Perovskite solar cell and preparation method thereof

Abstract

The invention belongs to the technical field of photovoltaic materials, and particularly relates to a perovskite solar cell and a preparation method thereof. The perovskite cell comprises a back electrode, a conductive glass substrate, a buffer layer, a hole transport layer, a transport layer and a perovskite layer, the double-sided passivation layer is arranged between the perovskite layer and the hole transport layer; the raw materials of the double-sided passivation layer comprise at least one of benzimidazolethione and derivatives thereof, and benzimidazolone and derivatives thereof. During preparation, the preparation method of the double-sided passivation layer comprises coating. The photoelectric conversion efficiency and the stability of the perovskite solar cell are obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic materials, and in particular relates to a perovskite solar cell and a preparation method thereof. Background Art

[0002] Perovskite solar cells are a new type of solar cell technology and belong to the third generation of solar cells. The core of perovskite solar cells is to use perovskite materials as the photoelectric conversion layer. In theory, the conversion efficiency of solar energy far exceeds that of traditional silicon-based solar cells. Perovskite solar cells are usually divided into three types: mesoporous structure, formal nip planar structure, and trans-pin planar structure. In terms of industrialization, factories are more inclined to choose perovskite cells with lower cost and trans-pin planar structure. Its structure includes transparent conductive layer, hole transport layer, perovskite photoelectric conversion layer, electron transport layer and back electrode in sequence. Light enters the hole transport layer through the transparent conductive layer and then enters the perovskite photoelectric conversion layer. After passing through the photoelectric conversion layer, electrons are transferred to the electron transport layer and finally output electrical energy through the back electrode. However, in the structure of this battery, interface defects are more likely to occur between the hole transport layer and the perovskite photoelectric conversion layer, affecting the stability of the battery. In addition, the connection between the interfaces is not tight enough, which affects the carrier transmission efficiency and has a certain negative effect on the efficiency. Therefore, the efficiency and stability of existing inverse perovskite cells are difficult to meet practical applications, because even if a passivation layer is used, most passivation layers only work on the perovskite layer, and the final effect improvement reflected on the entire component is not optimal. Although there are methods in the prior art to passivate the hole transport layer and the perovskite photoelectric conversion layer to optimize the battery performance, the photoelectric conversion efficiency and stability of the obtained perovskite solar cell still have room for improvement, and the area and process of preparing perovskite solar cells are far from industrialization, and there is a lot of room for improvement. Summary of the invention

[0003] Therefore, the object of the present invention is to provide a perovskite solar cell and a preparation method thereof. The perovskite solar cell uses benzimidazolethione and its derivatives, benzimidazolone and its derivatives as raw materials for a double-sided passivation layer to achieve double-sided passivation of a perovskite layer and a hole transport layer, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0004] To this end, the present invention provides the following technical solutions.

[0005] The present application provides a perovskite solar cell, comprising a back electrode, a conductive glass substrate, a buffer layer, a hole transport layer, a transport layer, and a perovskite layer; further comprising a double-sided passivation layer, which is arranged between the perovskite layer and the hole transport layer; the raw material of the double-sided passivation layer comprises at least one of benzimidazolethione and its derivatives, and benzimidazolone and its derivatives.

[0006] Optionally, the thickness of the double-sided passivation layer is ≥2 nm; optionally, the thickness of the double-sided passivation layer is 5 to 20 nm.

[0007] Optionally, derivatives of benzimidazolethione include 1-ethyl-1H-benzimidazole-2-thione (CAS: 39573-31-4), 5,6-dimethyl-1H-benzimidazole-2-thione, 1,3-dihydro-4,7-dimethyl-2H-benzimidazole-2-thione, 1,3-dimethylbenzimidazole-2-thione (CAS: 3418-46-0), 1-phenyl-1,3-dihydro-benzimidazole-2-thione (CAS: 4493-32-7), 1-isopropyl-1H-benzimidazole-2-thione, 6,7-dimethyl-1H-benzimidazole-2-thione, etc. Some derivatives need to be prepared from relevant precursors when used.

[0008] Optionally, the derivatives of benzimidazolone include 1-ethyl-1H-benzimidazol-2-one, 1,3-dimethylbenzimidazol-2-one, 1-phenyl-1,3-dihydro-benzimidazol-2-one and the like.

[0009] Optionally, the perovskite solar cell includes any one of a formal perovskite solar cell and an inverted perovskite solar cell; optionally, the perovskite solar cell is an inverted perovskite solar cell.

[0010] Optionally, at least one of (1) to (11) is satisfied:

[0011] (1) The material of the back electrode includes at least one of copper, silver and gold;

[0012] (2) The material of the buffer layer includes at least one of zinc oxide, tin oxide, indium oxide, and molybdenum oxide;

[0013] (3) The material of the electron transport layer includes at least one of C60, C70, and fullerene derivatives; optionally, the fullerene derivative includes at least one of [6,6]-phenyl-C61-butyric acid isomethyl ester and [6,6]-phenyl-C7-butyric acid isomethyl ester;

[0014] (4) The material of the perovskite layer includes ABX3 type perovskite; wherein A includes Cs + , Rb + 、MA + , FA + At least one of B including Pb 2+ Sn 2+ At least one of X includes I - Br - , Cl - At least one of;

[0015] (5) The material of the hole transport layer includes at least one of nickel oxide, vanadium oxide, molybdenum oxide, copper oxide, and cobalt oxide; optionally, the material of the hole transport layer includes nickel oxide;

[0016] (6) The material of the conductive glass substrate includes at least one of FTO conductive glass (fluorine-doped SnO2 conductive glass), ITO conductive glass (indium tin oxide conductive glass), AZO conductive glass (aluminum-doped zinc oxide conductive glass), and ATO conductive glass (antimony-doped tin dioxide conductive glass);

[0017] (7) The thickness of the back electrode is 80 to 120 nm;

[0018] (8) The thickness of the buffer layer is 5 to 15 nm;

[0019] (9) The thickness of the electron transport layer is 15 to 25 nm;

[0020] (10) The thickness of the perovskite layer is 400 to 700 nm;

[0021] (11) The thickness of the hole transport layer is 15 to 25 nm.

[0022] The present invention also provides a method for preparing the above-mentioned perovskite solar cell, comprising the following steps: sequentially preparing a hole transport layer, a double-sided passivation layer, a perovskite layer, an electron transport layer, a buffer layer, and a back electrode on the surface of a conductive glass substrate; the preparation method of the double-sided passivation layer comprises coating.

[0023] Optionally, preparing the double-sided passivation layer by a coating method comprises the following steps: coating a double-sided passivation layer raw material solution on the surface of the hole transport layer, and annealing to obtain the double-sided passivation layer.

[0024] Optionally, in the step of preparing the double-sided passivation layer by a coating method, the annealing temperature is 70-120° C., and the annealing time is 1-20 min; optionally, the annealing temperature is 100° C., and the annealing time is 10 min.

[0025] Optionally, the concentration of the double-sided passivation layer raw material solution is 0.5-5 mg / mL; optionally, the concentration of the double-sided passivation layer raw material solution is 2-4 mg / mL; further optionally, the concentration of the double-sided passivation layer raw material solution is 2 mg / mL.

[0026] Optionally, the solvent in the double-sided passivation layer raw material solution includes at least one of ethanol and isopropanol.

[0027] Optionally, in the step of preparing the double-sided passivation layer by a coating method, the coating method includes any one of slit coating and spray coating.

[0028] Optionally, the method for preparing the perovskite layer includes coating a perovskite precursor solution and annealing to obtain the perovskite layer; optionally, the annealing temperature is 120-180° C. and the time is 10-20 min; further optionally, the annealing temperature is 150° C. and the time is 15 min.

[0029] Optionally, the preparation method of the hole transport layer includes magnetron sputtering.

[0030] Optionally, the preparation method of the electron transport layer includes evaporation.

[0031] Optionally, the preparation method of the buffer layer includes evaporation.

[0032] Optionally, the method for preparing the back electrode includes magnetron sputtering.

[0033] Optionally, the step of cleaning the conductive glass substrate is further included before preparing the hole transport layer. Typically, but not limiting, the method for cleaning the conductive glass substrate can be: ultrasonically cleaning the conductive glass substrate with glass cleaning agent, deionized water, ethanol, acetone, isopropanol, and ethanol in sequence, with each liquid cleaning time being 15 to 20 minutes. After the ultrasonic cleaning is completed, the conductive glass substrate is blown dry with nitrogen and treated with ultraviolet-ozone for 15 to 20 minutes.

[0034] Optionally, before preparing the hole transport layer, the step of P1 scratching the conductive glass substrate is also included; after preparing the buffer layer and before preparing the back electrode, the step of P2 scratching is also included; after preparing the back electrode, the step of P3 scratching is also included; optionally, after P3 scratching, the step of P4 edge cleaning is also included.

[0035] The beneficial effects of the present invention are:

[0036] The perovskite solar cell provided by the present invention includes a back electrode, a conductive glass substrate, a buffer layer, a hole transport layer, a transport layer, and a perovskite layer; it also includes a double-sided passivation layer, which is arranged between the perovskite layer and the hole transport layer; the raw materials of the double-sided passivation layer include at least one of benzimidazolethione and its derivatives, benzimidazolone and its derivatives. The photoelectric conversion efficiency and stability of the perovskite solar cell can be significantly improved, the initial photoelectric conversion efficiency can reach more than 16%, and the attenuation of the photoelectric conversion efficiency after being placed for 720 hours is within 18.5%. The benzimidazolethione and its derivatives, benzimidazolone and its derivatives in the double-sided passivation layer contain thione and ketone functional groups, and the S or O on them can react with unsaturated Pb 2+ Sn 2+It forms a strong coordination effect and interacts with the metal ions of the hole transport layer to form a metal ion-S / O-Pb / Sn bridge to enhance hole conductivity and stabilize the structure of the perovskite. In addition, the benzene ring and the benzimidazole ring can combine with the hole transport layer and effectively reduce the defects of the perovskite layer, achieve double-sided passivation, improve the photoelectric conversion efficiency and stability of the components, and are conducive to the industrialization process of perovskite batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of the structure of a perovskite solar cell in an embodiment of the present invention;

[0039] Figure 2 This is an image of the change in the photoelectric conversion efficiency of the perovskite solar cell obtained in Test Example 1 of the present invention over time. DETAILED DESCRIPTION

[0040] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0041] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0042] Example 1

[0043] This embodiment provides a perovskite solar cell and a method for preparing the same. The structural schematic diagram of the prepared perovskite solar cell is shown in FIG. Figure 1 As shown, the specific steps include:

[0044] (1) The FTO conductive glass substrate was scribed with P1, and then ultrasonically cleaned with glass cleaning agent, deionized water, ethanol, acetone, isopropanol, and ethanol in sequence. The cleaning time of each liquid was 15 minutes. After the ultrasonic cleaning, the FTO conductive glass substrate was blown dry with nitrogen and treated with UV-ozone for 15 minutes.

[0045] (2) A nickel oxide hole transport layer with a thickness of 20 nm was magnetron sputtered on the cleaned surface of the FTO conductive glass substrate.

[0046] (3) A 2 mg / mL 1-ethyl-1H-benzimidazole-2-thione ethanol solution was coated on the surface of the hole transport layer by a slit coating method and annealed at 100° C. for 10 min to obtain a double-sided passivation layer with a thickness of 10 nm.

[0047] (4) The perovskite precursor solution was coated on the double-sided passivation layer by slit coating and annealed at 150°C for 15 min to obtain a perovskite layer with a thickness of 500 nm. The perovskite precursor solution used was Cs 0.1 FA 0.9 PbI3, the solvent is a mixed solvent of acetonitrile (ACN), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) in a volume ratio of 0.3:0.65:0.05.

[0048] (5) On the surface of the perovskite layer, C60 with a thickness of 20 nm was sequentially evaporated as an electron transport layer and SnO2 with a thickness of 10 nm was sequentially deposited as a buffer layer, and P2 scratching was performed.

[0049] (6) A Cu layer with a thickness of 100 nm was magnetron sputtered on the surface of the buffer layer as a back electrode, followed by P3 scribing and P4 edge cleaning, and then packaged and stored. The size of the obtained perovskite solar cell is 300 mm × 300 mm.

[0050] Example 2

[0051] This embodiment provides a perovskite solar cell and a method for preparing the same. The only difference from Embodiment 1 is that in step (3), an ethanol solution of 1-ethyl-1H-benzimidazol-2-one is applied.

[0052] Example 3

[0053] This embodiment provides a perovskite solar cell and a method for preparing the same. The only difference from Embodiment 1 is that in step (3), an ethanol solution of 6,7-dimethyl-1H-benzimidazole-2-thione is applied.

[0054] Example 4

[0055] This embodiment provides a perovskite solar cell and a preparation method thereof, which is different from Embodiment 1 only in that step (3) is: coating the surface of the hole transport layer with a 2 mg / mL 1-ethyl-1H-benzimidazole-2-thione ethanol solution by a slit coating method, annealing at 70° C. for 20 min, and obtaining a double-sided passivation layer with a thickness of 10 nm.

[0056] Example 5

[0057] The present embodiment provides a perovskite solar cell and a preparation method thereof, which is different from the embodiment 1 only in that step (3) is: coating the surface of the hole transport layer with a 2 mg / mL 1-ethyl-1H-benzimidazole-2-thione ethanol solution by a slit coating method, annealing at 100° C. for 1 min, and obtaining a double-sided passivation layer with a thickness of 10 nm.

[0058] Example 6

[0059] This embodiment provides a perovskite solar cell and a method for preparing the same. The only difference from Embodiment 1 is that in step (3), the concentration of the ethanol solution of 1-ethyl-1H-benzimidazole-2-thione coated is 0.8 mg / mL.

[0060] Example 7

[0061] This embodiment provides a perovskite solar cell and a method for preparing the same. The only difference from Embodiment 1 is that in step (3), the concentration of the ethanol solution of 1-ethyl-1H-benzimidazole-2-thione coated is 5 mg / mL.

[0062] Example 8

[0063] This embodiment provides a perovskite solar cell and a method for preparing the same. The only difference from Embodiment 1 is that in step (3), the thickness of the double-sided passivation layer obtained is 2 nm.

[0064] Example 9

[0065] This embodiment provides a perovskite solar cell and a method for preparing the same. The only difference from Embodiment 1 is that in step (3), the thickness of the double-sided passivation layer obtained is 30 nm.

[0066] Comparative Example 1

[0067] This comparative example provides a perovskite solar cell and a method for preparing the same, which is different from Example 1 only in that step (3) is not performed, and step (4) is performed directly after step (2).

[0068] Comparative Example 2

[0069] This comparative example provides a perovskite solar cell and a preparation method thereof, which is different from Example 1 only in that in step (3), an ethanol solution of 1-ethylbenzimidazole is applied.

[0070] Test Example 1

[0071] The current-voltage characteristics of the perovskite solar cells obtained in the specific embodiments and comparative examples of the present invention were measured. The test method was as follows: turn on the light source, wait for thirty minutes for the irradiance to reach a stable value, and adjust the irradiance to 1000 W / m 2 . The battery to be tested is placed at the standard battery, and the voltage range, scanning interval voltage, scanning interval time and other parameters are set. The current-voltage characteristics of the battery are measured, and the initial open circuit voltage (Voc), initial short circuit current (Isc), initial fill factor (FF), initial photoelectric conversion efficiency (PCE), and photoelectric conversion efficiency after 720h of placement (PCE720h) of each perovskite solar cell are recorded and calculated. The efficiency decay is calculated again; the test results are shown in Table 1. The photoelectric conversion efficiency of the perovskite solar cells obtained in Example 1, Comparative Example 1, and Comparative Example 2 changes with time, and the data is processed to obtain Figure 2 .

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1, compared with Comparative Example 1 in which no passivation layer exists and Comparative Example 2 in which only an ethanol solution of 1-ethylbenzimidazole is used to make a double-sided passivation layer, the double-sided passivation layer prepared using benzimidazolethione and its derivatives or benzimidazoleketone and its derivatives in the embodiment can effectively improve the efficiency and stability of the perovskite battery, and the thione functional group or ketone functional group thereof plays an important role in improving the efficiency and stability of the perovskite battery. By comparing Examples 1, 4, and 5, it is found that the annealing temperature and annealing time within a reasonable range can effectively improve the battery effect, and the effect is best when the annealing temperature and time are the preferred values. By comparing Examples 1, 6, and 8 with Comparative Example 1, it can be found that when the concentration of the double-sided passivation layer raw material solution is too low or the thickness of the double-sided passivation layer is too thin, the effect of improving the stability of the perovskite battery will be slightly worse. By comparing Examples 1 and 7 with Comparative Example 1, it can be found that when the concentration of the double-sided passivation layer raw material solution is too high, although the perovskite battery has good stability, the initial efficiency will be affected to a certain extent. By comparing Examples 1 and 9 with Comparative Example 1, it can be found that when the double-sided passivation layer is too thick, although the stability is also good, the improvement of the initial efficiency of the perovskite component is not obvious.

[0076] From Table 1 and Figure 2It can be seen that after 720 hours, the conversion efficiency of the perovskite battery provided by the present invention decays slowly as the storage time increases, and the conversion efficiency can still reach more than 90% of the initial conversion efficiency; while the conversion efficiency of comparative example 1 is only about 67% of the initial conversion efficiency, and the conversion efficiency of comparative example 2 is about 75% of the initial conversion efficiency. This proves that in the double-sided passivation layer provided by the present invention, the combination of thioketone and ketone functional groups with benzimidazole can effectively improve the stability of perovskite batteries and help the commercialization of perovskite batteries.

[0077] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A perovskite solar cell, characterized in that: It includes a back electrode, a conductive glass substrate, a buffer layer, a hole transport layer, a transport layer, and a perovskite layer; It also includes a double-sided passivation layer disposed between the perovskite layer and the hole transport layer; The raw material of the double-sided passivation layer includes at least one of benzimidazolethione and its derivatives, and benzimidazolone and its derivatives.

2. The perovskite solar cell according to claim 1, characterized in that The thickness of the double-sided passivation layer is ≥ 2 nm; optionally, the thickness of the double-sided passivation layer is 5 to 20 nm; and / or, derivatives of benzimidazolethione include 1-ethyl-1H-benzimidazole-2-thione, 5,6-dimethyl-1H-benzimidazole-2-thione, 1,3-dihydro-4,7-dimethyl-2H-benzimidazole-2-thione, 1,3-dimethylbenzimidazole-2-thione, 1-phenyl-1,3-dihydro-benzimidazole-2-thione; And / or, the derivatives of benzimidazolone include 1-ethyl-1H-benzimidazol-2-one, 1,3-dimethylbenzimidazol-2-one, 1-phenyl-1,3-dihydro-benzimidazol-2-one.

3. The perovskite solar cell according to claim 1 or 2, characterized in that: The perovskite solar cell includes any one of a formal perovskite solar cell and an inverted perovskite solar cell; optionally, the perovskite solar cell is an inverted perovskite solar cell.

4. The perovskite solar cell according to any one of claims 1 to 3, characterized in that: Satisfy at least one of (1) to (11): (1) The material of the back electrode includes at least one of copper, silver and gold; (2) The material of the buffer layer includes at least one of zinc oxide, tin oxide, indium oxide, and molybdenum oxide; (3) The material of the electron transport layer includes at least one of C60, C70, and fullerene derivatives; optionally, the fullerene derivative includes at least one of [6,6]-phenyl-C61-butyric acid isomethyl ester and [6,6]-phenyl-C7-butyric acid isomethyl ester; (4) The material of the perovskite layer includes ABX3 type perovskite; wherein A includes Cs + , Rb + 、MA + , FA + At least one of B including Pb 2+ Sn 2+ At least one of X includes I - Br - , Cl - At least one of; (5) The material of the hole transport layer includes at least one of nickel oxide, vanadium oxide, molybdenum oxide, copper oxide, and cobalt oxide; optionally, the material of the hole transport layer includes nickel oxide; (6) The material of the conductive glass substrate includes at least one of FTO conductive glass, ITO conductive glass, AZO conductive glass, and ATO conductive glass; (7) The thickness of the back electrode is 80 to 120 nm; (8) The thickness of the buffer layer is 5 to 15 nm; (9) The thickness of the electron transport layer is 15 to 25 nm; (10) The thickness of the perovskite layer is 400 to 700 nm; (11) The thickness of the hole transport layer is 15 to 25 nm.

5. A method for preparing a perovskite solar cell according to any one of claims 1 to 4, characterized in that: The steps include: A hole transport layer, a double-sided passivation layer, a perovskite layer, an electron transport layer, a buffer layer, and a back electrode are sequentially prepared on the surface of a conductive glass substrate; The preparation method of the double-sided passivation layer includes coating.

6. The preparation method according to claim 5, characterized in that: The method of preparing a double-sided passivation layer by coating includes the following steps: A double-sided passivation layer raw material solution is coated on the surface of the hole transport layer, and annealed to obtain the double-sided passivation layer.

7. The preparation method according to claim 6, characterized in that: In the step of preparing the double-sided passivation layer by coating, the annealing temperature is 70-120° C., and the annealing time is 1-20 min; optionally, the annealing temperature is 100° C., and the annealing time is 10 min; And / or, the concentration of the double-sided passivation layer raw material solution is 0.5-5 mg / mL; optionally, the concentration of the double-sided passivation layer raw material solution is 2-4 mg / mL; further optionally, the concentration of the double-sided passivation layer raw material solution is 2 mg / mL; And / or, the solvent in the double-sided passivation layer raw material solution includes at least one of ethanol and isopropanol; And / or, in the step of preparing the double-sided passivation layer by a coating method, the coating method includes any one of slit coating and spray coating.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The method for preparing a perovskite layer comprises coating a perovskite precursor solution, annealing, and obtaining a perovskite layer; optionally, the annealing temperature is 120-180° C., and the time is 10-20 minutes; further optionally, the annealing temperature is 150° C., and the time is 15 minutes.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The preparation method of the hole transport layer includes magnetron sputtering; And / or, the preparation method of the electron transport layer comprises evaporation; And / or, the preparation method of the buffer layer comprises evaporation; And / or, the method for preparing the back electrode comprises magnetron sputtering; And / or, before preparing the hole transport layer, the method further includes a step of cleaning the conductive glass substrate.

10. The preparation method according to any one of claims 5 to 9, characterized in that: Before preparing the hole transport layer, the method further includes the step of P1 scratching the conductive glass substrate; The step of performing P2 scribing after preparing the buffer layer and before preparing the back electrode is also included; After preparing the back electrode, a P3 scribing step is also included; optionally, after P3 scribing, a P4 edge cleaning step is also included.

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