High-performance trans-freestanding perovskite solar cell and preparation method thereof

Abstract

This invention discloses a high-performance inverted perovskite solar cell and its fabrication method. The solar cell sequentially comprises an ITO conductive glass layer, a hole transport layer PTAA, and a MAPbI perovskite layer modified with 3,6-dibromocarbazole. 2.91 Br 0.09 Electron transport layer OAmI, Electron transport layer PC 61 The perovskite active layer consists of a BM (bulk barrier), a hole blocking layer (BCP), and a metal electrode layer (Ag). This approach enhances the carrier transport capability of the perovskite layer by introducing conjugated carbazole molecules into the active layer. This improves the energy level matching between the perovskite and carrier transport layers, increases photocurrent, improves film morphology, balances charge transport, and achieves enhanced photoelectric conversion efficiency, improved stability, and effective suppression of device hysteresis.

Description

A high-performance inverse perovskite solar cell and its fabrication method Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a high-performance inverted perovskite solar cell and its preparation method. Background Technology

[0002] In recent years, to address the increasingly severe energy and environmental problems, people have turned their attention to the development and utilization of new energy sources. Among various new energy technologies, photovoltaic power generation is undoubtedly one of the most promising directions. Although traditional silicon-based solar cells have achieved industrialization and have a relatively mature market, their cost-effectiveness cannot compete with traditional energy sources, and pollution and energy consumption issues in the manufacturing process affect their widespread application. Therefore, it is essential to research and develop new high-efficiency, low-cost solar cells. Among the many new solar cells, a solar cell based on perovskite-type organometal halide CH3NH3PbX (X represents a halogen element, most commonly I) material has attracted worldwide attention.

[0003] Perovskite solar cells, as the third generation of solar cells, have achieved a photoelectric conversion efficiency exceeding 25% within just fourteen years. Compared to other solar cells, perovskite solar cells have advantages such as low cost, high photoelectric conversion efficiency, and simple fabrication process, showing great promise for the future. However, unbalanced charge transport in the perovskite layer and the presence of various defects in the perovskite remain major limiting factors, resulting in unsatisfactory device performance of perovskite solar cells fabricated using conventional methods.

[0004] Inverted perovskite solar cells have attracted widespread attention due to their advantages such as good stability, negligible hysteresis, and high matching degree in tandem cells. However, their photoelectric conversion efficiency is still lower than that of conventional structure devices. This is mainly due to the weaker chemical interaction between the electron transport material and the perovskite, and the poorer energy state structure matching, resulting in greater interfacial recombination losses between the electron transport layer and the perovskite layer, thus leading to a lower open-circuit voltage. In recent years, surface modification of the perovskite layer has been proven to be an effective strategy to suppress interfacial recombination losses.

[0005] Perovskite exhibits relatively poor stability, resulting in a relatively low open-circuit voltage, low electron mobility, and low photocurrent in solar cells. Currently, flexible perovskite solar cells also suffer from poor mechanical stability, primarily due to the low fracture energy of perovskite films. Perovskite films are polycrystalline and contain numerous grain boundaries. The weak bonding at these grain boundaries makes them prone to fracture during bending or stretching, leading to mechanical damage to the entire film.

[0006] This patent proposes a convenient and rapid method for doping perovskite precursor solutions with carbazole-based conjugated molecules, which can improve the carrier transport performance in perovskite thin films, balance charge transport, passivate defects in the thin film, and enhance the optoelectronic performance of the fabricated devices. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a high-performance inverted perovskite solar cell and its fabrication method, which involves doping n-type, highly conductive conjugated organic molecules into MAPbI. 2.91 Br 0.09 Perovskite solar cells with perovskite layers have advantages such as adjusting band structure, improving thin film morphology, reducing defect state density, balancing charge transport, and improving stability.

[0008] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution: a high-performance inverted perovskite solar cell, characterized in that, from bottom to top, it comprises an ITO conductive glass layer, PTAA as a hole transport layer, and MAPbI mixed with carbazole-based small organic molecules (3,6-dibromocarbazole). 2.91 Br 0.09 Perovskite, OAmI as an electron transport layer, PC as an electron transport layer 61 BM, 2,9-dimethyl-4,7-biphenyl-1,10-o-phenanthroline (BCP) as a hole blocking layer, and a silver metal electrode layer.

[0009] Furthermore, the 3,6-dibromocarbazole-doped MAPbI 2.91 Br 0.09 The preparation process of perovskite is as follows:

[0010] PbI2, MAI, and MABr were dissolved in methylamine ethanol solution and acetonitrile solution, and stirred at room temperature until completely dissolved. The solution was filtered through an organic filter membrane into a sample vial, and 3,6-dibromocarbazole ethanol solution was added to complete the preparation of the perovskite precursor solution.

[0011] Furthermore, the 3,6-dibromocarbazole-doped MAPbI 2.91 Br 0.09 The preparation process of perovskite is as follows:

[0012] PbI₂, MAI, and MABr in a molar ratio of 1:0.97:0.03 were dissolved in a 1:1 volume ratio of methylamine ethanol solution and acetonitrile solution, and stirred at room temperature until completely dissolved to form a 1.2 M solution. The solution was filtered through a 0.22 μm organic filter membrane into a sample vial, and a 20 mg / mL concentration of 3,6-dibromocarbazole ethanol solution was added to complete the preparation of the perovskite precursor solution.

[0013] Another object of the present invention is to provide a method for preparing a high-performance inverted perovskite solar cell, characterized by comprising the following steps:

[0014] S1: Use dish soap, isopropanol, deionized water and anhydrous ethanol in sequence to ultrasonically clean the ITO glass substrate for 15-20 minutes each time; after drying in the drying oven, clean it with a UV ozone cleaner for 40-45 minutes and then take it out for use.

[0015] S2: Spin-coat the hole transport layer PTAA onto the cleaned ITO glass substrate, and then anneal at 95-105 degrees Celsius for 10-15 minutes;

[0016] S3: Dynamically spin-coating 3,6-dibromocarbazole-doped MAPbI onto the hole transport layer PTAA at 6000–6500 rpm. 2.91 Br 0.09 The perovskite precursor solution was then annealed at 95–105 degrees Celsius for 10 minutes.

[0017] S4: Dynamically spin-coat the electron transport layer OAmI on the perovskite layer at 6000-6500 rpm without annealing;

[0018] S5: Static spin coating of electron transport layer PCBM is performed on electron transport layer OAmI layer at 1500-2000 rpm without annealing;

[0019] S6: Dynamic spin coating of hole blocking layer BCP onto electron transport layer PCBM, without annealing;

[0020] S7: Deposit a metal electrode Ag onto the hole blocking layer in a vacuum coating machine, with a thickness of 110-130 nm.

[0021] Further steps include the following:

[0022] S1: Use dish soap, isopropanol, deionized water and anhydrous ethanol in sequence to ultrasonically clean the ITO glass substrate for 15 minutes each time; after drying in the drying oven, clean it with a UV ozone cleaner for 40 minutes and then take it out for use.

[0023] S2: Spin-coat the hole transport layer PTAA onto the cleaned ITO glass substrate, and then anneal at 100 degrees Celsius for 10 min;

[0024] S3: Dynamic spin-coating of 3,6-dibromocarbazole-doped MAPbI onto the hole transport layer PTAA at 6000 rpm. 2.91 Br 0.09 The perovskite precursor solution was then annealed at 100 degrees Celsius for 10 minutes.

[0025] S4: The electron transport layer OAmI is dynamically spin-coated onto the perovskite layer at 6000 rpm without annealing;

[0026] S5: Electron transport layer PCBM is statically spin-coated onto the electron transport layer OAmI at 1500 rpm without annealing;

[0027] S6: Dynamic spin coating of hole blocking layer BCP onto electron transport layer PCBM, without annealing;

[0028] S7: Deposit a metal electrode Ag of 120 nm onto the hole blocking layer in a vacuum coating machine.

[0029] The beneficial effects of this invention are:

[0030] (1) In this invention, carbazole conjugated small molecules are introduced into the perovskite precursor solution, which changes the energy level structure of the perovskite layer, improves the stability and open circuit voltage of the perovskite, and also enhances the electron mobility of the solar cell, thereby improving the photocurrent of the perovskite solar cell.

[0031] (2) In this invention, the doping of the carbazole-type conjugated organic small molecule 3,6-dibromocarbazole in the perovskite light-absorbing layer can not only improve the photocurrent of the perovskite device, but also effectively balance the transmission of electrons and holes, and promote the exciton dissociation and carrier migration distance in the perovskite light-absorbing material.

[0032] (3) In this invention, the presence of 3,6-dibromocarbazole promotes the growth of perovskite crystal thin films, passivates defects in the perovskite layer, improves the morphology of the thin film, reduces the defect states of the thin film, thereby suppressing the hysteresis effect of the device and improving the device performance. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 is a statistical graph of photoelectric conversion efficiency for Examples 1, 2, 3 and 4;

[0035] Figure 2 shows the device parameter distribution diagrams for Examples 1, 2, 3, and 4;

[0036] Figure 3 shows the PL and TRPL diagrams for Examples 1, 2, 3, and 4;

[0037] Figure 4 shows the DFT theoretical calculation diagrams for Examples 1, 2, 3, and 4;

[0038] Figure 5 shows the forward and reverse scan JV curves for Examples 1 and 4;

[0039] Figure 6 shows the energy level diagrams of the perovskite layer and adjacent carrier transport layer in Examples 1, 2, 3 and 4.

[0040] Figure 7 shows the humidity stability curves for Examples 1, 2, 3 and 4. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] The structure of a high-performance inverted perovskite solar cell, from bottom to top, is as follows:

[0044] ITO / PTAA / MAPbI 2.91 Br 0.09 / OAmI / PC 61 BM / BCP / Ag

[0045] The preparation method is as follows:

[0046] S1: The ITO glass substrate is ultrasonically cleaned sequentially with dish soap, isopropanol, deionized water, and anhydrous ethanol, each cleaning session lasting 15 minutes. After drying in a drying oven, it is then cleaned with a UV ozone cleaner for 40 minutes before being removed and set aside.

[0047] S2: Spin-coat the hole transport layer PTAA onto the cleaned ITO glass substrate, and then anneal at 100 degrees Celsius for 10 min;

[0048] S3: Dynamic spin coating of MAPbI at 6000 rpm onto the hole transport layer PTAA. 2.91 Br 0.09 The perovskite precursor solution was then annealed at 100 degrees Celsius for 10 minutes.

[0049] S4: The electron transport layer OAmI is dynamically spin-coated onto the perovskite layer at 6000 rpm without annealing;

[0050] S5: Static spin coating of electron transport layer PC onto electron transport layer OAmI layer at 1500 rpm.61 BM, no annealing required;

[0051] S6: In the electron transport layer PC 61 Dynamic spin-coating of hole blocking layer BCP on BM, no annealing required;

[0052] S7: Deposit a metal electrode Ag of 120 nm onto the hole blocking layer in a vacuum coating machine.

[0053] Example 2

[0054] The structure of a high-performance inverted perovskite solar cell, from bottom to top, is as follows:

[0055] ITO / PTAA / MAPbI 2.91 Br 0.09 (Carbazole) / OAmI / PC 61 BM / BCP / Ag

[0056] The preparation method is as follows:

[0057] S1: The ITO glass substrate is ultrasonically cleaned sequentially with dish soap, isopropanol, deionized water, and anhydrous ethanol, each cleaning session lasting 15 minutes. After drying in a drying oven, it is then cleaned with a UV ozone cleaner for 40 minutes before being removed and set aside.

[0058] S2: Spin-coat the hole transport layer PTAA onto the cleaned ITO glass substrate, and then anneal at 100 degrees Celsius for 10 min;

[0059] S3: Carbazole-doped MAPbI was dynamically spin-coated onto the hole transport layer PTAA at 6000 rpm. 2.91 Br 0.09 The perovskite precursor solution was then annealed at 100 degrees Celsius for 10 minutes.

[0060] S4: The electron transport layer OAmI is dynamically spin-coated onto the perovskite layer at 6000 rpm without annealing;

[0061] S5: Static spin coating of electron transport layer PC onto electron transport layer OAmI layer at 1500 rpm. 61 BM, no annealing required;

[0062] S6: In the electron transport layer PC 61 Dynamic spin-coating of hole blocking layer BCP on BM, no annealing required;

[0063] S7: Deposit a metal electrode Ag of 120 nm onto the hole blocking layer in a vacuum coating machine.

[0064] Example 3

[0065] The structure of a high-performance inverted perovskite solar cell, from bottom to top, is as follows:

[0066] ITO / PTAA / MAPbI 2.91 Br 0.09 (2,7-dibromocarbazole) / OAmI / PC 61 BM / BCP / Ag

[0067] The preparation method is as follows:

[0068] S1: The ITO glass substrate is ultrasonically cleaned sequentially with dish soap, isopropanol, deionized water, and anhydrous ethanol, each cleaning session lasting 15 minutes. After drying in a drying oven, it is then cleaned with a UV ozone cleaner for 40 minutes before being removed and set aside.

[0069] S2: Spin-coat the hole transport layer PTAA onto the cleaned ITO glass substrate, and then anneal at 100 degrees Celsius for 10 min;

[0070] S3: MAPbI doped with 2,7-dibromocarbazole (20 mg / ml ethanol solution) was dynamically spin-coated onto the hole transport layer PTAA at 6000 rpm. 2.91 Br 0.09 The perovskite precursor solution was then annealed at 100 degrees Celsius for 10 minutes.

[0071] S4: The electron transport layer OAmI is dynamically spin-coated onto the perovskite layer at 6000 rpm without annealing;

[0072] S5: Static spin coating of electron transport layer PC onto electron transport layer OAmI layer at 1500 rpm. 61 BM, no annealing required;

[0073] S6: In the electron transport layer PC 61 Dynamic spin-coating of hole blocking layer BCP on BM, no annealing required;

[0074] S7: Deposit a metal electrode Ag of 120 nm onto the hole blocking layer in a vacuum coating machine.

[0075] Example 4

[0076] The structure of a high-performance inverted perovskite solar cell, from bottom to top, is as follows:

[0077] ITO / PTAA / MAPbI 2.91 Br 0.09 (3,6-dibromocarbazole) / OAmI / PC 61 BM / BCP / Ag

[0078] The preparation method is as follows:

[0079] S1: The ITO glass substrate is ultrasonically cleaned sequentially with dish soap, isopropanol, deionized water, and anhydrous ethanol, each cleaning session lasting 15 minutes. After drying in a drying oven, it is then cleaned with a UV ozone cleaner for 40 minutes before being removed and set aside.

[0080] S2: Spin-coat the hole transport layer PTAA onto the cleaned ITO glass substrate, and then anneal at 100 degrees Celsius for 10 min;

[0081] S3: MAPbI doped with 3,6-dibromocarbazole (20 mg / ml) was dynamically spin-coated onto the hole transport layer PTAA at 6000 rpm. 2.91 Br 0.09 The perovskite precursor solution was then annealed at 100 degrees Celsius for 10 minutes.

[0082] S4: The electron transport layer OAmI is dynamically spin-coated onto the perovskite layer at 6000 rpm without annealing;

[0083] S5: Static spin coating of electron transport layer PC onto electron transport layer OAmI layer at 1500 rpm. 61 BM, no annealing required;

[0084] S6: In the electron transport layer PC 61 Dynamic spin-coating of hole blocking layer BCP on BM, no annealing required;

[0085] S7: Deposit a metal electrode Ag of 120 nm onto the hole blocking layer in a vacuum coating machine.

[0086] As shown in Figure 1, the photoelectric conversion efficiency of perovskite devices can be significantly improved by introducing 3,6-dibromocarbazole. When the amount of 3,6-dibromocarbazole introduced is 1:100 with the volume ratio of the perovskite precursor liquid, the photoelectric conversion efficiency of the perovskite solar cell device can be increased by more than 10%.

[0087] As shown in Figure 2, the device prepared by modification with 3,6-dibromocarbazole showed improvements in all performance parameters, with the final photoelectric conversion efficiency increasing by more than 10% compared to the blank control group.

[0088] As shown in Figure 3, the perovskite film modified with 3,6-dibromocarbazole has a better photoresponse signal and a longer carrier migration rate, which proves that the modified film has a lower defect state density.

[0089] As shown in Figure 4, DFT calculations indicate that the adsorption energy of 2,7-dibromocarbazole is much lower than that of carbazole and 3,6-dibromocarbazole, resulting in its interaction with the perovskite lattice being mainly adsorption. This intensifies the lateral transport within the perovskite crystal, leading to a large number of carrier recombinations. In contrast, 3,6-dibromocarbazole has a lower binding energy, and its main mode of interaction is binding, which enhances the longitudinal transport within the perovskite crystal and improves the transport performance of the thin film.

[0090] As shown in Figure 5, the photocurrent hysteresis in the inverted solar cell modified with 3,6-dibromocarbazole is significantly lower than that in the perovskite device of the mixed blank control group. The significant reduction in photocurrent hysteresis can be attributed to the reduction in the number of defects and the adjustment and alignment of energy levels.

[0091] As shown in Figure 6, the energy levels of the perovskite film modified with 3,6-dibromocarbazole are more matched with the carrier transport layers on both sides, which usually results in higher open-circuit voltage and higher carrier mobility, both of which have been demonstrated by previous characterization.

[0092] As shown in Figure 7, the humidity stability of the inverted solar cell modified with 3,6-dibromocarbazole is far superior to that of the blank control group. It can maintain more than 85% of its original efficiency even after being stored in an atmosphere with an atmospheric humidity of about 30% for more than 50 days. The improved stability can be attributed to the reduction of the defect state density inside the perovskite film and the better energy level matching.

Claims

1. A reverse perovskite solar cell, characterized in that, From bottom to top, the structure includes an ITO conductive glass layer, PTAA as a hole transport layer, MAPbI2.91Br0.09 perovskite mixed with carbazole-based organic small molecules 3,6-dibromocarbazole and 3,6-dibromocarbazole, OAmI as an electron transport layer, PC61BM as an electron transport layer, 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline BCP as a hole blocking layer, and a silver metal electrode layer.

2. The inverted perovskite solar cell according to claim 1, characterized in that, The preparation process of the 3,6-dibromocarbazole-doped MAPbI2.91Br0.09 perovskite is as follows: PbI2, MAI and MABr are dissolved in methylamine ethanol solution and acetonitrile solution, and stirred at room temperature until completely dissolved; the solution is filtered into a sample bottle through an organic filter membrane, and 3,6-dibromocarbazole ethanol solution is added to complete the preparation of the perovskite precursor solution.

3. The inverted perovskite solar cell according to claim 2, characterized in that, The preparation process of the 3,6-dibromocarbazole-doped MAPbI2.91Br0.09 perovskite is as follows: PbI2, MAI, and MABr in a molar ratio of 1:0.97:0.03 are dissolved in a methylamine ethanol solution and an acetonitrile solution in a volume ratio of 1:1, and stirred at room temperature until completely dissolved to form a 1.2M solution; the solution is filtered through a 0.22μm organic filter membrane into a sample vial, and a 20mg / mL concentration of 3,6-dibromocarbazole ethanol solution with a volume ratio of 1% is added to complete the preparation of the perovskite precursor solution.

4. A method for fabricating an inverted perovskite solar cell, characterized in that, The process includes the following steps: S1: The ITO glass substrate is ultrasonically cleaned sequentially with detergent, isopropanol, deionized water, and anhydrous ethanol, each cleaning lasting 15–20 minutes; after drying in a drying oven, it is cleaned with a UV ozone cleaner for 40–45 minutes and then removed for later use; S2: A hole transport layer PTAA is spin-coated onto the cleaned ITO glass substrate, followed by annealing at 95–105 degrees Celsius for 10–15 minutes; S3: 3,6-dibromocarbazole-doped MAPbI2.91B is dynamically spin-coated onto the hole transport layer PTAA at 6000–6500 rpm. R0.09 perovskite precursor solution, followed by annealing at 95-105 degrees Celsius for 10 min; S4: Dynamically spin-coat electron transport layer OAmI on the perovskite layer at 6000-6500 rpm, no annealing required; S5: Statically spin-coat electron transport layer PCBM on the electron transport layer OAmI at 1500-2000 rpm, no annealing required; S6: Dynamically spin-coat hole blocking layer BCP on the electron transport layer PCBM, no annealing required; S7: Evaporate metal electrode Ag to the hole blocking layer in a vacuum coating machine, with a thickness of 110-130 nm.

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