Method for inhibiting phase separation of broadband gap mixed halide perovskite solar cell

Abstract

The invention discloses a method for inhibiting phase separation of a broad-band gap mixed halide perovskite solar cell, belongs to the technical field of perovskite solar cell preparation, and aims to realize phase separation inhibition by changing components of a perovskite precursor solution so as to reduce thin film defect state density and homogenize thin film stress distribution. According to the invention, a certain amount of polymer solution is added into the perovskite precursor solution, and then the perovskite layer is prepared in the form of mixed solution; the polymer in the prepared perovskite layer forms a barrier at the grain boundary of the perovskite thin film, and the polymer additive can play an interception role at the grain boundary of the perovskite thin film, so that aggregation of same halide ions is reduced, and a phase separation phenomenon is inhibited.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite solar cell preparation, and in particular relates to a method for inhibiting phase separation of a wide bandgap mixed halide perovskite solar cell. Background Art

[0002] In the context of dual carbon, solar energy is expected to account for more than 25% of primary energy consumption in the future. As a renewable energy source, solar energy has been valued by society and has a promising market prospect. In recent years, perovskite solar cells, as a new type of photovoltaic technology, have developed rapidly in terms of stability and efficiency. They have significant advantages such as superior photoelectric conversion characteristics and adjustable band gap, and have great development prospects.

[0003] In perovskite-crystalline silicon tandem solar cells, the perovskite layer as the top cell has a wide band gap. After being stacked with the bottom cell crystalline silicon layer, it can break through the efficiency limit (SQ limit) of a single-layer perovskite solar cell. However, since wide-bandgap perovskite solar cells contain multiple halides such as bromine and iodide ions in their composition, the above halides are prone to phase separation during the continuous application of light to the cells. That is, the bromine and iodine ions that were originally distributed in a uniform lattice under dark conditions will migrate across the grain boundaries in the perovskite film to form bromine and iodine-enriched areas, respectively, which have a serious impact on the efficiency and stability of the cell. Therefore, phase separation is a difficult problem that needs to be solved urgently in the application of wide-bandgap perovskite solar cells. Summary of the invention

[0004] The present invention provides a method for inhibiting phase separation of wide bandgap mixed halide perovskite solar cells, by adding a polymer additive to a perovskite solution to inhibit the migration process of bromide ions and iodide ions at grain boundaries, reduce the defect state density, and homogenize the film stress distribution, thereby achieving improved efficiency and stability of the solar cell.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A method for inhibiting phase separation of a wide bandgap mixed halide perovskite solar cell, wherein a certain amount of polymer solution is fully mixed with a perovskite solution before spin coating a perovskite layer in the process of preparing the solar cell; and the mixed solution is spin coated and then annealed to prepare the perovskite layer; The polymer not only needs to inhibit phase separation, but also needs to maintain a good working state of the final perovskite photovoltaic cell. Therefore, the polymer needs to have a hydrophobic group, and the polymer molecule has good light resistance and dielectric properties. The polymer is preferably PMMA (polymethyl methacrylate), PS (polystyrene), PVP (polyvinyl pyrrolidone) or SPEEK (sulfonated polyetheretherketone); The polymer concentration in the mixed solution is 0.2-1.5 mg / mL. Too small or too large a polymer additive concentration will result in poor final working condition of the perovskite photovoltaic cell.

[0006] Beneficial effects: The present invention provides a method for inhibiting phase separation of a wide-gap mixed halide perovskite solar cell, wherein the polymer additive solution and the perovskite solution are mixed in a certain proportion in the early stage, and then the mixed solution is spin-coated on a glass slide and then annealed; during the spin-coating process, the polymer additive can act on the grain boundary of the perovskite film to form an effective barrier, and the iodine and bromide ions are not easy to pass through by physical action, and the movement of bromide ions and iodine ions is limited within a single unit cell, so as to prevent the large-area aggregation of the same ions, and limit the formation and separation of iodine-rich and bromine-rich phases, thereby inhibiting phase separation; since the polymer additive can strengthen the grain boundary, it can promote the formation of a denser and smoother perovskite film during spin coating, and the high-quality perovskite film promoted by the polymer additive is conducive to the conduction of electrons and holes when the perovskite solar cell is working, and can significantly reduce the defect state density, which is conducive to the uniform stress distribution on the film surface, and greatly improves the performance of the perovskite photovoltaic device. Moreover, the method of the present invention is simple to operate and is conducive to popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of the structure of a solar cell device prepared in Example 1 of the present invention; Figure 2 The SEM images of the perovskite film surface after adding different concentrations of SPEEK in the embodiment of the present invention; Figure 3 This is a diagram showing the PL measurement results of the perovskite film surface after adding different concentrations of SPEEK in an embodiment of the present invention; Figure 4 This is a diagram showing the IV curve and efficiency measurement results of a perovskite solar cell device after adding different concentrations of SPEEK in an embodiment of the present invention. DETAILED DESCRIPTION

[0008] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments: Example

[0009] like Figure 1 As shown, the perovskite solar cell structure is ITO / NiO x / MeO-2PACz / Perovskite / C 60 / BCP / Ag, adding polymer to the perovskite precursor solution, specifically comprising the following steps: (1) The ITO glass substrate was ultrasonically treated in a mixed solution of Decon 90 detergent and deionized water (hereinafter referred to as DI water) with a volume ratio of 1:4 for 30 minutes, and the ITO glass was thoroughly cleaned with DI water and anhydrous ethanol and blown dry with nitrogen, and placed in an oven at 60°C for drying. Before preparing the device, the pre-cleaned ITO glass was treated with a plasma cleaner (PT500, LEBO Science) in an oxygen atmosphere (O2-plasma) for 2 minutes; (2) Preparation of NiO by spin coating x layer (hole transport layer), use a nozzle to remove fine dust on the ITO substrate, and drop 80 μL NiO on the ITO substrate. x The nanoparticle precursor solution (8 mg / ml dissolved in DI water) was spin-coated at a speed of 4000 rpm for 40 seconds. After the spin coating was uniform, annealing was performed at 150°C for 20 min. (3) Preparation of NiO x After the layer is formed, the sample is placed in a plasma cleaner and pure oxygen is introduced for 10 s. In a N2 atmosphere, the nozzle steps are repeated. x 80 μL of (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) (0.4 mg / ml dissolved in IPA (isopropanol)) was dropped onto the substrate, spin-coated at 4000 rpm for 30 seconds, and annealed at 100 °C for 5 minutes; (4) The perovskite absorption layer is prepared by a one-step spin coating method. The perovskite component is Cs 0.3 FA 0.7 PbI 2.7 Br 0.3; Take 101.33 mg CsI, 156.52 mg FAI, 18.07 mg PbCl2, 4.39 mg MACl, 509.41 mg PbI2, and 71.57 mg PbBr2 and dissolve them in 1 mL of DMF / DMSO (volume ratio 4:1) solvent, which is the perovskite precursor solution. Then divide the prepared solution into 200 μL portions; prepare SPEEK (sulfonated polyetheretherketone) solution (20 mg / ml dissolved in DMF), take 4 μL, 8 μL, and 12 μL of the polymer solution and add them to the previously divided perovskite precursor solutions, respectively, and mix them thoroughly to obtain three mixed solutions with final SPEEK concentrations of 0.4 mg / ml, 0.8 mg / ml, and 1.2 mg / ml; under N2 atmosphere, repeat the nozzle step, take 80 μL of the mixed solution and drop it on the previously spin-coated SAM layer, the spin coating speed is 4500 rpm, and the time is 45 s, when the spin coating countdown reaches about 20 s, 250 μL of anti-solvent CB (chlorobenzene) is dropped on the perovskite film, and finally annealed at 120 ° C for 20 min to obtain the perovskite film; (5) Finally, the sample with the spin-coated perovskite layer was placed in a vacuum evaporator and a specific mask was used to deposit the sample at 1×10 -4 Pa vacuum conditions, evaporate C 60 (Electron transport layer) 25 nm, rate 0.1 Å / s; evaporated BCP (hole blocking layer) 5nm, rate 0.1 Å / s; evaporated Ag (silver) electrode 100 nm, rate 0.5 Å / s.

[0010] Comparative Example The structure of the perovskite solar cell used is the same as that of Example 1, except that no polymer additive is added to the perovskite solution in the comparative example.

[0011] Figure 2 Figure 3 SEM images of the perovskite film surface after adding different concentrations of SPEEK. The image without SPEEK is shown in (a). There is a lot of PbI2 precipitated on the surface, and the grains are of uneven size. The stress distribution in the film is also uneven, and phase separation is prone to occur. The image when the SPEEK concentration is 0.4 mg / ml is shown in (b). Due to the low concentration of the polymer additive, some PbI2 is still precipitated on the surface. The image when the SPEEK concentration is 0.8 mg / ml is shown in (c). Due to the unsatisfactory concentration of the polymer additive, the grain size difference is more obvious than (a), and some grains with very small areas appear. The image when the SPEEK concentration is 1.2 mg / ml is shown in (d). As the concentration of the additive increases, the degree of action at the grain boundary also increases. Therefore, the grain diameter increases, the grain boundary area decreases, and the area difference between each grain is small, which reduces the probability of ion migration.

[0012] Figure 3 The PL measurement results of the perovskite film surface after adding different concentrations of SPEEK. The concentrations of (a)-(d) are 0mg / ml, 0.4mg / ml, 0.8mg / ml, and 1.2mg / ml, respectively. After 250s, the photoluminescence intensity of each sample showed a significant reduction, indicating the emergence of phase separation. After laser irradiation, the peak wavelength of (a) and (b) images shifted significantly, which may be caused by the low concentration of polymer additives. After the concentration of polymer additives increased, the peak wavelength of (c) and (d) images shifted less, and the phase separation phenomenon was suppressed.

[0013] Figure 4 The IV curves and efficiency measurement results of perovskite solar cell devices after adding different concentrations of SPEEK. The efficiency measurement results are shown in the box plot. Compared with other added concentrations, the efficiency is improved when the SPEEK concentration is 0.8 mg / ml and 1.2 mg / ml; the efficiency improvement is most significant when the SPEEK concentration is 1.2 mg / ml; It can be seen from the IV graph that the performance is optimal when the polymer concentration is 1.2 mg / ml. Example

[0014] A method for inhibiting phase separation of a wide bandgap mixed halide perovskite solar cell, in the process of preparing the solar cell, fully mixing a certain amount of PMMA (polymethyl methacrylate) solution with a perovskite solution before spin coating the perovskite layer; then spin coating the mixed solution and annealing to prepare the perovskite layer; specifically comprising the following steps: (1) The ITO glass substrate was ultrasonically treated in a mixed solution of Decon 90 detergent and deionized water (hereinafter referred to as DI water) with a volume ratio of 1:4 for 30 minutes, and the ITO glass was thoroughly cleaned with DI water and anhydrous ethanol and blown dry with nitrogen, and placed in an oven at 60°C for drying. Before preparing the device, the pre-cleaned ITO glass was treated with a plasma cleaner (PT500, LEBO Science) in an oxygen atmosphere (O2-plasma) for 2 minutes; (2) Preparation of NiO by spin coating x layer (hole transport layer), use a nozzle to remove fine dust on the ITO substrate, and drop 80 μL NiO on the ITO substrate. x The nanoparticle precursor solution (8 mg / ml dissolved in DI water) was spin-coated at a speed of 4000 rpm for 40 seconds. After the spin coating was uniform, annealing was performed at 150°C for 20 min. (3) Preparation of NiO xAfter the layer is formed, the sample is placed in a plasma cleaner and pure oxygen is introduced for 10 s. In a N2 atmosphere, the nozzle steps are repeated. x 80 μL of (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) (0.4 mg / ml dissolved in IPA (isopropanol)) was dropped onto the substrate, spin-coated at 4000 rpm for 30 seconds, and annealed at 100 °C for 5 minutes; (4) The perovskite absorption layer is prepared by a one-step spin coating method. The perovskite component is Cs 0.3 FA 0.7 PbI 2.7 Br 0.3 ; Take 101.33 mg CsI, 156.52 mg FAI, 18.07 mg PbCl2, 4.39 mg MACl, 509.41 mg PbI2, and 71.57 mg PbBr2 and dissolve them in 1 mL of DMF / DMSO (volume ratio 4:1) solvent, which is the perovskite precursor solution, and then divide the prepared solution into 200 μL portions; prepare PMMA (polymethyl methacrylate) solution (20 mg / ml dissolved in DMF), take 4 μL, 8 μL, and 12 μL of the polymer solution and add them to the previously divided portions of the perovskite precursor solution, respectively, and mix them thoroughly to obtain three mixed solutions with final PMMA concentrations of 0.4 mg / ml, 0.8 mg / ml, and 1.2 mg / ml; under N2 atmosphere, repeat the nozzle step, take 80 μL of the mixed solution and drop it on the previously spin-coated SAM layer, the spin coating speed is 4500 rpm, and the time is 45 s, when the spin coating countdown reaches about 20 s, 250 μL of anti-solvent CB (chlorobenzene) is dropped on the perovskite film, and finally annealed at 120 °C for 20 min to obtain the perovskite film; (5) Finally, the sample with the spin-coated perovskite layer was placed in a vacuum evaporator and a specific mask was used to deposit the sample at 1×10 -4 Pa vacuum conditions, evaporate C 60 (Electron transport layer) 25 nm, rate 0.1 Å / s; evaporated BCP (hole blocking layer) 5nm, rate 0.1 Å / s; evaporated Ag (silver) electrode 100 nm, rate 0.5 Å / s. Example

[0015] A method for inhibiting phase separation of a wide bandgap mixed halide perovskite solar cell, in the process of preparing the solar cell, fully mixing a certain amount of PVP (polyvinyl pyrrolidone) solution with a perovskite solution before spin coating the perovskite layer; then spin coating the mixed solution and annealing to prepare the perovskite layer; specifically comprising the following steps: (1) The ITO glass substrate was ultrasonically treated in a mixed solution of Decon 90 detergent and deionized water (hereinafter referred to as DI water) with a volume ratio of 1:4 for 30 minutes, and the ITO glass was thoroughly cleaned with DI water and anhydrous ethanol and blown dry with nitrogen, and placed in an oven at 60°C for drying. Before preparing the device, the pre-cleaned ITO glass was treated with a plasma cleaner (PT500, LEBO Science) in an oxygen atmosphere (O2-plasma) for 2 minutes; (2) Preparation of NiO by spin coating x layer (hole transport layer), use a nozzle to remove fine dust on the ITO substrate, and drop 80 μL NiO on the ITO substrate. x The nanoparticle precursor solution (8 mg / ml dissolved in DI water) was spin-coated at a speed of 4000 rpm for 40 seconds. After the spin coating was uniform, annealing was performed at 150°C for 20 min. (3) Preparation of NiO x After the layer is formed, the sample is placed in a plasma cleaner and pure oxygen is introduced for 10 s. In a N2 atmosphere, the nozzle steps are repeated. x 80 μL of (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) (0.4 mg / ml dissolved in IPA (isopropanol)) was dropped onto the substrate, spin-coated at 4000 rpm for 30 seconds, and annealed at 100 °C for 5 minutes; (4) The perovskite absorption layer is prepared by a one-step spin coating method. The perovskite component is Cs 0.3 FA 0.7 PbI 2.7 Br 0.3; Take 101.33 mg CsI, 156.52 mg FAI, 18.07 mg PbCl2, 4.39 mg MACl, 509.41 mg PbI2, and 71.57 mg PbBr2 and dissolve them in 1 mL of DMF / DMSO (volume ratio 4:1) solvent, which is the perovskite precursor solution. Then divide the prepared solution into 200 μL portions; prepare PVP (polyvinyl pyrrolidone) solution (20 mg / ml dissolved in DMF), take 4 μL, 8 μL, and 12 μL of the polymer solution and add them to the previously divided portions of the perovskite precursor solution, respectively, and mix them thoroughly to obtain three mixed solutions with final PVP concentrations of 0.4 mg / ml, 0.8 mg / ml, and 1.2 mg / ml; under N2 atmosphere, repeat the nozzle step, take 80 μL of the mixed solution and drop it on the previously spin-coated SAM layer, the spin coating speed is 4500 rpm, and the time is 45 s, when the spin coating countdown reaches about 20 s, 250 μL of anti-solvent CB (chlorobenzene) is dropped on the perovskite film, and finally annealed at 120 °C for 20 min to obtain the perovskite film; (5) Finally, the sample with the spin-coated perovskite layer was placed in a vacuum evaporator and a specific mask was used to deposit the sample at 1×10 -4 Pa vacuum conditions, evaporate C 60 (Electron transport layer) 25 nm, rate 0.1 Å / s; evaporated BCP (hole blocking layer) 5nm, rate 0.1 Å / s; evaporated Ag (silver) electrode 100 nm, rate 0.5 Å / s. Example

[0016] A method for inhibiting phase separation of a wide bandgap mixed halide perovskite solar cell, in the process of preparing the solar cell, a certain amount of PS (polystyrene) solution is fully mixed with the perovskite solution before spin coating the perovskite layer; and then the mixed solution is spin coated and annealed to prepare the perovskite layer; specifically comprising the following steps: (1) The ITO glass substrate was ultrasonically treated in a mixed solution of Decon 90 detergent and deionized water (hereinafter referred to as DI water) with a volume ratio of 1:4 for 30 minutes, and the ITO glass was thoroughly cleaned with DI water and anhydrous ethanol and blown dry with nitrogen, and placed in an oven at 60°C for drying. Before preparing the device, the pre-cleaned ITO glass was treated with a plasma cleaner (PT500, LEBO Science) in an oxygen atmosphere (O2-plasma) for 2 minutes; (2) Preparation of NiO by spin coating x layer (hole transport layer), use a nozzle to remove fine dust on the ITO substrate, and drop 80 μL NiO on the ITO substrate. xThe nanoparticle precursor solution (8 mg / ml dissolved in DI water) was spin-coated at a speed of 4000 rpm for 40 seconds. After the spin coating was uniform, annealing was performed at 150°C for 20 min. (3) Preparation of NiO x After the layer is formed, the sample is placed in a plasma cleaner and pure oxygen is introduced for 10 s. In a N2 atmosphere, the nozzle steps are repeated. x 80 μL of (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) (0.4 mg / ml dissolved in IPA (isopropanol)) was dropped onto the substrate, spin-coated at 4000 rpm for 30 seconds, and annealed at 100 °C for 5 minutes; (4) The perovskite absorption layer is prepared by a one-step spin coating method. The perovskite component is Cs 0.3 FA 0.7 PbI 2.7 Br 0.3 ; Take 101.33 mg CsI, 156.52 mg FAI, 18.07 mg PbCl2, 4.39 mg MACl, 509.41 mg PbI2, and 71.57 mg PbBr2 and dissolve them in 1 mL of DMF / DMSO (volume ratio 4:1) solvent, which is the perovskite precursor solution. Then divide the prepared solution into 200 μL portions; prepare PS (polystyrene) solution (20 mg / ml dissolved in DMF), take 4 μL, 8 μL, and 12 μL of the polymer solution and add them to the previously divided perovskite precursor solutions, respectively, and mix them thoroughly to obtain three mixed solutions with final PS concentrations of 0.4 mg / ml, 0.8 mg / ml, and 1.2 mg / ml; under N2 atmosphere, repeat the nozzle step, take 80 μL of the mixed solution and drop it on the previously spin-coated SAM layer, the spin coating speed is 4500 rpm, and the time is 45 s, when the spin coating countdown reaches about 20 s, 250 μL of anti-solvent CB (chlorobenzene) is dropped on the perovskite film, and finally annealed at 120 °C for 20 min to obtain the perovskite film; (5) Finally, the sample with the spin-coated perovskite layer was placed in a vacuum evaporator and a specific mask was used to deposit the sample at 1×10 -4 Pa vacuum conditions, evaporate C 60 (Electron transport layer) 25 nm, rate 0.1 Å / s; evaporated BCP (hole blocking layer) 5nm, rate 0.1 Å / s; evaporated Ag (silver) electrode 100 nm, rate 0.5 Å / s.

[0017] The above are only preferred embodiments of the present invention, which will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements made are all protected by the present invention.

Claims

1. A method for inhibiting phase separation of wide bandgap mixed halide perovskite solar cells, characterized in that: In the process of preparing solar cells, the polymer solution and the perovskite solution are fully mixed before preparing the perovskite layer; the perovskite layer is then prepared in the form of a mixed solution; the polymer in the prepared perovskite layer forms a barrier at the grain boundary of the perovskite film.

2. The method for inhibiting phase separation of wide bandgap mixed halide perovskite solar cells according to claim 1, characterized in that: The polymer has a hydrophobic group and has light resistance and dielectric properties.

3. The method for inhibiting phase separation of wide bandgap mixed halide perovskite solar cells according to claim 2, characterized in that: The polymer is polymethyl methacrylate, polystyrene, polyvinyl pyrrolidone or sulfonated polyetheretherketone.

4. The method for suppressing phase separation of wide bandgap mixed halide perovskite solar cells according to claim 1 or 3, characterized in that: The polymer concentration in the mixed solution is 0.2-1.5 mg / mL.

5. The method for suppressing phase separation of wide bandgap mixed halide perovskite solar cells according to claim 1, characterized in that: The preparation of the perovskite solar cell comprises the following steps: After the ITO glass substrate is cleaned and oven dried, it is treated by an O2 plasma cleaner; Spin coating of NiO x After layer annealing, repeat O2 plasma cleaning machine treatment; Continue to spin-coat SAM and then anneal; One-step spin coating to prepare the perovskite layer after adding polymer; Then evaporate C 60 , BCP and Ag to obtain the perovskite solar cell.

6. The method for suppressing phase separation of wide bandgap mixed halide perovskite solar cells according to claim 5, characterized in that: Preparation of NiO x The spin coating speed of the layer was 4000 rpm for 40 s; the annealing temperature was 150 °C for 20 min.

7. The method for suppressing phase separation of wide bandgap mixed halide perovskite solar cells according to claim 5, characterized in that: The spin coating speed for preparing the SAM layer was 4000 rpm for 30 seconds, and the annealing temperature was 100° C. for 5 minutes.

8. The method for suppressing phase separation of wide bandgap mixed halide perovskite solar cells according to claim 5, characterized in that: The spin coating conditions for preparing the perovskite layer are as follows: the spin coating speed is 4500 rpm, the time is 45 s, when the spin coating countdown reaches about 20 s, 250 μL of anti-solvent chlorobenzene is added dropwise on the perovskite film, and finally annealed at 120°C for 20 min.

9. The method for suppressing phase separation of wide bandgap mixed halide perovskite solar cells according to claim 5, characterized in that: Preparation of C by vacuum evaporation coating 60 , BCP and Ag, at 1×10 -4 Pa vacuum conditions, evaporate C 60 25nm, rate 0.1 Å / s; evaporated BCP 5 nm, rate 0.1 Å / s; evaporated silver electrode 100 nm, rate 0.5 Å / s.

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