Dibenzocarbazole alkyl phosphonic acid dimer additive applied to trans-perovskite solar cell

Abstract

The invention belongs to the field of organic photoelectric materials, and discloses a dibenzocarbazole alkyl phosphonic acid dimer additive applied to a trans-perovskite solar cell, the dibenzocarbazole alkyl phosphonic acid dimer compound takes dibenzocarbazole as a molecular skeleton, and two dibenzocarbazole derivative units are connected through a C-C single bond, so that the dibenzocarbazole alkyl phosphonic acid dimer additive is obtained. The connection sites of the C-C single bond are respectively located at the 2-position and the 11-position of the two dibenzocarbazole units, and each dibenzocarbazole derived unit has a phosphonic acid group connected through an alkyl chain. The obtained dibenzocarbazole alkyl phosphonic acid dimer compound can be particularly used as an additive to be applied to a trans-perovskite solar cell, interface interaction can be improved and enhanced, and high energy conversion efficiency of a device is achieved. In addition, the perovskite light absorption layer can be prepared by a one-step method, a hole transport layer does not need to be prepared independently, and the preparation process of the device is further simplified.

Description

Technical Field

[0001] The present invention belongs to the field of organic photoelectric materials, and more specifically, relates to a dibenzocarbazolidine phosphonic acid dimer additive used in inverse perovskite solar cells. Background Art

[0002] Perovskite solar cells have attracted widespread attention in recent years due to their high photoelectric conversion efficiency, low cost, and simple processing. Perovskite solar cells can be divided into formal and trans structures according to the order of p, i, and n. The formal device adopts the nip structure, while the trans structure adopts the pin structure. The traditional perovskite solar cell structure generally includes functional layers such as the electron transport layer, perovskite light absorption layer, hole transport layer, and electrode (taking the trans structure as an example, the traditional perovskite solar cell includes, from top to bottom, the electrode, electron transport layer, perovskite light absorption layer, hole transport layer, and transparent conductive substrate). The hole transport layer (HTL) is often prepared by separate solution processing or evaporation methods. Common materials include Spiro-OMeTAD, PTAA, and PEDOT:PSS. However, these HTL materials have problems such as high cost, poor stability, and complex processing, which have hindered the further commercial development of perovskite solar cells.

[0003] In recent years, studies have proposed the introduction of self-assembled monolayers (SAMs) as hole transport materials to reduce interfacial energy losses. SAM molecules usually have specific functional groups that can undergo directional adsorption or chemical bonding with the perovskite surface, regulate the arrangement of interfacial energy levels, enhance carrier selectivity, and inhibit non-radiative recombination. In addition, the introduction of SAMs can also help improve the interface stability and environmental adaptability of devices. However, existing SAM materials are mostly used as independent interface modification layers or hole transport layers, which require separate spin coating (that is, a SAM layer is independently spin-coated as an interface modification layer between the hole transport layer and the perovskite layer, or a SAM layer is independently spin-coated directly as a hole transport layer), resulting in a complex process flow and increased preparation costs.

[0004] In order to simplify the device structure and reduce the difficulty of preparation, some studies have attempted to use SAM as an additive to co-deposit with perovskite precursors, thereby simplifying the process and improving the quality of perovskite crystals. However, the SAM materials currently available for one-step co-deposition are mainly represented by 4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz). This molecule has limited interaction with the substrate and perovskite, and is prone to agglomeration, affecting the perovskite film formation process and the final device performance. Therefore, if a new type of SAM molecule suitable for one-step co-deposition can be developed, it can not only enhance its interaction with the perovskite and the substrate, but also effectively inhibit molecular aggregation, achieving simultaneous optimization of interface regulation and perovskite crystallization, which is undoubtedly a key innovation direction for improving the performance and stability of perovskite devices and promoting process simplification. Summary of the Invention

[0005] In view of the problems of insufficient interfacial bonding force and film defects caused by molecular aggregation in the hole-selective interface modification and perovskite film quality improvement of the prior art in trans perovskite solar cells, the present invention aims to provide a dibenzocarbazole alkylphosphonic acid dimer additive for use in trans perovskite solar cells. By improving the chemical structure of the material (using dibenzocarbazole as the molecular skeleton, two carbazole compounds are connected by a C-C single bond, and each dibenzocarbazole structural unit is connected to a phosphonic acid group via an alkyl chain), the obtained dibenzocarbazole alkylphosphonic acid dimer compound can be used as an additive in trans perovskite solar cells, which can enhance and strengthen the interfacial interaction and achieve high energy conversion efficiency of the device. In addition, when the dibenzocarbazole alkylphosphonic acid dimer is used as a perovskite SAM additive, it can also realize a one-step preparation of the perovskite light absorption layer, without the need for a separate preparation of the hole transport layer, further simplifying the device preparation process.

[0006] To achieve the above objectives, according to one aspect of the present invention, a dibenzocarbazole alkylphosphonic acid dimer compound is provided, characterized in that the compound uses dibenzocarbazole as a molecular skeleton, and two dibenzocarbazole derivative units are connected by a C-C single bond, the connection sites of the C-C single bond are respectively located at the 2nd and 11th positions of the two dibenzocarbazole units, and each dibenzocarbazole derivative unit has a phosphonic acid group connected by an alkyl chain.

[0007] As a further preferred embodiment of the present invention, its structure is shown in general formula (A):

[0008]

[0009] Wherein, n is an integer of 1-5; the substituent R is selected from hydrogen atom, methyl, ethyl, methoxy, fluorine and chlorine, and the substitution sites are positions 4 and 9 of the dibenzocarbazole unit.

[0010] According to another aspect of the present invention, the present invention provides the use of the above-mentioned dibenzocarbazolidine phosphonic acid dimer compound in an inverse perovskite solar cell.

[0011] As a further preferred embodiment of the present invention, the dibenzocarbazolidine phosphonic acid dimer compound is added as an additive to the perovskite light absorbing layer.

[0012] As a further preferred embodiment of the present invention, the perovskite light absorbing layer is prepared by adding the dibenzocarbazole alkylphosphonic acid dimer compound to a perovskite precursor solution, blending the mixture, and then co-depositing the mixture to form a perovskite light absorbing layer containing the dibenzocarbazole alkylphosphonic acid dimer compound.

[0013] As a further preference of the present invention, the inverse perovskite solar cell does not require a separate hole transport layer.

[0014] As a further preferred embodiment of the present invention, the perovskite light absorption layer is formed by adding the dibenzocarbazole alkylphosphonic acid dimer compound to the perovskite precursor solution, and then spin-coating it on a transparent conductive substrate, thereby forming a perovskite light absorption layer added with the dibenzocarbazole alkylphosphonic acid dimer compound on the transparent conductive substrate.

[0015] The above technical solution conceived by the present invention, compared with the prior art, demonstrates that the dibenzocarbazole-based dibenzoylphosphonic acid dimer of the present invention uses dibenzocarbazole as the backbone, with C–C single bonds linking the units to form a twisted dibenzocarbazole-based dibenzoylphosphonic acid dimer structure. The positions of the dibenzocarbazole units are shown below. The dibenzocarbazole-based dibenzoylphosphonic acid dimer of the present invention is linked by a C–C single bond at position 2 of one dibenzocarbazole unit to position 11 of another dibenzocarbazole unit.

[0016]

[0017] The dibenzocarbazole alkylphosphonic acid dimer compound of the present invention may particularly have a structure represented by general formula (A):

[0018]

[0019] On the one hand, the above structure enhances the interaction force between the molecules and the perovskite interface, improving the effectiveness of interface modification. On the other hand, it effectively inhibits excessive aggregation between molecules through the intramolecular twisted structure, which helps to obtain high-quality perovskite films and optimize the interface charge transfer characteristics.

[0020] The dibenzocarbazole alkylphosphonic acid dimer obtained by the present invention can be used as an additive for trans-perovskite solar cells. The twisted conformation of the material itself can inhibit the aggregation of molecules in the perovskite precursor solution. On the other hand, the multi-anchor group can enhance the interaction with the transparent conductive substrate (such as ITO) and the perovskite, promote the hole extraction and transmission of the perovskite to form a high-quality crystal film and the interface, thereby obtaining a high-performance device. The dibenzocarbazole alkylphosphonic acid dimer can interact with the transparent conductive substrate (such as ITO) and the perovskite through the multi-anchor enhancement compound, while forming a twisted conformation, increasing the molecular steric hindrance, inhibiting the aggregation of molecules in the perovskite precursor solution, and improving the battery efficiency. The dibenzocarbazole alkylphosphonic acid dimer obtained by the present invention can be introduced as an additive into the trans-planar structure perovskite solar cell, without the need to prepare a hole transport layer in advance. Taking the following examples as an example, a high photoelectric conversion efficiency of 26.83% can be achieved (this PCE is one of the highest efficiencies of the current device with this structure), significantly improving the photoelectric conversion efficiency of the trans-perovskite solar cell, showing a very high application prospect.

[0021] Commonly used self-assembled monolayer (SAM) materials are prone to molecular aggregation during application. Existing strategies to inhibit aggregation primarily involve the co-deposition of other small molecules to form smaller molecular clusters, thereby reducing the aggregation tendency of SAM molecules. However, these methods primarily rely on non-covalent interactions between molecules, which are weak and susceptible to external conditions such as solvent, concentration, and temperature, making them unsuitable for one-step co-deposition processes. Existing dimeric SAM materials often use carbazole as their core structure and primarily utilize a 3- and 6-position linkage. This structure positions the phosphate groups on either side of the molecule, resulting in a planar and stretched molecule that is prone to stacking and aggregation, hindering uniform interface modification and improving device performance. This innovative method connects two dibenzocarbazole units at the 2- and 11-positions via a carbon-carbon single bond. Using molecular design, it introduces steric hindrance, allowing the dimer to spontaneously form a highly distorted spatial structure, significantly suppressing self-aggregation. Unlike traditional non-covalent regulation, this strategy intrinsically modulates the aggregation properties of molecules through chemical bonds, resulting in a strong effect and good environmental adaptability. Furthermore, the 2,11-position connection allows the two phosphonic acid groups to be located on the same side, significantly enhancing the multi-point anchoring and interfacial passivation capabilities of the molecule to transparent conductive substrates (e.g., ITO) and perovskite surfaces. It also facilitates the formation of intramolecular hydrogen bonds between the phosphonic acid groups, further stabilizing the distorted conformation. Ultimately, this molecular design effectively achieves multiple functions, including simultaneously inhibiting molecular aggregation, enhancing interfacial interactions, and promoting perovskite crystallization, providing new insights into interface engineering for one-step, high-performance perovskite devices.

[0022] Specifically, the dibenzocarbazole alkylphosphonic acid dimer obtained by the present invention can achieve the following beneficial effects:

[0023] (1) Significantly improve the photoelectric conversion efficiency: Using benzocarbazole alkylphosphonic acid dimer as an additive can significantly improve the photoelectric conversion efficiency of inverse perovskite solar cells, with the highest efficiency reaching 26.83%.

[0024] The dibenzocarbazole dimer in the present invention belongs to a SAM molecule, but is different from the SAM molecules reported in the prior art (such as Me-4PACz). The dibenzocarbazole alkylphosphonic acid dimer compound in the present invention is composed of two dibenzocarbazole alkylphosphonic acids connected by a C-C single bond to form a twisted dimer structure, and multiple anchoring groups can enhance the interaction between the molecule and the perovskite interface.

[0025] (2) Simplified device structure: The dibenzocarbazole alkylphosphonic acid dimer of the present invention can be used as an additive to achieve efficient carrier extraction and transport without separately preparing a hole transport layer, thereby simplifying the battery preparation process and reducing manufacturing costs.

[0026] The dibenzocarbazole alkylphosphonic acid dimer in the present invention can be directly blended with the perovskite precursor solution when used, without the need to prepare a hole transport layer separately. A transparent conductive substrate can be used as the substrate to achieve simultaneous integration of interface modification and film formation through a one-step co-deposition process.

[0027] (3) Possessing multiple anchoring points to enhance interfacial charge transfer: Dibenzocarbazole alkylphosphonic acid dimer belongs to SAM material, and its molecule contains multiple phosphonic acid anchoring groups, which can effectively enhance the anchoring effect between the SAM material and the transparent conductive substrate (such as ITO substrate), further improve the interfacial charge transfer efficiency, and reduce the interface resistance.

[0028] (4) Improve the quality of perovskite films: Dibenzocarbazole alkylphosphonic acid dimer enhances the interaction between SAM molecules and perovskite through molecular structure design, effectively passivates perovskite defects, and improves film quality.

[0029] (5) Improved dispersibility: The steric hindrance structure enables the molecule to have excellent dispersibility in the precursor solution and prevents the interfacial energy loss caused by SAM aggregation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the synthetic route of D4PA in Example 1.

[0031] Figure 2 This is the H NMR spectrum of compound 3 in Example 1.

[0032] Figure 3 This is the H NMR spectrum of compound 4 in Example 1.

[0033] Figure 4This is the H NMR spectrum of compound 5 in Example 1.

[0034] Figure 5 This is the H NMR spectrum of compound 6 in Example 1.

[0035] Figure 6 This is the H NMR spectrum of D4PA in Example 1.

[0036] Figure 7 This is the C NMR spectrum of D4PA in Example 1.

[0037] Figure 8 This is the high-resolution mass spectrum of D4PA in Example 1.

[0038] Figure 9 This is the theoretical simulation calculation of the interface interaction between D4PA and ITO in Example 2.

[0039] Figure 10 This is the XPS spectrum of D4PA and ITO film in Example 2.

[0040] Figure 11 This is the theoretical simulation calculation of the interface interaction between D4PA and perovskite in Example 3.

[0041] Figure 12 This is the XPS spectrum of D4PA and perovskite film in Example 3.

[0042] Figure 13 This is the DLS graph of D4PA in Example 4 in the perovskite precursor solution.

[0043] Figure 14 This is the optimal device JV curve of the trans-planar structure perovskite cell with D4PA and Me-4PACz as additives in Example 5. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0045] Example 1

[0046] The synthesis of compound D4PA, the synthesis route is as follows Figure 1 As shown, the following steps are included:

[0047] (1) Synthesis of Compound 2:

[0048] Compound 1 (2.7 g, 10 mmol) was dissolved in N,N-dimethylformamide (DMF, 50 mL) and cooled to -20°C. At room temperature, N-bromosuccinimide (NBS, 1.8 g, 10 mmol) was dissolved in DMF (30 mL) and added dropwise to the -20°C solution over 30 minutes. The reaction system was gradually warmed to room temperature and stirred overnight. After completion of the reaction, the mixture was extracted with dichloromethane, and the organic phase was separated and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure to obtain 3.2 g of a pale yellow crude product with a yield of 92.5%, which was used directly in the next reaction.

[0049] (2) Synthesis of compound 3:

[0050] Compound 2 (3.2 g, 0.93 mmol) was dissolved in 1,4-dibromobutane (10 mL), and tetrabutylammonium bromide (0.32 g, 0.1 mmol) and 50% aqueous potassium hydroxide solution (1.1 mL, 20 mmol) were added. The mixture was heated to 70°C and stirred overnight. After the reaction was completed, the product was extracted with dichloromethane, and the organic phase was separated and dried over anhydrous sodium sulfate. After removing the solvent under reduced pressure, the crude product was purified by silica gel column chromatography (petroleum ether: dichloromethane = 5:1, volume ratio, the same below) to obtain 3.8 g of a white crystalline solid with a yield of 85.0%.

[0051] The obtained product is compound 3, and the H NMR spectrum data are as follows: 1 H NMR (600 MHz, Chloroform-d) δ9.22 (d, J = 8.6 Hz, 1H), 9.14 (d, J = 8.4 Hz, 1H), 8.50 (dd, J = 8.4, 1.3 Hz, 1H), 8.07 (dd, J = 8.1, 1.3 Hz, 1H), 8.05 (s, 1H), 7.95 (d, J = 8.9 Hz, 1H), 7.75–7.63 (m, 4H), 7.57–7.54 (m, 1H), 4.52 (t, J = 7.2 Hz, 2H), 3.40 (t, J = 6.5 Hz, 2H), 2.15–2.13 (m, 2H), 1.97–1.92 (m, 2H). The H NMR spectrum of compound 3 is shown in FIG. Figure 2 shown.

[0052] (3) Synthesis of compound 4:

[0053] Compound 3 (2.8 g, 5.0 mmol), bis(methylenedioxy)diboron (2.5 g, 10 mmol), potassium acetate (2.0 g, 20 mmol), and Pd(dppf)Cl2 (0.16 g, 0.20 mmol) were added to 1,4-dioxane (20 mL) and heated under reflux for 24 hours under a nitrogen atmosphere. After the reaction was completed, it was cooled to room temperature and extracted with dichloromethane. The organic phase was collected, washed with water, and dried over anhydrous sodium sulfate. After rotary evaporation to remove the solvent, the crude product was purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1) to obtain white solid compound 4 in a yield of 1.60 g and a yield of 60.6%.

[0054] The H NMR spectrum data of the product compound 4 are as follows: 1 H NMR (400 MHz, Chloroform-d) δ9.19 (d, J = 8.4 Hz, 2H), 9.01 (d, J = 8.5 Hz, 1H), 8.33 (s, 1H), 8.04 (d, J = 8.0 Hz, 1H), 7.94 (d, J = 8.9 Hz, 1H), 7.72 (d, J = 8.8 Hz, 1H), 7.66 (q, J = 7.0 Hz, 2H), 7.54 (dt, J = 19.6, 7.6 Hz, 2H), 4.68 (t, J = 7.0 Hz, 2H), 3.40 (t, J = 6.5 Hz, 2H), 2.22–2.10 (m, 2H), 1.95 (d, J = 7.6 Hz, 2H), 1.49 (s, 12H). The H NMR spectrum of compound 4 is shown in FIG. Figure 3 shown.

[0055] (4) Synthesis of Compound 5:

[0056] Compound 3 (0.96 g, 2.0 mmol), compound 4 (1.1 g, 2.0 mmol), potassium carbonate (1.4 g, 10 mmol) and tetrakis(triphenylphosphine)palladium (92 mg, 0.08 mmol) were added to anhydrous tetrahydrofuran (20 mL) and degassed water (10 mL), heated to 75 ° C under a nitrogen atmosphere, and stirred for 24 hours. After the reaction was completed, it was cooled to room temperature and extracted with dichloromethane. The organic phase was collected, washed with water, and dried over anhydrous sodium sulfate. After rotary evaporation to remove the solvent, the crude product was purified by silica gel column chromatography (petroleum ether: dichloromethane = 2: 1) to obtain a light yellow solid compound 5 with a yield of 0.90 g and a yield of 56.3%.

[0057] The H NMR spectrum data of the product compound 5 are as follows: 1H NMR(600MHz,Chloroform-d)δ9.37(d,J=8.5Hz,2H),9.35(d,J=8.4Hz,2H),8.13( d,J=8.2Hz,2H),8.01(d,J=8.7Hz,2H),7.94(s,2H),7.81(d,J=8.8Hz,2H),7.79– 7.69(m,6H),7.59(ddd,J=7.9,6.8,1.0Hz,2H),7.36(ddd,J=8.1,6.7,1.1Hz,2H) ,4.66(t,J=7.1Hz,4H),3.54–3.37(m,4H),2.24–2.13(m,4H),1.99–1.89(m,4H). The H NMR spectrum of compound 5 is as follows Figure 4 shown.

[0058] (5) Synthesis of Compound 6:

[0059] Compound 5 (0.80 g, 1.0 mmol) was dissolved in triethylphosphine (10 mL, 52 mmol) and heated at 150°C overnight. After completion of the reaction, the solvent was removed under reduced pressure, and the crude product was purified by silica gel column chromatography (dichloromethane:ethyl acetate = 1:10) to obtain 0.82 g of the product as a yellow resin in a yield of 89.4%.

[0060] The obtained product is compound 6, and the H NMR spectrum data are as follows: 1 H NMR(400MHz,Chloroform-d)δ9.35–9.30(m,4H),8.10(dd,J=8.2,1.3Hz,2H),7.9 8(d,J=8.8Hz,2H),7.91(s,2H),7.78(d,J=8.9Hz,2H),7.76–7.65(m,6H),7.56(d dd,J=8.0,6.8,1.0Hz,2H),7.33(ddd,J=8.1,6.8,1.1Hz,2H),4.62(t,J=7.3Hz,4 H),4.02–3.88(m,8H),2.15–2.01(m,4H),1.74–1.68(m,8H),1.18–1.12(m,12H). The H NMR spectrum of compound 6 is as follows Figure 5 shown.

[0061] (6) Synthesis of compound D4PA:

[0062] Compound 6 (0.80 g, 0.87 mmol) was dissolved in anhydrous 1,4-dioxane (15 mL). Under an argon atmosphere, trimethylsilyl bromide (1.5 mL, 11 mmol) was added dropwise and stirred at 25°C for 24 hours. After the reaction, methanol (2 mL) was added and stirring continued for 3 hours. Distilled water (15 mL) was then added dropwise until the solution became turbid and stirring continued for 2 hours. The resulting product was filtered, washed with water, and recrystallized from dichloromethane to obtain 0.50 g of a yellow powder with a yield of 71.5%.

[0063] The H NMR and C NMR data of the product are as follows: 1 H NMR (600MHz, DMSO-d6) δ9.22(d,J=8.5Hz,2H),9.18(d,J=8.3Hz,2H),8.25(s,2H),8.17(d,J=8.1Hz,2H),8.11(d,J=8.9Hz,2H),8.05(d,J=8.8Hz,2H) ,7.77(t,J=7.6Hz,2H),7.71(t,J=7.6Hz,2H),7.65–7.49(m,4H),7.35(t, J=7.6Hz, 2H), 4.76 (t, J=7.4Hz, 4H), 2.02–1.96 (m, 4H), 1.74–1.48 (m, 8H). 13 C NMR (101MHz, DMSO) δ137.16,136.77,136.46,129.47,129.31,128.98,128.48,127.77,126.59,125.60,125.37 ,124.52,124.18,123.36,123.23,116.00,115.92,114.00,111.89,42.34,30.52,27.95,26.59,25.11,20.32. HRMS(APCI):(MH) - =803.2442(calcd for C 48 H 41 N2O6P2 - ,803.2445). The product is D4PA, with the following structural formula:

[0064]

[0065] The H NMR and C NMR spectra of the products are shown in Figure 2. Figure 6 and Figure 7 Its high-resolution mass spectrum is shown in Figure 8 shown.

[0066] The D4PA prepared in Example 1 belongs to a SAM molecule.

[0067] Example 2

[0068] This example discusses the interface anchoring between D4PA and ITO:

[0069] We first employed density functional theory (DFT) calculations to systematically investigate the interactions between D4PA molecules and the ITO substrate (using indium oxide as a model) and perovskite (using FAPbI3 as a reference). First-principles density functional theory (DFT) calculations were performed using the Vienna Ab initioSimulation Package (VASP 6.4) to systematically investigate the geometric and electronic structures of bare ITO and self-assembled monolayer (SAM)-modified ITO surfaces. Unless otherwise specified, the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation was used for electron exchange-correlation functionals. Given the presence of heavy elements lead and indium in the system, spin-orbit coupling (SOC) effects were considered in all electronic structure calculations (except during the geometry optimization phase). The primary electronic configurations considered were the 2s and 2p orbitals of O, C, and N; the 3s and 3p orbitals of P; the 4d and 5p orbitals of In; and the 1s orbital of H. A 3×3×1 Γ-centered k-point grid (Monkhorst-Pack scheme) was used for all surface calculations and SAM-modified surfaces. Γ-points were used for the optimization of isolated D4PA molecules. A cutoff energy of 600 eV was used for the projected augmented wave pseudopotential. To account for intermolecular van der Waals interactions, PBE-D3 (Grimme zero-damping) dispersion correction was employed during the geometry optimization.

[0070] Since the D4PA molecule contains two different phosphate anchoring groups, it is a typical double-anchor structure, and the C–C coupling between the dibenzocarbazole units leads to significant steric hindrance (see Figure 9 ). When D4PA is deprotonated and binds to ITO, the unique dimer structure promotes the formation of intramolecular hydrogen bonds between the two phosphate groups, thereby stabilizing the configuration. When D4PA binds to ITO, the P–O–In bond length is The corresponding binding energy is -4.42 eV. The rigid structure and intramolecular hydrogen bonding of the D4PA molecule enable it to achieve a more stable double-anchoring mode, enhancing the interfacial interaction with the substrate.

[0071] For practical verification, the D4PA molecules prepared in Example 1 and another common SAM material Me-4PACz (Chinese name: [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid) were interface-bound to the ITO substrate, and X-ray photoelectron spectroscopy (XPS) tests were performed. The sample preparation process is as follows: D4PA (0.35 mg ml -1 ) and Me-4PACz (0.25mgml-1 ) was added to the perovskite precursor solution (the preparation process of the perovskite precursor solution is as follows: 20.7 mg CsI, 25.3 mg MAI, 238.1 mg FAI and 791.6 mg PbI2 were dissolved in 1 mL DMF:DMSO mixed solvent with a volume ratio of 4:1, and the preparation concentration was 1.59 M and the stoichiometric ratio was Cs 0.05 FA 0.85 MA 0.1 A PbI3 perovskite precursor solution was prepared and thoroughly shaken for 120 seconds. 100 μL of the perovskite solution was dropwise applied to the ITO substrate. After 10 seconds of swirl coating, the film was first spin-coated at 1000 rpm for 10 seconds, then at 5000 rpm for 40 seconds. Eight seconds before the end of spin coating, 300 μL of chlorobenzene (CB) was added to the center of the film. The resulting perovskite film was annealed on a 100°C hotplate for 30 minutes, followed by 10 minutes at 120°C. After annealing, the perovskite was washed off with DMF solution to obtain an ITO / SAM film suitable for XPS analysis.

[0072] XPS test results are as follows Figure 10 As shown in the figure, the P 2p signal peak in the D4PA / ITO film shifts significantly to the high-energy region, while the signal peak in the Me-4PACz / ITO film does not shift significantly. This experimental result indicates that the interfacial interaction between the D4PA molecule and the ITO substrate is significantly stronger than that between the Me-4PACz and the ITO substrate.

[0073] Example 3

[0074] This example discusses the interaction between D4PA and the perovskite interface:

[0075] We calculated the interaction between D4PA and perovskite (see Figure 11 ). In this example, the binding energy between D4PA and the perovskite (FAPbI3) surface was calculated using the first-principles density functional theory method and VASP 6.4 software. The calculation process used PBE functional, DFT-D3 dispersion correction and spin-orbit coupling (SOC), projected augmented wave pseudopotential, cutoff energy of 600 eV, k-point sampling of 3×3×1 Γ point grid, and the residual force of all atoms during structure optimization was less than And introduce it on the model surface The vacuum layer is used to eliminate the periodic effect. The binding energy is calculated as: E binding =E slab+SAM -(E slab +E SAM ), where E slab+SAM is the total energy of the optimized interface, E slab and ESAM The optimized energies of the independent perovskite surface and D4PA molecule are shown in Figure 2. In the interaction between D4PA and the perovskite surface, the phosphate oxygen and Pb 2 + forms a coordination (P=O:→Pb) with a binding energy of -4.72eV. This is not only beneficial to improving the quality of perovskite, but also conducive to the efficient transport of carriers.

[0076] To further verify the DFT calculation results, we used the D4PA molecules and Me-4PACz prepared in Example 1 to interface with perovskite, and obtained D4PA and Me-4PACz doped perovskite films, and then performed X-ray photoelectron spectroscopy (XPS) tests. The film samples for XPS testing were prepared as follows: D4PA (0.35 mg ml -1 ) and Me-4PACz (0.25 mg ml -1 ) was added to the perovskite precursor solution (the preparation process of the perovskite precursor solution is as follows: 20.7 mg CsI, 25.3 mg MAI, 238.1 mg FAI and 791.6 mg PbI2 were dissolved in 1 mL DMF:DMSO mixed solvent with a volume ratio of 4:1, and the preparation concentration was 1.59 M and the stoichiometric ratio was Cs 0.05 FA 0.85 MA 0.1 A PbI3 perovskite precursor solution was prepared and thoroughly shaken for 120 seconds. 100 μL of the perovskite solution was dropwise applied to an ITO substrate. After 10 seconds of swirl coating, the film was first spin-coated at 1000 rpm for 10 seconds, then at 5000 rpm for 40 seconds. Eight seconds before the end of spin coating, 300 μL of chlorobenzene (CB) was added to the center of the film. The resulting perovskite film was annealed on a 100°C hotplate for 30 minutes, followed by 10 minutes at 120°C, yielding a perovskite film suitable for XPS analysis.

[0077] XPS test results are as follows Figure 12 As shown, it can be seen that the Pb 4f signal peak in the D4PA / PVK sample shifts significantly to the low energy region, and the shift amplitude is greater than that of the Me-4PACz / PVK sample, indicating a stronger interaction between the D4PA molecules and the perovskite layer.

[0078] Example 4

[0079] This example discusses the aggregation behavior of D4PA in perovskite:

[0080] We conducted dynamic light scattering (DLS) tests on the perovskite precursor solutions doped with Me-4PACz and D4PA at different storage times. The test samples were prepared by adding D4PA (0.1 mg ml -1) and Me-4PACz (0.1 mg ml -1 ) was added to the perovskite precursor solution (the preparation process of the perovskite precursor solution is as follows: 20.7 mg CsI, 25.3 mg MAI, 238.1 mg FAI and 791.6 mg PbI2 were dissolved in 1 mL DMF:DMSO mixed solvent with a volume ratio of 4:1, and the preparation concentration was 1.59 M and the stoichiometric ratio was Cs 0.05 FA 0.85 MA 0.1 perovskite precursor solution of PbI3).

[0081] The results are as follows Figure 13 As shown in the figure, it is not difficult to see that Me-4PACz exhibits significant molecular aggregation, with its particle size increasing from 211nm to 405nm within 12 hours. In contrast, the particle size of D4PA only increased from 62nm to 102nm, indicating that its aggregation tendency is significantly weaker. This difference verifies that the steric hindrance and conformational locking effects of D4PA molecules contribute to its uniform dispersion in the perovskite precursor solution.

[0082] Example 5

[0083] This example discusses the device performance of D4PA as an additive for inverse perovskite solar cells:

[0084] The inverse perovskite solar cell device structure used in this embodiment is ITO / SAM+PVK / C 60 / BCP / Ag, where PVK represents the perovskite material, and SAM is the D4PA molecule and Me-4PACz prepared in Example 1, respectively. The device preparation method is as follows: the glass / ITO substrate is sequentially treated with ultrasonic cleaning agent, deionized water, acetone and isopropanol for 20 minutes each, dried in an oven at 100°C, and then treated with oxygen plasma for 10 minutes, and then transferred to a nitrogen-filled glove box for standby use. 20.7 mg CsI, 25.3 mg MAI, 238.1 mg FAI and 791.6 mg PbI2 (containing 8% excess PbI2) were dissolved in 1 mL DMF:DMSO (volume ratio 4:1) mixed solvent to prepare a concentration of 1.59 M and a stoichiometric ratio of CsI. 0.05 FA 0.85 MA 0.1 A perovskite precursor solution of PbI3 was prepared to obtain a perovskite with a band gap of 1.53 eV. 10 mol% MACl was then added to the solution, stirred for 15 minutes, and then 0.35 mg ml -1 D4PA or 0.25mgml -1Me-4PAcz was mixed by oscillation for 120 seconds. 100 μL of the perovskite solution was dropped onto the ITO substrate. After standing for 10 seconds, it was spin-coated at 1000 rpm for 10 seconds, then at 5000 rpm for 40 seconds. 8 seconds before the end of spin coating, 300 μL of chlorobenzene was added to the center of the film. The resulting perovskite film was annealed on a 100°C hotplate for 30 minutes, then at 120°C for 10 minutes. For devices with surface passivation, 2 mg ml -1 pF-PEAI and 1 mg ml -1 The MAI was dissolved in a mixed solvent of IPA:DMF (volume ratio 150:1) and dynamically spin-coated on the surface of the prepared perovskite film at 5000 rpm for 30 seconds, followed by annealing at 100°C for 5 minutes. All spin-coating steps were completed in a nitrogen-filled glove box with a temperature of 18-22°C and a water and oxygen content of less than 5 ppm. Finally, the films were placed in a high vacuum (<5×10 -6 Torr) and 30nm C60, 6nm BCP and 100nm silver electrodes were thermally evaporated at a rate of A 125 nm magnesium fluoride layer was deposited on the back of the ITO substrate to enhance transmittance. The active area of ​​the device was defined by a metal mask and characterized as 0.0412 cm 2 .

[0085] Figure 14 The photovoltaic performance of perovskite solar cells based on D4PA and Me-4PACz was demonstrated. It is clear that the D4PA-based device achieved a maximum photoelectric conversion efficiency of 26.83%, far higher than the 24.97% of the Me-4PACz reference device. The D4PA-doped device achieved an open-circuit voltage of 1.200 V and a short-circuit current density of 26.11 mA / cm 2 , with a fill factor of 85.63%. Testing and certification by the Fujian Institute of Metrology, an authoritative third-party institution, has shown that the photoelectric conversion efficiency of the perovskite solar cell device prepared using the D4PA material as an additive has reached 26.72%, fully demonstrating the application value and broad prospects of this material in high-efficiency perovskite devices.

[0086] The compound D4PA, used as an additive in inverted planar perovskite solar cells, achieves one of the highest PCEs currently available for devices of this structure. This is due in part to the material's inherently twisted conformation, which inhibits molecular aggregation in the perovskite precursor solution. Furthermore, the multiple anchoring groups enhance the interaction with ITO and the perovskite, promoting the formation of high-quality perovskite crystal films and interfacial hole extraction and transport, resulting in a high-performance device. Furthermore, the device utilizes a one-step perovskite fabrication process, eliminating the need for a separate spin-coated hole transport layer, further simplifying the device fabrication process. The dibenzocarbazole alkylphosphonic acid dimer compound partially deposits to the bottom during processing, preventing the perovskite light-absorbing layer from directly contacting the transparent conductive substrate, thereby facilitating hole extraction and transport.

[0087] The above embodiment is based on Taking the compound D4PA in which n=3 and R is H in the general formula as an example, n in the dibenzocarbazole alkylphosphonic acid dimer of the present invention can be selected from any value between 1-5. The length of the alkyl chain will change the hydrophobicity of the molecule, and can also regulate the molecular self-assembly behavior and the interface anchoring conformation. At the same time, different substituents can also accurately regulate the properties of the material and the interface interaction, but these will not change the hole transport, interface anchoring and defect passivation properties of the material. Therefore, compounds with different alkyl chain lengths and substituents R are used as additives in trans perovskite solar cells like D4PA of the present invention, achieving comparable technical effects. When n is different and R groups are different, the compounds can also refer to Figure 1 The synthesis route shown in the figure can be carried out by simply replacing 1,4-dibromobutane and dibenzocarbazole (i.e., compound 1) with the corresponding reaction raw materials (the replaced reaction raw materials can be used in the same amount to participate in the reaction; other reaction reagents, amounts, and reaction conditions can remain unchanged).

[0088]

[0089]

[0090] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dibenzocarbazolidine phosphonic acid dimer compound, characterized in that: The compound uses dibenzocarbazole as a molecular skeleton, and two dibenzocarbazole derivative units are connected by a C-C single bond. The connection sites of the C-C single bond are respectively located at the 2nd and 11th positions of the two dibenzocarbazole units, and each dibenzocarbazole derivative unit has a phosphonic acid group connected by an alkyl chain.

2. The dibenzocarbazolidine phosphonic acid dimer compound according to claim 1, wherein Its structure is shown in general formula (A): Wherein, n is an integer of 1-5; the substituent R is selected from hydrogen atom, methyl, ethyl, methoxy, fluorine and chlorine, and the substitution sites are positions 4 and 9 of the dibenzocarbazole unit.

3. Use of the dibenzocarbazolidine phosphonic acid dimer compound according to any one of claims 1 to 2 in an inverse perovskite solar cell.

4. The use according to claim 3, characterized in that The dibenzocarbazolidine phosphonic acid dimer compound is added into the perovskite light absorption layer as an additive.

5. The use according to claim 4, characterized in that The perovskite light absorption layer is formed by adding the dibenzocarbazole alkylphosphonic acid dimer compound to a perovskite precursor solution for blending, and then co-depositing to form a perovskite light absorption layer containing the dibenzocarbazole alkylphosphonic acid dimer compound.

6. The use according to claim 4, characterized in that The inverse perovskite solar cell does not require a separate hole transport layer.

7. The use according to claim 6, characterized in that The perovskite light absorption layer is prepared by adding the dibenzocarbazole alkylphosphonic acid dimer compound to a perovskite precursor solution, and then spin-coating the mixture on a transparent conductive substrate, thereby forming a perovskite light absorption layer containing the dibenzocarbazole alkylphosphonic acid dimer compound on the transparent conductive substrate.

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