Bromine-containing perovskite light absorption layer, preparation method and application thereof
By introducing urea phosphate additives into tandem perovskite solar cells to regulate the crystallization process, the problem of quality degradation of wide-bandgap perovskite thin films was solved, and the photoelectric conversion efficiency and stability were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING UNIV
- Filing Date
- 2026-01-16
- Publication Date
- 2026-05-15
AI Technical Summary
In the development of tandem perovskite solar cells, the increased Br content in wide-bandgap perovskites leads to a decrease in crystal quality, an increase in thin film defect density, and severe on-state voltage loss, affecting photoelectric conversion efficiency and stability.
A bromine-containing perovskite light-absorbing layer was prepared by coating a precursor solution in an air atmosphere and annealing it, using bromine-containing perovskite structural material as raw material and urea phosphate additive. The phosphate and urea groups in urea phosphate passivated defects, and the crystallization process was adjusted to improve the crystallization quality of the film.
It effectively reduces surface defects in thin films, improves photoelectric conversion efficiency, increases open-circuit voltage and fill factor, enhances battery stability, and increases photoelectric conversion efficiency from 17.40% to 18.21%.
Smart Images
Figure CN122054900A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solar cell technology, specifically relating to a bromine-containing perovskite light-absorbing layer, its preparation method, and its application. Background Technology
[0002] In the solar cell market, crystalline silicon solar cells are the mainstream application, accounting for over 95% of the photovoltaic market share. However, after decades of continuous development, their photoelectric conversion efficiency has approached its theoretical limit, and the potential for further reduction in commercialization costs is also nearing a bottleneck. This will be a major challenge for crystalline silicon solar cells in the future. Against this backdrop, perovskite solar cells have experienced rapid development in the last decade or so due to their continuously tunable bandgap, excellent carrier transport performance, and the ability to be fabricated using low-cost solution methods. Their efficiency has continued to climb, increasing from 3.8% to over 27% today, making them comparable to current commercially available crystalline silicon solar cells.
[0003] However, due to the Shockley-Queisser limit (SQ limit), the efficiency of single-junction solar cells has gradually reached a bottleneck, making significant efficiency breakthroughs extremely difficult. To further improve the photoelectric conversion efficiency of solar cells, tandem solar cells have emerged. Tandem solar cells are a type of cell fabricated by stacking semiconductor light-absorbing materials with different bandgap widths. Their main working principle is to utilize semiconductor materials with different bandgap widths to absorb sunlight within a specific wavelength range. This design effectively reduces the hot carrier relaxation loss generated by single-junction cells when absorbing short wavelengths, improving the utilization rate of the solar spectrum and thus breaking the SQ limit of single-junction cells. The theoretical limit efficiency of two-junction tandem cells is as high as 43%. Because perovskite materials possess excellent photoelectric properties and tunable bandgap characteristics, they are an ideal choice for fabricating high-efficiency tandem solar cells. Therefore, researching tandem perovskite solar cells and promoting their future commercial development is of great significance.
[0004] However, the development of tandem perovskite solar cells faces numerous technical challenges. To achieve high-efficiency all-perovskite tandem solar cells, the optimal bandgap matching is to use a wide bandgap perovskite of approximately 1.8 eV and a narrow bandgap perovskite of approximately 1.2 eV. For the wide bandgap perovskite of approximately 1.8 eV, its Br content is relatively high. However, due to the low solubility of bromides in DMF and DMSO solvents, increasing their content accelerates the crystallization rate of perovskite. Therefore, a higher Br content generally reduces the film quality of perovskite. Furthermore, excessive Br content (>15%) causes perovskite lattice distortion, leading to a decrease in defect formation energy and an increased likelihood of defects. Thus, with further increases in Br content, the defect density of the perovskite film also increases, resulting in increasingly larger open-circuit voltage losses. Consequently, the open-circuit voltage of the wide bandgap perovskite cell does not increase proportionally with the increase in bandgap.
[0005] To address these issues, it is crucial to design a method that enhances the crystal quality of the bromine-containing perovskite absorber layer and improves the photoelectric conversion efficiency and operational stability of tandem perovskite solar cells. Summary of the Invention
[0006] One objective of this invention is to provide a bromine-containing perovskite light-absorbing layer, the raw materials for which include bromine-containing perovskite structural materials and additives; The additive contains two groups: urea and phosphate.
[0007] Furthermore, the additive is urea phosphate.
[0008] Furthermore, the chemical formula of the bromide-containing perovskite structure material is ABX3, wherein A includes Cs. + FA + or MA + B includes any one or at least two of the following, where B includes Pb. 2+ X includes Br - and I - In X, Br - The content is greater than 15%.
[0009] In one specific embodiment of the present invention, the raw material containing bromine perovskite structure is obtained by dissolving FAI, CsI, PbBr2, and PbI2 in a solvent.
[0010] Furthermore, the ratio of the raw material and additives containing bromine perovskite structure is 1.4 mol: 0.4-1 g.
[0011] The second objective of this invention is to provide a method for preparing the above-mentioned bromine-containing perovskite light-absorbing layer, specifically: in an air atmosphere, a bromine-containing perovskite precursor solution is coated on the surface of a substrate, and after the solvent evaporates, an annealing treatment is performed to obtain the bromine-containing perovskite light-absorbing layer. The bromine-containing perovskite precursor solution includes a solute and a solvent, wherein the solute includes bromine-containing perovskite structural material raw materials and additives.
[0012] Furthermore, in the bromine-containing perovskite precursor solution, the concentration of the bromine-containing perovskite structural material raw material is 1.4 mol / L, and the concentration of the additive is 0.4-1 mg / ml.
[0013] Furthermore, the solvent includes any one or a combination of at least two of dimethyl sulfoxide, 2-methoxyethanol, N,N-dimethylformamide, N-methylpyrrolidone, or acetonitrile.
[0014] The third objective of this invention is to provide a bromine-containing perovskite solar cell, which, from the light-receiving front side to the light-receiving back side, comprises: a transparent conductive substrate, a hole transport layer, the aforementioned bromine-containing perovskite light-absorbing layer, an electron transport layer, and a metal electrode.
[0015] Furthermore, the transparent conductive substrate is an indium tin oxide substrate, an indium tungsten oxide substrate, a fluorine-doped tin oxide substrate, an indium zinc oxide substrate, or an aluminum-doped zinc oxide substrate.
[0016] Furthermore, the selected hole transport layer is made of a p-type semiconductor material, selected from nickel oxide (NiO). x Molybdenum oxide (MoO3), cuprous oxide (Cu2O), cuprous iodide (CuI), copper phthalocyanine (CuPc), cuprous thiocyanate (CuSCN), redox graphene, poly(triaryl amine) (PTAA), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly(3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), poly(4-phenyl)(4-butylphenyl)amine (Ploy-TPD), monolayers, and one or more of the following.
[0017] Furthermore, the selected electron transport layer is made of an n-type semiconductor material, selected from titanium dioxide (TiO2), tin oxide (SnO2), zinc oxide (ZnO), vanadium oxide (V2O5), zinc tin oxide (Zn2SnO4), and fullerene (C). 60 Combinations of one or more materials such as graphene, fullerene derivative [6,6]-phenyl-C61-butyrate methyl ester (PCBM).
[0018] Furthermore, the metal electrode can be prepared using one or more of the following metal materials: gold, palladium, silver, titanium, chromium, nickel, aluminum, copper, etc.; the preparation method of the metal electrode can be vacuum evaporation, sputtering, atomic layer deposition, 3D printing, screen printing, inkjet printing, etc.
[0019] The above-mentioned method for preparing bromine-containing perovskite solar cells includes the following steps: Depositing a hole transport layer on a transparent conductive substrate A bromine-containing perovskite light-absorbing layer is deposited on the hole transport layer. An electron transport layer is deposited on the aforementioned bromine-containing perovskite light-absorbing layer. A metal electrode is deposited on the electron transport layer.
[0020] In this invention, the transparent conductive substrate, hole transport layer, bromide-containing perovskite light-absorbing layer, electron transport layer and metal electrode can all be fabricated using methods familiar to those skilled in the art, such as electron beam evaporation, thermal evaporation, magnetron sputtering, atomic layer deposition, spin coating, and blade coating.
[0021] This invention introduces additives that regulate crystallization and passivate defects during the preparation of the bromine-containing perovskite light-absorbing layer, thereby increasing the crystal size of the bromine-containing perovskite light-absorbing layer film, improving its crystal quality, reducing surface defects, effectively reducing the turn-on voltage loss of bromine-containing perovskite solar cell devices, and simultaneously improving the photoelectric conversion efficiency of bromine-containing perovskite cells.
[0022] In one embodiment of the present invention, the additive for adjusting crystallization and passivating defects is urea phosphate, which passivates Pb commonly found in bromine-containing perovskites through the two functional groups (phosphate and urea groups) contained therein. 2+ ,Br - Among them, phosphate and Pb 2+ Forming strong coordination bonds (Pb-OP), the urea group reacts with Br. - Formation of hydrogen bonds (NH...Br) - These interactions allow urea phosphate to effectively "bind" the precursor ions, significantly slowing down the crystallization kinetics and thus regulating the crystallization quality of the bromide-containing perovskite light-absorbing layer. Simultaneously, phosphate, as a strong Lewis base, interacts with uncoordinated Pb... 2+ Coordination (generated from lead vacancies or dangling bonds at grain boundaries) passesivates deep-level defects. The urea group, acting as a hydrogen bond donor, can not only bind to free Br⁻ but also effectively fill bromine vacancies. NH₃ binds to Pb surrounding the vacancies. 2+The weak interactions can neutralize the charge of defects, transforming them from deep energy levels to shallow energy levels or even eliminating them. This ultimately solves the problem of severe non-radiative recombination caused by the high bromine content in bromine-containing perovskite light-absorbing layers: easier formation of deep-level defects leading to huge open-circuit voltage losses. It effectively reduces the porosity on the surface of wide-bandgap perovskite light-absorbing layers, reduces perovskite defects, lowers the recombination rate of electrons and holes, improves carrier lifetime, and fabricates more dense perovskite films, thereby enhancing the performance of bromine-containing perovskite solar cells.
[0023] Finally, this method was applied to a depth of 0.049 cm. 2 In the fabrication of bromide-containing perovskite solar cells with an effective area, the photoelectric conversion efficiency was increased from 17.40% to 18.21%. Furthermore, this method was applied to a 0.049 cm² solar cell. 2 In the fabrication of the effective area of the two-junction tandem perovskite solar cell, the photoelectric conversion efficiency was increased from 26.80% to 28.58%. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the device structure of a bromine-containing perovskite solar cell.
[0025] Figure 2 In-situ optical micrographs of bromide-containing perovskite thin film crystals for the control and optimized samples.
[0026] Figure 3 These are scanning electron microscope images of the control and optimized samples.
[0027] Figure 4 X-ray diffraction patterns of the control and optimized samples.
[0028] Figure 5 Fluorescence spectra of the control sample and the optimized sample.
[0029] Figure 6 The current density-voltage curves are for the control and optimized samples of bromide-containing perovskite solar cells. Detailed Implementation
[0030] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.
[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0032] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Comparative Example 1
[0033] This embodiment is a control sample of a bromine-containing perovskite solar cell, using... Figure 1 The device structure shown is fabricated using the following specific process: (1) ITO glass was used as a transparent conductive substrate. It was ultrasonically cleaned in deionized water and isopropanol for 15 min in sequence, then dried with N2, and finally placed in an ultraviolet ozone cleaner for 15 min to remove the organic residues on the substrate surface and increase the surface wettability.
[0034] (2) Carrier transport layer 1 was prepared by NiO nanoparticles. NiO nanoparticles prepared by hydrothermal method were dispersed in an appropriate amount of deionized water with a concentration of 10 mg / mL. After stirring evenly, the mixture was coated onto the ITO bottom electrode and then annealed in air at 100 °C for 10 min to obtain a NiO film with a thickness of 20-30 nm as a hole transport layer.
[0035] (3) Using FA 0.65 Cs 0.35 PbI 1.8 Br 1.2 As a material for a bromine-containing perovskite light-absorbing layer, FA is weighed by molar ratio in a glove box filled with inert gases such as nitrogen. 0.8 Cs 0.2 PbI 1.95 Br 1.05 The perovskite was prepared by dissolving the weighed reagent in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) at a volume ratio of 9:1, and stirring for 8 hours. A brominated perovskite light-absorbing layer was then prepared by a blade coating method in a glove box and annealed on a hot plate at 100°C for 20 min to obtain the crystallized brominated perovskite light-absorbing layer.
[0036] (4) In a nitrogen glove box, using a vacuum thermal evaporation method, a 20 nm thick C layer was evaporated onto the surface of the prepared bromine-containing perovskite light-absorbing layer in a high vacuum environment. 60 As an electron transport layer.
[0037] (5) In a nitrogen glove box, vacuum thermal evaporation is used to deposit C in a high vacuum environment. 60 A 150 nm copper layer can be thermally deposited on the electron transport layer as a metal electrode to obtain a bromine-containing perovskite solar cell device.
[0038] The prepared bromine-containing perovskite solar cells were tested and packaged in a nitrogen glove box. Example 1
[0039] This embodiment is an optimized sample of a tandem perovskite solar cell, employing... Figure 1 The device structure shown is fabricated using the following specific process: (1) ITO glass was used as a transparent conductive substrate. It was ultrasonically cleaned in deionized water and isopropanol for 15 min in sequence, then dried with N2, and finally placed in an ultraviolet ozone cleaner for 15 min to remove the organic residues on the substrate surface and increase the surface wettability.
[0040] (2) Taking NiO nanoparticles as an example, carrier transport layer 1 is prepared by dispersing the NiO nanoparticles prepared by hydrothermal method into an appropriate amount of deionized water with a concentration of 10 mg / mL (about 0.2 mmol / mL). After stirring evenly, the mixture is coated onto the bottom electrode and then annealed in air at 100 °C for 10 min to obtain a NiO film with a thickness of 20-30 nm as a hole transport layer.
[0041] (3) Using FA 0.65 Cs 0.35 PbI 1.8 Br 1.2 As a material for a bromine-containing perovskite light-absorbing layer, FA is weighed by molar ratio in a glove box filled with inert gases such as nitrogen. 0.65 Cs 0.35 PbI 1.8 Br 1.2 The perovskite, then weigh 0.1 mg of urea phosphate and add it to the weighed FA. 0.65 Cs 0.35 PbI 1.8 Br 1.2 The perovskite was then dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) at a volume ratio of 9:1. The final FA was prepared. 0.65 Cs 0.35 PbI 1.8 Br 1.2 The perovskite concentration was 1.4 mmol, and the mixture was stirred for 8 hours. A brominated perovskite light-absorbing layer was prepared in a glove box using a blade coating method, and then annealed on a hot plate at 100°C for 15 min to obtain the crystallized brominated perovskite light-absorbing layer.
[0042] (4) In a nitrogen glove box, using a vacuum thermal evaporation method, a 20 nm thick C layer was evaporated onto the prepared bromine-containing perovskite light-absorbing layer in a high vacuum environment. 60 As an electron transport layer.
[0043] (5) In a nitrogen glove box, vacuum thermal evaporation is used to deposit C in a high vacuum environment. 60A 150 nm copper layer can be thermally deposited on the electron transport layer as a metal electrode to obtain a bromine-containing perovskite solar cell device.
[0044] The prepared bromine-containing perovskite solar cells were tested and packaged in a nitrogen glove box.
[0045] Figure 2 In-situ optical micrographs of the crystallization of brominated perovskite films are presented, showing the control and optimized samples. Over time, the optimized sample exhibits a slower crystallization rate and fewer nucleation sites compared to the control, indicating that the brominated perovskite films have better crystallization quality after the introduction of urea phosphate.
[0046] Figure 3 X-ray diffraction patterns of bromide-containing perovskite films are shown for the control and optimized samples. Compared to the control sample, the peak values of the characteristic peaks in the optimized sample are significantly increased, indicating that the optimized film has a larger crystal size, higher crystallinity, and better long-range order in its crystal structure, resulting in a stronger diffraction signal.
[0047] Figure 4 Scanning electron microscope images of the control and optimized samples are shown. Pore formation can be observed on the surface of the control sample, while the surface of the optimized sample is more uniform and dense. This indicates that the introduction of urea phosphate can inhibit the formation of pores on the surface of bromine-containing perovskite, effectively suppress lead iodide precipitation, improve interfacial properties, enhance battery stability, and increase photoelectric conversion efficiency.
[0048] Figure 5 The fluorescence spectra of the control and optimized samples show that the introduction of urea phosphate can further reduce perovskite defects, lower the recombination rate of electrons and holes, and improve carrier lifetime.
[0049] Figure 6 The current density-voltage curves of a control sample and an optimized sample of a bromide-containing perovskite solar cell are shown. The optimized sample exhibits a higher open-circuit voltage (V0.05) compared to the control sample. OC This improves the conversion efficiency of perovskite solar cells by increasing the fill factor (FF) and fill factor (FF) at 0.049 cm⁻¹. 2 In the fabrication of bromide-containing perovskite solar cells with effective area, the photoelectric conversion efficiency was increased from 17.40% to 18.21%.
Claims
1. A perovskite-containing light-absorbing layer, characterized in that, The raw materials for preparation include bromide-containing perovskite structural materials and additives; The additive contains two groups: urea and phosphate.
2. The bromine-containing perovskite light-absorbing layer according to claim 1, characterized in that, The additive is urea phosphate.
3. The bromine-containing perovskite light-absorbing layer according to claim 1, characterized in that, The chemical formula of the bromine-containing perovskite-structured raw material is ABX3, where A includes Cs. + FA + or MA + B includes any one or at least two of the following, where B includes Pb. 2+ X includes Br - and I - In X, Br - The content is greater than 15%.
4. The bromine-containing perovskite light-absorbing layer according to claim 1, characterized in that, The ratio of the raw material and additives containing bromine perovskite structure is 1.4 mol: 0.4-1 g.
5. The method for preparing the bromine-containing perovskite light-absorbing layer according to any one of claims 1-4, characterized in that, In an air atmosphere, a bromine-containing perovskite precursor solution is coated on the substrate surface. After the solvent evaporates, an annealing treatment is performed to obtain the bromine-containing perovskite light-absorbing layer. The bromine-containing perovskite precursor solution includes a solute and a solvent, wherein the solute includes bromine-containing perovskite structural material raw materials and additives.
6. The preparation method according to claim 5, characterized in that, In the bromine-containing perovskite precursor solution, the concentration of the bromine-containing perovskite structural material raw material is 1.4 mol / L, and the concentration of the additive is 0.4-1 mg / ml.
7. The preparation method according to claim 5, characterized in that, The solvent includes any one or a combination of at least two of the following: dimethyl sulfoxide, 2-methoxyethanol, N,N-dimethylformamide, N-methylpyrrolidone, or acetonitrile.
8. A perovskite solar cell containing bromine, characterized in that, From the light-receiving front side to the light-receiving back side, it comprises, in sequence: a transparent conductive substrate, a hole transport layer, a bromine-containing perovskite light-absorbing layer as described in any one of claims 1-4, an electron transport layer, and a metal electrode.
9. The bromine-containing perovskite solar cell according to claim 8, characterized in that, The transparent conductive substrate is an indium tin oxide substrate, an indium tungsten oxide substrate, a fluorine-doped tin oxide substrate, an indium zinc oxide substrate, or an aluminum-doped zinc oxide substrate.