Synthesis of organic phosphonic acid small molecule material and application of organic phosphonic acid small molecule material in perovskite solar cell

Abstract

The invention belongs to the technical field of solar cells, and relates to synthesis of an organic phosphonic acid micromolecule material and application of the organic phosphonic acid micromolecule material in perovskite solar cells, the micromolecule material adopts a phosphonic acid group as a aiming group, different carbazole aromatic nuclei as head groups, and alkyl chains with different lengths are connected with the head groups and the aiming group; when the small molecule material is used as a hole transport layer material in a perovskite solar cell device, the efficiency and the stability of the device can be effectively improved; the micromolecule material is applied to a perovskite solar cell system as an interface modification layer, good device performance is obtained, and the service life of a perovskite solar cell under a high-temperature illumination condition is prolonged; the photoelectric conversion efficiency exceeds 24%, and the preparation method of the phosphonic acid small molecule material is simple and easy to operate, and has wide application prospects and market potential.

Description

Technical field:

[0001] The invention belongs to the technical field of solar cells, and in particular relates to the application of an organic phosphonic acid small molecule as a hole transport layer material in an inverted perovskite solar cell. Background technology:

[0002] Perovskite solar cells are considered as candidates for photovoltaic applications due to the tunable band gap, superior absorption coefficient, small exciton binding energy and long charge diffusion length of perovskite. In the past decade, the certified power conversion efficiency (PCE) of perovskite solar cells has soared to more than 26% by enhancing the manufacturing strategy of perovskite solar cells and optimizing interface engineering. As a key part in the structure of inverse perovskite solar cells, high-quality hole transport layer plays an important role in extracting holes and blocking electrons simultaneously to reduce back recombination and achieve high-performance devices. Nickel oxide (NiOx) as a hole transport layer (HTL) material has the advantages of low cost, good stability, high transmittance and suitable Fermi level, but it also has some disadvantages. Due to the large band gap of nickel oxide, its light absorption range is mainly concentrated in the ultraviolet region, and its absorption of visible light and infrared light is weak, which limits its full utilization of the energy of the solar spectrum in solar cells, thereby limiting the improvement of photoelectric conversion efficiency. In addition, the preparation of nickel oxide usually requires chemical synthesis or physical deposition, which are relatively complicated processes. Summary of the invention:

[0003] The purpose of the present invention is to overcome the shortcomings of existing perovskite solar cells and propose a small molecule material based on organic phosphonic acid, a preparation method and a use method, by introducing small molecules containing heteroatoms and phosphate groups as a hole transport layer to improve the efficiency and stability of perovskite solar cells.

[0004] In order to achieve the above object, the present invention provides a small molecule material of an organic phosphonic acid molecule containing heteroatoms, using a phosphonic acid group as an anchoring group, different carbazole aromatic rings as head groups, and alkyl chains of different lengths connecting the head group and the anchoring group, and the structural formula is:

[0005]

[0006] Wherein, when Ar is selected from the group of carbazole derivatives, it is an alkylthiocarbazole group, an alkylsilylcarbazole group, a monofluorinated or difluorinated alkylthiocarbazole, an alkylsilylcarbazole group, etc., and the brackets in formula 1 are some common alkyl chain substitution groups, such as a C1-C6 alkyl chain; n≥1.

[0007] Ar is any of the following:

[0008]

[0009] The heteroatom phosphonic acid small molecule material of the present invention uses a carbazole group as an intermediate core, alkyl chains of different lengths connect the functional groups, and a phosphoric acid group is connected to the end of the alkyl chain as an anchoring group.

[0010] The heteroatom phosphonic acid small molecule material of the present invention uses different aromatic nuclei as intermediate nuclei, and performs the following structural design in the intermediate nucleus unit: (1) different heteroatoms are introduced into the intermediate nucleus to enhance the intermolecular interaction force, increase the push-pull electron interaction between molecules, and change the energy level, absorption and stacking mode of the molecule by changing the connected intermediate nucleus aromatic group, thereby regulating the device performance of the molecule; (2) the solubility of the molecule is changed by changing the length of the alkyl chain of the targeting group; (3) the introduction of phosphoric acid as the terminal group can broaden the absorption of the molecule and reduce the HOMO energy level of the small molecule material.

[0011] The present invention also provides a method for preparing an organic phosphonic acid small molecule material, which comprises the following steps:

[0012] (1) Compound Ar-H (any of the following) is reacted with bromoalkane to obtain compound A through substitution reaction:

[0013]

[0014] (2) Compound A reacts with triethyl phosphite to obtain compound B through nucleophilic substitution reaction:

[0015]

[0016] (3) Compound B is hydrolyzed to obtain final product C:

[0017]

[0018] In a preferred embodiment, the substitution reaction conditions are: the solvent is a brominated alkane, and the reaction is refluxed at 50° C. overnight under alkaline conditions.

[0019] In a preferred embodiment, the nucleophilic substitution reaction conditions are: the solvent is triethyl phosphite, the input molar amount is 5 times that of raw material A, and the reaction is carried out at 150° C. overnight.

[0020] In a preferred embodiment, the hydrolysis reaction conditions are: ultra-dry 1,4-dioxane as a solvent, adding tributylammonium bromide, reacting at room temperature overnight under nitrogen protection, and adding methanol and stirring at room temperature overnight.

[0021] The present invention also provides the use of organic phosphonic acid small molecule materials as a transport layer in a perovskite solar cell device.

[0022] The present invention also provides a method for preparing an organic phosphonic acid small molecule material YG20, wherein the structural formula of the YG20 is The specific synthetic route is as follows:

[0023] (1) Sodium hydride is added to iodinated carbazole, dissolved in tetrahydrofuran solvent, and then a protective group of chlorosilane (TBDMS) is added. The reaction is carried out at room temperature overnight to obtain compound 1. The reaction formula is shown below:

[0024]

[0025] (2) The final product obtained in the above (1) is subjected to a nucleophilic substitution reaction with compound 2, and butyl lithium reagent is used to carry out thiomethylation at -78 degrees Celsius to obtain compound 3. The reaction formula is shown below:

[0026]

[0027] (3) Compound 3 was dissolved in tetrahydrofuran solution, tetrabutylammonium bromide (TBAF) was added, and the mixture was reacted at room temperature for 15 min. The solution was extracted and spin-dried to obtain compound 4. The reaction formula is as follows:

[0028]

[0029] (4) Compound 4 was dissolved in 1,2-dibromoethane and reacted overnight at 50°C under alkaline conditions to obtain compound 5. The reaction formula is shown below:

[0030]

[0031] (5) Compound 5 was dissolved in triethyl phosphite and reacted at 150°C overnight to obtain compound 6. The reaction formula is shown below:

[0032]

[0033] (6) Compound 6 was dissolved in 1,4-dioxane, and trimethylsilyl bromide was added to react at room temperature for 24 hours to obtain a precipitate 7, which was the final product.

[0034]

[0035] The present invention provides a novel phosphonic acid small molecule, which has a suitable energy level and functional group and can effectively improve the photoelectric conversion efficiency of perovskite cells. Specifically, the structural design of the small molecule donor takes the following aspects into consideration:

[0036] 1. Targeting group: The phosphate group included in the structural design of the small molecule phosphonic acid group can pass through the lone pair of electrons contained in oxygen.

[0037] 2. Heteroatoms: The sulfur atom in the side chain structure design of the small molecule phosphonic acid group has a strong electronegativity, which reduces the energy level of the organic phosphonic acid small molecule

[0038] 3. Energy level matching: The energy levels of the small molecules match well with those of the perovskite, allowing for efficient charge transfer.

[0039] 4. Stability: Small molecules have good thermal stability and environmental stability, allowing the battery to maintain good performance even in high temperature environments.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The present invention prepares a new organic phosphonic acid small molecule material containing heteroatoms, with a phosphate group as a functional group, and performs the following structural design in the intermediate core unit: (1) introducing heteroatoms, oxygen atoms or sulfur atoms to change the energy level, absorption and stacking mode of the molecule, thereby regulating the device performance of the molecule; (2) by changing the intermediate core of the phosphate group, the performance of the device is regulated; (3) by regulating the alkyl chain connecting the phosphate group, the crystallization properties of the molecule can be changed, the relationship between solubility and crystallinity can be regulated, and the application in perovskite solar cell devices can be further optimized.

[0042] (2) The heteroatom phosphonic acid small molecule material of the present invention has a wide band gap, good film-forming properties, low synthesis cost, mild preparation conditions, and a simple synthesis route, thereby reducing the cost of optimizing perovskite devices.

[0043] (3) The heteroatom phosphonic acid material provided by the present invention is used in perovskite solar cells. The molecular synthesis is simple and matches the energy level of perovskite. Therefore, low-cost, high energy conversion efficiency and stable perovskite solar cells can be prepared.

[0044] (4) The present invention applies the synthesized material as an interface modification layer to a high-efficiency perovskite solar cell system, obtains good device performance, and extends the service life of the perovskite solar cell under high-temperature lighting conditions; its photoelectric conversion efficiency exceeds 24%, which is expected to be conducive to commercial development.

[0045] In summary, the present invention proposes an effective functional anchoring strategy, which passivates the interface defects between indium tin oxide (ITO) and perovskite through sufficient chelating sites in organic phosphonic acid small molecules. The phosphonic acid anchoring group can effectively passivate the surface defects of perovskite, alleviate the interface charge recombination between ITO and the perovskite layer, and promote the in-plane growth of perovskite grains. The preparation method of the phosphonic acid small molecule material is simple and easy to operate, and can be used to prepare perovskite solar cells, which has broad application prospects and market potential. Description of the drawings:

[0046] Figure 1 The synthetic route of the heteroatom phosphonic acid material YG20 prepared in Example 1

[0047] Figure 2 The heteroatom phosphonic acid material YG20 prepared in Example 1 1 H NMR

[0048] Figure 3 JV diagram of the perovskite solar cell based on the hybrid YG20 phosphonic acid material of the present invention Specific implementation method:

[0049] The technical solution of the present invention is further described below through specific embodiments in conjunction with the accompanying drawings.

[0050] The chemical reagents used in the following examples, petroleum ether and dichloromethane were purchased from Xi'an Haotian Chemical Reagent Factory, and 1,4-dibromobutane, triethyl phosphite, and 1,4-dioxobutane were purchased from Bid Pharmaceutical Co., Ltd.

[0051] Embodiment 1:

[0052] This embodiment relates to a method for preparing a heteroatom phosphonic acid small molecule material YG20.

[0053] Ar in the above is The preparation of small molecule phosphonic acid material YG20 is as follows:

[0054] (1) Synthesis of Compound 1: Iodinated carbazole was dissolved in tetrahydrofuran (20 mL), and sodium hydride and a protective group of silane chloride (TBDMS) were added. The molar equivalent ratio of iodinated carbazole, sodium hydride and TBDMS was 1:5:3. After reacting at room temperature for 24 hours, the reaction mixture was cooled to room temperature and the reaction solution was poured into water (100 ml). The mixture was extracted with dichloromethane (DCM) (100 mL), and the organic layer was precipitated with H 2 O, saturated NaHCO 3 , brine, and then MgSO 4 Dry, filter, and spin dry the organic solvent; purify by column chromatography (n-hexane: DCM); the product obtained by recrystallization from n-hexane is a white solid, namely compound 1; the reaction formula is as follows:

[0055]

[0056] (2) Weigh 5 g of compound 1 into a 250 mL three-necked flask, add ultra-dry tetrahydrofuran (30 mL), evacuate argon three times, and cool the reaction apparatus to -78 degrees Celsius under argon protection. After reacting for 1 hour, add 2 equivalents of dimethyl sulfide (1.3 g), and react at room temperature for 12 hours. After the reaction is completed, quench the reaction with water, extract with dichloromethane repeatedly 3-5 times, then wash with water and saline solution, collect the organic phase, remove the organic solvent by rotary evaporation, purify by column chromatography (n-hexane: DCM), and dry in a vacuum drying oven to obtain compound 3. The reaction formula is as follows:

[0057]

[0058] (3) Compound 3 was dissolved in tetrahydrofuran solution (20 mL), and tetrabutylammonium bromide (TBAF) was added, with the molar equivalent ratio of compound 3 to TBAF being 1:3; the mixture was reacted at room temperature for 15 min, and the solution was extracted and dried to obtain compound 4. The reaction formula is as follows:

[0059]

[0060] (4) Compound 4 was dissolved in 1,2-dibromoethane, and NaOH was added. The molar equivalent ratio of compound 4, 1,2-dibromoethane and NaOH was 1:25:5. The reaction was carried out under alkaline conditions at 50°C overnight. After the reaction was completed, the reaction was quenched with water, and then extracted with dichloromethane for 3-5 times, and then washed with water and salt solution. The organic phase was collected, the organic solvent was removed by rotary evaporation, and the compound 5 was purified by column chromatography (n-hexane:DCM) to obtain the compound 5. The reaction formula is as follows:

[0061]

[0062] (5) Compound 5 (1 g) was dissolved in 10 mL of triethyl phosphite and reacted at 150° C. overnight. The organic solvent was removed by rotary evaporation and purified by column chromatography (n-hexane:DCM) to obtain compound 6, with the following reaction formula:

[0063]

[0064] (6) Compound 6 (0.3 g) and trimethylsilyl bromide (5 mL) were weighed and dissolved in 1,4-dioxane (20 mL), and reacted under nitrogen protection for 24 h. After the reaction was complete, methanol (5 mL) was added to quench the reaction. After stirring at room temperature for 2 h, a large amount of water was added to generate a white solid, which was filtered and recrystallized with dichloromethane to obtain the final product YG20.

[0065] The obtained product YG20 has the structural formula:

[0066]

[0067] The product YG20 was 1 H NMR characterization, the results are as follows Figure 2 shown.

[0068] Embodiment 2:

[0069] This embodiment involves the use of YG20 prepared in Example 1 for the preparation of perovskite solar cell devices and photovoltaic performance testing.

[0070] The perovskite solar cell includes a stacked transparent conductive glass, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode. The specific preparation method is as follows: after cleaning the transparent conductive glass (ITO sheet), spin-coat the hole transport layer prepared by YG20 (YG20 is dissolved in chlorobenzene with a concentration of 10 mg / mL), the spin coater parameters are: 3000r / min, acceleration 1000r / 30s, put on a 100°C hot stage after spinning one sheet, and transfer all the sheets to a 150°C hot stage after spinning. Anneal at 150°C for 30min, and perform ozone cleaning for 10min after annealing; put the sheet into a glove box at a humidity of 40%, and fill and discharge the air 3 times; start static spin coating of the perovskite drive solution, and then spin coat the anti-solvent (ethyl acetate EA). After the perovskite layer is spin-coated and the anti-solvent is finished, take it out of the glove box and anneal it at 150℃ / 10min with a humidity of 20-30%. After the annealing is finished, the color of the film turns gray and it is put back into the glove box and the passivation layer is spin-coated. After the passivation layer is spun, PCBM is evaporated, and then silver electrode metal is evaporated as the negative electrode to test the performance of the solar cell. The solar cell prepared with nickel oxide as the hole transport layer material is the control group. The current-voltage (JV) characteristic curve of its battery device performance is shown in Figure 1 and Table 1. Figure 1 As can be seen from Table 1, the open circuit voltage V OC is 1.186V, short-circuit current density J SC 24.95mA / cm 2 The filling factor FF is 0.8292 and the photoelectric conversion efficiency is 24.19%, which improves the device efficiency and device stability.

[0071] Table 1 Device performance

[0072]

Claims

1. An organic phosphonic acid small molecule material, characterized in that: Phosphonic acid groups are used as anchoring groups, different carbazole aromatic rings are used as head groups, and alkyl chains of different lengths are used to connect the head groups and the anchoring groups. The structural formula is: Wherein, Ar is any of the following:

2. The method for preparing the organic phosphonic acid small molecule material according to claim 1, characterized in that: It includes the following steps: (1) Compound Ar-H is reacted with bromoalkane to obtain compound A: (2) Compound A reacts with triethyl phosphite to obtain compound B through nucleophilic substitution reaction: (3) Compound B is hydrolyzed to obtain final product C:

3. The method for preparing the organic phosphonic acid small molecule material according to claim 2, characterized in that: When Ar is The specific synthetic route is as follows: (1) Sodium hydride is added to iodinated carbazole, dissolved in tetrahydrofuran solvent, and then a protective group of silane chloride is added. The reaction is carried out at room temperature overnight to obtain compound 1. The reaction formula is shown below: (2) The final product obtained in the above (1) is subjected to a nucleophilic substitution reaction with compound 2, and butyl lithium reagent is used to carry out thiomethylation at -78 degrees Celsius to obtain compound 3. The reaction formula is shown below: (3) Compound 3 was dissolved in tetrahydrofuran solution, tetrabutylammonium bromide was added, reacted at room temperature, and the solution was extracted and spin-dried to obtain compound 4. The reaction formula is as follows: (4) Compound 4 was dissolved in 1,2-dibromoethane and reacted overnight at 50°C under alkaline conditions to obtain compound 5. The reaction formula is shown below: (5) Compound 5 was dissolved in triethyl phosphite and reacted at 150°C overnight to obtain compound 6. The reaction formula is shown below: (6) Compound 6 was dissolved in 1,4-dioxane, and trimethylsilyl bromide was added to react at room temperature for 24 hours to obtain a precipitate 7, which was the final product.

4. Use of the organic phosphonic acid small molecule material according to claim 1 as a transport layer in a perovskite solar cell device.

5. A perovskite solar cell, characterized in that: The perovskite solar cell comprises a transparent conductive glass, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode which are stacked, and the hole transport layer is the organic phosphonic acid small molecule material according to claim 1.

6. A photovoltaic cell, characterized in that: Includes the perovskite solar cell described in claim 5.

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