to 4PADCB is 7:3. Other steps and structures are the same as in Example 1.
[0061] The beneficial effects of the present invention will be explained in detail below with reference to simulation tests.
[0062] To more intuitively illustrate the beneficial effects of the present invention, the present invention also provides Comparative Example 1: a perovskite silicon tandem solar cell, which differs from Example 1 in that: the hole transport layer uses a single self-assembled molecule Me-4PACz, and the solution concentration during the preparation of the hole transport layer is 1 mg / mL.
[0063] like Figure 3 The images shown are of the hole transport layer in Example 1 and Comparative Example 1 under Kelvin probe force microscopy (KPFM). Figure 4 The images shown are of the perovskite films in Example 1 and Comparative Example 1 under an atomic force microscope (AFM). Figure 3 and Figure 4 The surface morphology and roughness of the thin film were characterized. As can be seen from the figure, the RMS of Example 1 was 3.74 nm, while that of Comparative Example 1 was 8.72 nm. This indicates that the hole transport layer of the present invention has a smoother and more uniform surface with lower roughness. A lower RMS value usually means fewer surface defects and better interfacial contact, thereby reducing carrier recombination and improving battery performance. In Comparative Example 1, the higher roughness may be due to the poor film-forming properties of the single hole transport layer, resulting in uneven perovskite crystallization.
[0064] like Figure 5The images shown are scanning electron microscope (SEM) images of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1, used to display the microstructure at the buried interface of the perovskite thin film. As can be seen from the figures, Example 1 shows a denser, more continuous perovskite layer, forming good interfacial contact with the hybrid self-assembled hole transport layer, which is beneficial for charge separation and transport. In contrast, Comparative Example 1 shows porosity or uneven coverage at the interface, leading to increased interfacial recombination. This verifies that the hybrid self-assembled hole transport layer provided by the present invention can promote uniform perovskite film formation. Furthermore, as... Figure 6 The images shown are atomic force microscopy (AFM) images of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1, used to quantify the roughness of the buried interface. As can be seen from the figures, Example 1 is expected to show a smoother interface, while Comparative Example 1 has a higher interface roughness. A smooth interface can reduce interface defect states, improve carrier transport, and thus increase open-circuit voltage and fill factor; this is consistent with... Figure 4 The surface AFM results shown are consistent, highlighting the positive impact of the hybrid self-assembled hole transport layer on interface engineering.
[0065] like Figure 7 The figures show photoluminescence (PL) images of the buried interface of the perovskite film in Example 1 and Comparative Example 1, used to reflect the uniformity and defect density at the buried interface of the perovskite film. As can be seen from the figures, Example 1 shows a more uniform and stronger PL signal, indicating a lower defect density, which is attributed to the good interface provided by the hybrid self-assembled hole transport layer. In contrast, Comparative Example 1 may show an uneven PL signal, indicating the presence of more non-radiative recombination centers.
[0066] like Figure 8 The figure shows the JV curves of the perovskite-silicon tandem solar cells in Example 1 and Comparative Example 1. As can be seen from the figure, the photoelectric conversion efficiency, fill factor and open circuit voltage of the cell using the hybrid self-assembled hole transport layer provided by the present invention are significantly higher than those of Comparative Example 1.
[0067] In summary, this invention effectively addresses the shortcomings of a single molecular layer in terms of coverage, energy level matching, and wettability by mixing specific self-assembled molecules, providing a reliable interface engineering solution for the fabrication of high-efficiency and high-stability perovskite-silicon tandem solar cells.
[0068] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.
Claims
1. A hybrid self-assembled hole transport layer, characterized in that, It consists of two self-assembled molecules. The first self-assembled molecule is [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), and the second self-assembled molecule is [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), or (4-(7H-dibenzocarbazole-7-yl)butyl)phosphonic acid (4PADCB).
2. The hybrid self-assembled hole transport layer according to claim 1, characterized in that, The mass ratio of the first type of self-assembled molecule to the second type of self-assembled molecule is 9:1 to 7:
3.
3. The method for preparing the hybrid self-assembled hole transport layer according to claim 1, characterized in that, Includes the following steps: The first type of self-assembled molecule and the second type of self-assembled molecule were dissolved in anhydrous ethanol at a predetermined mass ratio, and stirred at room temperature to ensure complete dissolution and mixing, thus obtaining a mixed self-assembled molecule solution. A mixed self-assembled molecular solution was spin-coated onto the surface of an ITO substrate for a silicon heterojunction battery to form a monolayer liquid film. The substrate that forms a monolayer liquid film is annealed at 100-200 °C for 10-20 min to form a hybrid self-assembled hole transport layer.
4. The method for preparing the hybrid self-assembled hole transport layer according to claim 3, characterized in that, The total concentration of the mixed self-assembled molecular solution was 0.5-2 mg / mL.
5. The method for preparing the hybrid self-assembled hole transport layer according to claim 3, characterized in that, Spin coating process parameters: rotation speed 2000-5000 rpm, time 30-40 s.
6. The application of a hybrid self-assembled hole transport layer in a perovskite-silicon tandem solar cell, characterized in that, The perovskite-silicon tandem solar cell comprises: a silicon heterojunction base cell, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a buffer layer, a transparent electrode layer, a metal electrode layer, and an anti-reflection layer, wherein the hole transport layer is the hybrid self-assembled hole transport layer as described in claim 1.
7. The application of the hybrid self-assembled hole transport layer according to claim 6 in perovskite-silicon tandem solar cells, characterized in that, The thickness of the hybrid self-assembled hole transport layer is 3-10 nm.
8. The application of the hybrid self-assembled hole transport layer according to claim 6 in perovskite-silicon tandem solar cells, characterized in that, The perovskite light-absorbing layer is composed of FA. 0.80 MA 0.15 Cs 0.05 Pb(Br 0.23 I 0.77 )3, with a thickness of 500-700 nm.