Thiazine derivative self-assembled monolayer hole transport material and preparation method and application thereof

Abstract

The application provides a kind of thiazine derivative self-assembly monolayer hole transport material and its preparation method and application, and belongs to the technical field of solar energy industry, the hole transport material has the structure shown in formula I, the self-assembly monolayer hole transport material of the application has simple structure, high hole transport property, strong interface passivation ability, high thermal stability, is suitable for large-scale application, it can improve molecular packing and improve the hole transport performance of material with rigid conjugated large plane thiazine as mother nucleus;With phosphoric acid group as the end, single molecule self-assembly and passivation perovskite interface can be realized, energy loss at the interface is reduced, and the battery performance is improved. When the synthesized material is used as the hole transport layer of the inverted perovskite solar cell, the photoelectric conversion efficiency of more than 24% can be obtained without doping, and the life and stability of the perovskite solar cell are greatly improved, which is expected to help the perovskite solar cell to realize industrialization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar energy industry, and relates to a thiazine derivative self-assembled monolayer hole transport material and a preparation method and application thereof. BACKGROUND

[0002] As a new generation of photovoltaic technology, perovskite solar cells (PSCs) have the advantages of simple preparation process, easy-to-adjust materials, low cost, etc., and the latest certified efficiency has reached 26.2% (National Renewable Energy Laboratory, NREL, 2023). There are two main structural types of perovskite solar cells, one is the forward n-i-p structure, and the other is the reverse p-i-n structure. Compared with the n-i-p structure, the p-i-n structure is more suitable for making large-area and stacked solar cells, because it can use low-temperature processes and more types of carrier extraction layers, and has higher commercial prospects. However, the p-i-n structure also faces a challenge, that is, how to improve the interface quality and stability between the hole selective layer and the perovskite. At present, the commonly used hole transport materials (HTMs) for reverse devices are inorganic material nickel oxide (NiOx) and organic polymer material poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). Among them, there is an energy level mismatch and defect state between nickel oxide and perovskite, which leads to voltage loss and interface degradation; PTAA is high in price, unstable in product batch, and low in film infiltration, which limits the further improvement of device performance. Therefore, developing high-performance, new-type hole transport materials for reverse devices is crucial for the performance of the device. Self-assembled monolayer (SAM) as a hole transport material has the characteristics of simple structure and flexible design, and can effectively adjust the interface energy level and reduce the defect state based on molecular engineering. At the same time, this kind of material also shows the advantages of small parasitic absorption, less material consumption, and compatibility with stacked perovskite solar cells, simplifying the manufacturing of large-area devices, etc., and has become a popular choice for preparing high-efficiency perovskite solar cells. Therefore, developing new-type SAM materials with simple structure, low cost, and excellent performance is a key problem to be solved for promoting the industrialization process of PSCs.

[0003] Hole transport materials (HTMs) are an important component of PSCs, playing a key role in the efficiency and stability of the cells. Poly[2,6-(4-phenyl-phenyl)-4,8-bis(2-thienyl)-benzo-1,2-dithiophen-3-yl] (PTAA) is the most commonly used HTM in high-efficiency inverted PSCs, but the many problems of PTAA itself have seriously hindered the industrialization process of inverted PSCs: first, the price of PTAA is as high as 1980 $ / g, dozens of times that of gold, which makes it impossible to be used on a large scale; second, the hole mobility of PTAA itself is relatively low (about 10 5 cm 2 V -1 s -1 ), and it is necessary to add doping agents such as lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (F4TCNQ) to improve the hole transport performance, but these water-absorbing dopants will cause the decomposition of perovskite, greatly affecting the long-term stability of the cell; finally, as a kind of polymer, the molecular weight and photovoltaic performance of PTAA will change with the synthesis batch, which is not conducive to industrial application.

[0004] Therefore, developing a new type of SAM material with simple structure, low cost and excellent performance is a key problem to be solved to promote the industrialization process of PSCs. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a thiazine derivative self-assembled monolayer hole transport material and a preparation method and application thereof. The self-assembled monolayer hole transport material of the present application is a non-doped hole transport material, which takes carbazole derivative as the mother nucleus and butyl phosphate as the anchoring group, and has simple structure, high hole transport property, strong interface passivation ability and high thermal stability.

[0006] To achieve the purpose of the present application, the following technical solutions are adopted:

[0007] On the one hand, the present application provides a thiazine derivative self-assembled monolayer hole transport material, which has the following structure shown in formula I:

[0008] .

[0009] The self-assembled monolayer hole transport material of the present application takes thiazine with rigid conjugated large plane as the mother nucleus, can improve the molecular packing and improve the hole transport performance of the material; takes phosphoric acid group as the terminal, can realize the self-assembly of single molecule and passivate the perovskite interface, reduce the energy loss at the interface, and improve the battery performance. When the synthesized material is used as the hole transport layer of the inverted perovskite solar cell, the photoelectric conversion efficiency of >24% can be obtained without doping, and the service life and stability of the perovskite solar cell are greatly improved, which is expected to help the perovskite solar cell to realize industrialization.

[0010] In another aspect, the present application provides a preparation method of the thiazine derivative self-assembled monolayer hole transport material as described above, comprising the following steps:

[0011] (1) reacting the compound of formula II with the compound of formula III to obtain the compound of formula IV, and the reaction formula is as follows:

[0012] ;

[0013] (2) hydrolyzing the compound of formula IV to obtain the self-assembled monolayer hole transport material based on polycarbazole derivative of formula I, and the reaction formula is as follows:

[0014] ;

[0015] wherein R1 and R2 are independently selected from C1-C5 alkyl, and X is selected from halogen.

[0016] In the present application, R1 and R2 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl and the like, and ethyl is preferred. X is selected from F, Cl, Br or I, and Br is preferred.

[0017] Preferably, the molar ratio of the compound of formula II to the compound of formula III in step (1) is 1:1-1.5, for example 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0018] Preferably, the reaction in step (1) is carried out in the presence of a catalyst selected from cuprous iodide.

[0019] Preferably, the reaction in step (1) is carried out in the presence of a basic substance selected from potassium carbonate and / or sodium carbonate.

[0020] Preferably, the reaction in step (1) is carried out in an organic solvent selected from N,N'-dimethylacetamide.

[0021] Preferably, the temperature of the reaction in step (1) is 160-180℃ (e.g. 160℃, 162℃, 164℃, 166℃, 168℃, 170℃, 172℃, 174℃, 176℃ or 180℃, etc.), and the reaction time is 20-24 h (e.g. 20 h, 21 h, 22 h, 23 h or 24 h, etc.).

[0022] Preferably, the hydrolysis reaction in step (2) is carried out in the presence of trimethylsilyl bromide.

[0023] Preferably, the molar ratio of trimethylsilyl bromide to the compound of formula IV is 2:1-4:1 (e.g. 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1 or 4:1, etc.).

[0024] Preferably, the hydrolysis reaction in step (2) is carried out in an organic solvent selected from dichloromethane, trichloromethane.

[0025] Preferably, the hydrolysis reaction in step (2) is carried out at room temperature, and the reaction time is 12-18 hours (e.g. 12 hours, 13.5 hours, 15 hours, 16.5 hours or 18 hours, etc.).

[0026] In another aspect, the present application provides a perovskite solar cell comprising a self-assembled monolayer, wherein the self-assembled monolayer comprises the self-assembled monolayer hole transport material based on polycarbazole derivatives as described above.

[0027] Preferably, the perovskite solar cell is a trans perovskite solar cell.

[0028] Preferably, the perovskite solar cell comprises, from top to bottom, a cathode layer, an electron transport layer, a passivation layer, a perovskite light absorbing layer, a self-assembled monolayer, a hole transport layer, and an anode layer, which are sequentially arranged.

[0029] Preferably, the self-assembled monolayer is obtained by coating a solution of the self-assembled monolayer hole transport material based on polycarbazole derivatives as described above onto the surface of the hole transport layer, and then performing thermal annealing.

[0030] Preferably, the temperature of the thermal annealing is 80-120℃ (e.g. 80℃, 90℃, 100℃, 110℃ or 120℃, etc.), and the time of the thermal annealing is 5-20 minutes (e.g. 5 minutes, 8 minutes, 10 minutes, 13 minutes, 15 minutes, 18 minutes or 20 minutes, etc.).

[0031] In the present application, the perovskite light absorbing layer is prepared by coating (e.g. spin coating) a perovskite solution onto the surface of the self-assembled monolayer.

[0032] In the present application, the coating method can be slot coating or spin coating.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] The self-assembled monolayer hole transport material of the present application has simple structure, high hole transport property, strong interface passivation ability and high thermal stability, and is suitable for large-scale application. The thiazine with rigid conjugated large plane as the mother nucleus can improve the molecular packing and enhance the hole transport performance of the material. The phosphoric acid group as the terminal can realize the self-assembly of single molecule and passivation of perovskite interface, reduce the energy loss at the interface, and improve the battery performance. When the synthesized material is used as the hole transport layer of the inverted perovskite solar cell, a photoelectric conversion efficiency of > 24% can be obtained without doping, and the service life and stability of the perovskite solar cell are greatly improved, which is expected to help the perovskite solar cell to realize industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is the nuclear magnetic hydrogen spectrum of intermediate 1;

[0036] Figure 2 is the nuclear magnetic hydrogen spectrum of compound A1;

[0037] Figure 3 is the IV curve of the solar cell prepared by using compound A1 as a hole transport material;

[0038] Figure 4 is a structural schematic diagram of a perovskite solar cell. DETAILED DESCRIPTION

[0039] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application, and should not be regarded as specific limitations on the present application.

[0040] Example 1

[0041] Synthesis of compound A1

[0042]

[0043] Step 1: synthesis of intermediate 1

[0044] Under nitrogen atmosphere, the starting material 1 (1.58 g, 3.0 mmol) and starting material 2 (0.91 g, 3.1 mmol) were dissolved in 25 mL of N,N'-dimethylacetamide, followed by the addition of K2CO3(0.83 g, 6.0 mmol) and cuprous iodide (0.06 g, 6.0 mmol). The reaction mixture was reacted at 180 °C for 24 h. After the reaction was completed, it was cooled to room temperature. Diluted with water, then extracted with dichloromethane. The organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated. The crude product was separated by silica gel column chromatography to obtain a white solid (0.78 g, 52%).

[0045] The nuclear magnetic hydrogen spectrum of intermediate 1 is shown in Figure 1 1 H NMR (400 MHz, DMSO-d6) δ 9.03-8.94 (m, 1H), 8.43-8.36 (m, 1H), 8.16-8.10 (m, 1H), 8.07 (s, 1H), 7.67-7.59 (m, 2H), 7.58-7.47 (m, 3H), 7.47-7.35 (m, 4H), 7.35-7.27 (m, 5H), 7.26 (s, 1H), 7.18 (dd, J = 5.5, 3.2 Hz, 1H), 4.05-3.87 (m, 6H), 1.92 (dtd, J = 11.8, 9.2, 0.7 Hz, 2H), 1.74-1.56 (m, 4H), 1.30 (td, J = 7.2, 0.7 Hz, 6H).

[0046] Step 2: Synthesis of compound A1

[0047] In a 50 mL oven-dried round-bottom flask, intermediate 1 (0.36 g, 0.5 mmol) was dissolved in 20 mL of dichloromethane. Trimethylsilyl bromide (0.612 g, 0.528 mL, 4 mmol) was added dropwise to the well-stirred mixture at room temperature. After 12 h, the mixture was carefully transferred to a 100 mL round-bottom flask and concentrated under reduced pressure. A magnetic stir bar and 20 ml of methanol were then added sequentially. The mixture was stirred at room temperature for 4 h, the mixture was filtered, rinsed with methanol (3 x 5 mL), and the combined filtrate was concentrated under reduced pressure to obtain a solid as a crude product. Recrystallization with methanol / dichloromethane / ether gave a white solid (0.26 g, 72%).

[0048] The nuclear magnetic hydrogen spectrum of compound A1 is shown in Figure 2 1 ​​H NMR (400 MHz, DMSO-d6) δ 9.03-8.94 (m, 1H), 8.43-8.36 (m, 1H), 8.34 (s, 2H), 8.16-8.10 (m, 1H), 8.07 (s, 1H), 7.67-7.59 (m, 2H), 7.58-7.48 (m, 3H), 7.48-7.40 (m, 2H), 7.40-7.24 (m, 8H), 7.18(dd, J = 5.5, 3.1 Hz, 1H), 3.90 (s, 2H), 1.93-1.79 (m, 2H), 1.75-1.62 (m,4H).

[0049] Example 2

[0050] Perovskite solar cells were prepared using self-assembled monolayer material A1, with the structure as shown in Figure 4 Glass / FTO / NiOx / SAM / PVSK / C60 / SnO2 / Ag. The specific device preparation process is as follows: First, the FTO conductive glass substrate was pretreated. The FTO glass was ultrasonically cleaned in detergent, deionized water, ethanol and acetone for 15 minutes respectively, and then dried in a 75°C oven. The glass was treated with ultraviolet ozone for 10 minutes before use, and then a NiOx layer was prepared by spin coating in air. After filtering the 5 mg / mL NiOx aqueous solution through a 0.22 μm PTFE filter membrane, it was added to the surface of the FTO substrate, and rotated at 5000 rpm for 30 s on a film applicator, and then annealed at 120°C for 15 minutes. After the preparation of the NiOx layer, the substrate was transferred to a nitrogen glove box for the preparation of the self-assembled monolayer (SAM). 110 μL of A1 ethanol solution with a concentration of 0.35 mg / mL was added to the center of the substrate, and spin coated at 5000 rpm for 30 s, and then annealed at 100°C for 10 minutes. The perovskite layer was deposited by two-step spin coating, and 110 μL of perovskite precursor solution (FA 0.9 MA 0.05 Cs. 0.05PbI31.5M, DMF:DMSO volume ratio = 4:1) was added in the center of the substrate, the first step was rotated at 2000 rpm for 20 s and the second step was rotated at 4500 rpm for 35 s. 10 s before the end of the second spin-coating step, 110 μΐ of anisole was uniformly added in the center of the substrate, followed by thermal annealing at 110 °C for 20 min. After waiting for the perovskite film to be annealed and cooled to room temperature, the passivation layer was prepared. 110 μΐ of PDADI2 (i.e. 1,3-diaminopropanedihydroiodide was dissolved in isopropyl alcohol (IPA) with a concentration of 0.5 mg / mL) solution was added in the center of the substrate, and was rotated at 5000 rpm for 30 s on a spin coater, and was annealed at 100 °C for 5 min on a constant temperature hot stage. After waiting for the annealing to complete, the cell was transferred to an evaporation system, and 21 nm of C60 was deposited on the perovskite layer by vacuum thermal evaporation; then, 25 nm of Sn02 was deposited by atomic layer deposition (ALD) at 90 °C. Finally, after the excess film layer on the common terminal was scraped off, a 100 nm thick Ag electrode was deposited by vacuum evaporation under a mask.

[0051] Perovskite solar cell devices were prepared and characterized according to the above procedure based on A1 prepared in Example 1. The current-voltage (J-V) characteristic curve of the cell device performance is shown in Figure 3 , with an open-circuit voltage Voc of 1.165 V, a short-circuit current density Jsc of 25.20 mA / cm 2 , a fill factor FF of 0.845, and a power conversion efficiency of 24.81%.

[0052] Comparative Example 1

[0053] Example 2 was replaced by [4-(10H-phenothiazin-10-yl)butyl]phosphonic acid (4PAPT), which has the following structure:

[0054]

[0055] The open-circuit voltage Voc of the cell prepared was 1.10 V, the short-circuit current density Jsc was 26.1 mA / cm 2 , the fill factor FF was 0.795, and the power conversion efficiency was 22.8%.

[0056] Comparative Example 2

[0057] Example 2 was replaced by the following material, which has the following structure:

[0058]

[0059] The open-circuit voltage Voc of the cell prepared was 1.08 V, the short-circuit current density Jsc was 25.4 mA / cm2 The fill factor FF is 0.734, and the photoelectric conversion efficiency is 20.8%.

[0060] Table 1 is the parameter of the transverse perovskite solar cell.

[0061] Table 1

[0062]

[0063] As shown in Table 1, the photoelectric conversion efficiency of the rigid conjugated large plane thiazine system self-assembled monomolecular hole transport material prepared by the present application is higher than that of the comparative examples 1 and 2, and since the A1 energy level is more matched with the perovskite, the voltage and fill factor are obviously improved, and the photoelectric conversion efficiency of up to 24.81% is obtained.

[0064] The applicant declares that the thiazine derivative self-assembled monolayer hole transport material of the present application, the preparation method and the application thereof are illustrated by the above examples, but the present application is not limited to the above examples, that is, it does not mean that the present application must rely on the above examples to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the selected raw materials, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A thiazide derivative self-assembled monolayer hole transport material, characterized in that, The thiazide derivative self-assembled monolayer hole transport material has the structure shown in Formula I: 。 2. The method for preparing the thiazide derivative self-assembled monolayer hole transport material according to claim 1, characterized in that, The preparation method includes the following steps: (1) The compound of formula II reacts with the compound of formula III to give the compound of formula IV, and the reaction formula is as follows: ； (2) The compound shown in Formula IV undergoes a hydrolysis reaction to obtain the self-assembled monolayer hole transport material based on the polycarbazole derivative shown in Formula I. The reaction formula is as follows: ； R1 and R2 are independently selected from C1-C5 alkyl groups, and X is selected from halogens.

3. The preparation method according to claim 2, characterized in that, R1 and R2 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or n-pentyl; X is selected from F, Cl, Br or I.

4. The preparation method according to claim 2, characterized in that, The molar ratio of the compound of formula II to the compound of formula III in step (1) is 1:1-1.

5.

5. The preparation method according to claim 2, characterized in that, The reaction in step (1) is carried out in the presence of a catalyst, namely cuprous iodide.

6. The preparation method according to claim 2, characterized in that, The reaction in step (1) is carried out in the presence of an alkaline substance selected from potassium carbonate and / or sodium carbonate.

7. The preparation method according to claim 2, characterized in that, The reaction in step (1) is carried out in an organic solvent selected from N,N'-dimethylacetamide; The reaction temperature in step (1) is 160~180℃ and the reaction time is 20~24 h.

8. The preparation method according to claim 2, characterized in that, The hydrolysis reaction described in step (2) is carried out in the presence of trimethylbromosilane; The molar ratio of the trimethylbromosilane to the compound shown in Formula IV is 2:1 to 4:1; The hydrolysis reaction in step (2) is carried out in an organic solvent, which is selected from dichloromethane and / or trichloromethane; The hydrolysis reaction described in step (2) is carried out at room temperature for 12 to 18 hours.

9. A perovskite solar cell, characterized in that, The perovskite solar cell comprises a self-assembled monolayer, wherein the self-assembled monolayer comprises the thiazide derivative self-assembled monolayer hole transport material as described in claim 1.

10. The perovskite solar cell according to claim 9, characterized in that, The perovskite solar cell is an inverted perovskite solar cell, which includes, from top to bottom, a cathode layer, an electron transport layer, a passivation layer, a perovskite light-absorbing layer, a self-assembled monolayer, a hole transport layer, and an anode layer arranged sequentially. The self-assembled monolayer is obtained by coating a solution of the thiazide derivative self-assembled monolayer hole transport material as described in claim 1 onto the surface of the hole transport layer and then performing thermal annealing. The heat annealing temperature is 80~120℃, and the heat annealing time is 5~20 minutes.

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