Indeno[3,2-b]carbazole compounds, preparation method thereof, monolayer self-assembled hole material, self-assembled monolayer and perovskite battery

Abstract

This invention relates to the field of optoelectronic materials technology, specifically to indolo[3,2-B]carbazole compounds and their preparation methods, monolayer self-assembled hole materials, self-assembled monolayers, and perovskite solar cells. The indolo[3,2-B]carbazole compounds are selected from compounds shown in the following structural formulas: where R is selected from any of the groups shown in the following structural formulas; n is any integer between 0 and 6; and R1 is selected from any of a carboxylic acid group, a sulfonic acid group, and a phosphate group. These indolo[3,2-B]carbazole compounds can be used to prepare self-assembled monolayers, which not only improve the poor wettability of SAM molecules to perovskite precursor solutions but also effectively passivate defects on the lower surface of perovskite, improving the hole extraction and transport capabilities of the monolayer self-assembled hole material, thereby enhancing the performance and stability of perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials technology, and more specifically, to indole[3,2-B]carbazole compounds and their preparation methods, monolayer self-assembled hole materials, self-assembled monolayers, and perovskite solar cells. Background Technology

[0002] Perovskite solar cells are solar cells that utilize perovskite-type organometal halide semiconductors as light-absorbing materials. They belong to the third generation of solar cells and are also known as novel concept solar cells. The structure of a perovskite solar cell includes several parts: a transparent conductive oxide layer, a perovskite layer, an electron transport layer, a hole transport layer, and a metal electrode. The main function of the hole transport layer is to facilitate the transport of photogenerated holes from the perovskite layer to the electrode (or positive electrode, anode), while simultaneously blocking the reverse flow of electrons, thereby helping to reduce charge recombination and improve the photoelectric conversion efficiency of the cell. Self-assembled monolayers (SAMs) have received widespread attention and research as one of the optional hole transport layers for high-efficiency inverted perovskite single-junction or tandem solar cells. The molecular dipoles, energy levels, and molecular arrangement of SAM molecules significantly affect the work function (WF) of the substrate and the wettability of the perovskite solution, thus affecting the efficiency and stability of the perovskite solar cell. Therefore, it is necessary to modify SAM molecules to improve the performance of self-assembled monolayers, thereby achieving higher cell efficiency and stability.

[0003] Current improvements to SAM molecules primarily focus on modifying the substituents or the structure of the parent core itself, such as using methoxy or halogen substituents. However, after the SAM material forms a self-assembled layer, the parent core surface directly contacts the perovskite layer, exposing mostly substituent aromatic groups. This introduces wettability issues into the perovskite layer. For example, the commonly used Me-4PACZ itself has poor wettability, requiring additional processes, such as adding a modification layer to improve wettability. Adding a modification layer not only increases production steps, time, and costs but may also affect the performance and stability of the final perovskite solar cell. Furthermore, SAM molecules lack effective passivation groups, making them prone to defects at the perovskite contact surface, affecting the cell's efficiency and stability.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide indolo[3,2-B]carbazole compounds and their preparation methods, monolayer self-assembled hole materials, self-assembled monolayers, and perovskite solar cells. This invention provides an indolo[3,2-B]carbazole compound that can be used to prepare self-assembled monolayers. It not only improves the poor wettability of SAM molecules to perovskite precursor solutions but also effectively passivates surface defects on the perovskite substrate, enhancing the hole extraction and transport capabilities of the monolayer self-assembled hole material, thereby improving the performance and stability of perovskite solar cells.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides an indolo[3,2-B]carbazole compound selected from compounds with the following structural formulas:

[0008] Wherein, R is selected from any one of the groups shown in the following structural formulas: n is any integer between 0 and 6, and R1 is selected from any one of carboxylic acid group, sulfonic acid group and phosphate group.

[0009] Secondly, embodiments of the present invention provide a method for preparing indodo[3,2-B]carbazole compounds, comprising: performing a monosubstitution reaction of indodo[3,2-B]carbazole to form an indodocarbazole intermediate containing an ester group of R; and then performing a hydrolysis reaction.

[0010] Thirdly, the present invention provides a monolayer self-assembled hole material comprising the indolo[3,2-B]carbazole compounds described in the foregoing embodiments.

[0011] Fourthly, the present invention provides a self-assembled monolayer, which is prepared by the monolayer self-assembled hole material described in the foregoing embodiments.

[0012] Fifthly, the present invention provides a perovskite solar cell comprising the self-assembled monolayer described in the foregoing embodiments.

[0013] The present invention has the following beneficial effects: The indo[3,2-B]carbazole compounds provided in the embodiments of the present invention retain the NH group of the parent nucleus and select specific R groups. Through effective hydrogen bonding, they can improve the problem of poor wettability of perovskite precursor solutions caused by commonly used SAM molecules, thereby improving the quality of perovskite films. At the same time, the retained NH group can effectively passivate defects on the lower surface of perovskite, improving the performance and stability of perovskite solar cells. The asymmetric structure of the indo[3,2-B]carbazole compounds can also increase the dipole moment of SAM molecules, improve the hole extraction and transport capabilities of SAM molecules, and thus enhance the performance of perovskite solar cells. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The contact angle of the perovskite precursor solutions of Poly-TPD and Me-4PACz in Example 2 of the present invention for the indodo[3,2-B]carbazole compounds provided in Example 2 of the present invention.

[0016] Figure 2 Surface images of the perovskite thin films in Application Example 2 and Application Comparative Example 2 provided in Detection Example 1 of the present invention;

[0017] Figure 3 for Figure 2 Statistical distribution of grain size in the graph;

[0018] Figure 4 A schematic diagram of the structure of a perovskite solar cell provided as an application example of the present invention;

[0019] Figure 5 PCE box-type distribution diagram of perovskite solar cells provided as an application example of the present invention;

[0020] Figure 6 A box-type distribution diagram of a perovskite solar cell provided as an application example of the present invention;

[0021] Figure 7 Jsc box-type distribution diagram of perovskite solar cells provided as an application example of the present invention;

[0022] Figure 8 A box-type distribution diagram of Voc in a perovskite solar cell provided as an application example of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] In a first aspect, the present invention provides an indolo[3,2-B]carbazole compound selected from compounds with the following structural formulas:

[0025] Wherein, R is selected from any one of the groups shown in the following structural formulas: n is any integer between 0 and 6, and R1 is selected from any one of carboxylic acid group, sulfonic acid group and phosphate group.

[0026] The indolo[3,2-B]carbazole compounds described in this invention can be used to prepare self-assembled monolayers. These indolo[3,2-B]carbazole compounds retain NH groups and employ specific R groups, enabling them to form effective hydrogen bonds. This improves the poor wettability of perovskite precursor solutions caused by conventional SAM molecules, thus enhancing the quality of perovskite films. Simultaneously, the NH groups in the indolo[3,2-B]carbazole compounds effectively passivate surface defects in perovskite, improving the performance and stability of perovskite solar cells. The two N groups in the indolo[3,2-B]carbazole, one linked to H and the other to R groups, result in an asymmetric structure in the final indolo[3,2-B]carbazole compound. This increases the dipole moment of the molecules, improving the hole extraction and transport capabilities of SAM molecules, ultimately enhancing the performance of perovskite solar cells.

[0027] It should be noted that "*—" in the embodiments of the present invention indicates the position of the substituent bond.

[0028] Specifically, n is any value between 0 and 6, such as 0, 1, 2, 3, 4, 5, and 6. That is, when n is 0, R1 or... It is directly linked to indolo[3,2-B]carbazole.

[0029] Specifically, R can be selected from any of the groups shown in the following structural formulas:

[0030] n is any integer between 1 and 5. More preferably, R is selected from... n is any integer between 2 and 4.

[0031] Secondly, embodiments of the present invention provide a method for preparing indodo[3,2-B]carbazole compounds, comprising: using indodo[3,2-B]carbazole to carry out a monosubstitution reaction to form an indodocarbazole intermediate containing an ester group of R.

[0032] There are various ways to form an indolo[3,2-B]carbazole intermediate containing an ester group (R). For example, indolo[3,2-B]carbazole is reacted with an ester containing R. Specifically, indolo[3,2-B]carbazole, a basic substance (e.g., including but not limited to sodium hydride), and the ester containing R are reacted. The molar ratio of indolo[3,2-B]carbazole to the ester containing R is 1:0.9-1.1, and the molar ratio of indolo[3,2-B]carbazole to the basic substance is 1:(0.2-0.4). The reaction temperature is 0-80°C, for example, any value between 0°C, 10°C, 15°C, 20°C, 30°C, 40°C, 60°C, 70°C, and 80°C, or any two values ​​between 0-80°C, preferably 20-40°C.

[0033] or

[0034] Indobenzo[3,2-B]carbazole is reacted with a halogenated alkane to form an indobenzo[3,2-B]carbazole intermediate containing an alkylene halogen; specifically, indobenzo[3,2-B]carbazole, a basic substance (e.g., including but not limited to sodium hydride), and a halogenated alkane are mixed and reacted. The halogenated alkane has the following structural formula: X represents a halogen, such as chlorine, bromine, and iodine; n is any integer between 0 and 6. It's understandable that when n is 0, this part can be skipped, and the process can proceed directly to the next step.

[0035] During the reaction, the amount of halogenated alkane used can be greater than the molar amount of indo[3,2-B]carbazole, but for cost or economic practicality, it is preferred that the molar ratio of indo[3,2-B]carbazole to the halogenated alkane is 1:(3.5-4.5); the molar ratio of indo[3,2-B]carbazole to the basic substance is 1:(0.9-1.1); the above reaction temperature is 0-80℃, for example, any value between 0℃, 10℃, 15℃, 20℃, 30℃, 40℃, 60℃, 70℃ and 80℃, or any two values ​​between 0-80℃, preferably 20-40℃.

[0036] An indolecarbazole intermediate containing an alkylene halogen is reacted with an ester, wherein the molar ratio of the indolecarbazole intermediate containing an alkylene halogen to the ester is 1:(0.9-1.1); the reaction temperature is 140-180℃.

[0037] Subsequently, the indolocarbazole intermediate containing the R-ester group undergoes a hydrolysis reaction. Specifically, the indolocarbazole intermediate containing the R-ester group is mixed with a silane compound and reacted; the reaction temperature is 0-60°C, for example, any value between 0°C and 80°C, or any range between any two values, preferably 20-40°C.

[0038] Thirdly, the present invention provides a monolayer self-assembled hole material, which includes the indo[3,2-B]carbazole compound described in the foregoing embodiments, for example, by mixing the indo[3,2-B]carbazole compound with a solvent to form a monolayer self-assembled hole material.

[0039] Fourthly, the present invention provides a self-assembled monolayer, which is prepared by the monolayer self-assembled hole material described in the foregoing embodiments. Specifically, the above-mentioned monolayer self-assembled hole material is coated and dried to form a self-assembled monolayer.

[0040] Fifthly, the present invention provides a perovskite solar cell comprising the self-assembled monolayer described in the foregoing embodiments.

[0041] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0042] Example 1

[0043] This invention provides a method for preparing indolo[3,2-B]carbazole compounds, which are synthesized according to the following synthetic route:

[0044]

[0045] The specific process is as follows:

[0046] Formation of Intermediate 1: Indodo[3,2-B]carbazole (500 mg, 1.95 mmol) and 100 mL DMF were added to a two-necked flask with a magnetic stirrer. The mixture was stirred, and a 10 mL DMF dispersion of NaH (wt% = 60%, 240 mg, 6.0 mmol, 3.0 eq) was added dropwise at room temperature. The reaction was continued for 30 min. A 10 mL DMF solution of diethyl(2-bromoethyl)phosphonate (480 mg, 1.96 mmol) was slowly added dropwise. The addition was completed in approximately 1 h. The reaction was continued for 4 h. The reaction was quenched with 200 mL of water, adjusted to neutral with dilute hydrochloric acid, and extracted using EA. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was purified by column chromatography to give 220 mg of a white solid (i.e., Intermediate 1) (yield 27%).

[0047] The characterization data for intermediate 1 are as follows:1 H NMR(400MHz,Chloroform-d)δ8.18(d,J=7.7Hz,1H),8.12(d,J=7.7Hz,1H),8.04(s,2H),8.01(s,1H),7.54-7.46(m,1H), 7.44(d,J=3.6Hz,3H),7.29-7.19(m,2H),4.79-4.66(m,2H),4.19-4.05(m,4H),2.42-2.28(m,2H),1.32(t,J=7.1Hz,6H).

[0048] Formation of indolo[3,2-B]carbazole compounds: Under nitrogen protection, intermediate 1 (100 mg, 0.24 mmol) was weighed and dissolved in dry dichloromethane. 0.2 mL of trimethylbromosilane was added, and the reaction was allowed to proceed overnight at room temperature. After overnight reaction, 3 mL of methanol was added for quenching, followed by the addition of 0.5 mL of water and stirring for one day. The mixture was filtered to obtain 75 mg of a grayish-green solid (i.e., indolo[3,2-B]carbazole compounds) (yield 87%).

[0049] The characterization data of indo[3,2-B]carbazole compounds are as follows: 1 H NMR(400MHz,DMSO-d6)δ11.11(s,1H),8.29-8.15(m,4H),7.54-7.43(m,3H),7.39(t ,J=7.6Hz,1H),7.17(dt,J=11.7,7.0Hz,2H),4.77-4.57(m,2H),2.18-2.04(m,2H).

[0050] Example 2

[0051] This invention provides a method for preparing indolo[3,2-B]carbazole compounds, which are synthesized according to the following synthetic route:

[0052]

[0053] The specific process is as follows:

[0054] Formation of Intermediate 2: Indodo[3,2-B]carbazole (1000 mg, 3.9 mmol) and 300 mL DMF were added to a two-necked flask with a magnetic stirrer. The mixture was stirred, and a 100 mL DMF dispersion of NaH (wt% = 60%, 210 mg, 5.3 mmol, 1.2 eq) was added dropwise at room temperature. The reaction was continued for 30 min. A 30 mL DMF solution of diethyl(2-bromopropyl)phosphonate (1020 mg, 3.9 mmol) was slowly added dropwise. The addition was completed in approximately 1 h. The reaction was continued for 4 h. The reaction was quenched with 500 mL of water, adjusted to neutral with dilute hydrochloric acid, and extracted using EA. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was purified by column chromatography to give 600 mg of a yellowish-white paste-like solid (i.e., Intermediate 2) (yield 36%).

[0055] The characterization data for intermediate 2 are as follows: 1 H NMR(400MHz,Chloroform-d)δ8.17(d,J=7.6Hz,1H),8.11(d,J=7.6Hz,1H),8.03(d,J=2.3Hz,2H),7.50-7.39(m,4H),7.24-7.16(m ,2H),4.52(t,J=7.1Hz,2H),4.14-3.99(m,4H),2.28(dt,J=14.6,7.7Hz,2H),1.83(dt,J=18.5,7.7Hz,2H),1.26(t,J=7.1Hz,6H).

[0056] Formation of indolo[3,2-B]carbazole compounds: Under nitrogen protection, intermediate 2 (196 mg, 0.45 mmol) was weighed and dissolved in dry dichloromethane. 0.3 mL of trimethylbromosilane was added, and the reaction was allowed to proceed overnight at room temperature. After overnight reaction, 3 mL of methanol was added for quenching, followed by the addition of 0.5 mL of water and stirring for one day. The mixture was filtered to obtain 112 mg of a grayish-green solid (i.e., indolo[3,2-B]carbazole compounds) (yield 66%).

[0057] The characterization data of indo[3,2-B]carbazole compounds are as follows: 1 H NMR (400MHz, DMSO-d6) δ11.09(s,1H),8.32(s,1H),8.23(dd,J=7.8,4.7Hz,2H),8.16(s,1H),7.61(d,J=8.2Hz, 1H),7.53-7.33(m,3H),7.16(q,J=7.0Hz,2H),4.55(t,J=6.9Hz,2H),2.06(m,2H),1.60(dt,J=16.7,8.0Hz,2H).

[0058] Example 3

[0059] This invention provides a method for preparing indolo[3,2-B]carbazole compounds, which are synthesized according to the following synthetic route:

[0060]

[0061] Specifically,

[0062] Formation of Intermediate 3: Indodo[3,2-B]carbazole (256.3 mg, 1.0 mmol) and 20 mL DMF were added to a two-necked flask with a magnetic stirrer. The mixture was stirred, and a 10 mL DMF dispersion of NaH (wt% = 60%, 40 mg, 1.0 mmol, 1.0 eq) was added dropwise at room temperature. The reaction was continued for 60 min. A 20 mL DMF solution of 1,4-dibromobutane (863 mg, 4.0 mmol) was slowly added dropwise. The addition was completed in approximately 0.5 h. The reaction was continued for 4 h. The reaction was quenched with 100 mL of water, adjusted to neutral with dilute hydrochloric acid, and extracted using EA. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was purified by column chromatography to give 73 mg of a white solid (i.e., Intermediate 3) (yield 19%).

[0063] Characterization data of intermediate 3: 1 H NMR(400MHz,Chloroform-d)δ8.18(d,J=7.8Hz,1H),8.13(d,J=7.7Hz,1H),7.99(s,2H),7.46(dt,J=14.3,5.7Hz,4 H), 7.22 (d, J = 7.8Hz, 2H), 4.46 (s, 2H), 3.40 (t, J = 6.5Hz, 2H), 2.15 (p, J = 7.0Hz, 2H), 1.98 (dt, J = 14.1, 6.6Hz, 2H).

[0064] Formation of intermediate 4: Under nitrogen protection, 100 mg (0.25 mmol) of intermediate 3 was weighed and added to 8 mL of triethyl phosphite. The mixture was refluxed at 160 °C for 5 h. After cooling to room temperature, the reaction mixture was evaporated to dryness. The crude product was purified by column chromatography to obtain 91 mg of a brownish-yellow paste (yield: 84%).

[0065] Characterization data of intermediate 4: 1H NMR(400MHz,Chloroform-d)δ8.18(d,J=7.7Hz,1H),8.13(d,J=7.7Hz,1H),8.05(d,J=9.2Hz,2H),7.97(s,1H),7.51-7.37( m,4H),7.25-7.16(m,2H),4.43(t,J=7.0Hz,2H),4.08-3.95(m,4H),2.12-2.01(m,2H),1.78(s,6H),1.23(t,J=7.1Hz,6H).

[0066] Formation of indolo[3,2-B]carbazole compounds: Under nitrogen protection, intermediate 2 (105 mg, 0.25 mmol) was weighed and dissolved in dry dichloromethane. 0.2 mL of trimethylbromosilane was added, and the reaction was allowed to proceed overnight at room temperature. After overnight reaction, 3 mL of methanol was added for quenching, followed by the addition of 0.5 mL of water and stirring for one day. The mixture was filtered to obtain 53 mg of a grayish-green solid (i.e., indolo[3,2-B]carbazole compounds) (yield 57%).

[0067] The characterization data of indo[3,2-B]carbazole compounds are as follows: 1 H NMR (400MHz, DMSO-d6) δ11.06(s,1H),8.30(s,1H),8.24(t,J=8.1Hz,2H),8.15(s,1H),7.56(d,J=8.2Hz,1H) ,7.50-7.33(m,3H),7.15(td,J=7.4,3.9Hz,2H),4.46(t,J=7.2Hz,2H),1.93(s,2H),1.57(d,J=20.5Hz,4H).

[0068] Application examples

[0069] Perovskite solar cells were prepared using the indolo[3,2-B]carbazole compounds obtained in Examples 1-3, respectively. The structure of the perovskite solar cells was ITO glass / hole transport layer / Cs. 0.22 FA 0.78 Pb(I 0.865 Br 0.135 )3 / C 60 The structure of the / BCP / Cu battery is as follows: Figure 4 As shown. The specific preparation method is as follows:

[0070] ① Substrate preparation: The etched ITO substrate is ultrasonically cleaned with detergent, deionized water, acetone and isopropanol for 15 minutes in sequence, dried in a nitrogen atmosphere, and then treated with ultraviolet ozone for 30 minutes to remove organic impurities from the surface of the ITO substrate.

[0071] ②Preparation of hole transport layer: The indodo[3,2-B]carbazole compounds of Examples 1, 2, and 3 were dissolved in DMF solvent to prepare 0.5 mg / mL solutions. Each solution was coated on the surface of an ITO substrate and annealed and dried.

[0072] ③Preparation of perovskite layer: 1.4 M Cs 0.22 FA 0.78 Pb(I 0.865 Br 0.135 A perovskite layer was prepared by spin-coating a DMF:DMSO (4:1) precursor solution of 3 onto a hole transport layer at 3000 rpm for 25 s. The perovskite film was then treated by a vacuum method and annealed at 100 °C for 10 min to obtain the perovskite layer.

[0073] ④ Electron transport layer fabrication: Electron transport layer fabrication: A 20 nm thick C layer was deposited by thermal evaporation at a rate of 0.1 Å / s. 60 The layer serves as an electron transport layer. Subsequently, a 5 nm layer of BCP is deposited at a rate of 0.1 Å / s.

[0074] ⑤ Electrode preparation: In a vacuum chamber at 5 × 10 4 A 100 nm thick copper electrode was deposited under high vacuum conditions.

[0075] Comparative Example 1: The reported molecule IDCz-3 was dissolved in DMF to prepare a 0.5 mg / mL solution. A perovskite solar cell was formed according to the above method. The perovskite solar cell structure was the same as that of Application Example 1. The structural formula of IDCz-3 is as follows:

[0076]

[0077] Comparative Example 2: Poly-TPD was dissolved in a mixed solvent of chlorobenzene to prepare a 2 mg / ml solution, and a perovskite cell was formed according to the above method. The perovskite cell structure was the same as that of the perovskite cell in Application Example 1.

[0078] The inventors observed the spreading of the perovskite precursor solution during the preparation of the perovskite batteries in Application Examples and Comparative Examples 1-2. They observed that the wettability of the hole transport layer formed by the indodo[3,2-B]carbazole compounds in Examples 1-3 was significantly improved compared to the hole transport layer in Comparative Example 2, which was more conducive to the spreading of the perovskite precursor solution, resulting in a perovskite film with better crystallization and more uniform distribution.

[0079] Furthermore, to more accurately evaluate the improvement in wettability, the contact angles of films formed using Poly-TPD, Me-4PACz (comparative Example 2), and indo[3,2-B]carbazole compounds (Example 2) with the perovskite precursor solution were measured. The results are as follows: Figure 1 As shown, the contact angle of the film formed in Example 2 is 8.2°, which is much smaller than that of Comparative Example 2 (47.8°) and Me-4PACz (30.4°). This demonstrates that the indodo[3,2-B]carbazole compounds provided in this embodiment of the invention can effectively improve the wettability of the hole transport layer to the perovskite precursor solution.

[0080] Detection Example 1

[0081] The surface of the perovskite film prepared on the films formed by Poly-TPD used in Comparative Example 2 and the indodo[3,2-B]carbazole compounds in Example 2 was further tested using SEM.

[0082] The results are as follows Figure 2 and Figure 3 As shown. Figure 3 for Figure 2 A statistical chart of grain size, from Figure 2 , 3 It is evident that the perovskite film prepared on the indo[3,2-B]carbazole compound in Example 2 has larger grains and higher quality than the film prepared on the Poly-TPD film. This is beneficial for reducing defects in the perovskite film, improving the Voc of the perovskite solar cell, and thus improving the efficiency of the perovskite solar cell.

[0083] Detection Example 2

[0084] The results for PCE, FF, Voc, and Jsc of the perovskite solar cells in the above application examples and comparative examples 1-2 are shown in Table 1 below. Figures 5 to 8 .

[0085] Table 1 Test Results

[0086]

[0087] According to Table 1 and Figures 5 to 8 It can be seen that the Voc of the perovskite solar cells formed in Examples 1-3 is significantly higher than that of the perovskite solar cells in Application Examples 1 and 2. This indicates that the NH functional group retained in the indo[3,2-B]carbazole compound provided in the embodiments of the present invention can effectively interact with the lower surface of the perovskite, passivating unnecessary defects on the lower surface, thereby significantly improving the Voc of the cell. At the same time, better hole extraction and transport capabilities and more matched energy levels significantly improve the fill factor in the application examples. Ultimately, this effectively improves the cell efficiency.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An indolo[3,2-B]carbazole compound, characterized in that, It is selected from compounds with the following structural formulas: Wherein, R is selected from any one of the groups shown in the following structural formulas: n is any integer between 0 and 6, and R1 is selected from any one of carboxylic acid group, sulfonic acid group and phosphate group.

2. The indolo[3,2-B]carbazole compound according to claim 1, characterized in that, R is selected from any one of the groups shown in the following structural formulas: n is any integer between 1 and 5.

3. The indo[3,2-B]carbazole compound according to claim 1 or 2, characterized in that, R is selected from n is any integer between 2 and 4.

4. A method for preparing the indolo[3,2-B]carbazole compound according to claim 1, characterized in that, include: Indodo[3,2-B]carbazole was used to carry out a monosubstitution reaction to form an indodo[3,2-B]carbazole intermediate containing an R ester group; Then a hydrolysis reaction occurs.

5. The preparation method according to claim 4, characterized in that, The step of forming the R-containing ester group of indolo[3,2-B]carbazole intermediate includes reacting indolo[3,2-B]carbazole with the R-containing ester, wherein the reaction conditions include: the molar ratio of indolo[3,2-B]carbazole to the R-containing ester is 1:0.9-1.1, and the reaction temperature is 0-80°C.

6. The preparation method according to claim 4, characterized in that, The steps for forming the R-containing ester group of indolo[3,2-B]carbazole include: reacting indolo[3,2-B]carbazole with a halogen-substituted alkane to form an indolocarbazole intermediate containing an alkylene halogen. Then it reacts with the ester. The structural formula of the halogenated alkyl group is as follows: n is any integer between 0 and 6, and X represents halogen; The reaction temperature between the indodo[3,2-B]carbazole and the halogenated alkane is 0-80℃. The molar ratio of the indolecarbazole intermediate containing alkyl halogen to the ester is 1:(0.9-1.1); the reaction temperature is 140-180℃.

7. The preparation method according to claim 4, characterized in that, The hydrolysis reaction includes: mixing the R-containing ester-group indolocarbazole intermediate with a silane compound and reacting them; Reactant conditions include a temperature of 0-60℃.

8. A monolayer self-assembled hole material, characterized in that, It includes the indodo[3,2-B]carbazole compounds as described in claim 1.

9. A self-assembled monolayer, characterized in that, It is prepared by the monolayer self-assembled hole material as described in claim 8.

10. A perovskite solar cell, characterized in that, It includes the self-assembled monolayer as described in claim 9.

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