Preparation method of hole material containing diphosphoric acid and application of hole material in roll-to-roll printed perovskite solar cell

Abstract

The invention discloses a hole transport material and application thereof in a roll-to-roll printed perovskite battery, and belongs to the technical field of photovoltaic materials. The hole transport material provided by the invention comprises a compound with a chemical formula shown as a formula I, wherein X is selected from S, O or Se; in the formula (I), R1 to R2 are respectively and independently selected from one of H, substituted C1-30 alkyl, unsubstituted C1-30 alkyl, substituted C1-30 alkoxy, unsubstituted C1-30 alkoxy, substituted C1-30 alkylthio, unsubstituted C1-30 alkylthio, substituted C6-30 aryl and unsubstituted C6-30 aryl. The hole transport material provided by the invention can effectively improve the hole transport efficiency in a photovoltaic device, thereby improving the photoelectric conversion efficiency and stability of the photovoltaic device. The invention also provides a preparation method of the hole transport material and an application of the hole transport material in a roll-to-roll printed perovskite battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic materials, and particularly to a hole transport material preparation method and application thereof in roll-to-roll printing of perovskite solar cells. BACKGROUND

[0002] Perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field due to their high photoelectric conversion performance, low cost, and easy solution processing, etc. In the past few years, the power conversion efficiency (PCE) of perovskite solar cells has broken through 27%, close to the theoretical limit, showing photoelectric performance comparable to traditional silicon-based solar cells. At the same time, the flexibility, lightness, and low cost of perovskite solar cells make them have great development potential in large-scale applications, wearable electronics, and building integrated photovoltaic systems (BIPV), etc.

[0003] However, although the photoelectric performance of perovskite solar cells has made significant progress in the short term, their stability and long-term reliability are still major challenges to their commercial application. The photo-degradation, poor thermal stability, and uneven contact with the interface layer of perovskite materials lead to performance degradation of the battery. These problems become more prominent in practical applications, especially the phase separation, interfacial reaction, and non-radiative recombination of perovskite materials under long-term light, humidity, high temperature, etc. environment, which seriously affects the photoelectric stability and service life of the battery.

[0004] Self-assembled monolayers (SAMs) technology is an effective interface optimization method. SAMs materials form a uniform film of single molecular thickness on the substrate surface through molecular self-assembly, which can play multiple roles in perovskite solar cells: first, they can provide stable chemical bonding to effectively enhance the stability of the interface layer; second, SAMs can also optimize the electron transport properties of the interface, reduce interface charge recombination, and improve photoelectric conversion efficiency. Diphosphonic acid-anchored self-assembled monolayer materials are considered to be ideal materials for improving the interface performance of perovskite solar cells. The diphosphonic acid group enhances the bonding between the molecules and the substrate surface through synergistic effect. This diphosphonic acid-anchored self-assembled monolayer material not only effectively improves the stability of the interface layer, but also enhances charge transport and reduces interfacial reactions, thereby improving the overall performance and stability of perovskite solar cells.

[0005] As a low-cost, large-scale production method, roll-to-roll (R2R) printing technology has become one of the main ways for industrialization of perovskite solar cells. Through printing on a continuous flexible substrate, roll-to-roll printing technology can realize efficient, low-cost and large-scale production of perovskite solar cell films. In order to further improve the stability and efficiency of the cell, the application of self-assembled monolayer in roll-to-roll printed perovskite solar cells is particularly important, especially the introduction of bisphosphonic acid-anchored self-assembled monolayer material, which can provide a more uniform and stable interface during printing, thereby effectively improving the performance of perovskite solar cells. Research and development of various printing deposition technologies for electron transport layer, perovskite, and hole transport layer, including inkjet printing, blade coating, spray coating, and spray deposition, to develop the most optimized printing deposition process for different material systems. Based on the application of bisphosphonic acid-anchored self-assembled monolayer material in roll-to-roll printed perovskite cells, it has great application prospects in promoting the industrialization of perovskite solar cells, reducing production costs, and improving the stability and efficiency of the cell. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a bisphosphonic acid self-assembled monolayer material that can effectively improve the hole transport efficiency in roll-to-roll flexible photovoltaic devices, thereby improving the photoelectric conversion efficiency and stability thereof.

[0007] The present application also provides a preparation method of the bisphosphonic acid self-assembled monolayer material.

[0008] The present application also provides an application of the bisphosphonic acid self-assembled monolayer material.

[0009] According to an embodiment of the first aspect of the present application, a bisphosphonic acid self-assembled monolayer material is provided, which comprises a compound of the chemical formula as shown in Formula I:

[0010]

[0011] wherein X is selected from O, S or Se;

[0012] R1-R2 are independently selected from H, substituted C 1～30 alkyl, unsubstituted C 1～30 alkyl, substituted C 1～30 alkoxy, unsubstituted C 1～30 alkoxy, substituted C 1～30 alkylthio, unsubstituted C 1～30 alkylthio, substituted C 6～30 aryl and unsubstituted C 6～30 aryl.

[0013] The hole transport material according to the embodiments of the present application has at least the following beneficial effects:

[0014] The hole transport material in the present application has a chemical formula as shown in Formula I, adopts a planar core structure based on double-carbazole and thiophene, double-carbazole and furan, which enables the molecules to form a uniform and compact self-assembled monolayer on the substrate surface. The double-carbazole and thiophene skeleton has strong planarity and large π electron cloud, which enables the molecules to form stable molecular arrangement through π-π stacking interaction. This structure not only helps to improve the self-assembly ability of the molecules on the interface, but also effectively optimizes the charge transport channel between the molecules, and promotes the efficient migration of holes. In particular, the π-π stacking enhances the conductivity of the molecular layer, thereby improving the hole transport efficiency and reducing the energy loss caused by non-radiative recombination. Specifically:

[0015] The hole transport material in the present application is used for the electrode and the perovskite material layer (also referred to as the perovskite photoactive layer) in the roll-to-roll flexible photovoltaic device, especially in the perovskite solar cell. The planar core based on double-carbazole and thiophene introduces two phosphoric acid anchoring groups, which enhances the binding force between the molecules and the substrate. The phosphoric acid group as a strong polar group can form a stable chemical bond with the metal ions or hydroxyl groups on the surface of the metal oxide (such as NiOx, TiO2, etc.), significantly improving the stability and adhesion of the molecules on the substrate. The introduction of double phosphoric acid groups makes the combination between the molecules and the metal oxide more firm, thereby effectively reducing the molecular desorption phenomenon caused by environmental factors (such as humidity and temperature change), further improving the air stability of the material. This enhanced air stability provides a strong guarantee for the long-term use of the perovskite solar cell, avoids the common interface degradation problem, and prolongs the service life of the cell.

[0016] The self-assembled monolayer material of double phosphoric acid in the present application can be applied as HTMs in the roll-to-roll flexible perovskite solar cell and large-area module, which is simple to prepare, low in cost, can passivate the perovskite material layer (has the effect of interface passivation) in the cell or module, helps to improve the efficiency and service life of the cell, optimizes the cell structure, reduces the cost, and realizes industrialization. The hole transport material in the present application is used for photovoltaic devices, and the prepared devices have high Voc, Jsc, FF and PCE, the highest energy conversion efficiency reaches more than 24.80%, and good environmental stability can be obtained, which has great commercial prospect in improving the efficiency and stability of the perovskite solar cell, and reducing the cost thereof.

[0017] According to some embodiments of the present application, in the compound shown in Formula I, R1-R2 are independently selected from H, substituted C 1～6 alkyl, unsubstituted C 1～6 alkyl, substituted C1～6 alkyl, unsubstituted C 1～6 alkyl, substituted C 1～6 alkylthio, unsubstituted C 1～6 alkylthio, substituted C

[0018] According to some embodiments of the present application, in the compound of formula I, R1-R2 are independently selected from at least one of H, methyl, methoxy, methylthio and phenyl.

[0019] Specifically, in the compound of formula I, R1 and R2 can be the same or different.

[0020] According to some embodiments of the present application, the hole transport material comprises at least one of the compounds of formulae I-1 to I-15:

[0021]

[0022]

[0023] According to some embodiments of the present application, the hole transport material can be any color from light yellow to dark brown.

[0024] According to some embodiments of the present application, the hole transport material has an ultraviolet-visible absorption peak at 330-390 nm. For example, it can be about 356 nm, 365 nm, 372 nm or about 383 nm.

[0025] According to some embodiments of the present application, the hole transport material has an ultraviolet-visible absorption shoulder at 390-430 nm. For example, it can be about 385 nm, 400 nm or about 405 nm.

[0026] According to some embodiments of the present application, the hole transport material has an optical band gap of 2.7-3.5 eV. For example, it can be about 3.26 eV, 3.17 eV, 3.24 eV or about 3.35 eV.

[0027] According to some embodiments of the second aspect of the present application, a preparation method of the hole transport material is provided, which comprises the following steps:

[0028] S1. subjecting a compound of formula II to Suzuki coupling reaction with a compound of formula III to obtain a compound of formula IV;

[0029] S2. subjecting the compound of formula IV to ring closure and then alkylation to obtain a compound of formula V;

[0030] S3. The compound shown as formula V is subjected to an Arbuzov reaction with a trialkyl phosphite compound to obtain a compound shown as formula VI;

[0031] S4. The compound shown as formula VI is subjected to a hydrolysis reaction;

[0032]

[0033] wherein X is O, S or Se, R3 and R4 are independently selected from substituted C 1～10 alkyl or unsubstituted C 1～10 alkyl.

[0034] According to the preparation method of the embodiment of the present application, at least the following beneficial effects are achieved:

[0035] Since the preparation method adopts all the technical solutions of the hole transport material in the above embodiments, at least all the beneficial effects brought by the technical solutions of the above embodiments are achieved.

[0036] Further, the preparation method provided by the present application is simple and easy to implement, and the raw materials are cheap and easy to obtain.

[0037] Preferably, in step S1, the Suzuki coupling reaction includes reacting the compound shown as formula II with the compound shown as formula III under the catalysis of a base and a palladium; and / or the base is at least one of potassium carbonate, sodium carbonate, potassium tert-butoxide, sodium tert-butoxide and cesium carbonate; and the palladium catalyst is at least one of tetrakis(triphenylphosphine)palladium, palladium acetate, bis(triphenylphosphine)palladium dichloride, tris(dibenzylideneacetone)dipalladium and tri(o-tolyl)phosphine or cuprous iodide.

[0038] Preferably, in step S2, the ring-closing reaction includes reacting the compound shown as formula IV with triethyl phosphite, and then reacting with dibromobutane in an alkaline environment.

[0039] Preferably, in step S3, the Arbuzov reaction includes reacting the compound shown as formula V with a trialkyl phosphite compound; and / or the trialkyl phosphite compound is at least one of triethyl phosphite, tripropyl phosphite and trimethyl phosphite.

[0040] Preferably, in step S4, the hydrolysis reaction includes reacting the compound shown as formula VI with trimethyl halosilane; and / or the trimethyl halosilane is at least one of trimethylchlorosilane, trimethylbromosilane and trimethyliodosilane.

[0041] Preferably, the molar ratio of the compound of formula II to the compound of formula III is 1:(2-4), the molar ratio of the amount of the base to the compound of formula II is (2-4):1, and the molar ratio of the amount of the catalyst to the compound of formula II is (0.05-0.2):1.

[0042] Preferably, the molar ratio of the compound of formula IV to triethyl phosphite is 1:(5-20).

[0043] Preferably, the molar ratio of the compound of formula IV to dibromobutane is 1:(5-20), and the molar ratio of the compound of formula IV to the base is 1:(3-5).

[0044] Preferably, the molar ratio of the compound of formula V to trialkyl phosphite is 1:(5-20).

[0045] Preferably, the molar ratio of trimethyl halogen silane to the compound of formula VI is (0.5-5):1.

[0046] Preferably, in step S1, the temperature of the Suzuki coupling reaction is 90-110°C; and / or, in step S2, the duration of the reaction is 12-30h.

[0047] Preferably, in step S2, the temperature of the ring-closing reaction is 140-170°C; and / or, in step S2, the duration of the hydrolysis reaction is 12-30h.

[0048] Preferably, in step S3, the temperature of the Arbuzov reaction is 140-170°C; and / or, in step S2, the duration of the hydrolysis reaction is 12-24h.

[0049] Preferably, in step S4, the temperature of the hydrolysis reaction is 15-40°C; and / or, in step S2, the duration of the hydrolysis reaction is 5-30h.

[0050] Since the hole transport layer adopts all the technical solutions of the self-assembled monolayer material of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0051] According to some embodiments of the present application, the hole transport layer is a monolayer. The reason for achieving such an effect is the self-assembly performance of the hole transport material.

[0052] According to some embodiments of the present application, the thickness of the hole transport layer is 5-100nm.

[0053] According to some embodiments of the present application, the thickness of the hole transport layer is 10-20 nm.

[0054] According to embodiments of the fourth aspect of the present application, there is provided a photovoltaic device comprising the hole transport layer; and / or, a raw material for preparing the photovoltaic device comprises the hole transport material.

[0055] As the photovoltaic device adopts all the technical solutions of the hole transport layer or the hole transport material of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0056] According to some embodiments of the present application, the photovoltaic device comprises at least one of a solar cell type device and an organic light emitting diode.

[0057] According to some embodiments of the present application, the solar cell type device comprises at least one of an organic solar cell, a roll-to-roll printed perovskite solar cell, a perovskite solar cell, and a corresponding large-area module thereof.

[0058] According to some embodiments of the present application, the area of the module of the roll-to-roll printed perovskite solar cell is 1-500 cm 2 , for example, specifically 400 cm 2 .

[0059] According to some embodiments of the present application, the roll-to-roll printed perovskite solar cell comprises a flexible substrate, the hole transport layer, a perovskite material layer, an electron transport layer, and a metal electrode layer arranged in a stack. Among them,

[0060] The flexible substrate is polyethylene naphthalate / indium tin oxide or polyethylene terephthalate / indium tin oxide.

[0061] The thickness of the indium tin oxide substrate is 0.5-10 mm, for example, specifically about 1 mm, 1.1 mm, 1.2 mm, or about 1.5 mm.

[0062] The raw material for preparing the hole transport layer is the self-assembled monolayer hole transport material of the bisphosphonic acid. The thickness is 5-50 nm, for example, specifically about 10 nm, 15 nm, or about 20 nm.

[0063] The thickness of the perovskite material layer is 100-1000 nm, for example, specifically about 500 nm, 600 nm, 700 nm, or about 800 nm.

[0064] The electron transport layer comprises a C60 layer and a BCP layer arranged in a stack, the C60 layer being between the perovskite material layer and the BCP layer. The thickness of the electron transport layer is 10-100 nm; for example, it can be specifically 10-50 nm. For example, it can be specifically about 20 nm, 25 nm, or about 30 nm. Among them,

[0065] The thickness of the C60 layer is 10-40 nm; for example, it can be specifically about 15 nm, 20 nm, or about 25 nm.

[0066] The thickness of the BCP layer is 1-10 nm; for example, it can be specifically about 3 nm, 5 nm, or about 8 nm.

[0067] The material of the metal electrode layer comprises at least one of Au, Ag, Al, or Cu.

[0068] The thickness of the metal electrode layer is 50-300 nm. For example, it can be specifically about 70 nm, 80 nm, 90 nm, 100 nm, or about 200 nm.

[0069] According to some embodiments of the present application, the preparation method of the perovskite solar cell comprises coating a slurry containing the hole transport material on the surface of the substrate and annealing to form the hole transport layer.

[0070] According to some embodiments of the present application, the concentration of the slurry containing the hole transport material is 0.5-5 mg / mL. For example, it can be specifically 1-3 mg / mL.

[0071] According to some embodiments of the present application, the annealing temperature is 80-120℃.

[0072] According to some embodiments of the present application, the annealing time is 5-50 min.

[0073] Unless otherwise specified, the terms in the present application are defined as follows:

[0074] “Protective atmosphere” comprises at least one of an inert gas or nitrogen. Among them, the inert gas comprises a group 0 gas.

[0075] “Unsubstituted” means that the H in the corresponding group is not substituted.

[0076] "substituted" means that at least one H can be further replaced by one selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, halo, haloalkyl, haloalkenyl, haloalkynyl, haloaryl, hydroxy, alkoxy, alkenoxy, aryloxy, benzyloxy, haloalkoxy, haloalkenoxy, haloaryloxy, nitro, nitroalkyl, nitroalkenyl, nitroalkynyl, nitroaryl, nitroheterocyclyl, amino, alkylamino, dialkylamino, alkenylamino, alkynylamino, arylamino, diarylamino, phenylamino, diphenylamino, benzylamino, dibenzylamino, hydrazino, acyl, acylamino, diacylamino, acyloxy, heterocyclyl, heterocyclyloxy, heterocyclylamino, haloheterocyclyl, carboxyl ester, carboxyl, carboxyl amide, mercapto, alkylthio, benzylthio, acylthio, and phosphorus-containing groups.

[0077] "alkyl" means a branched or straight-chain saturated aliphatic hydrocarbon group, having the indicated number of carbon atoms.

[0078] "C 1～30 "alkyl" means an alkyl group having a total number of carbon atoms from 1 to 30, including C 1～30 "straight-chain alkyl", C 1～30 "branched-chain alkyl", and C 3～30 "cycloalkyl"; similar explanations apply to "C 1～6 "alkyl" and the like, except that the number of carbon atoms is different.

[0079] "alkoxy" means an alkyl group as defined herein attached through an oxygen atom, i.e., "alkyl-O-". "C 1～30 "alkoxy" means an alkoxy group having a total number of carbon atoms from 1 to 30, including C 1～30 "straight-chain alkoxy", C 1～30 "branched-chain alkoxy", and C 2～30 "cycloalkoxy", e.g., methoxy, ethoxy, n-propoxy, isopropoxy, and the like. Similar explanations apply to "C 1～6 "alkoxy" and the like, except that the number of carbon atoms is different.

[0080] "alkylthio" means an alkyl group as defined herein attached through a sulfur atom, i.e., "alkyl-S-". "C 1～30 "alkylthio" means an alkylthio group having a total number of carbon atoms from 1 to 30, including C 1～30 "straight-chain alkylthio", C 1～30 "branched-chain alkylthio", and C 2～30 "cycloalkylthio", e.g., methylthio, ethylthio, n-propylthio, isopropylthio, and the like. Similar explanations apply to "C 1～6 "alkylthio" and the like, except that the number of carbon atoms is different.

[0081] "C 6～30"Aryl" means a monocyclic or fused polycyclic all-carbon group having a completely conjugated pi-electron system. It refers to a monocyclic or fused polycyclic all-carbon group of from 6 to 30 carbon atoms; for example, benzene, naphthalene, indene, fluorene, and the like.

[0082] Unless otherwise specified, "about" in the present application means the actual meaning is allowed to have an error within the range of ±2%, for example, about 100 actually is 100 ± 2% x 100.

[0083] Unless otherwise specified, "between" in the present application includes the number, for example, "between 2-3" includes the end point values 2 and 3.

[0084] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0085] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0086] Figure 1 is a structural schematic diagram of a flexible perovskite solar cell in the application example 1 of the present application;

[0087] Figure 2 is a nuclear magnetic resonance spectrum of the hole transport material obtained in the example 2 of the present application;

[0088] Figure 3 is an ultraviolet-visible light spectrum curve of the hole transport material obtained in the example 2 of the present application;

[0089] Figure 4 is a J-V curve of a partial perovskite solar cell obtained in the application example 1 of the present application.

[0090] Figure 5 is a J-V curve of a partial perovskite solar cell obtained in the application example 2 of the present application.

[0091] Figure 6 is a J-V curve of a partial perovskite solar cell obtained in the application example 3 of the present application. DETAILED DESCRIPTION

[0092] The concept and the technical effects of the present application will be described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0093] In the description of the application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0094] Unless otherwise specified, the temperature in the specific embodiments is room temperature, i.e. in the range of 20-30°C, and floating within the range does not have a significant impact on the test results.

[0095] Unless otherwise specified in the specific embodiments, the experimental method is generally carried out according to the conventional conditions in the art or according to the conditions recommended by the manufacturer.

[0096] Unless otherwise specified, the raw materials, reagents, etc. used are raw materials and reagents that can be obtained commercially through conventional markets, etc.

[0097] Substrate: purchased from Liaoning Youxuan Technology Co., Ltd., indium tin oxide (ITO) polyethylene terephthalate with a resistance of 15 Ω / sq, including the substrate and the ITO layer provided on the glass surface of the substrate, wherein the thickness of the ITO layer is 150 nm and the thickness of the substrate is 1.1 mm.

[0098] Example 1

[0099] In this example, a hole transport material is prepared, and the specific reaction mechanism is shown in the following formula:

[0100]

[0101] The specific steps are as follows:

[0102] S1. Preparation of the compound shown in formula IV-1: A 100 mL round-bottom flask was charged with the compound shown in formula III-1 (2 g, 4.76 mmol, CAS: 1821662-15-0) and o-bromonitrobenzene (2.4 g, 11.90 mmol, CAS: 577-19-5), K2CO3 (273.2 mg, 1.98 mmol) and Pd(PPh3)4 (80 mg, 0.07 mmol), and 15 mL of toluene / water (5:1; v / v) was injected with a syringe. The reaction was refluxed at 110°C for 24 hours (tracked by TLC plate). The reaction was stopped, extracted with dichloromethane three times, the organic layer was collected and rotary evaporated, purified by column chromatography with petroleum ether:dichloromethane (2:1), rotary evaporated and vacuum dried to obtain a light yellow product (1.54 g, yield 79%).

[0103] S2. Preparation of compound of formula V-1: A 100 mL round bottom flask was charged with compound of formula IV-1 (1.5 g, 3.66 mmol), triethyl phosphite 20 mL, and the reaction was refluxed at 160 °C for 24 h (monitored by TLC plate). The reaction was stopped, methanol was added to the reaction mixture, filtered to obtain the solid which was used directly for the next step. KOH (3.45 g, 62 mmol) was added to the solid, followed by 1,4-dibromobutane (1.85 mL, 15.4 mmol). After the reaction was carried out at 65 °C for 24 h, the reaction was stopped and extracted with dichloromethane, washed with saturated brine for three times, the organic layer was collected and dried over sodium sulfate. The product was purified by column chromatography using petroleum ether:dichloromethane (2:1) as eluent, dried under vacuum to obtain the yellowish product (1.35 g, yield 60%).

[0104] S3. A 100 mL two-necked flask was charged with compound of formula V-1 (1 g, 1.62 mmol) and triethyl phosphite 20 mL under nitrogen atmosphere. The reaction was heated to 165 °C and stirred for 48 h. After the reaction was cooled to room temperature, the solvent was removed by distillation under reduced pressure to obtain the crude product. The crude product was separated by column chromatography using dichloromethane as eluent to obtain the oily liquid product (1.09 g, yield 92%).

[0105] S4. Synthesis of compound of formula I-1: A 100 mL Schlenk flask was charged with compound of formula VI-1 (1 g, 1.37 mmol) and purged with argon for three times. Dichloromethane (40 mL) was added to the flask. Trimethylsilyl bromide (2 mL, 15.16 mmol, CAS: 2857-97-8, abbreviated as BrSiMe3) was added to the flask slowly at room temperature. The reaction was stirred at room temperature for 12 h. The reaction was monitored by TLC and stopped. The reaction mixture was directly dried by vacuum rotary evaporator and recrystallized with 50 mL of dichloromethane and methanol mixture (2:1, V / V) to obtain compound of formula I-1, which appeared as a yellowish powder (0.72 g, yield 85%).

[0106] The compound of formula I-1 was characterized by nuclear magnetic resonance and mass spectrometry, and the data are as follows:

[0107] 1 H NMR (400 MHz, DMF-d7) δ 8.21 (d, J = 7.4 Hz, 4H), 7.93 (s, 2H), 7.76 (d, J = 7.2 Hz, 2H), 7.42 (t, J = 7.6 Hz, 2H), 7.20 (t, J = 7.6 Hz, 2H), 4.79 (d, J = 8.0 Hz, 4H), 1.95 (dd, J = 38.4, 11.3 Hz, 12H).

[0108] HRMS-ESI (m / z): [M+H] + :(C 32 H 32 N2O7P2), m / z: calculate: 618.5625, found: 618.1683.

[0109] Example 2

[0110] In this example, a hole transport material was prepared, and the specific reaction mechanism is shown in the following formula:

[0111]

[0112] S1. Preparation of the compound shown in formula IV-2: A 100 mL round bottom flask was charged with the compound shown in formula III-2 (2 g, 4.58 mmol, CAS: 1378383-16-4) and o-bromonitrobenzene (2.4 g, 11.90 mmol, CAS: 577-19-5), K2CO3 (273.2 mg, 1.98 mmol) and Pd(PPh3)4 (80 mg, 0.07 mmol), and 15 mL of toluene / water (5:1; v / v) was injected with a syringe. The reaction was refluxed at 110°C for 24 h (tracked by TLC plate). The reaction was stopped, extracted with dichloromethane three times, the organic layer was collected and rotary evaporated to dryness, purified by column chromatography using petroleum ether:dichloromethane (2:1), rotary evaporated to dryness, and vacuum dried to obtain the yellowish product (1.46 g, yield 75%).

[0113] S2. Preparation of the compound shown in formula V-2: A 100 mL round bottom flask was charged with the compound shown in formula IV-2 (2 g, 4.69 mmol), and triethyl phosphite 20 mL was added, and the reaction was refluxed at 160°C for 24 h (tracked by TLC plate). The reaction was stopped, precipitated with methanol, filtered, and the obtained solid was directly used in the next step. KOH (3.45 g, 62 mmol) was added, and 1,4-dibromobutane (1.85 mL, 15.4 mmol) was injected. After the reaction was stopped, extracted with dichloromethane, washed with saturated brine three times, the organic layer was collected and rotary evaporated to dryness, purified by column chromatography using petroleum ether:dichloromethane (2:1), rotary evaporated to dryness, and vacuum dried to obtain the yellowish product (1.66 g, yield 56%).

[0114] S3. Under nitrogen protection, a 100 mL two-necked flask was sequentially charged with the compound shown in formula V-2 (1 g, 1.58 mmol) and triethyl phosphite 20 mL. The reaction was heated to 160°C and stirred for 48 h. After the reaction was cooled to room temperature, the solvent was removed by reduced pressure distillation to obtain the crude product. The crude product was separated by column chromatography with dichloromethane as the eluent to obtain the yellow oily product (1.02 g, yield 86%).

[0115] S4. Synthesis of compound of formula I-2: A 100 mL Schlenk flask was charged with compound of formula VI-2 (1 g, 1.34 mmol) and purged with argon for three times, then dichloromethane (40 mL) was injected into the flask. Trimethylsilyl bromide (2 mL, 15.16 mmol, CAS: 2857-97-8, abbreviated as BrSiMe3) was slowly added into the flask at room temperature, and the reaction was stirred at room temperature for 12 h. The reaction was monitored by TLC and stopped when the reaction was completed. The obtained reaction solution was directly dried by a vacuum rotary evaporator, and recrystallized with 50 mL of a mixture of dichloromethane and methanol (2:1, by volume), to obtain the compound of formula I-3, which was shown to be a light yellow powder (0.739 g, yield 87%).

[0116] The compound of formula I-2 was characterized by nuclear magnetic resonance and mass spectrometry, and the statistical results were as follows:

[0117] 1 H NMR (400 MHz, DMF-d7) δ 8.24 (d, J = 7.6 Hz, 4H), 7.98 (s, 2H), 7.76 (d, J = 8.2 Hz, 2H), 7.48 (t, J = 7.6 Hz, 2H), 7.26 (t, J = 7.4 Hz, 2H), 4.73 (d, J = 8.0 Hz, 4H), 1.97 (dd, J = 39.4, 11.3 Hz, 12H).

[0118] HRMS-ESI (m / z): [M+H] + :(C 32 H 32 N2O6P2S), m / z: calculate: 634.6235, found: 634.1338.

[0119] Example 3

[0120] In this example, a hole transport material was prepared, and the specific reaction mechanism is shown in the following formula:

[0121]

[0122] S1. Preparation of compound of formula IV-3: A 100 mL round bottom flask was charged with compound of formula III-3 (2 g, 4.58 mmol, CAS: 1378383-16-4) and o-bromonitrobenzene (2.47 g, 11.90 mmol, CAS: 5326-34-1), K2CO3 (273.2 mg, 1.98 mmol) and Pd(PPh3)4 (80 mg, 0.07 mmol) and 15 mL of toluene / water (5:1; v / v) was injected via syringe. The reaction was refluxed at 110 °C for 24 h (monitored by TLC plate). The reaction was stopped, extracted with dichloromethane, thrice, the organic layer was collected and dried under vacuum, purified using column chromatography with petroleum ether: dichloromethane (2:1) and dried under vacuum to get the pale yellow product (1.49 g, yield 72%).

[0123] S2. Preparation of compound of formula V-3: A 100 mL round bottom flask was charged with compound of formula IV-3 (2 g, 4.41 mmol) and triethyl phosphite 20 mL was added, the reaction was refluxed at 160 °C for 24 h (monitored by TLC plate). The reaction was stopped, precipitated with methanol, filtered and the obtained solid was taken for the next step. KOH (3.45 g, 62 mmol) was added and 1,4-dibromobutane (1.85 mL, 15.4 mmol) was injected. After 24 h of reaction at 65 °C, the reaction was stopped and extracted with dichloromethane, washed with saturated brine, thrice, the organic layer was collected and dried under vacuum, purified using column chromatography with petroleum ether: dichloromethane (2:1) and dried under vacuum to get the pale yellow product (1.77 g, yield 61%).

[0124] S3. To a 100 mL two necked flask was added compound of formula V-3 (1 g, 1.52 mmol) and triethyl phosphite 20 mL was added under nitrogen atmosphere. The reaction was heated to 160 °C and stirred for 48 h. After the reaction was cooled to room temperature, the solvent was removed under reduced pressure to get the crude product. The crude product was separated using column chromatography with dichloromethane as eluent to get the product as yellow oil (1.03 g, yield 91%).

[0125] S4. Synthesis of the compound shown in formula I-3: A 100 mL Schlenk reaction bottle was added with the compound shown in formula VI-1 (1 g, 1.29 mmol) and argon was replaced for three times, then dichloromethane (40 mL) was injected into the reaction bottle. Trimethylsilyl bromide (2 mL, 15.16 mmol, CAS: 2857-97-8, abbreviated as BrSiMe3) was slowly added into the reaction bottle at room temperature, and the reaction was stirred at room temperature for 12 h. The reaction was monitored by TLC, and the reaction was stopped. The obtained reaction solution was directly dried by a vacuum rotary evaporator, and recrystallized with 50 mL of a mixture of dichloromethane and methanol (the volume ratio of dichloromethane to methanol was 2:1), to obtain the compound shown in formula I-3, which was shown as a light yellow powder (1.14 g, yield 89%).

[0126] The compound shown in formula I-2 was characterized by nuclear magnetic resonance and mass spectrometry, and the statistical results were as follows:

[0127] 1 H NMR (400 MHz, DMF-d7) δ 8.21 (d, J = 7.6 Hz, 4H), 7.92 (s, 2H), 7.76 (d, J = 8.2 Hz, 2H), 7.45 (t, J = 7.6 Hz, 2H), 7.23 (t, J = 7.4 Hz, 2H), 4.72 (d, J = 8.0 Hz, 4H), 3.52 (s, 6H), 1.97 (dd, J = 34.4, 11.3 Hz, 12H).

[0128] HRMS-ESI (m / z): [M+H] + :(C 34 H 36 N2O6P2S), m / z: calculate: 662.6775, found: 661.8354.

[0129] Application Example 1

[0130] Reference Figure 1 The example provides a roll-to-roll printed transverse perovskite solar cell. The perovskite solar cell provided in the example includes a substrate (ITO glass, abbreviated as ITO substrate), a hole transport layer (HTM, a monomolecular layer, a thickness of 10 nm), a perovskite material layer (abbreviated as a perovskite layer, a thickness of 700 nm), an electron transport layer (including a C60 layer and a BCP layer, a total thickness of 25 nm) and a metal electrode (Cu, a thickness of 100 nm) which are sequentially stacked. The preparation process includes:

[0131] The ITO flexible substrate (containing ITO coating) was sequentially ultrasonically cleaned with alkaline glass cleaner, deionized water, acetone and isopropanol for 30 min. After nitrogen blowing and drying, the ITO glass was plasma cleaned for 15 min.

[0132] The hole transport layer was prepared using the material obtained in Example 1-3 (Formula I-1, Formula I-2, Formula I-4) as raw material:

[0133] The specific preparation steps of the hole transport layer were as follows: a methanol solution (2 mg / mL) of the hole transport material was spin-coated on the ITO coating surface of the ITO glass at a rotation speed of 4000 rpm, followed by 100°C thermal annealing treatment for 10 min to form the hole transport layer.

[0134] Cs 0.05 (FA 0.9 MA 0.1 ) 0.95 PbI3 perovskite solution was spin-coated on the surface of the hole transport layer material, and 100°C thermal annealing treatment was performed for 30 min. After cooling, the perovskite material layer was formed.

[0135] A 20 nm C60 layer and a 5 nm BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) were respectively evaporated on the surface of the perovskite material layer to form an electron transport layer.

[0136] Finally, a layer of 80 nm Cu was vacuum evaporated on the surface of the electron transport layer as an electrode, thereby completing the preparation of the perovskite solar cell device.

[0137] The effective area of the perovskite solar cell obtained in this example was 7 mm 2 .

[0138] Application Example 2

[0139] This example discloses a large-area roll-to-roll flexible perovskite solar cell module, and finally a perovskite material layer with a thickness of 600 nm is obtained, and the effective area of the device is 400 cm 2 A large-area battery module. The preparation process comprises:

[0140] Substrate cleaning → unwinding → spraying hole layer → printing perovskite layer → spraying electron layer → evaporating back electrode → compounding (encapsulation) → winding → slicing.

[0141] The ITO flexible substrate (containing ITO coating) was sequentially cleaned with alkaline glass cleaner, deionized water, acetone and isopropanol for 30 min. After nitrogen blowing, the ITO glass was subjected to plasma cleaning for 15 min.

[0142] The hole transport layer was prepared using the material obtained in Example 1-3 (Formula I-1, Formula I-2, Formula I-4) as raw material:

[0143] The specific preparation steps of the hole transport layer are as follows: a methanol solution (2 mg / mL) of the hole transport material is sprayed on the ITO coating surface of the ITO flexible substrate, followed by 100°C thermal annealing treatment for 10 min to form the hole transport layer.

[0144] 1.5 mol / L Cs 0.05 (FA 0.9 MA 0.1 ) 0.95 PbI3 perovskite solution is printed on the surface of the hole transport layer material, and 100°C thermal annealing treatment is performed for 30 min. After cooling, the perovskite material layer is formed.

[0145] A 20 nm C60 layer and a 5 nm BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) layer are respectively sprayed on the surface of the perovskite material layer to form an electron transport layer.

[0146] Finally, an 80 nm Cu layer is vacuum evaporated on the surface of the electron transport layer as an electrode, thereby completing the preparation of the perovskite solar cell device.

[0147] The packaging of the perovskite solar cell is an important step to ensure its long-term stability and reliability. A transparent packaging material is coated on the surface of the roll-to-roll flexible perovskite solar cell, and ethylene-vinyl alcohol copolymer (EVA), polyethylene (PE) or other transparent polymers are usually used. These materials can effectively prevent the penetration of water vapor and oxygen, prevent interface oxidation and degradation of the perovskite light absorption layer. After the packaging material is coated, it is heated by a low-temperature curing process (usually between 50-80°C) to form a firm bond between the packaging layer and the perovskite layer.

[0148] Test Example

[0149] The hole transport material obtained in the embodiment, the perovskite solar cell obtained in the application example, and the corresponding module are tested for performance, which specifically includes:

[0150] (1) The optical properties of the hole transport materials obtained in Examples 1-3 are studied by ultraviolet-visible spectroscopy. The ultraviolet-visible spectroscopy test includes: testing a methanol solution (1 g / mL) of the hole transport material, and the measured ultraviolet-visible spectroscopy curve is as follows: Figures 2-3As shown, the absorption peak of the hole transport material obtained in Example 1 is near 329 nm, and the absorption edge is 388 nm; the absorption peak of the hole transport material obtained in Example 2 is near 339 nm, and the absorption edge is 401 nm; the absorption peak of the hole transport material obtained in Example 3 is near 339 nm, and the absorption edge is 413 nm; according to the formula: Egap = 1240 / λ, the optical band gap of the hole transport material obtained in Example 1 is 3.19 eV; the optical band gap of the hole transport material obtained in Example 2 is 3.09 eV, and the optical band gap of the hole transport material obtained in Example 3 is 3.01 eV.

[0151] (2) The electrochemical properties of the hole transport materials obtained in Examples 1-3 were studied by cyclic voltammetry. During the test, the hole transport material was coated on the working electrode, and the cyclic voltammetry test was performed at a scan rate of 10 mV / s with 1 mol / L tetrabutylammonium hexafluorophosphate salt in ethanol as the electrolyte. Ferrocene was used as an external reference;

[0152] The HOMO energy level of the hole transport material obtained in Example 1 was calculated to be -5.24 eV. The HOMO energy level of the hole transport material obtained in Example 2 was -5.34 eV, and the HOMO energy level of the hole transport material obtained in Example 3 was -5.15 eV. The HOMO energy level of the hole transport material obtained in Example 4 was -5.31 eV. The HOMO energy levels of the hole transport materials obtained in Examples 1-3 matched the HOMO energy level of perovskite (-5.48 eV), meeting the working conditions of the hole transport layer in the perovskite solar cell device.

[0153] (3) The open-circuit voltage V 2 , short-circuit current density J oc , fill factor FF and photoelectric energy conversion efficiency PCE of the perovskite solar cell obtained in Application Example 1 were tested under AM1.5G simulated sunlight irradiation with a light source intensity of 100 mW / cm sc , as shown in Figure 4 and Table 1:

[0154] Table 1 Performance results of the perovskite solar cell obtained in Application Example 1

[0155]

[0156]

[0157] According to the above results, the perovskite solar cell using the hole transport material provided by the present application has excellent performance.

[0158] (4)The example also tests the performance of the perovskite solar cell module obtained in example 2, and the open circuit voltage is 40.05V, the short circuit current density is 0.782mA / cm 2 , the fill factor is 65.16%, and the photoelectric energy conversion efficiency is 20.41%.

[0159] In conclusion, the application provides a kind of hole transport material with double phosphoric acid self-assembly forming monolayer, which is a hole transport material with interface passivation, with planar core structure of double carbazole and thiophene, double carbazole and furan, giving the hole transport material high hole transport performance and air stability, and with π-π stacking between monomers, facilitating hole transport.Further, the hole transport material provided by the application provides main transport performance with planar core structure of double carbazole and thiophene, double carbazole and furan, and double phosphonic acid plays an anchoring role, and methyl, methoxy, methylthio and phenyl on the core play a role in adjusting energy level;Based on the fact that double carbazole and thiophene, double carbazole and furan can both play a transport role, it can be reasonably predicted that all the hole transport materials provided by the application have excellent transport role, and are expected to be widely used in photovoltaic devices in combination with suitable perovskite materials.

[0160] The preparation method of the hole transport material provided by the application has simple synthesis steps, mild synthesis conditions, low cost of substrates and catalysts, and simple post-treatment, and the target hole transport material (high target product yield) is obtained in high yield by using simple synthesis and purification processes. The amphiphilic monolayer hole transport material of the synthesized anthracene heterocyclic derivative is used as a self-assembled hole transport material for trans-perovskite solar cells, and a photovoltaic conversion efficiency of 24% or more can be obtained without doping. The hole transport material has interface passivation performance, anchors metal oxides and ITO substrates, can improve the photovoltaic conversion efficiency of the battery while improving the service life of the battery, is suitable for large-area perovskite solar device modules, and can obtain high photovoltaic conversion efficiency. Therefore, the double phosphonic acid self-assembled monolayer as a self-assembled hole transport material for trans-perovskite solar cells promotes charge transport, improves the energy conversion efficiency and stability of the solar cell.

[0161] The embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the application. In addition, the embodiments of the application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A hole transport material, characterized in that The hole transport material includes a compound as shown in Formula I: wherein X is selected from O, S or Se; R1 to R2 are independently selected from H, substituted C 1～30 Alkyl, unsubstituted C 1～30 Alkyl, substituted C 1～30 Alkoxy, unsubstituted C 1～30 Alkoxy, substituted C 1～30 Alkylthio, unsubstituted C 1～30 Alkylthio, substituted C 6～30 Aryl and unsubstituted C 6～30 One of the aromatic groups.

2. The hole transport material according to claim 1, characterized in that In the compound represented by formula I, R1 to R2 are independently selected from H, substituted C 1～6 Alkyl, unsubstituted C 1～6 Alkyl, substituted C 1～6 Alkoxy, unsubstituted C 1～6 Alkoxy, substituted C 1～6 Alkylthio, unsubstituted C 1～6 One of an alkylthio group, a substituted phenyl group and an unsubstituted phenyl group.

3. The hole transport material according to claim 1 or 2, characterized in that The hole transport material includes at least one of the compounds shown in chemical formulas I-1 to I-15:

4. A method for preparing a hole transport material according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: S1. Suzuki coupling reaction of the compound represented by formula II with the compound represented by formula III to obtain a compound represented by formula IV; S2. The compound represented by formula IV is cyclized and then alkylated to obtain the compound represented by formula V; S3. Arbuzov reaction of the compound represented by formula V with a trialkyl phosphite compound to obtain a compound represented by formula VI; S4. The compound represented by formula VI is subjected to a hydrolysis reaction; Wherein, X is O, S or Se, R3 and R4 are independently selected from substituted C 1～10 Alkyl or unsubstituted C 1～10 alkyl.

5. The preparation method according to claim 4, (1) characterized in that: In step S1, the Suzuki coupling reaction comprises reacting the compound represented by formula II with the compound represented by formula III under the catalysis of a base and metal palladium; and / or, the base is at least one of potassium carbonate, sodium carbonate, potassium tert-butoxide, sodium tert-butoxide, and cesium carbonate; and the palladium catalyst is at least one of tetrakistriphenylphosphine palladium, palladium acetate, bis(triphenylphosphine)palladium dichloride, tris(dibenzylideneacetone)dipalladium, and tri(o-tolyl)phosphine. (2) It is characterized in that, in step S2, the ring-closing reaction comprises reacting the compound represented by formula IV with triethyl phosphite; and then reacting with dibromobutane under an alkaline environment. (3) It is characterized in that, in step S3, the Arbuzov reaction comprises reacting the compound represented by formula V with a trialkyl phosphite compound; and / or the trialkyl phosphite compound is selected from at least one of triethyl phosphite compounds, tripropyl phosphite compounds and trimethyl phosphite compounds. (4) It is characterized in that in step S4, the hydrolysis reaction comprises reacting the compound represented by formula VI with trimethylhalosilane; and / or the trimethylhalosilane is selected from at least one of trimethylchlorosilane, trimethylbromosilane and trimethyliodosilane.

6. The preparation method according to claim 5, (1) characterized in that: The molar ratio of the compound represented by formula II to the compound represented by formula III is 1:(2-4); the molar ratio of the amount of the base to the compound represented by formula II is (2-4):1; and the molar ratio of the amount of the catalyst to the compound represented by formula II is (0.05-0.2):

1. (2) It is characterized in that the molar ratio of the compound represented by IV to triethyl phosphite is 1:(5-20). (3) It is characterized in that the molar ratio of the compound represented by IV to dibromobutane is 1:(5-20); the molar ratio of the compound represented by IV to the base is 1:(3-5). (4) It is characterized in that the molar ratio of the compound represented by V to the trialkyl phosphite is 1:(5-20). (5) It is characterized in that the molar ratio of the trimethylhalosilane to the compound represented by formula VI is (0.5-5):

1.

7. The preparation method according to claim 5, (1) characterized in that: In step S1, the temperature of the Suzuki coupling reaction is 90-110° C.; and / or, in step S2, the reaction time is 12-30 h. (2) It is characterized in that, in step S2, the temperature of the ring-closing reaction is 140-170°C; and / or, in step S2, the duration of the hydrolysis reaction is 12-30 hours. (3) It is characterized in that, in step S3, the temperature of the Arbuzov reaction is 140-170°C; and / or, in step S2, the duration of the hydrolysis reaction is 12-24 hours. (4) It is characterized in that, in step S4, the temperature of the hydrolysis reaction is 15 to 40°C; and / or, in step S2, the duration of the hydrolysis reaction is 5 to 30 hours.

8. A hole transport layer, characterized in that The raw materials for preparing the hole transport layer include the hole transport material according to any one of claims 1 to 3.

9. A roll-to-roll flexible photovoltaic device, characterized in that: The photovoltaic device comprises the hole transport layer according to claim 9; and / or, the raw materials for preparing the photovoltaic device comprise the hole transport material according to any one of claims 1 to 3.

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