Novel material for improving perovskite film, perovskite solar cell and preparation method

Abstract

The application discloses a novel material for improving perovskite films, a perovskite solar cell and a preparation method. The novel material is applied between an electron transport layer and a perovskite light-absorbing layer in the perovskite solar cell, and the novel material is 1,4-bis(3,6-bis(4-(3,6-dialkoxy-9H-carbazole-9-yl)phenyl)-9H-carbazole-9-yl)benzene, wherein the two alkyl groups in the 3,6-dialkoxy group can be the same or different. The novel material provided by the application is arranged between the electron transport layer and the perovskite light-absorbing layer in the perovskite solar cell, which is conducive to promoting the formation of larger perovskite grains and effectively reducing the roughness of the surface of the perovskite light-absorbing layer, and thus the electron transport stability, the fill factor and the photoelectric conversion efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a new material for improving perovskite film, a perovskite solar cell and a preparation method. BACKGROUND

[0002] As a new type of photovoltaic cell, the perovskite solar cell is popular due to its large spectral absorption range, simple preparation process and low cost. At present, although the photoelectric conversion efficiency of the perovskite solar cell has been greatly improved, the perovskite light-absorbing layer (i.e. perovskite film) has a relatively rough surface and a large number of grain boundaries, which leads to a large probability of electron and hole recombination at the grain boundaries, affecting the electron transport and the stability of the electron transport layer. SUMMARY

[0003] Therefore, the present application provides a new material for improving perovskite film, a perovskite solar cell and a preparation method. The new material is arranged between the electron transport layer and the perovskite light-absorbing layer (i.e. perovskite film) in the perovskite solar cell, which is conducive to promoting the formation of larger perovskite grains and effectively reducing the roughness of the perovskite light-absorbing layer surface, thereby improving the electron transport stability, fill factor and photoelectric conversion efficiency.

[0004] To solve the above technical problems, the present application provides the following technical solutions:

[0005] In a first aspect, the present application provides a new material for improving perovskite film, the molecular structure of the new material is as follows:

[0006] As shown in the general formula (I):

[0007] General formula (I)

[0008]

[0009] Wherein, R1 and R2 are alkyl groups, and R1 and R2 are the same or different.

[0010] Optionally, R1 and R2 are both alkyl groups with 1-6 carbon atoms.

[0011] Optionally, R1 is a methyl group or a n-hexyl group; and R2 is a methyl group or a n-hexyl group.

[0012] In a second aspect, the present application provides a perovskite solar cell, comprising: a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer and a top electrode which are sequentially stacked.

[0013] The perovskite solar cell further comprises a passivation layer arranged between the electron transport layer and the perovskite light-absorbing layer, which is formed based on the new material for improving perovskite film provided in the first aspect.

[0014] Optionally, the passivation layer is formed by coating an organic solution containing the new material on the electron transport layer perovskite light-absorbing layer.

[0015] Optionally, the passivation layer is obtained by the following operations:

[0016] coating an organic solution containing the new material on the electron transport layer to form a wet organic thin film;

[0017] coating a precursor solution for preparing the perovskite light-absorbing layer on the wet organic thin film, and then annealing treatment, so as to form a layered passivation layer and the perovskite light-absorbing layer on the electron transport layer.

[0018] Optionally, the thickness of the passivation layer is 60nm-85nm.

[0019] Optionally, the concentration of the new material in the organic solution for forming the passivation layer is 0.7mg / mL-1.3mg / mL.

[0020] Optionally, the rate of coating the organic thin film is 2500rpm / s-3500rpm / s.

[0021] Optionally, the coating time of the organic thin film is 20s-35s.

[0022] Optionally, the passivation layer is obtained by the following operations:

[0023] coating an organic solution containing the new material on the electron transport layer to form a wet organic thin film;

[0024] coating a precursor solution for preparing the perovskite light-absorbing layer on the wet organic thin film, and then annealing treatment, so as to form a layered passivation layer and the perovskite light-absorbing layer on the electron transport layer.

[0025] In a third aspect, the present application provides a preparation method of the new material according to the first aspect.

[0026] Step A, synthesizing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene by using 1,4-bis(9H-carbazol-9-yl)benzene;

[0027] Step B, synthesizing 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene by using 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole.

[0028] Optionally, the step A comprises:

[0029] Step A1, mixing 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide to form a mixture;

[0030] Step A2, adding tetrahydrofuran (THF) to the mixture, and controlling the reaction temperature at 95-105℃ and the reaction time at 7-9h, to synthesize 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene.

[0031] Optionally, step B comprises: mixing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole, and adding a certain amount of carbonate, bistrimethylphenylphosphine-containing compound and organic solvent, and controlling the reaction temperature at 115-125℃ and the reaction time at 7-9h, to synthesize 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene.

[0032] Optionally, the carbonate is potassium carbonate or / and sodium carbonate.

[0033] Optionally, the mass ratio of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide is 1:2-1:4.5.

[0034] Optionally, the mass-volume ratio (g:mL) of the mixture formed in step A1 and tetrahydrofuran is 1:10-1:20.

[0035] Optionally, the mass ratio of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole and 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene is 1:1.2-1:1.5.

[0036] Optionally, the mass ratio of the bistrimethylphenylphosphine-containing compound, the carbonate and the 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole is 1:(4.2-4.6):(5.8-6.2).

[0037] Optionally, the mass-volume ratio (g:mL) of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole and the organic solvent is 1:34-1:57.

[0038] The technical scheme of the first aspect of the application has the following advantages or beneficial effects:

[0039] The novel material for improving the perovskite film provided by the embodiment of the application is applied between the electron transport layer and the perovskite light-absorbing layer in the perovskite solar cell. Due to the presence of multiple carbazole structures in the molecular structure of the novel material, the novel material is beneficial to hole transport. In addition, the novel material introduces nitrogen atoms for perovskite grain growth in the perovskite light-absorbing layer, so that the perovskite grains are larger. That is, the presence of the novel material is beneficial to promoting the perovskite light-absorbing layer to form larger perovskite grains, beneficial to electron transport, and forming hydrogen bonds by the action of multiple alkoxy groups and perovskite in the perovskite light-absorbing layer, which helps to make the surface of the perovskite light-absorbing layer more flat, reduce the roughness of the perovskite light-absorbing layer, and better isolate the electron transport layer and the hole transport layer, so as to avoid the electron transport layer and the hole transport layer from being combined at the grain boundary of the perovskite light-absorbing layer, thereby effectively improving the stability of electron transport of the perovskite solar cell.

[0040] In addition, the novel material is applied between the electron transport layer and the perovskite light-absorbing layer in the perovskite solar cell. By reducing the roughness of the perovskite light-absorbing layer, the filling factor of the perovskite solar cell can be effectively improved, and the photoelectric conversion efficiency of the perovskite solar cell is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a partial cross-sectional structure schematic diagram of a perovskite solar cell according to an embodiment of the application;

[0042] Figure 2 is a main flow schematic diagram of a preparation method of a novel material according to an embodiment of the application;

[0043] Figure 3 is a chemical reaction formula schematic diagram of preparation of an intermediate product in a preparation process of a novel material according to an embodiment of the application;

[0044] Figure 4 is a chemical reaction formula schematic diagram of preparation of a novel material in a preparation process of a novel material according to an embodiment of the application;

[0045] Figure 5 is a main flow schematic diagram of a preparation method of a perovskite solar cell according to an embodiment of the application;

[0046] Figure 6 is a performance comparison diagram of perovskite solar cells prepared based on embodiment 2 and comparative examples according to an embodiment of the application;

[0047] Figure 7 is an atomic force microscope comparison diagram of light-absorbing layers of perovskite light-absorbing layers prepared based on embodiment 2 and comparative examples according to an embodiment of the application;

[0048] Figure 8 is a scanning electron microscope contrast chart of the perovskite light-absorbing layer prepared according to the embodiment 2 and the comparative example of the present application.

[0049] The reference signs are as follows:

[0050] 10 - substrate; 20 - electron transport layer; 30 - passivation layer; 40 - perovskite light-absorbing layer; 50 - hole transport layer; 60 - top electrode. DETAILED DESCRIPTION

[0051] The new material for improving perovskite film provided by the embodiments of the present application is mainly applied to perovskite solar cells and perovskite solar cell preparation processes. In addition, according to the requirements and the functions and effects of the new material for improving perovskite film provided by the embodiments of the present application, the new material can also be applied to other optoelectronic devices containing perovskite film, such as light-emitting devices, transistors, sensors, etc.

[0052] It is worth noting that the perovskite solar cell targeted by the embodiments of the present application can be a single-junction perovskite solar cell or a tandem perovskite solar cell. The single-junction perovskite solar cell includes a multi-layer thin film structure of an electron transport layer, a perovskite light-absorbing layer (i.e. the perovskite film described above), a hole transport layer, and an electrode layer, etc. The single-junction perovskite solar cell realizes photoelectric conversion through the "sandwich" structure of the electron transport layer-perovskite light-absorbing layer-hole transport layer. The tandem perovskite solar cell can be understood as stacking the "electron transport layer-perovskite light-absorbing layer-hole transport layer" structure on the basis of a crystalline silicon or amorphous silicon solar cell (such as a perovskite solar cell, a crystalline silicon solar cell, a thin-film solar cell, etc.). The "electron transport layer-perovskite light-absorbing layer-hole transport layer" structure is connected in series with the solar cell on which it is stacked, forming a "series" cell that can absorb a wider spectrum of sunlight. Therefore, the tandem perovskite solar cell can be a full-perovskite tandem cell, a crystalline silicon / perovskite tandem cell, a thin-film cell (such as copper indium gallium selenide) / perovskite tandem cell, etc.

[0053] Regardless of the single-junction perovskite solar cell or the tandem perovskite solar cell, the perovskite light-absorbing layer has a relatively rough surface and a large number of grain boundaries, which leads to a relatively high probability of electron and hole recombination at the grain boundaries, affecting the electron transport and the stability of the electron transport layer, and affecting the photoelectric conversion performance and the fill factor of the perovskite solar cell.

[0054] In order to solve the problems existing in the current perovskite solar cells, the embodiment of the present application provides a new material for improving perovskite film, a perovskite solar cell and a preparation method, which aims to promote the formation of larger size perovskite grains and reduce the roughness of the perovskite light-absorbing layer by adding an organic material layer containing the new material, thereby avoiding the recombination of electrons and holes at the grain boundary, effectively improving the stability of electron transport of the perovskite solar cell, and effectively improving the photoelectric conversion efficiency of the perovskite solar cell and the fill factor of the perovskite solar cell.

[0055] The embodiment of the present application provides a new material for improving perovskite film. The molecular structure of the new material for improving perovskite film is shown in general formula (I):

[0056] General formula (I):

[0057]

[0058] Wherein, R1 and R2 are alkyl groups, and R1 and R2 are the same or different.

[0059] Wherein, the alkyl group of R1 and R2 can be a straight chain structure or a branched chain structure. Preferably, the number of carbon atoms of the alkyl group of R1 and R2 is 1-6. More preferably, the alkyl group of R1 and R2 is a straight chain structure and R1 and R2 are the same. Further preferably, R1 is methyl or n-hexyl; R2 is methyl or n-hexyl.

[0060] Wherein, the above-mentioned new material for improving perovskite film is generally applied between the electron transport layer 20 and the perovskite light-absorbing layer 40 in the perovskite solar cell. Through the structure of the above-mentioned general formula (I), the new material is convenient to prepare, and at the same time, the new material has more carbazole structures to provide more hydrogen bonds for the perovskite light-absorbing layer 40, and form a better fit with the perovskite light-absorbing layer 40.

[0061] Further, by designing the molecular structure of the above-mentioned new material as a symmetrical structure, more hydrogen bonds are provided for the perovskite light-absorbing layer 40 as much as possible, which ensures that the new material is used between the electron transport layer 20 and the perovskite light-absorbing layer 40 in the perovskite solar cell, can reduce the roughness of the perovskite light-absorbing layer 40, and is beneficial to the growth of perovskite grains in the perovskite light-absorbing layer 40.

[0062] The material required for forming the new material includes 1,4-bis(9H-carbazol-9-yl)benzene, N-bromosuccinimide, tetrahydrofuran, 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole, potassium / sodium carbonate and a compound containing bistriphenylphosphine. The two alkyl groups in 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole correspond to R1 and R2 respectively. The potassium / sodium carbonate means that the material required for the new material can be potassium carbonate, sodium carbonate or a mixture of potassium carbonate and sodium carbonate.

[0063] The new material is applied between the electron transport layer 20 and the perovskite light absorption layer 40 in the perovskite solar cell. The presence of multiple carbazole structures in the molecular structure of the new material is conducive to hole transport. Nitrogen atoms are introduced for the growth of perovskite grains in the perovskite light absorption layer 40, so that the perovskite grains are larger (i.e., the presence of the new material is conducive to promoting the formation of larger perovskite grains in the perovskite light absorption layer 40), which is conducive to electron transport. Hydrogen bonds are formed between multiple alkoxy groups and perovskite in the perovskite light absorption layer 40, which helps to make the surface of the perovskite light absorption layer 40 smoother, reduces the roughness of the perovskite light absorption layer 40, and can better isolate the electron transport layer 20 and the hole transport layer 50, avoiding the recombination of the electron transport layer 20 and the hole transport layer 50 at the grain boundaries of the perovskite light absorption layer 40, so as to effectively improve the stability of electron transport in the perovskite solar cell.

[0064] In addition, the new material is applied between the electron transport layer 20 and the perovskite light absorption layer 40 in the perovskite solar cell, which can effectively improve the fill factor and photoelectric conversion efficiency of the perovskite solar cell by reducing the roughness of the perovskite light absorption layer 40.

[0065] Further, the embodiment of the present application provides a perovskite solar cell. Figure 1 A partial cross-sectional structure schematic diagram of the perovskite solar cell is shown. As shown in FIG. 1, the perovskite solar cell includes a substrate 10, an electron transport layer 20, a perovskite light absorption layer 40 and a hole transport layer 50. Figure 1As shown, the perovskite solar cell provided by the embodiment of the present application can include: a substrate 10, an electron transport layer 20, a perovskite light-absorbing layer 40, a hole transport layer 50 and a top electrode 60 which are sequentially stacked, and in addition, the perovskite solar cell can further include a passivation layer 30 which is arranged between the electron transport layer 20 and the perovskite light-absorbing layer 40, and the passivation layer 30 is formed based on the new material shown in the above general formula (I) for improving the perovskite thin film provided by the above embodiment. Wherein, the passivation layer 30 and the perovskite light-absorbing layer 40 are in contact. The contact between the passivation layer 30 and the perovskite light-absorbing layer 40 generally means that the passivation layer 30 and the perovskite light-absorbing layer 40 are directly in contact, and there is no other functional layer between them.

[0066] Wherein, the hole transport layer 50 can further be provided with other functional layers such as an anti-reflection layer and a conductive layer, etc.

[0067] In addition, the thickness of the passivation layer 30 can be 60nm~85nm. For example, the thickness of the passivation layer 30 can be 60nm, 62nm, 65nm, 67nm, 69nm, 70nm, 72nm, 75nm, 78nm, 80nm, 82nm, 85nm, etc.

[0068] The presence of multiple carbazole structures in the passivation layer 30 formed by the new material is conducive to the transmission of holes in the hole transport layer 50 located on the perovskite light-absorbing layer 40, and introduces nitrogen atoms for the growth of perovskite grains in the perovskite light-absorbing layer 40, so that the perovskite grains are larger, which is conducive to the transmission of electrons in the electron transport layer 20 located below the perovskite light-absorbing layer 40, and forms hydrogen bonds by the action of multiple alkoxy groups with perovskite in the perovskite light-absorbing layer 40, which helps to make the surface of the perovskite light-absorbing layer 40 more flat, reduces the roughness of the perovskite light-absorbing layer 40, and can better isolate the electron transport layer 20 and the hole transport layer 50, avoiding the recombination of the electron transport layer 20 and the hole transport layer 50 at the grain boundary of the perovskite light-absorbing layer 40, so as to effectively improve the stability of the electron transport of the perovskite solar cell.

[0069] In addition, the passivation layer 30 formed by the new material can effectively reduce the roughness of the perovskite light-absorbing layer 40, and can effectively improve the fill factor and photoelectric conversion efficiency of the perovskite solar cell.

[0070] The passivation layer 30 of the perovskite solar cell described above can be formed by coating an organic solution containing the new material on the electron transport layer 20.

[0071] Specifically, the passivation layer 30 formed on the electron transport layer 20 can be obtained by the following operations:

[0072] Coating an organic solution containing the new material on the electron transport layer 20 to form a wet organic thin film;

[0073] The precursor solution for preparing the perovskite light-absorbing layer 40 is coated on the wet organic thin film, and then annealing treatment is performed, thereby forming the laminated passivation layer 30 and perovskite light-absorbing layer 40 on the electron transport layer 20.

[0074] The passivation layer 30 can be formed into a wet organic thin film by spin coating, spray coating or blade coating.

[0075] The concentration of the new material in the organic solution used for forming the wet organic thin film is 0.7-1.3 mg / mL. For example, the concentration of the new material in the organic solution can be 0.7 mg / mL, 0.8 mg / mL, 0.9 mg / mL, 1.0 mg / mL, 1.1 mg / mL, 1.2 mg / mL, 1.3 mg / mL, etc.

[0076] Further, the rate of coating the wet organic thin film is generally 2500 rpm / s-3500 rpm / s. For example, the rate of coating the wet organic thin film can be 2500 rpm / s, 2600 rpm / s, 2750 rpm / s, 2900 rpm / s, 3000 rpm / s, 3100 rpm / s, 3300 rpm / s, 3500 rpm / s, etc.

[0077] Further, the coating time of the wet organic thin film can be 20 s-35 s. For example, the coating time of the wet organic thin film can be 20 s, 21 s, 22 s, 24 s, 25 s, 27 s, 29 s, 30 s, 32 s, 34 s, 35 s, etc.

[0078] By first forming a wet organic thin film with the new material, and then performing annealing treatment after preparing the perovskite light-absorbing layer 40, the flatness of the perovskite light-absorbing layer 40 is ensured. In addition, during the treatment process, the carbazole structure in the passivation layer 30 introduces nitrogen atoms into the perovskite light-absorbing layer 40, so that the perovskite grains are larger. In addition, during the treatment process, the multiple alkoxy groups introduced by the passivation layer 30 form hydrogen bonds with the perovskite in the perovskite light-absorbing layer 40, which helps to make the surface of the perovskite light-absorbing layer more flat, reduces the roughness of the perovskite light-absorbing layer 40, and avoids the electron transport layer 20 and the hole transport layer 50 from being recombined at the grain boundaries of the perovskite light-absorbing layer 40, so as to effectively improve the stability of the electron transport of the perovskite solar cell, and effectively improve the fill factor of the perovskite solar cell, thereby improving the photoelectric conversion efficiency of the perovskite solar cell.

[0079] Further, the present application provides a preparation method of the new material. Figure 2 The main flowchart of the preparation method of the new material provided by the present application is shown in FIG. 1. Figure 2 As shown in FIG. 1, the preparation method of the new material can include:

[0080] Step S201: Synthesizing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene from 1,4-bis(9H-carbazol-9-yl)benzene;

[0081] The chemical reaction formula of synthesizing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene in this step is shown as Figure 3

[0082] Specifically, the process of synthesizing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene in this step can be: mixing 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide (NBS) to form a mixture; adding tetrahydrofuran (THF) to the mixture, and controlling the reaction temperature to be 95-105°C and the reaction time to be 7-9h to synthesize 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene.

[0083] In order to control the usage amount of each raw material and effectively improve the yield of 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene, the mass ratio of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide (C4H4BrNO2, NBS) is 1:2-1:4.5. That is, 1g of 1,4-bis(9H-carbazol-9-yl)benzene is mixed with 2-4.5g of N-bromosuccinimide. For example, the mass ratio of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide can be 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.3, 1:3.5, 1:3.7, 1:4, 1:4.2, 1:4.5, etc. By controlling the mass ratio of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide, the waste of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide raw materials can be reduced as much as possible, and the yield of the intermediate product in the subsequent step S202 can be ensured.

[0084] In addition, the mass-volume ratio of the mixture of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide formed in this step and tetrahydrofuran is 1:10-1:20, wherein the mass-volume ratio refers to the volume (mL) of tetrahydrofuran added per 1g of the mixture, which is 10-20mL. The volume of tetrahydrofuran added to 3g of the mixture is 30-60mL. For example, the mass-volume ratio of the mixture and tetrahydrofuran can be 1:10, 1:12, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, and 1:20, etc.

[0085] ​The reaction temperature used in this step is 95-105°C, and the reaction time is 7-9h. For example, the reaction temperature can be 95°C, 96°C, 98°C, 99°C, and 100°C, and the reaction time can be 7h, 7.2h, 7.5h, 7.8h, 8h, 8.3h, 8.5h, 8.8h, 9h, etc.

[0086] Step S202: Synthesizing 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl)-9H-carbazol-9-yl)benzene from 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole.

[0087] wherein the two alkyl groups in 3,6-dialkoxy in 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole correspond to R1 and R2 of the novel material to be formed. The two alkoxy groups can be two methoxy groups or two n-hexyloxy groups or a combination of one methoxy group and one n-hexyloxy group. The chemical reaction formula of the novel material obtained in this step S202 is shown in Figure 4 It is worth mentioning that the reaction formula shown in Figure 4 is an example of the reaction formula with 3,6-dimethoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole as the reactant. For the case where 3,6-dialkoxy in the reactant 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole is two n-hexyloxy groups or a combination of one methoxy group and one n-hexyloxy group, it is only necessary to replace 3,6-dimethoxy in the reaction formula with the corresponding alkyl group, which is similar to the reaction formula shown in Figure 4 , and will not be described here.

[0088] Specifically, the process for synthesizing 1,4-bis(3,6-bis(4-(3,6-dialkoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene in this step can be: mixing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole, and adding a certain amount of potassium carbonate / sodium carbonate, a bistriphenylphosphine-containing compound, and an organic solvent, and controlling the reaction temperature to be 115-125°C and the reaction time to be 7-9h, to synthesize 1,4-bis(3,6-bis(4-(3,6-dialkoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene. For example, the reaction temperature in this step can be 115°C, 116°C, 119°C, 120°C, 122°C, 123°C, 124°C, 125°C, etc., and the reaction time can be 7h, 7.1h, 7.4h, 7.5h, 7.6h, 7.9h, 8h, 8.2h, 8.3h, 8.5h, 8.8h, 9h, etc.

[0089] wherein the mass ratio of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole to 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene can be 1:1.2-1:1.5, for example, the mass ratio of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole to 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene can be 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc.

[0090] Further, the mass ratio of the bistriphenylphosphine-containing compound, potassium / sodium carbonate and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole is 1:(4.2~4.6):(5.8~6.2), i.e. the mass ratio of the bistriphenylphosphine-containing compound: potassium / sodium carbonate: 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole = 1:(4.2~4.6):(5.8~6.2). For example, the mass ratio of the bistriphenylphosphine-containing compound: potassium / sodium carbonate: 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole can be 1:4.2:5.8, 1:4.4:6, 1:4.5:6.2, 1:4.6:6.1, 1:4.6:6.2, etc. In this case, the bistriphenylphosphine-containing compound is generally tetrakis(triphenylphosphine)palladium, and the mass ratio of potassium / sodium carbonate, tetrakis(triphenylphosphine)palladium and the monocarbazole structure is controlled to ensure that the target product is obtained and the yield of the target product is effectively improved.

[0091] Further, the mass / volume ratio of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole and the organic solvent in this step is 1:34~1:57, i.e. the volume of the organic solvent added per 1g of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole is 34~57mL. For example, the volume / mass ratio of the organic solvent and the monocarbazole structure can be 1:34, 1:35, 1:38, 1:40, 1:42, 1:45, 1:47, 1:48, 1:50, 1:52, 1:55, 1:57, etc. For example, 0.88g of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole, and the volume of the organic solvent added can be 30mL, 35mL, 40mL, 45mL, 50mL, etc. The organic solvent is generally a benzene-based solvent, and preferably, the organic solvent is toluene.

[0092] The embodiment of the present application can effectively control the target product to be 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole by combining the mass ratio of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide 1:2~1:4.5, the mass-volume ratio of the mixture of 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide and tetrahydrofuran 1:10~1:20, the mass ratio of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole and intermediate product 1:1.2~1:1.5, the mass ratio of bistriphenylphosphine-containing compound, potassium carbonate / sodium carbonate and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole 1:4.4:6, and the volume-mass ratio of 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole and organic solvent 1:34~1:57, and effectively improve the yield of the target product. Figure 4 The present application embodiment can effectively improve the yield of the target product.

[0093] Further, the present application embodiment provides a preparation method of a perovskite solar cell. Figure 5 The present application embodiment provides a preparation method of a perovskite solar cell. As shown in the figure, the preparation method of the perovskite solar cell can include: Figure 5 The present application embodiment provides a preparation method of a perovskite solar cell. As shown in the figure, the preparation method of the perovskite solar cell can include:

[0094] Step S501: forming a wet organic thin film on the formed electron transport layer 20 by using an organic solution containing the novel material provided in the above embodiment;

[0095] The concentration of the novel material in the organic solution used in step S501 is 0.7~1.3mg / mL. For example, the concentration of the novel material in the organic solution can be 0.7mg / mL, 0.8mg / mL, 0.9mg / mL, 1.0mg / mL, 1.1mg / mL, 1.2mg / mL, 1.3mg / mL, etc.

[0096] Step S502: preparing a perovskite light-absorbing layer 40 on the wet organic thin film and annealing treatment;

[0097] Step S503: preparing a hole transport layer 50 on the perovskite light-absorbing layer 40 and annealing treatment.

[0098] The preparation method of the perovskite solar cell is characterized in that: a new material is used to form a wet organic thin film, and annealing treatment is performed after the perovskite light-absorbing layer 40 is prepared, so as to ensure the flatness of the perovskite light-absorbing layer 40; and the treatment process introduces nitrogen atoms into the perovskite light-absorbing layer 40 through the carbazole structure introduced by the passivation layer 30, so that the perovskite crystal grains are larger, and multiple alkoxy groups are introduced to form hydrogen bonds with the perovskite in the perovskite light-absorbing layer 40, which helps to make the surface of the perovskite light-absorbing layer 40 more flat, reduce the roughness of the perovskite light-absorbing layer 40, and avoid the recombination of the electron transport layer 20 and the hole transport layer 50 at the grain boundary of the perovskite light-absorbing layer 40, so as to effectively improve the stability of the electron transport of the perovskite solar cell, and effectively improve the fill factor of the perovskite solar cell, and further improve the photoelectric conversion efficiency of the perovskite solar cell.

[0099] The technical solutions provided by the present application are further described and explained below based on specific embodiments. The following description is only used to explain the related application of the present application, and is not a limitation of the present application. The embodiments and the drawings only show part of the application.

[0100] Example 1: Process for preparing novel materials

[0101] In step S1, 1,4-di(9H-carbazol-9-yl)benzene and N-bromosuccinimide are mixed in a mass ratio of 1:2.1, a certain amount of solvent tetrahydrofuran is added (the mass-volume ratio of 1,4-di(9H-carbazol-9-yl)benzene to tetrahydrofuran is 1:30, that is, 30 ml of tetrahydrofuran is added for every 1 g of 1,4-di(9H-carbazol-9-yl)benzene), and the reaction is carried out at 100℃ for 8 h to obtain the product 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene. The reaction formula of this step is shown in Figure 3

[0102] ​Step S2: mixing the product obtained in step S1 with a certain amount of 3,6-dimethoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole (the mass ratio of 3,6-dimethoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole to the product obtained in step A1 is 1:1.2), and adding a certain amount of potassium carbonate, tetrakis(triphenylphosphine)palladium (the mass ratio of the tetrakis(triphenylphosphine)palladium, potassium carbonate and 3,6-dimethoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole is 1:4.4:6), toluene (the volume to mass ratio of toluene to 3,6-dimethoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole is 45:1, that is, 45 ml of toluene is added for every 1 g of 3,6-dimethoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole), and reacting at 120°C for 8 h to obtain the target product 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene, that is, a new material, and the reaction formula of this step is shown in Figure 4

[0103] Example 2:

[0104] Step S3: sequentially washing the conductive glass serving as the substrate 10 with a mixture of glass cleaning solution and deionized water (the volume ratio of glass cleaning solution to deionized water in the mixture is 1:50), deionized water and acetone, and then blowing dry with dry nitrogen;

[0105] Step S4: treating the conductive glass in step S3 under ultraviolet ozone conditions for 20 min;

[0106] Step S5: spin coating a SnO2 layer on the conductive glass in step S4;

[0107] The specific process of this step S5 is as follows: first, mix SnO2 nanodispersion liquid with deionized water according to a volume ratio of 1:4, and ultrasonic for 15 min, then spin coat on the conductive glass after ultrasonic, and control the spin coating speed to be 3000 rpm, the spin coating time to be 30 s, and the spin coating acceleration to be 3000 rpm / s during the spin coating process, and then transfer the conductive glass to a heating table, and add annealing at 150°C for 30 min, so as to obtain a dense SnO2 electron transport layer 20;

[0108] Step S6: treating the electron transport layer 20 obtained in step S5 under ultraviolet ozone conditions for 20 min;​

[0109] Step S7: A certain amount of 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene prepared in Example 1 was weighed and dissolved in a certain amount of chlorobenzene to prepare a solution with a concentration of 1 mg / mL;

[0110] Step S8: The solution obtained in S7 was coated on the electron transport layer 20 by spin coating to form a wet organic thin film, the spin coating speed was 3000 rpm, the time was 30 s, and the acceleration was 3000 rpm / s;

[0111] Step S9: The precursor solution was quickly spin-coated on the organic wet thin film and annealed to obtain a laminated passivation layer 30 and perovskite light-absorbing layer 40 on the electron transport layer 20;

[0112] Specifically, the process of this step S9: 33.7 mg of MACl, 705 mg of PbI2 and 240 mg of FAI were dissolved in 1 mL of DMF / DMSO (volume ratio of 8:1), and then stirred at room temperature (25°C) for 8 h to obtain a precursor solution; after stirring was completed, the precursor solution was spin-coated on the conductive glass treated in step S8, and the spin coating was divided into two steps, the first step was 1000 rpm for 10 s, and the acceleration was 1000 rpm / s; the second step was 5000 rpm for 30 s, and the acceleration was 5000 rpm / s, and 120 μL of anti-solvent ethyl acetate was slowly added in the last 10 seconds; after spin coating was completed, the conductive glass on which the precursor solution was spin-coated was placed on a hot stage at 100°C and annealed for 1 h to obtain a perovskite light-absorbing layer 40;

[0113] Step S10: After the perovskite light-absorbing layer 40 obtained in S9 was cooled, a hole transport layer 50 was prepared;

[0114] The specific process is as follows: 520 mg of Li-TFSI was dissolved in 1 mL of acetonitrile solution to obtain a Li-TFSI solution; 300 mg of Co-TFSI was dissolved in 1 mL of acetonitrile solution to obtain a Co-TFSI solution; 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and after stirring uniformly, a 72.3 mg / mL Spiro-OMeTAD solution was obtained; 18 μL of Li-TFSI solution and 29 μL of Co-TFSI solution were taken and added to the Spiro-OMeTAD solution, and stirred at room temperature for 30 minutes to obtain a mixed solution for preparing the hole transport layer 50;

[0115] The mixed solution for preparing the hole transport layer 50 is applied to the perovskite light absorbing layer 40 by spin coating at a spin coating speed of 3000 rpm, a time of 30 s, an acceleration of 3000 rpm / s, and annealing to obtain the hole transport layer 50;

[0116] Step S11: evaporating a top electrode 60 on the hole transport layer 50; thus, a perovskite solar cell is obtained.

[0117] Specifically, in this step, a metal Au electrode with a thickness of 81 nm is prepared on the hole transport layer 50 .

[0118] Comparative Example:

[0119] This comparative example is prepared only by steps S3 to S6 and steps S9 to S11 in Example 2 above. In addition, in the step corresponding to step S9 in this comparative example, the precursor solution is directly spin-coated on the electron transport layer 20, and annealing is performed to obtain the perovskite light absorbing layer 40 directly coated on the electron transport layer 20. In other words, steps S7 and S8 above are omitted in this comparative example.

[0120] The performance of the perovskite solar cell obtained in the comparative example and Example 2 and the surface characterization of the perovskite light absorbing layer 40 were performed, and the following results were obtained: Figure 6 The performance comparison chart of perovskite solar cells shown in the figure is as follows: Figure 7 The atomic force microscope comparison diagram shown and Figure 8 The scanning electron microscope comparison image of the perovskite light absorbing layer 40 is shown.

[0121] from Figure 6 It can be seen that the photovoltaic parameters of the comparative device are: short-circuit current density JSC is 23.85 mA / cm 2 , the open circuit voltage VOC is 1.123V, the fill factor FF is 80.31%, and the photoelectric conversion efficiency PCE is 21.51%; the photovoltaic parameters of the device of Example 2 are: the short circuit current density JSC is 24.00mA / cm 2 , the open circuit voltage VOC is 1.144V, the fill factor FF is 85.04%, and the photoelectric conversion efficiency PCE is 23.35%. It can be clearly seen from the figure that the new material provided by the embodiment of the present invention forms a passivation layer 30 between the electron transport layer 20 and the perovskite light absorption layer 40. The passivation layer 30 can achieve doping of the perovskite light absorption layer 40 and passivation of the interface of the perovskite light absorption layer 40. Compared with the perovskite solar cell of the comparative example of the prior art, the short circuit current density JSC and the open circuit voltage VOC are improved. The most obvious improvement is the fill factor FF, which has increased from 80.31% to 85.04%.

[0122] The perovskite light-absorbing layer 40 of the comparative example and Example 2 was characterized by atomic force microscopy, and the atomic force microscopy contrast chart is shown in FIG. 2. Figure 7 The atomic force microscopy contrast chart is shown in FIG. 2. During the process of observing the perovskite light-absorbing layer 40 of the comparative example and Example 2 by atomic force microscopy, it was found that the introduction of the passivation layer 30 formed by the novel material provided in the embodiments of the present application between the electron transport layer 20 and the perovskite light-absorbing layer 40 of the perovskite solar cell can reduce the surface roughness of the perovskite light-absorbing layer 40. Specifically, during the process of observing the perovskite light-absorbing layer 40 of the comparative example by atomic force microscopy, it was found that the average roughness of the perovskite light-absorbing layer 40 was 27.5 nm, and during the process of observing the perovskite solar cell with the passivation layer 30 formed by the novel material provided in the embodiments of the present application by atomic force microscopy, the average roughness of the perovskite light-absorbing layer 40 of Example 2 was reduced to 24.2 nm.

[0123] The perovskite light-absorbing layers of the comparative example and Example 2 were scanned by scanning electron microscopy, and the scanning electron microscopy contrast chart is shown in FIG. 3. Figure 8 The scanning electron microscopy contrast chart is shown in FIG. 3. By comparing the morphology chart of the perovskite light-absorbing layer of the comparative example and the morphology chart of the perovskite light-absorbing layer 40 of Example 2 obtained by scanning electron microscopy, it can be seen that the introduction of the passivation layer 30 formed by the novel material provided in the embodiments of the present application between the electron transport layer 20 and the perovskite light-absorbing layer 40 of the perovskite solar cell can form large-size perovskite grains in the perovskite light-absorbing layer 40, indicating that the introduction of the passivation layer 30 formed by the novel material provided in the embodiments of the present application between the electron transport layer 20 and the perovskite light-absorbing layer 40 is beneficial to promote the formation of larger perovskite grains.

[0124] The above steps are only used to help understand the method, structure and core idea of the present application. Those skilled in the art can make some improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also belong to the scope of protection of the claims of the present application.

Claims

1. A material for improving perovskite film, characterized in that The molecular structure of the material is shown in general formula (I): General formula (I) Wherein, R1 and R2 are both alkyl groups having 1 to 6 carbon atoms, and R1 and R2 are the same or different.

2. A perovskite solar cell comprising: A substrate (10), an electron transport layer (20), a perovskite light absorbing layer (40), a hole transport layer (50) and a top electrode (60) are stacked in sequence, characterized in that it also includes a passivation layer (30) arranged between the electron transport layer (20) and the perovskite light absorbing layer (40), and the passivation layer (30) is formed based on the material for improving the perovskite film according to claim 1.

3. The perovskite solar cell according to claim 2, characterized in that The passivation layer (30) is formed by coating an organic solution containing the material on the electron transport layer (20).

4. The perovskite solar cell according to claim 3, characterized in that The passivation layer (30) is obtained by the following operations: Applying an organic solution containing the material on the electron transport layer (20) to form a wet organic film; A precursor solution for preparing a perovskite light absorbing layer is coated on a wet organic film, followed by annealing, thereby forming a stacked passivation layer (30) and the perovskite light absorbing layer (40) on the electron transport layer (20).

5. The perovskite solar cell according to claim 4, characterized in that In the organic solution containing the material, the concentration of the material is 0.7-1.3 mg / mL.

6. The method for preparing the material according to claim 1, characterized in that: include: Step A: synthesizing 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene using 1,4-bis(9H-carbazol-9-yl)benzene; Step B: 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)benzene was synthesized using 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazol.

7. The preparation method according to claim 6, characterized in that Step A includes: Step A1, mixing 1,4-bis(9H-carbazol-9-yl)benzene and N-bromosuccinimide to form a mixture; Step A2, adding tetrahydrofuran to the mixture, and controlling the reaction temperature to 95-105° C. and the reaction time to 7-9 h to synthesize 1,4-bis(3,6-dibromo-9H-carbazol-9-yl)benzene; or / and, Step B includes: 1,4-bis(3,6-dibromo-9H-carbazole-9-yl)benzene and 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole were mixed, and a certain amount of carbonate, a compound containing bistriphenylphosphine, and an organic solvent were added. The reaction temperature was controlled at 115-125°C and the reaction time was controlled at 7-9 hours to synthesize 1,4-bis(3,6-bis(4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl)-9H-carbazole-9-yl)benzene.

8. The method for preparing the material according to claim 7, characterized in that: The mass ratio of the 1,4-bis(9H-carbazol-9-yl)benzene to the N-bromosuccinimide is 1:2 to 1:4.5; and / or, The mass volume ratio of the mixture formed in step A1 to the tetrahydrofuran is 1 g:10 mL to 1 g:20 mL.

9. The method for preparing the material according to claim 7, characterized in that: The mass ratio of the 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole to the 1,4-bis(3,6-dibromo-9H-carbazole-9-yl)benzene is 1:1.2 to 1:1.5; and / or, The mass ratio of the bistriphenylphosphine-containing compound, the carbonate, and the 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole is 1:(4.2-4.6):(5.8-6.2); and / or, The mass volume ratio of the 3,6-dialkoxy-9-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)-9H-carbazole to the organic solvent is 1 g:34 mL to 1 g:57 mL.

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