Hole transport layer and preparation method thereof, and perovskite solar cell

Abstract

The invention discloses a hole transport layer and a preparation method thereof, and a perovskite solar cell, and belongs to the technical field of perovskite solar cells. The hole transport layer in the battery comprises a self-assembled monomolecular matrix layer and a self-assembled monomolecular filling layer filled in gaps of the self-assembled monomolecular matrix layer, and the molecular size of the material of the self-assembled monomolecular filling layer is smaller than that of the material of the self-assembled monomolecular matrix layer. According to the method, a solution of a layer of self-assembled monomolecular matrix layer material is formed, and a self-assembled monomolecular matrix layer is obtained through primary annealing; and forming a solution of a layer of self-assembled monomolecular filling layer material, and carrying out secondary annealing to obtain the self-assembled monomolecular filling layer. Based on a self-assembled monomolecular matrix layer and a self-assembled monomolecular filling layer filled in gaps of the self-assembled monomolecular matrix layer, the problem that the conversion efficiency of a perovskite solar cell is low due to the fact that an existing hole transport layer has many surface defects and a substrate is not completely covered is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cells, and particularly relates to a hole transport layer, a preparation method thereof, and a perovskite solar cell. Background Art

[0002] Perovskite solar cells are the third-generation new photovoltaic materials, which have the characteristics of simple preparation process, large spectral absorption range, and low cost. The hole transport layer in perovskite solar cells is one of the key film layers.

[0003] Currently, an inorganic hole transport layer (for example, NiO) or a single-layer self-assembled monolayer is usually used as the hole transport layer.

[0004] Among them, the inorganic hole transport layer is formed by magnetron sputtering or spin coating method. However, it has many surface defects, the selectivity of the inorganic hole transport layer is limited, and it is partially incompatible with the solution method for forming the perovskite light-absorbing layer; the single-layer self-assembled monolayer is formed by spin coating method or by immersing the substrate in the self-assembled monolayer solution. However, the single-layer self-assembled molecules do not completely cover the substrate, and there is an energy level mismatch with the perovskite.

[0005] In summary, the above two hole transport layers will both result in low photoelectric conversion efficiency of perovskite solar cells. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a hole transport layer, a preparation method thereof, and a perovskite solar cell, so as to solve the problem of low photoelectric conversion efficiency of perovskite solar cells caused by many surface defects of the hole transport layer and incomplete coverage of the substrate.

[0007] The object of the present invention is mainly achieved by the following technical solutions.

[0008] In the first aspect of the present invention, a hole transport layer is provided, which includes a self-assembled monolayer matrix layer and a self-assembled monolayer filling layer filled in the voids of the self-assembled monolayer matrix layer, and the molecular size of the material of the self-assembled monolayer filling layer is smaller than the molecular size of the material of the self-assembled monolayer matrix layer.

[0009] Further, the self-assembled monolayer matrix layer material is one or more of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid, (4-(9H-carbazol-9-yl)butyl)phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, 4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazol-7-yl)butylphosphonic acid, mixed in any proportion; and / or, the self-assembled monolayer filling layer material is one or more of (2-(9H-carbazol-9-yl)ethyl)phosphonic acid, (2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl)phosphonic acid, 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, mixed in any proportion.

[0010] Further, the hole transport layer is a single-layer structure.

[0011] Further, the mass ratio of the self-assembled monolayer matrix layer material to the self-assembled monolayer filling layer material is 1:2 to 1:4.8.

[0012] The second aspect of the present invention provides a preparation method of a hole transport layer for preparing the hole transport layer provided in the first aspect. The preparation method includes the following steps:

[0013] Step a: Form a solution of a self-assembled monolayer matrix layer material on the surface of the substrate;

[0014] Step b: Anneal the substrate with the solution of the self-assembled monolayer matrix layer material once to obtain a self-assembled monolayer matrix layer, and there are voids in the self-assembled monolayer matrix layer;

[0015] Step c: Form a solution of a self-assembled monolayer filling layer material on the surface of the self-assembled monolayer matrix layer, and part of the solution of the self-assembled monolayer filling layer material fills into the voids;

[0016] Step d: Anneal the substrate with the solution of the self-assembled monolayer filling layer material a second time to obtain a self-assembled monolayer filling layer.

[0017] Further, the solution concentration of the self-assembled monolayer filling layer material is greater than the solution concentration of the self-assembled monolayer matrix layer material.

[0018] Further, in step a, the solution concentration of the self-assembled monolayer matrix layer material is 0.3 to 1.1 mg / mL; and / or, in step c, the solution concentration of the self-assembled monolayer filling layer material is 1.15 to 3 mg / mL.

[0019] Further, the volume ratio of the solution of the self-assembled monolayer matrix layer material to the solution of the self-assembled monolayer filling layer material is 55 to 70:68 to 75.

[0020] Further, after step d, the following steps are further included:

[0021] Step e: Clean the surface of the hole transport layer to remove the self-assembled monolayer filling layer material that is not anchored to the substrate.

[0022] The third aspect of the present invention provides a perovskite solar cell, including the hole transport layer provided by the first aspect.

[0023] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0024] A) For the hole transport layer provided by the present invention, the self-assembled monolayer matrix layer is a continuous structure. During the formation process, the hydroxyl groups in the self-assembled monolayer matrix layer material will anchor to the substrate of the perovskite solar cell, but voids will also be generated, resulting in incomplete coverage of the substrate. It should be noted that the size of the voids is smaller than the molecular size of the self-assembled monolayer matrix layer material and larger than the molecular size of the self-assembled monolayer filling layer material. The self-assembled monolayer matrix layer is a non-continuous structure. Since the molecular size of the self-assembled monolayer filling layer material is smaller than the molecular size of the self-assembled monolayer matrix layer material, the molecules of the self-assembled monolayer filling layer material can enter the voids and anchor to the substrate of the perovskite solar cell, filling the voids, thereby improving the coverage rate of the hole transport layer on the substrate, regulating the work function and energy level, and improving the energy level mismatch problem between the hole transport layer and the perovskite light-absorbing layer of the perovskite solar cell, and further effectively improving the open-circuit voltage, fill factor, energy conversion efficiency, and repeatability of the perovskite solar cell.

[0025] B) For the hole transport layer provided by the present invention, since a relatively complete hole transport layer is formed, it can provide a good surface for the subsequent formation of the perovskite light-absorbing layer, which is beneficial to improving the quality of the perovskite light-absorbing layer.

[0026] C) For the hole transport layer provided by the present invention, a single-layer hole transport layer is formed by using two materials. Compared with the hole transport layer with a multi-layer composite structure, its interface resistance is smaller, which is more conducive to improving the photoelectric conversion efficiency of the subsequent perovskite solar cell.

[0027] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the embodiments of the specification and the drawings. Description of the Drawings

[0028] The accompanying drawings are only for the purpose of showing specific embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference numerals denote the same components.

[0029] Figure 1 It is a schematic diagram of the self-assembled monolayer filling layer filling the voids of the self-assembled monolayer matrix layer in the hole transport layer provided by the present invention;

[0030] Figure 2 It is a schematic structural diagram of the perovskite single-junction battery provided by the present invention;

[0031] Figure 3 It is a schematic structural diagram of the perovskite-silicon tandem battery provided by the present invention;

[0032] Figure 4 It is an X-ray photoelectron spectroscopy test diagram of the substrate in step 1 of Example 1 of the present invention;

[0033] Figure 5a It is an X-ray photoelectron spectroscopy test diagram of the stacked structure obtained in step 2 of Example 1 of the present invention;

[0034] Figure 5b It is an X-ray photoelectron spectroscopy test diagram of the stacked structure obtained in step 3 of Example 1 of the present invention;

[0035] Figure 6a It is an energy-dispersive spectrometer analysis test diagram of the C element of the stacked structure obtained in step 2 of Example 1 of the present invention;

[0036] Figure 6b It is an energy-dispersive spectrometer analysis test diagram of the N element of the stacked structure obtained in step 2 of Example 1 of the present invention;

[0037] Figure 6c It is an energy-dispersive spectrometer analysis test diagram of the P element of the stacked structure obtained in step 2 of Example 1 of the present invention;

[0038] Figure 7a It is an energy-dispersive spectrometer analysis test diagram of the C element of the stacked structure obtained in step 3 of Example 1 of the present invention;

[0039] Figure 7b It is an energy-dispersive spectrometer analysis test diagram of the N element of the stacked structure obtained in step 3 of Example 1 of the present invention;

[0040] Figure 7c It is an energy-dispersive spectrometer analysis test diagram of the P element of the stacked structure obtained in step 3 of Example 1 of the present invention.

[0041] Reference numerals:

[0042] 1 - Substrate; 2 - Hole transport layer; 3 - Perovskite light - absorbing layer; 4 - Electron transport layer; 5 - Buffer layer; 6 - Front recombination layer; 7 - Positive electrode; 8 - Back electrode; 9 - Anti - reflection layer. Detailed implementation manners

[0043] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0044] In the first aspect of the present invention, a hole transport layer is provided. Refer to Figure 1 , which includes a self - assembled monolayer matrix layer and a self - assembled monolayer filling layer filled in the voids of the self - assembled monolayer matrix layer. The molecular size of the self - assembled monolayer filling layer material is smaller than that of the self - assembled monolayer matrix layer material.

[0045] Compared with the prior art, for the hole transport layer provided by the present invention, on the one hand, the self - assembled monolayer matrix layer is a continuous structure. During the formation process, the hydroxyl groups in the self - assembled monolayer matrix layer material will anchor to the substrate of the perovskite solar cell, but voids will also be generated, resulting in incomplete coverage of the substrate. It should be noted that the size of the voids is smaller than the molecular size of the self - assembled monolayer matrix layer material and larger than the molecular size of the self - assembled monolayer filling layer material. The self - assembled monolayer matrix layer is a non - continuous structure. Since the molecular size of the self - assembled monolayer filling layer material is smaller than that of the self - assembled monolayer matrix layer material, the molecules of the self - assembled monolayer filling layer material can enter the voids and anchor to the substrate of the perovskite solar cell, filling the voids. Thus, the coverage rate of the hole transport layer on the substrate can be improved, the work function and energy level can be regulated, and the energy level mismatch problem between the hole transport layer and the perovskite light - absorbing layer of the perovskite solar cell can be improved. Furthermore, the open - circuit voltage, fill factor, energy conversion efficiency, and repeatability of the perovskite solar cell can be effectively improved.

[0046] On the other hand, since a relatively complete hole transport layer is formed, it can provide a good surface for the subsequent formation of the perovskite light - absorbing layer, which is beneficial to improving the quality of the perovskite light - absorbing layer.

[0047] On yet another hand, using two materials to form a single - layer hole transport layer, compared with the hole transport layer with a multi - layer composite structure, its interface resistance is smaller, which is more conducive to improving the photoelectric conversion efficiency of the subsequent perovskite solar cell.

[0048] Exemplarily, the self-assembled monolayer matrix layer material is one or more of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB), (4-(9H-carbazol-9-yl)butyl)phosphonic acid (4PACz), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), 4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazol-7-yl)butylphosphonic acid (MeO-4PADBC), mixed in any proportion.

[0049] The self-assembled monolayer filling layer material is one or more of (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl)phosphonic acid (Ph-2PACz), 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), mixed in any proportion.

[0050] In a second aspect, the present invention provides a method for preparing a hole transport layer for preparing the hole transport layer provided in the first aspect. The preparation method includes the following steps:

[0051] Step a: Form (for example, by spin coating) a solution of a self-assembled monolayer matrix layer material on the surface of the substrate;

[0052] Step b: Anneal the substrate with the solution of the self-assembled monolayer matrix layer material once to evaporate the solvent in the solution, so that the hydroxyl groups of the self-assembled monolayer matrix layer material molecules are anchored to the substrate, obtaining a self-assembled monolayer matrix layer with voids therein;

[0053] Step c: Form (for example, by spin coating) a solution of a self-assembled monolayer filling layer material on the surface of the self-assembled monolayer matrix layer, and part of the solution of the self-assembled monolayer filling layer material fills into the voids;

[0054] Step d: Anneal the substrate with the solution of the self-assembled monolayer filling layer material a second time to evaporate the solvent in the solution, so that the hydroxyl groups of the self-assembled monolayer filling layer material molecules filled into the voids are anchored to the substrate exposed in the voids of the self-assembled monolayer matrix layer, obtaining a self-assembled monolayer filling layer.

[0055] Compared with the prior art, the beneficial effects of the method for preparing a hole transport layer provided by the present invention are basically the same as those of the hole transport layer provided in the first aspect, and will not be elaborated one by one here.

[0056] In order to better fill the voids in the self-assembled monolayer matrix layer, the solution concentration of the above-mentioned self-assembled monolayer filling layer material is greater than that of the self-assembled monolayer matrix layer material. In this way, after the formation of the self-assembled monolayer matrix layer, the solution of the high-concentration self-assembled monolayer filling layer material can better fill the voids in the self-assembled monolayer matrix layer, further improving the coverage rate of the hole transport layer on the substrate.

[0057] Exemplarily, in the above step a, the solution concentration of the self-assembled monolayer matrix layer material is 0.3 - 1.1 mg / mL, and in the above step c, the solution concentration of the self-assembled monolayer filling layer material is 1.15 - 3 mg / mL. This is because when the solution concentration of the self-assembled monolayer matrix layer material is relatively low, it can ensure the formation of a single-layer self-assembled monolayer matrix layer, avoiding excessive self-assembled monolayer matrix layer material that cannot be anchored to the substrate, resulting in an increase in the interfacial resistance of the hole transport layer and affecting the photoelectric conversion efficiency of the subsequent perovskite solar cell; in addition, when the solution concentration of the self-assembled monolayer filling layer material is relatively high, it can fully fill the voids in the self-assembled monolayer matrix layer, improving the coverage rate of the hole transport layer on the substrate.

[0058] Correspondingly, the volume ratio of the solution of the self-assembled monolayer matrix layer material to the solution of the self-assembled monolayer filling layer material is 55 - 70:68 - 75.

[0059] It should be noted that when using a solution of a high-concentration self-assembled monolayer filling layer material, there will inevitably be residual self-assembled monolayer filling layer material that is not anchored to the substrate, affecting the interfacial resistance of the hole transport layer. Therefore, after the above step d, the following steps are further included:

[0060] Step e: Clean the surface of the hole transport layer with an organic solvent to remove the self-assembled monolayer filling layer material that is not anchored to the substrate.

[0061] Exemplarily, the organic solvent is one or a mixture of any proportion of ethanol, butanol, chlorobenzene, dimethyl sulfoxide, isopropanol.

[0062] In order to ensure the spin coating uniformity and spin coating efficiency of the solution of the self-assembled monolayer matrix layer material, in the above step a, the spin coating speed is 2800 - 3200 rpm, the spin coating acceleration is 2800 - 3200 rpm / s, and the spin coating time is 25 - 35 s.

[0063] Correspondingly, in order to ensure the spin coating uniformity and spin coating efficiency of the solution of the self-assembled monolayer filling layer material, in the above step c, the spin coating speed is 2800 - 3200 rpm, the spin coating acceleration is 2800 - 3200 rpm / s, and the spin coating time is 25 - 35 s.

[0064] In order to achieve sufficient annealing, in step b above, the primary annealing temperature is 95 - 100 °C and the primary annealing time is 10 - 12 min.

[0065] Correspondingly, in step d above, the secondary annealing temperature is 95 - 100 °C and the secondary annealing time is 10 - 12 min.

[0066] In a third aspect, the present invention provides a perovskite solar cell, including the hole transport layer provided in the first aspect.

[0067] Compared with the prior art, the beneficial effects of the perovskite solar cell provided by the present invention are basically the same as those of the hole transport layer provided in the first aspect, and will not be elaborated here one by one.

[0068] It should be noted that based on different types of substrates of the perovskite solar cell, the specific structure of the above perovskite solar cell is as follows:

[0069] When the substrate 1 is a glass substrate, the perovskite solar cell is a perovskite single - junction cell, see Figure 2 , including a glass substrate and, successively stacked on the light - receiving surface of the glass substrate, a hole transport layer 2, a perovskite light - absorbing layer 3, an electron transport layer 4, and a positive electrode 7. The hole transport layer 2 is the hole transport layer provided in the first aspect.

[0070] When the substrate 1 is a conductive silicon substrate, the perovskite solar cell is a perovskite - silicon tandem cell. For the structure of the perovskite - silicon tandem cell, see Figure 3 , including a conductive silicon substrate, a hole transport layer 2, a perovskite light - absorbing layer 3, an electron transport layer 4, a buffer layer 5, a front surface recombination layer 6, and a positive electrode 7 successively stacked on the light - receiving surface of the conductive silicon substrate, an antireflection layer 9 provided on the surface of the front surface recombination layer 6 and located between two positive electrodes 7, and a back electrode 8 formed on the backlight surface of the conductive silicon substrate.

[0071] It should be noted that the preparation method of the above perovskite solar cell includes the following steps:

[0072] Provide a substrate 1;

[0073] Form a hole transport layer 2 on the surface of the substrate 1.

[0074] It should be noted that the formation method of the above hole transport layer 2 adopts the preparation method of the hole transport layer provided in the second aspect.

[0075] For the perovskite single - junction cell, the preparation method includes the following steps:

[0076] Step A: Provide a glass substrate;

[0077] Step B: A hole transport layer 2, a perovskite light-absorbing layer 3, an electron transport layer 4, and a positive electrode 7 (e.g., an Au electrode or an Ag electrode) are sequentially formed on the surface of the glass substrate to obtain a perovskite solar cell.

[0078] For the perovskite / silicon tandem cell, the preparation method includes the following steps:

[0079] Step A': Provide a conductive silicon substrate;

[0080] Step B': A hole transport layer 2, a perovskite light-absorbing layer 3, an electron transport layer 4, a buffer layer 5, a front surface recombination layer 6, and a positive electrode 7 (e.g., an Ag electrode) are sequentially formed on the surface of the conductive silicon substrate;

[0081] Step C': An antireflection layer 9 is formed on the surface of the front surface recombination layer 6 between the two positive electrodes 7, and a back electrode 8 is formed on the backlight surface of the conductive silicon substrate to obtain a perovskite solar cell.

[0082] Specifically, the formation methods of the above layers are as follows:

[0083] For the formation method of the perovskite light-absorbing layer 3, it includes the following steps:

[0084] The stacked structure obtained in the previous step is placed in a mask template of the perovskite light-absorbing layer 3, and the mask template is placed in a vacuum evaporation device to evaporate cesium bromide and lead iodide to form an inorganic framework. The thickness of the inorganic framework is 200 - 300 nm, and the evaporation rate of cesium bromide is The evaporation rate of lead iodide is The vacuum degree is 4.5 - 5.5×10 - 4 Pa;

[0085] The perovskite precursor raw materials are stirred and mixed to obtain a perovskite precursor solution. Among them, the composition of the perovskite precursor raw materials includes A-site cation compounds and organic solvents. The stirring temperature is 20 - 30 °C, and the stirring time is 0.5 - 1.0 h;

[0086] Exemplarily, the A-site cation compound is one or more of methylammonium iodide (FAI), methylammonium bromide (FABr), methylammonium chloride (FACl), methylammonium iodide (MAI), methylammonium bromide (MABr), methylammonium chloride (MACl), butylammonium iodide (BAI), butylammonium bromide (BABr), and butylammonium chloride (BACl) in any proportion; the organic solvent is one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ethanol, and propanol in any proportion.

[0087] The precursor solution is spin-coated onto the surface of the inorganic framework. The spin-coating speed is 3000 - 4000 rpm, the spin-coating acceleration is 3000 - 4000 rpm / s, and the spin-coating time is 28 - 33 s.

[0088] The substrate 1 spin-coated with the precursor solution is transferred to a heating stage for heat annealing to obtain the perovskite light-absorbing layer 3. Among them, the humidity for heat annealing is 52 - 62%, the temperature for heat annealing is 150 - 170 °C, the time for heat annealing is 25 - 40 min, and the thickness of the perovskite light-absorbing layer 3 is 350 - 500 nm.

[0089] For the formation method of the electron transport layer 4, it includes the following steps:

[0090] The laminated structure obtained in the previous step is placed in the mask template of the electron transport layer 4, and a lithium fluoride layer (LiF layer) and a graphene layer (C 60 layer) are sequentially deposited on the surface of the perovskite light-absorbing layer 3. Additionally, a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline layer (BCP layer) can be deposited on the surface of the graphene layer (C60 layer). The deposition rate of the lithium fluoride layer is The deposition rate of the graphene layer is The deposition rate of the 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline layer is The vacuum degree is 4.5 - 5.5×10 -4 Pa. The thickness of the lithium fluoride layer is 0.8 - 1.2 nm, the thickness of the graphene layer is 8 - 12 nm, and the thickness of the 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline layer is 1.3 - 1.5 nm.

[0091] For the formation method of the buffer layer 5, it includes the following steps:

[0092] The laminated structure obtained in the previous step is placed in the chamber of atomic layer deposition to deposit the buffer layer 5 on the surface of the electron transport layer 4. Among them, the vacuum degree is 20 - 25 Pa, the deposition temperature is 150 - 155 °C, the pressure of the water source is 45 - 50 Pa, the pressure of the tin source is 20 - 25 Pa, and the number of cycles is 85 - 100 times.

[0093] For the formation method of the front composite layer 6, it includes the following steps:

[0094] The laminated structure obtained in the previous step is placed in the mask template of the front composite layer 6, and the front composite layer 6 is sputtered (for example, DC magnetron sputtering) on the surface of the buffer layer 5. The substrate temperature for sputtering is 60 - 63 °C, and the pressure in the sputtering chamber is 9.0 - 9.2×10 -4Pa, the argon flow rate is 7 - 8 sccm, the oxygen flow rate is 7 - 8 sccm, the sputtering intensity is 185 - 200 W, and the sputtering time is 2.5 - 4 min.

[0095] For the formation method of the positive electrode 7 and the back electrode 8, it includes the following steps:

[0096] Place the laminated structure obtained in the previous step into the mask templates of the positive electrode 7 and / or the back electrode 8 respectively, and then place the mask templates into a vacuum deposition device to prepare the positive electrode 7 and / or the back electrode 8. Among them, the vacuum degree is 6 - 8×10 -4 Pa, and the deposition rate is The thickness of the positive electrode 7 is 120 - 400 nm, and the thickness of the back electrode 8 is 150 - 200 nm.

[0097] It should be noted that for the perovskite single - junction cell, the thickness of the positive electrode 7 is 120 - 150 nm, and for the perovskite - silicon tandem cell, the thickness of the positive electrode 7 is 350 - 400 nm.

[0098] For the formation method of the antireflection layer 9, it includes the following steps:

[0099] Place the laminated structure obtained in the previous step on the mask template, and then place the mask template into a vacuum deposition device to prepare the antireflection layer 9. The vacuum degree is 10.0 - 10.3×10 -4 Pa, and the thickness is 100 - 105 nm.

[0100] Example 1

[0101] The preparation method of the perovskite single - junction cell in this example includes the following steps:

[0102] Step 1: Place the 1.5×1.5 cm 2 substrate (ITO glass substrate) into acetone and absolute ethanol respectively for ultrasonic cleaning for 20 min. Then dry the substrate with nitrogen and place it in ozone for treatment for 30 min;

[0103] Step 2: Transfer the substrate to a spin coater in a nitrogen glove box, spin - coat a layer of 4PADCB solution on the substrate surface. The amount of the 4PADCB solution is 60 uL, the concentration is 0.5 mg / mL, the spin - coating speed is 3000 rpm, the acceleration is 3000 rpm / s, and it lasts for 30 s. After annealing the substrate spin - coated with the 4PADCB solution on a hot stage at 100 °C for 10 min, a 4PADCB layer is obtained;

[0104] Step 3: Spin-coat a layer of 2PACz solution on the surface of the 4PADCB layer. Part of the 2PACz solution fills the voids in the 4PADCB layer. The amount of the 2PACz solution used is 70 μL, the concentration is 1.5 mg / mL, the spin-coating speed is 3000 rpm, the acceleration is 3000 rpm / s, and it lasts for 30 s. After placing the substrate spin-coated with the 2PACz solution on a hot plate and annealing it at 100 °C for 10 min, a 2PACz layer is obtained. After completing the preparation of the hole transport layer, the hole transport layer is cleaned with absolute ethanol;

[0105] Step 4: Place the structure obtained in Step 3 in a mask template for the perovskite light-absorbing layer. Place the mask template in a vacuum evaporation device and evacuate to 5×10 -4 Pa, and adjust the rate of cesium bromide to the rate of lead iodide to Evaporate cesium bromide and lead iodide to form an inorganic framework with a thickness of 200 nm;

[0106] Step 5: Weigh 51.59 mg of FAI, 18.75 mg of FABr, 5.7 mg of MACl, and 12.6 mg of MABr and dissolve them in 1 mL of absolute ethanol. Stir them at 25 °C for 0.5 h to obtain a perovskite precursor solution;

[0107] Step 6: Spin-coat 75 μL of the precursor solution onto the surface of the inorganic framework by spin-coating. The spin-coating speed is 3000 rpm, the spin-coating acceleration is 3000 rpm / s, and the spin-coating time is 30 s. Then, transfer the substrate to a heating plate and perform heating annealing at an ambient humidity of 52% and a temperature of 150 °C for 30 min to obtain a perovskite light-absorbing layer with a thickness of 350 nm;

[0108] Step 7: Place the structure obtained in Step 6 in a mask template for the electron transport layer. Place the mask template in a vacuum deposition device and evacuate to 5×10 -4 Pa, and then evaporate LiF, C60, and BCP. The deposition rates are with thicknesses of 1 nm, 10 nm, and 1.5 nm respectively;

[0109] Step 8: Place the structure obtained in Step 7 in a mask template for silver evaporation. Then, place the mask template in a vacuum deposition device and evacuate to 8×10 -4 Pa and perform silver electrode evaporation at a rate of with a thickness of 120 nm to complete the preparation of the perovskite single-junction solar cell.

[0110] Perform X-ray photoelectron spectroscopy (XPS) tests on the substrate in Step 1, the stacked structure obtained in Step 2, and the bottom structure obtained in Step 3, see Figure 4 、Figure 5a and Figure 5b . By comparing Figure 4 and Figure 5a it can be seen that no N1s and P2p characteristic peaks appear in the XPS full-spectrum peaks of the substrate, while N1s and P2p characteristic peaks appear in the XPS full-spectrum peak pattern of the stacked structure, indicating that the 4PADCB layer is successfully anchored and assembled on the substrate; by comparing Figure 5a and Figure 5b it can be seen that Figure 5b shows N1s and P2p characteristic peaks and the peak intensities of the characteristic peaks are higher, indicating that the 2PACz layer enhances the coverage of the hole transport layer on the substrate.

[0111] Energy Dispersive Spectrometer (EDS) tests were respectively carried out on the stacked structure obtained in Step 2 and the stacked structure obtained in Step 3. Among them, Figures 6a to 6c is the test diagram of the stacked structure obtained in Step 2, Figures 7a to 7c is the test diagram of the stacked structure obtained in Step 3. By comparison, it can be seen that Figures 6a to 6c has lower contents of C, N and P elements, indicating that the coverage rate of the 4PADCB layer on the substrate is lower and part of the substrate is still not covered, Figures 7a to 7c the contents of C, N and P elements are significantly increased, indicating that the addition of the 2-PACz layer fills the places not covered by the 4PADCB layer and enhances the coverage rate of the hole transport layer on the substrate.

[0112] Example 2

[0113] The perovskite single-junction battery of this example is prepared by the following steps:

[0114] Step 1: Place the substrate (ITO glass substrate) of 1.5×1.5 cm 2 in acetone and absolute ethanol respectively for ultrasonic cleaning for 25 min, then dry the substrate with nitrogen and place it in ozone for treatment for 25 min;

[0115] Step 2: Transfer the substrate to a spin coater in a nitrogen glove box, spin coat a layer of 4PACz solution on the substrate surface, the dosage of the 4PACz solution is 55 uL, the concentration is 0.3 mg / mL, the spin coating speed is 2800 rpm, the acceleration is 2800 rpm / s, and it lasts for 35 s. After annealing the substrate spin coated with the 4PACz solution on a hot stage at 95 °C for 12 min, a 4PACz layer is obtained;

[0116] Step 3: Spin-coat a layer of Ph-2PACz solution on the surface of the 4PACz layer. Part of the Ph-2PACz solution fills the voids in the 4PACz layer. The amount of the Ph-2PACz solution used is 68 uL, the concentration is 1.15 mg / mL, the spin-coating speed is 2800 rpm, the acceleration is 2800 rpm / s, and it lasts for 35 s. After placing the substrate spin-coated with the Ph-2PACz solution on a hot plate and annealing it at 95 °C for 12 min, a Ph-2PACz layer is obtained, and the preparation of the hole transport layer is completed;

[0117] Step 4: Place the structure obtained in Step 3 in a mask template for the perovskite light-absorbing layer, and place the mask template in a vacuum evaporation device. Evacuate to 4.5×10 -4 Pa, and adjust the rate of cesium bromide to be The rate of lead iodide is Evaporate cesium bromide and lead iodide to form an inorganic framework, and the thickness of the inorganic framework is 250 nm;

[0118] Step 5: Weigh 50.61 mg of FACl, 19.50 mg of FABr, 5.9 mg of MAI, and 11.4 mg of BABr and dissolve them in 1 mL of DMSO. Stir with shaking at 20 °C for 1.0 h to obtain a perovskite precursor solution;

[0119] Step 6: Spin-coat 70 uL of the precursor solution onto the surface of the inorganic framework by spin-coating. The spin-coating speed is 3500 rpm, the spin-coating acceleration is 3500 rpm / s, and the spin-coating time is 33 s. Then, transfer the substrate to a heating table and perform heating annealing at an ambient humidity of 55% and a temperature of 155 °C for 40 min to obtain a perovskite light-absorbing layer, and the thickness of the perovskite light-absorbing layer is 400 nm;

[0120] Step 7: Place the structure obtained in Step 6 in a mask template for the electron transport layer, and place the mask template in a vacuum deposition device. Evacuate to 4.5×10 -4 Pa, and then evaporate LiF, C60, and BCP. The deposition rates are respectively The thicknesses are 0.8 nm, 8 nm, and 1.3 nm respectively;

[0121] Step 8: Place the structure obtained in Step 7 in a mask template for silver evaporation, and then place the mask template in a vacuum deposition device. Evacuate to 7×10 -4 Pa and perform silver electrode evaporation at a rate of The thickness is 150 nm, and the preparation of the perovskite single-junction cell is completed.

[0122] Example 3

[0123] The preparation method of the perovskite tandem cell in this example includes the following steps:

[0124] Step 1: Cut a 15×15 cm 2 silicon bottom cell into 2×2 cm 2 small cells, with a 1.2×1.2 cm 2 composite layer at the exact center of the small cells. Control the cutting precision error within 1 mm. Anneal the cut bottom cells at 200 °C for 15 min and treat them in ozone for 30 min to obtain a conductive silicon substrate. Among them, the thickness of the small cells is 3 μm and the thickness of the composite layer is 10 nm;

[0125] Step 2: Transfer the substrate to a spin coater in a nitrogen glove box. Spin coat a layer of 4PADCB solution on the substrate surface. The dosage of the 4PADCB solution is 70 uL, the concentration is 0.5 mg / mL, the spin coating speed is 3000 rpm, the acceleration is 3000 rpm / s, and it lasts for 30 s. After annealing the substrate spin coated with the 4PADCB solution on a hot plate at 100 °C for 10 min, a 4PADCB layer is obtained;

[0126] Step 3: Spin coat a layer of 2PACz solution on the surface of the 4PADCB layer. Part of the 2PACz solution fills the voids of the 4PADCB layer. The dosage of the 2PACz solution is 70 uL, the concentration is 1.5 mg / mL, the spin coating speed is 3000 rpm, the acceleration is 3000 rpm / s, and it lasts for 30 s. After annealing the substrate spin coated with the 2PACz solution on a hot plate at 100 °C for 10 min, a 2PACz layer is obtained. After completing the preparation of the hole transport layer, clean the hole transport layer with isopropanol;

[0127] Step 4: Place the structure obtained in Step 3 in a mask of the perovskite light-absorbing layer, and place the mask in a vacuum evaporation device. Evacuate to 4.5×10 -4 Pa, adjust the rate of cesium bromide to the rate of lead iodide to evaporate cesium bromide and lead iodide to form an inorganic framework with a thickness of 300 nm;

[0128] Step 5: Weigh 51.59 mg of FAI, 18.75 mg of FABr, 5.7 mg of MACl, and 12.6 mg of MABr and dissolve them in 1 mL of propanol. Stir at 25 °C for 0.5 h to obtain a perovskite precursor solution;

[0129] Step 6: Spin-coat 105 μL of the precursor solution onto the surface of the inorganic framework at a spin speed of 4000 rpm, a spin acceleration of 4000 rpm / s, and a spin time of 30 s. Then, transfer the substrate to a heating stage and perform heat annealing at an ambient humidity of 62% and a temperature of 170 °C for 30 min to obtain a perovskite light-absorbing layer with a thickness of 500 nm.

[0130] Step 7: In the mask template of the structure electron transport layer prepared in Step 6, place the mask template in a vacuum deposition device and evacuate to 5×10 -4 Pa, and then deposit LiF and C60. The deposition rates are with thicknesses of 1 nm and 10 nm respectively.

[0131] Step 8: Place the stacked structure prepared in Step 7 in the chamber of an atomic layer deposition system to deposit a buffer layer on the surface of the electron transport layer. Among them, the vacuum degree is 20 Pa, the deposition temperature is 150 °C, the pressure of the water source is 50 Pa, the pressure of the tin source is 25 Pa, and the number of cycles is 100 times.

[0132] Step 9: Place the stacked structure prepared in Step 8 in a 1.1×1.1 cm 2 mask template of the front composite layer, and perform DC magnetron sputtering of the front composite layer on the surface of the buffer layer. The substrate temperature during sputtering is 60 °C, the pressure in the sputtering chamber is 9.0×10 - 4 Pa, the argon flow rate is 8 sccm, the oxygen flow rate is 8 sccm, the sputtering intensity is 200 W, and the sputtering time is 2.5 min.

[0133] Step 10: Place the stacked structure obtained in the previous step in the mask templates of the positive electrode and the back electrode respectively, and then place the mask template in a vacuum deposition device to deposit a silver electrode and prepare the positive electrode and / or the back electrode. Among them, the vacuum degree is 7×10 -4 Pa, and the deposition rate is the thickness of the positive electrode is 400 nm, and the thickness of the back electrode is 200 nm.

[0134] Step 11: Place the stacked structure prepared in Step 10 on a 1.1×1.1 cm 2 mask template, and then place the mask template in a vacuum deposition device to prepare an antireflection layer. The vacuum degree is 10×10 -4 Pa, and the thickness is 100 nm.

[0135] Example 4

[0136] The preparation method of the perovskite stacked cell in this example includes the following steps:

[0137] Step 1: Cut a silicon bottom cell with a size of 15×15 cm 2 into small cells with a size of 2×2 cm 2 . Each small cell has a composite layer with a size of 1.2×1.2 cm 2 at its center. Control the cutting precision error within 1 mm. Anneal the cut bottom cells at 180 °C for 18 min and treat them in ozone for 25 min to obtain a conductive silicon substrate. The thickness of the small cell is 2.5 μm, and the thickness of the composite layer is 9 nm;

[0138] Step 2: Transfer the substrate to a spin coater in a nitrogen glove box. Spin coat a layer of Me-4PACz solution on the substrate surface. The dosage of the Me-4PACz solution is 65 μL, the concentration is 1.1 mg / mL, the spin coating speed is 3200 rpm, the acceleration is 3200 rpm / s, and it lasts for 25 s. After annealing the substrate with the spin-coated Me-4PACz solution on a hot plate at 98 °C for 11 min, obtain a Me-4PACz layer;

[0139] Step 3: Spin coat a layer of MeO-2PACz solution on the surface of the Me-4PACz layer. Part of the MeO-2PACz solution fills the voids in the Me-4PACz layer. The dosage of the MeO-2PACz solution is 75 μL, the concentration is 3.0 mg / mL, the spin coating speed is 3200 rpm, the acceleration is 3200 rpm / s, and it lasts for 25 s. After annealing the substrate with the spin-coated MeO-2PACz solution on a hot plate at 98 °C for 11 min, obtain a MeO-2PACz layer, completing the preparation of the hole transport layer;

[0140] Step 4: Place the structure obtained in Step 3 in a mask of a perovskite light-absorbing layer. Place the mask in a vacuum evaporation device. Evacuate to 5.5×10 -4 Pa, adjust the rate of cesium bromide to and the rate of lead iodide to Evaporate cesium bromide and lead iodide to form an inorganic framework with a thickness of 280 nm;

[0141] Step 5: Weigh 52.11 mg of BAI, 18.54 mg of FABr, 5.2 mg of BACl, and 13.3 mg of MABr and dissolve them in 1 mL of DMF. Stir with shaking at 30 °C for 0.5 h to obtain a perovskite precursor solution;

[0142] Step 6: Spin-coat 95 uL of the precursor solution onto the surface of the inorganic framework at a spin speed of 3500 rpm, a spin acceleration of 3500 rpm / s, and a spin time of 28 s. Then, transfer the substrate to a heating stage and perform heat annealing at an ambient humidity of 58% and a temperature of 155°C for 25 min to obtain a perovskite light absorption layer with a thickness of 450 nm;

[0143] Step 7: In the mask of the structure electron transport layer prepared in Step 6, place the mask in a vacuum deposition equipment and evacuate to 5.5×10 -4 Pa, and then deposit LiF and C60. The deposition rates are with thicknesses of 1.2 nm and 12 nm respectively;

[0144] Step 8: Place the stacked structure prepared in Step 7 in the chamber of atomic layer deposition to deposit a buffer layer on the surface of the electron transport layer. Among them, the vacuum degree is 25 Pa, the deposition temperature is 155°C, the pressure of the water source is 45 Pa, the pressure of the tin source is 20 Pa, and the number of cycles is 85 times;

[0145] Step 9: Place the stacked structure prepared in Step 8 in a 1.1×1.1 cm 2 mask of the front composite layer, and magnetron sputter the front composite layer on the surface of the buffer layer by DC. The substrate temperature during sputtering is 63°C, the pressure in the sputtering chamber is 9.2×10 - 4 Pa, the argon flow rate is 7 sccm, the oxygen flow rate is 7 sccm, the sputtering intensity is 185 W, and the sputtering time is 4 min;

[0146] Step 10: Place the stacked structure obtained in the previous step in the masks of the positive electrode and the back electrode respectively, and then place the mask in a vacuum deposition equipment to deposit a silver electrode and prepare the positive electrode and / or the back electrode. Among them, the vacuum degree is 6×10 -4 Pa, and the deposition rate is the thickness of the positive electrode is 350 nm, and the thickness of the back electrode is 150 nm;

[0147] Step 11: Place the stacked structure prepared in Step 10 on a 1.1×1.1 cm 2 mask, and then place the mask in a vacuum deposition equipment to prepare an antireflection layer. The vacuum degree is 10.3×10 -4 Pa, and the thickness is 105 nm.

[0148] Comparative Example 1

[0149] This comparative example is basically the same as Example 1 in terms of raw materials, steps, and process conditions, except that:

[0150] During the preparation of the hole transport layer, there is only a single layer of 4PADCB layer.

[0151] Comparative Example 2

[0152] This comparative example is basically the same as Example 3 in terms of the raw materials, steps, and process conditions used, with the only difference being:

[0153] During the preparation of the hole transport layer, there is only a single layer of 4PADCB layer.

[0154] Comparative Example 3

[0155] This comparative example is basically the same as Example 3 in terms of the raw materials, steps, and process conditions used, with the only difference being:

[0156] Step 3: Spin-coat a layer of 4PADCB solution on the surface of the first layer of 4PADCB layer. The amount of the 4PADCB solution is 70 μL, the concentration is 1.5 mg / mL, the spin-coating speed is 3000 rpm, the acceleration is 3000 rpm / s, and it lasts for 30 s. After placing the substrate spin-coated with the 4PADCB solution on a hot stage and annealing it at 100 °C for 10 min, the second layer of 4PADCB layer is obtained. After completing the preparation of the hole transport layer, the hole transport layer is cleaned with absolute ethanol.

[0157] The perovskite solar cells prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to electrical performance tests. The specific results are shown in Table 1. Among them, the short-circuit current density (Jsc), open-circuit voltage (Voc), conversion efficiency (PCE), and fill factor (FF) were all measured under standard test conditions (AM1.5, 25 °C, 1000 W / m 2 ).

[0158] Table 1 Electrical performance test results of the cells prepared in Examples 1 to 4 and Comparative Examples 1 to 3

[0159]

[0160] As can be seen from Table 1, the electrical performance parameters of Examples 1 to 2 are significantly better than those of Comparative Example 1, and the electrical performance parameters of Examples 3 to 4 are significantly better than those of Comparative Examples 2 to 3. Specifically as follows:

[0161] For the perovskite single-junction cell, the open-circuit voltage is 1.17 - 1.18 V, the short-circuit current is 21.2 - 21.5 mA / cm 2 , the fill factor is 75 - 78%, and the conversion efficiency is 18 - 20%.

[0162] For the perovskite tandem cell, the open-circuit voltage is 1.84 - 1.85 V, the short-circuit current is 20.10 - 20.21 mA / cm 2, the fill factor is 77.5 - 78.5%, and the conversion efficiency is 28.5 - 29.5%.

[0163] It should be noted that through comparison, it can be seen that the various electrical performance parameters of Comparative Example 2 and Comparative Example 3 are not very different. This is because the void size of the first layer of 4PADCB layer is smaller than the molecular size of the self-assembled monolayer matrix layer material and larger than the molecular size of the self-assembled monolayer filling layer material. Even if 4PADCB solution is spin-coated on the surface of the first layer of 4PADCB layer, 4PADCB molecules cannot enter the voids to form an anchor with the substrate and will almost all be removed during the subsequent cleaning process. Therefore, the various electrical performance parameters are not very different from those of Comparative Example 2 with only a single layer of 4PADCB layer spin-coated.

[0164] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A hole transport layer, characterized in that: It comprises a self-assembled monomolecular matrix layer and a self-assembled monomolecular filling layer filled in the gaps of the self-assembled monomolecular matrix layer. The molecular size of the self-assembled monomolecular filling layer material is smaller than that of the self-assembled monomolecular matrix layer material.

2. The hole transport layer according to claim 1, characterized in that The self-assembled monomolecular matrix layer material is a mixture of one or more of (4-(7H-dibenzo[c,g]carbazole-7-yl)butyl)phosphonic acid, (4-(9H-carbazole-9-yl)butyl)phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, and 4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazole-7-yl)butylphosphonic acid in any proportion; And / or, the self-assembled monomolecular filling layer material is a mixture of one or more of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, (2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl)phosphonic acid, and 2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in any proportion.

3. The hole transport layer according to claim 1, characterized in that The hole transport layer is a single-layer structure.

4. The hole transport layer according to any one of claims 1 to 3, characterized in that: In the hole transport layer, the mass ratio of the self-assembled monomolecular matrix layer material to the self-assembled monomolecular filling layer material is 1:2 to 1:4.

8.

5. A method for preparing a hole transport layer, characterized in that: For preparing the hole transport layer according to any one of claims 1 to 4, the preparation method comprises the following steps: Step a: forming a layer of a solution of a self-assembled monomolecular matrix layer material on the surface of the substrate; Step b: annealing the substrate having the solution of the self-assembled monomolecular matrix layer material formed thereon to obtain a self-assembled monomolecular matrix layer, wherein the self-assembled monomolecular matrix layer has gaps; Step c: forming a layer of solution of self-assembled monomolecular filling layer material on the surface of the self-assembled monomolecular matrix layer, and partially filling the solution of the self-assembled monomolecular filling layer material into the gaps; Step d: performing secondary annealing on the substrate having the solution of the self-assembled monomolecular filling layer material formed thereon to obtain a self-assembled monomolecular filling layer.

6. The method for preparing a hole transport layer according to claim 5, characterized in that: The solution concentration of the self-assembled monomolecular filling layer material is greater than the solution concentration of the self-assembled monomolecular matrix layer material.

7. The method for preparing a hole transport layer according to claim 6, characterized in that: In the step a, the solution concentration of the self-assembled monomolecular matrix layer material is 0.3-1.1 mg / mL; And / or, in step c, the solution concentration of the self-assembled monomolecular filling layer material is 1.15-3 mg / mL.

8. The method for preparing a hole transport layer according to claim 7, characterized in that: The volume ratio of the solution of the self-assembled monomolecular matrix layer material to the solution of the self-assembled monomolecular filling layer material is 55-70:68-75.

9. The method for preparing a hole transport layer according to any one of claims 5 to 8, characterized in that: The step d further includes the following steps: Step e: Clean the surface of the hole transport layer to remove the self-assembled monomolecular filling layer material that is not anchored to the substrate.

10. A perovskite solar cell, characterized in that: The method comprises the hole transport layer according to any one of claims 1 to 4.

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