A perovskite solar cell and its preparation method

Abstract

The present invention discloses a perovskite solar cell and a preparation method thereof, comprising a conductive glass layer, a 5-AVA replacement layer, a perovskite layer, a hole transport layer, and an electrode layer, which are sequentially arranged in layers. The carboxyl group of 5-AVA can form a chemical bond with the hydroxyl group on the surface of ITO. Due to the linear structure of 5-AVA itself, the amino group of 5-AVA can effectively face the perovskite layer. The 5-AVA replacement layer does not serve as an electron transport layer, but rather as a dipole layer to modify the surface of the conductive glass layer, thereby reducing the surface work function of the conductive glass layer, making the energy levels between the conductive glass layer and the perovskite layer more matched, greatly suppressing carrier recombination between the conductive glass layer and the perovskite layer, and promoting charge transfer. It also has the effect of improving the crystallization process of the perovskite layer, thereby increasing the grain size of the perovskite layer.

Description

Technical field

[0001] The present invention relates to a perovskite solar cell and a preparation method thereof, and belongs to the field of perovskite solar cells. [Background Technology]

[0002] Traditional perovskite solar cells require the preparation of an electron transport layer as an n-type semiconductor to ensure cell efficiency. The electron transport layer is generally made of oxides such as titanium dioxide or tin dioxide. Regardless of the material used, it must be annealed at high temperatures for a long time to ensure that it forms a suitable crystal form. This process generally requires a temperature above 150°C, especially for titanium dioxide, which can even be annealed at 500°C. For example, tin dioxide not only needs to be annealed at 150°C, but also requires ultraviolet light and ozone for surface treatment. Therefore, the traditional electron transport layer directly leads to the long production process and high energy consumption of existing perovskite solar cells. [Summary of the invention]

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a perovskite solar cell and a preparation method thereof.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A perovskite solar cell comprises a conductive glass layer, a 5-AVA replacement layer, a perovskite layer, a hole transport layer and an electrode layer which are arranged in layers in sequence.

[0006] The beneficial effects of the present invention are:

[0007] The carboxyl group of 5-AVA can form a chemical bond with the hydroxyl group on the surface of ITO. Due to the linear structure of 5-AVA itself, the amino group of 5-AVA can effectively face the perovskite layer. The 5-AVA alternative layer does not serve as an electron transport layer, but as a dipole layer to modify the surface of the conductive glass layer, thereby reducing the surface work function of the conductive glass layer, making the energy levels between the conductive glass layer and the perovskite layer more matched, greatly inhibiting the carrier recombination between the conductive glass layer and the perovskite layer, and promoting charge transfer. It also has the effect of improving the crystallization process of the perovskite layer, thereby increasing the grain size of the perovskite layer.

[0008] The perovskite layer of the present invention is an organic-inorganic hybrid perovskite layer.

[0009] The material of the perovskite layer of the present invention is FA 0.9 Cs 0.1 PbI 3-x Cl x .

[0010] A method for preparing a perovskite solar cell comprises the following steps:

[0011] Step S1: spin-coating an aqueous solution of 5-AVA on the surface of the conductive glass layer, and then annealing at 90-120° C. to form a 5-AVA replacement layer on the surface of the conductive glass layer;

[0012] Step S2: spin-coating an organic-inorganic hybrid perovskite solution on the surface of the 5-AVA replacement layer, and then annealing at 100-150° C. to form an organic-inorganic hybrid perovskite layer on the surface of the 5-AVA replacement layer;

[0013] Step S3: spin-coating a hole transport material solution on the surface of the organic-inorganic hybrid perovskite layer, and then drying and oxidizing the solution in a dryer to form a hole transport layer on the surface of the organic-inorganic hybrid perovskite layer;

[0014] Step S4: preparing an electrode layer on the surface of the hole transport layer.

[0015] The concentration of 5-AVA in the 5-AVA aqueous solution of the present invention is 10-25 mg / mL.

[0016] The organic-inorganic hybrid perovskite solution of the present invention is prepared by dissolving FAI, CsCl and PbI2 in DMF and DMSO and stirring.

[0017] The concentration ratio of FAI, CsCl and PbI2 described in the present invention is 1.26:0.14:1.47.

[0018] Other features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0019] The present invention will be further described below with reference to the accompanying drawings:

[0020] Figure 1 Schematic diagram of the bonding process between 5-AVA and ITO in Examples 1-4 of the present invention.

[0021] Figure 2 These are AFM images of the conductive glass layer in Comparative Example 1 and the 5-AVA replacement layer in Examples 1-4 of the present invention, which correspond to Comparative Example 1, Example 1, Example 2, Example 3 and Example 4 from left to right, respectively.

[0022] Figure 3 Surface potential energy, roughness, and film thickness of the conductive glass layer of Comparative Example 1 and the 5-AVA replacement layer of Comparative Example 2 and Examples 1-4 of the present invention are broken line graphs;

[0023] Figure 4Graphs of water contact angles of the conductive glass layer in Comparative Example 1 and the 5-AVA replacement layers in Examples 1-4 of the present invention, from left to right, correspond to Comparative Example 1, Example 1, Example 2, Example 3, and Example 4, respectively.

[0024] Figure 5 FA in Comparative Example 1 and Examples 1-4 of the present invention 0.9 Cs 0.1 PbI 3-x Cl x The SEM images of the layers, from left to right, correspond to Comparative Example 1, Example 1, Example 2, Example 3 and Example 4, respectively.

[0025] Figure 6 FA in Comparative Example 1 and Examples 1-4 of the present invention 0.9 Cs 0.1 PbI 3-x Cl x XRD pattern of the layer.

[0026] Figure 7 These are the IPCE diagrams of the perovskite solar cells in Comparative Example 1 and Examples 1-4 of the present invention.

[0027] Figure 8 For Comparative Example 1, Example 3 and FA in Comparative Example 3 0.9 Cs 0.1 PbI 3-x Cl x Photograph of layer stability test (25°C, 70% RH).

[0028] Figure 9 For Comparative Example 1, Example 3 and FA in Comparative Example 3 0.9 Cs 0.1 PbI 3-x Cl x Photograph of layer stability test (90°C, 30% RH). [Specific implementation method]

[0029] The following is an explanation and description of the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention. However, the following embodiments are only preferred embodiments of the present invention and are not exhaustive. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0030] In the following description, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate directions or positional relationships are only used to facilitate the description of the embodiments and simplify the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0031] Example 1:

[0032] This embodiment provides a method for preparing a perovskite solar cell, comprising the following steps:

[0033] Step S1: A conductive glass layer (ITO) with a size of 1.5 cm*1.5 cm was cleaned with deionized water, alcohol, and isopropyl alcohol, and then the conductive glass layer was dried. An aqueous solution of 5-AVA (5-aminovaleric acid) was spin-coated on the surface of the conductive glass layer at a spin-coating speed of 4000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes. This not only facilitates the formation of a chemical bond between 5-AVA and the conductive glass layer but also prevents the decomposition of 5-AVA, ultimately forming a 5-AVA replacement layer on the surface of the conductive glass layer.

[0034] In this embodiment, the concentration of 5-AVA in the aqueous solution of 5-AVA is 10 mg / mL;

[0035] Step S2: 1.26 mol FAI, 0.14 mol CsCl and 1.47 mol PbI2 were dissolved in DMF and DMSO and stirred. The volume ratio of DMF to DMSO was 4:1. The stirring temperature was 50 ° C. The mixture was stirred for about 12 hours to form a light yellow organic-inorganic hybrid perovskite solution. The organic-inorganic hybrid perovskite solution was then filtered with a filter with a pore size of 0.22 μm. 30 microliters of the filtered organic-inorganic hybrid perovskite solution was spin-coated on the surface of the 5-AVA replacement layer (first at a spin coating speed of 1000 rpm for 10 seconds, then at a spin coating speed of 6000 rpm for 25 seconds). Chlorobenzene was added dropwise 13 seconds before the end of spin coating. After the spin coating was completed, the mixture was annealed at 110 ° C for 30 minutes to form a FA on the surface of the 5-AVA replacement layer. 0.9 Cs 0.1 PbI 3-x Cl x layer;

[0036] Step S3: 1 mL of spiro-MeOTAD chlorobenzene solution (spiro-MeOTAD concentration is 72.3 mg / mL), 17.5 μL of Li-TFSI acetonitrile solution (Li-TFSI concentration is 520 mg / mL), 28.5 μL of 4-tBP, and 29 μL of FK209 acetonitrile solution (FK209 concentration is 300 mg / mL) are mixed to form a hole transport material solution, and the hole transport material solution is spin-coated onto the surface of the organic-inorganic hybrid perovskite layer at a spin coating speed of 4000 rpm for 30 s. The layer is then transferred to a desiccator for drying and oxidation to form a hole transport layer on the surface of the organic-inorganic hybrid perovskite layer.

[0037] Step S4: Evaporating an 80nm thick silver electrode layer on the surface of the hole transport layer.

[0038] Accordingly, the perovskite solar cell of this embodiment includes a conductive glass layer, a 5-AVA replacement layer, a FA 0.9 Cs 0.1 PbI 3-x Cl x layer, hole transport layer and silver electrode layer.

[0039] Example 2:

[0040] The difference between this embodiment and embodiment 1 is that in step S1, the concentration of 5-AVA in the aqueous solution of 5-AVA is 15 mg / mL.

[0041] Example 3:

[0042] The difference between this embodiment and embodiment 1 is that in step S1, the concentration of 5-AVA in the aqueous solution of 5-AVA is 20 mg / mL.

[0043] Example 4:

[0044] The difference between this embodiment and embodiment 1 is that in step S1, the concentration of 5-AVA in the aqueous solution of 5-AVA is 25 mg / mL.

[0045] Comparative Example 1:

[0046] The difference between this embodiment and embodiment 1 is that step S1 is omitted and FA in step S2 is omitted. 0.9 Cs 0.1 PbI 3-x Cl x The layer is directly prepared on the surface of the conductive glass layer.

[0047] Accordingly, the perovskite solar cell of this embodiment includes a conductive glass layer, a FA layer and a conductive glass layer arranged in layers. 0.9 Cs 0.1 PbI 3-xCl x layer, hole transport layer and silver electrode layer.

[0048] The photoelectric data of the perovskite solar cells in Examples 1-4 and Comparative Example 1 are shown in Table 1.

[0049] Table 1

[0050]

[0051]

[0052] It can be seen that as the concentration of 5-AVA increases, the open circuit voltage Voc, short circuit current density Jsc and fill factor FF of the battery first increase and then decrease. Among them, in Example 3, Voc and FF reach the maximum value, while in Example 2, Jsc reaches the maximum value, but the increase in Jsc is not large, so the battery efficiency PCE in Example 3 reaches the maximum value of 19.37%, which is very close to 20% (battery efficiency using an electron transport layer). The main reason is that, see Figure 1 The carboxyl group of 5-AVA can form a chemical bond with the hydroxyl group on the surface of ITO. Due to the linear structure of 5-AVA itself, the amino group of 5-AVA can effectively face the FA 0.9 Cs 0.1 PbI 3-x Cl x The 5-AVA replacement layer does not act as an electron transport layer, but as a dipole layer to modify the surface of the conductive glass layer, thereby reducing the surface work function of the conductive glass layer, making the conductive glass layer and FA 0.9 Cs 0.1 PbI 3- x Cl x The energy levels between the layers are more matched, which greatly suppresses the conductive glass layer and FA 0.9 Cs 0.1 PbI 3-x Cl x The carrier recombination between layers promotes charge transfer and improves FA 0.9 Cs 0.1 PbI 3-x Cl x The effect of the layer crystallization process, thereby improving FA 0.9 Cs 0.1 PbI 3-x Cl x grain size.

[0053] See also Figure 7It can be seen that compared with Comparative Example 1, Example 3 has a significant improvement in IPCE, which proves that the improvement in Jsc is not caused by experimental error, thus clarifying the improvement effect of 5-AVA on Jsc.

[0054] It is worth noting that 5-AVA is insulating and the 5-AVA alternative layer cannot directly transmit electrons. Since it is only a few nanometers, electrons rely on the quantum tunneling effect to move in the 5-AVA alternative layer. Therefore, as the thickness of the 5-AVA alternative layer increases, the tunneling probability decreases, which leads to a decrease in Jsc in Example 4.

[0055] In Examples 1-4, by limiting the perovskite material to organic-inorganic hybrid perovskite, the annealing temperature is effectively reduced. More importantly, by reducing the annealing temperature of the perovskite material, the decomposition of 5-AVA during the annealing process of the perovskite material is avoided. Figure 6 , it is particularly important to note that, unlike MAPbI3, FA 0.9 Cs 0.1 PbI 3-x Cl x It does not react with 5-AVA, thus preventing 5-AVA from entering FA 0.9 Cs 0.1 PbI 3-x Cl x lattice, so FA 0.9 Cs 0.1 PbI 3-x Cl x There is no stray peak, which confirms the role of 5-AVA in FA 0.9 Cs 0.1 PbI 3-x Cl x The bottom modification effect is more for the improvement of battery performance, rather than for FA 0.9 Cs 0.1 PbI 3-x Cl x Changes in crystal form.

[0056] See also Figure 2 As the 5-AVA concentration increases from 0 to 20 mg / mL, the 5-AVA replacement layer plays a good role in repairing the conductive glass layer, and the surface roughness is significantly reduced. However, when the 5-AVA concentration increases to 25 mg / mL, very obvious local protrusions can be seen ( Figure 2 In other words, an appropriate amount of 5-AVA has a good effect on repairing the surface morphology of the conductive glass layer and can fill the holes on the surface of the conductive glass layer.

[0057] Comparative Example 2:

[0058] In this comparative example, a 5-AVA replacement layer was prepared by the method in Example 3, and then the 5-AVA replacement layer was flushed with 20 mg / mL DMF for 35 seconds to simulate the FA 0.9 Cs 0.1 PbI 3-x Cl x Layer preparation process.

[0059] See also Figure 3 After being washed with DMF, the roughness of the 5-AVA replacement layer in Comparative Example 2 increased compared to that in Example 3. Since 5-AVA is almost insoluble in DMF, it can be judged that the DMF washing process will wash away some 5-AVA. However, the 5-AVA replacement layer in Comparative Example 2 still has a high surface potential energy after being washed with DMF, indicating that even after being washed with DMF, a certain amount of 5-AVA can be retained on the conductive glass layer. This shows that although the 5-AVA replacement layer in Example 3 is only about 4nm thick, it can be removed in the subsequent FA 0.9 Cs 0.1 PbI 3-x Cl x After the layer preparation process is completed, a sufficient amount of it can still remain to reduce the surface work function of the conductive glass layer and improve the FA 0.9 Cs 0.1 PbI 3-x Cl x The effect of grain size.

[0060] See also Figure 4 The water contact angle of the conductive glass layer is 13.4°. As the concentration of 5-AVA increases, the water contact angle of the 5-AVA replacement layer gradually increases. When the 5-AVA concentration is 25 mg / mL, the water contact angle of the 5-AVA replacement layer reaches 28.6°. This is because 5-AVA reduces the hydrophilic hydroxyl groups on the ITO surface. Also, due to the increase in the water contact angle, it effectively reduces the entry of water vapor into the 5-AVA replacement layer and the FA. 0.9 Cs 0.1 PbI 3-x Cl x between layers to enhance FA 0.9 Cs 0.1 PbI 3-x Cl x Humidity stability of the layer.

[0061] See also Figure 5 , although the water contact angle of the 5-AVA replacement layer gradually increases, the FA 0.9 Cs 0.1 PbI 3-x Cl xThe layer still has a good covering effect on the 5-AVA replacement layer, which also shows that the hydrophobicity of the 5-AVA replacement layer will not affect the FA 0.9 Cs 0.1 PbI 3-x Cl x In addition, compared with Comparative Example 1, FA in Example 3 0.9 Cs 0.1 PbI 3-x Cl x The grain size of the layer also increased, which was attributed to the hydrophobicity of the 5-AVA replacement layer reducing the nucleation density and the 5-AVA replacement layer 0.9 Cs 0.1 PbI 3-x Cl x The layer plays a role in inducing growth.

[0062] Since in Examples 1-4 and Comparative Example 1, the FA 0.9 Cs 0.1 PbI 3-x Cl x During the layering process, PbI2 is in excess, and 5-AVA can convert the excess PbI2 from FA 0.9 Cs 0.1 PbI 3-x Cl x The surface of the layer is guided to the FA 0.9 Cs 0.1 PbI 3- x Cl x Bottom of layer.

[0063] Comparative Example 3:

[0064] This comparative example differs from Example 1 in that the 5-AVA replacement layer in step S1 is replaced with a tin dioxide electron transport layer. The preparation method of the tin dioxide electron transport layer can be referred to the applicant's prior patent 202010932606.4 and will not be repeated in this example.

[0065] Under different humidity and temperature conditions, the FA prepared in Comparative Example 1, Example 3 and Comparative Example 3 were 0.9 Cs 0.1 PbI 3-x Cl x Test the stability of the layer.

[0066] Regardless of high humidity or high temperature conditions, MAPbI3 will decompose. However, the difference is that under high temperature conditions, FA 0.9 Cs 0.1 PbI 3-x Clx Mainly decompose, room temperature and high humidity conditions will mainly lead to FA 0.9 Cs 0.1 PbI 3-x Cl x A phase transition occurs, that is, FA 0.9 Cs 0.1 PbI 3-x Cl x The stability of the material includes two aspects: thermal stability and phase stability.

[0067] See also Figure 8 , at 25℃, 70%RH, within the first 9h, FA 0.9 Cs 0.1 PbI 3-x Cl x There is almost no significant change, but at 27h, although the area of the samples in Comparative Example 1, Example 3 and Comparative Example 3 that become transparent is not much different, there are a lot of burrs in the sample in Comparative Example 3, which shows that the tin dioxide electron transport layer has a strong effect on the FA 0.9 Cs 0.1 PbI 3- x Cl x The phase stability of FA is destroyed, but 5-AVA does not affect the 0.9 Cs 0.1 PbI 3-x Cl x That is to say, 5-AVA can destroy the phase stability of FA without destroying it. 0.9 Cs 0.1 PbI 3-x Cl x Based on the phase stability of the cell, the cell efficiency is close to that of perovskite solar cells with an electron transport layer.

[0068] See also Figure 9 , at 90℃, 30%RH, within the first 72h, the FA 0.9 Cs 0.1 PbI 3-x Cl x The thermal stability of the layers is almost the same, FA 0.9 Cs 0.1 PbI 3-x Cl x The layer did not produce obvious decomposition, but between 80h-120h, the yellowing degree between Comparative Example 1 and Example 3 was similar, indicating that the FA in Comparative Example 1 and Example 3 0.9 Cs 0.1 PbI 3-x Clx The decomposition rate of the FA layer is similar. In contrast, the sample in Example 3 quickly turns yellow over a large area, which shows that the tin dioxide electron transport layer has a great influence on the FA 0.9 Cs 0.1 PbI 3-x Cl x The thermal stability of FA also plays a destructive role, and this destructive role is more obvious than the phase stability, indicating that tin dioxide has a negative effect on FA. 0.9 Cs 0.1 PbI 3-x Cl x In other words, 5-AVA can promote the decomposition of FA without destroying it. 0.9 Cs 0.1 PbI 3-x Cl x Based on the thermal stability of the battery, the battery efficiency is close to that of perovskite solar cells with an electron transport layer.

[0069] In other words, the 5-AVA replacement layer can be used as an alternative to the electron transport layer, which will not only not significantly reduce the battery efficiency, but also greatly improve the FA 0.9 Cs 0.1 PbI 3-x Cl x Thermal stability and phase stability of materials.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art will understand that the present invention includes, but is not limited to, the contents described in the drawings and the above specific embodiments. Any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A perovskite solar cell, characterized in that: It includes a conductive glass layer, a 5-AVA replacement layer, a perovskite layer, a hole transport layer and an electrode layer arranged in layers in sequence, wherein the material of the perovskite layer is FA 0.9 Cs 0.1 PbI 3-x Cl x .

2. A method for preparing a perovskite solar cell, characterized in that: The steps include: Step S1: spin-coating an aqueous solution of 5-AVA on the surface of the conductive glass layer, and then annealing at 90-120° C. to form a 5-AVA replacement layer on the surface of the conductive glass layer; Step S2: spin-coating an organic-inorganic hybrid perovskite solution on the surface of the 5-AVA replacement layer, and then annealing at 100-150° C. to form an organic-inorganic hybrid perovskite layer on the surface of the 5-AVA replacement layer; Step S3: spin-coating a hole transport material solution on the surface of the organic-inorganic hybrid perovskite layer, and then drying and oxidizing the solution in a dryer to form a hole transport layer on the surface of the organic-inorganic hybrid perovskite layer; Step S4: preparing an electrode layer on the surface of the hole transport layer.

3. The method for preparing a perovskite solar cell according to claim 2, wherein: The concentration of 5-AVA in the aqueous solution of 5-AVA is 10-25 mg / mL.

4. The method for preparing a perovskite solar cell according to claim 2, wherein: The preparation method of the organic-inorganic hybrid perovskite solution is as follows: dissolve FAI, CsCl and PbI2 in DMF and DMSO and stir.

5. The method for preparing a perovskite solar cell according to claim 4, wherein: The concentration ratio of FAI, CsCl and PbI2 is 1.26:0.14:1.47.

Images