Perovskite solar cells modified with bisfluorenequinone thiophene derivatives

Abstract

The invention discloses a perovskite solar cell modified by a bisfluorenylquinone thiophene derivative, which is composed of a transparent conductive electrode, an electron transport layer, a perovskite light absorption layer, an interface modification layer, a hole transport layer, and a silver electrode layer arranged in sequence from bottom to top; the material of the perovskite light absorption layer is iodine lead methylammonium; the material of the interface modification layer is a bisfluorenylquinone thiophene derivative; the material of the hole transport layer is 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene. In the present invention, the efficiency of the perovskite solar cell prepared by using the bisfluorenylquinone thiophene derivative as the interface modification layer material is 19.09%, which is 27% higher than the efficiency of the unmodified cell.

Description

Technical Field

[0001] The invention relates to a perovskite solar cell based on interface material modification, in particular to a perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative. Background Art

[0002] At present, the photoelectric conversion efficiency of perovskite solar cells has exceeded 25%, and has great commercial prospects. Perovskite solar cells have some common problems that need to be solved, such as: (1) Most of the widely reported high-efficiency perovskite solar cell devices are prepared in an inert gas environment such as nitrogen (to prevent air or water from entering the battery and degrading the perovskite), and the production cost is relatively high. The efficiency of perovskite solar cell devices prepared under air conditions is still generally low. (2) The chemical and structural stability of perovskite materials is insufficient, which can easily cause device degradation and reduce battery efficiency. Therefore, it is particularly important to make batteries made under atmospheric conditions have both efficiency and stability.

[0003] The general structure of a perovskite solar cell is: conductive electrode substrate / electron transport layer / perovskite layer / hole transport layer / metal electrode. When the battery is working, the perovskite layer absorbs photons and generates excitons, forming electrons and holes, which are injected and transported to the electron transport layer and the hole transport layer, respectively. Among them, modifying the interface between the perovskite layer and the hole transport layer is one of the effective ways to obtain high-performance solar cells. For example, the literature (ACS Appl Mater Inter, 2018, 10 (22): 18787-18795) introduces a polystyrene layer between the perovskite layer and the hole transport layer of a perovskite solar cell; the literature (Appl Surf Sci, 2021, 570, 151259) uses 4-hydroxybenzaldehyde as an interface modification material; Patent (CN105469996) adds a layer of silicon dioxide-coated gold nanoparticles between the hole transport layer and the perovskite layer of the planar heterojunction perovskite solar cell; Patent (CN113644204) adds an amine compound containing a cyclic group between the perovskite layer and the hole transport layer to form an interface modification layer; Patent (CN113725368) uses ammonium nitrate as the interface modification layer between the perovskite layer and the hole transport layer; In addition, diethanolamine, tri-n-octylphosphine oxide, thiophene and pyridine are also commonly used in this field as interface modification layer materials. These methods have played a positive role in improving battery efficiency and stability.

[0004] Bis(fluorenylidene)quinonethiophene is a typical quinone heterocyclic compound with the chemical structure It has the characteristics of rigid molecular structure, plane, and high molar extinction coefficient. Since it was first reported in 1991 (reference: Tetrahedron Lett., 1991, 32, 4313–4316; Tetrahedron Lett., 1991, 32, 4367–4370), it has been studied and applied in organic thin-film solar cells, organic field-effect transistors, dyes, organic synthesis intermediates, etc. In addition, derivatives based on the difluorenylquinone thiophene structure have also been reported. The literature (New J. Chem., 2022, 46, 6729–6737) successfully introduced alkyl, alkoxy or halogen on the thiophene unit. The patent (CN107337662A) introduced 1 to 4 sulfonic acid groups on the difluorenyl structure, making the difluorenylquinone thiophene water-soluble, so it can be used for dyeing textiles. The patent (US20110303909A1) introduces a series of aromatic structural fragments with planar structural characteristics, such as fluorenyl, into the fluorenyl structure, and uses the obtained derivatives as semiconductor materials in the preparation of organic thin film transistors.

[0005] There is no report on the application of derivatives based on the bis(fluorenylidenequinone)thiophene structure in perovskite solar cells. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a perovskite solar cell modified based on a bisfluorenylidenequinone thiophene derivative.

[0007] In order to solve the above technical problems, the present invention provides a perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative, wherein the general structural formula of the bisfluorenylidenequinone thiophene derivative is as follows:

[0008]

[0009] In formula I, R is optionally selected from a hydrogen atom, an alkyl group, an alkoxy group or an aryl group.

[0010] As an improvement of the perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative of the present invention: the bisfluorenylidenequinone thiophene derivative is any of the following:

[0011]

[0012] As a further improvement of the perovskite solar cell modified by a bisfluorenylidenequinone thiophene derivative of the present invention, it is composed of a transparent conductive electrode (transparent conductive glass), an electron transport layer (titanium dioxide electron transport layer), a perovskite light absorption layer, an interface modification layer, a hole transport layer, and a silver electrode layer arranged in sequence from bottom to top;

[0013] The material of the perovskite light-absorbing layer is methylammonium lead iodide (CH3NH3PbI3);

[0014] The material of the interface modification layer is a difluorenylquinone thiophene derivative;

[0015] The material of the hole transport layer is 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD).

[0016] The present invention also provides a method for preparing the above-mentioned perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative, comprising the following steps:

[0017] (1) preparing (spin coating) a titanium dioxide electron transport layer on a transparent conductive electrode substrate;

[0018] (2) Preparing a perovskite light-absorbing layer on the titanium dioxide electron transport layer: dissolving lead diiodide (PbI2) and methylammonium iodide (CH3NH3I) in a mixed solution of DMF and DMSO to form a perovskite precursor solution, which is then spin-coated on the titanium dioxide electron transport layer. In the final stage of spin coating (10 to 15 seconds), ethyl acetate is added dropwise, and annealing is performed to obtain a perovskite light-absorbing layer.

[0019] (3) Spin coating a chlorobenzene solution of a difluorenylquinone thiophene derivative with a concentration of 1 to 10 mg / mL on the perovskite light absorbing layer, and annealing to obtain an interface modification layer; the spin coating speed is 4000±400 rpm; the spin coating time is 30±5 s; the annealing temperature is 80 to 100° C., and the annealing time is 0.5 to 1 h;

[0020] (4) spin coating a Spiro-OMeTAD hole transport layer on the bis(fluorenylidenequinonethiophene) derivative interface layer;

[0021] (5) Attach a top silver electrode to the hole transport layer.

[0022] Note: Except step (3), all other steps are conventional methods.

[0023] As an improvement of the method for preparing the perovskite solar cell of the present invention: the method for preparing the bisfluorenylidenequinone thiophene derivative comprises the following steps:

[0024] ① Compound 1 and compound 2 are subjected to Suzuki coupling reaction to obtain compound 3;

[0025] Compound 1 is: Compound 2 is

[0026] (2) reacting compound 3 with 2,5-dilithiothiophene to obtain compound 4;

[0027] Compound 3 is: Compound 4 is

[0028] (3) subjecting compound 4 to a dehydroxylation-rearrangement reaction to obtain a bisfluorenylidenequinone thiophene derivative;

[0029]

[0030] Here, R is optionally selected from a hydrogen atom, an alkyl group, an alkoxy group or an aryl group.

[0031] As an improvement of the method for making a perovskite solar cell of the present invention:

[0032] The Suzuki coupling reaction of step ① is as follows: under the protection of inert gas, in a mixed system consisting of organic solvent I and water, compound 1 and compound 2, potassium carbonate are reacted under the catalysis of tetrakis(triphenylphosphine)palladium reagent, the molar ratio of compound 1 to compound 2 is 1:3; the molar ratio of potassium carbonate: compound 2=1:1; the molar ratio of tetrakis(triphenylphosphine)palladium reagent to compound 1 is 0.02-0.025:1; the coupling reaction temperature is 65±5°C; the reaction time is until the detection compound 1 is completely consumed (the reaction time is about 16±1 hours);

[0033] The reaction product was post-treated (including extraction and silica gel column chromatography separation) to obtain compound 3;

[0034] Step ② is: under the protection of inert gas, compound 3 is added to a tetrahydrofuran solution of 2,5-dilithiothiophene stored at -78°C, wherein the molar ratio of compound 3 to 2,5-dilithiothiophene is 2.5:1; the reaction system is naturally heated to room temperature and then the reaction is continued for 4±0.5 hours; the reaction product is post-treated (including extraction and silica gel column chromatography separation) to obtain compound 4;

[0035] The room temperature refers to 25±5°C;

[0036] The dehydroxylation-rearrangement reaction of step ③ comprises the following steps: under the protection of inert gas, in an organic solvent II, reacting compound 4 with tin dichloride; the molar ratio of compound 4 to tin dichloride is 1:5; the reaction temperature is room temperature (room temperature refers to 25±5°C); the reaction time is until the detection compound 4 is completely consumed (the reaction time is about 8±1 hours); the reaction product is post-treated (including extraction and silica gel column chromatography separation) to obtain a bis(fluorenylidenequinone) thiophene derivative (Formula I).

[0037] As a further improvement of the method for making a perovskite solar cell of the present invention:

[0038] In the step ①, the organic solvent I is tetrahydrofuran; the volume ratio of tetrahydrofuran to water is 10:1; 30±5 ml of tetrahydrofuran is used for every 2.0 mmol of compound 1;

[0039] In step ②: the tetrahydrofuran solution of 2,5-dilithiothiophene is prepared by reacting 2,5-dibromothiophene with n-butyl lithium in tetrahydrofuran (stored at -78°C); the molar ratio of 2,5-dibromothiophene to n-butyl lithium is 1:2.5; 5±0.5 mL of tetrahydrofuran is used for every 0.8 mmol of 2,5-dibromothiophene; the reaction temperature is -78°C; and the reaction time is 0.5 to 1 h;

[0040] In the step ③: the organic solvent II is chloroform; 4±0.5 mL of tetrahydrofuran is used for every 0.2 mmol of compound 4.

[0041] The beneficial effects of the present invention are:

[0042] (1) The present invention uses difluorenylidenequinone thiophene as the parent skeleton and uses triphenylamine to modify its structure to obtain a new difluorenylidenequinone thiophene derivative, which has a good effect of passivating the defects of perovskite in perovskite solar cells. In the present invention, the efficiency of the perovskite solar cell prepared by using the difluorenylidenequinone thiophene derivative as the interface modification layer material is 19.09%, which is 27% higher than the efficiency of the unmodified cell.

[0043] (2) After being exposed to 85% humidity and room temperature (25±5°C) for 500 hours, the perovskite solar cell of the present invention still retains 70% to 80% of the initial efficiency, indicating that the perovskite solar cell modified with the difluorenylquinone thiophene derivative of the present invention has good stability.

[0044] (3) The perovskite solar cell modified with a bis(fluorenylidenequinone) thiophene derivative of the present invention can be prepared in an air atmosphere without the need for inert gas protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0046] Figure 1 For compound Ia 1 H NMR spectrum.

[0047] Figure 2 For compound 4a 1 H NMR spectrum.

[0048] Figure 3 For compound 4a 13 C NMR spectrum.

[0049] Figure 4 For compound 3a 1 H NMR spectrum.

[0050] Figure 5 For compound 3a 13 C NMR spectrum.

[0051] Figure 6 For compound Ib 1 H NMR spectrum.

[0052] Figure 7 For compound 4b 1 H NMR spectrum.

[0053] Figure 8 For compound 4b 13 C NMR spectrum.

[0054] Fig. 9 For compound 3b 1 H NMR spectrum.

[0055] Fig.10 For compound 3b 13 C NMR spectrum.

[0056] Fig.11 Visible light absorption spectra of compounds Ia and Ib.

[0057] Fig.12 Schematic diagram of the structure of a perovskite solar cell using compound Ia or Ib as the interface material layer.

[0058] Fig.13 JV curve of perovskite solar cell with compound Ia or Ib as interface material layer.

[0059] Fig.14 The graph shows the change of the relative value of the photoelectric conversion efficiency (relative to the initial efficiency) of the perovskite solar cells in Example 1, Example 2 and the comparative example as a function of the exposure time. DETAILED DESCRIPTION

[0060] The present invention and the method of the present invention are further described below with reference to the examples. These examples are only for further illustrating the present invention and are not intended to limit the protection of the present invention to these examples. Unless otherwise specified, the raw materials or reagents described in the present invention are all commercially available. The transparent conductive electrode substrate is selected from commercially available FTO conductive glass.

[0061] Example 1: Preparation of bis(fluorenylidenequinone) thiophene derivative Ia, by sequentially carrying out the following steps:

[0062] 1): Synthesis of compound 3a

[0063]

[0064] Under nitrogen protection, tetrahydrofuran (30 mL) and deionized water (3 mL) were injected into a 100 mL three-necked flask containing compound 1 (2,7-dibromo-9-fluorenone, 2.0 mmol, 676 mg), compound 2a (4-boric acid triphenylamine, 6 mmol, 1.73 g), tetrakis(triphenylphosphine)palladium (0.044 mmol, 51 mg) and potassium carbonate (6 mmol, 829.2 mg) using a syringe, and then the flask was placed in an oil bath at 65 ° C. and stirred for 16 hours. The compound 1 was completely consumed at this time by thin layer chromatography. The reaction system was naturally cooled to room temperature, water (50 mL) was added, and it was extracted with ethyl acetate (50 mL × 3 times), the organic phases were combined, and dried with anhydrous sodium sulfate. After removing the organic solvent (ethyl acetate, tetrahydrofuran) using a rotary evaporator (35 ° C, 0.005 MPa), the residue was separated by silica gel column chromatography (V 石油醚 :V 二氯甲烷 =15:1) to obtain the target compound 3a as a red solid with a yield of 1.06 g and a yield of 80%.

[0065] 1 H NMR (CDCl3, 400MHz) δ7.89 (s, 2H), 7.70 (d, J = 8.0Hz, 2H), 7.55 (d, J = 8.0Hz, 2H), 7.50 (d, J = 8.8Hz, 4H), 7.29 (dd, J 1 =8.0Hz,J 2 =7.6Hz,8H),7.14(d,J=8.4Hz,12H),7.06(dd,J 1 =7.2Hz,J 2 =7.6Hz,4H). 13 C NMR (CDCl3, 100MHz) δ194.00,147.86,147.55,142.67,141.58,135.30,133.45,132. 62,129.40,127.47,124.72,123.56,123.27,122.48,120.70.HRMS(APCI,m / z)calcd for C 49 H 35 N2O:[M+H] + ,667.2749,found:667.2738.

[0066] 2): Synthesis of compound 4a

[0067]

[0068] Under nitrogen protection and -78°C, a 50mL three-necked flask containing 2,5-dibromothiophene (0.8mmol, 90uL) and tetrahydrofuran (5mL) was dripped with a syringe over 5 minutes in n-butyllithium (2mmol) in n-hexane solution (1.25mL). Subsequently, the mixture was stirred at -78°C for 1 hour to obtain a tetrahydrofuran solution containing 2,5-dilithiothiophene (0.8mmol), which was then stored at -78°C.

[0069] Note: The by-product obtained from the above reaction is butyl bromide, which has low activity and does not affect the next reaction. In addition, there is an excess of n-butyl lithium in the system to ensure the complete reaction of 2,5-dibromothiophene, and the small amount of residual n-butyl lithium will not significantly affect the next reaction. Therefore, since the above by-products and residues do not affect the next reaction, there is no need to separate them, and the reaction product can be directly used for subsequent reactions.

[0070] After dissolving compound 3a (2.0mmol, 1.33g) in tetrahydrofuran (5mL), the above tetrahydrofuran solution of 2,5-dilithiothiophene under nitrogen protection was added dropwise with a syringe within 10min. The reaction system was then naturally heated to room temperature under nitrogen protection, and the reaction was continued for 4 hours after heating to room temperature. After the reaction was completed, water (20mL) was added, extracted with ethyl acetate (50mL×3 times), the organic phases were combined, and dried with anhydrous sodium sulfate. After removing the organic solvent using a rotary evaporator (35°C, 0.005MPa), the residue was separated by silica gel column chromatography (V 石油醚 :V 二氯甲烷 =10:1) to obtain the target compound 4a as a light yellow solid with a yield of 284 mg and a yield of 25%.

[0071] 1 H NMR (CDCl3, 400MHz) δ7.78 (s, 4H), 7.66 (d, J = 7.6Hz, 4H), 7.58 (d, J = 8.0Hz, 4H), 7.45 (d, J = 8.4Hz, 8H), 7.24 (dd, J 1 =J 2 =7.6Hz,16H),7.11~6.98(m,32H),6.49(s,2H). 13C NMR(CDCl3,100MHz)δ149.77,147.63,147.35,147.14,140.82,137.59,134.62,129.30,127 .92,127.74,124.75,124.47,123.89,123.13,122.98,120.49,82.34.HRMS(APCI,m / z)calcd for C 102 H 72 N4O2S:[M] + ,1417.5410,found:1417.5389.

[0072] 3): Synthesis of compound Ia

[0073]

[0074] Under nitrogen and room temperature, tin dichloride (1 mmol, 186 mg) was added to a three-necked flask containing compound 4a (0.2 mmol, 283 mg) and chloroform (4 ml), followed by stirring at room temperature for 8 hours. At this time, compound 4a was completely consumed as detected by thin layer chromatography, water (20 mL) was added, and the mixture was extracted with dichloromethane (50 mL × 3 times). The organic phases were combined and dried over anhydrous sodium sulfate. The organic solvent was removed using a rotary evaporator (35 ° C, 0.005 MPa), and the residue was separated by silica gel column chromatography (V 石油醚 :V 二氯甲烷 =10:1) to obtain the target compound Ia as a purple solid with a yield of 132 mg and a yield of 48%.

[0075] Mp:330-332℃. 1 H NMR (CDCl3, 400MHz) δ8.49 (s, 2H), 8.28 (s, 2H), 8.15 (s, 2H), 7.78 (d, J = 8.0Hz, 4H), 7.56 (d, J 1 =8.8Hz,J 2 =9.2Hz,8H),7.44(d,J=7.6Hz,4H),7.34(dd,J 1 =7.6Hz,J 2 =7.2Hz,8H),7.21~7.05(m,16H),7.13~7.00(m,20H),6.83(d,J=8.0Hz,4H).No 13 C NMR spectrum because of its low solubility.HRMS(APCI,m / z)calcd for C 102 H70 N4S:[M] + ,1383.5355,found:1383.5347.

[0076] Example 2: Preparation of bisfluorenylidenequinone thiophene derivative Ib, by sequentially carrying out the following steps:

[0077] 1) Synthesis of compound 3b

[0078]

[0079] Under nitrogen protection, tetrahydrofuran (30 mL) and deionized water (3 mL) were injected into a 100 mL three-necked flask containing compound 1 (2.0 mmol, 676 mg), compound 2b ((4-(di(4-methoxyphenyl)amino)phenyl)boric acid, 6 mmol, 2.10 g), tetrakis(triphenylphosphine)palladium (0.044 mmol, 51 mg) and potassium carbonate (6 mmol, 829.2 mg) using a syringe, and then the flask was placed in an oil bath at 65 ° C. and stirred for 16 hours. After the complete consumption of compound 1 was detected by thin layer chromatography, the reaction system was naturally cooled to room temperature, water (50 mL) was added, and it was extracted with ethyl acetate (50 mL×3 times), the organic phases were combined, and dried with anhydrous sodium sulfate. After removing the organic solvent using a rotary evaporator (35 ° C, 0.005 MPa), the residue was separated by silica gel column chromatography (V 石油醚 :V 乙酸乙酯 =20:1) to obtain the target compound 3b as a red solid with a yield of 1.20 g and a yield of 76%.

[0080] 1 H NMR (CDCl3, 400MHz) δ7.85 (s, 2H), 7.66 (d, J = 8.0Hz, 2H), 7.51 (d, J = 8.0Hz, 2H), 7.44 (d, J = 8 .0Hz,4H),7.10(d,J=8.8Hz,8H),6.99(d,J=8.8Hz,4H),6.86(d,J=8.8Hz,8H),3.81(s,12H). 13 C NMR(CDCl3,100MHz)δ194.20,156.12,148.73,142.40,141.64,140.67,135.25,132.33, 131.41,127.21,126.84,122.23,120.58,120.39,114.82,55.55.HRMS(APCI,m / z)calcd for C 53 H 43 N2O5:[M+H] +,787.3172,found:787.3151.

[0081] 2): Synthesis of compound 4b

[0082]

[0083] Under nitrogen protection and -78°C, a syringe was used to drop a n-hexane solution (1.25 mL) of n-butyl lithium (2 mmol) into a 50 mL three-necked flask containing 2,5-dibromothiophene (0.8 mmol, 90 uL) and tetrahydrofuran (5 mL). Subsequently, the mixture was stirred at -78°C for 1 hour to obtain a tetrahydrofuran solution containing 2,5-dilithiothiophene, which was then stored at -78°C.

[0084] After dissolving compound 3b (2.0mmol, 1.57g) in tetrahydrofuran (5mL), the above tetrahydrofuran solution of 2,5-dilithiothiophene under nitrogen protection was added dropwise with a syringe within 10min. The reaction system was then naturally heated to room temperature under nitrogen protection, and the reaction was continued for 4 hours after heating to room temperature. After the reaction was completed, water (20mL) was added, extracted with ethyl acetate (50mL×3 times), the organic phases were combined, and dried with anhydrous sodium sulfate. After removing the organic solvent using a rotary evaporator (35°C, 0.005MPa), the residue was separated by silica gel column chromatography (V 石油醚 :V 二氯甲烷 =15:1) to obtain the target compound 4b as a light yellow solid with a yield of 306 mg and a yield of 23%.

[0085] 1 H NMR(CDCl3,400MHz)δ7.75(s,4H),7.63(d,J=8.0Hz,4H),7.54(d,J=8.0Hz,4H),7.39(d,J=8.0Hz,8H ),7.05(d,J=8.0Hz,16H),6.92(d,J=8.0Hz,8H),6.81(d,J=8.0Hz,16H),6.43(s,2H),3.78(s,24H). 13 C NMR(CDCl3,100MHz)δ155.86,149.69,148.22,147.30,140.84,137.37,132.69,127.60,127 .50,126.54,123.88,122.95,120.91,120.35,114.75,83.33,53.45.HRMS(APCI,m / z)calcd for C 110 H 88 N4O 10 S:[M]+ ,1657.6255,found:1657.6263.

[0086] 3): Synthesis of compound Ib

[0087]

[0088] Under nitrogen and room temperature, tin dichloride (1 mmol, 186 mg) was added to a three-necked flask containing compound 4b (0.2 mmol, 332 mg) and chloroform (4 ml), and then stirred at room temperature for 8 hours. After the compound 4b was completely consumed by thin layer chromatography, water (20 mL) was added, and it was extracted with dichloromethane (50 mL × 3 times), the organic phases were combined and dried with anhydrous sodium sulfate, and the organic solvent was removed by a rotary evaporator (35 ° C, 0.005 MPa), and the residue was separated by silica gel column chromatography (V 石油醚 :V 二氯甲烷 =10:1) to obtain the target compound Ib, a purple solid, with a yield of 162 mg and a yield of 50%. Mp: 281-283°C. 1 H NMR(CDCl3,400MHz)δ8.47(s,2H),8.23(s,2H),8.10(s,2H),7.72(d,J=8.0Hz,4H),7.52~7.47(m,8H),7.38(d,J=8.8Hz,4H),7.11(d,J=8.8Hz,8H ),7.03(d,J=8.8Hz,4H),6.99(d,J=9.2Hz,8H),6.87(d,J=9.2Hz,8H),6. 72(d,J=8.8Hz,8H),6.66(d,J=8.8Hz,4H),3.82(s,12H),3.75(s,12H).No 13 C NMR spectrum because of its lowsolubility.HRMS(APCI,m / z)calcd for C 110 H 86 N4O8S:[M] + ,1623.6200,found:1623.6161.

[0089] Material properties

[0090] Property 1: Visible light absorption spectra of compounds Ia and Ib.

[0091] Fig.11 The visible light absorption spectra of compounds Ia and Ib are given. The maximum absorption wavelength of compounds Ia and Ib is 558nm.

[0092] Property 2: Electrochemical properties of compounds Ia and Ib.

[0093] The cyclic voltammetry test was carried out on a computer-controlled CHI E660 electrochemical workstation using a traditional three-electrode test system, with a glassy carbon electrode as the working electrode, a platinum electrode as the counter electrode, and an Ag / Ag + The electrode is the reference electrode. The sample is dissolved in anhydrous dichloromethane (10 -3 mol / L), Bu4NPF6 (0.1mol / L) as supporting electrolyte; scanning speed 50mV / s, ferrocene as reference, the energy level of ferrocene under vacuum conditions is -4.8eV. HOMO energy level (E HOMO ) and LUMO energy level (E LUMO ) is calculated according to the following energy level formula:

[0094] E HOMO =-[E ox -E Fc / Fc+ +4.8]eV;

[0095] E LUMO =-[E red -E Fc / Fc+ +4.8]eV;

[0096] Among them, E ox is the half-wave oxidation potential of the substance, E red is the half-wave reduction potential of the substance, E Fc / Fc+ is the half-wave oxidation potential of ferrocene relative to the reference electrode in the test system.

[0097] After testing and calculation, the HOMO energy level of compound Ia is -5.19 eV, and the LUMO energy level is -3.30 eV.

[0098] The HOMO energy level of compound Ib is -5.01 eV, and the LUMO energy level is -3.37 eV.

[0099] The electrochemical energy level band gap of the compound is calculated according to the following energy level formula:

[0100] E Bandgap =E LUMO -E HOMO

[0101] According to the formula, the electrochemical energy level band gaps of compounds Ia and Ib are calculated to be 1.89 eV and 1.64 eV, respectively.

[0102] Example 1: Preparation of perovskite solar cells using compound Ia as interface modification layer material

[0103] Fig.12A schematic diagram of the structure of a perovskite solar cell prepared using compounds Ia and Ib as the interface material layer is given.

[0104] like Fig.12 As shown, the preparation method of the perovskite solar cell using compound Ia as the interface modification layer material is as follows (device production environment: air atmosphere, room temperature, relative humidity of 50%):

[0105] (1) Cleaning FTO conductive glass:

[0106] A square FTO glass with a side length of 1 cm was immersed in acetone, anhydrous ethanol and isopropanol for ultrasonic treatment for 15 minutes each, and then cleaned with an ultraviolet cleaning machine (model BZS250GF-TC, built-in power of 250W, UV lamp with wavelengths of 254nm and 185nm) for 15 minutes. The cleaned FTO glass was used as conductive glass;

[0107] (2) Spin coating titanium dioxide layer:

[0108] Dissolving diisopropoxy diacetylacetonate titanium in anhydrous ethanol to form a low-concentration titanium dioxide precursor solution of 70 mg / mL and a high-concentration titanium dioxide precursor solution of 150 mg / mL respectively;

[0109] Take 0.4 mL of low-concentration titanium dioxide precursor solution and spin-coat it on the conductive glass (cleaned FTO glass) obtained in step (1) at a speed of 2000 rpm for 20 seconds, then place it on a heating table and heat it at 150°C for 30 minutes. After cooling to room temperature, take 0.4 mL of high-concentration precursor solution and spin-coat it again on the coating formed by the low-concentration titanium dioxide precursor solution at a speed of 4000 rpm for 20 seconds. Then place the FTO glass on a heating table and heat it to 450°C at a speed of 2°C / min for annealing, and continue annealing at this temperature for 30 minutes. Thus, a titanium dioxide layer is formed on the conductive glass.

[0110] (3) Spin coating perovskite layer (perovskite light absorbing layer):

[0111] Lead diiodide (PbI2, 461 mg) and methylammonium iodide (CH3NH3I, 159 mg) were added to a mixed solvent of DMF (0.60 mL) and DMSO (0.08 mL) and stirred at room temperature for 0.5 h to prepare a transparent light yellow perovskite (i.e., iodine lead methylammonium) precursor solution. Take 0.08 mL of the perovskite precursor solution and spin-coat it on the titanium dioxide layer, first at a speed of 2000 rpm for 10 seconds and then at a speed of 4000 rpm for 25 seconds. In the last 15 seconds (i.e., after spinning at a speed of 4000 rpm for 10 seconds), ethyl acetate (0.245 mL) was transferred to the coating as an anti-solvent for spin coating. Then annealed at 100°C for 30 minutes and cooled to room temperature. Thus, a perovskite layer (perovskite light-absorbing layer) is formed on the titanium dioxide layer. The material of the perovskite light-absorbing layer is iodine lead methylammonium (CH3NH3PbI3).

[0112] (4) Spin coating interface modification layer:

[0113] Compound Ia was dissolved in chlorobenzene to prepare a solution with a concentration of 2 mg / mL, 0.15 mL of the solution was spin-coated at a speed of 4000 rpm for 30 seconds, and then annealed at 80° C. for 1 hour, thereby forming an interface modification layer on the perovskite layer.

[0114] (5) Spin coating hole transport layer:

[0115] 72.3 mg Spiro-OMeTAD powder, concentration 520 mg mL -1 17.5 μL of acetonitrile solution of lithium bis(trifluoromethane)sulfonamide (Li-TFSI), 29 μL of 4-tert-butylpyridine (4-TBP) and 1 mL of chlorobenzene were uniformly mixed to obtain a chlorobenzene solution of Spiro-OMeTAD.

[0116] The chlorobenzene solution of Spiro-OMeTAD was spin-coated on the interface modification layer at a speed of 4000 rpm for 30 seconds, thereby forming a hole transport layer on the interface modification layer.

[0117] (6) Making the top silver electrode:

[0118] Finally, a 80 nm thick silver electrode layer was formed on the hole transport layer as a top electrode by thermal evaporation deposition (1050-1060°C); a perovskite solar cell modified with a bis(fluorenylidenequinone) thiophene derivative was obtained.

[0119] Example 2: Preparation of perovskite solar cells using compound Ib as interface modification layer material

[0120] Compound Ia was replaced by Compound Ib, and the rest was the same as Example 1.

[0121] Blank comparison example: perovskite solar cell without interface modification layer.

[0122] The step (4) is not performed, that is, the interface modification layer is not spin-coated, so that the hole transport layer is directly formed on the perovskite layer; the rest is the same as in Example 1.

[0123] Implementation Effect

[0124] A digital source meter (Keithley 2400-SCS) was used to measure the intensity of the light under simulated sunlight (AM1.5, 100 mW cm -2 ) The solar cells obtained in the above-mentioned Example 1, Example 2 and the blank comparative example were tested for the current density-voltage characteristic curve to obtain the short-circuit current (J sc , the maximum photocurrent when the circuit is in a short circuit), the open circuit voltage (V oc , the maximum photovoltage when the circuit is off) and fill factor (FF, the cell has a maximum output power (P opt ),the current (J opt ) and voltage (V opt ) multiplied by the short-circuit photocurrent (J sc ) and open circuit photovoltage (V oc ) product ratio) and other performance data.

[0125] The photoelectric conversion efficiency of the battery (i.e. the maximum output power of the battery (P opt ) and input optical power (P in ) is calculated as follows:

[0126] PCE=P opt / P in =(FF×J sc ×V oc ) / P in

[0127] The results are as follows:

[0128] Fig.13 The JV curves of the perovskite solar cell devices prepared with compounds Ia and Ib are given. The present invention uses compounds Ia and Ib as interface material layers to prepare multiple perovskite solar cell devices. Compared with the conventional perovskite solar cell in the comparative example (photoelectric conversion efficiency PCE: 15.02%, open circuit voltage V oc :1.04V, short circuit current J sc :22.22mA cm -2 Compared with the perovskite solar cell prepared by using compound Ia in Example 1, the performance is significantly improved (PCE: 18.13%, V oc :1.06V,J sc:22.34mA cm -2 , FF: 76.59%), the performance of the perovskite solar cell prepared by compound Ib in Example 2 was further improved (PCE: 19.09%, V oc :1.09V,J sc :22.84mA cm -2 , FF: 76.68%). That is, when the bisfluorenylidenequinone thiophene derivative is used as the material of the interface modification layer in the present invention, the open circuit voltage, short circuit current and fill factor of the battery can be significantly improved, and finally the photoelectric conversion efficiency of the battery can be improved.

[0129] Fig.14 The stability performance of the cells prepared in Example 1, Example 2 and the comparative example is given. After the perovskite solar cells were exposed to 85% humidity and room temperature (25±5°C) for 500 hours, the perovskite solar cells of Example 1 and Example 2 still retained 70% and 80% of the initial efficiency, while the photoelectric conversion efficiency of the cells of the comparative example was only 30% of the initial efficiency after 500 hours of exposure. This result shows that when the difluorenylquinone thiophene derivative is used as the material of the interface modification layer in the present invention, the stability of the perovskite solar cell can be significantly improved.

[0130] Comparative Example 1: Preparation of a perovskite solar cell using bis(fluorenylidenequinonethiophene) (Compound 5) as the interface modification layer material:

[0131] That is, compound Ia was replaced by bisfluorenylidenequinothiophene, and the rest was the same as in Example 1.

[0132]

[0133] Comparative Example 2: Compound 6 was synthesized according to the literature (New J. Chem., 2022, 46, 6729-6737), and compound 6 was used as an interface modification layer material to prepare a perovskite solar cell:

[0134]

[0135] That is, compound Ia was replaced by compound 6, and the rest was the same as Example 1.

[0136] Comparative Example 3: Compound 7 was synthesized according to the method of patent (US20110303909A1), and compound 7 was used as the interface modification layer material to prepare a perovskite solar cell: that is, compound Ia was replaced by compound 7, and the rest was the same as Example 1.

[0137]

[0138] The solar cells obtained in Comparative Examples 1 to 3 were tested according to the above method, and the results were as follows:

[0139] Comparative Example 1 (PCE: 9.45%, V oc :1.02V,J sc :18.44mA cm -2 , FF: 58.09%) may be due to the fact that the difluorenylidenequinonethiophene (compound 5) is not modified and its poor solubility leads to uneven coating, thus affecting the effective charge transfer and making the final battery photoelectric conversion efficiency very low.

[0140] Comparative Example 2 (PCE: 15.17%, V oc :1.01V,J sc :21.07mA cm -2 , FF: 71.72%) and Comparative Example 3 (PCE: 13.01%, V oc :0.98V,J sc :19.10mA cm -2 , FF: 69.58%) has an additional alkoxy group in its structure. Although the good solubility of compounds 6 and 7 makes it more convenient to prepare the coating, the battery performance is much lower than that of the battery provided by the present invention, possibly due to the low energy level matching or the poor binding ability of compound 6 with perovskite.

[0141] The above results indicate that the targeted structural modification of the present invention by introducing a triphenylamine derivative structure into the bis(fluorenylidenequinonethiophene) can achieve the best performance of the manufactured battery.

[0142] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative, characterized in that: The bisfluorenylidenequinone thiophene derivative is any one of the following:

2. The perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative according to claim 1, characterized in that: It consists of a transparent conductive electrode, an electron transport layer, a perovskite light absorption layer, an interface modification layer, a hole transport layer, and a silver electrode layer arranged in order from bottom to top; The material of the perovskite light-absorbing layer is lead methylammonium iodide; The material of the interface modification layer is a difluorenylquinone thiophene derivative; The material of the hole transport layer is 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene.

3. The method for preparing a perovskite solar cell modified with a bisfluorenylidenequinone thiophene derivative according to claim 1 or 2, characterized in that The following steps are included: (1) preparing a titanium dioxide electron transport layer on a transparent conductive electrode substrate; (2) Preparing a perovskite light-absorbing layer on the titanium dioxide electron transport layer: dissolving lead diiodide and methylammonium iodide in a mixed solution of DMF and DMSO to form a perovskite precursor solution, spin coating the solution on the titanium dioxide electron transport layer, adding ethyl acetate dropwise at the last stage of spin coating, and annealing to obtain a perovskite light-absorbing layer; (3) Spin coating a chlorobenzene solution of a difluorenylquinone thiophene derivative with a concentration of 1 to 10 mg / mL on the perovskite light absorbing layer, and annealing to obtain an interface modification layer; the spin coating speed is 4000±400 rpm; the spin coating time is 30±5 s; the annealing temperature is 80 to 100° C., and the annealing time is 0.5 to 1 h; (4) spin coating a Spiro-OMeTAD hole transport layer on the bis(fluorenylidenequinonethiophene) derivative interface layer; (5) Attach a top silver electrode to the hole transport layer.

4. The method for manufacturing a perovskite solar cell according to claim 3, characterized in that: The preparation method of the bisfluorenylidenequinone thiophene derivative comprises the following steps: ① Compound 1 and compound 2 are subjected to Suzuki coupling reaction to obtain compound 3; Compound 1 is: Compound 2 is (2) reacting compound 3 with 2,5-dilithiothiophene to obtain compound 4; Compound 3 is: Compound 4 is (3) subjecting compound 4 to a dehydroxylation-rearrangement reaction to obtain a bisfluorenylidenequinone thiophene derivative; R is optionally selected from a hydrogen atom, an alkyl group, an alkoxy group or an aryl group.

5. The method for manufacturing a perovskite solar cell according to claim 4, characterized in that: The Suzuki coupling reaction of step ① is as follows: under the protection of inert gas, in a mixed system consisting of organic solvent I and water, compound 1 and compound 2, potassium carbonate are reacted under the catalysis of tetrakis(triphenylphosphine)palladium, the molar ratio of compound 1 to compound 2 is 1:3; the molar ratio of potassium carbonate: compound 2=1:1; the molar ratio of tetrakis(triphenylphosphine)palladium to compound 1 is 0.02-0.025:1; the coupling reaction temperature is 65±5°C; the reaction time is until the detection compound 1 is completely consumed; The reaction product was post-treated to obtain compound 3; Step ② is: under the protection of inert gas, compound 3 is put into a tetrahydrofuran solution of 2,5-dilithiothiophene stored at -78°C, wherein the molar ratio of compound 3 to 2,5-dilithiothiophene is 2.5:1; the reaction system is naturally heated to room temperature and then the reaction is continued for 4±0.5 hours; the reaction product is post-treated to obtain compound 4; The dehydroxylation-rearrangement reaction of step ③ comprises the following steps: reacting compound 4 with tin dichloride in an organic solvent II under the protection of an inert gas; the molar ratio of compound 4 to tin dichloride is 1:5; the reaction temperature is room temperature; the reaction time is until the compound 4 is completely consumed; and the reaction product is post-treated to obtain a difluorenylquinone thiophene derivative.

6. The method for manufacturing a perovskite solar cell according to claim 5, characterized in that: In the step ①, the organic solvent I is tetrahydrofuran; the volume ratio of tetrahydrofuran to water is 10:1; 30±5 ml of tetrahydrofuran is used for every 2.0 mmol of compound 1; In the step ②, the tetrahydrofuran solution of 2,5-dilithiothiophene is prepared by reacting 2,5-dibromothiophene with n-butyl lithium in tetrahydrofuran; the molar ratio of 2,5-dibromothiophene to n-butyl lithium is 1:2.5; 5±0.5 mL of tetrahydrofuran is used for every 0.8 mmol of 2,5-dibromothiophene; the reaction temperature is -78°C; and the reaction time is 0.5 to 1 h; In the step ③: the organic solvent II is chloroform; 4±0.5 mL of tetrahydrofuran is used for every 0.2 mmol of compound 4.

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