Organic electron transport layer, perovskite solar cell and preparation method and application thereof

Abstract

The present invention provides a novel organic electron transport layer, a perovskite solar cell and a preparation method and application thereof, wherein the battery structure comprises an anode (ITO glass), a hole transport layer, a perovskite layer, an organic electron transport layer and a cathode. The preparation method of the organic electron transport layer is to dissolve m-ITTC molecules with long chains in a chlorobenzene solution of PCBM, and directly spin-coat them on the perovskite layer to form a high-quality organic electron transport layer film for electron transmission, with a photoelectric conversion efficiency of 8.37193%. The doping of m-ITIC can alleviate the aggregation of PCBM, so that the formed organic electron transport layer film is more evenly covered on the perovskite layer, which is conducive to the transmission of electrons and can block holes at the same time, greatly improving the efficiency and photoelectric performance of the battery; and the operation is simple, the cost is low, and commercial production can be carried out.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a novel organic electron transport layer, a perovskite solar cell, and a preparation method and application thereof. Background Art

[0002] Compared with the booming hole transport layer, the electron transport layer of inverted perovskite solar cells has been little studied. 61 -Butyric acid methyl ester (PCBM) is the most common electron transport material. It has high electron mobility and low-temperature solution processing performance. However, due to the low viscosity and solubility of PCBM in organic solvents, it is difficult to form a dense film on the perovskite film. Therefore, the perovskite film cannot be completely covered by PCBM, causing it to directly contact the Ag or Al electrode, resulting in charge recombination and accelerating the degradation of the interface layer.

[0003] At present, no electron transport layer material that can completely replace PCBM has been found. The film-forming properties of PCBM are improved only by adding additives. For example, Li JiaXun et al. added long-chain molecules EVA to PCBM. However, the solubility of EVA in chlorobenzene is not high, so it is difficult to accurately dope EVA molecules in PCBM. Although some small organic molecules can be doped into PCBM as dopants to improve the performance of the device, the cost is relatively high. Therefore, it is particularly important to find a dopant that can improve the performance and stability of the device and is low-cost and easy to obtain, which is particularly important for the preparation of high-performance and low-cost planar perovskite solar cells.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a novel organic electron transport layer, a perovskite solar cell and a preparation method and application thereof, so as to improve the performance of the electron transport layer and enhance the energy conversion efficiency of the battery.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A novel method for preparing an organic electron transport layer, the preparation method comprising the following steps:

[0008] Step 1, mixing m-ITTC into PCBM according to a proportion to form a mixed solution, placing the mixed solution in chlorobenzene for mixing, stirring and filtering to form a PCBM:m-ITTC precursor solution;

[0009] Step 2: spin-coat the PCBM:m-ITTC precursor solution on a coating machine for 20-40 seconds, and form an organic electron transport layer after curing.

[0010] In the method for preparing the novel organic electron transport layer as described above, preferably, the doping concentration of m-ITTC in PCBM in the mixed solution is 0.5-2wt%;

[0011] Preferably, in step 1, the stirring time is 12 hours.

[0012] In the method for preparing the novel organic electron transport layer as described above, preferably, the concentration of the PCBM:m-ITTC precursor solution is 18-22 mg / ml;

[0013] Preferably, the rotation speed of the spin coating on the coating machine is 1500-2500 rpm.

[0014] An organic electron transport layer prepared by the novel method for preparing an organic electron transport layer as described above.

[0015] An application of an organic electron transport layer, and the application of the organic electron transport layer in the preparation of a photovoltaic device.

[0016] A method for preparing a perovskite solar cell, the method comprising the following steps:

[0017] Step S1, cleaning a glass substrate coated with an anode material and treating it with ultraviolet light to obtain a pre-treated substrate substrate;

[0018] Step S2, depositing PEDOT:PSS on the pretreated substrate, annealing at 130-150° C. for 15-20 min, and then naturally cooling to room temperature to obtain a hole transport layer;

[0019] Step S3, moving the substrate with the hole transport layer into a glove box, spin-coating a perovskite precursor solution on the hole transport layer using a one-step anti-solvent method, and annealing at 90-100° C. for 10-15 min to obtain a perovskite layer, i.e., an active layer;

[0020] Step S4, preparing an organic electron transport layer on the perovskite layer;

[0021] Step S5, depositing a cathode material onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell;

[0022] The organic electron transport layer is prepared by using the preparation method of the novel organic electron transport layer as described above.

[0023] In the method for preparing a perovskite solar cell as described above, preferably, in step S3, the perovskite precursor solution is prepared by the following method:

[0024] Dissolving donor A and donor B in an organic solvent and stirring to obtain a perovskite precursor solution;

[0025] Wherein, the donor A is methyl ammonium iodide, and the donor B is lead iodide;

[0026] Preferably, the organic solvent is N,N-dimethylformamide.

[0027] In the method for preparing a perovskite solar cell as described above, preferably, the molar ratio of the donor A to the donor B is 1:(1-5).

[0028] In the method for preparing a perovskite solar cell as described above, preferably, the total mass percentage of the donor A and the donor B in the organic solution is 35-50wt%.

[0029] A perovskite solar cell prepared by the method for preparing a perovskite solar cell as described above.

[0030] Beneficial effects:

[0031] The present invention adopts a novel dopant m-ITTC doped in a traditional electron transport layer to prepare a highly efficient planar perovskite solar cell, which mainly has the following excellent effects:

[0032] 1. Improved the performance of perovskite solar cells. The present invention adopts a new dopant m-ITTC doped in the traditional electron transport layer as the electron transport layer of the perovskite solar cell, which can not only form a uniform and dense electron transport layer, prevent water and oxygen from corroding the perovskite layer, but also passivate the surface defects of the perovskite, and also has the characteristics of a LUMO energy level that is more matched with the perovskite. The electron transport layer can not only transmit electrons well but also effectively block holes from the perovskite layer, reducing the electron recombination loss at the interface, thereby improving the open circuit voltage, short circuit current density, and fill factor of the perovskite solar cell, and finally achieving the improvement of the performance of the perovskite solar cell. The energy conversion efficiency of the planar heterojunction perovskite solar cell prepared by the preparation method of the present invention reaches 8.37%.

[0033] 2. The preparation method of the novel organic electron transport layer is simple. The present invention utilizes the novel dopant m-ITTC to dope the traditional electron transport layer, and the obtained precursor solution is directly spin-coated on the perovskite layer without the need for annealing. The operation is simple, and the performance and stability of the device are improved while the cost is low and the availability is easy, and the preparation of large-area thin films can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0035] Figure 1 A schematic diagram of the structure of a perovskite solar cell according to an embodiment of the present invention;

[0036] Figure 2 is the molecular structure formula of the dopant m-ITTC of the present invention;

[0037] Figure 3 The ultraviolet absorption spectra of the organic electron transport layers prepared in Examples 1-4 and Comparative Example 1 of the present invention;

[0038] Figure 4 The current density-voltage characteristic curves of the perovskite solar cells prepared in Examples 1-4 of the present invention and Comparative Example 1;

[0039] Figure 5 are the contact angles of the PCBM:m-ITTC films prepared in Examples 1-4 of the present invention and Comparative Example 1 (wherein a is the contact angle in Comparative Example 1, b is the contact angle in Example 2, c is the contact angle in Example 1, d is the contact angle in Example 3, and e is the contact angle in Example 4). DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0041] The present invention will be described in detail below in conjunction with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0042] The perovskite solar cell doped with an organic electron transport layer provided by the present invention aims at the shortcomings of the electron transport layer material [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) commonly used in the current planar perovskite solar cells, and provides a planar perovskite solar cell with an organic electron transport layer doped with a novel dopant m-ITTC, thereby improving the performance of the cell, being simple to operate, and being able to achieve large-area preparation.

[0043] like Figure 1 As shown, the structure of the perovskite solar cell device of the present invention includes from bottom to top: substrate (glass), anode (ITO), hole transport layer (HTL), perovskite layer (CH3NH3PbI3), electron transport layer (ETL), cathode (Ag or Al); wherein m-ITTC is uniformly doped in PCBM. Figure 2The figure shows the molecular structure of the dopant m-ITTC used in the organic electron transport layer of the present invention, wherein m-ITTC is also called indentrienedithia(3,2-b)thiophene, which is used in photovoltaic devices to improve the performance of the devices.

[0044] The organic electron transport layer of the present invention adopts dopant m-ITTC and traditional electron transport material PCBM dissolved in organic solvent to form electron transport layer precursor liquid PCBM:m-ITTC, and spin-coated the electron transport layer precursor liquid on a sizing machine to solidify to form an electron transport layer, and the spin coating speed is 2500rpm, which is used to transmit electrons to block holes, and can block water and oxygen corrosion, while reducing the close contact between the cathode and the active layer, thereby reducing the carrier recombination loss at the interface, thereby improving the performance of the device. In addition, when preparing the organic electron transport layer, high temperature annealing treatment is not required, the operation is simple, and large-area preparation can be achieved.

[0045] The organic electron transport layer in the present invention can also be used in other photovoltaic devices, such as organic solar cells.

[0046] The present invention provides a method for preparing a perovskite solar cell, the preparation method comprising the following steps:

[0047] Step S1, washing and drying the glass substrate coated with the anode material and then treating it with ultraviolet light to obtain a pre-treated substrate substrate. The ultraviolet light treatment can further clean the substrate substrate and adjust the energy level of the ITO glass at the same time.

[0048] In a specific embodiment of the present invention, the anode material is indium tin oxide (ITO) for collecting holes.

[0049] Step S2, depositing PEDOT:PSS on the pretreated substrate, annealing at 130-150°C (such as 135°C, 140°C, 145°C, 150°C) for 15-20min (such as 16min, 18min, 19min), and then naturally cooling to room temperature to obtain a hole transport layer; preferably, spin coating the PEDOT:PSS solution on the pretreated substrate using a coating machine at a spin coating rate of 3000-4000rpm.

[0050] Step S3, move the substrate with the hole transport layer into the glove box, spin-coat the perovskite precursor solution (CH3NH3PbI3) on the hole transport layer using a one-step anti-solvent method, quickly drip chlorobenzene during the spin coating process and continue spin coating, keep warm at 90-100°C (such as 92°C, 94°C, 96°C, 98°C) for 10-15min (such as 11min, 12min, 13min, 14min) for annealing to obtain a perovskite layer, i.e., an active layer.

[0051] In a specific embodiment of the present invention, the perovskite precursor solution is prepared by the following method:

[0052] Dissolving donor A and donor B in an organic solvent and stirring to obtain a perovskite precursor solution;

[0053] Among them, donor A is methyl ammonium iodide (CH3NH3I), and donor B is lead iodide (PbI2); preferably, the organic solvent is N,N-dimethylformamide (DMF).

[0054] In a specific embodiment of the present invention, the molar ratio of donor A to donor B is 1:(1-5) (e.g., 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5). The total mass percentage of donor A and donor B in the organic solution is 35-50wt% (e.g., 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%).

[0055] Step S4: preparing an organic electron transport layer on the perovskite layer.

[0056] In a specific embodiment of the present invention, the method for preparing an organic electron transport layer comprises the following steps:

[0057] Step S41, m-ITTC is mixed into PCBM according to a proportion to form a mixed solution, the mixed solution is placed in chlorobenzene for mixing, stirred for 12 hours, and filtered with a filter head before use to form a PCBM:m-ITTC precursor solution after filtration.

[0058] In a specific embodiment of the present invention, the doping concentration of m-ITTC in PCBM in the mixed solution is 0.5-2wt% (e.g., 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%); preferably, the doping concentration of m-ITTC in PCBM is 1wt%. The concentration of PCBM:m-ITTC precursor solution is 18-22mg / ml (e.g., 18.5mg / ml, 19mg / ml, 19.5mg / ml, 20mg / ml, 20.5mg / ml, 21mg / ml).

[0059] Step S42, spin-coat the PCBM:m-ITTC precursor solution on a sizing machine for 20-40s (e.g., 25s, 30s, 35s, 40s, 45s), and form an organic electron transport layer after curing. Preferably, the rotation speed of the spin coating on the sizing machine is 1500-2500rpm (e.g., 1600rpm, 1800rpm, 2000rpm, 2200rpm, 2400rpm). In the steps of the present invention, the rotation speed is reduced when the PCBM:m-ITTC precursor solution is spin-coated. The purpose of reducing the rotation speed is to increase the thickness of the organic electron transport layer, the first purpose of which is to completely cover the perovskite layer, and the second is to match the electrons and holes.

[0060] Step S5: depositing the cathode material onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell.

[0061] In a specific embodiment of the present invention, the cathode material is metal aluminum (Al) or silver (Ag).

[0062] The present invention also provides a perovskite solar cell prepared by the method for preparing a perovskite solar cell;

[0063] And an organic electron transport layer prepared by the method for preparing an organic electron transport layer.

[0064] The preparation method of the organic electron transport layer of the present invention dissolves the m-ITTC molecules with long chains in a chlorobenzene solution of PCBM, and directly spin-coats them on the perovskite layer to form a high-quality organic electron transport layer film for electron transport, with a photoelectric conversion efficiency of 8.37193%. The doping of m-ITIC can alleviate the aggregation of PCBM, so that the formed organic electron transport layer film is more evenly covered on the perovskite layer, which is conducive to the transmission of electrons and can block holes at the same time, greatly improving the efficiency and photoelectric performance of the battery. It is simple to operate, low in cost, and can be commercially produced.

[0065] The materials and reagents used in the present embodiment and the comparative example are all commercially available products.

[0066] Example 1

[0067] The present embodiment provides a method for preparing a perovskite solar cell doped with an organic electron transport layer, comprising the following steps:

[0068] Step S1, the anode glass substrate plated with indium tin oxide ITO is ultrasonically cleaned 3 times with detergent, distilled water, acetone, and ethanol for 15 minutes each time, and then dried with nitrogen. The dried ITO glass substrate is placed in an ultraviolet cleaning surface treatment device for 15 minutes to obtain a pretreated substrate substrate.

[0069] Step S2, spin-coating PEDOT:PSS on the pretreated glass substrate, annealing at 140°C for 15 minutes, and then naturally cooling to room temperature to form a hole transport layer.

[0070] Step S3, CH3NH3I and PbI2 are dissolved in N,N-dimethylformamide (DMF) solution at a molar ratio of 1:2, the total mass fraction of PbI2 and CH3NH3I in the solution is 40wt%, and stirred at room temperature to obtain a perovskite precursor solution (CH3NH3PbI3). The perovskite precursor solution is spin-coated on the hole transport layer at a speed of 5000r / min, and then the anti-solvent chlorobenzene is quickly added dropwise at the 5th second of rotation to promote the rapid crystallization of the perovskite layer. After annealing at 100°C for 10 minutes, a black perovskite layer with a thickness of 300nm is obtained, which is also the active layer.

[0071] Step S4, spin coating the electron transport layer precursor solution on the active layer to form an organic electron transport layer, the rotation speed of the electron transport layer during spin coating is 2500 rpm, and the specific steps include:

[0072] Step s41, m-ITTC is mixed into PCBM in a certain proportion, the doping concentration is 1.0wt%, placed in chlorobenzene, stirred for 12 hours, and filtered with a 0.45 micron filter before use to form a PCBM:m-ITTC precursor solution; the concentration of the PCBM:m-ITTC precursor solution is 20mg / ml.

[0073] Step s42, spin-coating the PCBM:m-ITTC precursor solution on a coating machine for 30 seconds, and forming an organic electron transport layer after curing; that is, a PCBM:m-ITTC film.

[0074] Step S5: The cathode material Al is deposited onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell.

[0075] The device structure obtained in the embodiment of the present invention is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM:m-ITTC / Al. The performance of the device is tested. Under the optimal conditions, the device has a power consumption of 100 mW cm -2 The open circuit voltage under simulated sunlight is 0.83 V and the short circuit current is 15.54 mA cm -2 , the filling factor is 64.64% and the photoelectric conversion efficiency is 8.37%.

[0076] Example 2

[0077] The preparation of the perovskite solar cell doped with an organic electron transport layer in this embodiment includes the following steps:

[0078] Step S1, the anode glass substrate plated with indium tin oxide ITO is ultrasonically cleaned 3 times with detergent, distilled water, acetone, and ethanol for 15 minutes each time, and then dried with nitrogen. The dried ITO glass substrate is placed in an ultraviolet cleaning surface treatment device for 15 minutes to obtain a pretreated substrate substrate.

[0079] Step S2, spin-coating PEDOT:PSS on the pretreated glass substrate, annealing at 130°C for 20 minutes, and then naturally cooling to room temperature to form a hole transport layer.

[0080] Step S3, CH3NH3I and PbI2 are dissolved in N,N-dimethylformamide (DMF) solution at a molar ratio of 1:2, the total mass fraction of PbI2 and CH3NH3I in the solution is 40wt%, and stirred at room temperature to obtain a perovskite precursor solution (CH3NH3PbI3). The perovskite precursor solution is spin-coated on the hole transport layer at a speed of 5000r / min, and then the anti-solvent chlorobenzene solution is quickly added dropwise when rotating to the 5th second to promote the rapid crystallization of the perovskite layer. After annealing at 95°C for 13 minutes, a black perovskite layer with a thickness of 300nm is obtained, which is also the active layer.

[0081] Step S4, spin coating the electron transport layer precursor solution on the active layer to form an organic electron transport layer, the rotation speed of the electron transport layer during spin coating is 1500 rpm, and the specific steps include:

[0082] Step s41, m-ITTC is mixed into PCBM in a certain proportion, the doping concentration is 0.5wt%, placed in chlorobenzene, stirred for 12h, and filtered with a 0.45 micron filter before use to form a PCBM:m-ITTC precursor solution; the concentration of the PCBM:m-ITTC precursor solution is 18mg / ml.

[0083] Step s42, spin-coating the PCBM:m-ITTC precursor solution on a coating machine for 30 seconds, and forming an organic electron transport layer after curing; that is, a PCBM:m-ITTC film.

[0084] Step S5: The cathode material Al is deposited onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell.

[0085] The device structure obtained in the embodiment of the present invention is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM:m-ITTC / Al. The performance of the device is tested. Under the optimal conditions, the device has a power consumption of 100 mW cm -2 The open circuit voltage under simulated sunlight is 0.83 V and the short circuit current is 15.22 mA cm -2 , the filling factor is 59.18%, and the photoelectric conversion efficiency is 7.438%.

[0086] Example 3

[0087] The preparation of the doped organic electron transport layer perovskite solar cell in this embodiment includes the following steps: Step S1, the anode glass substrate plated with indium tin oxide ITO is ultrasonically washed three times with detergent, distilled water, acetone, and ethanol, each time for 15 minutes, and then dried with nitrogen. The dried ITO glass substrate is placed in an ultraviolet cleaning surface treatment device for 15 minutes to obtain a pre-treated substrate substrate.

[0088] Step S2, spin-coating PEDOT:PSS on the pretreated glass substrate, annealing at 150° C. for 15 min, and then naturally cooling to room temperature to form a hole transport layer.

[0089] Step S3, CH3NH3I and PbI2 are dissolved in N,N-dimethylformamide (DMF) solution at a molar ratio of 1:2, the total mass fraction of PbI2 and CH3NH3I in the solution is 40wt%, and stirred at room temperature to obtain a perovskite precursor solution (CH3NH3PbI3). The perovskite precursor solution is spin-coated on the hole transport layer at a speed of 5000r / min, and then the anti-solvent chlorobenzene is quickly added dropwise at the 5th second of rotation to promote the rapid crystallization of the perovskite layer. After annealing at 100°C for 15 minutes, a black perovskite layer with a thickness of 300nm is obtained, which is the active layer.

[0090] Step S4, spin coating the electron transport layer precursor solution on the active layer to form an organic electron transport layer, the rotation speed of the electron transport layer during spin coating is 2500 rpm, and the specific steps include:

[0091] Step s41, m-ITTC is mixed into PCBM in a certain proportion, the doping concentration is 1.5wt%, placed in chlorobenzene, stirred for 12h, and filtered with a 0.45 micron filter before use to form a PCBM:m-ITTC precursor solution; the concentration of the PCBM:m-ITTC precursor solution is 22mg / ml.

[0092] Step s42, spin-coating the PCBM:m-ITTC precursor solution on a coating machine for 30 seconds, and forming an organic electron transport layer after curing; that is, a PCBM:m-ITTC film.

[0093] Step S5: The cathode material Al is deposited onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell.

[0094] The device structure obtained in the embodiment of the present invention is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM:m-ITTC / Al. The performance of the device is tested. Under the optimal conditions, the device has a power consumption of 100 mW cm-2 The open circuit voltage under simulated sunlight is 0.84 V and the short circuit current is 15.23 mA cm -2 , the filling factor is 55.22%, and the photoelectric conversion efficiency is 7.05%.

[0095] Example 4

[0096] The preparation of the perovskite solar cell doped with an organic electron transport layer in this embodiment includes the following steps:

[0097] Step S1, the anode glass substrate plated with indium tin oxide ITO is ultrasonically cleaned 3 times with detergent, distilled water, acetone, and ethanol for 15 minutes each time, and then dried with nitrogen. The dried ITO glass substrate is placed in an ultraviolet cleaning surface treatment device for 15 minutes to obtain a pretreated substrate substrate.

[0098] Step S2, spin-coating PEDOT:PSS on the pretreated glass substrate, annealing at 140°C for 15 minutes, and then naturally cooling to room temperature to form a hole transport layer.

[0099] Step S3, CH3NH3I and PbI2 are dissolved in N,N-dimethylformamide (DMF) solution at a molar ratio of 1:2, the total mass fraction of PbI2 and CH3NH3I in the solution is 40wt%, and stirred at room temperature to obtain a perovskite precursor solution (CH3NH3PbI3). The perovskite precursor solution is spin-coated on the hole transport layer at a speed of 5000r / min, and then the anti-solvent chlorobenzene solvent is quickly added dropwise at the 5th second of rotation to promote the rapid crystallization of the perovskite layer. After annealing at 90°C for 15 minutes, a black perovskite layer with a thickness of 300nm is obtained, which is the active layer.

[0100] Step S4, spin coating the electron transport layer precursor solution on the active layer to form an organic electron transport layer, the rotation speed of the electron transport layer during spin coating is 2500 rpm, and the specific steps include:

[0101] Step s41, m-ITTC is mixed into PCBM in a certain proportion, the doping concentration is 2.0wt%, placed in chlorobenzene, stirred for 12h, and filtered with a 0.45 micron filter before use to form a PCBM:m-ITTC precursor solution; the concentration of the PCBM:m-ITTC precursor solution is 20mg / ml.

[0102] Step s42, spin-coating the PCBM:m-ITTC precursor solution on a coating machine for 30 seconds, and forming an organic electron transport layer after curing; that is, a PCBM:m-ITTC film.

[0103] Step S5: The cathode material Al is deposited onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell.

[0104] The device structure obtained in the embodiment of the present invention is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM:m-ITTC / Al. The performance of the device is tested. Under the optimal conditions, the device has a power consumption of 100 mW cm -2 The open circuit voltage under simulated sunlight is 0.84 V and the short circuit current is 13.564 mA cm -2 , the filling factor is 64.26%, and the photoelectric conversion efficiency is 7.31%.

[0105] like Figure 3 Shown are the ultraviolet absorption spectra of the organic electron transport layers prepared in Examples 1-4 of the present invention and Comparative Example 1. It can be seen from the figure that neither the organic electron transport layers of Examples 1-4 nor the organic electron transport layers in Comparative Example 1 affect the light absorption of the perovskite layer, and when the m-ITTC doping concentration is 1wt%, the spectral intensity is slightly higher than that of the samples prepared in the other embodiments, so the best photovoltaic parameters and performance can be obtained when the m-ITTC doping concentration is 1wt%.

[0106] Figure 4 Current density-voltage characteristic curves of the perovskite solar cells prepared in Examples 1-4 of the present invention and Comparative Example 1.

[0107] Figure 5 It is the contact angle of the PCBM:m-ITTC film prepared in Examples 1-4 of the present invention and Comparative Example 1. As can be seen from the figure, the contact angles of the organic electron transport layer films doped with m-ITTC are greater than the contact angle of the pure PCBM film. It can be known that the doping of m-ITTC can improve the hydrophobicity of the organic electron transport layer, and when the m-ITTC doping concentration is 1wt%, the contact angle is the largest, indicating that the hydrophobicity is the best, which can well prevent external moisture from corroding the perovskite layer, thereby improving the photoelectric conversion efficiency of the device.

[0108] Example 5

[0109] The difference between this embodiment and embodiment 1 is that in step S3, CH3NH3I and PbI2 are dissolved in N,N-dimethylformamide (DMF) solution in a molar ratio of 1:1, and the total mass fraction of PbI2 and CH3NH3I in the solution is 35wt%. Other steps and methods are the same as those in embodiment 1.

[0110] The device structure obtained in the embodiment of the present invention is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM:m-ITTC / Al. The performance of the device is tested. Under the optimal conditions, the device has a power consumption of 100 mW cm-2 The open circuit voltage under simulated sunlight is 0.81 V and the short circuit current is 13.23 mA cm -2 , the filling factor is 52.25% and the photoelectric conversion efficiency is 5.58%.

[0111] Example 6

[0112] The difference between this embodiment and embodiment 1 is that in step S3, CH3NH3I and PbI2 are dissolved in N,N-dimethylformamide (DMF) solution at a molar ratio of 1:5, the total mass fraction of PbI2 and CH3NH3I in the solution is 50wt%; and the cathode material is Ag. The other steps and methods are the same as those in embodiment 1.

[0113] The device structure obtained in the embodiment of the present invention is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM:m-ITTC / Ag. The performance of the device is tested. Under the optimal conditions, the device has a power consumption of 100 mW cm -2 The open circuit voltage under simulated sunlight is 0.79 V and the short circuit current is 13.76 mA cm -2 , the filling factor is 52.05% and the photoelectric conversion efficiency is 5.68%.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 is that in step S4, a single PCBM solution is used for the organic electron transport layer, and other steps and methods are the same as those in Example 1, which will not be described again.

[0116] The structure of the perovskite solar cell prepared in this control example is ITO / PEDOT:PSS / CH3NH3Pbl3 / PCBM / Al. The performance of the perovskite cell in this control example is tested. -2 The open circuit voltage under simulated sunlight is 0.81 V and the short circuit current is 13.75 mA cm -2 , the filling factor is 55.79% and the photoelectric conversion efficiency is 6.19%.

[0117] The low photoelectric conversion efficiency of the perovskite solar cell is due to defects in the organic electron transport layer, which provide channels for water and oxygen to corrode the active layer. In addition, due to the nature of PCBM itself, it is easy to aggregate, so the coverage with the perovskite layer is poor, which reduces the photoelectric conversion efficiency of the cell.

[0118] In summary, the perovskite solar cell doped with an organic electron transport layer of the present invention comprises, from bottom to top, an anode, a hole transport layer, a perovskite layer, an organic electron transport layer and a cathode, wherein the organic electron transport layer is doped into a PCBM chlorobenzene solution using m-ITTC as a dopant, and the organic electron transport layer is prepared by spin coating the solution. The organic electron transport layer of the present invention can well reduce the probability of electron coupling or charge recombination at the interface, and the photoelectric conversion efficiency of the planar heterojunction perovskite cell prepared by the method reaches 8.37193%, thereby improving the performance of the perovskite solar cell and can be used for photoelectric conversion.

[0119] At the same time, the present invention utilizes a novel dopant m-ITTC to dope a traditional electron transport layer, and the obtained precursor solution is directly spin-coated on the perovskite layer without the need for annealing treatment, which is simple to operate, improves the performance and stability of the device, is low-cost and readily available, and can realize the preparation of large-area thin films.

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an organic electron transport layer, characterized in that: The preparation method comprises the following steps: Step 1, m-ITTC is mixed with PCBM in proportion to form a mixed solution, the mixed solution is placed in chlorobenzene for mixing, and after stirring and filtering, a PCBM:m-ITTC precursor solution is formed; Step 2: spin-coat the PCBM:m-ITTC precursor solution on a coating machine for 20-40 seconds, and form an organic electron transport layer after curing.

2. The method for preparing an organic electron transport layer according to claim 1, characterized in that: The doping concentration of m-ITTC in PCBM in the mixed solution is 0.5-2wt%; In step 1, the stirring time is 12 hours.

3. The method for preparing an organic electron transport layer according to claim 1, characterized in that: The concentration of PCBM:m-ITTC precursor solution was 18-22 mg / ml; The rotation speed of the spin coating on the coating machine is 1500-2500 rpm. 4 . An organic electron transport layer prepared by the method for preparing an organic electron transport layer according to claim 1 .

5. A use of the organic electron transport layer as claimed in claim 4, characterized in that: Application of the organic electron transport layer in the preparation of photovoltaic devices.

6. A method for preparing a perovskite solar cell, characterized in that: The preparation method comprises the following steps: Step S1, cleaning a glass substrate coated with an anode material and treating it with ultraviolet light to obtain a pre-treated substrate substrate; Step S2, depositing PEDOT:PSS on the pretreated substrate, annealing at 130-150° C. for 15-20 min, and then naturally cooling to room temperature to obtain a hole transport layer; Step S3, moving the substrate with the hole transport layer into a glove box, spin-coating a perovskite precursor solution on the hole transport layer using a one-step anti-solvent method, and annealing at 90-100° C. for 10-15 min to obtain a perovskite layer, i.e., an active layer; Step S4, preparing an organic electron transport layer on the perovskite layer; Step S5, depositing a cathode material onto the organic electron transport layer by thermal evaporation under vacuum to obtain an inverted perovskite solar cell; The organic electron transport layer is prepared by the method for preparing an organic electron transport layer as claimed in claim 4.

7. The method for preparing a perovskite solar cell according to claim 6, characterized in that: In step S3, the perovskite precursor solution is prepared by the following method: Dissolving donor A and donor B in an organic solvent and stirring them evenly to obtain a perovskite precursor solution; wherein the donor A is methyl ammonium iodide and the donor B is lead iodide; The organic solvent is N,N-dimethylformamide.

8. The method for preparing a perovskite solar cell according to claim 7, characterized in that: The molar ratio of the donor A to the donor B is 1:(1-5).

9. The method for preparing a perovskite solar cell according to claim 7, characterized in that: The total mass percentage of the donor A and the donor B in the perovskite precursor solution is 35-50wt%.

10. A perovskite solar cell prepared by the method for preparing a perovskite solar cell according to any one of claims 6 to 9.

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